NEVADA COUNTY, CALIFORNIA INITIAL STUDY

To: Building Department* Nevada County Public Works Dept* Nevada Co Environmental Health Dept* City of Grass Valley* Nevada County Consolidated Fire District* Nevada Irrigation District* Northern Sierra Air Quality Mmgt District* PG&E* Dan Miller, District III Supervisor* Tyler Barrington, Principal Planner* Allison Ranch Property Owners Assn* County Counsel All individuals/organizations who have requested Notice of Availability of Initial Study* All agencies notified through the State Clearinghouse as listed on the Notice of Completion * Note: NOA only Date: July 9, 2015 Prepared by: Jessica Hankins, Project Planner Nevada County Planning Department 950 Maidu Avenue, Suite 170 Nevada City, CA 95959 (530) 265-1254 Email: [email protected] File Number(s): U14-009, MGT14-015, EIS14-012 Assessor’s Parcel Numbers: 22-120-28, -35; 22-160-27; 29-290-26; 29-350-03, -04, -16 Applicant: Newmont Mining Corp. 5326 Uranium City Road Ford, WA 99013 Telephone: (509) 258-4511 Owner: New Verde Mines LLC 5326 Uranium City Road Ford, WA 99013 Telephone: (509) 258-4511 Zoning Districts: Nevada County – IDR, RA-1.5 City of Grass Valley – P General Plan Designations: Nevada County – SDA, RES City of Grass Valley – P Project Location: 12509 Allison Ranch Road, Grass Valley 95949 Application Description: A Use Permit for the construction and operation of a groundwater collection conveyance and treatment system to manage water quality of historical mine drainage; and a Management Plan to address potential impacts on riparian habitat and wetland habitat near the conveyance and treatment system. Other Permits Which May Be Necessary: Based on initial comments received, the following permits may be required from the designated agencies: 1. Grading and building permits – Nevada County Building Dept. 2. County road encroachment permit and Traffic Control Plan – Nevada County Public Works Dept. 3. Waste Discharge Requirements Order, NPDES Permit, Storm Water Pollution Prevention Plan – Central Valley Regional Water Quality Control Board 4. Dust control permit - Northern Sierra Air Quality Management District North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 2 of 113 July 9, 2015

Table of Contents

NORTH STAR WATER TREATMENT PROJECT DESCRIPTION ...... 4 Project Location and Surrounding Land Uses ...... 4 Historical Background of the Project Area ...... 5 Project Background ...... 5 Project Description...... 6 Alternatives ...... 13 Relationship to Other Projects ...... 13 SUMMARY OF IMPACTS AND PROPOSED MITIGATION MEASURES ...... 15 INITIAL STUDY AND CHECKLIST ...... 29 Introduction ...... 29 1. Aesthetics ...... 29 2. Agricultural/Forestry Resources ...... 33 3. Air Quality ...... 35 4. Biological Resources ...... 41 5. Cultural Resources ...... 54 6. Geology / Soils ...... 57 7. Greenhouse Gas Emissions ...... 65 8. Hazards / Hazardous Materials ...... 67 9. Hydrology / Water Quality ...... 73 10. Land Use / Planning ...... 76 11. Mineral Resources ...... 79 12. Noise ...... 80 13. Population / Housing ...... 83 14. Public Services ...... 84 15. Recreation ...... 85 16. Transportation / Circulation ...... 86 17. Utilities / Service Systems ...... 89 18. Mandatory Findings of Significant Environmental Effect ...... 91 RECOMMENDATION OF THE PROJECT PLANNER ...... 96 REFERENCES ...... 97 FIGURES ...... 99 1 – Project Location Map 2 – Site Plan 3 – Northern Project Area 4 – Southern Project Area 5 – Drew Tunnel Pump Station 6 – North Star Pump Station North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 3 of 113 July 9, 2015

7 – Pipe Trench and Road Details 8 – Biological Inventory Habitat Map 9 – Geologic Features 10 – Geologic Hazards Overview Map 11 – Northernmost Geologic Hazards 12 – North Central Geologic Hazards 13 – Central Geologic Hazards 14 – South Central Geologic Hazards 15 – Southernmost Geologic Hazards

TABLES 1 – Disturbance Areas ...... 7 2 – Distances from Project Features to Visually Sensitive Receptors ...... 31 3 – Project Construction Air Quality Impacts ...... 37 4 – Project Operation Air Quality Impacts ...... 38 5 – Land Use Incompatibilities and Mitigation Measures ...... 78

Acronyms and Abbreviations Used Frequently in this Initial Study

APN Assessor’s Parcel Number BYLT Bear Yuba Land Trust CEQA California Environmental Quality Act cfs cubic feet per second ESA Environmental Site Assessment gpm gallons per minute HDPE High-density polyethylene IDR Interim Development Reserve zoning district lf linear feet MCL Maximum Contaminant Level NID Nevada Irrigation District NPDES National Pollutant Discharge Elimination System NSAQMD Northern Sierra Air Quality Management District PEA Preliminary Endangerment Assessment Project Area The 70-acre project site Proposed Project The North Star Water Treatment Project RWQCB Central Valley Regional Water Quality Control Board SDA Special Development Area general plan designation TCP Timber Conversion Permit THP Timber Harvest Plan WME Worthington Miller Environmental WWTP Wastewater Treatment Plant

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NORTH STAR WATER TREATMENT PROJECT DESCRIPTION

Under a Limited Threat NPDES permit from the Central Valley Regional Water Quality Board, the North Star Water Treatment Project (Proposed Project) would treat contaminated water draining from several historical mining features, including the Drew Tunnel within the City of Grass Valley limits, and an adit, culvert, and spring in unincorporated Nevada County just south of Grass Valley on the site of the historical North Star Mine. The Proposed Project is located adjacent to Allison Ranch Road and Wolf Creek.

Project Location and Surrounding Land Uses

Project Vicinity

The 70-acre Project Area is located adjacent to or near Allison Ranch Road approximately ½ mile south of downtown Grass Valley, spanning the City of Grass Valley limits at its northernmost point and unincorporated Nevada County for the majority of its length. Portions of Nevada County Assessor’s Parcel Numbers (APNs) 29-350-03, 29-350-16, 22-120-28, 22-160-27, 29-350-04, and 22-120- 35, owned by New Verde Mines, LLC, an entity of Newmont Mining Corporation, are included in the Project Area. Under an agreement with the City, Newmont would also purchase a sufficient area of APN 29-290- 26 from the City necessary to construct the collection and conveyance system for the water draining from the Drew Tunnel. Figure 1 illustrates the project vicinity.

Location of Project Features

The Proposed Project includes facilities to collect, convey, and treat water from three mining drainage features and a spring, as depicted in Figures 2 through 4. The collection and conveyance component of the project is linear and would span an area approximately 1.5 miles long, extending along Allison Ranch Road from the City of Grass Valley Wastewater Treatment Plant (WWTP) on APN 29-290-26, south to the proposed treatment area on Mote Lane on APN 22-160-27. Mine water would be pumped from two areas: one at the Grass Valley WWTP (Drew Tunnel Pump Station) and one on APN 29-350-16 on the North Star property (North Star Pump Station), which would intercept water from an adit, culvert, and spring. The Drew Tunnel pipeline would proceed southbound on Allison Ranch Road, continue onto Allison Ranch Road Bypass (Bypass Road), and then cross under Allison Ranch Road to the east to APN 22-120-28 and connect to the North Star drainage pipeline. At the point of nexus, the two pipelines would merge and proceed south to the treatment ponds.

Project Area Zoning and Uses

Except for the area of APN 29-290-26 that would be purchased from the City (with City of Grass Valley “Public” zoning) and the construction staging area (zoned Residential-Agricultural [RA]-1.5), most of the Project Area is located within the North Star Special Development Area (SDA) and is zoned Interim Development Reserve (IDR) by Nevada County. Other surrounding zoning includes RA-1.5 throughout the southern Project Area, and City of Grass Valley R1 and R-3/PD in the northern Project Area.

In the northern area of the project site, nearby uses consist of public facilities such as the Grass Valley WWTP and Glenn Jones Park, and commercial uses such as the Pine Creek shopping center. Most of the southern area of the site is undeveloped land within the SDA or contains rural residential uses. Single- family residential parcels of the Carriage House Subdivision are located east of Wolf Creek and to the east of the central portion of the Project Area.

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The undeveloped North Star Property adjoins the western boundary of the central portion of the Project Area. Single-family rural residential parcels are situated to the east and west of the southern portion of the Project Area. Agricultural (grazing) land on the west side of Allison Ranch Road adjoins the southwest boundary of the Project Area. The North Star Pump Station is located on Newmont property that is subject to a conservation easement managed by the Bear Yuba Land Trust.

Project Area Characterization

The Project Area was subject to mining disturbance at various times in the past but is currently undeveloped. Soils are mostly extremely rocky, and the terrain varies from level to steeply sloping. Ground cover is comprised mostly of ponderosa pine woodland with some annual grassland and disturbed areas, as well as several types of riverine and wetland habitat.

The Project Area abuts and includes part of Wolf Creek, a perennial tributary of the Bear River and the Sacramento River. Several unnamed perennial and seasonal tributaries of Wolf Creek occur within the Area. Two perennial ponds also occur within the site, along with freshwater emergent wetlands and foothill riparian habitat (Ecosynthesis Scientific & Regulatory Services 2014).

Historical Background of the Project Area

Mining and logging represent the most significant past land uses of the Project Area. Mining of the North Star property ceased in 1956 (MWH 2014). Much of the waste rock that previously existed on the surface near the mine workings is no longer present. Waste rock was salvaged and crushed and screened for use as aggregate. A few relatively small waste rock piles and areas of scattered waste rock remain within the Project Area. A relatively level area adjacent to Wolf Creek on APN 22-120-28 may have been used to process waste rock for aggregate. Portions of the Project Area also appear to have been logged in the past for fire prevention.

During his period of ownership, Sandy Sanderson of North Star/Grass Valley, LLC proposed development of the approximate 714-acre North Star Property, including portions of the Project Area. Before development could occur, however, North Star/Grass Valley, LLC filed for relief under Chapter 11 of the U.S. Bankruptcy Code in November 2008. New Verde Mines had previously owned the North Star property (prior to the North Star/Grass Valley, LLC ownership), and continued to own the underlying mineral rights. In 2011 New Verde Mines re-acquired the North Star Property for the purpose of implementing the Proposed Project.

Project Background

Following closure and dewatering of the mines in the mid-1900s, groundwater levels within the underground mine workings recovered and began to drain by gravity from the mine features. Drainage from the past mining activities now contains contaminants that require remediation.

The Proposed Project arose from two separate issues at the different mine drainage feature sites. The first was Central Valley Regional Water Quality Control Board (RWQCB) Cleanup and Abatement Order R5- 2014-0706 for the mine adit, pipe culvert, and spring, at the proposed North Star Pump Station, which addressed a water quality complaint of yellowish material leaching into Wolf Creek at the site in 2008. Discharges from the mine adit and pipe culvert contain iron and manganese at concentrations that threaten to impact beneficial uses in Wolf Creek, and periodically contain arsenic at concentrations that exceed the arsenic Primary Maximum Contaminant Level (MCL) of 10 parts per billion (mg/L).

The Proposed Project would also address ongoing issues at the Drew Tunnel mine drainage. In 2000 the portal of the Drew Tunnel was exposed on the City’s WWTP property during expansion of the WWTP. The City was required to route the water from Drew Tunnel to the WWTP for treatment. In 2009 the City North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 6 of 113 July 9, 2015 entered into a settlement agreement with Newmont Mining Corporation that required Newmont to remove the Drew Tunnel water from the City’s WWTP and treat the water at a separate facility.

In 2014 Newmont and the City entered into an Agreement Regarding Installation of Temporary and Permanent Drew Tunnel Treatment Systems and General Release (Agreement). The Agreement required that Newmont set up, permit and operate a temporary green sand/multimedia water treatment system (Green Sand System) on the City’s WWTP property to treat the Drew Tunnel water. Beginning in September 2014, water draining from the Drew Tunnel has been collected and treated by Newmont at the Green Sand System with the treated effluent conveyed to Wolf Creek, under to a Limited Threat NPDES permit issued by the Regional Board. The Green Sand System has a capacity of 1.73 million gallons of water per day to remove metals from Drew Tunnel flows at a rate of up to 600 gallons per minute (gpm). The current treatment system is an “active” treatment system which requires energy, staffing, and chemicals inputs to operate. Sand and anthracite-filled tanks filter the heavy metals out of the water, and the tanks must be periodically back-flushed remove impurities, with the back-flush water returned to the WWTP for treatment.

The Agreement also requires that Newmont construct a permanent treatment system that is not located on the City’s property for the Drew Tunnel drainage, and provides for Newmont to purchase a portion of the City’s WWTP property for the installation of a pump station and piping to collect and convey the Drew Tunnel drainage to the permanent treatment system. Newmont is in the process of purchasing a sufficient area of APN 29-290-26 from the City necessary to construct and operate the Drew Tunnel pump station and conveyance piping. Once the permanent passive treatment system is constructed and operational, the temporary Green Sand System would be dismantled and removed.

Project Description

Overview

The Central Valley RWQCB Cleanup and Abatement Orders R5-2014-0706 and R5-2010-0050 require the project applicant to collect and treat contaminated water draining from three historic mine features (the Drew Tunnel, adit, culvert) and a spring in the Project Area. The Proposed Project would remove iron, arsenic, and manganese to concentrations that are below the NPDES permitted effluent limitations. Mercury is not a contaminant of concern as mercury levels within the project water features are not above the MCLs (Worthington Miller Environmental, LLC December 30, 2014).

The adit, pipe culvert, and spring are located on Newmont-owned land east of Allison Ranch Road and west of Wolf Creek, on the previous North Star Mine workings, and water from these three mine features currently drains to Wolf Creek. The third mine feature is the Drew Tunnel, which is a drainage tunnel from the Massachusetts Hill Mine. The Drew Tunnel portal is located at the City of Grass Valley WWTP, on City of Grass Valley-owned property.

The collection, conveyance, and treatment facilities would be owned and operated by Newmont, while the quality of water discharged to Wolf Creek from the treatment system would be monitored and permitted under a Limited Threat Discharge Permit from the Regional Board. Any successors in interest of the property would be responsible for maintaining the conditions of the Use Permit, Management Plan, and Limited Threat Discharge Permit.

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Disturbance Area and Construction Staging

The total disturbed area is estimated at 8.31 acres, with a breakdown shown in Table 1.

Table 1. Disturbance Areas Area of Disturbance Square feet Acres Pipeline installation (Allison Ranch Road, Bypass Road, 58,370 1.34 and other existing non-paved roads) Drew Tunnel Pump Station 3,400 0.08 North Star Pump Station 900 0.02 Sedimentation Pond 100,925 2.32 Wetland Pond and Limestone Beds 161,080 3.70 Construction Staging Area 36,964 0.85 Total 361,639 8.31

Estimated disturbed areas associated with the conveyance pipeline are comprised of the following segments:

1) Drew Tunnel pipeline from the pump station along the paved Allison Ranch Road, unpaved Bypass Road, and existing North Star Access Road The pipeline length from the Drew Tunnel pump station is approximately 3,070 lineal feet (lf) along Allison Ranch Road, 1,855 lf along the Bypass Road, and 772 lf along the partially paved North Star access road to the intersection with the North Star pipeline. These road segments are presently disturbed. The area of project disturbance would be limited to the trench width of approximately 36 inches necessary for pipe installation and is estimated to be 17,091 sf (0.39 acres). Pipeline width is

2) North Star pipeline to intersection with Drew Tunnel pipeline Approximately 1,270 lf of pipeline would extend along the old road alignment from the North Star pump station to the intersection with the Drew Tunnel pipeline. Excavating equipment to install the pipeline is estimated to result in a disturbed width of 12 feet. The disturbed area is estimated to be 15,240 sf (0.35 acres).

3) Conveyance pipeline to passive treatment system Approximately 1,377 lf of pipeline would extend to the passive treatment system along the existing old road alignment adjacent to the PG&E powerline easement, with an additional 400 lf of pipeline adjacent to the western side of the sedimentation pond. Excavating equipment to install the pipeline is estimated to result in a disturbed width of 12 feet to the sedimentation pond and 10 feet along the western side of the sedimentation basin. The disturbed area is estimated to be 20,524 sf (0.47 acres).

4) Pipeline from sedimentation pond to wetland pond Approximately 452 lf of pipeline would extend from the sedimentation pond to the wetland pond. Excavating equipment to install the pipeline is estimated to result in a disturbed width of 12 feet. The disturbed area is estimated to be 5,424 sf (0.13 acres).

The pipelines from both the Drew Tunnel pump station and the North Star pump stations to where the pipelines join would be 12-inch diameter HDPE pipe. From the intersection of the pipelines to the treatment facility would be 14-inch diameter HDPE pipe. The construction staging area would be revegetated according to the landscape plan (Mitigation Measure 1A), and the remaining disturbed areas would be reseeded per the Habitat Management Plan and erosion control measures (Mitigation Measure 4I and 6G). North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 8 of 113 July 9, 2015

Construction Schedule

The construction schedule would occur over a four to six-month period depending on weather conditions and materials availability. The scheduling of various project components would be dictated by such items as the contractor, the number of contractor crews proposed to work, and the time of the construction season. Two crews may be working simultaneously, one on pond construction and the other on the pipeline/well-vault installation.

Water Collection (Pumps and Pipelines)

Contaminated water from the drainage features would be collected and conveyed to the Proposed Project’s treatment facility. A pump station with turbine pumps would be constructed adjacent to the Drew Tunnel near the City’s WWTP to collect the water (see Figure 5), with the total pad area approximately 1,500 square feet in size. This pump station would be enclosed in a pump house structure. For the drainage features on the North Star Property (see Figure 6), a pumping well with a submersible pump would be constructed, with a total pad area of approximately 900 square feet. The purpose of the pumping well is to hydraulically collect and remove the water flowing from the North Star drainage features.

Groundwater collected from these pump systems would be conveyed by 12- and 14-inch piping to the passive water treatment facility at the southern end of the project site. The pipeline would extend from the Drew Tunnel collection system to the south along the west side of Allison Ranch Road, continue on the Allison Ranch Road bypass segment south, and then cross Allison Ranch Road in an easterly direction to an existing access road on North Star Property. The pipeline would merge with the pipeline conveying water from the North Star pumping system and continue to the proposed treatment facility area. Figure 7 illustrates the pipe trenching specifications. Each trench would be at least 2 feet wide, and pipe would be buried at least 30 inches underground along existing County roadways. The pipe would be buried at least 12 inches underground on the remainder of the North Star Property outside of existing county roadways.

Based on monitoring conducted to date, the average combined flow of all the drainage features is approximately 720 gallons per minute (gpm), and the maximum combined flow is approximately 1,970 gpm.

Treatment Facility

The proposed location of the treatment facility is on Newmont-owned property on APN 22-160-27, off Mote Lane. The treatment technology proposed is a passive treatment system with three components: a sedimentation pond(s), treatment wetland pond, and oxic limestone beds. The sedimentation pond would remove the majority of the iron through an oxidation and precipitation process. Arsenic would also precipitate in the sedimentation pond. The remaining iron would be removed in the wetlands, along with about half of the manganese. The remaining manganese would be removed in the limestone beds. Unlike active treatment systems, passive water treatment systems do not require power or hazardous chemicals such as caustic soda, sodium hypochlorite, and sodium thiosultate. They also require less maintenance than active treatment systems (Bureau of Land Management 2003). The passive treatment system components would be constructed to create a gravity flow system from the conveyance piping to the discharge point of the treatment facility. The system is sized to treat the combined flow of the drainages.

Sedimentation Ponds

Water would be released from the conveyance piping to the 2.3-acre sedimentation pond which would be approximately 47 feet east of Allison Ranch Road at its closest point. The pond would be designed to provide for a 24-hour hydraulic retention time to allow the inert suspended solids and iron oxide to settle North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 9 of 113 July 9, 2015 out of solution. Precipitation of solids in the sedimentation pond would prolong the life cycle of the wetland cell(s) and facilitate residual solids management. The sedimentation pond would be double-lined with a 60-mil HDPE liner, with a geo-grid leak detection system installed between the primary and secondary liners. A third layer of HDPE would be installed around the top of the sedimentation pond, from the rim to approximately 12 inches below normal water depth, as UV protection to promote the life of the primary HDPE liner. The operational life of the liner system is anticipated to be greater than 50 years.

The sedimentation pond’s inner and outer slopes would be at a 3:1 ratio. Because of topographical differences with slope rising from west to east and south to north, the sedimentation pond would be about 5 feet above existing ground surface at the northwest corner and at existing ground level at the northeast corner, and approximately 10 feet above existing ground surface level at the southwest corner and about 5 feet above existing ground surface level at the southeast corner.

Access to the sedimentation pond would be taken from the northeast corner and the ramp at the south end (the location of which was recently moved to provide a greater setback distance from Allison Ranch Road for aesthetic screening). The sedimentation pond would be screened with an 8-foot-tall chain link fence with redwood slats as described under “Screening/Revegetation, Fencing, and Setbacks” below. The path of travel to the south ramp would be from Mote Lane along the west side of the pond using the existing PG&E utility corridor. PG&E maintains a path of travel along this utility corridor. Following construction, only occasional equipment access to the sedimentation pond, particularly to the south ramp, would be necessary for maintenance activities. Inspections would primarily be accomplished by walking.

Sediment removal from the sedimentation pond would be required no more frequently than once every 10 years, with the actual frequency based upon sediment thickness. Sediment removal would begin with pumping the sediment into Geotubes® located on the sedimentation pond banks, allowing drain water back into the pond. Geotubes® are manufactured with “high-strength, permeable, specially engineered textiles” designed to contain and drain sediment and are essentially flexible, fully enclosed tubular filters (Tencate n.d.). After drying, the sediment would be characterized for hazardous qualities and then hauled to an approved facility. It is anticipated at this time that the sediment would be non- hazardous and would be disposed of at the Recology Ostrom Road landfill site in Yuba County. If the analysis were to find the sediment is hazardous, the material would be taken to an appropriate hazardous waste facility.

Wetlands Ponds

Water would be routed from the sedimentation pond to a 3.3-acre wetland (outside dimension; the actual water surface would be 2.5 acres) located approximately 90 feet east of Allison Ranch Road.

Aerobic wetlands treatment is a proven technology for the treatment of net-alkaline, iron-rich waters. Four processes function to remove iron and other metals in surface wetlands, as follows:

. Settlement of precipitated solids from aqueous solution . Physical filtration of colloidal precipitates by plant stalks etc. . Formation of hydroxide/oxide plaques on plant roots and rhizomes . Sorption and in-situ oxidation

The wetland pond and oxic limestone beds are designed with a single 60-mil HDPE liner that would be covered with soil and vegetation in the wetland pond and limestone in the oxic limestone beds. The wetland pond would have approximately 24 inches of growing material (soil) to support vegetation and would be planted with common rush, irisleaf rush, and small fruited bulrush (Juncus effuses, Juncus xiphioides, Scirpus microcarpus) or similar wetland species. Aerobic wetlands are shallow ponds that facilitate natural oxidation of the metals and precipitate iron, manganese, and other metals. The pond North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 10 of 113 July 9, 2015 would maintain approximately 3 to 8 inches of water above the substrate surface. The wetland pond would not be fenced.

Limestone Beds

From the wetland, water would flow to an oxic limestone bed approximately 0.36 acre in size, constructed to maximize water aeration via channel cascades and pH adjustment provided by the limestone to facilitate removal of residual manganese. Limestone treatment systems also oxidize and precipitate metals. The limestone beds would not be fenced.

Permitting and Monitoring

Permitting

The water collection, conveyance, and treatment facilities would be subject to permits issued by the Regional Board, Nevada County, City of Grass Valley, and potentially other state agencies. An agreement with the Bear Yuba Land Trust would be necessary to construct improvements for the collection and conveyance of waters from the North Star pump station on the conservation easement within APN 29- 350-16. The applicant must also purchase a portion of APN 29-290-26 at the City’s WWTP to collect and convey the Drew Tunnel water for treatment at the Proposed Project. The treated water would be released to Wolf Creek under a Limited Threat NPDES permit issued by the Regional Board.

A Timber Harvest Plan (THP) and Timberland Conversion Permit (TCP) have been submitted to CAL FIRE for the Proposed Project, to convert forested land within a 29-acre area in order to implement the project. It should be noted that the THP encompasses any potential timber harvest, and does not simply include the actual construction area. Thus, the THP necessarily includes a much larger area of tree removal where there may be a potential to remove a tree, in order to be conservative. The intent is not to remove trees or cause disturbance in the entire 29-acre area, but to have a TCP in place that would be flexible should the final County permit conditions or PG&E easement requirements cause any changes that would require any tree removal in a different location than originally planned. Actual disturbance is anticipated at 8.31 acres. CAL FIRE is the lead agency for approval of timber harvest plans and conversion permits. These permits are necessary prior to any tree removal required for project construction. The Timberland Conversion Permit is contingent on Nevada County approval of the Proposed Project. Timber harvest would not be conducted until after Nevada County project approval and until start of project construction. Timber harvest activities are evaluated and mitigated within this Initial Study and within the THP.

Leak Detection and Monitoring

As described above, the sedimentation pond would be double-lined with 60-mil high density polyethylene (HDPE) liner, with an intervening leak detection system and sump for leak extraction if it should occur. The leak detection system would consist of a geo-grid material installed between the primary and secondary liners, with instrumentation in the geo-grid layer to detect any leakage from the primary liner. Any water leakage from the primary liner would be captured by the geo-grid layer and conveyed to a sump where the water would be returned to the sedimentation pond. The sedimentation pond contains two independent ponds to provide operational flexibility and allow each pond to be drained for maintenance or repair if leakage is detected from the primary liner, while still maintaining treatment in the other pond.

The wetland pond and oxic limestone reactor beds are designed with a single 60-mil HDPE liner because the sedimentation pond would remove the majority of iron. In the wetland pond, soil would be placed above the liner to support wetland vegetation. The wetland pond is designed to have a shallow water depth of 4 to 6 inches, and all the ponds are designed with additional freeboard to contain a 100-year precipitation event. North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 11 of 113 July 9, 2015

The proposed pipeline is manufactured from HDPE, similar to what is in service at the Empire Mine State Park’s passive treatment system. These pipes are generally very resilient. The applicant would use automatic flow meters and alarms to monitor the influent into the piping system and out of the treatment system. A constant water balance would be monitored.

RWQCB staff has indicated that surface water monitoring would be required, but that groundwater monitoring is not anticipated because the sedimentation pond is double-lined with a leak detection system, the treated water would be cleaner than the water otherwise being discharged, and iron and manganese are not considered very mobile given the local soil conditions. Surface water monitoring would likely occur at monthly intervals (similar to the schedule currently used at the Drew Tunnel drainage), and monitoring locations would be depend on the flow and location of the ultimate discharge point (see Biological Resources section and Mitigation Measures 4C and 4G). If the final discharge point is situated in a seasonally dry tributary, monitoring would likely occur at the discharge point and in Wolf Creek; if the final discharge point is located within a tributary that carries sufficient flows, monitoring would occur at the discharge point and just upstream of the discharge point for comparison’s sake.

Noise-Generating Project Features

After construction is completed, little to no noise is expected from the treatment facilities, as they are designed to operate by gravity flow, with flowing water being the only moving component. Periodic inspections would be necessary and would involve one or two personnel walking the site, inspecting the facilities and collecting water samples during normal business hours. Standby electrical generators would be located at both pump stations for emergency backup electrical power, and would be periodically exercised for a minimum operating period as recommended by the generator manufacturer. Exercising periods would be for minimum time periods (minutes to hours) during daylight periods to lubricate and test mechanical and electrical components.

Screening/Revegetation, Fencing, and Setbacks

Three areas would be fenced for security and public safety: the Drew Tunnel pump station, North Star pump station, and sedimentation pond. The fencing would consist of 8-foot high galvanized chain link fencing. The fenced perimeter of the Drew Tunnel pump station would be approximately 240 lf, and approximately 70 lf of the boundary is currently fenced adjacent to the City of Grass Valley WWTP. A portion of the existing fencing would be removed to allow construction and then replaced, and approximately 170 lf of additional fencing would be installed to enclose the pump station. The perimeter fencing to enclose the North Star pump station would be approximately 30 feet by 30 feet.

As depicted on the site plan, the approximate 1,300 lf perimeter of the sedimentation pond would be enclosed by fencing. Cedar “privacy slats” would be installed in the perimeter fencing around the sedimentation pond as additional screening for aesthetic purposes.

A preliminary landscape plan has been prepared by a California-licensed landscape architect in coordination with the project biologist to minimize visual impacts and enhance natural screening of the passive treatment ponds, while providing low-maintenance and microhabitat-appropriate plant species. The landscape plan shows the retention of existing pine, cedar, and oak trees on the western perimeter of the sedimentation pond and construction staging area to provide natural screening of project features from Allison Ranch Road. The landscape plan also provides for a minimum 30-foot buffer of existing cedar trees to remain on much of the eastern boundary of the sedimentation pond. The northern boundary, northernmost part of the eastern boundary, and part of the western boundary of the sedimentation pond would also be revegetated with incense cedars, California bay tree, and coffeeberry. The construction staging area would be seeded with native plant species determined by the project biologist. The seeding would also be supplemented with at least 20 individually planted site-collected black oak acorns and North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 12 of 113 July 9, 2015 distribution of mature cones or fresh seeds of ponderosa pine. The new plantings are anticipated to require three seasons of summer irrigation, with the first season requiring more water and then decreasing as the plants become established. After three years, it is anticipated that the plantings would not require additional supplemental irrigation, though the process would be monitored for climatic conditions such as drought. Irrigation water would be provided from a temporary polythene tank located at the sedimentation pond. Above-ground irrigation tubing would be temporarily installed to supply irrigation water from the tank to the new container plants. No trenching is proposed for the irrigation lines.

The applicant proposes privacy screening within the fence fabric for the sedimentation pond. The design also provides a 30-foot setback between the fence around the sedimentation pond and the eastern property boundary to maintain the existing cedars and vegetation as a natural screen from the adjacent rural residential neighborhood. The north fence enclosing the sedimentation pond would be about 10 feet from the south edge of pavement. The western fence line of the sedimentation pond would be along the PG&E power line easement, which is set back from Allison Ranch Road, and existing trees and other vegetation would provide viewshed screening of the sedimentation pond from Allison Ranch Road in addition to privacy slats within the fence fabric.

Required setbacks for all project features in the unincorporated County area are a maximum of 30 feet from all property boundaries. The sedimentation pond would be approximately 66 feet from the Allison Ranch Road right-of-way at the western boundary at its nearest point and 30 feet from the eastern boundary of APN 22-160-27. The construction staging area is not required to meet setbacks because it does not contain any structures, but setbacks as proposed are provided here for reference. The staging area would be approximately 43 feet from the Allison Ranch Road right-of-way on the western boundary and approximately 47 feet from the eastern boundary of APN 22-160-27. The wetlands pond would be approximately 90 feet from the Allison Ranch Road right-of-way at the western boundary and 145 feet from the eastern boundary of APN 22-160-27. All other features within these areas would far exceed these setbacks. The North Star pump station would be located approximately 90 feet from the western boundary and Allison Ranch Road right-of-way, and 180 feet from the southern boundary of APN 29- 350-16. The Drew Tunnel pump station is located in the City of Grass Valley, within the Public (P) zoning district. The required setback from Allison Ranch Road for this type of use is unspecified in Grass Valley’s Zoning Code but is instead determined in the Use Permit process (Lowe 2015). The pump station would be located 20 feet from the edge of the Allison Ranch Road right-of-way.

Life-cycle Costs/Life Expectancy

Life-cycle costs would include the initial capital cost to construct the project, operation and maintenance costs, and equipment/material replacement costs. Operational costs would primarily consist of electrical costs for pumping. Additional life-cycle costs include periodic inspections, monitoring and reporting, weed and mosquito control as necessary, propane supply for backup power generators, pipeline cleaning (pigging), removal and disposal of sediment from the sedimentation pond, and other routine maintenance and equipment repair, as required. The frequency of both pipeline and sedimentation pond cleaning would need to be determined through ongoing operations, as it cannot be accurately predicted by calculation prior to commencement of operations. Life-cycle costs would also include equipment replacement depending on the projected operating life. It is estimated that pumps and controls would have a 20-year life and HDPE piping and liners would have a 50-year life span prior to replacement.

