Wetland Habitat Mitigation and Monitoring Plan
Lodi Gas Storage, L.L.C. Kirby Hills Natural Gas Storage Facility, Solano County (U.S. Army Corps of Engineers File Number 2007-400516N) Prepared for: U.S. Army Corps of Engineers, San Francisco District; San Francisco Bay Regional Water Quality Control Board; and San Francisco Bay Conservation and Development Commission
Project Applicant and Responsible Party:
Lodi Gas Storage, L.L.C. P.O. Box 230 23265 N. State Route 99 Acampo, CA 95220 Contact: Scott Wilson Telephone: (209) 368-9277 ext. 11 Facsimile: (209)368-9276 Email: [email protected] With Technical Assistance from:
ICF Jones & Stokes 630 K Street, Suite 400 Sacramento, CA 95814 Contact: Sue Bushnell 916/752-0959
May 2008
ICF Jones & Stokes. 2008. Wetland habitat mitigation and monitoring plan. May. (ICF J&S 05746.05.) Sacramento, CA. Prepared for: U.S. Army Corps of Engineers, San Francisco District; San Francisco Bay Regional Water Quality Control Board; and San Francisco Bay Conservation and Development Commission.
Contents
Chapter 1 Project Description and Proposed Mitigation ...... 1-1 Responsible Party...... 1-1 Purpose of This Habitat Mitigation and Monitoring Plan ...... 1-1 Project Location ...... 1-2 Project Summary ...... 1-2 Summary of Effects on Waters of the United States ...... 1-4 Mitigation Site ...... 1-4 Mitigation Design ...... 1-9 Basis of Design ...... 1-9 Characteristics of Design Reference Site ...... 1-10 Created and Restored Habitats ...... 1-10 Compensation Ratios ...... 1-10 Long-Term Goals ...... 1-11 Aquatic Functions ...... 1-11 Hydrology ...... 1-11 Topography ...... 1-12 Soils and Substrate ...... 1-12 Vegetation ...... 1-12
Chapter 2 Success Criteria and Monitoring ...... 2-1 Success Criteria...... 2-1 Hydrology ...... 2-2 Vegetation Cover ...... 2-2 Monitoring ...... 2-3 Methods ...... 2-3 Monitoring Schedule ...... 2-4 Photo-Documentation ...... 2-4 Annual Reports ...... 2-4
Chapter 3 Implementation Plan ...... 3-1 Site Preparation ...... 3-1 Preconstruction Phase ...... 3-2 Grading Implementation ...... 3-2 Avoidance Measures ...... 3-3 Soil Treatment ...... 3-3 Pest Plant Removal ...... 3-3 Construction Monitoring ...... 3-4 Planting and Seeding...... 3-5 Planting Plan ...... 3-5 Planting Methods ...... 3-5
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Nature and Source of Propagules ...... 3-6 Irrigation ...... 3-7 Implementation Schedule ...... 3-7 As-Built Drawings ...... 3-8
Chapter 4 Maintenance during the Monitoring Period ...... 4-1 Maintenance Activities ...... 4-1 Expected Maintenance Activities ...... 4-1 Irrigation ...... 4-2 Weed Management ...... 4-2 Replacement Planting ...... 4-3 General Site Maintenance and Repairs ...... 4-3 Maintenance Inspections ...... 4-4 Proposed Monitoring Reports ...... 4-4 As-Maintained Drawings ...... 4-4 Annual Reports ...... 4-4 Potential Contingency Measures ...... 4-4
Chapter 5 Completion of Mitigation ...... 5-1 Notification of Completion ...... 5-1 Confirmation of Completion ...... 5-1
Chapter 6 Contingency Measures ...... 6-1 Initiating Procedures ...... 6-1 Alternative Locations for Contingency Mitigation ...... 6-1 Funding Mechanism for Contingency Mitigation ...... 6-1
Chapter 7 Long-Term Management ...... 7-1 Property Ownership ...... 7-1 Management Plan...... 7-1 Management Approach ...... 7-1 Site Protection ...... 7-2
Chapter 8 References Cited ...... 8-1
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Tables
On Page
1 Waters of the United States Delineated in the Wetland Delineation Study Area ...... 1-6
Figures
Follows Page
1 Project Vicinity ...... 1-2
2 Kirby Hills I and Kirby Hills Phase II Project Area Boundaries ...... 1-2
3 Project Site Plan for Phase II Project Components ...... 1-3
4 Proposed Wetland Restoration Site and Permanent and Temporary Fill Areas ...... 1-3
5 Project Site Profile for Temporary and Permanent Work Over Area for Well W5 ...... 1-3
6 Proposed Wetland Reference Sites ...... 1-7
7 Conceptual Wetland Mitigation Plan, Cross Section ...... 1-13
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Chapter 1 Project Description and Proposed Mitigation
Responsible Party
The project applicant with financial responsibility for attaining the success criteria described in this Wetland Habitat Mitigation and Monitoring Plan (HMMP) is:
Lodi Gas Storage, L.L.C. P.O. Box 230 23265 N. State Route 99 Acampo, CA 95220
Contact: Scott Wilson Telephone: (209) 368-9277 ext. 11 Facsimile: (209) 368-9276 Email: [email protected] Purpose of This Habitat Mitigation and Monitoring Plan
This HMMP describes the on-site compensatory mitigation proposed by Lodi Gas Storage, L.L.C. (LGS) to compensate for impacts on 0.40 acre of waters of the United States (WUS) (including 0.30 acre of permanent and 0.10 acre of temporary impacts) resulting from the rehabilitation of an existing well (Wagenet 5 [Well W5]) in the Suisun Marsh Primary Management Area. This HMMP is intended to support the acquisition of permits from the U.S. Army Corps of Engineers (USACE), San Francisco Bay Regional Water Quality Control Board (RWQCB), and San Francisco Bay Conservation and Development Commission (BCDC). The HMMP is consistent with mitigation and monitoring proposal guidelines issued by the Sacramento and San Francisco Districts of the USACE (U.S. Army Corps of Engineers 2004).
The HMMP proposes the following.
Restoration of approximately 0.90 acre of disturbed mud flat to brackish marsh habitat. Brackish marsh is a naturally occurring habitat in adjacent
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areas and probably historically existed at the restoration site. This restoration is intended to offset permanent loss of 0.30 acre of disturbed brackish marsh, which will result in a compensation ratio of 3 to 1 impact acres to compensation acres. The restoration site will be restored through a combination of the following measures:
removal of fill material (previously deposited on top of a natural wetland area located adjacent to Well W5),
regrading the site to match adjacent natural site contours and elevations (thereby restoring natural hydrologic functioning), and
both active and passive revegetation to create a self-sustaining brackish marsh.