The length of treatment is indefinite as the drainages from the mine features are required to meet water quality effluent standards in perpetuity, and as long as there is groundwater (which is renewed constantly from the connected hydrology of storm water and surface water), the naturally occurring elements of iron, manganese, and arsenic would continue to leach from the mine. The life expectancy of the collection, conveyance, and treatment system is expected to be indefinite, with routine inspection, monitoring, maintenance, repair, and equipment/material replacement as needed. The system design provides for redundancy of critical elements, such as redundant pump capacity and installation of two sedimentation North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 13 of 113 July 9, 2015 pond basins within the larger sedimentation pond area. Individual pumps would be repaired or replaced when necessary. The sedimentation pond can be shifted from parallel/dual operation to single-train during average/low flow periods to provide opportunity for inspection, cleaning, maintenance, and repair when necessary. Flow can be diverted from sections of the wetland pond and oxic limestone beds during low flow periods to provide for inspection and any necessary maintenance/repair.

Alternatives

The purpose of an alternatives analysis pursuant to CEQA is to identify options that would feasibly attain the project’s objectives while reducing the significant environmental impacts resulting from the Proposed Project. CEQA does not require the inclusion of an alternatives analysis in Mitigated Negative Declaration because the Initial Study concludes that, with incorporation of mitigation measures, there would be no significant adverse impacts resulting from the Proposed Project. However, this Initial Study provides an alternatives discussion for the purposes of disclosing background information on the selection process for the location of the Proposed Project and the rejection of alternative locations and water treatment processes. The Alternatives analysis includes a discussion of the following alternatives:

. Different Location Alternative . Different Water Treatment Process Alternative . Mine Shaft Fill Alternative . No Project Alternative . Proposed Project Alternative

The Alternatives evaluation is found within Section 18 of this Initial Study.

Relationship to Other Projects

This project is not directly related to any other existing or proposed projects, nor are any projects currently anticipated for the North Star property. However, the previously proposed North Star residential project, the existing Empire Mine water treatment ponds, and planned trails in the project area are discussed below for reference purposes.

North Star Master Plan

During its period of ownership, Sandy Sanderson of North Star/Grass Valley, LLC proposed development of the approximate 714-acre North Star Property, including portions of the Project Area. The proposed development included residential, commercial, community services (e.g. community centers, fire stations), recreational, and public open space. North Star/Grass Valley, LLC also conveyed a conservation easement for APN 29-350-03 and APN 29-350-16 to the Nevada County Land Trust (presently Bear Yuba Land Trust). Before development could occur, however, North Star/Grass Valley, LLC filed for relief under Chapter 11 of the U.S. Bankruptcy Code in November 2008, with the property defaulting to Citizens Bank of Nevada County. Newmont has no ties to Sandy Sanderson or North Star/Grass Valley, LLC, and acquired the property in 2011 in order to facilitate the Proposed Project.

Empire Mine Magenta Drain

The California Department of Parks and Recreation (State Parks) is the lead agency and operator of mine water treatment ponds that are similar to those being proposed with the proposed North Star Water Treatment Facility. Newmont no longer owns the Empire Mine State Historic Park lands, but as the previous owner and operator of the Empire Mine, reached a $1.12 million Settlement Agreement and Mutual Release (Settlement Agreement) in December 2014 for the long-term operations and maintenance of the Empire Mine State Historic Park passive treatment system, as well as to reimburse State Parks for past response/clean-up costs at the Park. The cleanup costs were associated with remediating mining and North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 14 of 113 July 9, 2015 processing wastes at the Park for the protection of human health and the environment under the oversight of the Department of Toxic Substances Control (DTSC) and the RWQCB (Huggins 2015).

Although Empire Star Mines (a previous subsidiary of Newmont) previously owned and operated the Empire Mine, State Parks is the current owner and is responsible for the operation and monitoring of the Magenta Drain passive water treatment system. Newmont receives the monitoring results and other documents submitted by State Parks to the Water Board. State Parks routinely submits self-monitoring reports and recently submitted an Annual Progress Report to the Regional Board demonstrating compliance with their Time Schedule Order and final effluent limitations defined by their NPDES permit, indicating that the system is functioning for its designed purposes. Additionally, nothing in the Settlement Agreement discusses mismanagement of the passive treatment system; there have been no significant violations (the violations were considered minor reporting violations, not water quality violations) of State Park’s permit (Order R5-2012-0050) since the passive treatment system (including the ponds) began operating in December 2011 (Huggins 2015).

For comparison purposes with the Proposed Project, it should be noted that the Empire Mine sedimentation pond is approximately ¼ acre, whereas the North Star sedimentation pond would be approximately 2 acres. With a larger sedimentation pond and a larger wetland pond, more sediment is removed earlier in the treatment process, which provides an additional safeguard and requires a smaller limestone bed. Another difference between the two systems is that the Empire Mine State Historic Park uses its untreated mine water to irrigate its grounds at the rate of approximately 20 million gallons per year, so their incoming and outgoing flows are much lower than flows of the Proposed Project would be.

The vegetation mix in the wetlands pond at the Proposed Project site would be slightly different than that used at the Empire Mine wetlands pond. Alternative native wetland species were recommended for the water treatment requirements of the site, and these would be used in the Proposed Project. These species include common rush, irisleaf rush, and small fruited bulrush (Juncus effuses subsp. Pacificus, Juncus xiphioides, Scirpus microcarpus). It was also determined that additional air in the sedimentation pond and limestone beds precipitated more iron and manganese. The Proposed Project would therefore include tromps and other means to oxygenate the water (maximum 8 ppm).

Bear Yuba Land Trust Trails

There are currently no plans to install a trail along the pipeline easement. When the Proposed Project was originally conceived, one possible route was along the trail through the Bear Yuba Land Trust’s (BYLT) conservation easement on APN 29-350-03. However, that concept has since changed to place the pipeline in the roadbed/shoulder of Allison Ranch Road, and the trail is therefore no longer proposed in relation to this project. Bill Haire, the Trails Coordinator for BYLT, has also indicated that BYLT is not interested in the pipeline as a trail route in its current configuration. BYLT is in the conceptual stages of planning a new trail from Glenn Jones Park’s Northstar Mining Museum through the conservation easement, but this trail is not within or near the project alignment and is therefore not being considered with this project (Haire 2015).

North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 15 of 113 July 9, 2015

SUMMARY OF IMPACTS and PROPOSED MITIGATION MEASURES

Environmental Factors Potentially Affected: All of the following environmental factors have been considered. Those environmental factors checked below would be potentially affected by this project, involving at least one impact that is "Less Than Significant with Mitigation" as indicated by the checklist on the following pages.

2. Agriculture / Forestry 1. Aesthetics  3. Air Quality  Resources 

5. Cultural Resources  4. Biological Resources   6. Geology / Soils

7. Greenhouse Gas 8. Hazards / Hazardous 9. Hydrology / Water  Emissions  Materials  Quality

10. Land Use / Planning 11. Mineral Resources   12. Noise

13. Population / Housing 14. Public Services 15. Recreation

16. Transportation / 17. Utilities / Service 18. Mandatory Findings of  Circulation  Systems  Significance

Impacts and Recommended Mitigation Measures:

1. AESTHETICS: To offset the potential aesthetic impacts associated with the project construction and operational activities on nearby residents and passersby on Allison Ranch Road, the following mitigation measures shall be required:

Mitigation Measure 1A: Implement the landscape plan for the sedimentation pond and construction staging area. Prior to issuance of any grading or building permits, the applicant shall submit a Final Landscape Plan in substantial conformance with the Preliminary Landscape Plan and signed and stamped by a licensed landscape architect, to the Planning Department for review and approval, including the following:

a. All details depicted on the preliminary plans and any modifications included by these conditions of approval; and b. The location of all required plant materials, evenly dispersed within each required planting area; and c. A legend listing the type, number and size of plant materials, indicating both the both the required number and the provided number of each plant type. List plants for each required landscaped area. Include a listing of water usage type, or hydrozone, for each plant type. Show both common names and botanical names. Native vegetation must be included in all required plantings pursuant to subsection L-II 4.2.7.E.2.b of the Land Use and Development Code; and d. Irrigation plan per subsection L-II 4.2.7.E.3.c of the Land Use and Development Code; and e. A note that “All plantings and irrigation shall be maintained by the property owner and in any case where a required planting has not survived the property owner shall be responsible for replacement with equal or better plant materials.” North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 16 of 113 July 9, 2015

f. A note that “Fencing, including the cedar slats within the fencing, shall be maintained in perpetuity, for the life of the project. The fence and cedar slats shall be routinely checked and any slats that are broken, discolored or become degraded shall be replaced immediately.”

Prior to project operation, the landscape architect/property owner shall verify that all plant materials have been established pursuant to the approved plan. Irrigation shall be maintained for a minimum of three years for all newly seeded and planted areas.

Timing: Prior to issuance of grading and improvement plans and prior to operation Reporting: Approval of the grading and improvement plans and operational permits Responsible Agency: Nevada County Planning Department

3. AIR QUALITY: To offset the potential air quality impacts associated with the project construction activities, the following mitigation measures shall be required:

Mitigation Measure 3A: Implement dust control measures. Prior to the approval of any grading or improvement permits, to reduce impacts of short-term construction, the following standards shall be noted on all grading plans and shall be included in project bidding documents in such a way as to make them easily accessible to contractors or machinery operators working on the project, with a descriptive heading such as “Dust Control”:

a. The applicant shall implement all dust control measures in a timely manner during all phases of project development and construction. b. All material excavated, stockpiled or graded shall be sufficiently watered, treated or converted to prevent fugitive dust form leaving the property boundaries and causing a public nuisance or a violation of an ambient air standard. Watering should occur at least twice daily, with complete site coverage. c. All areas (including unpaved roads) with vehicle traffic shall be watered or have dust palliative applied as necessary for regular stabilization of dust emissions. d. All land clearing, grading, earth moving, or excavation activities on a project shall be suspended as necessary to prevent excessive windblown dust when winds are expected to exceed 20 mph. e. All on-site vehicle traffic shall be limited to a speed of 15 mph on unpaved roads. f. All inactive disturbed portions of the development site shall be covered, seeded or watered until a suitable cover is established. Alternatively, the applicant shall be responsible for applying non- toxic soil stabilizers to all inactive construction areas. g. All material transported off-site shall be either sufficiently watered or securely covered to prevent public nuisance. h. Paved streets adjacent to the project shall be swept or washed at the end of each day, or as required to remove excessive accumulation of silt and/or mud which may have resulted from activities at the project site.

Mitigation Measure 3B: Use grid power rather than diesel generators during construction where feasible. Prior to the approval of any grading or improvement permits, to reduce impacts of short-term construction, the following shall be noted on all construction/grading plans and shall be included in project bidding documents in such a way as to make them easily accessible to contractors or machinery operators working on the project, with a descriptive heading such as “Use Grid Power Where Feasible”: “Grid power shall be used (as opposed to diesel generators) for job site power needs where feasible during construction.”

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Approval of the grading permit or improvement plans Responsible Agency: Northern Sierra Air Quality Management District North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 17 of 113 July 9, 2015

Mitigation Measure 3C: Use alternatives to open burning of vegetative material. Prior to the approval of any grading or improvement permits, to reduce impacts of short-term construction, the following shall be noted on all construction/grading plans and shall be included in project bidding documents in such a way as to make them easily accessible to contractors or machinery operators working on the project, with a descriptive heading such as “Open Burning Prohibited”: “Alternatives to open burning of vegetative material on the project site shall be used by the project applicant unless deemed infeasible to the Air Pollution Control Officer (APCO). Among suitable alternatives is chipping, mulching, or conversion to biomass fuel.”

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Approval of the grading permit or improvement plans Responsible Agency: Northern Sierra Air Quality Management District

Mitigation Measure 3D: Comply with the Asbestos Airborne Toxic Control Measure (ACTM) for construction. If serpentine, ultramafic rock, or naturally occurring asbestos is discovered during construction or grading, the NSAQMD shall be notified no later than the following business day and specific requirements contained in Section 93105 of Title 17 of the California Code of Regulations shall be strictly complied with.

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Approval of the grading permit or improvement plans Responsible Agency: Northern Sierra Air Quality Management District

4. BIOLOGICAL RESOURCES: To offset the potential biological impacts associated with project construction and operation, the following mitigation measures shall be required:

Mitigation Measure 4A: Avoid and reduce impacts to nesting yellow warbler. In the event that tree removal and/or operation of mechanized equipment of any kind is proposed to be newly initiated or initiated after one weeks of non-activity within 100 feet of RW-2 or FEW-2 (specific locations identified in the Biological Inventory Report and Habitat Management Plan prepared by Ecosynthesis, dated December 19, 2014) between May 1 and July 1, surveys for nesting yellow warblers shall be conducted in any suitable nesting habitat that lies within 100 feet of all locations where equipment operation would occur. Surveys shall be conducted between 7 and 14 days prior to initiation of construction, and during morning hours only. If adult yellow warblers are detected during the survey (nest sites may not be identifiable), no equipment operation shall occur within 100 feet of the suitable nesting habitat until it is conclusively determined that no nest is present, or the nest is identified and young have fledged. This measure shall be noted on the grading and construction plans for this project.

Timing: Prior to issuance of the grading permits and improvement plans between May 1 and July 1 Reporting: Agency approval of permits and plans Responsible Agency: Planning Department

Mitigation Measure 4B: Avoid and reduce impacts to California red-legged frog (CRF). Prior to issuance of any grading or improvement permits, the project applicant shall conduct a habitat suitability assessment according to USFWS guidelines and submit this assessment for USFWS concurrence. If the assessment determines that suitable breeding habitat occurs within one or more wetlands or other waters within the site, the project applicant shall hire a qualified, County-approved biologist to conduct a full protocol survey for the species itself, according to USFWS protocol and seasonal recommendations for the Project Area. If the survey detects presence of CRF within any water bodies of the Project Area, the project shall consult with USFWS to establish protective measures that would be implemented during construction to minimize the potential for loss of individual CRF. Such measures might include, but would not be limited to, installation of barrier fences to impede CRF from moving from occupied water North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 18 of 113 July 9, 2015 bodies into areas of construction activity, minimization of the creation of temporary refuge sites in uncovered trenches or basins, and monitoring by a qualified biologist during construction activities. In the event that consultation with USFWS is not completed within a reasonable time period, such as six months, of submittal of the protocol survey results, the mitigation measure would be considered to have been satisfied if the project implements measures that have been accepted for other construction projects with similar circumstances. It is recommended but not required that the project applicant and/or the project biologist also obtain an incidental take permit if potential CRF breeding habitat in the Project Area is determined to be occupied. An incidental take permit protects the owner and contractor against penalties under the Endangered Species Act if individuals of a listed wildlife species are harmed despite the implementation of mitigation measures, and allows for capture of individuals if necessary to facilitate definitive identification.

Timing: Prior to issuance of the grading permits and improvement plans Reporting: Agency approval of permits and plans Responsible Agency: Planning Department and USFWS

Mitigation Measure 4C: Avoid and reduce impacts to foothill yellow-legged frog (FYF). If the treated water from the project treatment ponds is discharged at PT-8 (specific location identified in the Biological Inventory Report and Habitat Management Plan prepared by Ecosynthesis, dated December 19, 2014), no mitigation is required. If the treated water is discharged at ST-1 (location identified in the Biological Inventory) as currently proposed, or any other location, then the project shall survey for FYF during the appropriate season to detect breeding individuals or egg masses (likely from March through June, but may require more than one visit depending upon weather during the year when the survey occurs). If the species is not detected, no further mitigation is required. If it is present, the applicant shall reroute the treated water discharge to unnamed tributary PT-10 (location identified in the Biological Inventory).

Timing: Prior to issuance of the grading permits and improvement plans Reporting: Agency approval of permits and plans Responsible Agency: Planning Department

Mitigation Measure 4D: Avoid and reduce impacts to western pond turtle. Prior to initiation of ground-disturbing activities in the area of the pond (PP-1) (specific location identified in the Biological Inventory Report and Habitat Management Plan prepared by Ecosynthesis, dated December 19, 2014), construction supervision staff and workers shall be educated regarding the presence of western pond turtle and the measures to be taken to minimize potential impacts and on procedures in the event that an individual pond turtle or nest is discovered during construction. A biological monitor shall be present during pipeline construction within 600 feet of the pond. In addition, the pipeline trench should be covered at the end of each work day to prevent turtles from falling in and potentially becoming trapped, and it shall be inspected by the monitor each morning. If any pond turtles are discovered within the pipe trench, they shall be captured and relocated to the pond. In the event that a pond turtle nest is inadvertently disturbed during construction, any undamaged eggs shall be salvaged and transferred to a wildlife rescue facility for rearing and release into the wild.

Timing: Prior to issuance of the grading permits and improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department

Mitigation Measure 4E: Avoid and reduce impacts to pallid bat. If trees are to be removed for project construction at any time after March 30 and before September 16, acoustical surveys for the presence or absence of pallid bat shall be performed by a biologist with experience in this type of survey. If pallid bat is not detected within the project site, then no further mitigation is required. If pallid bat is detected acoustically within the site, then no trees larger than 24 inches dbh (“potential roost trees”) shall be North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 19 of 113 July 9, 2015 removed until either follow-up acoustical surveys demonstrate that pallid bats are no longer foraging within the site; or each potential roost tree that is either designated to be removed or is located within a 50 foot radius of a tree to be removed is determined definitively not to contain a hollow suitable for pallid bat roosting use; or until the period of September 16 to March 30, during which trees of any size may be removed without other mitigation for potential impacts on pallid bat.

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department

Mitigation Measure 4F: Avoid and reduce impacts to nesting raptors and migratory birds. If feasible and where possible, the applicant shall conduct tree removal and initial grading between August 15 and October 15. Alternatively, larger trees may be felled in late fall or winter and left on the ground for removal during the following construction season. If vegetation removal (tree removal or brush mastication) or ground surface disturbance (any form of grading) are to occur between May 1 and August 15, the applicant shall hire a qualified biologist to conduct nesting bird surveys, which shall occur between 7 and 14 days prior to initiation of construction, between dawn and 11 AM for small birds and avoiding mid-day for all birds. Survey work shall cover all habitat within 100 feet of vegetation removal or ground disturbance, or a greater distance in the case of raptor/owl survey: a distance of 500 feet from the limit of disturbance. In the event that nests are identified, temporary non-disturbance zones shall be the same width as the survey buffer (100-500 feet, depending on the species found to be nesting); a revisit by the biologist, with confirmed observations of fledglings in the nest vicinity, shall also be required prior to vegetation removal or soil disturbance, unless this were to be delayed past August 15.

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department

Mitigation Measure 4G: Compensate for potential wetland loss. The project shall purchase 0.048 acre of credit for perennial non-wetland surface waters and 0.025 acre of credit for seasonal wetland at an approved mitigation bank with a geographic service area including the site, or shall make a payment analogous to an in-lieu fee payment for nationwide permit impacts at an approved mitigation bank, for 0.048 acre of non-wetland waters and 0.025 acre at the rate applicable to seasonal wetland at the time that the project is initiated. In the event that the acreages of the three features in question are modified in the course of verification of the jurisdictional determination by the U.S. Army Corps of Engineers, the acreages of mitigation shall be correspondingly adjusted.

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department, US Army Corps of Engineers

Mitigation Measure 4H: Reduce potential erosion into the Seasonal Tributary ST-1. Prior to issuance of grading or improvement permits, the project shall compare the channel dimensions and gradients between ST-1 and PT-8 (the latter being known to be stable under flow regimes similar to the proposed discharge) (specific locations identified in the Biological Inventory Report and Habitat Management Plan prepared by Ecosynthesis, dated December 19, 2014) to determine whether the Seasonal Tributary segment has the capacity to conduct discharge flows year-round without resulting in significant erosion. For this purpose, hydrologic modeling of the channel watershed is not required. Comparison of channel dimensions and gradient between the seasonal and perennial segments suffices because the perennial segment provides an empirical standard of a channel in the same materials that remains stable when subjected to the same general flow regime (sustained wet-season flow from the NID canal being nearly as much as the flow of treated water). Once comparison has been, the following actions shall be taken: North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 20 of 113 July 9, 2015

a. If the Seasonal Tributary is determined to be stable under anticipated flows, no further actions are required other than the Outfall Design recommendations described below. b. If the Seasonal Tributary is not reasonably expected to remain stable, the recommended course of action would be to pipe the treated water down to a point where it can be discharged into the lower, perennial portion of the tributary immediately above or below the existing culvert. At that point, the recommendations pertaining to Outfall Design would be implemented. c. Outfall Design: In either case, the outflow structure shall be constructed as a wide rock-lined outfall without a single concentrated flow point (D50 of 4-6 inches; width: as wide as surrounding topography permits, or up to 8 feet wide at the level annual maximum flow), so as to disperse the outflows and minimize the potential for point erosion. Total width of the discharge conveyance includes “banks” outside the flow width. The outfall shall be constructed entirely outside jurisdictional limits and shall be feathered into the existing topography.

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department

Mitigation Measure 4I: Reduce construction and operational sediment conveyance to Project Area wetlands and other waters. Sediment containment (temporary BMPs) shall be installed prior to the arrival of any excavating equipment other than that used to install the BMPs. The central feature of temporary BMPs for construction of the proposed wetland pond is a silt fence installation between that project element and the wetlands and waters to the northwest. Straw rolls or wattles will not be effective and are not an acceptable BMP for sediment control in this location. Silt fencing shall be installed as follows and these criteria shall be included as a note on grading plans:

. At a minimum, the silt fencing system shall extend from the small topographic rise southeast of Perennial Pond PP-2 past the northern terminus of RW-2 (specific locations identified in the Biological Inventory Report and Habitat Management Plan prepared by Ecosynthesis, dated December 19, 2014). . To provide sufficient sediment capacity and to prevent the possibility of concentrating flows to a degree that exceeds the ability of silt fence and its supporting stakes to contain water without collapsing, the silt fence system shall be constructed in a series of short runs, each terminating in an upwardly curved downhill end forming a mini-detention area. . Silt fence shall be installed keyed into a 6-inch trench and over-backfilled. Due to the rocky nature of some of the soils present on site, a stockpile of screened material (with larger angular rocks that would damage the fabric removed) may be required for use as silt fence trench backfill. . If rocky conditions prevent satisfactory keying in of the toe of the silt fence, it may be rolled into coir netting and a seal constructed at the soil surface from suitable erosion control fibers such as a separate layer of folded coir netting. Any such deviation from the trenching specification should occur only under the Project Engineer’s authority (not by the implementing contractor alone) in consultation with a Certified Professional in Erosion and Sediment Control (CPESC) or other qualified individual with field experience monitoring BMP installations under extreme precipitation conditions. . Silt fencing shall be fabric only (no metal wire, which interferes with achieving a good join with the soil surface and, in the very constrained space that is the case for the present project, presents nearly insurmountable difficulties in removal without destabilizing the detained sediment. . Support stakes shall be at a maximum spacing of 10 feet, and less than that at the points where water is expected to be concentrated. Standard wooden stakes may not be effective in the site’s rocky soils; substitution or supplementation by metal rods may be necessary. . Additional support in the form of straw bales placed on the downhill side of the silt fencing at key locations is recommended. North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 21 of 113 July 9, 2015

. Silt fence shall be monitored, maintained, and repaired as necessary throughout construction and revegetation. It shall not be removed until the contained sediment behind it has been revegetated with a minimum absolute cover of 70 percent. . If any soil is to remain exposed during the rainy season, weather forecasts shall be monitored daily, and, whenever any amount of rainfall greater than ¼ inch is expected within the next 24 hours, any loose exposed soil shall be covered with plastic sheeting, adequately weighted over its entire surface to prevent it from blowing loose during the winds that frequently precede or accompany rainfall in the project region. Straw wattles or erosion control blankets are not recommended for use even in areas other than the one critical silt fence installation described in detail above. However, if they are used, they shall be ones fabricated entirely of biodegradable materials; no plastic. Monofilament netting entails significant risk of wildlife entrapment. If rolled products are to be used, coir netting is recommended over all other alternatives. Provisions related to equipment maintenance, storage of materials, and stabilized access points that are included in the Stormwater Pollution Prevention Plan shall be implemented and monitored as specified therein. . Additional sediment controls may also be required under the Stormwater Pollution Prevention Plan subject to approval by the Central Valley Regional Water Quality Control Board.

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department, Central Valley Regional Water Quality Control Board

Mitigation Measure 4J: Permanently revegetate disturbed area to avoid indirect impacts on nearby wetlands and other waters.

1. Soil management. The upper layer of existing soil shall be salvaged and stockpiled for use in construction of facility outslopes, on which it is important for revegetation to result in a thick stand of self-sustaining vegetation to preclude the need for costly maintenance and repair. The depth of the salvage shall be a minimum of six inches, or up to 12 inches depending on soil testing and calculation of the volume needed to construct the perimeter berms. If the soil stockpile is to be retained during the rainy season, it shall be seeded with the seed mix specified below. Vegetation resulting from seeding the stockpile will enhance the rate at which final revegetation occurs. The outer soil layer on slopes to be revegetated (such as outslopes of the proposed pond) shall not be compacted to a higher degree than 85% at optimum moisture content (OMC). If there is an engineering necessity for greater compaction of the interior, then an additional outer layer shall be installed for revegetation. Optionally, this may require creating excavator divots or subgrade benches at a one foot vertical interval to ensure that the revegetation soil layer does not slump when wet. Revegetation within the site shall not entail use of any high-nutrient amendments such as fertilizer of any nature including slow-release and biologically based fertilizers. Compost may be employed if it does not contain manure supplements and if it is tilled in when the final soil surface is established.

2. Hydroseeding and mulch. Hydraulic erosion control application shall occur as soon as possible following completion of ground disturbing activities. If hydroseeding occurs when the soil surface is dry, mulch often fails to adhere and peels off at the first rainfall. Therefore, if conditions are dry, hydraulic applications shall occur in two passes: one of water and seed, the other of hydromulch. If the surface materials are rough (which is desirable from the perspective of capturing seed and rainfall and reducing sheet flow velocities), mulch application shall be from two directions so that full coverage is achieved. Hydromulch of the outslopes of the facilities shall employ bonded fiber matrix. Hydromulch used in other areas may be of any other kind as appropriate to manufacturer’s specifications. Seed mix shall be as specified below, as based on what presently grows on site and species that are successful (not not invasive) in the area. Seed North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 22 of 113 July 9, 2015

specification is subject to revision by a qualified revegetation specialist based upon any additional soil observations or laboratory data that may be obtained:

. Vulpia (Festuca) myuros (foxtail fescue), 5 lbs PLS/acre . Festuca sp. (perennial fescue – prefer red, meadow, or hard fescue in that order), 3 lbs PLS /acre . Bromus hordeaceus (Blando brome), 7 lbs PLS /acre . Dactylis glomerata (orchard grass) and/or Festuca arundinacea (tall fescue), 1 lbs PLS /acre either . species or combined . Elymus glaucus (blue wild-rye), 3 lbs PLS /acre . Either or both of the following nitrogen-fixing species: . Lupinus nanus (sky lupine), 4 lbs PLS /acre . Trifolium hirtum (rose clover), 2 lbs PLS/acre . Ceanothus prostratus var. prostratus (squaw carpet), 20 seeds/square foot on outslopes or other slopes at 3:1 or steeper.

Lower application rates are still beneficial if insufficient seed supply is available. Seed pretreatment to enhance germination is required. If other seed sources are lacking, squaw carpet shall be the preferred backfill species.

Seed shall be delivered in separate bags, not mixed, and each bag shall be labeled with species, origin or cultivar name, germination testing information and date, and weed seed content. Seed that is unlabeled or lacks any of the labeling listed above shall be rejected. Weed seed content shall not exceed 1 percent and shall not include any species of Melilotus or any species with a Cal-IPC rating of “High” in any amount. Any seed lot not meeting these weed seed criteria shall be rejected.

3. Revegetation maintenance. Revegetated areas shall be monitored at least twice each year (May and August are suggested) for the first two years after construction is complete, and every individual of Armenian blackberry and Scotch broom that is found shall be eliminated from areas where the revegetation is critical to erosion control. Particular attention shall be paid to the berms containing the wetland pond and other facilities. Due to the close proximity of aquatic habitat, mechanical means are preferred; specifically, plants shall be uprooted rather than merely cut. Once desired revegetation species have established a dense stand of erosion-controlling vegetation, invasion by weeds may still occur, but would not be expected to jeopardize the bioengineering performance of the revegetation.

Timing: Prior to issuance of the grading permits or improvement plans and twice a year for two years Reporting: Agency approval of permits or plans Responsible Agency: Planning Department

5. CULTURAL RESOURCES: To offset potentially adverse cultural or historical resources impacts associated with the proposed activities on site, the following mitigation measure shall be required:

Mitigation Measure 5A: Halt work and contact the appropriate agencies if human remains or cultural materials are discovered during project construction. All equipment operators and employees involved in any form of ground disturbance shall be advised of the remote possibility of encountering subsurface cultural resources. If such resources are encountered or suspected, work shall be halted immediately and the Nevada County Planning Department shall be contacted. A professional archaeologist shall be retained by the developer and consulted to access any discoveries and develop appropriate management recommendations for archaeological resource treatment. If bones are encountered and appear to be human, California Law requires that the Nevada County Coroner and the North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 23 of 113 July 9, 2015

Native American Heritage Commission be contacted and, if Native American resources are involved, Native American organizations and individuals recognized by the County shall be notified and consulted about any plans for treatment. A note to this effect shall be included on the grading and construction plans for each phase of this project. Timing: Prior to issuance of the grading permits and improvement plans Reporting: Agency approval of permits and plans Responsible Agency: Planning Department

6. GEOLOGY AND SOILS: To offset the potential for adverse soils or erosion impacts to result from project grading and construction activities, the following mitigation measures shall be required:

Mitigation Measure 6A: Implement engineering controls and a maintenance program to reduce potential risks to the pipeline from unstable slopes along the Bypass Road alignment and in any area within the approximate zone of unstable slopes. Future slope movement may occur within and near the approximate zone of unstable slopes as shown on Figures 4-6 of the Geological Hazards Evaluation by MWH, especially during extremely wet conditions or during seismic events. The pipeline alignment along the Bypass Road is located upslope of an approximate zone of unstable slopes where slope movement has occurred in the past. Due to the proximity of the proposed pipeline alignment to the mapped head scarp and an approximate zone of potentially unstable slopes, the portion of the pipeline along the Bypass Road and in all other areas within the “approximate zone of unstable slopes” as shown on Figures 4-6 of the Geological Hazards Evaluation by MWH shall be designed to accommodate slope movement and/or stabilize the area to reduce the risk of pipeline deformation in the future. A monitoring and maintenance program shall be developed and implemented to regularly assess pipeline performance and verify that the system continues to perform as intended. Engineering controls and a monitoring and maintenance program shall be included in the pipeline design, based on the information provided in this report. The engineering controls and monitoring and maintenance program shall be submitted to Nevada County prior to issuance of any grading or improvement plans within the designated “approximate zone of potentially unstable slopes” in MWH’s December 2014 Geologic Hazards Evaluation.

Timing: Prior to issuance of the grading permits and improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Public Works Department and Building Department

Mitigation Measure 6B: Maintain a 50-foot buffer from areas of excessive erosion and incised drainages. In order to mitigate the potential for damage to project facilities by excessive erosion or deeply incised drainages as identified in the Geologic Hazards Evaluation by MWH dated December 2014, these areas shall be avoided by maintaining a minimum 50-foot buffer from engineered features. Additionally, in the identified “steep slope” area on Figure 3 of the Geologic Hazards Evaluation immediately northwest of TP 2, the pipeline shall be located along the west lane of Allison Ranch Road. Prior to issuance of grading permits and improvement plans, the project design shall reflect this avoidance.

Timing: Prior to issuance of the grading permits and improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Public Works Department and Building Department

Mitigation Measure 6C: Maintain a 50-foot buffer from known areas of subsidence and underground mine workings where practicable. The location of known underground mine workings shall be delineated prior to issuance of grading permits and improvement plans. Where practicable, facilities shall be constructed to avoid mapped areas of subsidence and known underground mine workings by a minimum of 50 feet offset, although those construction components that must be located within 50 feet to either collect or intercept the mine waters shall be allowed. Where these areas cannot be avoided, performance standards for engineering controls shall include the following: a) site-specific North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 24 of 113 July 9, 2015 ground control plans shall accommodate movement due to subsidence and improve the pipeline’s resistance to deformation; b) site-specific ground control plans shall avoid identified ground voids where possible; and c) site-specific ground control plans shall construct project components to ensure safe ground conditions for construction workers and the public in the near- and long-term.