Restoration of 0.10 acre of disturbed brackish marsh located along the toe slope of the existing access road and Well W5 well pad. This site will be temporarily impacted during well rehabilitation and pad restoration and will be restored back to brackish marsh following work on the well. Site restoration includes regrading and recontouring the disturbed site and actively revegetating the site with brackish marsh plant species.
Project Location
The Kirby Hills Natural Gas Storage Facility is located in a rural agricultural area in the Montezuma Hills and Kirby Hills of southeastern Solano County and is within the Suisun Basin (see Figure 1).
The existing facility is approximately 6 miles west of Rio Vista and 8 miles southeast of Fairfield. The facility extends between the Kirby Hills and Birds Landing Road (Figure 2). The additional facilities that are being constructed as part of the proposed Phase II project occur within the Secondary Marsh and Primary Marsh Management Areas and drain into Nurse Slough, which is a tributary to Montezuma Slough.
The proposed fill activity and associated restoration site occurs in the Suisun Marsh Primary Management Area, immediately north of the Kirby Hills. It is located on the Denverton quadrangle, latitude/longitude: 38.169595 North and 121.912553 West, in an unsectionalized area of T4N, R1E and T4N, R1E, S30.
Project Summary
The purpose of the expansion project is to provide added storage capacity at the Kirby Hills facility and a stable supply of natural gas for LGS customers. The Phase II components are needed because pipeline capacity into California has more than tripled in the last 15 years and demand has risen as well—mostly because of population growth and electric power plants switching from oil to natural gas to fuel their boilers and reduce air pollutant emissions.
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Auburn 29 Lincoln 80 175 16 113 49 Rocklin YOLO 5 99 Roseville
Folsom
128 29 Woodland 50
Calistoga NAPA 505 Davis West Sacramento Mather AFB 101 Winters
128 128 116 Santa Rosa 16 80 Dixon 12 Elk Grove 113 5 SACRAMENTO Vacaville Rohnert Park 29 121 Napa SOLANO 99 Sonoma Project Location Fair eld 160 88 Petaluma 80 Suisun 12 116 City 12 Rio Vista Isleton 101 37 Vallejo 680 Lodi 1 Novato 12 Benicia 160 88 26 MARIN West Pittsburg 4 Bethel Is. Pittsburg Stockton Martinez Antioch Richmond Concord Mill Valley 24 Walnut Creek 4 5 SAN Berkeley CONTRA JOAQUIN Danville COSTA Manteca Tracy 680 San Ramon SAN FRANCISCO San Leandro 580 99 Modesto Hayward Livermore Paci ca 580 132 92 1 ALAMEDA Fremont San Mateo 33
Redwood City Patterson Palo Alto Milpitas
0 10 20 SAN 35 SANTA CLARA 280 Newman Miles MATEO Cupertino Saratoga Gustine Los Gatos 35 101 5 1 Morgan Hill Project 17 Location 152 Gilroy Santa Cruz 152 Capitola Watsonville 25 1 129 Hollister 156 05246.05 (2-08) Figure 1 Project Vicinity 12 113
12 Shiloh Rd.
Phase II Project Components: Phase II Project Component: • Injection/Withdrawal Wells • PG&E Interconnection • Flow Line • Compression/Dehydration • Conversion of Abandoned Wells Olsen Rd.
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LEGEND 0 0.5 1.0 Miles
Kirby Hills I Project Area Boundary 0 0.5 1.0 1.5 Kilometers
USGS Quadrangles: 7.5-minute series Plase II Project Area Boundary Bird’s Landing, Antioch North, Denverton, and Honker Bay, California quadrangles 05246.05 (2-08) Figure 2 Kirby Hills I and Kirby Hills Phase II Project Area Boundaries Lodi Gas Storage, L.L.C Chapter 1. Project Description and Proposed Mitigation
The proposed Phase II project is comprised of the following five primary components.
Three new well pad sites containing up to 15 injection and withdrawal wells (Wells 21, 22, and 23).
A 12-inch-diameter, approximately 2,700-foot pipeline (flow line) connecting the wells to the existing compressor station.
A new compressor enclosure and additional dehydration equipment at the existing compressor station site.
An expanded Pacific Gas and Electric (PG&E) interconnection at the existing metering station.
Rehabilitation of three existing wells (Wells Lambie 6, Lambie 7, and Well W5).
Figure 3 provides a general overview of these major project components (with the exception of the meter station and PG&E interconnection located immediately west of Birds Landing Road, which is located in the Central Valley RWQCB and will not impact waters of the State or WUS).
Of these project components, only the rehabilitation of Well W5 and associated restoration of the well pad and access road will result in the placement of fill material into WUS. The remaining project components have been designed to avoid sensitive environmental resources and will not directly impact any WUS. Figure 4 shows the work area associated with Well W5 and the anticipated impacts to WUS. Figure 5 shows the cross section for the fill material that will be used to restore the access road to and pad around Well W5. This project component is described in detail below.
Well W5 is located on the site of an old drilling pad in the Suisun Marsh Primary Management Area. The well drilling pad was constructed in 1947, as evidenced by historic photographs (Jones & Stokes 2007), and was used to drill Well W2, which is next to Well W5. Well W5 was drilled from the drilling pad as a directional well in late 1985. Subsequently, Dow Chemical partially restored a portion of the Well W5 well pad and access road, but a large portion of the area still contains fill material. The fill material was determined by ICF Jones & Stokes to consist of up to 31 inches of soft sandstone and clay topsoil that was obtained from a borrow site in the nearby Kirby Hills (Jones & Stokes 2007).
The reuse of the Well W5 site as a natural gas storage facility will necessitate the restoration of the original access road and the restoration of the well pad around Well W5. The primary work on the surface will involve restoration of the degraded well pad and access road to Well W5. Subsurface work at the well will include drilling out cement plugs, logging the well, placing a casing in the open hole section, and perforating. All work would be done from the site of the original well pad that was used to construct Wells W2 and W5.
Habitat Mitigation and Monitoring Plan May 2008 Kirby Hills Natural Gas Storage Facility, Phase II 1-3 05725.05
Acreage of Permanent Acreage of Impact Temporary Impact Restoration Restoration Access Road 0.13 -- Well Pad 0.17 0.10 LIMITS OF PREVIOUSLY CONSTRUCTED Proposed Wetland Mitigation Site 0.90 0.10 WELL ACCESS PAD/MUD FLAT BOUNDARY (PROPOSED RESTORATION AREA) TOTAL 0.30 0.10 0.90 0.10 (includes 0.25 acre brackish (includes 0.01 acre brackish
Proposed mitigation ratio is 3:1 for permanent impact (0.30 acre) and 1:1 for temporary impact (0.10 acre) on Waters of the U.S.