Timing: Prior to issuance of the grading permits and improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Public Works Department

Mitigation Measure 6D: Implement seismic reinforcement measures to avoid potential impacts from seismic activity. In order to mitigate the potential for damage caused by ground shaking, prior to the issuance of grading permits and improvement plans, the project applicant shall incorporate the parameters included in the Geologic Hazards Evaluation by MWH dated December 2014 into the project design, which include but are not limited to factors of Peak Ground Acceleration (PGA), shear wave velocity, and earthquake event return periods to ensure that all pipelines and structures associated with the project would be structurally sound and damage-resistant during potential seismic events.

Timing: Prior to issuance of the grading permits and improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Public Works Department and Building Department

Mitigation Measure 6E: Implement the recommendations of a geotechnical evaluation for project grading and structural work. Prior to issuance of grading permits and improvement plans, a geotechnical report shall be prepared by a licensed engineer and submitted to Nevada County and recommendations therein followed for all subsequent grading and structural work. The geotechnical investigation report shall provide recommendations that ensure that fill soils are compacted to CBC standards and that any liquefiable soils, if present, are accounted for in the grading design and structural specifications for the site. Performance standards shall include the following: a) all grading and structural work shall meet the performance standards of applicable CBC regulations, b) construction methods shall be used which minimize risks to structures and do not increase the risk to the site, or to adjacent properties and their structures, from the geologic hazard; c) development shall not increase instability or create a hazard to the site or adjacent properties, or result in a significant increase in sedimentation or erosion; d) site planning shall minimize disruption of existing topography and vegetation; e) excavation and grading shall be minimized to the greatest extent practicable; f) any limitations to site disturbance, such as clearing restrictions, imposed as a condition of development approval shall be marked in the field and approved by the county prior to undertaking the project; and g) a monitoring program shall be prepared for construction activities occurring in geologic hazard areas and be marked on the face of the building permit.

Timing: Prior to issuance of the grading permits and improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department and Department of Public Works

Mitigation Measure 6F: Limit the grading season. Grading plans shall include the time of year for construction activities. No grading shall occur after October 15 or before May 1 unless the Chief Building Inspector or his/her authorized agent determines project soil conditions to be adequate to accommodate construction activities.

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department and Department of Public Works

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Mitigation Measure 6G: Prepare and implement an Erosion and Sediment Control Plan for areas outside the habitat management area. Prior to issuance of grading permits or improvement plans for all project related grading including road construction and drainage improvements, said permits or plans shall incorporate, at a minimum, the following erosion and sediment control measures:

a. During construction, Best Management Practices (BMPs) for temporary erosion control shall be implemented to control any pollutants that could potentially affect the quality of storm water discharges from the site. A Storm Water Pollution Prevention Plan (SWPPP) shall be prepared in accordance with California State Water Resources Control Board (SWRCB) requirements. This SWPPP includes the implementation of BMP's for Erosion Control, Sediment Control, Tracking Control, Wind Erosion Control, Waste Management and Materials Pollution Control. b. If applicable, topsoil shall be removed and stockpiled for later reuse prior to excavation activities. Topsoil shall be identified by the soil-revegetation specialist who will identify both extent and depth of the topsoil to be removed. c. Upon completion of grading, stockpiled topsoil shall be combined with wood chips, compost and other soil amendments for placement on all graded areas. Revegetation shall consist of native seed mixes only. The primary objectives of the soil amendments and revegetation is to create site conditions that keep sediment on site, produce a stable soil surface, resist erosion and are aesthetically similar to the surrounding native forest ecosystem. d. Geo-fabrics, jutes or other mats may be used in conjunction with revegetation and soil stabilization.

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department and Department of Public Works

7. GREENHOUSE GAS EMISSIONS: To offset potentially adverse greenhouse gas impacts associated with proposed construction activities, the following mitigation measure shall be required:

Mitigation Measure 7A: Reduce and reuse construction waste where feasible. Prior to issuance of grading and improvement permits, the applicant shall include a note on all plans to the effect that project contractors shall “Reuse and recycle construction and demolition waste (including, but not limited to, soil, vegetation, concrete, lumber, metal, and cardboard) to the greatest extent practicable.”

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department

Mitigation Measure 7B: Limit construction vehicle idling time. Prior to issuance of grading and improvement permits, the applicant shall include a note on all plans to the effect that “Construction equipment idling times shall be minimized either by shutting equipment off when not in use or reducing the maximum idling time to 5 minutes (as required by the California airborne toxics control measure Title 13, Section 2485 of California Code of Regulations [CCR]) and all construction equipment shall also be maintained and properly tuned in accordance with manufacturer’s specifications.” Clear signage shall be provided for construction workers at all access points.

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department

8. HAZARDS/HAZARDOUS MATERIALS: To offset the potential for mosquito breeding habitat in the treatment ponds, the following mitigation measure shall be required: North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 26 of 113 July 9, 2015

Mitigation Measure 8A: Routinely monitor and treat the proposed ponds for mosquito larvae. For the first two summers after construction of the treatment ponds, the applicant shall contact the Environmental Health Department’s Vector Control Division and coordinate a Vector Control inspection of the treatment ponds for mosquito larvae once a month from May through October. The Vector Control Division shall document the results of the visit. If no larvae and no potential breeding hotspots are found, no further action shall be taken beyond documentation of the visit and results. If larvae or possible breeding sites are found, Vector Control Division staff shall provide recommendations to the project applicant on engineering control methods as needed that the applicant shall implement within two weeks’ time (e.g., re-grading any shallow spots, aerating or providing movement in the water at the location of the mosquito larvae). If these methods are insufficient to prevent the breeding of mosquitoes, Vector Control shall implement alternative methods, including but not limited to installation of mosquito fish and use of Bacillus thuringiensis israelenis (BTi) or other pesticides commonly used by Vector Control. If no larvae are found after the first two summers of monitoring, no further inspections shall be required except as determined necessary by Vector Control.

Timing: Once per month for three months during the first two summers of operation and as needed thereafter Reporting: Project operation Responsible Agency: Environmental Health Department, Vector Control Division

12. NOISE: To offset the potential for noise impacts on the nearest residence, the following mitigation measures shall be required:

Mitigation Measure 12A: Limit construction work hours to 7:00 AM to 7:00 PM. During grading and construction, work hours shall be limited from 7:00 AM to 7:00 PM, Monday - Saturday. Prior to issuance of grading and building permits, improvement plans shall reflect hours of construction. Timing: Prior to issuance of grading and building permits Reporting: Agency approval of permits and plans Responsible Agency: Nevada County Planning Department

Mitigation Measure 12B: Comply with Nevada County noise standards and limit operation of generators to 8:00 AM to 5:00 PM, except as needed during an electrical power outage. For regular generator maintenance, generators shall be exercised from 8:00 AM to 5:00 PM, Monday - Friday. Additionally, IDR noise standards as shown in the table shall apply to the property line of the subject property. If the County amends the noise standards in the future, any new noise standards shall apply. Noise standards shall be enforced through a complaint-driven process via the Nevada County Code Enforcement Division.

Nevada County Exterior Noise Limits Zoning District Time Period Leq Lmax IDR 7 am – 7 pm 55 75 7 pm – 10 pm 50 65 10 pm – 7 am 40 55

Timing: During project operation Reporting: Agency approval of permits or plans Responsible Agency: Nevada County Planning Department

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16. TRANSPORTATION/CIRCULATION: To offset the potential for traffic impacts during construction, the following mitigation measures shall be required:

Mitigation Measure 16A: Implement a Traffic Control Plan during construction. Prior to the issuance of grading or improvement permits and prior to the start of construction within the Nevada County road right-of-way, the applicant shall submit to the Department of Public Works for their review and approval a complete Traffic Control Plan. The Traffic Control Plan shall include all public roadways where work is to be performed and shall indicate each stage of work, closure dates for street and section of closure (if necessary and otherwise allowed by local jurisdiction), signage, flaggers, and any other pertinent information. The Traffic Control Plan shall be reviewed and approved by the County before the contractor begins work. Specific components of the Traffic Control Plan include the following:

a. At least one lane of traffic will be kept open at all times unless prior approval is provided by the County and any affected agency. No roads will be blocked or made inaccessible, due to the contractor's work, without prior written approval of the County and affected agencies. Fire lanes will not be blocked or obstructed at any time. b. Work shall be accomplished to provide access to all side streets and properties whenever possible. If access to adjacent property cannot be provided, all property owners with restricted access shall be notified 24 hours in advance and adequate nearby parking shall be provided and maintained until direct access can be restored. The contractor shall provide for pedestrian traffic through work areas at all times. c. Traffic control, signs, and barricades shall conform to current standards. Lighted barricades shall be used when required. Special attention shall be provided to excavation and open trenching. d. Three flaggers shall be used for any one-way traffic flow situation (two working and one as standby), and shall be furnished by the contractor. The flaggers shall be properly equipped and trained. e. Where flaggers are not visible to each other, additional flaggers shall be added as required by the County, or the contractor shall use radios. f. All holes, trenches, etc., in pavement areas will be covered with 1-inch (minimum thickness) steel plates, shimmed with temporary asphalt on edges, by 5:00 p.m. or at the end of each work day. As an option to the contractor, the holes, trenches, etc., can be backfilled and all areas within pavement areas have temporary asphalt toppings. The temporary asphalt will be regularly maintained. All areas will be completely restored within 10 working days after the work has been completed at that location. g. Contractor shall display "No Parking" signs in areas of work at least 72 hours in advance. The signs shall state the day(s), date(s), and time of construction work. "No Parking" signs shall be placed in full view along the side of the road and not more than 100 feet apart. h. Contractor shall furnish, erect, maintain, and remove all necessary construction signs and barricades for the full term of the construction activities. i. Closure of streets can occur only between 8:00 a.m. and 5:00 p.m. if allowed by the County. At least 48 hours before a street closure, the contractor must receive permission from the County and provide appropriate signage that meets their specifications. Approval to close a street is valid for one day only. j. On the day the street is closed, the contractor will notify the Police/Sheriff and Fire Protection District and provide appropriate signage that meets County specifications. k. Lane closures may be made for work periods only. At the end of each work period, all components of the traffic control system shall be removed from the traveled way, shoulder, and auxiliary lanes. l. If emergency access is required during a temporary lane closure, workers will be present and available to take appropriate steps to immediately alter operations to provide access. m. Replace all striping and pavement marking disturbed by construction to preconstruction configuration. North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 28 of 113 July 9, 2015

n. Restore all existing hardscape (pavement concrete or walkways, driveways, or other surface features disturbed by the contractor's work) to the pre-construction conditions acceptable to the County. o. Prior to commencement of work, notify all affected agencies, including the appropriate Public Works Department, Police Department/Sheriff's Office, Fire Protection District, U.S. Postal Service, Disposal Services, and local ambulance/emergency response services. p. Construction activities shall be scheduled to direct traffic flow to off-peak hours as much as practicable.

Timing: Prior to issuance of grading and improvement permits for work within the County right-of-way and work that will affect traffic flow in the County right-of-way Reporting: Agency approval of permits or plans Responsible Agency: Nevada County Public Works Department

17. UTILITIES/SERVICE SYSTEMS: To offset potentially adverse impacts related to construction waste, the following mitigation measure is recommended:

Mitigation Measure 17A: Appropriately dispose of vegetative and toxic waste. Neither stumps nor industrial toxic waste (petroleum and other chemical products) are accepted at the McCourtney Road transfer station and if encountered, shall be properly disposed of in compliance with existing regulations and facilities. This mitigation measure shall be included as a note on all grading and improvement plans, which shall be reviewed and approved by the Planning Department prior to grading permit issuance. Timing: Prior to issuance of grading and improvement permits Reporting: Agency approval of permits and plans Responsible Agency: Nevada County Planning Department

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INITIAL STUDY AND CHECKLIST

Introduction

This checklist is to be completed for all projects that are not exempt from environmental review under the California Environmental Quality Act (CEQA). The information, analysis and conclusions contained in the checklist are the basis for deciding whether an Environmental Impact Report (EIR) or Negative Declaration is to be prepared. If an EIR is determined to be necessary based on the conclusions of the Initial Study, the checklist is used to focus the EIR on the effects determined to be potentially significant. This Initial Study uses the following terms to describe the level of significance of adverse impacts. These terms are defined as follows.

 No Impact: An impact that would result in no adverse changes to the environment.  Less than Significant Impact: An impact that is potentially adverse but does not exceed the thresholds of significance as identified in the impact discussions. Less than significant impacts do not require mitigation.  Less than Significant with Mitigation: An environmental effect that may cause a substantial adverse change in the environment without mitigation, but which is reduced to a level that is less than significant with mitigation identified in the Initial Study.  Potentially Significant Impact: An environmental effect that may cause a substantial adverse change in the environment; either additional information is needed regarding the extent of the impact to make the significance determination, or the impact would or could cause a substantial adverse change in the environment. A finding of a potentially significant impact would result in the determination to prepare an EIR.

1. AESTHETICS

Less Than Potentially Less Than Significant Significant Significant No Impact Would the Proposed Project: with Impact Impact Mitigation a. Result in demonstrable, negative, aesthetic effects on  scenic vistas or views open to the public? b. Substantially damage scenic resources, including but not limited to trees, rock outcroppings, and historic buildings  within a state scenic highway? c. Substantially degrade the existing visual character or  quality of the site and its surroundings? d. Create a new source of substantial light or glare, which  would adversely affect day or nighttime views in the area? e. Create a visually incompatible structure within a  designated historic district?

Existing Setting

The Project Area was subject to mining disturbance in the past but is currently undeveloped and vegetated with mostly ponderosa pine woodland, some annual grassland and disturbed areas. The Project Area abuts and includes part of Wolf Creek, a perennial tributary of Bear River and the Sacramento River. Several unnamed perennial and seasonal tributaries of Wolf Creek occur within the Project Area, which includes ponds, wetlands, and riparian habitat (Ecosynthesis Scientific & Regulatory Services, 2014). The terrain varies from level to very steeply sloping.

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The City of Grass Valley WWTP and Glenn Jones Park are located in the northern area of the project site near the Drew Tunnel Pump Station. Other northern area uses include additional public uses such as the Grass Valley Animal Shelter, and commercial uses such as the Pine Creek shopping center. The central portion of the Project Area contains single-family residential parcels of the Carriage House Subdivision east of Wolf Creek, and the undeveloped North Star Property to the west. Most of the southern area of the site, where the treatment system would be located, consists of vacant land within the SDA single-family rural residential parcels. Grazing land on the west side of Allison Ranch Road adjoins the southwest boundary of the Project Area. (Nevada County n.d.)

Impact Discussion

Impact Discussion 1a & 1c: Would the Proposed Project result in demonstrable, negative, aesthetic effects on scenic vistas or views open to the public? Would the Proposed Project substantially degrade the existing visual character or quality of the site and its surroundings?

This discussion is broken up into distinct visual resource setting at the site.

Pump Stations

The proposed Drew Tunnel pump station is not anticipated to have adverse impacts on the visual environment because it would not be visible from Allison Ranch Road but would be below the grade of the road; additionally, it would adjoin the Grass Valley WWTP, which is already a developed public, quasi-industrial use. The North Star pump station would be located approximately 100 feet from Allison Ranch Road, also not visible from the road given the steep grade of the property and vegetation that would protect the view of the pump station. These pump stations are also relatively small at only 150 square feet for the Drew Tunnel pump station, 192 square feet for the Drew Tunnel vault, and 25 square feet for the North Star pump station. Likewise, the pumps at the pipe culvert and adit, as well as the pipeline proceeding from those pumps on APN 22-120-28, would occur on land owned by New Verde Mines that is not visible from other private lands, nearby homes, or Allison Ranch Road. The Drew Tunnel pump station would be located adjacent to Allison Ranch Road, but significantly below grade.

Pipelines

Pipeline construction along the Allison Ranch Road alignment would occur within the road shoulder of the existing thoroughfare, and construction within the Allison Ranch Road Bypass would occur on private property owned by New Verde Mines that is similarly a constructed road shoulder. The pipelines would be buried and would not be visible once construction is complete.

Ponds

The proposed water treatment ponds would be located within close proximity to Mote Lane and Allison Ranch Road, as well as to residents situated on the three sides, to the east, west, and south. An 8-foot-tall galvanized chain link fence would be installed around the sedimentation pond for safety purposes, and new overhead utilities would be installed to provide power to the Drew Tunnel and North Star pump stations. Cedar “privacy slats” would be installed in the perimeter fencing around the sedimentation ponds as additional screening for aesthetic purposes.

According to the submitted site plans, the project features would be located as shown in Table 2 below. This table includes visually sensitive receptors that are within 300 feet of a project feature.

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Table 2. Distances from Project Features to Visually Sensitive Receptors Proposed Project Feature Approximate Distance to Sensitive Receptor Sensitive Receptor Sedimentation Ponds 15 feet Travelers heading east on Mote Lane 30 feet Travelers heading south on Mote Land 60 feet Travelers on Allison Ranch Road 150 feet Residence at 10675 Mote Lane 180 feet Residence at 10545 Homeward Way 276 feet Residence at 12528 Allison Ranch Road 290 feet Residence at 12396 Allison Ranch Road 475 feet Residence at 10546 King Way Residence at 480 feet 10378 King Way 633 feet Residence at 10493 King Way Wetlands Pond 90 feet Travelers on Allison Ranch Road 150 feet Travelers on Mote Lane 340 feet Residence at 12396 Allison Ranch Road Parking for Wetlands Pond 50 feet Travelers on Mote Lane 150 feet Travelers on Allison Ranch Road 300 feet Residence at 12396 Allison Ranch Road Construction Staging Area 47 feet Travelers on Allison Ranch Road 90 feet Residence at 10545 Homeward Way 190 feet Residence at 10675 Mote Lane 250 feet Residence at 12528 Allison Ranch Road 360 feet Residence at 12396 Allison Ranch Road 370 feet Residence at 12575 Allison Ranch Road 415 feet Residence at 10546 King Way 455 feet Residence at 10378 King Way 595 feet Residence at 10493 King Way 760 feet Residence at 10461 King Way

As shown in the table, the most impacted receptors are travelers on Mote Lane, who, when traveling east, would be a distance of approximately 15 feet from the edge of constructed area of the sedimentation pond. Next most impacted would be travelers on Allison Ranch Road at a distance of approximately 47 feet from the construction staging area and 60 feet from the sedimentation pond. The nearest residences, arguably the most sensitive of those impacted because of the permanence of their viewshed, would be approximately 150 feet from the sedimentation pond (10675 Mote Lane) and 90 feet from the temporary construction staging area (10545 Homeward Way).

In order to protect views from the public right-of-way on Allison Ranch Road, the applicant proposes to retain as much of the existing vegetation as possible to act as a buffer. A California-licensed landscape architect has prepared a preliminary landscape and revegetation plan in coordination with the project biologist to minimize visual impacts and enhance natural screening of the sedimentation pond, while providing low-maintenance and microhabitat-appropriate plant species, including incense cedar, coffeeberry, and California bay tree. The landscape plan shows the retention of existing pine, cedar, and oak trees on the western perimeter of the sedimentation pond and construction staging area to provide natural screening of project features from Allison Ranch Road. The landscape plan also provides for a minimum 30-foot buffer of existing cedar trees to remain along Mote Lane at its eastern extent and a single row of trees approximately 12 feet wide along Mote Lane at its northern extent. The construction staging area would also be seeded with native plant species determined by the project biologist in the Habitat Management Plan. The seeding would also be supplemented with at least 20 individually planted site-collected black oak acorns and distribution of mature cones or fresh seeds of ponderosa pine. (Worthington 2015) Irrigation and maintenance requirements for these revegetated areas are provided in the preliminary landscape plan and would be required as conditions of approval on the Proposed Project.

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A vegetative buffer of approximately 70 feet for the wetland ponds and 150 feet for the wetlands pond parking area would remain in place from Allison Ranch Road, resulting in filtered or negligible views of the wetlands ponds, parking area, and limestone beds. Because the wetlands pond would be fully vegetated, it would blend into the existing vegetated scenery and would not adversely affect a public viewshed or degrade the existing visual character of the area. The limestone beds would be located behind or north of the wetlands pond and would thus not be visible from a public viewshed.

A vegetative buffer of approximately 47 feet for the construction staging area and approximately 60 to 200 feet for the sedimentation pond from Allison Ranch Road would remain in place and provide filtered or negligible views of the redwood slat fencing. The fencing would be maintained in perpetuity for the life of the project as indicated in Mitigation Measure 1A. With implementation of the landscape plan in Mitigation Measure 1A and retention of existing vegetation for screening purposes as described above, the project would not adversely affect a public viewshed or degrade the existing visual character of the area, and adverse changes to the aesthetic environment would be less than significant with mitigation.

Impact Discussion 1b: Would the Proposed Project substantially damage scenic resources, including but not limited to trees, rock outcroppings, and historic buildings within a state scenic highway?

The Project Area is not located on a state scenic highway and does not contain scenic resources (California Department of Transportation n.d.). Therefore, there would be no impact related to damaging officially designated scenic resources on a state scenic highway.

Impact Discussion 1d: Would the Proposed Project create a new source of substantial light or glare, which would adversely affect day or nighttime views in the area?

The project does not include any new proposed exterior lighting. Therefore, there would be no impact related to light and glare on sensitive receptors from the Proposed Project.

Impact Discussion 1e: Would the Proposed Project create a visually incompatible structure within a designated historic district?

There is no special historic zoning designation in place at or near the Project Area (Nevada County n.d., City of Grass Valley 2011). The Proposed Project would result in no impact on any officially designated historic areas.

Mitigation & Residual Impact

To offset the potential aesthetic impacts associated with the project construction and operational activities on nearby residents and passersby on Allison Ranch Road, the following mitigation measures shall be required:

Mitigation Measure 1A: Implement the landscape plan for the sedimentation pond and construction staging area. Prior to issuance of any grading or building permits, the applicant shall submit a Final Landscape Plan in substantial conformance with the Preliminary Landscape Plan and signed and stamped by a licensed landscape architect, to the Planning Department for review and approval, including the following:

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a. All details depicted on the preliminary plans and any modifications included by these conditions of approval, including the retention of existing trees and vegetation to the maximum extent feasible; and b. The location of all required plant materials, evenly dispersed within each required planting area; and c. A legend listing the type, number and size of plant materials, indicating both the both the required number and the provided number of each plant type. List plants for each required landscaped area. Include a listing of water usage type, or hydrozone, for each plant type. Show both common names and botanical names. Native vegetation must be included in all required plantings pursuant to subsection L-II 4.2.7.E.2.b of the Land Use and Development Code; and d. Irrigation plan per subsection L-II 4.2.7.E.3.c of the Land Use and Development Code; and e. A note that “All plantings and irrigation shall be maintained by the property owner and in any case where a required planting has not survived the property owner shall be responsible for replacement with equal or better plant materials.” f. A note that “Fencing, including the cedar slats within the fencing, shall be maintained in perpetuity, for the life of the project. The fence and cedar slats shall be routinely checked and any slats that are broken, discolored or become degraded shall be replaced immediately.”

Prior to project operation, the landscape architect/property owner shall verify that all plant materials have been established pursuant to the approved plan. Irrigation shall be maintained for a minimum of three years for all newly seeded and planted areas.

Timing: Prior to issuance of grading and improvement plans and prior to operation Reporting: Approval of the grading and improvement plans and operational permits Responsible Agency: Nevada County Planning Department

2. AGRICULTURAL/FORESTRY RESOURCES

Less Than Potentially Less Than Significant Significant Significant No Impact Would the Proposed Project: with Impact Impact Mitigation a. Convert Prime Farmland, Unique Farmland, or Farmland of Statewide Importance (Farmland), as shown on the maps prepared pursuant to the Farmland Mapping and Monitoring  Program of the California Department of Conservation’s Division of Land Resource Protection, to non-agricultural use? b. Conflict with existing zoning for agricultural use or conflict  with a Williamson Act contract? c. Conflict with existing zoning for, or cause rezoning of, forest land (as defined in Public Resource Code section 12220(g)), timberland zoned Timberland Production Zone  (per Section L-II 2.3.C of the Nevada County Land Use and Development Code)? d. Result in the loss of forest land or conversion of forest land  to non-forest use? e. Involve other changes in the existing environment, which due to their location or nature, could result in conversion of  Farmland to non-agricultural use or conversion of forest land to non-forest use?

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Existing Setting

The Project Area is designated as “Urban” and Built-up Land” and “Other Land” according to data from the California Department of Conservation. The Project Area does not contain any Important Farmlands. An approximately 20-acre area of land west of Allison Ranch Road, across from Mote Lane, is designated as Prime Farmland and Farmland of Local Importance, and this area is used for grazing purposes. (California Department of Conservation n.d.)

Impact Discussion

Impact Discussion 2a: Would the Proposed Project convert Prime Farmland, Unique Farmland, or Farmland of Statewide Importance (Farmland), as shown on the maps prepared pursuant to the Farmland Mapping and Monitoring Program of the California Department of Conservation’s Division of Land Resource Protection, to non-agricultural use?

The majority of the area where construction would occur is Hoda sandy loam (5 to 9 percent slopes); some areas also contain Sites loam (2 to 9 percent slopes). Both Hoda sandy loam and Sites loam are listed by NRCS as soil map units that may meet the criteria for Prime Farmland as outlined in the USDA’s land inventory and monitoring program for the Nevada County area soil survey, subject to a qualification criterion related to rock content in the upper profile (less than 10 percent of the upper 6 inches consisting of rock fragments coarser than 3 inches) (USDA Soil Conservation Service 1993). However, actual designation as Prime Farmland in California requires the presence of irrigation as well as meeting the criteria. The Project Area does not contain any Important Farmlands as identified by the Farmland Mapping and Monitoring Program, and while a 20-acre area of land to the west of Allison Ranch Road from Mote Lane is designated as Prime Farmland and Farmland of Local Importance, the project would not directly or indirectly result in the conversion of these properties to non-agricultural uses (California Department of Conservation n.d.). Therefore, there would be a less than significant impact to farmlands from the Proposed Project.

Impact Discussion 2b,c: Would the Proposed Project conflict with existing zoning for agricultural use or conflict with a Williamson Act contract? Would the Proposed Project conflict with existing zoning for, or cause rezoning of, forest land (as defined in Public Resource Code section 12220(g)), timberland zoned Timberland Production Zone (per Section L-II 2.3.C of the Nevada County Land Use and Development Code)?

The Project Area is not within an area zoned for agricultural use, subject to a Williamson Act contract, or zoned for timber production (Nevada County n.d.). Therefore, the project would have no impact to farmlands and timber production lands.

Impact Discussion 2d: Would the Proposed Project result in the loss of forest land or conversion of forest land to non-forest use?

The Project Area and surrounding lands contain ponderosa pine woodland but are mostly zoned Interim Development Reserve (IDR), with only the construction staging area (zoned RA-1.5) and the Drew Tunnel Pump Station (zoned Public) designated otherwise. Once constructed, the proposed pipelines would be buried underground in the Allison Ranch Road right-of-way, which would be primarily in the road shoulder, an already disturbed area. Moreover, the areas proposed for treatment ponds are generally meadows and are not densely forested. Approximately 350 trees would be removed in the area of the sedimentation pond, wetland pond, and Drew Tunnel pump station. The majority of the trees that would North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 35 of 113 July 9, 2015 be removed are pine trees of approximately 10 to 16 inches diameter at breast height (dbh) and approximately 25 oak trees and 20 cedar trees. About 70 to 80 pine trees between 17-24 inches dbh and 30 to 40 pine trees greater than 24 inches would be removed. The Biological Inventory prepared for the project did not identify any landmark oak groves or the requirement for a County-mandated Tree Protection Plan.

Removal of these trees would occur on approximately 5.47 acres. There would be approximately 8.3 total acres of disturbance from the project, minus approximately 1.5 acres of “annual grassland/ruderal” vegetation type, which consists of previously disturbed grassy areas without a significant number of tree or shrub species in the area of the wetland pond) (Ecosynthesis Scientific & Regulatory Services 2014), minus 1.34 acres of pipeline installation within existing paved and unpaved roadbed/shoulder. This disturbance would occur over a 29-acre area and is subject to a TCP and THP from CalFire because the forest land would be converted to a different land type that would no longer support timber production. The THP is reviewed by multiple state agencies, includes CalFire, California Geological Survey (CGS), the Regional Water Board, and California Department of Fish and Wildlife. Representatives from these agencies (with the exception of the CGS) conducted a field survey of the site on June 29, 2015, and have provided revisions to the THP (Worthington 2015). The THP is a self-mitigating document that contains both the plan for timber removal and clean-up, as well as the necessary measures to reduce the impacts of converting timberland to a different use, such as safe slash disposal for hazard reduction, protection of nearby watercourses, erosion control and soil stabilization, and impacts to wildlife and plant species (CAL FIRE 2015).

Implementation of Mitigation Measure 1A would assist with the retention of the maximum number of trees feasible for project development. Impacts from conversion of this land are therefore mitigated via Mitigation Measure 1A and throughout the THP. Therefore, this project would have an impact on timber resources that is less than significant with mitigation.

Impact Discussion 2e: Would the Proposed Project involve other changes in the existing environment, which due to their location or nature, could result in conversion of Farmland to non- agricultural use or conversion of forest land to non-forest use?

Project implementation would neither directly nor indirectly result in the conversion of farmland to nonagricultural uses as noted above in Discussion 2a. There would be no impact to farmlands from this Proposed Project.

Mitigation & Residual Impacts

See Mitigation Measure 1A.

3. AIR QUALITY

Less Than Potentially Less Than Significant Significant Significant No Impact Would the Proposed Project: with Impact Impact Mitigation a. Result in substantial air pollutant emissions or  deterioration of ambient air quality? b. Violate any air quality standard or contribute to an existing  or projected air quality violation? c. Expose sensitive receptors to substantial pollutant  concentrations? North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 36 of 113 July 9, 2015

Less Than Potentially Less Than Significant Significant Significant No Impact Would the Proposed Project: with Impact Impact Mitigation d. Create objectionable smoke, ash, or odors?  e. Generate dust?  f. Exceed any potentially significant thresholds adopted in  County Plans and Goals? g. Result in a cumulatively considerable net increase of any criteria pollutant for which the project region is in non- attainment under an applicable federal or state ambient air  quality standard (including releasing emissions that exceed quantitative thresholds for ozone precursors)?

Existing Setting

Nevada County is located in the Mountain Counties Air Basin within the jurisdiction of the Northern Sierra Air Quality Management District (NSAQMD). The overall air quality in Nevada County has improved over the past decade, largely due to vehicles becoming cleaner. State and Federal air quality standards have been established for specific “criteria” air pollutants including ozone, carbon monoxide, nitrogen dioxide, sulfur dioxide, lead, and particulate matter. In addition, there are State standards for visibility reducing particles, sulfates, hydrogen sulfide, and vinyl chloride. State standards are called California Ambient Air Quality Standards (CAAQS) and federal standards are called National Ambient Air Quality Standards (NAAQS). NAAQS are composed of health-based primary standards and welfare- based secondary standards.

Western Nevada County is Marginal Nonattainment for the 1997 ozone NAAQS, with a “Finding of Attainment” based on three years of “clean” data. The area is also Marginal Nonattainment for the 2008 ozone NAAQS and is Nonattainment for the ozone CAAQS. Most of western Nevada County’s ozone is transported to the area by wind from the Sacramento area and, to a lesser extent, the San Francisco Bay Area. Ozone is created by the interaction of Nitrogen Oxides and Reactive Organic Gases (also known as Volatile Organic Compounds or VOCs) in the presence of sunlight, especially when the temperature is high. Ozone is mainly a summertime problem, with the highest concentrations generally observed in July and August, especially in the late afternoon and evening hours.

Nevada County is also Nonattainment for the PM10 CAAQS, but Unclassified for the PM10 NAAQS due to lack of available recent data. The number after “PM” refers to maximum particle size in microns. PM10 is a mixture of dust, combustion particles (smoke) and aerosols, whereas PM2.5 is mostly smoke and aerosol particles. PM2.5 sources include woodstoves and fireplaces, vehicle engines, wildfires and open burning. PM10 sources include the PM2.5 plus dust, such as from surface disturbances, road sand, vehicle tires, and leaf blowers. Some pollen and mold spores are also included in PM10, but most are larger than 10 microns. All of Nevada County is Unclassifiable/Attainment for the PM2.5 NAAQS and Unclassified for the PM2.5 CAAQS (US Environmental Protection Agency 2015).

Ultramafic rock and its altered form, serpentine rock (or serpentinite), both typically contain asbestos, a cancer-causing agent. Ultramafic rock and serpentine exist in several locations in Nevada County, mainly in the western half, but it is unlikely that these materials exist in the project area (California Department of Conservation, Division of Mines & Geology 2000).

An evaluation of project impacts related to greenhouse gas emissions is provided in Section 7 of this Initial Study.

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Impact Discussion

Impact Discussion 3a,c,e: Would the proposed project Result in substantial air pollutant emissions or deterioration of ambient air quality? Would the Proposed Project expose sensitive receptors to substantial pollutant concentrations? Would the Proposed Project generate dust?

Construction Impacts

Construction Equipment and Dust Control

Project construction activities have the potential of creating short-term air quality impacts by generating dust and impacting the local ambient air quality with grading and excavation, vegetation removal, and construction activities from site preparation and the installation of pipeline. If improperly managed or controlled, and depending upon the time of year and air conditions, the construction activities associated with this project may have the potential to produce off-site dust impacts and other construction vehicle emissions. Staff therefore conducted an analysis of project emissions using the CalEEMOD.2013.2.2 model to determine the impacts of the Proposed Project. Table 3 below illustrates the NSAQMD thresholds for various pollutants of concern compared with the project’s potential impacts shown in the CalEEMOD analysis (Northern Sierra Air Quality Management District 2009) (CalEEMod Version 2013.2.2 2015).

Table 3. Project Construction Air Quality Impacts Pollutant NSAQMD Threshold* Project Impact NOx 24-136 lbs/day 28.93 lbs/day (5.28 tons/yr) ROG 24-136 lbs/day 3.87 lbs/day (0.71 tons/yr) PM10 79-136 lbs/day 3.78 lbs/day (0.69 tons/yr) CO N/A 30.46 lbs/day (5.58 tons/yr) *These thresholds are “Level B” in NSAQMD’s Guidelines. All projects require basic mitigations under Level A, which is under 24 pounds per day of any pollutant shown above.

While total PM10 emissions would not reach the NSAQMD significance threshold, Mitigation Measure 3A nevertheless requires the use of appropriate dust control methods during construction to reduce short- term construction impacts. The CalEEMod model found that ROG impacts (both construction and operational) are far below the level of significance adopted by the NSAQMD at 3.87 pounds per day. However, the project would exceed the NSAQMD threshold of 24 ppd during construction for NOx, with 5.28 tons per year or 28.93 ppd of NOx during construction (far less during project operations). Triggering the NSAQMD threshold during construction activities requires the implementation of dust control (Mitigation Measure 3A), the use of grid power rather than diesel generators when feasible (Mitigation Measure 3B), the prohibition of open burning (Mitigation Measure 3C), and temporary traffic control and construction scheduled to direct traffic flow to off-peak hours as much as practicable (Mitigation Measure 16A). The NSAQMD does not have significant thresholds for CO levels. However, the implementation of Mitigation Measures 3B and 16A would help to reduce CO impacts from construction emissions.

Open Burning

Site preparation activities would require the conversion of approximately 8.31 acres of forested land, over a 29-acre area, to other uses. Improper disposal of this vegetation, such as through open burning, would impact the local ambient air quality. Mitigation Measure 3C prohibits the use of open burning.

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Ultramafic Rock

Although unlikely, the Project Area has the potential to contain ultramafic rock (California Department of Conservation, Division of Mines & Geology 2000). As noted above, ultramafic rock typically contains asbestos, a cancer-causing agent. Disturbance of this rock and nearby soil during project construction can result in the release of microscopic cancer-causing asbestos fibers into the air, resulting in potential health and safety hazards. Health risks related to project grading would be reduced by the incorporation of Mitigation Measure 3D, which would require compliance with the Asbestos Airborne Toxic Control Measure (ACTM) for construction.

Operational Impacts

Table 4 below illustrates the NSAQMD thresholds for various pollutants of concern compared with the project’s potential impacts shown in the CalEEMOD analysis (Northern Sierra Air Quality Management District 2009) (CalEEMod Version 2013.2.2 2015).

Table 4. Project Operation Air Quality Impacts Pollutant NSAQMD Threshold* Project Impact NOx 24-136 lbs/day 0 lbs/day (0 tons/yr) ROG 24-136 lbs/day 8.149 lbs/day 1.3497 tons/yr) PM10 79-136 lbs/day 0 lbs/day (0 tons/yr) CO N/A 12.07 lbs/day (2.00 tons/yr) *These thresholds are “Level B” in NSAQMD’s Guidelines. All projects require basic mitigations under Level A, which is under 24 pounds per day of any pollutant shown above.

As seen in Table 4, long-term development of the Project Area is not expected to create significant air quality impacts as the treatment system is passive and does not require full-time employees. Occasional inspection and adjustment by contract maintenance personnel would be needed, and some project components would need periodic replacement and service, but traffic resulting from this is expected to be infrequent and minimal.

Short-term project construction activities have the potential of generating dust, smoke, NOx, and ultramafic rock impacts on the ambient air quality within the local area. Mitigation Measures 3A, 3B, 3C, 3D, and 16A would reduce short-term construction impacts to a level that is less than significant with mitigation.

Impact Discussion 3b: Would the Proposed Project violate any air quality standard or contribute to an existing or projected air quality violation?

Nevada County has two known air quality problems: PM10 and ozone (US Environmental Protection Agency 2015). The common source for PM10 violations in the winter is from inefficient wood burning devices. During the drier months, wildfires also contribute to PM10 violations. Ground level ozone is not emitted directly into the air, but is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of sunlight. Emissions from industrial facilities and electric utilities, motor vehicle exhaust, gasoline vapors, and chemical solvents are some of the major sources of NOx and VOC. Because the project does not include proposals to construct significant structures, this impact is expected to be less than significant.

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Impact Discussion 3d: Would the Proposed Project create objectionable smoke, ash, or odors?

The proposed water treatment systems would be similar in nature to the existing passive treatment system at Empire Mine. Planning staff assessed the Empire Mine site for odors, and none were discerned (Hankins 2015). Odors likely do not occur because the water is moving and not stagnant, and does not contain biological contaminants. The mineral contaminants of manganese, iron, and arsenic and their oxidized forms do not emit an odor. Additionally, Donna Ernst, the Senior Project Environmental Scientist at Golder & Associates for the Empire Mine water treatment project, has indicated that there have not been any odor complaints on the Empire Mine treatment ponds (Ernst 2015). Therefore, this project would not generate objectionable smoke, ash, or odors, and this impact is less than significant.

Impact Discussion 3f: Would the Proposed Project exceed any potentially significant thresholds adopted in County Plans and Goals?

Nevada County’s 1995 General Plan, Chapter 14 Air Quality Element, contains several policies to protect air quality in Nevada County. With the exception of General Plan Air Quality Element Policy 14.7A, which requires compliance with NSAQMD Rule 226, Nevada County General Plan Air Quality Element policies are intended to apply to development that generates new residents or new employees (Nevada County 1995 with revisions through October 2014). Mitigation Measure 3A requires compliance with Rule 226, which is related to the control of dust emissions during construction. The proposed development of the Project Area would therefore have an impact that is less than significant with mitigation with regard to Nevada County goals and policies.

Impact Discussion 3g: Would the Proposed Project result in a cumulatively considerable net increase of any criteria pollutant for which the project region is in non-attainment under an applicable federal or state ambient air quality standard (including releasing emissions that exceed quantitative thresholds for ozone precursors)?

The Proposed Project would result in a temporary but incrementally small net increase in pollutants due to construction vehicle and equipment emissions. However, Mitigation Measure 3A, as well as compliance with the County’s grading ordinance, would reduce impacts to the extent that the project would not contribute to a cumulatively considerable net increase for ozone and PM10, for which the County is in non-attainment. Therefore, this impact is less than significant with mitigation.

Mitigation & Residual Impact

To offset the potential air quality impacts associated with the project construction activities, the following mitigation measures shall be required:

Mitigation Measure 3A: Implement dust control measures. Prior to the approval of any grading or improvement permits, to reduce impacts of short-term construction, the following standards shall be noted on all grading plans and shall be included in project bidding documents in such a way as to make them easily accessible to contractors or machinery operators working on the project, with a descriptive heading such as “Dust Control”:

a. The applicant shall implement all dust control measures in a timely manner during all phases of project development and construction. b. All material excavated, stockpiled or graded shall be sufficiently watered, treated or converted to prevent fugitive dust form leaving the property boundaries and causing a public nuisance or a North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 40 of 113 July 9, 2015

violation of an ambient air standard. Watering should occur at least twice daily, with complete site coverage. c. All areas (including unpaved roads) with vehicle traffic shall be watered or have dust palliative applied as necessary for regular stabilization of dust emissions. d. All land clearing, grading, earth moving, or excavation activities on a project shall be suspended as necessary to prevent excessive windblown dust when winds are expected to exceed 20 mph. e. All on-site vehicle traffic shall be limited to a speed of 15 mph on unpaved roads. f. All inactive disturbed portions of the development site shall be covered, seeded or watered until a suitable cover is established. Alternatively, the applicant shall be responsible for applying non- toxic soil stabilizers to all inactive construction areas. g. All material transported off-site shall be either sufficiently watered or securely covered to prevent public nuisance. h. Paved streets adjacent to the project shall be swept or washed at the end of each day, or as required to remove excessive accumulation of silt and/or mud which may have resulted from activities at the project site.

Mitigation Measure 3B: Use grid power rather than diesel generators during construction where feasible. Prior to the approval of any grading or improvement permits, to reduce impacts of short-term construction, the following shall be noted on all construction/grading plans and shall be included in project bidding documents in such a way as to make them easily accessible to contractors or machinery operators working on the project, with a descriptive heading such as “Use Grid Power Where Feasible”: “Grid power shall be used (as opposed to diesel generators) for job site power needs where feasible during construction.”

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Approval of the grading permit or improvement plans Responsible Agency: Northern Sierra Air Quality Management District

Mitigation Measure 3C: Use alternatives to open burning of vegetative material. Prior to the approval of any grading or improvement permits, to reduce impacts of short-term construction, the following shall be noted on all construction/grading plans and shall be included in project bidding documents in such a way as to make them easily accessible to contractors or machinery operators working on the project, with a descriptive heading such as “Open Burning Prohibited”: “Alternatives to open burning of vegetative material on the project site shall be used by the project applicant unless deemed infeasible to the Air Pollution Control Officer (APCO). Among suitable alternatives is chipping, mulching, or conversion to biomass fuel.”

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Approval of the grading permit or improvement plans Responsible Agency: Northern Sierra Air Quality Management District

Mitigation Measure 3D: Comply with the Asbestos Airborne Toxic Control Measure (ACTM) for construction. If serpentine, ultramafic rock, or naturally occurring asbestos is discovered during construction or grading, the NSAQMD shall be notified no later than the following business day and specific requirements contained in Section 93105 of Title 17 of the California Code of Regulations shall be strictly complied with.

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Approval of the grading permit or improvement plans Responsible Agency: Northern Sierra Air Quality Management District

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4. BIOLOGICAL RESOURCES

Less Than Potentially Less Than Significant Significant Significant No Impact Would the Proposed Project: with Impact Impact Mitigation a. Have a substantial adverse effect, either directly or through habitat modifications, on any species identified as a candidate, sensitive, or special-status species in local or regional plans,  policies, or regulations, or by the California Department of Fish and Game or U.S. Fish and Wildlife Service? b. Have a substantial adverse effect on any riparian habitat or other sensitive natural community identified in local or regional  plans, policies, regulations, or by the California Department of Fish and Game or US Fish and Wildlife Service? c. Result in a substantial reduction in the extent, diversity, or quality of native vegetation, including brush removal for fire  prevention and flood control improvements? d. Have a substantial adverse effect on federally protected wetlands as defined by Section 404 of the Clean Water Act (including, but not limited to, marsh, vernal pool, coastal, etc.)  through direct removal, filling, hydrological interruption, or other means? e. Interfere substantially with the movement of any native resident or migratory fish or wildlife species or with  established native resident or migratory wildlife corridors, or impede the use of native wildlife nursery sites? f Conflict with any local policies or ordinances protecting biological resources, such as a tree preservation policy or  ordinance? g. Introduce any factors (light, fencing, noise, human presence and/or domestic animals), which could hinder the  normal activities of wildlife?

Existing Setting

The information for this section of the Initial Study is based on the Biological Inventory Report and Habitat Management Plan prepared by Adrian Juncosa of Ecosynthesis Scientific & Regulatory Services, Inc., dated December 19, 2014 (Ecosynthesis Scientific & Regulatory Services 2014), and the addendum to the report, North Star Mine Water Treatment Project Biological Questions, dated June 18, 2015 (Ecosynthesis Scientific and Regulatory Services, Inc. 2015). Most of the Project Area lies between Allison Ranch Road and Wolf Creek, with a small conveyance portion on the Allison Ranch Road Bypass. The elevation of the site varies from approximately 2,200 to 2,400 feet, and the predominant vegetation is mixed conifer forest dominated by ponderosa pine and incense cedar. The local setting of the Project Area is mostly undeveloped, with a wastewater treatment plant on the north end of the site and occupied residential parcels adjoining the eastern and southern parts of the site. The Project Area itself has been subject to diverse mining activities since the 19th century, and some mining-related features remain, as well as a few unpaved roads, culverts, and power poles.

Soils in the Project Area are Hoda sandy loam (5 to 9 percent and 9 to 15 percent slopes), Sites loam (2 to 9 percent and 15 to 30 percent slopes), and Sites very stony loam (15 to 30 percent slopes). The majority of the area where construction would occur is Hoda sandy loam. This soil typically consists of about 12 inches of sandy loam and an additional six inches of loam overlying a relatively thick layer of clay North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 42 of 113 July 9, 2015 extending to about four feet in depth. Hoda soil in general provides highly suitable material to support plant growth.

The most extensive vegetation type by far on the site, covering 63.7 acres, is ponderosa pine woodland, which has a canopy comprised mainly of ponderosa pine with a small proportion of incense cedar and California black oak. Douglas-firs and madrones are present but relatively rare. Forest on steeper slopes, immediately above and below Allison Ranch Road, includes canyon live oak as well. In areas close to Wolf Creek, individuals of several common woody riparian species occur as a non-dominant part of the canopy: box-elder, white alder, and California walnut. Understory is highly variable throughout the forest depending on microsite. Some of the area has sufficiently dense tree canopy that there is very little by way of shrub or herbaceous layer. The predominant native understory species are whiteleaf manzanita, hoary coffeeberry, and poison oak. Non-native species are also common, including Armenian blackberry, Scotch broom, and tree-of-heaven. No areas of the ponderosa pine forest support a 30 percent canopy of oak species or a landmark oak grove. There are also no individual landmark oak trees.

Annual grassland/ruderal vegetation covers 2.7 acres and occurs in areas that appear to have been graded in the past. The largest disturbed location within the Project Area is at the location of the former aggregate processing plant where the wetlands pond is proposed. It supports scanty vegetation of mostly non-native forbs such as plantain and cat’s-ear, and some small Mediterranean grasses. Waste rock piles west of Allison Ranch Road support ripgut brome, tarweed, and foxtail fescue. The disturbed areas along the internal road that was improved to provide a bypass around the Allison Ranch Road slide are vegetated by several common erosion control species such as fescue and Lewis’s flax.

Other smaller areas of plant communities were found as follows (also see Figure 8):

Blackberry 0.24 acre Foothill riparian/bigleaf maple forest 0.12 acre Riparian wetland 0.49 acre Freshwater emergent wetlands 0.55 acre Mixed fen wetlands 0.1 acre Perennial ponds (2) 0.17 acre and 0.03 acre

The southern perennial pond of 0.03 acre and associated riparian and freshwater emergent wetlands are connected to the perennial tributary by a segment of seasonal tributary. This feature flows during the winter and spring, but not during the summer and fall. It supports practically no hydrophytic plant species. There are also two aquatic features that are the outflows from an old mine tunnel. Their vegetation cover is very low, so they are non-wetland waters, and they are both perennial and tributary to Wolf Creek.

Riverine features within the Project Area are found within 2.1 acres, mostly within Wolf Creek, which is one of the major perennial creeks in the region. It has substantial perennial flow and a gradient of 2.7 percent. Within the Project Area, Wolf Creek ends abruptly at the ordinary high water mark, with virtually no adjacent wetland floodplain. The lower part and western fork of the unnamed tributary of Wolf Creek (Perennial Tributary 8 [PT-8] and PT-9 as shown in Figure 2 of the Biological Inventory) are normally very long-seasonal or perennial, largely because any Nevada Irrigation District (NID) water that remains unused at the terminus of the Allison Ranch Canal on the west side of Allison Ranch Road then flows through a culvert and into the upper end of the west fork of the tributary.

The gradient of the main stem of the tributary (PT-10 on the map) is about 10 percent at the lower end, where it enters the perennial pond, and about 1 percent further upstream. Most of this feature is a relatively narrow channel with very stable bed and banks, but there are wider portions that appear possibly to have been scoured out during some recent high-flow event(s). The west fork, between the North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 43 of 113 July 9, 2015 culvert on site and the one under Allison Ranch Road (PT-11), has an extremely steep gradient of 12.3 percent but is also extremely erosionally stable, with no discernible evidence of lateral or vertical erosion.

Discharge of treated effluent from the Proposed Project would outfall to Seasonal Tributary 1 (ST-1), and then to unnamed tributary PT-10 into which ST-1 flows.

Impact Discussion

Impact Discussion 4a: Would the Proposed Project have a substantial adverse effect, either directly or through habitat modifications, on any species identified as a candidate, sensitive, or special- status species in local or regional plans, policies, or regulations, or by the California Department of Fish and Game or U.S. Fish and Wildlife Service?

The project biologist, Adrian Juncosa, conducted multiple field surveys in 2013 and 2014, including dates within the blooming time for the special-status plant species that have the potential to occur. A total of approximately 90 hours were spent on botanical surveys, wetland delineations, and general biological reconnaissance. Locations of specific habitat and environmental features referenced in this section are identified in Figure 8.

Special Status Plant Species

Mr. Juncosa conducted a comprehensive floristic botanical survey, including wetland areas that are not proposed to be affected, and no special-status plant species were found with the exception of the Humboldt lily (Lilium humboldtii). This plant has a California Rare Plant Rank (formerly California Native Plant Society [CNPS] List) of 4, which is described in the CDFW special plants list as a species of limited distribution for which the list states “their vulnerability or susceptibility to threat appears low at this time. While we cannot call these plants ‘rare’ from a statewide perspective, they are uncommon enough that their status should be monitored regularly.” Mr. Juncosa identified Humboldt lily on the slope above Allison Ranch Road, outside the proposed area of disturbance from pipeline construction. Therefore, the Proposed Project would thus not result in any significant impacts on this or other special- status plant species.

Special-Status Wildlife Species

The following special-status wildlife species have the potential to occur within or near areas of construction disturbance:

. Yellow warbler (State Species of Concern) . California red-legged frog (Federal Threatened and State Species of Concern) . Foothill yellow-legged frog (State Species of Concern) . Western pond turtle (State Species of Concern) . Pallid bat (State Species of Concern) . Spotted bat (State Species of Concern) . Townsend’s big-eared bat (State Species of Concern and candidate for State Threatened) . Western mastiff bat (State Species of Concern) . Western red bat (State Species of Concern)

Yellow Warbler

Yellow warbler nests in riparian and other broad-leaved woody vegetation near water. If any active nests were present at the time construction is initiated, construction that occurs near riparian wetland could North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 44 of 113 July 9, 2015 result in disturbance of one or more nesting pairs. The Project Area provides abundant nesting opportunity for the species, so if construction were already ongoing at the time that birds migrate into the area to select nest sites, they would select nest sites far enough from the disturbance that the birds in question would judge it to be tolerable. Accordingly, a potentially significant impact is identified only if construction within 100 feet of riparian wetland habitat occurs after nesting habitat is already be occupied. If daily (or at least frequent) equipment operation is initiated prior to May 1, no nest disturbance would be expected to occur. The initiation of equipment operations within 100 feet of Riparian Wetland 2 (RW-2) or Freshwater Emergent Wetland 2 (FEW-2) as shown on Figure 8 between May 1 and July 1 could result in disturbance and possible abandonment of occupied yellow warbler nests. If construction occurs during nesting season, this impact would be mitigated with Mitigation Measure 4A, which requires surveys for yellow warbler nests and cessation of construction if found.

California Red-legged Frog

California red-legged frog (CRF) breeds in long-seasonal, slow-flowing, or stagnant water, and moves into upland habitat considerable distances away from water (extending at least as far as the entire Area) to hibernate during the non-breeding season. Suitable habitat for both of these phases of the life cycle occurs within the Project Area, and habitat suitable for aestivation occurs within the footprint of proposed construction. Although no impacts on the suitable breeding habitat are proposed, grading and equipment operation could result in death of individual CRF that are moving or hibernating. Following completion of project construction, there would be no residual adverse effects on CRF, so mitigation is required only for the construction period. Mitigation Measure 4B requires an evaluation of CRF habitat for submittal to US Fish & Wildlife Service (USFWS) and a protocol-level survey for CRF if USFWS finds that suitable habitat is present. This mitigation would reduce impacts to CRF.

Foothill Yellow-legged Frog

Foothill yellow-legged frog (FYF) is highly aquatic, but requires a specific and narrow range of conditions for breeding. Specifically, it requires channels with slow to moderate flows (neither stagnant water nor high-flow creeks and rivers), or edges of large channels where these conditions occur. The breeding season is early March through August. Egg masses are attached to underwater objects, such as the downstream sides of cobbles or other similar physical situations. Thus, potentially suitable breeding conditions might occur within the ST-1 and PT-10, into which ST-1 flows. The project would result in an increase in flow in PT-10, which could render some microsites less suitable for the attachment of egg masses, but would also make other microsites, specifically ones in the wider portions of the channel, more suitable. Therefore, impacts within PT-10 are judged to be a less-than-significant impact. If FYF occurs within ST-1, discharge of treated water into this feature would result in alteration of flow regime that could reduce its suitability as breeding habitat for the species, which is a potentially significant impact. Mitigation Measure 4C, which would survey for and avoid impacts to FLF, would reduce this impact. In the event of modification of project design so that the treated water discharge point is further downstream, at PT-8, the impact would be less than significant and no mitigation would be warranted.

Western Pond Turtle

Western pond turtle is highly aquatic during most of the year, but emerges from the water to excavate nests in nearby uplands, in which it lays its eggs before returning to the pond or stream. Suitable habitat for pond turtle is present in Perennial Ponds 1 and 2 (PP-1 and PP-2). The December 2014 biological inventory report notes the suspected presence of western pond turtle within PP-1. Subsequent incidental observations onsite have resulted in definitive identification of this species. Only one individual has been observed, though at least one other is almost certainly present. In addition, a disturbed turtle nest was found about 500 feet north of the pond.

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PP-2 is located very close to proposed construction. If it is inhabited, and if construction occurs during the season that nests with unhatched eggs might be present, destruction of nests could occur. It is difficult or impossible to reliably survey for nests once they are created, so, if pond turtles are present in this pond, effective mitigation would depend upon impeding any turtles that are present from entering construction areas.

Nesting times for western pond turtles vary in different locations where they have been studied (which do not include western Nevada County), possibly ranging from late April to early August, but the nests are then present for several to many months before hatchlings emerge. Under the circumstances of the Project Area, it is infeasible and ineffective to survey for nests, which are well concealed (at least from human observers). Also, the project entails potential for impact on adults. Accordingly, suggested mitigation measures are not seasonally dependent, but would apply no matter when construction occurs. Mitigation Measure 4D is therefore recommended to reduce potential impacts on western pond turtle to a less-than- significant level.

Bats

The Project site includes habitat types, such as pine forest, that are common in the region and provide potential roosting sites during the season of bat activity. The site also includes one old mine adit which is probably too small and water-filled to be a suitable roost or hibernation site; the adit would not be destroyed or blocked by Proposed Project actions, and on the contrary would, if anything, become less unsuitable with the anticipated Project consequence of reduction of the amount of water within the adit. There are no other potentially suitable hibernation sites (caves, buildings, and so on) that would be affected by the project. The site provides suitable foraging habitat for all five species, but even if any of them are present in the area and forage within the site, the potential impact from alteration of foraging habitat would be either none or less than significant depending on species.

Pallid Bat

In addition to the qualification provided above for roost sites, roost sites for pallid bat are also characterized by limited middle and lower canopy vegetation/branches, and by easterly (dead trees) or southerly (live trees) aspect, that is, with better exposure to the sun. This suggests that tree roosts during the active season are selected for warmth, especially in the morning. If pallid bats are selecting tree roosts that are warmer, they probably do not continue to roost in them during the winter, but instead relocate to roosts within caves, tunnels, or rock crevices, where temperatures remain much more stable during the colder seasons. Pallid bats are not know to migrate long distances, but instead move relatively short distances to hibernacula. As is known for many bat species, pallid bats are believed to be extremely sensitive to disturbance of roosts.

There is potential for pallid bats to roost within larger trees in the Project Area during the warmer seasons, and removal of occupied roost trees could result in an adverse impact. This impact would be less than significant with implementation of Mitigation Measure 4E, which would reduce potential impacts to pallid bats through surveys and avoidance.

Spotted Bat

The spotted bat occurs in meadows near, or openings within, conifer forests, but roosts only in crevices in sizeable rock cliffs, which do not occur within the North Star Project Area. The site is within the geographic range of spotted bat, and a small area of marginally suitable foraging habitat (grassland opening in forest) is present, but alteration of this would be a less-than- significant impact, especially in light of the large areas of meadow, pasture, and other grassland found in the project region. Therefore, there is no potentially significant impact that would reasonably be anticipated from the project. North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 46 of 113 July 9, 2015

Townsend’s Big-eared Bat

This species is a colonial cave roosting bat, which may also use old mine workings and buildings, at least temporarily. Roosts of Townsend’s big-eared bat are large but enclosed spaces with a fairly substantial opening at least 6 inches high and 12 inches wide, and most are much larger. The actual roosting microsites are at least 3 feet, generally 8 to 16 feet, above the ground, allowing the bats to drop into flight. Most roost sites are entirely dry. These roost site details confirm that no features within the Project Area, specifically the “adit” from which water flows perennially, are current suitable for roosting use by Townsend’s big-eared bat. The adit has a marginally large enough opening, but does not attain the larger interior dimensions required by the species, and it is filled with water, which is unsuitable.

Therefore, the project would not have any significant impact on Townsend’s big-eared bat, and effects (if any) on foraging, if the species roosts nearby but uses the site for foraging, would be less than significant.

Western Mastiff Bat

This species is regarded as roosting in colonies, exclusively in crevices in rock cliffs. It is not known with certainty whether western mastiff bat hibernates or not, or merely goes into torpor daily, mobilizing to forage at night when temperatures are above about 40 F. This would permit nearly year-round occupancy of habitat in the vicinity of Grass Valley. Thus, the Project Area falls well within the geographic and ecological range of the species, but since there are no features within the site that provide suitable roosting habitat, the project would not have a significant impact on western mastiff bat; foraging habitat (if the species is even present in the region) would not be substantially altered.

Western Red Bat

This species roosts exclusively in trees and shrubs, specifically hanging from branches or leaves rather than under bark or in the interior of hollow or cracks. Western red bat preferentially forages in riparian areas. Thus, the Project Area seems ecologically to be potentially suitable. However, a comprehensive study by Pierson et al. (2006), including considerable field survey work, provided detailed occurrence records and range maps showing that the species distribution is mostly confined to the Central Valley plus a small range extensions beyond the Valley along the northern Sacramento River and in the Stanislaus and Merced river valleys well south of Sacramento. Accordingly, the best available information is that the Project Area is outside the range of this species, and there is no potential for impact upon it from the Proposed Project.

Common Plant and Animal Species

Loss of limited numbers of common species of plants or animals is not a significant impact under current CEQA guidelines pertaining to biological resources. However, the Migratory Bird Treaty Act (MBTA) and California Fish and Game Code (FGC) §3513 prohibit take of migratory birds, which is defined to include destruction of active nests (presumed to contain eggs or nestlings). Compliance with the MBTA requires that no grading, brush clearing (mechanized or otherwise), or tree removal occur during the nesting season without a nesting bird survey that confirms that no occupied nests are present, or contingent mitigation actions if nests are present. In the case of tall coniferous trees, it is not scientifically possible to ensure that small bird nests high in the canopy can be found by a survey carried out from the ground. Thus, in coniferous habitat with trees >24 inches dbh, tree removal must occur outside the nesting season to ensure compliance with the MBTA. In western Nevada County, the nesting season for raptors and owls extends from sometime in the winter (in the case of great horned owl) through mid-August. North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 47 of 113 July 9, 2015

Smaller migratory birds begin nesting in May and continue to occupy nests until as late as August 15 (in the case of some species that raise two broods per year; depends upon habitat and species in question). Mitigation Measure 4F requires a nesting survey prior to any disturbance to either offset or avoid impacts to potentially nesting raptors and migratory birds.

As discussed above, the project would result in potential impacts on yellow warbler, RLF, FYF, western pond turtle, pallid bat, and nesting raptors and migratory birds, but these impacts would be less than significant with mitigation with the implementation of Mitigation Measures 4A-4F below.

Impact Discussion 4b-d: Would the Proposed Project have a substantial adverse effect on any riparian habitat or other sensitive natural community identified in local or regional plans, policies, regulations, or by the California Department of Fish and Game or US Fish and Wildlife Service? Would the Proposed Project have a substantial adverse effect on any riparian habitat or other sensitive natural community identified in local or regional plans, policies, regulations, or by the California Department of Fish and Game or US Fish and Wildlife Service? Would the Proposed Project result in a substantial reduction in the extent, diversity, or quality of native vegetation, including brush removal for fire prevention and flood control improvements? Would the Proposed Project have a substantial adverse effect on federally protected wetlands as defined by Section 404 of the Clean Water Act (including, but not limited to, marsh, vernal pool, coastal, etc.) through direct removal, filling, hydrological interruption, or other means?

Within the 70-acre Project Area, approximately 0.49 acre is riparian wetland, 0.55 acre is freshwater emergency wetlands, 0.1 acre is mixed fen wetlands, and there are two perennial ponds, one covering 0.17 acre and another 0.03 acre. Perennial tributaries and seasonal tributaries to Wolf Creek are also located through the Project Area. Figure 8 shows the locations of these features (Ecosynthesis Scientific & Regulatory Services 2014).

No direct wetland impacts (defined herein as excavation or placement of fill within wetlands or other waters), nor removal of non-wetland riparian habitat, is proposed. Non-wetland waters as those wetlands of uncertain hydrologic connection which may not be considered “Waters of the U.S.” by the U.S. Army Corps of Engineers. The Proposed Project is intended to result in the capture of all of the water that presently emerges from the Drew Tunnel, as well as the water that emerges from the adit and pipe culvert as the perennial tributaries PT-8 and PT-9. This result facilitates improvement of water quality entering Wolf Creek. However, it would also result in a reduction in the existing area of 0.048 acre of what the project biologist has identified as non-wetland waters. Mitigation Measure 4G would require the purchase of 0.048 acre of credit for perennial non-wetland surface waters to reduce potential impacts associated with the reduction of non-wetland waters.

One of the Mixed Fen Wetlands, MFW-2, is believed to have some subsurface connection to the water that flows out of the adit and pipe culvert. Therefore, it is possible that this feature might be affected by the pumping of this water, and would become drier, or possibly even lose sufficient hydrologic support and no longer be a wetland. Although the project as a whole would create a much greater amount of wetlands at the proposed wetland water treatment pond, the impact on MFW-2 would constitute a loss of wetland area of 0.025 acre due to indirect effects, which would be considered a potentially significant impact. This anticipated impact would be reduced with Mitigation Measure 4G, which would require the purchase of 0.025 acre of credit for seasonal wetland credits from an approved wetland mitigation bank or an in-lieu fee for Nationwide Permit impacts.

For decades, the perennial portion of PT-10 has been conducting significant perennial flows (seasonally varying from about 0.5 to 2 cubic feet per second (cfs) from the terminus of Allison Ranch Canal, plus much greater flows from stormwater runoff from the watershed. The project biologist considers this segment to be erosionally stable. The perennial flows only fill a portion of the channel’s cross-sectional North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 48 of 113 July 9, 2015 area, so there is sufficient channel stability and excess flow capacity to receive additional flows without substantial adversely erosion impacts. However, discharge of treated water would add about 2 cfs, or sometimes more during rainy periods or parts of the year when flows of the groundwaters that will be treated are higher, to the flow in ST-1 and PT-10). The discharge of treated water could result in erosion of the ST-1. Mitigation Measure 4H would reduce potential erosion into ST-1 by evaluating the channel dimensions and gradients and implementing outfall design recommendations as necessary.