TEMPORARY FILL AREA AROUND WELL PAD
WELL PAD
RESTORATION OF ACCESS ROAD
BRACKISH MARSH BOUNDARY
Proposed Wetland Restoration Site
Figure 4 Restoration and Rehabilitation Plan for Temporary and Permanent Work Over Area for Well 5 05246.05 15 - Kirby Hills Phase II Wetland Mitigation Plan (rev. 05-08) 05246.05 15 - Kirby Hills Phase Figure 4 Proposed Wetland Restoration Site and Permanent and Temporary Fill Areas
Lodi Gas Storage, L.L.C Chapter 1. Project Description and Proposed Mitigation
Summary of Effects on Waters of the United States
A total of 9.191 acres of jurisdictional wetland habitats (i.e., brackish marsh and seasonal wetlands) and 1.041 acres of other WUS (i.e., mud flats and two seasonal drainages) occurs in the wetland delineation study area (Jones & Stokes 2007). The project is expected to result in permanent loss of 0.30 acre and temporary disturbance of an additional 0.10 acre of other WUS habitats resulting from rehabilitation of Well W5 and the associated restoration of the well pad and access road.
Permanent and temporary impacts on jurisdictional WUS habitats are described in more detail below.
Permanent
The proposed project will result in permanent loss of 0.30 acre of WUS (including 0.25 acre of disturbed brackish marsh and 0.05 acre of mud flat/fill material). Rehabilitation of Well W5 and restoration of the well pad site will result in permanent impacts to 0.17 acre of habitat, and restoration of the original access road leading to Well W5 will affect 0.13 acre of previously disturbed habitat.
Temporary
Rehabilitation of Well W5 will temporarily impact 0.10 acre of disturbed brackish marsh habitat along the perimeter of the well pad. This area will be restored and revegetated following project construction.
Mitigation Site
LGS plans to restore and enhance 0.90 acre of mud flats (confirmed to be previously deposited fill material) located just north of Well W5 to offset the permanent loss of 0.30 acre of WUS habitats. This restoration activity would be conducted within an area that was previously disturbed during installation of Wells W5 and W2 (see Figure 4). At present, the proposed wetland mitigation site is covered with up to 31 inches of fill material, consisting of soft sandstone and clay topsoil from a borrow pit in the Kirby Hills that was deposited at the site in the 1940s. The disturbed mud flat will be restored to brackish marsh by removing the fill material, and restoring the natural site hydrology by excavating down to restore natural site contours. Temporary construction impacts on the 0.10 acre of disturbed brackish marsh around the Well W5 site will be restored in its original location following well rehabilitation activities.
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Location
The proposed wetland mitigation site is located at the existing Well W5 site (Figures 3 and 4).
Present and Historical Uses of the Mitigation Area
The proposed wetland mitigation site is located in the Suisun Marsh Primary Management Area. The general region is designated as the Kirby Hills Gas Field by the California Division of Oil, Gas and Geothermal Resources. Natural gas exploration and development have occurred in the field since the 1930s. Well W5 is located on private land that is owned by Christopher and Lisa Wohn. Currently, the area contains natural gas facilities (Wells W2 and W5) and is grazed by livestock.
Present and Proposed Uses of All Adjacent Areas
The wetland mitigation site is adjacent to the Kirby Hills. Nearby land uses include dry land farming (principally wheat), duck hunting, and livestock grazing. The project area is within the western portion of the Collinsville– Montezuma Hills Wind Resource Area, designated by Solano County in 1987 as land suitable for wind energy development.
Jurisdictional Areas
A wetland delineation was prepared by Jones & Stokes in May 2007 (Jones & Stokes 2007) and was verified by the USACE in February 2008 (Department of the Army, San Francisco Regulatory District, U.S. Army Corps of Engineers File Number 2007-400516N). The wetland delineation encompassed the greater 72.4-acre project area for the proposed expansion of gas storage facilities in the Kirby Hills that contained potential WUS (Jones & Stokes 2007).
WUS were delineated in order to determine the location and extent of areas that would be regulated by the USACE under Section 404 of the Clean Water Act. The waters were delineated in accordance with the 1987 Corps of Engineers Wetlands Delineation Manual (1987 Manual) (Environmental Laboratory 1987) and the recently released supplement to the 1987 Manual that provides specific guidance for the Arid West Region, the Interim Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Arid West Region (U.S. Army Corps of Engineers 2006), where this supplement replaces sections of the 1987 Manual.
In summary, the delineation area encompasses 9.191 acres of jurisdictional wetlands (i.e., brackish marsh and seasonal wetlands) and 1.041 acres of other WUS (i.e., mud flats and two seasonal drainages). Table 1 summarizes the
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jurisdictional wetlands and other WUS identified in the wetland delineation study area and the potential jurisdictional status of each (Jones & Stokes 2007).
Table 1. Waters of the United States Delineated in the Wetland Delineation Study Area
Wetland Feature Wetland / Waters Jurisdictional Status Acreage in Type Study Area BM-1 Brackish marsh Wetlands 8.081 BM -2 Brackish marsh Wetlands 0.037 W-1 Seasonal wetland Wetlands 0.455 W-2 Seasonal wetland Wetlands 0.473 W-3 Seasonal wetland Wetlands 0.135 W-4 Seasonal wetland Wetlands 0.010 Total Wetlands 9.191 MF-1 Mud flat Other waters of the United States 1.016 D-1 Seasonal drainage Other waters of the United States 0.006 D-2 Seasonal drainage Other waters of the United States 0.019 Total Other Waters of the United 1.041 States Total Waters of the United States 10.232
Of these jurisdictional habitats, 0.40 acre of WUS is anticipated to be affected by the project, including:
0.25 acre of previously disturbed brackish marsh that will be permanently impacted;
0.05 acre of previously disturbed mud flats (previously deposited fill material) that will be permanently impacted; and
0.10 acre of previously disturbed brackish marsh that will be temporarily affected.
Aquatic Functions
As described above, the WUS that would be affected by the project consist of 0.40 acre of previously disturbed brackish marsh and mud flat habitats. These habitats provide the following aquatic functions.
Floodwater retention/detention. Because of their small size and non- depressional topography, the habitats provide for a very small amount of floodwater retention/detention when the marsh is flooded to manage duck
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habitat. However, when the greater marsh is closed to tidal water entry by a levee, the habitats detain incident rainfall.
Nutrient retention/degradation. Because of their small size, the habitats provide for a very small amount of nutrient degradation, with the brackish marsh habitat providing more water quality improvement benefits compared to the mud flat habitat.
Wildlife habitat. The habitats provide a relatively small amount of foraging habitat for shorebirds. The brackish marsh habitat provides some cover for waterfowl, but this is limited by the sparse vegetation cover.
Hydrology
The project area is located in the Suisun Bay hydrologic unit, U.S. Geological Survey Cataloging Unit 18050001 (U.S. Environmental Protection Agency 2007). The climate in the project area is characterized by warm, dry summers, and cool, rainy winters. The mean annual precipitation is approximately 12–20 inches; the mean annual air temperature is approximately 58ºF; and the average frost-free period is approximately 260 days. (Jones & Stokes 2007)
The jurisdictional areas that will be affected by the rehabilitation of Well W5 are located at the base of the Kirby Hills and extend into the adjacent mud flat and managed (diked) brackish marsh area adjacent to Nurse Slough. No named surface water bodies exist within the impact area proper.
The jurisdictional areas that will be affected appear to be supported by incident precipitation and by seasonal inundation as a result of tide gates being opened to manage the marsh for duck habitat. The brackish marsh that will be affected probably is also supported by prolonged high groundwater. Saturation in the root zone and/or ponding is expected to occur for 30 consecutive days or more.
Topography
The topography of the areas to be affected by the project is nearly level to very gently sloping; elevations range between approximately 1.6 to 5.2 feet above mean sea level (msl) (Figure 6).
Soils and Substrate
The USDA Soil Conservation Service Soil Survey of Solano County, California (Bates 1977) shows that the area where jurisdictional areas will be affected consists of Joice muck (map unit Ja). Joice muck consists of nearly level, very deep, very poorly drained, moderately rapidly permeable, very strongly acid, strongly saline, high mineral content organic soils found in level saltwater marshes. According to the soil survey, because Joice soils are managed, the
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Acreage of Permanent Acreage of Impact Temporary Impact Restoration Restoration Access Road 0.13 -- Well Pad 0.17 0.10 Proposed Wetland Mitigation Site 0.90 0.10 TOTAL 0.30 0.10 0.90 0.10 (includes 0.25 acre brackish (includes 0.01 acre brackish
Proposed mitigation ratio is 3:1 for permanent impact (0.30 acre) and 1:1 for temporary impact (0.10 acre) on Waters of the U.S.
LIMITS OF PREVIOUSLY CONSTRUCTED WELL ACCESS PAD (PROPOSED RESTORATION AREA)
TEMPORARY FILL AREA AROUND WELL PAD
PERMANENT WELL PAD
NOT TO SCALE
Proposed Wetland Mitigation Site Reference Sites/ Grade Control Points Transect 05246.05 15 - Kirby Hills Phase II Wetland Mitigation Plan (rev 05-08) Figure 6 Proposed Wetland Reference Sites Lodi Gas Storage, L.L.C Chapter 1. Project Description and Proposed Mitigation
water table is typically deeper than 30 inches in midsummer but near the surface in the winter. Based on ICF Jones & Stokes’ field observations, thin layers of fill material have been placed in some parts of the jurisdictional areas to be affected.
Vegetation
Existing vegetation in the wetland restoration project area includes brackish marsh and mud flats, which are described in more detail below.
Brackish marsh supports a mixture of plants tolerant of saline and brackish water conditions, such as salt marsh bulrush (Scirpus robustus), pickleweed (Salicornia virginica), hardstem bulrush (Scirpus acutus), Baltic rush (Juncus balticus), Mexican rush (Juncus mexicanus), annual saltbush (Atriplex triangularis), common purslane (Portulaca oleracea), brassbuttons (Cotula coronopifolia), and alkali heath (Frankenia grandifolia).
These species tend to grow according to elevation levels, with hardstem bulrush occurring along the lowest lying areas, such as the edges of ditches (referred to in this HMMP as “low marsh”); salt marsh bulrush and pickleweed in intermediate topographic positions(referred to in this report as “intermediate elevation brackish marsh”); and a mosaic of brass buttons, alkali heath, pickleweed, purslane, Baltic and Mexican rush, and annual saltbush at the higher topographic positions, in transitional areas adjacent to annual grassland vegetation (referred to in this HMMP as “high marsh”).
Mud flats located in the vicinity of the mitigation site are mostly unvegetated and occur where fill was placed on top of the native brackish marsh vegetation. The mud flats are typically unvegetated or sparsely vegetated high marsh with a mixture of brass buttons, alkali heath, pickleweed, and purslane comprising about 30% cover or less (depending on the season). Mud flats exhibit signs of periodic inundation such as salt crust and wrack lines.
Vegetation surrounding the wetland restoration site is intermediate elevation brackish marsh, comprised of an almost monotypic stand of salt marsh bulrush, with occasional pickleweed. Overall vegetative cover is approximately 70–90%. It is considered likely that the mud flat fill area was originally vegetated with mostly intermediate elevation brackish marsh species (mainly salt marsh bulrush), based on the observed elevation of the underlying native soil and the condition of the surrounding vegetation at similar elevations on all sides of the fill area.
Threatened and Endangered Species
Based on the technical surveys and analyses conducted to support the project design (including avoidance of sensitive resources) and the California Public Utilities Commission’s (CPUC’s) California Environmental Quality Act
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document (a subsequent initial study/mitigated negative declaration [Subsequent IS/MND]), ICF Jones & Stokes determined that the mitigation area does not support federally listed endangered or threatened species.
Mitigation Design Basis of Design
The existing Well W5 and the adjacent wetland restoration site were heavily disturbed in the past during construction of the original wells (Figure 4). As a result of construction of the original Wells W2 and W5 and access roads (1940s), a layer of fill was placed just north of the Well W5 pad site. The fill encompasses approximately 0.90 acre, and based on observations of the surrounding vegetation types, was likely to have historically supported intermediate elevation brackish marsh vegetation.
The fill material that currently occupies the site consists of up to 31 inches of clay topsoil and fragments of weathered, soft sandstone that is situated on top of the native soil (Joice muck). Based on ICF Jones & Stokes’ observations, the fill material matches the materials observed at a nearby borrow pit in the Kirby Hills. Because this material is less permeable than the surrounding native organic soil and is elevated approximately 12 to 18 inches above the natural ground surface, the fill material prevents inundation and groundwater movement from the supporting wetland vegetation into the fill area. As a result, the fill area is largely unvegetated mud flat habitat.
The proposed wetland mitigation is intended to restore the selected mitigation site back to approximately preproject conditions (i.e., pre- 1940s well construction). Restoration will include:
removal of fill material (previously deposited on top of the natural wetland area located adjacent to Well W5);
regrading the site to match adjacent natural site contours and elevations (thereby restoring natural hydrologic function); and
active and passive revegetation to create a self sustaining intermediate level brackish marsh.
The proposed restoration is anticipated to result in the following benefits.
Improvements in function and interconnectivity of native habitats on site.
Increased and improved hydrologic and water quality functions (through restoration of natural grades.
Increased vegetation and wildlife habitat services resulting from the conversion of disturbed mud flat vegetation to more typical intermediate level brackish marsh species that favor saturated or inundated conditions.
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Characteristics of Design Reference Site
Six reference sites were identified north, south, east, and west of the mitigation site within the adjacent undisturbed brackish marsh (Figure 6). These reference sites were selected to establish the grade across the fill area and for monitoring comparison purposes.