Habitat degradation could also result from construction within 100 feet of wetlands, perennial water bodies, or riparian areas. At the nearest point, construction of the proposed wetland pond would approach within 10-20 feet of the closest point of a riparian wetland; pipeline construction also approaches close to a perennial tributary, but only over a short distance. Construction activity is proposed uphill of the wetland area; therefore, sediment from disturbed soil could enter the wetland and downstream waters, resulting in a potentially significant impact. Additionally, some project facilities would be constructed within 100 feet of wetlands, riparian areas, and/or perennial water bodies, though not within the jurisdictional limits of any wetland or other water. The potential for sediment generation and transport into wetlands or other waters could result in both short-term, construction-related impacts and long-term, operational sedimentation impacts. To protect against these sedimentation and erosion impacts, Mitigation Measure 4I requires temporary sediment controls prior to grading or ground disturbance.

The presence of two highly invasive non-native species (Armenian blackberry and Scotch broom) means that disturbed soils are potentially subject to colonization by these weeds during the first year or two after construction, which could result in failure to develop the dense vegetation that is necessary to control erosion in some critical areas, most particularly the berms containing the wetland pond and other facilities. Mitigation Measure 4J requires revegetation of disturbed areas within 100 feet of wetland or aquatic habitats to reduce this impact as well as potential long-term erosion impacts.

With implementation of Mitigation Measures 4G-4J as described above, impacts related to wetlands and degradation of riparian habitat would be less than significant with mitigation.

Impact Discussion 4e-f: Would the Proposed Project interfere substantially with the movement of any native resident or migratory fish or wildlife species or with established native resident or migratory wildlife corridors, or impede the use of native wildlife nursery sites? Would the Proposed Project conflict with any local policies or ordinances protecting biological resources, such as a tree preservation policy or ordinance?

A number of local policies and ordinances that protect biological resources exist, including policies protecting deer habitat; rare, threatened, and endangered species and their habitats; timber resources; landmark and heritage trees and groves; and watercourses, wetlands, and riparian areas (Nevada County 2012). Impact Discussion a-d above evaluates these issues, with the exception of impacts to deer habitat. The Project Area does not contain any protected trees such as heritage or landmark oaks, or oak woodlands. The Project Area falls within the Motherlode herd, which is a unit of generally resident deer that may move limited distances seasonally, but are not fully migratory between non-overlapping summer and winter ranges. Consequently, regulatory goals and policies pertaining to protection of migratory routes and critical summer (fawning) and winter ranges are not applicable to the Area. Furthermore, based upon the minimal use of the Area by resident (not migratory) deer, the project would not be expected to have significant impacts upon black-tailed or mule deer. Therefore, the proposed would not conflict with any local policies or ordinances protecting biological resources, and this impact is less than significant.

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Impact Discussion 4g: Would the Proposed Project introduce any factors (light, fencing, noise, human presence and/or domestic animals), which could hinder the normal activities of wildlife?

The Proposed Project could temporarily result in light sources, noise, and human activity; however, construction activities generally occur during daylight hours, and project construction would result in temporary noise and visual disturbance. After construction is complete, there would be no lighting and minimal noise, so there would be no permanent impact in these respects on habitat or wildlife values. Mitigation measures that reduce these temporary impacts on common and special-status species are also provided in Mitigation Measures 4F-4J. Therefore, this impact would be less than significant with mitigation.

Mitigation & Residual Impact

To offset the potential impacts to biological resources associated with the project construction and operation, the following mitigation measures shall be required:

Mitigation Measure 4A: Avoid and reduce impacts to nesting yellow warbler. In the event that tree removal and/or operation of mechanized equipment of any kind is proposed to be newly initiated or initiated after one weeks of non-activity within 100 feet of RW-2 or FEW-2 (specific locations identified in the Biological Inventory Report and Habitat Management Plan prepared by Ecosynthesis, dated December 19, 2014) between May 1 and July 1, surveys for nesting yellow warblers shall be conducted in any suitable nesting habitat that lies within 100 feet of all locations where equipment operation would occur. Surveys shall be conducted between 7 and 14 days prior to initiation of construction, and during morning hours only. If adult yellow warblers are detected during the survey (nest sites may not be identifiable), no equipment operation shall occur within 100 feet of the suitable nesting habitat until it is conclusively determined that no nest is present, or the nest is identified and young have fledged. This measure shall be noted on the grading and construction plans for this project.

Timing: Prior to issuance of the grading permits and improvement plans between May 1 and July 1 Reporting: Agency approval of permits and plans Responsible Agency: Planning Department

Mitigation Measure 4B: Avoid and reduce impacts to California red-legged frog (CRF). Prior to issuance of any grading or improvement permits, the project applicant shall conduct a habitat suitability assessment according to USFWS guidelines and submit this assessment for USFWS concurrence. If the assessment determines that suitable breeding habitat occurs within one or more wetlands or other waters within the site, the project applicant shall hire a qualified, County-approved biologist to conduct a full protocol survey for the species itself, according to USFWS protocol and seasonal recommendations for the Project Area. If the survey detects presence of CRF within any water bodies of the Project Area, the project shall consult with USFWS to establish protective measures that would be implemented during construction to minimize the potential for loss of individual CRF. Such measures might include, but would not be limited to, installation of barrier fences to impede CRF from moving from occupied water bodies into areas of construction activity, minimization of the creation of temporary refuge sites in uncovered trenches or basins, and monitoring by a qualified biologist during construction activities. In the event that consultation with USFWS is not completed within a reasonable time period, such as six months, of submittal of the protocol survey results, the mitigation measure would be considered to have been satisfied if the project implements measures that have been accepted for other construction projects with similar circumstances. It is recommended but not required that the project applicant and/or the project biologist also obtain an incidental take permit if potential CRF breeding habitat in the Project Area is determined to be occupied. An incidental take permit protects the owner and contractor against penalties under the Endangered Species Act if individuals of a listed wildlife species are harmed despite North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 50 of 113 July 9, 2015 the implementation of mitigation measures, and allows for capture of individuals if necessary to facilitate definitive identification.

Timing: Prior to issuance of the grading permits and improvement plans Reporting: Agency approval of permits and plans Responsible Agency: Planning Department and USFWS

Mitigation Measure 4C: Avoid and reduce impacts to foothill yellow-legged frog (FYF). If the treated water from the project treatment ponds is discharged at PT-8 (specific location identified in the Biological Inventory Report and Habitat Management Plan prepared by Ecosynthesis, dated December 19, 2014), no mitigation is required. If the treated water is discharged at ST-1 (location identified in the Biological Inventory) as currently proposed, or any other location, then the project shall survey for FYF during the appropriate season to detect breeding individuals or egg masses (likely from March through June, but may require more than one visit depending upon weather during the year when the survey occurs). If the species is not detected, no further mitigation is required. If it is present, the applicant shall reroute the treated water discharge to unnamed tributary PT-10 (location identified in the Biological Inventory).

Timing: Prior to issuance of the grading permits and improvement plans Reporting: Agency approval of permits and plans Responsible Agency: Planning Department

Mitigation Measure 4D: Avoid and reduce impacts to western pond turtle. Prior to initiation of ground-disturbing activities in the area of the pond (PP-1) (specific location identified in the Biological Inventory Report and Habitat Management Plan prepared by Ecosynthesis, dated December 19, 2014), construction supervision staff and workers shall be educated regarding the presence of western pond turtle and the measures to be taken to minimize potential impacts and on procedures in the event that an individual pond turtle or nest is discovered during construction. A biological monitor shall be present during pipeline construction within 600 feet of the pond. In addition, the pipeline trench should be covered at the end of each work day to prevent turtles from falling in and potentially becoming trapped, and it shall be inspected by the monitor each morning. If any pond turtles are discovered within the pipe trench, they shall be captured and relocated to the pond. In the event that a pond turtle nest is inadvertently disturbed during construction, any undamaged eggs shall be salvaged and transferred to a wildlife rescue facility for rearing and release into the wild.

Timing: Prior to issuance of the grading permits and improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department

Mitigation Measure 4E: Avoid and reduce impacts to pallid bat. If trees are to be removed for project construction at any time after March 30 and before September 16, acoustical surveys for the presence or absence of pallid bat shall be performed by a biologist with experience in this type of survey. If pallid bat is not detected within the project site, then no further mitigation is required. If pallid bat is detected acoustically within the site, then no trees larger than 24 inches dbh (“potential roost trees”) shall be removed until either follow-up acoustical surveys demonstrate that pallid bats are no longer foraging within the site; or each potential roost tree that is either designated to be removed or is located within a 50 foot radius of a tree to be removed is determined definitively not to contain a hollow suitable for pallid bat roosting use; or until the period of September 16 to March 30, during which trees of any size may be removed without other mitigation for potential impacts on pallid bat.

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 51 of 113 July 9, 2015

Mitigation Measure 4F: Avoid and reduce impacts to nesting raptors and migratory birds. If feasible and where possible, the applicant shall conduct tree removal and initial grading between August 15 and October 15. Alternatively, larger trees may be felled in late fall or winter and left on the ground for removal during the following construction season. If vegetation removal (tree removal or brush mastication) or ground surface disturbance (any form of grading) are to occur between May 1 and August 15, the applicant shall hire a qualified biologist to conduct nesting bird surveys, which shall occur between 7 and 14 days prior to initiation of construction, between dawn and 11 AM for small birds and avoiding mid-day for all birds. Survey work shall cover all habitat within 100 feet of vegetation removal or ground disturbance, or a greater distance in the case of raptor/owl survey: a distance of 500 feet from the limit of disturbance. In the event that nests are identified, temporary non-disturbance zones shall be the same width as the survey buffer (100-500 feet, depending on the species found to be nesting); a revisit by the biologist, with confirmed observations of fledglings in the nest vicinity, shall also be required prior to vegetation removal or soil disturbance, unless this were to be delayed past August 15.

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department

Mitigation Measure 4G: Compensate for potential wetland loss. The project shall purchase 0.048 acre of credit for perennial non-wetland surface waters and 0.025 acre of credit for seasonal wetland at an approved mitigation bank with a geographic service area including the site, or shall make a payment analogous to an in-lieu fee payment for nationwide permit impacts at an approved mitigation bank, for 0.048 acre of non-wetland waters and 0.025 acre at the rate applicable to seasonal wetland at the time that the project is initiated. In the event that the acreages of the three features in question are modified in the course of verification of the jurisdictional determination by the U.S. Army Corps of Engineers, the acreages of mitigation shall be correspondingly adjusted.

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department, US Army Corps of Engineers

Mitigation Measure 4H: Reduce potential erosion into the Seasonal Tributary ST-1. Prior to issuance of grading or improvement permits, the project shall compare the channel dimensions and gradients between ST-1 and PT-8 (the latter being known to be stable under flow regimes similar to the proposed discharge) (specific locations identified in the Biological Inventory Report and Habitat Management Plan prepared by Ecosynthesis, dated December 19, 2014) to determine whether the Seasonal Tributary segment has the capacity to conduct discharge flows year-round without resulting in significant erosion. For this purpose, hydrologic modeling of the channel watershed is not required. Comparison of channel dimensions and gradient between the seasonal and perennial segments suffices because the perennial segment provides an empirical standard of a channel in the same materials that remains stable when subjected to the same general flow regime (sustained wet-season flow from the NID canal being nearly as much as the flow of treated water). Once comparison has been, the following actions shall be taken:

a. If the Seasonal Tributary is determined to be stable under anticipated flows, no further actions are required other than the Outfall Design recommendations described below. b. If the Seasonal Tributary is not reasonably expected to remain stable, the recommended course of action would be to pipe the treated water down to a point where it can be discharged into the lower, perennial portion of the tributary immediately above or below the existing culvert. At that point, the recommendations pertaining to Outfall Design would be implemented. c. Outfall Design: In either case, the outflow structure shall be constructed as a wide rock-lined outfall without a single concentrated flow point (D50 of 4-6 inches; width: as wide as surrounding North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 52 of 113 July 9, 2015

topography permits, or up to 8 feet wide at the level annual maximum flow), so as to disperse the outflows and minimize the potential for point erosion. Total width of the discharge conveyance includes “banks” outside the flow width. The outfall shall be constructed entirely outside jurisdictional limits and shall be feathered into the existing topography.

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department

Mitigation Measure 4I: Reduce construction and operational sediment conveyance to Project Area wetlands and other waters. Sediment containment (temporary BMPs) shall be installed prior to the arrival of any excavating equipment other than that used to install the BMPs. The central feature of temporary BMPs for construction of the proposed wetland pond is a silt fence installation between that project element and the wetlands and waters to the northwest. Straw rolls or wattles will not be effective and are not an acceptable BMP for sediment control in this location. Silt fencing shall be installed as follows and these criteria shall be included as a note on grading plans:

. At a minimum, the silt fencing system shall extend from the small topographic rise southeast of Perennial Pond PP-2 past the northern terminus of RW-2 (specific locations identified in the Biological Inventory Report and Habitat Management Plan prepared by Ecosynthesis, dated December 19, 2014). . To provide sufficient sediment capacity and to prevent the possibility of concentrating flows to a degree that exceeds the ability of silt fence and its supporting stakes to contain water without collapsing, the silt fence system shall be constructed in a series of short runs, each terminating in an upwardly curved downhill end forming a mini-detention area. . Silt fence shall be installed keyed into a 6-inch trench and over-backfilled. Due to the rocky nature of some of the soils present on site, a stockpile of screened material (with larger angular rocks that would damage the fabric removed) may be required for use as silt fence trench backfill. . If rocky conditions prevent satisfactory keying in of the toe of the silt fence, it may be rolled into coir netting and a seal constructed at the soil surface from suitable erosion control fibers such as a separate layer of folded coir netting. Any such deviation from the trenching specification should occur only under the Project Engineer’s authority (not by the implementing contractor alone) in consultation with a Certified Professional in Erosion and Sediment Control (CPESC) or other qualified individual with field experience monitoring BMP installations under extreme precipitation conditions. . Silt fencing shall be fabric only (no metal wire, which interferes with achieving a good join with the soil surface and, in the very constrained space that is the case for the present project, presents nearly insurmountable difficulties in removal without destabilizing the detained sediment. . Support stakes shall be at a maximum spacing of 10 feet, and less than that at the points where water is expected to be concentrated. Standard wooden stakes may not be effective in the site’s rocky soils; substitution or supplementation by metal rods may be necessary. . Additional support in the form of straw bales placed on the downhill side of the silt fencing at key locations is recommended. . Silt fence shall be monitored, maintained, and repaired as necessary throughout construction and revegetation. It shall not be removed until the contained sediment behind it has been revegetated with a minimum absolute cover of 70 percent. . If any soil is to remain exposed during the rainy season, weather forecasts shall be monitored daily, and, whenever any amount of rainfall greater than ¼ inch is expected within the next 24 hours, any loose exposed soil shall be covered with plastic sheeting, adequately weighted over its entire surface to prevent it from blowing loose during the winds that frequently precede or accompany rainfall in the project region. Straw wattles or erosion control blankets are not recommended for use even in areas other than the one critical silt fence installation described in detail above. However, if they are used, they shall be ones fabricated entirely of biodegradable North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 53 of 113 July 9, 2015

materials; no plastic. Monofilament netting entails significant risk of wildlife entrapment. If rolled products are to be used, coir netting is recommended over all other alternatives. Provisions related to equipment maintenance, storage of materials, and stabilized access points that are included in the Stormwater Pollution Prevention Plan shall be implemented and monitored as specified therein. . Additional sediment controls may also be required under the Stormwater Pollution Prevention Plan subject to approval by the Central Valley Regional Water Quality Control Board.

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department, Central Valley Regional Water Quality Control Board

Mitigation Measure 4J: Permanently revegetate disturbed area to avoid indirect impacts on nearby wetlands and other waters.

1. Soil management. The upper layer of existing soil shall be salvaged and stockpiled for use in construction of facility outslopes, on which it is important for revegetation to result in a thick stand of self-sustaining vegetation to preclude the need for costly maintenance and repair. The depth of the salvage shall be a minimum of six inches, or up to 12 inches depending on soil testing and calculation of the volume needed to construct the perimeter berms. If the soil stockpile is to be retained during the rainy season, it shall be seeded with the seed mix specified below. Vegetation resulting from seeding the stockpile will enhance the rate at which final revegetation occurs. The outer soil layer on slopes to be revegetated (such as outslopes of the proposed pond) shall not be compacted to a higher degree than 85% at optimum moisture content (OMC). If there is an engineering necessity for greater compaction of the interior, then an additional outer layer shall be installed for revegetation. Optionally, this may require creating excavator divots or subgrade benches at a one foot vertical interval to ensure that the revegetation soil layer does not slump when wet. Revegetation within the site shall not entail use of any high-nutrient amendments such as fertilizer of any nature including slow-release and biologically based fertilizers. Compost may be employed if it does not contain manure supplements and if it is tilled in when the final soil surface is established.

2. Hydroseeding and mulch. Hydraulic erosion control application shall occur as soon as possible following completion of ground disturbing activities. If hydroseeding occurs when the soil surface is dry, mulch often fails to adhere and peels off at the first rainfall. Therefore, if conditions are dry, hydraulic applications shall occur in two passes: one of water and seed, the other of hydromulch. If the surface materials are rough (which is desirable from the perspective of capturing seed and rainfall and reducing sheet flow velocities), mulch application shall be from two directions so that full coverage is achieved. Hydromulch of the outslopes of the facilities shall employ bonded fiber matrix. Hydromulch used in other areas may be of any other kind as appropriate to manufacturer’s specifications. Seed mix shall be as specified below, as based on what presently grows on site and species that are successful (not not invasive) in the area. Seed specification is subject to revision by a qualified revegetation specialist based upon any additional soil observations or laboratory data that may be obtained:

. Vulpia (Festuca) myuros (foxtail fescue), 5 lbs PLS/acre . Festuca sp. (perennial fescue – prefer red, meadow, or hard fescue in that order), 3 lbs PLS /acre . Bromus hordeaceus (Blando brome), 7 lbs PLS /acre . Dactylis glomerata (orchard grass) and/or Festuca arundinacea (tall fescue), 1 lbs PLS /acre either . species or combined . Elymus glaucus (blue wild-rye), 3 lbs PLS /acre North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 54 of 113 July 9, 2015

. Either or both of the following nitrogen-fixing species: . Lupinus nanus (sky lupine), 4 lbs PLS /acre . Trifolium hirtum (rose clover), 2 lbs PLS/acre . Ceanothus prostratus var. prostratus (squaw carpet), 20 seeds/square foot on outslopes or other slopes at 3:1 or steeper.

Lower application rates are still beneficial if insufficient seed supply is available. Seed pretreatment to enhance germination is required. If other seed sources are lacking, squaw carpet shall be the preferred backfill species.

Seed shall be delivered in separate bags, not mixed, and each bag shall be labeled with species, origin or cultivar name, germination testing information and date, and weed seed content. Seed that is unlabeled or lacks any of the labeling listed above shall be rejected. Weed seed content shall not exceed 1 percent and shall not include any species of Melilotus or any species with a Cal-IPC rating of “High” in any amount. Any seed lot not meeting these weed seed criteria shall be rejected.

3. Revegetation maintenance. Revegetated areas shall be monitored at least twice each year (May and August are suggested) for the first two years after construction is complete, and every individual of Armenian blackberry and Scotch broom that is found shall be eliminated from areas where the revegetation is critical to erosion control. Particular attention shall be paid to the berms containing the wetland pond and other facilities. Due to the close proximity of aquatic habitat, mechanical means are preferred; specifically, plants shall be uprooted rather than merely cut. Once desired revegetation species have established a dense stand of erosion-controlling vegetation, invasion by weeds may still occur, but would not be expected to jeopardize the bioengineering performance of the revegetation.

Timing: Prior to issuance of the grading permits or improvement plans and twice a year for two years Reporting: Agency approval of permits or plans Responsible Agency: Planning Department

5. CULTURAL RESOURCES

Less Than Potentially Less Than Significant Significant Significant No Impact Would the Proposed Project: with Impact Impact Mitigation a. Cause a substantial adverse change in the significance of a historical resource as defined in Section 15064.5 of the  CEQA Guidelines? b. Cause a substantial adverse change in the significance of an archaeological resource pursuant to Section 15064.5 of the  CEQA Guidelines? c. Directly or indirectly destroy a unique paleontological  resource or site or unique geologic feature? d. Disturb any human remains, including those interred  outside of formal cemeteries?

North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 55 of 113 July 9, 2015

Existing Setting

The information for this section of the Initial Study is based on the Class I Archaeological Survey and Class III Archaeology Survey prepared by Sean Jensen, dated August 20, 2013 and February 27, 2015, respectively (Jensen 2013 and Jensen 2015).

Prehistoric Context

Initial human entry into California occurred between about 10,000 and 6,000 BC, and early peoples in the area subsisted on hunting and lake exploitation. These early cultural assemblages were followed by an increase in population density after about 7,500 years ago. From about 6,000 to 3,000 BC, the transition to a less specialized foraging strategy coincides with a climatic change to generally drier conditions, which resulted in the drying of many of the West’s rainfed lakes. Hunting and gathering populations of this period were small, mobile groups that focused increasingly on diverse environmental settings. By about 3,000 to 1,000 BC, the broad regional patterns of foraging subsistence strategies had given way to more intensive procurement strategies, manifest in part by the establishment of year-round use of select village sites which were located along major waterways.

Between about 1,000 BC and AD 100, sociopolitical complexity and the development of status distinctions appeared. The Martis Complex emerged, which maintained a hunter-gathering subsistence strategy and a high degree of mobility. Distinctive artifact types include manos and metates used for processing food, and large projectile points and bifaces manufactured from locally available basalt.

From AD 300-500 through AD 1,800, within the northern and north-central Sierra Nevada and Central Valley, Penutian-speaking Native American peoples arrived, including those who occupied lands within and around the project area at the time of initial contact with European-American populations – the Nisenan. These Penutian-speaking arrivals may have begun to displace the Martis populations, especially along the major river systems. The Penutian arrivals more extensively used bulbs and other plant foods, more intensively processed animal and fishing products with mortars and pestles, and produced more bows and arrows and associated small stemmed- and corner-notched projectile points.

The Nisenan, also known as “Southern Maidu,” occupied the drainages of the southern Feather River and Honcut Creek in the north, through Bear River and the Yuba and American River drainages in the south. Villages were frequently located on flats adjoining streams, and were inhabited mainly in the winter as it was usually necessary to go out into the hills and higher elevation zones to establish temporary camps during food gathering seasons (i.e., spring, summer and fall). As with all northern California Indian groups, economic life for the Nisenan revolved around hunting, fishing and the collecting of plant foods. These people were very sophisticated in terms of their knowledge of the uses of local animals and plants, and of the availability of raw material sources that could be used in manufacturing an immense array of primary and secondary tools and implements.

Historic Context

European Americans began arriving in substantial numbers in the mid-1820s, most notably with the trapping expeditions of Jedediah Smith. However, the European American incursion with the greatest impact on Native American population and culture and the environmental structure of this area occurred immediately following the discovery of gold at Coloma in 1848, which initiated the Gold Rush of 1849.

In early 1849, the first settlement in Nevada County was established east of Smartville near Pleasant Valley to provide supplies for miners. In August 1849, a Dr. Saunders built a cabin on Badger Hill at the eastern edge of present day Grass Valley, and shortly thereafter settlers began moving into the resource- rich region. A sawmill and a post office, called Centerville, were established shortly thereafter, and on August 20, 1852, the name was replaced by the title Grass Valley. Initial mining of the region was North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 56 of 113 July 9, 2015 conducted almost entirely via surface placer techniques, but drift mining began in the 1850s and continued until about 1900. The most productive mines in the region were the consolidated North Star and Empire mines. These mines operated for more than a century, yielding over $80 million. The longest vein extends for nearly two miles, and the longest shaft extended nearly 7,000 feet, with 4,000 feet of vertical depth. Mining activities slowed and intensified over the years but were officially suspended by the federal government during World War II, leading to the failure of many of Nevada County's mines. Those remaining that did resume after World War II closed by 1956.

Logging and ranching represent additional historic themes for this area within the southern portion of Grass Valley. As with the earlier mining emphasis, activities associated with logging and ranching have also adversely affected the local cultural resource base, although typically with somewhat less severe impacts than actions associated with the early days of gold mining.

Impact Discussion

Impact Discussion 5a-d: Would the Proposed Project cause a substantial adverse change in the significance of a historical resource as defined in Section 15064.5 of the CEQA Guidelines? Would the Proposed Project Cause a substantial adverse change in the significance of an archaeological resource pursuant to Section 15064.5 of the CEQA Guidelines? Would the Proposed Project directly or indirectly destroy a unique paleontological resource or site or unique geologic feature? Would the Proposed Project disturb any human remains, including those interred outside of formal cemeteries?

Sean Michael Jensen, a qualified archaeological consultant on the California Historical Resources Information System’s list, conducted fieldwork in the Project Area in June and July 2013, the results of which are identified in the August 20, 2013 for Class I Archaeological Survey. At that time, Mr. Jensen conducted a pedestrian survey of the 100-acre study area with systematic transects spaced at 20-meter intervals. In addition, Mr. Jensen also conducted additional field work from January 17 to January 19, 2015, in order to evaluate the presence of pre-historic and historic-era resources. The results of these observations are presented in the February 27, 2015, Class III Archaeological Survey.

Both archaeological reports prepared by Mr. Jensen indicate that the entire study area appears to have been subjected to at least minimal levels of disturbance, while substantial portions of the study area have been subjected to intensive disturbance, primarily associated with past mining activities. No prehistoric resources were identified during the present pedestrian survey. The explanation for the absence of such resources is best explained by the level of disturbance to which most of the study area has been subjected. Numerous historic-era features were observed throughout the study area. In terms of number and spatial area, the majority of these observations were comprised of waste rock piles and topographic modifications (i.e., byproducts of past mining). In addition to these observations, a number of stacked rock features, shallow ditches, foundations, adits and roads were observed throughout the study area.

Records at the North Central Information Center (NCIC) at CSU-Sacramento document that approximately 85 percent of the study area has been subjected to formal archaeological survey, and that no prehistoric sites have been documented within, or adjacent to the study area. NCIC records and State of California historical resource data bases document four historical resources within the property. One of these (P-29-1457) was found to be erroneously plotted within the study area, while the second resource (P-29-1473) was recorded as four separate isolates. Both of these latter resources fail to achieve the threshold of an historic property, significant historical resource, or unique archaeological resource, and thus warrant no further consideration. The two remaining resources, P-29-896 and P-29-898, represent historical resources of significance or potential significance within the study area. During Mr. Jensen’s North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 57 of 113 July 9, 2015 additional fieldwork in January 2015, a total of six historic-era sites were identified in the Project Area. Prehistoric resources were not observed.

Mr. Jensen evaluated the historic-era sites for significance in relation to CEQA significance criteria found in Public Resources Code § 15064.5 and found the resources were not significant under the relevant evaluative criteria. No significant historical resources and no unique archaeological resources would be affected by the project, and therefore no treatment was recommended for any of the sites.

Despite these findings, the Project Area is rich in historic resources, and it is possible that additional resources could be discovered during project construction activities. Based on the findings of the archaeologist, the project would have impacts that are less than significant with mitigation, as identified in Mitigation Measure 5A, which requires construction work to stop and appropriate steps taken if cultural resources are discovered.

Mitigation and Residual Impact

To offset potentially adverse cultural or historical resources impacts associated with the construction activities, the following mitigation measure shall be required:

Mitigation Measure 5A: Halt work and contact the appropriate agencies if human remains or cultural materials are discovered during project construction. All equipment operators and employees involved in any form of ground disturbance shall be advised of the remote possibility of encountering subsurface cultural resources. If such resources are encountered or suspected, work shall be halted immediately and the Nevada County Planning Department shall be contacted. A professional archaeologist shall be retained by the developer and consulted to access any discoveries and develop appropriate management recommendations for archaeological resource treatment. If bones are encountered and appear to be human, California Law requires that the Nevada County Coroner and the Native American Heritage Commission be contacted and, if Native American resources are involved, Native American organizations and individuals recognized by the County shall be notified and consulted about any plans for treatment. A note to this effect shall be included on the grading and construction plans for each phase of this project.

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department

6. GEOLOGY / SOILS

Less Than Potentially Less Than Significant Would the Proposed Project: Significant Significant No Impact with Impact Impact Mitigation a. Result in exposure to or production of unstable earth conditions such as landslides, earthquakes, liquefaction, soil  creep, mudslides, ground failure (including expansive, compressible, collapsible soils), or similar hazards? b. Result in disruption, displacement, compaction, or over-  covering of the soil by cuts, fills, or extensive grading? c. Be located on a geologic unit or soil that is unstable, or that would become unstable as a result of the project, and  potentially result in on- or off-site landslide, lateral spreading, subsidence, liquefaction or collapse? North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 58 of 113 July 9, 2015

Less Than Potentially Less Than Significant Significant Significant No Impact Would the Proposed Project: with Impact Impact Mitigation d. Have soils incapable of adequately supporting the use of septic tanks or alternative wastewater disposal systems where  sewers are not available for the disposal of wastewater? e. Result in any increase in wind or water erosion of soils,  on or off the site? f. Changes in siltation, deposition or erosion, which may modify the channel of a river, or stream, or the bed any bay,  inlet or lake? g. Result in excessive grading on slopes of over 30 percent? 

Existing Setting

Bedrock underlying the site is primarily comprised of Triassic and Jurassic massive diabase of the Smartville Complex, with several mapped intrusions of late Jurassic to early Cretaceous quartz porphyry. The southernmost area of the site is underlain by granodiorite of late Jurassic to early Cretaceous age. The diabase and granodiorite are between several fault-bounded blocks of metasedimentary and ultramafic rocks of Paleozoic to Mesozoic age. Quaternary and older faults are present in the general site vicinity. Weathered and decomposed diabase was observed in road cuts along Allison Ranch Road and the Bypass Road during the field reconnaissance. The diabase in this area typically decomposes to dark reddish brown silty clay (CL) with sand (residual soil) near the ground surface or in outcrops (MWH 2014).

These soil series and map units cover most of the Project Area: Hoda sandy loam (5 to 9 percent and 9 to 15 percent slopes), Sites loam (2 to 9 percent and 15 to 30 percent slopes), Sites very stony loam (15 to 30 percent slopes). Small areas of Placer diggings, Musick-Rock outcrop, Alluvial land (loamy), and Josephine-Mariposa complex are found, almost exclusively in locations not within the Project Area footprint, or which are crossed by pipeline construction in an existing road right-of-way. The majority of the area where construction would occur is Hoda sandy loam (MWH 2014).

Field observations revealed piles of angular rocks in several places within the Area, not within mapped Placer diggings soils. These did not appear to be natural rock outcrops and were provisionally interpreted as being deposits of excavated materials or mined waste rock. The topography of the southern part of the site, where treatment facilities are proposed to be located, appear to be disturbed, and two large areas support grassland and weedy vegetation instead of the conifer forest that grows everywhere else around them. Accordingly, it is probable that the existing soil survey mapping does not accurately represent the actual soils that are present in this portion of the Project Area (MWH 2014).

Impact Discussion

Impact Discussion 6a-c,e-g: Would the Proposed Project result in exposure to or production of unstable earth conditions such as landslides, earthquakes, liquefaction, soil creep, mudslides, ground failure (including expansive, compressible, collapsible soils), or similar hazards? Would the Proposed Project result in disruption, displacement, compaction, or over-covering of the soil by cuts, fills, or extensive grading? Would the Proposed Project be located on a geologic unit or soil that is unstable, or that would become unstable as a result of the project, and potentially result in on- or off-site landslide, lateral spreading, subsidence, liquefaction or collapse? Would the Proposed Project result in any increase in wind or water erosion of soils, on or off the site? Would the Proposed Project changes in siltation, deposition or erosion, which may modify the channel of a North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 59 of 113 July 9, 2015 river, or stream, or the bed any bay, inlet or lake? Would the Proposed Project result in excessive grading on slopes of over 30 percent?

A Geologic Hazards Evaluation was prepared by MWH in December 2014 for the proposed water treatment facility (MWH 2014). Other geotechnical site investigations in the Project Area that were evaluated for the MWH report include a Holdredge & Kull geotechnical evaluation from 2006 on the Allison Ranch Road landslide area; a Worthington Miller Environmental (WME) report, the 2014 Drew Tunnel Water Collection and Conveyance Alternatives Evaluation Report, which details five alternatives for water collection and conveyance for the Proposed Project; and a 2009 report entitled Allison Ranch Road Slide Area Investigation Report by MFG Investigations, which details historical and current surface features of the North Star site. This section is largely based on the Geologic Hazards Evaluation by MWH.