At present, all of the selected design reference sites (as well as all areas immediately adjacent to the wetland mitigation site) support intermediate elevation brackish marsh, which comprises an almost monotypic stand of salt marsh bulrush (approximately 65–70% cover) with occasional pickleweed (approximately 2–5% cover).
Created and Restored Habitats
An approximately 0.90-acre wetland mitigation site will be used for the restoration of brackish marsh habitat. Restoration of this site will include the following.
Removing the fill material from the approximately 0.90-acre wetland mitigation site. Fill material will be used to restore the well pad site around Well W5 and restore the access road to the well pad.
Grading the wetland mitigation site down to approximate natural site contours using adjacent reference points to establish the natural grade across the site and to restore the natural site hydrology, based on excavated depth to native soil material and matching the contours and elevation of the adjacent undisturbed habitats.
Reestablishing brackish marsh vegetation through both active and passive restoration techniques. Active restoration will include initial plug-planting of brackish marsh vegetation from adjacent undisturbed brackish marsh vegetation areas. Passive restoration will include allowing native vegetation to recolonize the site from adjacent natural areas over time.
Compensation Ratios
The permanent loss of 0.30 acre of previously disturbed brackish marsh and mud flats will be offset by the restoration of approximately 0.90 acre of brackish marsh, resulting in a 3:1 compensation ratio. This ratio takes into consideration the temporal loss of wetland habitat.
Temporary disturbance of 0.10 acre of the previously disturbed brackish marsh will be compensated through restoration of 0.10 acre of temporarily disturbed brackish marsh, resulting in a 1:1 compensation ratio.
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Long-Term Goals
The long-term goals for the wetland mitigation site are listed below.
Offset permanent project impacts on of 0.30 acre of brackish marsh and mud flats and 0.10 acre of temporary impacts on brackish marsh habitat.
Reestablish the historic context of the 0.90-acre site by connecting brackish marsh habitat at the mitigation site with similar adjacent habitats to create a large vegetated wetland mosaic.
Establish self-sustaining brackish marsh habitat.
Improve hydrologic site functions, wildlife habitat values, and habitat values to wetland plant species.
Reuse excavated fill material (approximately 2,338 cubic yards) to restore the access road and well pad (an estimated 2,343 cubic yards of material is needed).
Aquatic Functions
After the mitigation has been implemented and the vegetation established, the mitigation site is expected to provide the following aquatic functions.
Floodwater retention/detention. Because the topography will be level, the mitigation site will provide for a small amount of floodwater retention/detention when the marsh is flooded to manage duck habitat and during periods of rainfall.
Nutrient retention/degradation. The increased soil permeability and greater vegetation cover will promote nutrient retention and degradation.
Wildlife habitat. Compared to the existing condition, the mitigation site will provide less foraging habitat for shorebirds but greater cover and nesting habitat for other wildlife. Restoration of the site will also improve the connectivity of the adjoining brackish marsh.
Hydrology
Once the mitigation site has been restored to its prefill elevation, it is expected that incident rainfall and managed floodwaters during the winter will saturate and inundate the surface soil within the restoration site in a manner similar to surrounding undisturbed areas. The duration of saturation/inundation is expected to occur for at least 30 consecutive days.
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Lodi Gas Storage, L.L.C Chapter 1. Project Description and Proposed Mitigation
Topography
Following the wetland restoration, site topography will be returned to near natural grade. Using reference points located in undisturbed marsh areas adjacent to the mitigation site, the elevation of the restoration site will be lowered by up to approximately 31 inches (i.e., the maximum depth of the fill material) and will be carefully established to match the elevation of the reference points. The final elevation will range from a low of 0.68 foot msl at the northeastern corner of the mitigation site to a high of 0.90 foot msl at the southwestern corner of the site and be approximately flat at 0.81 foot msl from the western edge to 0.86 foot msl to the eastern edge. The result will be a site that is slightly sloping upward from the northeast to the southwest. Soils and Substrate
The proposed wetland restoration work will return the mitigation site to its original grade, removing most of the nonnative fill material and exposing the native soil (Joice muck) in places. Because the final grade is the determining factor in successful vegetation establishment in this habitat type, exact elevations must be matched across the site. As a result, small pockets of fill may be left behind and will be lightly mixed with the underlying native soil to help ensure that the site soils are permeable and will support brackish marsh vegetation. This action will improve the hydraulic conductivity of the site, thereby promoting lateral groundwater movement from the perimeter to the interior of the site.
Vegetation
A combination of active and passive restoration is proposed for the project. The proposed mitigation site will be regraded, and then active restoration implemented immediately.
During the active restoration phase, the site will be planted with 4- to 6-inch plugs of marsh plants collected from the surrounding areas. Vegetation surrounding the site is intermediate-elevation brackish marsh, comprised of an almost monotypic stand of salt marsh bulrush, with occasional pickleweed. It is probable that the mud flat fill area was originally vegetated with mostly salt marsh bulrush, based on the observed elevation of the native soils and the condition of the surrounding vegetation on all sides of the fill area.
Plant collection will therefore emphasize intermediate elevation marsh, which is dominated by salt marsh bulrush, with occasional pickleweed. Soil-plant plugs (approximately 4 to 6 inches in diameter) will be collected manually (e.g., use of a shovel) or mechanically (e.g., use of small mechanical equipment such as a bobcat) and then planted at the restoration site. The plugs will be installed at an approximate spacing of 3 feet on-center to facilitate rapid establishment and cover.
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Refer to Figure 7 for a cross-sectional schematic of the revegetation plan.
Passive restoration will follow the active restoration phase. As the restoration site is periodically inundated with flood waters from the surrounding low marsh areas and goes through a natural wetting and drying cycle, seeds from a variety of brackish marsh species will be deposited in the newly established restoration site. Over time, it is assumed other brackish marsh species will establish within the restoration site.
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Wetland Mitigation
existing vegetation (sparse) elevation reference elevation reference point = 0.81 feet existing grade of fill point = 0.86 feet
existing brackish marsh native soil existing brackish marsh
4 - 6” clusters of plug plantings spaced 3 feet on-center approximate grade of mitigation wetland
not to scale 05246.05 Wetland Mit Plan (4-08) 05246.05 Wetland Mit Plan Figure 7 Conceptual Wetland Mitigation Plan, Cross Section Chapter 2 Success Criteria and Monitoring
This section describes the monitoring plan for the restored wetlands at the proposed wetland mitigation site, including success criteria, monitoring schedule, monitoring methods, remedial measures, and reporting/documentation requirements.
LGS or its designated representative (a qualified restoration ecologist) will manage the monitoring and reporting. Vegetation will be monitored for a 5-year period after the initial wetland restoration actions are completed. However, if the success criteria are met before this monitoring period ends, no additional monitoring is recommended.
Success Criteria
For this HMMP, success criterion indicates whether the mitigation goals have been achieved at the end of the performance monitoring period.
The success criteria for brackish marsh plant survival have been developed to ensure that the restored habitat matches the vegetation species composition and vegetative cover observed at the reference sites located in the adjacent natural habitats of the same type. The success criteria for vegetative cover are based on the anticipated cover values resulting from a combination of active planting of brackish marsh species and from natural colonization of seeds from the surrounding areas. Baseline data will be collected at the wetland mitigation site and at designated reference sites prior to site disturbance (Figure 6).
Baseline data will also be used to compare pre- and postconstruction species composition and relative cover values, as stated in the USACE 50/20 Rule (refer to discussion below).
If the wetland restoration site does not achieve the success criteria by Year 5, LGS will consult with the resource agencies on appropriate monitoring or remedial measures achieve the project’s mitigation goals.
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Hydrology
The restored wetland will be considered to have met the hydrology success criteria if inundation or saturation within 12 inches of the surface is present for 30 consecutive days or more during the growing season.
Vegetation Cover
The success criteria for vegetative cover are described below for each year.
Year 1: Vegetation cover of typical brackish marsh species within the revegetation site will be at least 50% of the vegetation cover of typical brackish marsh species observed in the same year at the six adjacent reference sites (note: within-year comparisons are intended to correct for seasonal vegetation variations). Vegetation cover of upland species within the restoration site will be less than 20% of the total vegetation cover present, and invasive plant cover will not exceed 2%.
Year 2: Vegetation cover of typical brackish marsh species within the revegetation site will be at least 70% of the vegetation cover of typical brackish marsh species observed in the same year at the six adjacent reference sites (note: within-year comparisons are intended to correct for seasonal vegetation variations). Vegetation cover of upland species will be less than 15% of the total vegetation cover present, and invasive plant cover will not exceed 1%.
Year 3: The vegetation cover of typical brackish marsh species within the revegetation site will be at least 80% of the vegetation cover of typical brackish marsh species observed in the same year at the reference site (note: within-year comparisons are intended to correct for seasonal vegetation variations). Vegetation cover of upland species within the restoration site will be less than 10% of the total vegetation cover present, and invasive plant cover will not exceed 1%.
Year 4: The vegetation cover of typical brackish marsh species within the revegetation site will be at least 85% of the vegetation cover of typical brackish marsh species observed in the same year at the reference site (note: within-year comparisons are intended to correct for seasonal vegetation variations). Vegetation cover of upland species within the restoration site will be less than 5% of the total vegetation cover present, and invasive plants will not be present.
Year 5: The vegetation cover of typical brackish marsh species within the revegetation site will be at least 90% of the vegetation cover of typical brackish marsh species observed in the same year at the reference site (note: within-year comparisons are intended to correct for seasonal vegetation variations). Vegetation cover of upland species within the restoration site will be less than 2% of the total vegetation cover present, and invasive plants will not be present.
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Monitoring Methods
Monitoring of the restored brackish marsh will include assessing hydrologic conditions, vegetative cover, and plant species composition, as described below.
Hydrology
The mitigation site will be visited at regular intervals during the period that the overall marsh is flooded for duck habitat management. The number and frequency of site visits will be such that the presence of the wetland hydrology success criterion can be documented. The depth to groundwater or the depth of surface water (inundation) will be observed and recorded in at least four mitigation site locations. Such observations will also be made in the adjoining marsh to serve as points for comparison. Once the hydrology success criterion has been met throughout the mitigation site for a given monitoring season, the hydrology monitoring may be suspended, but it is recommended that this monitoring continue to document the hydrologic period in both the mitigation site and the reference wetland area.
Vegetation
Vegetation will be monitored annually for 5 years (or less if the success criterion has been met before the 5-year monitoring visit). The timing of the vegetation surveys may vary slightly each year, depending on when the peak plant identification period occurs, but will most likely occur in May.
Vegetation monitoring will include observing and recording the following site conditions at both permanent quadrat locations within the restoration site and the reference brackish marsh sites (Figure 6).
Absolute cover of vegetation will be monitored within sampling quadrats at both the reference sites and the restoration site. Sampling will be collected within 1 meter square sampling quadrats. A minimum of two quadrats will be established at each of the six reference sites, and at least 12 random sampling quadrats will be established within the restoration site each year of monitoring. Data collected in each of the sampling quadrats will then be averaged for the revegetation site and the reference sites, respectively, and then compared.
Plant species composition (i.e., percent absolute cover of dominant and subdominant plant species observed within each quadrat) and overall plant species richness (i.e., total number of species present in all sampling quadrats) will also be recorded in each quadrat. Results should indicate number and absolute cover of brackish marsh plants, other wetland plants,
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upland plants, and also note any nonnative invasive plants that may require treatment. Sampling methods are described in more detail below.
Acres of brackish marsh habitat present (defined as areas supporting more than 50% absolute cover of typical brackish marsh species) will be used to assess areas meeting the USACE 50/20 rule as a measure of the amount of potential jurisdictional wetlands present on site. The 50/20 Rule is used to determine the dominant species in a given vegetative stratum in each wetland and to determine whether the wetland is dominated by wetland plant species. According to the 50/20 Rule, the dominant plant species are those that, when ranked in descending order of abundance and then added in descending order, immediately exceed 50% of the total abundance measure. In addition, any species that individually makes up 20% or more of the total abundance measure for the stratum is also a dominant species. The dominant species in that stratum within a given wetland are then used to determine the presence of hydrophytic vegetation.
Monitoring Schedule
Monitoring will occur annually during the month of May. All field data will be recorded on data sheets.
Photo-Documentation
Permanent photo-documentation sites will be identified for the restoration site and reference sites during mitigation construction to provide a visual record of progress. To facilitate relocation of the permanent photo-documentation sites, sites will be selected and mapped on a base map during the first monitoring activity and a GPS position, compass bearing, and/or permanent stake will be installed. Photographs will be taken during the May vegetation monitoring visits to document vegetative conditions.
Annual Reports
LGS will prepare an annual monitoring report and submit it to USACE, BCDC, and San Francisco Bay RWQCB by December 30 of each monitoring year. Each monitoring report will include the following:
The USACE File Number 2007-400516N, on the cover and title page of all reports and correspondence;
a summary of the project location and description;
a summary of the monitoring methods;
a list of the names, titles, and affiliations of the people who prepared the content of the annual report or participated in monitoring activities that year;
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a copy of the USACE permit and any subsequent letters of modification, in an appendix;
a summary and analysis of the monitoring results, including an evaluation of site conditions in the context of the reference sites;
a discussion of the monitoring results;
management recommendations, including discussion of areas with inadequate performance and recommendations for remedial measures;
a discussion of modifications made to the monitoring methods;
a discussion of the previous year’s maintenance efforts; and
photo-documentation of the restored wetland using photographs taken from the permanent photo-documentation locations.