MWH conducted an initial geologic hazard field reconnaissance from September 2 to 4, 2014, along the pipeline alignment alternatives being considered at the time, as well a supplemental field reconnaissance on December 9 and 10, 2014, to evaluate the proposed Drew Tunnel and North Star pipeline alignments that were not previously surveyed. The purpose of the field reconnaissance was to identify geologic hazards and other features that may impact project design, including the following:

. Slope instability, landslides, and debris flows . Excessive erosion and overly-steepened slopes . Subsidence . Seepage . Shallow mine remnants (shafts, adits, etc.) . Flooding hazards . Seismic hazards

Flooding hazards are discussed in the Hydrology and Water Quality section of this Initial Study. All other issue areas are evaluated below.

Landslides and Slope Instability

The proposed North Star pipeline runs south to the Drew Tunnel pipeline alignment through an area of potentially unstable slopes with a history of landslide activity near the Allison Ranch Bypass Road (see Figures 12 through 14). Ground movement in this area can be expected. Two recent landslides, “upper” and “lower” (see Figure 13), initially occurred in April of 2006. The upper landslide damaged portions of Allison Ranch Road with up to 18 inches of vertical offset in the road. On April 17, 2006, the lower landslide, a slope below Allison Ranch Road, failed as a debris flow. Allison Ranch Road was closed for several weeks until most of the rainy season had passed, and a bypass road was installed to the west. The roadway was repaired by removing the fractured portion of the asphalt pavement, re-grading the road, and covering it with a layer of 1-inch gravel. The slide failed again during the winter of 2010/2011 and again resulted in closure of Allison Ranch Road. Slope movement should be expected to continue in this area, particularly during seasonally wet periods. The proposed Drew Tunnel pipeline alignment runs along the Bypass Road that was constructed to divert traffic during re-construction of Allison Ranch Road in 2006, and this road is considered stable as it was recently engineered and reconstructed following the landslide activity. The pipe culvert and adit features are located below Allison Ranch Road about 50 feet upslope from the lower recent landslide, but these features are not moveable as they are existing drainages from the historical mine working. The pond features are proposed in a stable area without a history of unstable slopes or landslides.

At some locations there is evidence of shallow slope creep above steep slopes. In particular, small isolated tension cracks are present above the steep cut slope immediately west of the historical road, which lies about halfway between Allison Ranch Road and Wolf Creek, and a previous pipeline alignment north of North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 60 of 113 July 9, 2015 boring B3 (see Figure 12). In addition, two zones of scarp features are present above steep cut slopes northeast of TP5 and north of TP6 (see Figure 14), within 50 to 70 feet of the proposed North Star pipeline alignment. During the recent field reconnaissance, the areas uphill and downhill of the Bypass Road were evaluated. No evidence of slope instability was observed uphill of the uppermost scarp. Nevertheless, the shallow slope creep and small shallow slumps are expected to continue as long as the adjacent slopes remain over-steepened, and the slumps may migrate uphill over time.

Due to the proximity of the proposed pipeline alignment to the approximate zone of potentially unstable slopes, the propensity for landslides to re-activate under changed conditions (such as changed loading conditions, prolonged wet periods and/or seismic events) and to migrate uphill over time, the design of the proposed Drew Tunnel pipeline alignment should account for this area of slope instability. Mitigation Measure 6A requires that the portion of the pipeline along the Bypass Road be designed to accommodate slope movement and/or stabilize the area to reduce the risk of pipeline deformation in the future.

Excessive erosion and overly-steepened slopes

Steep slopes and eroded banks are not present in the proposed pond areas.

A steep fill slope is present immediately east and downhill of the historical road (about halfway between TP3 and TP33 as shown on Figure 12). The over-steepened area is approximately 20 feet wide and extends approximately 50 feet down the hill from the historical road.

Two steep cut slopes approximately 30 feet in height, with slopes steeper than 1:1, are present immediately south of Old Landslide 2 and northwest of TP5 (Figure 13), and approximately 150 feet north of TP6 (Figure 14). The Geologic Hazards Evaluation reports that several sub-parallel scarp features were observed approximately 30 to 50 feet above both of these steep cuts and that the features range in size from small areas of tension cracking with minimal vertical displacement to obvious scarps with up to 3 feet of vertical displacement.

Approximately 1,500 feet south of the Drew Tunnel area, the roadway crosses a small drainage just northwest of TP2 (Figure 11). The east fill slope in this area is steep, with slopes ranging from 45 to 65 percent, and the east shoulder is very narrow.

At the south end of the Bypass Road, the proposed Drew Tunnel pipeline alignment crosses Allison Ranch Road and continues to the southeast along an existing road. The road runs parallel to a drainage that conveys water from the Allison Ranch NID Ditch. Just downstream from Allison Ranch Road, the drainage is narrow and incised for approximately 150 feet, with near-vertical slopes with a height of 10 to 20 feet.

In order to avoid further impacts to highly eroded or incised areas and pipeline engineering failures in these areas, Mitigation Measure 6B would require that the project be designed to maintain a 50-foot buffer from these features, and to remain in the west shoulder of Allison Ranch Road in the steep slope area of immediately northwest of TP2.

Land Subsidence

Areas of surface depressions were observed and documented at several locations in the project area. Several of these depressions are within or near the area of the proposed facilities. Depressions 2 through 6 and 10 through 12 are located near the proposed North Star pipeline alignment (Figures 13 and 14). Depressions 13 through 15 are located near the proposed Drew Tunnel pipeline alignment (Figures 14 and 15). Depressions 7 and 8 and the collapsed or backfilled New Homeward Bound Shaft are in the area of the proposed water treatment ponds (Figure 15). Some of these depressions coincide with mapped locations of shallow underground mine features. North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 61 of 113 July 9, 2015

To avoid engineering failures of the pipeline and treatment system, Mitigation Measure 6C would require that project facilities be designed to maintain a minimum 50-foot buffer from known areas of subsidence and underground mine workings.

Seepage

Seepage was observed in several locations in the debris flow of the recent landslides and was concentrated just below the scarp of the debris flow. Seepage is thought to emanate from fractures in very severely to completely weathered rock in the scarp, and continues throughout the summer and fall despite dry weather. Water also flows from the adit through the summer and fall months. A flowing seep (Spring 1) is present in the central portion of the slide area, and a mine adit with seepage is present in the southeast portion of the recent slide area (Figure 13).

Maintaining an appropriate buffer from landslide areas and mine workings where possible, as required in Mitigation Measures 6A and 6C, would reduce impacts from seepage.

Shallow Mine Remnants

The Project Area contains numerous mine remnant features, including the following as shown in Figures 11-15:

. A mine portal at the toe of the slope near Wolf Creek, east of the historical road . An adit located in the southeastern portion of the recent slide area . A collapsed inclined shaft approximately 100 feet long, 20 feet wide, and six feet deep in the southern area of the proposed treatment area . Spoils piles . Depressions . Old rock walls east of the historical road and between Allison Ranch Road and the Bypass Road

Mitigation Measure 6C requires that the project facilities maintain a 50-foot setback from mine workings where possible to reduce the potential for engineering failures during project operation. For project features that must be located within 50 feet of mine workings in order to collect or convey mine drainage, these features would be designed in such as a way as to accommodate movement due to subsidence and improve the pipeline’s resistance to deformation and construct project components to ensure safe ground conditions for construction workers and the public in the near- and long-term.

Seismic Hazards

The site is within the Foothills Fault System and is not within a designated Alquist-Priolo earthquake fault zone, nor is it located within an area delineated as a Seismic Hazards Zone. Ground rupture related to faulting is therefore not likely at the site. However, the site may experience moderate ground shaking caused by regional earthquakes.

Secondary seismic hazards include ground modifications resulting from ground shaking, such as differential compaction, liquefaction, landslides and flooding. Shaking of loosely compacted soil can induce differential soil compaction and settlement of structures constructed on loosely compacted soil. The majority of the site is underlain by soil and weathered bedrock, and the potential for differential compaction is likely low. Soil liquefaction results from loss of strength during cyclic loading, such as ground shaking. Soil susceptible to liquefaction is generally saturated, loose, uniformly-graded sandy soil. Due to the nature of the site, extensive areas of saturated, loose soils are not anticipated. The project is not located within a designated flood hazard zone, and is not near open water sources. Therefore, the risk of seismically induced flooding is low at this site. Seismically induced landslides are possible in areas of North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 62 of 113 July 9, 2015 saturated soils. The areas identified in this report as unstable slopes are also prone to seismically-induced landslides.

Mitigation Measure 6D would require the project to mitigate the effects of potential ground shaking events. Additionally, the preparation of a geotechnical evaluation as required by Mitigation Measure 6E, a standard condition of approval for all construction projects, would also help to reduce hazards from potential seismic activity on structural components by requiring the implementation of geotechnical report recommendations. The geotechnical investigation would evaluate the pipeline and structure foundation conditions and provide recommendations for compaction of any fill placed on site, and recommendations for mitigation or avoidance of liquefiable soils, if identified at the site.

Project Grading, Cuts, and Fills

According to the Project Information Questionnaire submitted by the applicant, the project would result in 29,000 cubic yards of cut and 23,800 cubic yards of fill, for a total net cut of 5,200 cubic yards. The 5,200 cubic yards of excess cut material would be placed around the proposed facilities within the areas of disturbance for revegetation purposes and used for Mitigation Measure 4J (revegetation of disturbed areas within 100 feet of wetland or aquatic habitats). Maximum depth of excavation is 14 feet and the maximum slope is 3:1 at the sedimentation pond. The Drew Tunnel Pump Station would have a 10-foot- high retaining wall. Preparation and implementation of a geotechnical report as required by Mitigation Measure 6E would help to reduce any potential impacts related to slope stability and structural integrity of retaining walls.

Erosion Potential

Construction activities during the wet weather season could result in adverse erosion impacts. Mitigation Measure 6F is recommended to limit any grading activities during the wet weather periods, and Mitigation Measure 6G is recommended to require the erosion control measures to ensure the disturbed areas outside the habitat management zone are stabilized during construction. The habitat management zone (radiating 50 feet from seasonal waters and 100 feet from perennial waters) is mitigated for erosion potential in Mitigation Measures 4H – 4J.

Mitigation Measures 6A through 6G would reduce impacts from unstable slopes, excessive eroded areas, incised drainages, ground depressions, underground mine features, seismic activity, improper disposal of cut soil, and structural stability of retaining walls, and result in impacts that are less than significant with mitigation.

Impact Discussion 6d: Would the Proposed Project result in changes in siltation, deposition or erosion, which may modify the channel of a river, or stream, or the bed any bay, inlet or lake?

The Proposed Project does not require wastewater treatment systems. Therefore, there would be no impact related to adequate soils for the disposal of wastewater.

Mitigation & Residual Impact

To offset the potential for adverse soils or erosion impacts to result from project grading and construction activities, the following mitigation measures shall be required:

Mitigation Measure 6A: Implement engineering controls and a maintenance program to reduce potential risks to the pipeline from unstable slopes along the Bypass Road alignment and in any area within the approximate zone of unstable slopes. Future slope movement may occur within and North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 63 of 113 July 9, 2015 near the approximate zone of unstable slopes as shown on Figures 4-6 of the Geological Hazards Evaluation by MWH, especially during extremely wet conditions or during seismic events. The pipeline alignment along the Bypass Road is located upslope of an approximate zone of unstable slopes where slope movement has occurred in the past. Due to the proximity of the proposed pipeline alignment to the mapped head scarp and an approximate zone of potentially unstable slopes, the portion of the pipeline along the Bypass Road and in all other areas within the “approximate zone of unstable slopes” as shown on Figures 4-6 of the Geological Hazards Evaluation by MWH shall be designed to accommodate slope movement and/or stabilize the area to reduce the risk of pipeline deformation in the future. A monitoring and maintenance program shall be developed and implemented to regularly assess pipeline performance and verify that the system continues to perform as intended. Engineering controls and a monitoring and maintenance program shall be included in the pipeline design, based on the information provided in this report. The engineering controls and monitoring and maintenance program shall be submitted to Nevada County prior to issuance of any grading or improvement plans within the designated “approximate zone of potentially unstable slopes” in MWH’s December 2014 Geologic Hazards Evaluation.

Timing: Prior to issuance of the grading permits and improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Public Works Department and Building Department

Mitigation Measure 6B: Maintain a 50-foot buffer from areas of excessive erosion and incised drainages. In order to mitigate the potential for damage to project facilities by excessive erosion or deeply incised drainages as identified in the Geologic Hazards Evaluation by MWH dated December 2014, these areas shall be avoided by maintaining a minimum 50-foot buffer from engineered features. Additionally, in the identified “steep slope” area on Figure 3 of the Geologic Hazards Evaluation immediately northwest of TP 2, the pipeline shall be located along the west lane of Allison Ranch Road. Prior to issuance of grading permits and improvement plans, the project design shall reflect this avoidance.

Timing: Prior to issuance of the grading permits and improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Public Works Department and Building Department

Mitigation Measure 6C: Maintain a 50-foot buffer from known areas of subsidence and underground mine workings where practicable. The location of known underground mine workings shall be delineated prior to issuance of grading permits and improvement plans. Where practicable, facilities shall be constructed to avoid mapped areas of subsidence and known underground mine workings by a minimum of 50 feet offset, although those construction components that must be located within 50 feet to either collect or intercept the mine waters shall be allowed. Where these areas cannot be avoided, performance standards for engineering controls shall include the following: a) site-specific ground control plans shall accommodate movement due to subsidence and improve the pipeline’s resistance to deformation; b) site-specific ground control plans shall avoid identified ground voids where possible; and c) site-specific ground control plans shall construct project components to ensure safe ground conditions for construction workers and the public in the near- and long-term.

Timing: Prior to issuance of the grading permits and improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Public Works Department

Mitigation Measure 6D: Implement seismic reinforcement measures to avoid potential impacts from seismic activity. In order to mitigate the potential for damage caused by ground shaking, prior to the issuance of grading permits and improvement plans, the project applicant shall incorporate the parameters included in the Geologic Hazards Evaluation by MWH dated December 2014 into the project design, which include but are not limited to factors of Peak Ground Acceleration (PGA), shear wave North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 64 of 113 July 9, 2015 velocity, and earthquake event return periods to ensure that all pipelines and structures associated with the project would be structurally sound and damage-resistant during potential seismic events.

Timing: Prior to issuance of the grading permits and improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Public Works Department and Building Department

Mitigation Measure 6E: Implement the recommendations of a geotechnical evaluation for project grading and structural work. Prior to issuance of grading permits and improvement plans, a geotechnical report shall be prepared by a licensed engineer and submitted to Nevada County and recommendations therein followed for all subsequent grading and structural work. The geotechnical investigation report shall provide recommendations that ensure that fill soils are compacted to CBC standards and that any liquefiable soils, if present, are accounted for in the grading design and structural specifications for the site. Performance standards shall include the following: a) all grading and structural work shall meet the performance standards of applicable CBC regulations, b) construction methods shall be used which minimize risks to structures and do not increase the risk to the site, or to adjacent properties and their structures, from the geologic hazard; c) development shall not increase instability or create a hazard to the site or adjacent properties, or result in a significant increase in sedimentation or erosion; d) site planning shall minimize disruption of existing topography and vegetation; e) excavation and grading shall be minimized to the greatest extent practicable; f) any limitations to site disturbance, such as clearing restrictions, imposed as a condition of development approval shall be marked in the field and approved by the county prior to undertaking the project; and g) a monitoring program shall be prepared for construction activities occurring in geologic hazard areas and be marked on the face of the building permit.

Timing: Prior to issuance of the grading permits and improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department and Department of Public Works

Mitigation Measure 6F: Limit the grading season. Grading plans shall include the time of year for construction activities. No grading shall occur after October 15 or before May 1 unless the Chief Building Inspector or his/her authorized agent determines project soil conditions to be adequate to accommodate construction activities.

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department and Department of Public Works

Mitigation Measure 6G: Prepare and implement an Erosion and Sediment Control Plan for areas outside the habitat management area. Prior to issuance of grading permits or improvement plans for all project related grading including road construction and drainage improvements, said permits or plans shall incorporate, at a minimum, the following erosion and sediment control measures:

a. During construction, Best Management Practices (BMPs) for temporary erosion control shall be implemented to control any pollutants that could potentially affect the quality of storm water discharges from the site. A Storm Water Pollution Prevention Plan (SWPPP) shall be prepared in accordance with California State Water Resources Control Board (SWRCB) requirements. This SWPPP includes the implementation of BMP's for Erosion Control, Sediment Control, Tracking Control, Wind Erosion Control, Waste Management and Materials Pollution Control. b. If applicable, topsoil shall be removed and stockpiled for later reuse prior to excavation activities. Topsoil shall be identified by the soil-revegetation specialist who will identify both extent and depth of the topsoil to be removed. c. Upon completion of grading, stockpiled topsoil shall be combined with wood chips, compost North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 65 of 113 July 9, 2015

and other soil amendments for placement on all graded areas. Revegetation shall consist of native seed mixes only. The primary objectives of the soil amendments and revegetation is to create site conditions that keep sediment on site, produce a stable soil surface, resist erosion and are aesthetically similar to the surrounding native forest ecosystem. d. Geo-fabrics, jutes or other mats may be used in conjunction with revegetation and soil stabilization.

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department and Department of Public Works

7. GREENHOUSE GAS EMISSIONS

Less Than Potentially Less Than Significant Significant Significant No Impact Would the Proposed Project: with Impact Impact Mitigation a. Generate greenhouse gas emissions, either directly or indirectly, that may have a significant impact on the  environment? b. Conflict with any applicable plan, policy or regulation of an agency adopted for the purpose of reducing the emissions of  greenhouse gases?

Existing Setting

Greenhouse gases (GHGs) are those gases that trap heat in the atmosphere. GHGs are emitted by natural and industrial processes, and the accumulation of GHGs in the atmosphere regulates the earth’s temperature. GHGs that are regulated by the State and/or EPA are carbon dioxide (CO2), methane (CH4), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6) and nitrous oxide (NO2). CO2 emissions are largely from fossil fuel combustion. In California, approximately 43 percent of the CO2 emissions come from cars and trucks. Electricity generation is another important source of CO2 emissions. Agriculture is a major source of both methane and NO2, with additional methane coming primarily from landfills. Most HFC emissions come from refrigerants, solvents, propellant agents and industrial processes, and persist in the atmosphere for longer periods of time and have greater effects at lower concentrations compared to CO2. The adverse impacts of global warming include impacts to air quality, water supply, ecosystem balance, sea level rise (flooding), fire hazards, and an increase in health related problems.

Assembly Bill 32 (AB 32), the California Global Warming Solutions Act, was adopted in September 2006 and requires that statewide GHG emissions be reduced to 1990 levels by the year 2020. This reduction would be accomplished through regulations to reduce emissions from stationary sources and from vehicles. The California Air Resources Board (ARB) is the State agency responsible for developing rules and regulations to cap and reduce GHG emissions. In addition, the Governor signed Senate Bill 97 in 2007 directing the California Office of Planning and Research to develop guidelines for the analysis and mitigation of the effects of greenhouse gas emissions and mandating that GHG impacts be evaluated in CEQA documents. CEQA Guidelines Amendments for GHG Emissions were adopted by OPR on December 30, 2009. The NSAQMD has also prepared a guidance document that includes mitigations for general air quality impacts that can be used to mitigate GHG emissions, Guidelines for Assessing Air Quality Impacts of Land Use Projects. Therefore, in order to satisfy CEQA requirements, projects should make a reasonable attempt to quantify, minimize and mitigate GHG emissions as feasible.

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Impact Discussion

Impact Discussion 7a-b: Would the Proposed Project generate greenhouse gas emissions, either directly or indirectly, that may have a significant impact on the environment? Would the Proposed Project conflict with any applicable plan, policy or regulation of an agency adopted for the purpose of reducing the emissions of greenhouse gases?

Given the complex interactions between various global and regional-scale physical, chemical, atmospheric, terrestrial, and aquatic systems, it is not possible to determine to what extent this project’s CO2 emissions would result in any altered physical conditions. Typically, cumulative impacts are analyzed and mitigated in the County’s General Plan and associated EIR. In this case, the General Plan for Nevada County does not address GHG emissions. Additionally, no thresholds have been adopted for project greenhouse gas emissions.

Short-term GHG emission impacts would result from construction of the site. The CalEEMOD.2013.2.2 model described in the Air Quality section of this Initial Study found that construction emission of the Proposed Project would generate approximately 655 metric tons of CO2e (CO2e is Carbon Dioxide Equivalent, a measurement that expresses units of different greenhouse gases as equivalent to units of carbon dioxide in the ability to affect global warming) (CalEEMod Version 2013.2.2 2015).

Following construction, the Proposed Project would generate greenhouse gases via generator maintenance and vehicle source CO2e emissions. In total, all operational CO2e would be approximately 4.0 metric tons per year (CalEEMod Version 2013.2.2 2015). Operational CO2 levels would therefore result in a small and incremental increase in CO2 levels with only infrequent new vehicle trips for pump station and treatment system maintenance. Other than the pump stations and ponds, no new structures would be constructed with the project.

Mitigation Measures 3B (using grid power instead of diesel generators) and 3C (prohibiting open burning) would help to reduce greenhouse gas emissions during the project’s construction phase. Additionally, the Attorney General’s document titled “Addressing Climate Change at the Project Level” includes recommendations for design, construction, and operational measures that can reduce GHG emissions of projects (California Attorney General's Office 2010). As such, staff is recommending Mitigation Measures 7A and 7B from “Addressing Climate Change” to reduce and reuse construction waste and reduce construction vehicle idling time. With the implementation of these mitigation measures, construction impacts related to CO2 emissions are anticipated to be less than significant with mitigation.

Mitigation and Residual Impact

To offset potentially adverse greenhouse gas impacts associated with proposed construction activities, the following mitigation measure shall be required:

Mitigation Measure 7A: Reduce and reuse construction waste where feasible. Prior to issuance of grading and improvement permits, the applicant shall include a note on all plans to the effect that project contractors shall “Reuse and recycle construction and demolition waste (including, but not limited to, soil, vegetation, concrete, lumber, metal, and cardboard) to the greatest extent practicable.”

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department

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Mitigation Measure 7B: Limit construction vehicle idling time. Prior to issuance of grading and improvement permits, the applicant shall include a note on all plans to the effect that “Construction equipment idling times shall be minimized either by shutting equipment off when not in use or reducing the maximum idling time to 5 minutes (as required by the California airborne toxics control measure Title 13, Section 2485 of California Code of Regulations [CCR]) and all construction equipment shall also be maintained and properly tuned in accordance with manufacturer’s specifications.” Clear signage shall be provided for construction workers at all access points.

Timing: Prior to issuance of the grading permits or improvement plans Reporting: Agency approval of permits or plans Responsible Agency: Planning Department

8. HAZARDS / HAZARDOUS MATERIALS

Less Than Potentially Less Than Significant Significant Significant No Impact Would the Proposed Project: with Impact Impact Mitigation a. Create a significant hazard to the public or the environment through the routine transport, use, or disposal of  hazardous materials? b. Create a significant hazard to the public or the environment through reasonably foreseeable upset and accident  conditions involving the release of hazardous materials into the environment? c. Emit hazardous emissions or handle hazardous or acutely hazardous materials, substances, or waste within one-quarter  mile of an existing or proposed school? d. Be located on a site which is included on a list of hazardous materials sites compiled pursuant to Government  Code Section 65962.5 and, as a result, create a significant hazard to the public or the environment? e. For a project located within an airport land use plan or, where such a plan has not been adopted, within two miles of a public airport or public use airport, would the project result in a  safety hazard for people residing or working in the project area? f. For a project within the vicinity of a private airstrip, would the project result in a safety hazard for people residing or  working in the project area? g. Impair implementation of or physically interfere with an adopted emergency response plan or emergency evacuation  plan? h. Expose people or structures to a significant risk of loss, injury or death involving wildland fires, including where  wildlands are adjacent to urbanized areas or where residences are intermixed with wildlands? i. Increase the potential exposure of the public to disease vectors and public nuisance organisms (including but not limited to mosquitoes, rodents, fleas, and ticks) that can  transmit diseases to humans and other animals, cause a significant risk of harm, injury, death, or otherwise have a substantial adverse effect on quality of life? North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 68 of 113 July 9, 2015

Less Than Potentially Less Than Significant Significant Significant No Impact Would the Proposed Project: with Impact Impact Mitigation j. Create or contribute standing water for more than 96 hours, either above or below ground, conducive to the production of mosquitoes, or other vectors defined in the California Health  and Safety Code which can include wetlands, stormwater treatment control BMPs, animal facilities, or any other shallow stagnant water feature? k. Impede or prevent vector control/public health professionals from performing duties or activities associated with protecting the public from vector-borne disease risks, or impose structural  or regulatory impediments which may inadvertently encumber control activities?

Existing Setting

The property is not within or adjacent to any hazardous materials sites compiled pursuant to Government Code Section 65962.5 (California Department of Toxic Substances Control n.d.), and is not located on an abandoned solid waste disposal site known to the County. The project area is designated as a Very High Fire Hazard Area for wildland fire (CAL FIRE 2007).

Impact Discussion

Impact Discussion 8a: Would the Proposed Project create a significant hazard to the public or the environment through the routine transport, use, or disposal of hazardous materials?

The purpose of the Proposed Project is to treat water draining from historical mine features. Treatment of the mine drainage water is by passive means, including biological treatment and pH balancing. The project does not include the use of any hazardous materials. Therefore, there would be a less than significant impact associated with the use of hazardous materials during project operation.

Impact Discussion 8b,d : Would the Proposed Project Create a significant hazard to the public or the environment through reasonably foreseeable upset and accident conditions involving the release of hazardous materials into the environment? Would the Proposed Project be located on a site which is included on a list of hazardous materials sites compiled pursuant to Government Code Section 65962.5 and, as a result, create a significant hazard to the public or the environment?

This section is based on the Phase 1 Environmental Site Assessment prepared by Worthington Miller Environmental, which also describes the results of a Preliminary Endangerment Assessment conducted for the site (Worthington Miller Environmental, LLC December 30, 2014).

Hazardous Materials Release during Construction

Small quantities of hazardous materials would be stored, used, and handled during construction. The hazardous materials anticipated for use are small volumes of petroleum hydrocarbons and their derivatives (e.g., gasoline, oils, lubricants, and solvents) required to operate the construction equipment. These relatively small quantities would be below reporting requirements for hazardous materials business plans and would not pose substantial public health and safety hazards through release of emissions or risk North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 69 of 113 July 9, 2015 of upset. Safety risks to construction workers for the Proposed Project would be reduced by compliance with Occupational Safety and Health Administration standards.

Hazardous Waste Site Status

The Grass Valley WWTP and the North Star Mine are listed as hazardous waste sites by the California Department of Toxic Substances Control (DTSC) (California Department of Toxic Substances Control n.d.). The North Star Mine is listed as a Voluntary Cleanup site with mining-caused release of arsenic in the soil, and is shown as located on the western side of Allison Ranch Road. Soil-bound arsenic to the west of Allison Ranch Road would not have an impact on the Proposed Project as the project would not release arsenic from these soils, nor would the Proposed Project have an impact on the voluntary soil cleanup of that arsenic.

The City’s WWTP property adjoins the northeast boundary of the Project Area. The WWTP has an ongoing remediation program with voluntary cleanup and has a certified monitoring program. The City entered into a Voluntary Cleanup Agreement (VCA) and Land Covenant Agreement (LCA) with DTSC in 1995 to restrict the use of the City’s WWTP property (APN 29-290-26) due to the discovery of mercury and lead-contaminated soil during expansion of the WWTP. The VCA resulted in the encapsulation of approximately 105-135 cubic yards of mercury-contaminated soil in the southwest area at the City’s property, and the LCA requires observation and measurement of the encapsulated mercury area. The City’s WWTP represents a controlled recognized environmental condition in the Project Area. As previously described, Newmont would purchase a sufficient area of APN 29-290-26 from the City necessary to collect and convey the Drew Tunnel water to the permanent treatment system, but the area to be purchased is located in the northwest portion of the City’s WWTP property, is outside the limits of the encapsulated mercury soil area, and is not known to have elevated lead or mercury concentrations in soil.

Several other sites are listed in the EDR reports on properties adjoining the Project Area or on surrounding properties (Environmental Data Resources, Inc. 2014). Based on mapped known locations, the sites are located at considerable distances or down gradient from the Project Area. As such, these sites are not considered an environmental concern to the Project Area.

The North Star Mine is currently inactive and will require voluntary cleanup, likely at such time as the property is developed for residential and/or mixed uses. Additionally, the mine drainage features addressed by the Proposed Project are leaching contaminated water into nearby water features. The Proposed Project has undergone a Preliminary Endangerment Assessment (PEA) as well as a Phase 1 Environmental Site Assessment (ESA) to evaluate the risk to the public in the mine drainage as well as the risk in remediating the drainage issue. Water quality and continuous flow monitoring has been ongoing since January 2005 for the Drew Tunnel drainage and since October 2008 for the adit and pipe culvert features. Investigations have also been performed to evaluate the physical setting, surface hydrologic features, and hydrogeologic conditions of the adit and pipe culvert and their relationship to historical mine workings. The adit and pipe culvert are associated with the historical mine workings of the Snyder Shaft and other underground workings of the North Star Mine, but are part of a larger mine drainage system for the New York Hill Mine, Chevanne Shaft, Rocky Bar and North Star underground mine workings, which are located outside of the Project Area on the North Star Property. Both features currently drain to Wolf Creek.

The PEA also addressed metal concentrations of surface water, sediment, and native soil from samples collected at locations upstream, downstream, and within the North Star Property. Several of these sampling locations were within the current boundary of the Project Area. As reported in the PEA, concentrations of mercury and methylmercury were detected in sediment samples collected from two ponds located in APN 22-160-27 and APN 22-120-28. The ponds are located along the intermittent unnamed tributary in the southern portion of the Project Area. The pond in APN 22-160-27 is located adjacent to the east side of Allison Ranch Road. The pond in APN 22-120-28 is located above the North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 70 of 113 July 9, 2015 confluence with Wolf Creek. Dissolved mercury concentrations were below detection in surface water samples collected from the unnamed tributary. While the results of the PEA indicated that the two pond areas are suitable for unrestricted land use, the PEA recommended that further evaluation of methylmercury concentrations in the pond sediments may need to be addressed prior to the previously proposed residential and commercial development of the North Star Property. The project would not disturb these ponds, so there would not be any substantial adverse impacts associated with release of mercury from these ponds.

Waste Rock

During mining operations, waste rock removed from the underground workings was commonly stockpiled adjacent to the shaft headframe. While most of the waste rock was apparently previously salvaged, a few intact waste rock piles and areas of scattered waste rock remain near the former mines within the southern portion of the Project Area. The waste rock is generally acid neutralizing with a low acid-generating potential, and the solubility of arsenic, lead, and mercury in waste rock is insoluble to low. None of the intact waste rock piles on the property are located within the proposed footprint of the passive water treatment system, and the Proposed Project would not disturb or use waste rock from the piles in the construction of the Project facilities. Minimal areas of scattered waste rock may be disturbed by the proposed Project facilities; however, this scattered waste rock is so minor that disturbance is considered to represent a de minimis condition as defined by ASTM E Practice 1527-13 (Worthington Miller Environmental, LLC, 2014).

Potential for Pond and Pipeline Leaks

As described in the Project Description of this document, the sedimentation pond would be double-lined with 60-mil high density polyethylene (HDPE) liner, with an intervening leak detection system and sump for leak extraction if it should occur. The leak detection system would consist of a geo-grid material installed between the primary and secondary liners, with instrumentation in the geo-grid layer to detect any leakage from the primary liner. Any water leakage from the primary liner would be captured by the geo-grid layer and conveyed to a sump where the water would be returned to the sedimentation pond. The sedimentation pond contains two independent ponds to provide operational flexibility and allow each pond to be drained for maintenance or repair if leakage is detected from the primary liner, while still maintaining treatment in the other pond.

The wetland pond and oxic limestone reactor beds are designed with a single 60-mil HDPE liner because the sedimentation pond would remove the majority of iron. All the ponds are designed with additional freeboard to contain a 100-year precipitation event.

The proposed pipeline is manufactured from HDPE, a generally very resilient material. The applicant would use automatic flow meters and alarms to monitor the influent into the piping system and out of the treatment system. A constant water balance would be monitored, so any breakage or spillage would quickly be identified.

Water Quality Monitoring

This project is under the purview of the Central Valley RWQCB, who would be responsible for issuing and monitoring a Limited Threat NPDES permit for the Proposed Project if the Use Permit is approved by Nevada County. The RWQCB would be responsible for reviewing the regular surface water quality monitoring reports and engaging in follow-up action as needed.

Groundwater monitoring is not anticipated because the sedimentation pond is double-lined with a leak detection system, the treated water would be cleaner than the water otherwise being discharged, and iron and manganese are not considered very mobile given the local soil conditions. Surface water monitoring North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 71 of 113 July 9, 2015 would likely occur at monthly intervals (similar to the schedule currently used at the Drew Tunnel drainage), and monitoring locations likely include the outfall location and an upstream location against which to compare the monitoring results.

Construction of the Drew Tunnel Pump Station would have the effect of remediating the contaminated drainage currently at that location and would therefore have a beneficial effect in terms of hazardous material release. Similarly, construction of the adit, pipe culvert, and spring pump stations would attenuate the contaminated water in those features. The water treatment plant would resolve the contamination by neutralizing the hazardous materials present. There would be no hazardous materials used during project operation, with the exception of propane tanks to support the emergency standby generators at the pump station. The emergency generators would be activated in the event of a power shutdown and would help to protect the watershed from further contamination from the mine drainage features. Given that the project would not release any hazardous materials into the environment but would have beneficial impacts in terms of abating the current leaching of hazardous materials into the public byways, there would be less than significant impacts.

Impact Discussion 8c: Would the Proposed Project emit hazardous emissions or handle hazardous or acutely hazardous materials, substances, or waste within one-quarter mile of an existing or proposed school?

The project area is not within one-quarter mile of an existing or proposed school. Therefore, there would be no impact related to hazardous emissions or substances near a school.

Impact Discussion 8e-f: For a project located within an airport land use plan or, where such a plan has not been adopted, within two miles of a public airport or public use airport, would the project result in a safety hazard for people residing or working in the project area? For a project within the vicinity of a private airstrip, would the project result in a safety hazard for people residing or working in the project area?

The Proposed Project is not within two miles of a public or private airport. Therefore, there would be no impact related to safety of the public within the vicinity of an airport.

Impact Discussion 8g: Would the Proposed Project impair implementation of or physically interfere with an adopted emergency response plan or emergency evacuation plan?

The Proposed Project would not alter any allowable residential density in the nearby area, or change any of the existing road networks or alter any existing emergency evacuation plans. Additionally, Nevada County Consolidated Fire District, CalFire, and City of Grass Valley Fire Department have reviewed the project proposal and did not comment on any adverse impacts to emergency response or evacuation plans. The Proposed Project would not impair or physically interfere with the adopted emergency response and evacuation plans, and any potential adverse impacts would be less than significant.

Impact Discussion 8h: Would the Proposed Project expose people or structures to a significant risk of loss, injury or death involving wildland fires, including where wildlands are adjacent to urbanized areas or where residences are intermixed with wildlands?

The Project Area is within a Very High Fire Hazard Severity Zone as mapped by CAL FIRE (CAL FIRE 2007), a zone which requires the preparation of a Fire Protection Plan per Land Use and Development Code Section L-II 4.3.18.C.4 (Nevada County 2012). Fire District approval of the Fire Protection Plan would be a condition of approval for the project because it is a Code requirement. However, the Nevada North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 72 of 113 July 9, 2015

County Fire Marshal’s Office has determined that there would be no road access issues for this project. Therefore, the project would not adversely expose unexpected volumes of people or structures to possible wildland fires, and there would be less than significant impacts.

Impact Discussion 8i,j,k: Would the Proposed Project increase the potential exposure of the public to disease vectors and public nuisance organisms (including but not limited to mosquitoes, rodents, fleas, and ticks) that can transmit diseases to humans and other animals, cause a significant risk of harm, injury, death, or otherwise have a substantial adverse effect on quality of life? Would the Proposed Project create or contribute standing water for more than 96 hours, either above or below ground, conducive to the production of mosquitoes, or other vectors defined in the California Health and Safety Code which can include wetlands, stormwater treatment control BMPs, animal facilities, or any other shallow stagnant water feature? Would the Proposed Project impede or prevent vector control/public health professionals from performing duties or activities associated with protecting the public from vector-borne disease risks, or impose structural or regulatory impediments which may inadvertently encumber control activities?

Water would continually flow throughout the treatment system at an average rate of 720 gpm, from the conveyance piping to the sedimentation pond and from there to the wetlands pond and limestone bed, and then to the Wolf Creek tributary. Therefore, the ponds would not create or contribute standing water for more than 96 hours, either above or below ground, conducive to the production of mosquitoes, or other vectors defined in the California Health and Safety Code. Given the continual flows into and out of the sedimentation and wetland ponds and the steep bank design, there is a low likelihood of the creation of mosquito breeding habitat. For comparison purposes, the Empire Mine Magenta Drain treatment ponds receive much lower flows and have not been a documented source of mosquito breeding. Nevada County’s Vector Control Division inspected the Empire Mine treatment ponds June 8, 2012 and did not find any evidence of mosquito larvae. However, with any bodies of water, particularly the wetland pond that may be heavily vegetated, thereby preventing water movement, there is a possibility of mosquito breeding. Therefore, Mitigation Measure 8A would require monthly inspections for a minimum of the first two summers of pond operation. This mitigation would result in an impact that is less than significant with mitigation.

Mitigation & Residual Impact

To offset the potential for mosquito breeding habitat in the treatment ponds, the following mitigation measure shall be required:

Mitigation Measure 8A: Routinely monitor and treat the proposed ponds for mosquito larvae. For the first two summers after construction of the treatment ponds, the applicant shall contact the Environmental Health Department’s Vector Control Division and coordinate a Vector Control inspection of the treatment ponds for mosquito larvae once a month from May through October. The Vector Control Division shall document the results of the visit. If no larvae and no potential breeding hotspots are found, no further action shall be taken beyond documentation of the visit and results. If larvae or possible breeding sites are found, Vector Control Division staff shall provide recommendations to the project applicant on engineering control methods as needed that the applicant shall implement within two weeks’ time (e.g., re-grading any shallow spots, aerating or providing movement in the water at the location of the mosquito larvae). If these methods are insufficient to prevent the breeding of mosquitoes, Vector Control shall implement alternative methods, including but not limited to installation of mosquito fish and use of Bacillus thuringiensis israelenis (BTi) or other pesticides commonly used by Vector Control. If no larvae are found after the first two summers of monitoring, no further inspections shall be required except as determined necessary by Vector Control.

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Timing: During project operation Reporting: Once per month for three months during the first two summers of operation and as needed thereafter Responsible Agency: Vector Control Division of the Environmental Health Department

9. HYDROLOGY / WATER QUALITY

Less Than Potentially Less Than Significant Significant Significant No Impact Would the Proposed Project: with Impact Impact Mitigation a. Violate any water quality standards or waste discharge  requirements? b. Substantially deplete groundwater supplies or interfere substantially with groundwater recharge such that there would be a net deficit in aquifer volume or a lowering of the local groundwater table level (e.g., the production rate of pre-  existing nearby wells would drop to a level, which would not support existing land uses or planned uses for which permits have been granted)? c. Substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a  stream or river, in a manner that would result in substantial erosion or siltation on- or off-site? d. Substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a stream or river, or substantially increase the rate or amount of  surface runoff in a manner, which would result in flooding on- or off-site? e. Create or contribute to runoff water which would exceed the capacity of existing or planned storm water drainage  systems or provide substantial additional sources of polluted runoff? f. Otherwise substantially degrade water quality?  g. Place housing within a 100-year flood hazard area as mapped on a federal Flood Hazard Boundary or Flood  Insurance Rate Map or other flood hazard delineation map? h. Place within a 100-year flood hazard area structures that  would impede or redirect flood flows? i. Expose people or structures to a significant risk of loss, injury or death involving flooding, including flooding as a  result of the failure of a levee or dam? j. Create inundation by mudflow? 

Existing Setting

The Project Area adjoins and includes part of Wolf Creek, a perennial tributary of Bear River and the Sacramento River. Several unnamed perennial and seasonal tributaries of Wolf Creek occur within the Area. Two perennial ponds also occur within the site, along with freshwater emergent wetlands and foothill riparian habitat (mostly wetland, but also including a small area of nonwetland riparian habitat). Seasonal seeps in the Project Area also support several features that are considered mixed fen wetlands. Seepage was observed in several locations in the debris flow from the area landslides, continuing throughout the summer and fall despite dry weather. Water was also observed flowing from the adit North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 74 of 113 July 9, 2015 through the summer and fall months. The project is not located within a designated flood hazard zone, and is not near open water sources.

Impact Discussion

Impact Discussion 9a: Would the Proposed Project violate any water quality standards or waste discharge requirements?

Project grading activities would require a County grading permit and a Construction Storm Water General Permit, consistent with Construction General Permit Order No. 2009-009-DWQ, issued by the State Water Resources Control Board to address storm water runoff. The permit would address clearing, grading, grubbing, and disturbances to the ground, such as stockpiling, or excavation. This permit would also require the developer to prepare and implement a Storm Water Pollution Prevention Plan (SWPPP) with the intent of keeping all products of erosion from moving off site into receiving waters. The SWPPP includes Best Management Practices (BMPs) to prevent construction pollutants from entering storm water runoff. Mitigation Measure 6G is required to ensure the project grading would conform to State Water Resources Control Board standards and in doing so would ensure the project would result in impacts that are less than significant with mitigation.

Impact Discussion 9b: Would the Proposed Project substantially deplete groundwater supplies or interfere substantially with groundwater recharge such that there would be a net deficit in aquifer volume or a lowering of the local groundwater table level (e.g., the production rate of pre-existing nearby wells would drop to a level, which would not support existing land uses or planned uses for which permits have been granted)?

The Proposed Project would not directly or indirectly result in the use of groundwater supplies as all water removed from the mine drainages would be discharged back to Wolf Creek at an upstream location. Therefore, there would be no impact related to depletion of groundwater supplies or interference with groundwater recharge.

Impact Discussion 9c-d: Would the Proposed Project substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a stream or river, in a manner that would result in substantial erosion or siltation on- or off-site? Would the Proposed Project substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a stream or river, or substantially increase the rate or amount of surface runoff in a manner, which would result in flooding on- or off-site?

The Proposed Project would collect, convey, and treat water currently draining from three legacy mining features and an adjacent spring adjacent to Allison Ranch Road. Though the project proposes to remove the water currently draining from these mine features, it would be discharged back to Wolf Creek upstream under a Limited Threat NPDES permit, with the beneficial effect of decontaminating the drainage. Periodic monitoring would be performed to assure that the effluent meets the permit limits.

As described in Impact Discussion 4b-d, the perennial portion of unnamed tributary PT-10 conducts significant perennial flows up to 2 cfs from the terminus of Allison Ranch Canal, plus much greater flows from stormwater runoff from the watershed, and has sufficient channel stability and flow capacity to receive additionally flows without substantial adversely erosion impacts. However, the discharge of treated water could result in erosion of the seasonal tributary ST-1. Mitigation Measure 4H would reduce potential erosion into the Seasonal Tributary ST-1 by evaluating the channel dimensions and gradients North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 75 of 113 July 9, 2015 and implementing outfall design recommendations as necessary. Impacts related to erosion are therefore less than significant with mitigation.

Impact Discussion 9e-f: Would the Proposed Project create or contribute to runoff water which would exceed the capacity of existing or planned storm water drainage systems or provide substantial additional sources of polluted runoff? Would the Proposed Project otherwise substantially degrade water quality?

Construction Impacts on Water Quality

The project may have short-term impacts associated with sediment and runoff during grading and construction. Material imported during this process would be kept in piles of staged soil, and/or re-graded and distributed within the Project Area. As noted above, the project development is subject to NPDES regulations since the project ground disturbance would exceed one acre. Compliance with existing regulations and implementation of BMPs would reduce potentially significant impacts associated erosion or siltation on- or offsite to levels less than significant. Mitigation Measure 6G, which requires the applicant to obtain an approved erosion and sediment control plan, would minimize the water quality impacts associated with potential erosion during construction activities.

As described in Impact Discussion 4b-d, where construction activity is proposed uphill of wetland areas, sediment from disturbed soil could enter the wetland and downstream waters. Some project facilities would be constructed within 100 feet of wetlands, riparian areas, and/or perennial water bodies. The potential for sediment generation and transport into wetlands or other waters could result in both short- term and long-term sedimentation impacts. To protect against these sedimentation and erosion impacts, Mitigation Measure 4I from the Habitat Management Plan requires temporary sediment controls prior to grading or ground disturbance.

The system is designed to be geotechnically stable through routine and non-routine operating conditions and to accommodate the peak flows from the Drew Tunnel and Snyder Shaft pumping stations of 2,000 gpm. In addition to accommodating the pumping station peak flows, the system is designed to contain and manage 100-year storm events, not allowing overtopping. With this 100-year storm design, a 2-foot freeboard capacity has been built into the design to accommodate for pond wave action and the absence of armored spillway construction. In addition, the system is designed to divert and withstand 100-year storm events from a run-on perspective via its location a topographic high point.

Operational Impacts on Water Quality

As previously discussed in the Project Description and in the Hazards section of this Initial Study, the sedimentation pond would be double-lined with an intervening leak detection system and sump for leak extraction if it should occur. The wetland pond and oxic limestone reactor beds are designed with a single liner because the sedimentation pond would remove the majority of iron. All ponds are designed with additional freeboard to contain a 100-year precipitation event. The applicant would use automatic flow meters and alarms to monitor the influent into the piping system and out of the treatment system. A constant water balance would be monitored, so any breakage or spillage would quickly be identified. It should also be noted that the treatment system itself is a water quality measure to treat the groundwater draining from the mine features pursuant to the Cleanup and Abatement Order issued by the RWQCB (Central Valley Regional Water Quality Control Board 2014). RWQCB would conduct regular surface water monitoring at monthly intervals and would continue to have regulatory responsibility for and authority over the effluent from the site. Operational impacts would therefore not be substantially adverse.

With implementation of Mitigation Measures 4I and 6G, construction water quality impact would be less than significant with mitigation. North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 76 of 113 July 9, 2015

Impact Discussion 9g-j: Would the Proposed Project place housing within a 100-year flood hazard area as mapped on a federal Flood Hazard Boundary or Flood Insurance Rate Map or other flood hazard delineation map? Would the Proposed Project place within a 100-year flood hazard area structures that would impede or redirect flood flows? Would the Proposed Project expose people or structures to a significant risk of loss, injury or death involving flooding, including flooding as a result of the failure of a levee or dam? Would the Proposed Project create inundation by mudflow?

The proposed pipelines and water treatment area are located outside of the designated 100-year floodplain and 100-foot floodplain buffer (Nevada County n.d., from FEMA Flood Insurance Rate Maps as updated). The 100-year floodplain is generally confined to narrow bands along Wolf Creek. Therefore, there would be no impact associated with placement of housing or structures or potential risk to persons within a 100-year flood hazard area as mapped on a federal Flood Hazard Boundary or Flood Insurance Rate Map or other flood hazard delineation map.

Mitigation & Residual Impacts

See Mitigation Measures 4H, 4I, and 6G.

10. LAND USE / PLANNING

Less Than Potentially Less Than Significant Significant Significant No Impact Would the Proposed Project: with Impact Impact Mitigation a. Result in structures and/or land uses incompatible with  existing land uses? b. The induction of growth or concentration of population?  c. The extension of sewer trunk lines or access roads with capacity to serve new development beyond this Proposed  Project? d. Result in the loss of open space?  e. Substantially alter the present or planned land use of an area, or conflict with a general plan designation or zoning  district? f. Conflict with any applicable land use plan, policy, or regulation of an agency with jurisdiction over the project (including, but not limited to the general plan, specific plan,  or zoning ordinance) adopted for the purpose of avoiding or mitigating an environmental effect? g. Disrupt or divide the physical arrangement of an established community, including a low-income or minority  community?

Existing Setting

Except for the portion of APN 29-290-26 that would be purchased from the City (zoned Public) and the area of APN 22-160-27 in which the construction staging would occur (Zoned RA-1.5), most of the Project Area is located within the North Star Special Development Area (SDA) and is zoned Interim Development Reserve (IDR) by Nevada County. In the northern area of the project site, nearby land uses consist of public and commercial uses, including the WWTP and the Pine Creek shopping center to the North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 77 of 113 July 9, 2015 east. Most of the southern area of the site consists of vacant land within the SDA (primarily on the western side of Allison Ranch Road, but also on most of the property adjoining Allison Ranch to the east) and rural residential uses. Single-family residential parcels in the Carriage House Subdivision are located east of Wolf Creek and to the east of the central portion of the Project Area. The undeveloped North Star property adjoins the western boundary of the central portion of the Project Area. Past uses of the North Star property include mining and timber logging. Single-family rural residential parcels are situated to the east and west of the southern portion of the Project Area. Agricultural (grazing) land on the west side of Allison Ranch Road adjoins the southwest boundary of the Project Area.

Impact Discussion

Impact Discussion 10a,e,f: Would the Proposed Project result in structures and/or land uses incompatible with existing land uses? Would the Proposed Project substantially alter the present or planned land use of an area, or conflict with a general plan designation or zoning district? Would the Proposed Project conflict with any applicable land use plan, policy, or regulation of an agency with jurisdiction over the project (including, but not limited to the general plan, specific plan, or zoning ordinance) adopted for the purpose of avoiding or mitigating an environmental effect?

Land Use Compatibility

Except for the area of APN 29-290-26 that would be purchased from the City (with City of Grass Valley “Public” zoning) and the construction staging area (zoned Residential-Agricultural [RA]-1.5), most of the Project Area is located within the North Star Special Development Area (SDA) and is zoned Interim Development Reserve (IDR) by Nevada County. The Proposed Project is considered a “quasi-public use,” which is allowed within the IDR zoning district subject to the approval of a Use Permit. The Zoning Ordinance defines Public and Quasi-Public uses as “public service uses carried out by an agency of Federal, State or local government, including special districts or other local agencies, and uses conducted by private entities under contract, agreement or franchise with a governmental agency, if the use is a service normally provided by the agency entering into a contract of agreement” (Nevada County 2012). In this case, the Proposed Project is addressing a public water quality concern through a water treatment facility similar to a public water treatment plant, albeit using “passive” methods. The project is therefore eligible for the Use Permit process.

Use Permits are designed to “provide for those land uses that may be appropriate and compatible in a zoning district, depending on the design of the individual project and the characteristics of the proposed site and surrounding area. Such uses may either raise major land use policy issues or create serious problems for adjoining properties or the surrounding area if such uses are not properly designed and located” ((Nevada County 2012, Sec. L-II 5.6.A). One of the major objectives of the Use Permit process is to provide for the compatibility of the proposed land use with adjacent properties and the surrounding area.

The pipeline corridor and pump stations would be compatible with surrounding uses and adjacent properties because these uses would not generate operational incompatibilities such as impacts to noise, air quality, or safety issues. In the northern area of the project site (where the Drew Tunnel pump station and pipeline corridor would be located), nearby uses consist of public facilities such as the Grass Valley WWTP and Glenn Jones Park, and commercial uses such as the Pine Creek shopping center. Single- family residential parcels of the Carriage House Subdivision are located east of Wolf Creek and to the east of the central portion of the Project Area in the pipeline vicinity.

The ponds, however, are located in relatively close proximity to nearby residential uses. Most of the southern area of the site is undeveloped land within the SDA or contains rural residential uses. Single- North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 78 of 113 July 9, 2015 family rural residential parcels are situated to the east and west of the southern portion of the Project Area. Potential incompatibilities arising from the project are shown in Table 5 below, along with mitigation measures that would reduce these incompatibilities to a less than significant level. Construction impacts are mitigated throughout this Initial Study and are not shown as land use incompatibilities given that they are short-term and temporary.

Table 5. Land Use Incompatibilities and Mitigation Measures Potential Incompatibility Mitigation Measure Visual incompatibility for travelers on Allison Ranch Mitigation Measure 1A: Implement the landscape plan Road, Mote Lane, Homeward Way and King Way for the sedimentation pond and construction staging area. Possible creation of mosquito breeding habitat Mitigation Measure 8A: Routinely monitor and treat the proposed ponds for mosquito larvae Noise impacts from generator maintenance Mitigation Measure 12B: Comply with Nevada County noise standards and limit operation of generators to 7:00 AM to 7:00 PM, except as needed during an electrical power outage Potential fire hazard from maintenance personnel or Fire Protection Plan (would be included as a condition of equipment during project operation approval under the Zoning Ordinance)

As shown in Table 5, all potential incompatibilities have been addressed by recommended mitigation or would be addressed by conditions of approval required by the Nevada County Zoning Ordinance.

Policy Consistency

The Project Area is located within the Sphere of Influence of the City of Grass Valley (“Near-term Development”) and is mapped within the City’s General Plan planning area for Urban Estate Density. County General Plan goals and policies encourage planning coordination within City Spheres of Influence. Pursuant to a 2004 Memorandum of Understanding, the County and the City of Grass Valley coordinate planning and project review within the City’s Sphere of Influence. While the County retains land use jurisdiction for all projects within the sphere of influence, all discretionary projects within the City Sphere are referred to the City for review and comment in order to ensure compatibility with City codes and policies. The project has been routed to the City of Grass Valley, and no comments have been received.

The Proposed Project would comply with all required setbacks as described in the Project Description, and the project is consistent with the zoning district and General Plan designations for the site, as previously discussed. All Zoning Ordinance requirements would also be addressed in recommended conditions of approval for the project, including but not limited to the requirement for a Fire Protection Plan. The Proposed Project is therefore consistent with adopted land use plans and policies of Nevada County.

Because Mitigation Measures 1A, 8A, and 12B would lessen the incompatibilities of the project with nearby residential land uses, the project would have impacts that are less than significant with mitigation.

Impact Discussion 10b-c: Would the Proposed Project result in the induction of growth or concentration of population? Would the Proposed Project result in the extension of sewer trunk lines or access roads with capacity to serve new development beyond this Proposed Project?

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The Proposed Project would not result in growth-inducing impacts because it would not construct any infrastructure or other physical development that could serve additional development. Therefore, the project would have no impact related to future development potential offsite.

Impact Discussion 10d: Would the Proposed Project result in the loss of open space?

Although the Project Area is undeveloped, it is not designated as open space, but is zoned for IDR and RA uses. Therefore, the project would have a less than significant impact on open space.

Impact Discussion 10g: Would the Proposed Project disrupt or divide the physical arrangement of an established community, including a low-income or minority community?

The Proposed Project would not disrupt or divide the physical arrangement of any established community. The project is located within a rural and somewhat undeveloped area of the County that has scattered rural residential homes, and the Project Area adjoins to Allison Ranch Road. Therefore, no impact would occur.

Mitigation & Residual Impacts

See Mitigation Measures 1A, 8A, and 12B.

11. MINERAL RESOURCES

Less Than Potentially Less Than Significant Significant Significant No Impact Would the Proposed Project: with Impact Impact Mitigation a. Result in the loss of availability of a known mineral resource that would be of value to the region and the residents  of the state? b. Result in the loss of availability of a locally important mineral resource recovery site delineated on a local general  plan, specific plan or other land use plan?

Existing Setting

The project area is mapped within a Mineral Resource Zone (MRZ) or area of known valuable mineral deposits (Nevada County n.d., from California Department of Conservation Mineral Mapping Program).

Impact Discussion

Impact Discussion 11 a-b: Would the Proposed Project result in the loss of availability of a known mineral resource that would be of value to the region and the residents of the state? Would the Proposed Project result in the loss of availability of a locally important mineral resource recovery site delineated on a local general plan, specific plan or other land use plan?

The Proposed Project is within an MRZ and was mined from the mid-1800s to the 1950s. Nevertheless, the project is a requirement of the Central Valley RWQCB, a division of the State Water Resources North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 80 of 113 July 9, 2015

Control Board, in order to mitigate the past effects of mining on the property. The project would also not preclude (nor facilitate) future mining of the site. As such, the impact to mineral resources is considered less than significant.

Mitigation & Residual Impacts

None.

12. NOISE

Less Than Potentially Less Than Significant Significant Significant No Impact Would the Proposed Project: with Impact Impact Mitigation a. Expose persons to or generate noise levels in excess of the County’s adopted standards established in the General  Plan and Land Use and Development Code? b. Expose persons to or generate excessive ground borne  vibration or ground borne noise levels (e.g., blasting)? c. Result in a substantial permanent increase in ambient noise levels in the project vicinity above levels existing  without the project? d. Result in a substantial temporary or periodic increase in ambient noise levels in the project vicinity above levels  existing without the project? e. For a project located within an airport land use plan or, where such a plan has not been adopted, within two miles of a public airport or public use airport, would the project expose  people residing or working in the project area to excessive noise levels? f. For a project within the vicinity of a private airstrip, would the project expose people residing or working in the  project area to excessive noise levels?

Existing Setting

Ambient noise in the project vicinity predominantly comes from traffic noise from Allison Ranch Road and, to a much lesser extent, from State Route 49 to the east. Sensitive noise receptors in the project area include residential uses adjoining Allison Ranch Road, Mote Lane, King Way, and Homeward Lane, as well as any other residences in close proximity to the Project Area. The General Plan and LUDC have established daytime noise levels for residential uses as follows: a maximum allowable noise level of 75 Leq between 7 a.m. and 7 p.m., 65 Leq between 7 p.m. and 10 p.m., and 60 Leq between 10 p.m. and 7 a.m.

Impact Discussion

Impact Discussion 12a & d: Would the Proposed Project expose persons to or generate noise levels in excess of the County’s adopted standards established in the General Plan and Land Use and Development Code? Would the Proposed Project result in a substantial temporary or periodic increase in ambient noise levels in the project vicinity above levels existing without the project? North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 81 of 113 July 9, 2015

The nearest residential structure is located approximately 150 feet from the proposed sedimentation pond, although the nearest residential lot line is approximately 30 feet from the pond. The residence located at 10545 Homeward Lane is located approximately 90 feet from the construction staging area. Other residential structures are located farther than 100 feet away.

Construction would result in temporary, low-level noise impacts at the nearest residences primarily associated with excavation and earthmoving equipment. Equipment and trucks used for construction would be equipped with mufflers and would utilize other noise control techniques recommended by the manufacturer (Lyle 2015). However, given that the nearest backyard to the project features is only 30 feet away, exposure of persons to noise levels in excess of the County’s adopted standards would be less than significant with mitigation as described in Mitigation Measure 12A, which limits construction work to the hours of 7 AM to 7 PM Monday through Saturday. Operational impacts are discussed in Impact Discussion 12c below.

Impact Discussion 12b: Would the Proposed Project expose persons to or generate excessive ground borne vibration or ground borne noise levels (e.g., blasting)?

The Proposed Project is not expected to result in blasting or other activities that could cause substantial vibration impacts. Therefore, there would be no impact related to groundborne vibration.

Impact Discussion 12c: Would the Proposed Project result in a substantial permanent increase in ambient noise levels in the project vicinity above levels existing without the project?

Following construction, the operational phase of the Proposed Project would generate noise from pumps at the two pump stations and stationary backup power generators at each pump station in the event of a PG&E power outage.

The Drew Tunnel pump station would be immediately adjacent to the City of Grass Valley’s WWTP. The proposed pump station would be enclosed in a pump house structure that muffles pump noise. Normal WWTP operations and vehicle traffic along Allison Ranch Road generate higher than average ambient noise levels, and noise from the Drew Tunnel pump station and routine maintenance of it would be masked by these higher ambient noise levels. Furthermore, the nearest residence to this pump station is approximately 650 feet north.

The North Star pump station design consists of a submersible pump installed in the pump well, such that the only sound source would be water flowing in above-ground piping for a short distance at the pump station prior to pipeline burial. It is anticipated that noise levels to residential receptors from the North Star pump station would therefore be within the ambient noise of the water flowing in Wolf Creek and normal vehicle traffic along Allison Ranch Road.

The most significant noise generation during project operation would be that produced by the emergency backup power generators located at each pump station in the event of a PG&E power outage. The design includes propane-powered generator units that would have mufflers and sound enclosures. The backup power generators would be routinely “exercised” by bringing the engines up to operation temperature on a regular basis. Typical generator exercising and NSAQMD permitting is for approximately 15 minutes once every two weeks. This operation would occur during daylight business hours to minimize any noise disturbance. The backup generators would also operate continuously during a PG&E electrical outage; however, electrical outages are anticipated to be infrequent and of short duration. Bi-weekly operation of the generators, however, would be required to occur during daytime hours and comply with Nevada North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 82 of 113 July 9, 2015

County noise standards as shown in Mitigation Measure 12B. With this mitigation, project operational impacts on the nearest residents are anticipated to be less than significant with mitigation.

Impact Discussion 12e, f: For a project located within an airport land use plan or, where such a plan has not been adopted, within two miles of a public airport or public use airport, would the project expose people residing or working in the project area to excessive noise levels? For a project within the vicinity of a private airstrip, would the project expose people residing or working in the project area to excessive noise levels?

The Project Area is not within an airport land use plan area, or within the vicinity of any airport. Therefore, there would be no impact associated with airport noise.

Mitigation & Residual Impact

To offset the potential for noise impacts on the nearest residence, the following mitigation measures shall be required:

Mitigation Measure 12A: Limit construction work hours to 7:00 AM to 7:00 PM. During grading and construction, work hours shall be limited from 7:00 AM to 7:00 PM, Monday - Saturday. Prior to issuance of grading and building permits, improvement plans shall reflect hours of construction.

Timing: Prior to issuance of grading and building permits Reporting: Agency approval of permits or plans Responsible Agency: Nevada County Planning Department

Mitigation Measure 12B: Comply with Nevada County noise standards and limit operation of generators to 8:00 AM to 5:00 PM, except as needed during an electrical power outage. For regular generator maintenance, generators shall be exercised from 8:00 AM to 5:00 PM, Monday - Friday. Additionally, IDR noise standards as shown in the table shall apply to the property line of the subject property. If the County amends the noise standards in the future, any new noise standards shall apply. Noise standards shall be enforced through a complaint-driven process via the Nevada County Code Enforcement Division.

Nevada County Exterior Noise Limits Zoning District Time Period Leq Lmax IDR 7 am – 7 pm 55 75 7 pm – 10 pm 50 65 10 pm – 7 am 40 55

Timing: During project operation Reporting: Agency approval of permits or plans Responsible Agency: Nevada County Planning Department

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13. POPULATION / HOUSING

Less Than Potentially Less Than Significant Significant Significant No Impact Would the Proposed Project: with Impact Impact Mitigation a. Induce substantial population growth in an area, either directly (for example, by proposing new homes and  businesses) or indirectly (for example, through extension of roads or other infrastructure)? b. Displace substantial numbers of existing housing, necessitating the construction of replacement housing  elsewhere? c. Displace substantial numbers of people, necessitating the  construction of replacement housing elsewhere?

Existing Setting

The project area is characterized by rural residential, forested, and agricultural uses. The nearest residential use is approximately 150 feet from Proposed Project features.

Impact Discussion

Impact Discussion 13a-c: Would the Proposed Project induce substantial population growth in an area, either directly (for example, by proposing new homes and businesses) or indirectly (for example, through extension of roads or other infrastructure)? Would the Proposed Project displace substantial numbers of existing housing, necessitating the construction of replacement housing elsewhere? Would the Proposed Project displace substantial numbers of people, necessitating the construction of replacement housing elsewhere?

The Proposed Project would not result in population growth or displacement of housing or people because it consists of an environmental remediation project to treat contaminated mine discharge and does not involve new structural or infrastructure development. Therefore, the Proposed Project would have no impact related to these issues.

Mitigation & Residual Impacts

None.

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14. PUBLIC SERVICES

Less Than Potentially Less Than Significant Significant Significant No Impact Would the Proposed Project: with Impact Impact Mitigation a. Result in substantial adverse physical impacts associated with the provision of or need for new or physically altered governmental facilities, the construction of which could cause significant environmental impacts, in order to maintain acceptable service ratios, response times or other performance objectives for any of the following the public services: 1. Fire protection?  2. Police protection?  3. Schools?  4. Parks?  5. Other public services or facilities? 

Existing Setting

The following public services are provided to this site:

Fire: The Nevada County Consolidated Fire District provides fire protection services to this site. Police: The Nevada County Sheriff provides law enforcement services. Water: There is no treated water onsite. Vector Control: The Nevada County Environmental Health Department provides vector control services to the unincorporated County area.