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Chapter 3 Implementation Plan
This chapter describes the implementation plan for restoring wetlands within the proposed wetland mitigation site. Specifically, this chapter discusses the site preparation methods, grading methods, planting methods, construction inspections, and requirements for as-built drawings.
Site Preparation
Site preparation at the approximate 0.90-acre wetland restoration site will include setting up multiple reference sites in the existing brackish marsh and using an automatic level to determine the final grade, site contours, slope, and topography to allow the restored site to function hydrologically with the surrounding area. Figures 6 and 7 show the location and relationship of the wetland restoration site to the reference sites. The objective is to create a similar, but slightly sloping grade across the site that allows water (both surface and groundwater) to flow evenly across the undisturbed brackish marsh and restoration site.
Final grade and elevation are critically important to establishment of brackish marsh vegetation. As little as 2 inches lower, or as much as 6 inches higher, than the elevation of the surrounding existing brackish marsh could shift the vegetation composition in the restored site dramatically. For example, if the grade is too low, soils will be close to groundwater levels and will pond with surface water for a longer duration than surrounding areas, resulting in a reduced vegetation plant cover (inability of target plants to establish). In contrast, a grade that is too high will result in a slightly drier soil surface and a related shift to high marsh vegetation (described above). Therefore, multiple reference sites and triangulation between reference sites will be used to determine the final grade of the restoration site to help ensure establishment of intermediate elevation marsh (Figure 6).
LGS will survey and stake control points in and adjacent to the wetland restoration site. This action will be performed by a professional surveyor with the assistance of a restoration specialist.
Site preparation at the 0.10 acre temporary disturbance site will include re- contouring the site to original grade, removing any remaining temporary erosion control structures that were required during construction, and raking the underlying soils to prepare them for planting.
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Preconstruction Phase
Site preparation during the preconstruction phase will include identifying the following actions:
staking the work area;
staking the boundaries of adjacent existing brackish marsh to be avoided;
collecting exact spot elevations at reference sites (Figure 3) and using spot elevations to determine final grade for the restoration site;
installing lath- and flagging along the wetland restoration site boundary; and
preparing the temporary impact site by removing any remaining temporary erosion control structures around the Well W5 site and raking soils to prepare them for planting.
Staking and Flagging the Wetland Restoration Site Boundaries
LGS will install staking (wooden lath and flagging) around the perimeter of the wetland restoration site boundary and designated access roads prior to construction. Staking and flagging are intended to provide the equipment operator with a visual barrier to help ensure the operator avoids the surrounding undisturbed brackish marsh habitat.
Soil Excavation, Stockpiling, and Disposal
As described previously, approximately 2,338 cubic yards will be excavated from the mud flat area. All of this excavated fill material will be used to restore the Well W5 pad and access road to the pad.
The fill material will be excavated from the mud flats immediately prior to work on Well W5. The material will be excavated with a backhoe and stockpiled on rubber mats in an upland area adjacent to the wetland mitigation site. The temporary soil stockpile area will be determined through coordination with LGS, the landowner (Wohns), and a biologist familiar with the resources in the project area. The fill material will be temporarily placed (expected to be less than 1 month) in an upland area near the mitigation site that does not currently contain any sensitive biological resources. No material will be stockpiled in wetlands.
Grading Implementation
As previously described, final grade and elevation are critical for the establishment of brackish marsh vegetation. Because soil in the work area will become rather wet approaching finish grade, small, light, low PSI tracked
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vehicle/grading equipment such as a bobcat is recommended. Larger grading equipment such as a small bulldozer (D3) or front-end loader may be appropriate for initial grading to “hog-out” the deeper areas of fill material. Excavation should proceed in such a way that the fill is drawn away from the perimeter of the wetland restoration site and towards the designated fill site; no equipment will be positioned in the undisturbed, existing marsh.
The excavation depth will be guided by the elevation of the established reference points in adjacent brackish marsh habitat, using triangulation to help ensure a level to gently sloping grade is established across the site, thus allowing a smooth transition across the site to the reference sites in the existing marsh (Figures 6 and 7). The objective is to create a similar, but slightly sloping grade across the site that allows water (both surface and groundwater) to flow evenly across the undisturbed brackish marsh and restoration site.
Following rough grading, the perimeter of the restoration site will be “feathered” into the surrounding marsh to ensure blending of the restoration site with the surrounding brackish marsh.
In most areas, excavation to achieve the desired grade will result in the removal of existing fill material from the site. However, in some small areas, some of the fill material will remain to ensure that undesirable low spots in the restoration site are avoided. In these areas, the equipment operator will “mix” the fill and native soils using a blade or rake.
Avoidance Measures
Avoidance measures will include preconstruction surveys and installation of lath and flagging to demarcate the perimeter of the wetland restoration site as described under Site Preparation.
Soil Treatment
No soil treatment measures are proposed as part of this HMMP.
Pest Plant Removal
With the exception of a small cluster of common reed (Phragmites australis), the wetland restoration site is largely devoid of invasive nonnative vegetation. To prevent inadvertent spread of common reed during site grading, the restoration site will be reassessed for common reed prior to site grading and any common reed plants treated with herbicide prior to site grading. Where present, the cut stems of common reed plants will be spot-treated (i.e., “painted”) with Rodeo, a water solution of the isopropylamine salt of glyphosate commonly used for reed control. Herbicides will be approved by the project manager or restoration
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ecologist, and herbicide application performed by a licensed pesticide applicator. Chemical control application will meet all federal and state laws and federal, state, and local health and water quality regulations, as well as labeling instructions.
Construction Monitoring
Progress inspections and other interim inspections of the mitigation creation and restoration operations will be conducted by LGS or its authorized representative to ensure that the mitigation site is fully and properly installed to meet performance standards. Areas not meeting the implementation standards identified in this HMMP or the construction documents will be reevaluated and replanted by LGS or its authorized representative.
LGS or its authorized representative will inspect mitigation construction and planting operations at the following critical phases of the implementation:
layout of project boundaries and features prior to construction;
collection of baseline vegetation data at reference sites and at randomly selected sampling sites within the restoration site;
installation of lath and flagging to demarcate the boundaries of the restoration site;
layout of reference points and collection of elevational data at the reference points;
rough excavation of fill from the restoration site and disposal of fill at designated areas of the Well W5 pad site and the original access road;
fine excavation and contouring of the wetland restoration site;
planting area layout;
identification and establishment of permanent photo-documentation sites for the restoration wetland and reference sites;
installation of plant plugs; and
removal of lath and flagging from around the restoration site.
Although the revegetation contractor is expected to be experienced in mitigation installation, the construction inspections described above will ensure that the intent and critical details of the mitigation design are understood and executed by the contractor.
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Planting and Seeding Planting Plan
The planting plan includes restoration of 0.90 acre of a single habitat type (brackish marsh) at the wetland restoration site. The 0.10-acre temporary impact area around the well pad will also be replanted with brackish marsh (high marsh plants) at the same time.