Impact Discussion

Impact Discussion 14a.1-4: Would the Proposed Project result in substantial adverse physical impacts associated with the provision of or need for new or physically altered governmental facilities, the construction of which could cause significant environmental impacts, in order to maintain acceptable service ratios, response times or other performance objectives for any of the following the public services: fire protection, police protection, schools, and parks?

The Proposed Project consists of the development of a collection, conveyance, and treatment system to remediate contaminated mine discharge. This proposed use would not result in a new need for additional schools, parks, and police protection because it would not directly or indirectly result in increased population. The Nevada County Fire Marshal’s Office has indicated that the project would not have any impacts related to fire protection (Woody 2015). Therefore, the Proposed Project would have no impact related to these issues.

Impact Discussion 14a.5: Would the Proposed Project result in substantial adverse physical impacts associated with the provision of or need for new or physically altered governmental facilities, the construction of which could cause significant environmental impacts, in order to maintain acceptable service ratios, response times or other performance objectives for any of the following the public services: Other public services or facilities?

The Proposed Project would result in the utilization of Nevada County staff resources for vector control monitoring, inspection, and maintenance activities as described in Mitigation Measure 8A. However, North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 85 of 113 July 9, 2015 these activities would consume approximately 30 minutes of staff time once a month for three months, for a span of two years at a minimum, and ongoing monitoring on an annual basis at the same rate at a maximum. These measures are within the normal parameters of staff activities, and currently Vector Control does not charge a fee for these services because the program is funded by the State. If in the future these services become financially untenable, funding could be provided by an hourly fee program. Therefore, there would be a less than significant impact on vector control services.

Mitigation & Residual Impacts

None.

15. RECREATION

Less Than Potentially Less Than Significant Significant Significant No Impact Would the Proposed Project: with Impact Impact Mitigation a. Increase the use of existing neighborhood and regional parks or other recreational facilities such that substantial  physical deterioration of the facility would occur or be accelerated? b. Include recreational facilities or require the construction or expansion of recreational facilities that might have an  adverse physical effect on the environment? c. Conflict with established recreation uses of the area,  including biking, equestrian and/or hiking trails?

Existing Setting

The Project Area is located within the Grass Valley-Nevada City Recreation Benefit Zone, but no recreational facilities occur onsite or in close proximity to the project area (Nevada County n.d.).

Impact Discussion

Impact Discussion 15a-c: Would the Proposed Project increase the use of existing neighborhood and regional parks or other recreational facilities such that substantial physical deterioration of the facility would occur or be accelerated? Would the Proposed Project include recreational facilities or require the construction or expansion of recreational facilities that might have an adverse physical effect on the environment? Would the Proposed Project conflict with established recreation uses of the area, including biking, equestrian and/or hiking trails?

As an environmental remediation project, the project would not result in development that would affect recreational uses or increase demand for recreational uses. The Proposed Project is also unrelated to the development of any trails within the BYLT easement on APNs 29-350-03 and 29-350-16 and would not preclude any future trail development within the easements. Therefore, the Proposed Project would have no impact related to these issues.

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Mitigation & Residual Impacts

None.

16. TRANSPORTATION / CIRCULATION

Less Than Potentially Less Than Significant No Significant Significant Would the Proposed Project: with Impact Impact Impact Mitigation a. Result in an increase in traffic that is substantial in relation to the existing traffic load and capacity of the street system (i.e., result in a substantial increase in either the  number of vehicle trips, the volume-to-capacity ratio on roads, or congestion at intersections)? b. Result in a need for private or public road maintenance,  or new roads? c. Result in effects on existing parking facilities, or demand  for new parking? d. Substantially increase hazards due to a design feature (e.g., a sharp curve or dangerous intersection) or incompatible  uses (e.g., farm equipment)? e. Result in a substantial impact upon existing transit systems (e.g., bus service) or alteration of present patterns of  circulation or movement of people and/or goods? f. Result in an alteration of waterborne, rail, or air traffic  patterns or levels? g. Result in an increase in traffic hazards to motor vehicles, bicyclists, or pedestrians, including short-term construction  and long-term operational traffic? h. Result in inadequate: Sight distance? Ingress/egress?  General road capacity? Emergency access (4290 Standard)? i. Result in inconsistency with adopted policies supporting the provision of transit alternatives to automobile transportation on an equitable basis with roadway  improvements , e.g. clustered development, commuter- oriented transit, bus turnouts, sidewalks, paths, and bicycle racks?

Existing Setting

The project is located on Allison Ranch Road, Allison Ranch Road Bypass, and Mote Lane, with the pipeline alignment in the shoulder of Allison Ranch Road and Allison Ranch Road Bypass, as well as on APN 29-350-16 from the adit and pipe culvert drainages to the sedimentation pond on APN 22-120-28. Allison Ranch Road is a public, County-maintained road, while the bypass and Mote Lane are private roads on lands owned by the project applicant. APNs 29-350-16 and 22-120-28 are also private lands owned by the applicant.

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Impact Discussion

Impact Discussion 16a,b,d,h: Would the Proposed Project result in an increase in traffic that is substantial in relation to the existing traffic load and capacity of the street system (i.e., result in a substantial increase in either the number of vehicle trips, the volume-to-capacity ratio on roads, or congestion at intersections)? Would the Proposed Project result in a need for private or public road maintenance, or new roads? Would the Proposed Project substantially increase hazards due to a design feature (e.g., a sharp curve or dangerous intersection) or incompatible uses (e.g., farm equipment)? Would the Proposed Project result in inadequate sight distance, ingress/egress, general road capacity, emergency access (4290 Standard)?

The project would contribute a very minor amount of traffic on an intermittent basis during the operational phase of the project, related to maintenance and repair work. The Nevada County Department of Public Works has indicated that this project would have a negligible impact on the County-maintained road system and therefore requires neither a traffic study nor mitigation fees for the project due to the extremely low traffic volumes associated with project operation. Design issues and traffic hazards have not been identified with the operational phase of project (Pack 2015). Additionally, the Nevada County Fire Marshal’s Office has not identified any road access issues and has no conditions for the project (Woody 2015).

However, the project does have the potential to cause traffic impacts during the construction phase of the project given that much of the project construction would occur within the Allison Ranch Road right-of- way. Mitigation Measure 16A would reduce this impact to a less-than-significant level by requiring a construction traffic management plan that must be reviewed and approved by the Public Works Department.

The Public Works Department also requires a surface easement, encroachment permit for work within the County right-of-way, and approval of improvement plans to meet the County standards for trench backfill. These requirements would be conditions of approval for the project (Pack 2015). Therefore, traffic and road maintenance-related impacts would be less than significant with mitigation.

Impact Discussion 16c: Would the Proposed Project result in effects on existing parking facilities, or demand for new parking?

The Proposed Project water treatment project would not be staffed full-time, but the pump stations and treatment ponds would require occasional monitoring, maintenance, and repair. As such, parking is limited to that needed for one or two maintenance trucks. This parking is not required to be striped or paved under the provisions of the Nevada County Land Use and Development Code. The project plans identify sufficient area for parking at least two work trucks at each pump station and at the pond locations. Therefore, parking-related impacts are less than significant.

Impact Discussion 16e,g,i: Would the Proposed Project result in a substantial impact upon existing transit systems (e.g., bus service) or alteration of present patterns of circulation or movement of people and/or goods? Would the Proposed Project result in an increase in traffic hazards to motor vehicles, bicyclists, or pedestrians, including short-term construction and long-term operational traffic? Would the Proposed Project result in inconsistency with adopted policies supporting the provision of transit alternatives to automobile transportation on an equitable basis with roadway improvements, e.g. clustered development, commuter-oriented transit, bus turnouts, sidewalks, paths, and bicycle racks?

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The Proposed Project would not result in the development of uses that would substantially increase traffic or that would rely on transit services. Neither project construction nor the buildout of the water treatment ponds and pumps would interfere with the service of the nearest bus line which services the Pine Creek Center. The project would not conflict with rideshare programs or other policies supporting alternative transportation, and there would be no impact related to these issues.

Impact Discussion 16f: Would the Proposed Project result in an alteration of waterborne, rail, or air traffic patterns or levels?

The Proposed Project would not impact airport operations or other travel patterns. Therefore, there would be no impact.

Mitigation & Residual Impact

To offset the potential for traffic impacts during construction, the following mitigation measures shall be required:

Mitigation Measure 16A: Implement a Traffic Control Plan during construction. Prior to the issuance of grading or improvement permits and prior to the start of construction within the Nevada County road right-of-way, the applicant shall submit to the Department of Public Works for their review and approval a complete Traffic Control Plan. The Traffic Control Plan shall include all public roadways where work is to be performed and shall indicate each stage of work, closure dates for street and section of closure (if necessary and otherwise allowed by local jurisdiction), signage, flaggers, and any other pertinent information. The Traffic Control Plan shall be reviewed and approved by the County before the contractor begins work. Specific components of the Traffic Control Plan include the following:

a. At least one lane of traffic will be kept open at all times unless prior approval is provided by the County and any affected agency. No roads will be blocked or made inaccessible, due to the contractor's work, without prior written approval of the County and affected agencies. Fire lanes will not be blocked or obstructed at any time. b. Work shall be accomplished to provide access to all side streets and properties whenever possible. If access to adjacent property cannot be provided, all property owners with restricted access shall be notified 24 hours in advance and adequate nearby parking shall be provided and maintained until direct access can be restored. The contractor shall provide for pedestrian traffic through work areas at all times. c. Traffic control, signs, and barricades shall conform to current standards. Lighted barricades shall be used when required. Special attention shall be provided to excavation and open trenching. d. Three flaggers shall be used for any one-way traffic flow situation (two working and one as standby), and shall be furnished by the contractor. The flaggers shall be properly equipped and trained. e. Where flaggers are not visible to each other, additional flaggers shall be added as required by the County, or the contractor shall use radios. f. All holes, trenches, etc., in pavement areas will be covered with 1-inch (minimum thickness) steel plates, shimmed with temporary asphalt on edges, by 5:00 p.m. or at the end of each work day. As an option to the contractor, the holes, trenches, etc., can be backfilled and all areas within pavement areas have temporary asphalt toppings. The temporary asphalt will be regularly maintained. All areas will be completely restored within 10 working days after the work has been completed at that location. g. Contractor shall display "No Parking" signs in areas of work at least 72 hours in advance. The signs shall state the day(s), date(s), and time of construction work. "No Parking" signs shall be placed in full view along the side of the road and not more than 100 feet apart. North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 89 of 113 July 9, 2015

h. Contractor shall furnish, erect, maintain, and remove all necessary construction signs and barricades for the full term of the construction activities. i. Closure of streets can occur only between 8:00 a.m. and 5:00 p.m. if allowed by the County. At least 48 hours before a street closure, the contractor must receive permission from the County and provide appropriate signage that meets their specifications. Approval to close a street is valid for one day only. j. On the day the street is closed, the contractor will notify the Police/Sheriff and Fire Protection District and provide appropriate signage that meets County specifications. k. Lane closures may be made for work periods only. At the end of each work period, all components of the traffic control system shall be removed from the traveled way, shoulder, and auxiliary lanes. l. If emergency access is required during a temporary lane closure, workers will be present and available to take appropriate steps to immediately alter operations to provide access. m. Replace all striping and pavement marking disturbed by construction to preconstruction configuration. n. Restore all existing hardscape (pavement concrete or walkways, driveways, or other surface features disturbed by the contractor's work) to the pre-construction conditions acceptable to the County. o. Prior to commencement of work, notify all affected agencies, including the appropriate Public Works Department, Police Department/Sheriff's Office, Fire Protection District, U.S. Postal Service, Disposal Services, and local ambulance/emergency response services. p. Construction activities shall be scheduled to direct traffic flow to off-peak hours as much as practicable.

Timing: Prior to issuance of grading and improvement permits for work within the County right-of-way and work that will affect traffic flow in the County right-of-way Reporting: Agency approval of permits or plans Responsible Agency: Nevada County Public Works Department

17. UTILITIES / SERVICE SYSTEMS

Less Than Potentially Less Than Significant Significant Significant No Impact Would the Proposed Project: with Impact Impact Mitigation a. Result in a need for the extension of electrical power or  natural gas? b. Require the construction of new water or wastewater treatment facilities or expansion of existing facilities, the  construction of which could cause significant environmental effects? c. Exceed wastewater treatment requirements of the  applicable Regional Water Quality Control Board? d. Have sufficient water supplies available to serve the project from existing entitlements and resources, or are new or  expanded entitlements needed? e. Require or result in the construction of new storm water drainage facilities or expansion of existing facilities, the  construction of which could cause significant environmental effects? f. Be served by a landfill or transfer station with sufficient permitted capacity to accommodate the project’s solid waste  disposal needs? North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 90 of 113 July 9, 2015

Less Than Potentially Less Than Significant Significant Significant No Impact Would the Proposed Project: with Impact Impact Mitigation g. Comply with federal, state, and local statutes and  regulations related to solid waste? h. Require a need for the extension of communication  systems?

Existing Setting

Electrical service is provided to this area by Pacific Gas & Electric and is available to the site with the proposed extension of utility lines. Natural gas is not available in this area, but the site would utilize propane as needed for the backup generators, which is available from several providers in western Nevada County. Public water and sewage treatment is not available to this property, nor is it needed. Solid waste generated during the development of the site would be processed at the McCourtney Road Transfer Site. There are a number of wireless telephone services available in southwestern Nevada County but with variable coverage depending upon the carrier. AT&T provides land line phone service to this area.

Impact Discussion

Impact Discussion 17a-e,h: Would the Proposed Project result in a need for the extension of electrical power or natural gas? Would the Proposed Project require the construction of new water or wastewater treatment facilities or expansion of existing facilities, the construction of which could cause significant environmental effects? Would the Proposed Project exceed wastewater treatment requirements of the applicable Regional Water Quality Control Board? Would the Proposed Project have sufficient water supplies available to serve the project from existing entitlements and resources, or are new or expanded entitlements needed? Would the Proposed Project require or result in the construction of new storm water drainage facilities or expansion of existing facilities, the construction of which could cause significant environmental effects? Would the Proposed Project require a need for the extension of communication systems?

The Proposed Project would not result in development that would create a need for storm drainage facilities, water supply, or wastewater treatment facilities. The project is designed to accommodate storm runoff from the site. The project would require electrical power for the pump stations, and the project applicant proposes to extend nearby overhead PG&E lines to the pump stations as needed. The applicant has also indicated that propane would be used a backup power source in the event of electrical failure. Project plans show that the applicant is proposing a PG&E easement within an existing gravel roadbed to place overhead lines for the North Star Pump Station, from on APN 22-120-8, owned by the applicant. Because utility lines would be extended along existing disturbed roadways, there would be no additional project impacts associated with infrastructure extension not already evaluated in this Initial Study. Furthermore, extension of electrical power is regulated and approved by the utility company. Therefore, the project would have a less than significant impact related to these issues.

Impact Discussion 17f,g: Would the Proposed Project be served by a landfill or transfer station with sufficient permitted capacity to accommodate the project’s solid waste disposal needs? Would the Proposed Project comply with federal, state, and local statutes and regulations related to solid waste?

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The construction phase of the project would likely produce solid waste in the form of construction materials, vegetation chippings, and industrial toxic waste like glues, paint, and petroleum products. Construction of the Proposed Project could thus result in potentially adverse landfill and solid waste disposal impacts. Impacts would be less than significant with mitigation as identified in Mitigation Measure 17A below.

Mitigation & Residual Impacts

To offset potentially adverse impacts related to construction waste, the following mitigation measure is recommended:

Mitigation Measure 17A: Appropriately dispose of vegetative and toxic waste. Neither stumps nor industrial toxic waste (petroleum and other chemical products) are accepted at the McCourtney Road transfer station and if encountered, shall be properly disposed of in compliance with existing regulations and facilities. This mitigation measure shall be included as a note on all grading and improvement plans, which shall be reviewed and approved by the Planning Department prior to permit issuance.

Timing: Prior to issuance of grading and improvement permits Reporting: Agency approval of permits and plans Responsible Agency: Nevada County Planning Department

18. MANDATORY FINDINGS OF SIGNIFICANT ENVIRONMENTAL EFFECT

Potentiall Less Than Less Than y Significant Significant No Impact Significan with Impact t Impact Mitigation a. Does the project have the potential to degrade the quality of the environment, substantially reduce the habitat of a fish or wildlife species, cause a fish or wildlife population to drop below self-sustaining levels, threaten to eliminate a plant or  animal community, reduce the number or restrict the range of a rare or endangered plant or animal, or eliminate important examples of major periods of California's history or prehistory? b. Does the project have environmental effects that are individually limited but cumulatively considerable? (“Cumulatively considerable” means that the incremental  effects of the project are considered when viewed in connection with the effects of past, current, and probable future projects.) c. Does the project have environmental effects, which will cause substantial adverse effects on human beings, either  directly or indirectly? d. Does the project require the discussion and evaluation of a range of reasonable alternatives, which could feasibly attain  the basic objectives of the project?

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Impact Discussion

Impact Discussion 18a: Does the project have the potential to degrade the quality of the environment, substantially reduce the habitat of a fish or wildlife species, cause a fish or wildlife population to drop below self-sustaining levels, threaten to eliminate a plant or animal community, reduce the number or restrict the range of a rare or endangered plant or animal, or eliminate important examples of major periods of California's history or prehistory?

Development of the Proposed Project would comply with all local, state, and federal laws governing general welfare and environmental protection. Project implementation, mostly during construction, would result in potentially adverse impacts to aesthetics, agriculture/forestry resources, air quality, biological resources, cultural resources, geology and soils, greenhouse gas emissions, hazards/hazardous materials, hydrology and water quality, land use, noise, transportation/circulation, and utilities/service systems. Each of those impacts is mitigated to levels that are less than significant levels with mitigation as outlined in each section.

Impact Discussion 18b: Does the project have environmental effects that are individually limited but cumulatively considerable? (“Cumulatively considerable” means that the incremental effects of the project are considered when viewed in connection with the effects of past, current, and probable future projects.)

The Proposed Project would result in various potential environmental impacts, but each of those can be mitigated to a less than significant level by the recommended mitigation from this document. Where the project would have no impact, it would not contribute to cumulative impacts. In addition, issues specific to site conditions, such as site geology and soils, do not have cumulative effects. The Proposed Project is not growth inducing; thus, it would not contribute to the cumulative effects of population growth. The cumulative impacts on aesthetics, air quality, biological resources, cultural resources, geology and soils, transportation/circulation, and utilities/service systems would be reduced to less than significant levels by adhering to local, regional, state, and federal impact standards and by the adherence to the project-specific mitigation measures outlined in this Initial Study. Collectively, these potentially negative impacts are not cumulatively considerable and would result in a less than significant impact.

Impact Discussion 18c: Does the project have environmental effects, which will cause substantial adverse effects on human beings, either directly or indirectly?

The Proposed Project would comply with all local, state, and federal laws governing general welfare and environmental protection. Project implementation would not substantially degrade the quality of the existing environment because the project would not result in any significant adverse and immitigable impacts to air quality, cultural resources, geology and soils, hydrology, noise, and traffic that could cause adverse effects to humans. Therefore, project impacts on human beings would be less than significant, and no additional mitigation is required.

Impact Discussion 18d: Does the project require the discussion and evaluation of a range of reasonable alternatives, which could feasibly attain the basic objectives of the project?

Although CEQA does not require the inclusion of an alternatives analysis in a Mitigated Negative Declaration because the incorporation of mitigation measures reduces all impacts to a less-than- significant level, an alternatives analysis is provided here for the purposes of disclosing background information on the selection process for the location of the Proposed Project and the rejection of alternative locations and water treatment processes. North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 93 of 113 July 9, 2015

The basic objective of the project is to remediate surface and groundwater impacts from contaminated historic mining drainages. Conceptually, this project could occur in a different location than is currently proposed and/or using a different water treatment process. These and other alternative scenarios are evaluated in the following discussion.

Different Location Alternative

Over the last 10 years, various locations have been evaluated for siting the water treatment facility. The northern portion of the property west of Allison Ranch Road is underlain by extensive underground mine workings, including mine shafts, tunnels and stopes, as well as surface features related to the former operations of the Massachusetts Hill Mine, North Star Mine, New York Hill Mine, and associated mines. This area was determined not suitable for siting the treatment facility due to surface and subsurface hazards associated with the historic underground mine features. Directly west of the proposed treatment facility location and west of Allison Ranch Road, where topography would be more conducive to construction, the area is more visible from Allison Ranch Road and neighboring residents, and less amendable to natural screening. Based on field investigation, this area is also subject to near-surface soil saturation and the presence of wetland vegetation that would preclude excavation for pond construction.

Areas more southerly and west of Allison Ranch Road have unfavorable topography in terms of limited accessibility and slope instability. Long-term operation and maintenance energy use associated with perpetual treatment at a facility located west of Allison Ranch Road would be significantly greater than the proposed location. The greater vertical elevation difference and greater distance from the mine drainages would translate to larger pumps, possibly additional pump stations, and consequently more noise, greater resource consumption (electricity), and higher energy use. The higher energy usage would reduce the long-term sustainability of the treatment system and result in greater greenhouse gas emissions and therefore greater climate impacts.

Different Water Treatment Process Alternative

Active water treatment plant operations involving chemical oxidation and green sand filtration as is currently being used at the Drew Tunnel to remove dissolved iron and manganese concentrations from the water is an alternative water treatment process to the Proposed Project. The green sand type of system requires the use of sodium hydroxide and sodium hypochlorite chemical additives to oxidize the water in order to precipitate iron, as well as the use of potassium permanganate to absorb the manganese on the green sand filtration media. The process involves routine supervision and management as well as additional electrical supply demands. These systems still require a collection and storage pond and require additional resources to produce the electricity and chemicals, as well as the fuels for chemicals transportation, all of which affect the project’s carbon footprint.

To treat arsenic with an active system, the system would require the addition of a ferric sulfide reagent circuit to the one identified above. This circuit would decrease the water’s pH to precipitate the iron contained within the ferric sulfide reagent and the iron would co-precipitate the arsenic from the water. This addition produces further requirements for chemical production, and chemical transportation. Other processes exist which could treat this water such as reverse osmosis, but this still requires greater resource consumption (electricity) and waste material generation than the Proposed Project.

Mine Shaft Fill Alternative

It should be noted that this alternative has not been proposed or assessed by Newmont as an alternative to the project. It is included here simply to provide additional information about the consequences of such an option.

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The Empire, North Star, and Massachusetts Hill mine underground workings consist of hundreds of miles of tunnels, shafts, raises, and stopes which have no access to plug or fill. Plugging the immediate mine feature openings at the Drew Tunnel, pipe culvert and lower mine adit would act to back up the water currently being discharged from these openings, resulting in uncontrolled groundwater seeps or discharges in other areas with unknown consequences.

No-Project Alternative

The No-Project Alternative would consist of continuing with the existing interim water treatment facility at the Grass Valley Wastewater Treatment Facility. However, this alternative is not acceptable in terms of Regional Water Board permitting because it would not treat the adit, culvert, and spring drainage features, and mine water discharging from these features would continue to contaminate Wolf Creek and downstream surface waters. The No-Project Alternative also conflicts with the provisions of the Agreement between the City and Newmont and unnecessarily burdens the City of Grass Valley. The interim facility cannot remain long-term because it is currently encroaching on City of Grass Valley property that is needed for its wastewater treatment facility. The interim treatment facility technology also requires hazardous chemicals (deliveries of bleach, caustic soda, and thiosulfate per week), as well as part-time staffing, all of which would be increased in scope if the adit, culvert and spring drainage flows were added to the system.

Proposed Project Alternative

Based on the results of studies and field investigations, the proposed treatment site has been determined to be the most suitable location within the property to meet the various City, County and State requirements. Primary factors considered in locating the treatment facility included the following:

. more level topography and therefore greater constructability and access, as well as avoidance of unstable slope areas within the Project Area; . avoidance of past mining operation features within the Project Area; . fewer operation and maintenance requirements and therefore lower carbon footprint over time; . minimizing potential impacts to natural resources (wetlands, riparian areas, forested areas, and cultural resources); and . the ability to provide adequate screening of the treatment site from neighboring properties.

The lower elevation of the proposed treatment location allows single pump stations at the mine features, results in less electrical demand, less resource consumption, and fewer greenhouse gas emissions, and requires less hydraulic energy dissipation at Wolf Creek.

The proposed location is adjacent to and in close proximity to the existing mine drainage features where the water must be collected for treatment, and is also near, and upgradient from Wolf Creek, where the treated water would be discharged via gravity flow. The site is outside of the floodplain and avoids existing wetlands, historical mine features, and geologic hazards, which exist elsewhere on the property. The location is adjacent to existing electrical power supply and existing access roads, which minimizes the disturbance necessary to construct the project. The proposed treatment pond location allows conveyance piping from the mine features to be installed along existing roads, which reduces the overall area of disturbance. There are no sites within the remainder of the property which meet or exceed these conditions. For these reasons, the Proposed Project is considered the environmentally superior alternative, and alternatives would not feasibly attain the basic objective of the project in as effective a manner. Therefore, this impact is considered less than significant.

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Mitigation & Residual Impacts

See Mitigation Measures 1A, 3A-3D, 4A-4J, 5A, 6A-6G, 7A-7B, 8A, 12A-12B, 16A, and 17A. North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 96 of 113 July 9, 2015

RECOMMENDATION OF THE PROJECT PLANNER

On the basis of this initial evaluation:

I find that the Proposed Project COULD NOT have a significant effect on the environment, and a NEGATIVE DECLARATION will be prepared.

X I find that although the Proposed Project could have a significant effect on the environment, there will not be a significant effect in this case because revisions in the project have been made by or agreed to by the project proponent. A MITIGATED NEGATIVE DECLARATION will be prepared.

I find that the Proposed Project MAY have a significant effect on the environment, and an ENVIRONMENTAL IMPACT REPORT is required.

I find that the Proposed Project MAY have a "potentially significant impact" or a "potentially significant unless mitigated" impact on the environment, but at least one effect 1) has been adequately analyzed in an earlier document pursuant to applicable legal standards, and 2) has been addressed by mitigation measures based on the earlier analysis as described on attached sheets. An ENVIRONMENTAL IMPACT REPORT is required, but it must analyze only the effects that remain to be addressed.

I find that although the Proposed Project could have a significant effect on the environment, because all potentially significant effects (a) have been analyzed adequately in an earlier EIR or NEGATIVE DECLARATION pursuant to applicable standards, and (b) have been avoided or mitigated pursuant to that earlier EIR or NEGATIVE DECLARATION, including revisions or mitigation measures that are imposed upon the Proposed Project, nothing further is required.

______Jessica Hankins, Project Planner Date North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 97 of 113 July 9, 2015

REFERENCES

Bureau of Land Management. "Passive Treatment Systems for Acid Mine Drainage: Technical Note 409." April 2003. CAL FIRE. Nevada County Fire Hazard Severity Zone Map. November 2007. calfire.ca.gov/fire_prevention/fhsz_maps_nevada.php (accessed July 7, 2015). —. "Notice of Intent to Harvest Timber." May 14, 2015. CalEEMod Version 2013.2.2. "North Star Water Treatment Ponds." July 1, 2015. California Attorney General's Office. "Addressing Climate Change at the Project Level." January 6, 2010. California Department of Conservation. California Important Farmland Finder. n.d. maps.conservation.ca.gov/ciff/ciff.html# (accessed July 7, 2015). California Department of Conservation, Division of Mines & Geology. "Report 2000-19: A General Location Guide for Ultramafic Rocks in California -- Areas More Likely to Contain Naturally Occurring Asbestos." 2000. California Department of Toxic Substances Control. Envirostor Database. n.d. www.envirostor.dtsc.ca.gov (accessed June 26, 2015). California Department of Transportation. California Scenic Highway Mapping System. n.d. www.dot.ca.gov/hq/LandArch/scenic_highways/ (accessed July 7, 2015). Central Valley Regional Water Quality Control Board. "Cleanup and Abatement Order R5-2014-0706 for Newmont USA, Ltd: North Star Property, Nevada County." August 15, 2014. City of Grass Valley. City of Grass Valley Zoning Map. January 2011. www.cityofgrassvalley.com/files/attachments/maps/zoning_c.pdf (accessed July 7, 2015). Ecosynthesis Scientific & Regulatory Services. "North Star Water Treatment Facility: Biological Inventory Report." 2014. Ecosynthesis Scientific and Regulatory Services, Inc. "North Star Mine Water Treatment Project Biological Questions." June 18, 2015. Environmental Data Resources, Inc. "North Star DT and North Star PTS: The EDR Radius Map Report with Geocheck." Database Report, 2014. Ernst, Donna, Senior Project Environmental Scientist, Golder & Associates. Email to Jessica Hankins, Nevada County Planning Department. June 23, 2015. Haire, Bill, Trails Coordinator, Bear Yuba Land Trust. "Email to Jessica Hankins, Nevada County Planning Department." June 11, 2015. Hankins, Jessica, Nevada County Planning Department. "Site visits to Empire Mine Water Treatment Facility." Grass Valley, June 5 and 12, 2015. Huggins, Jeff, Water Resources Control Engineer, Title 27 Permitting and Mining Unit, Central Valley Water Board. "Email to Jessica Hankins, Nevada County Planning Department." May 27, 2015. Jensen, Sean Michael. "Class I Archaeological Survey: North Star Mine Water Treatment Project." August 20, 2013. —. "Class III Archaeological Survey: North Star Mine Water Treatment Project." February 27, 2015. Lowe, Lance, Senior Planner, City of Grass Valley. "Email to Jessica Hankins, Nevada County Planning Department." June 29, 2015. Lyle, William, Director, Closure/Reclamation, Newmont Mining Corp. Email to Jessica Hankins, Nevada County Planning Department. June 3, 2015. North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 98 of 113 July 9, 2015

MWH. "Geologic Hazards Evaluation for the Proposed North Star Water Conveyance and Treatment Area." 2014, 2. Nevada County. Nevada County General Plan. 1995 with revisions through October 2014. —. Zoning and Parcel Information: My Neighborhood Interactive Map. n.d. www.mynevadacounty.com/nc/cda/planning/Pages/Zoning-and-Parcel-Information.aspx (accessed July 7, 2015). —. Zoning Regulations. 2012. Northern Sierra Air Quality Management District. "Guidelines for Assessing and Mitigating Air Quality Impacts of Land Use Projects." 2009. Pack, Joshua, Principal Civil Engineer, Nevada County Department of Public Works. "Memo to Tod Herman re North Star Water Treatment Project." January 28, 2015. Tencate. Geosynthetics: Geotube Dewatering Technology. n.d. www.tencate.com/amer/geosynthetics/solutions/dewatering_technology/ (accessed June 30, 2015). US Environmental Protection Agency. Current Nonattainment Counties for All Criteria Pollutants. January 31, 2015. www.epa.gov/oaqps001/greenbk/ancl.html (accessed July 7, 2015). USDA Soil Conservation Service. "Soil Survey of Nevada County Area, California." Soil Survey, Reissued 1993. Woody, Jon, Fire Protection Planner/Deputy Fire Marshal. "Letter to Tod Herman re U14-009." January 21, 2015. Worthington Miller Environmental, LLC. "Phase 1 Environmental Site Assessment." December 30, 2014. Worthington, Sherm, interview by Nevada County Planning Department Jessica Hankins. (June 30, 2015). —. "Email to Jessica Hankins, Nevada County Planning Department: 'North Star Passive Water Treatment Project - Landscape Plan'." June 24, 2015.

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FIGURES

Figure 1: Project Location Map North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 100 of 113 July 9, 2015

Figure 2: Site Plan North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 101 of 113 July 9, 2015

Figure 3: Northern Project Area North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 102 of 113 July 9, 2015

Figure 4: Southern Project Area North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 103 of 113 July 9, 2015

Figure 5: Drew Tunnel Pump Station North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 104 of 113 July 9, 2015

Figure 6: North Star Pump Station North Star Water Treatment Facility – U14-009, MGT14-015, EIS14-012 105 of 113 July 9, 2015

Figure 7: Pipe Trench and Road Details

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Figure 8: Biological Inventory Habitat Map

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Figure 9: Geologic Features

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Figure 10: Geologic Hazards Overview Map

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Figure 11: Northernmost Geologic Hazards

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Figure 12: North Central Geologic Hazards

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Figure 13: Central Geologic Hazards

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Figure 14: South Central Geologic Hazards

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Figure 15: Southernmost Geologic Hazards