Plugs, approximately 4 to 6 inches wide by 4 to 6 inches long and 0.5 to 1 foot deep, will be harvested from the adjacent undisturbed brackish marsh habitat. Collections should preferably be done in the wet season, and the collected material immediately transplanted to the wetland restoration site and the temporary impact site. If immediate transportation is not possible, collected material can alternately be cared for (potted or stored, irrigated, etc.) until the sites are ready for planting. Plant collection activities will be will be scattered such that no more than 5% of the vegetation in any single area is harvested to help ensure rapid recovery of the collection sites through natural regeneration.
For the wetland restoration site, plant collection activities will emphasize collection of intermediate elevation brackish marsh species (i.e., salt marsh bulrush and pickleweed, although occasional plants of the following species may also be collected and installed at the restoration site: hardstem bulrush, Baltic rush, Mexican rush, annual saltbush, common purslane, brassbuttons, and alkali heath).
For the temporary impact site, plant collection activities will emphasize collection of high marsh species (i.e., salt marsh bulrush and pickleweed, Baltic rush, Mexican rush, annual saltbush, common purslane, brassbuttons, and alkali heath).
A total of 4,840 plugs will be harvested and installed at the 0.90-acre wetland restoration site (approximate planting spacing of 3 feet on center), and an additional 484 plants will be collected and installed at the 0.10-acre temporary impact area around the well pad.
Planting Methods
The following sections summarize the sequence for installing plant material.
Plug Plant Installation
Planting activities associated with plug plant material installation will include the following:
layout of individual plug planting locations,
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excavation of planting holes, and
installation of plant material.
Herbaceous plug plants will not require fertilizer, mychorrhizae inoculant, browse guards, watering basins, or mulch.
Plant spacing will average 3 feet on center, but plants will be laid out in a natural pattern (i.e., not in straight rows or in an evenly spaced configuration) such that the finished planting pattern mimics natural plant spacing. Pin flags may be used to check randomness of plant spacing; the pin flags will be removed after plant installation.
Planting holes should be at least 1.5 feet deep and 1 foot wide to receive the 4- to 6 -inch wide by 1-foot-deep planting plugs. Excavated soils from the planting holes should be stockpiled adjacent to the planting site then replaced around the planting plug.
Plants should be installed in the center of the planting hole, with the roots loosened and placed in a fan at the bottom of the hole. Soil should be replaced and lightly compacted (i.e., “tamped down”) around the roots as the hole is filled to help ensure proper soil-root contact.
The resulting soil surface should be even with the surrounding ground surface and lightly compacted.
Nature and Source of Propagules
A total of 5,324 planting plugs will be harvested from the intermediate elevation brackish marsh surrounding the wetland restoration site. Plant collection activities will emphasize collection of intermediate elevation brackish marsh species (i.e., salt marsh bulrush and pickleweed, although occasional plants of the following species may also be collected and installed at the restoration site and the temporary impact site: Baltic rush, Mexican rush, annual saltbush, common purslane, brassbuttons, and alkali heath).
A total of 4,840 plugs will be harvested and installed at the 0.90-acre wetland restoration site (approximate planting spacing of 3 feet on center), and an additional 484 plants will be collected and installed at the 0.10-acre temporary impact site, as described above. Plant collection activities will be scattered such that no more than 5% of the vegetation in any single area is harvested to help ensure rapid recovery of the collection sites through natural regeneration.
Plugs, approximately 4 to 6 inches wide by 4 to 6 inches long and about 0.5 to 1 foot deep, will be harvested from the adjacent undisturbed brackish marsh habitat. Collections should preferably be done in the wet season, and the collected material immediately transplanted to the wetland restoration site and the temporary impact site. If immediate transportation is not possible, collected
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material can alternately be cared for (potted or stored, irrigated, etc.) until the sites are ready for planting.
Irrigation
The need to irrigate the newly-installed plantings is not anticipated because the finished grade of the restoration site will be sufficiently close to groundwater to ensure successful plant establishment without supplemental water. However, if during monitoring, the plug plantings are found to be exceeding mortality rates specified in this HMMP, LGS will provide a water truck to irrigate the restoration site approximately once a week during dry periods.
Implementation Schedule
Rehabilitation work associated with Well W5 is planned for fall 2008. Based on this expected start date and pending the receipt of permits, LGS will implement the following schedule.
Fall 2008: Install lath and flagging to demarcate the boundaries of the restoration site, the temporary impact site, and the designated fill sites and identify and treat populations of the invasive plant common reed within the restoration site.
Fall 2008: Identify reference sites (Figure 6) and collect elevation data at the reference sites. Establish permanent photo-documentation stations on site.
Fall 2008: Collect baseline photo-documentation and vegetation monitoring data prior to soil excavation. Rough grade the wetland restoration site using elevation data at reference sites. Transport and dispose of excavated fill materials immediately at designated spoils or reuse areas. Remove any remaining erosion control structures at the temporary impact site, and prepare (rake) the soils at the temporary impact site.
Fall 2008–Winter 2009: Complete finish grading of the wetland restoration site. Lay out plant spacing with pin flags. Excavate planting holes at both the wetland restoration site and the temporary impact site. Harvest 5,324 plug plantings and immediately install at the restoration site (4,840 plants) and at the temporary impact site (484 plants). Refill planting holes and compact soils to help ensure good root-soil contact. Ensure soil surface around planting sites is level with surrounding area.
June 2009: Begin maintenance and monitoring phase of the HMMP.
December 2009: Prepare and submit 2009 Annual Monitoring Report in December 2009.
2010: Conduct hydrological monitoring during wet season, and assess need for supplemental watering. Implement any necessary remedial actions (recommended in 2009 Annual Monitoring Report) in April 2010. Conduct
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vegetation monitoring and photo documentation in May 2010. Prepare and submit Year 2 annual monitoring report in December 2010.
2011: Conduct hydrological monitoring during wet season, assess need for supplemental watering. Implement any necessary remedial actions (recommended in 2010 Annual Monitoring Report) in April 2011. Conduct vegetation monitoring and photo documentation in May 2011. Prepare and submit Year 3 annual monitoring report in December 2011.
2012: Conduct hydrological monitoring during wet season, assess need for supplemental watering. Implement any necessary remedial actions (recommended in 2011 Annual Monitoring Report) in April 2012. Conduct vegetation monitoring and photo documentation in May 2012. Prepare and submit Year 4 annual monitoring report in December 2012.
2013: Conduct hydrological monitoring during wet season, assess need for supplemental watering. Implement any necessary remedial actions (recommended in 2012 Annual Monitoring Report) in April 2013. Conduct vegetation monitoring and photo documentation in May 2013. Prepare and submit final Year 5 monitoring report in December 2013.
January 2014: Submit completion notifications to regulatory agencies; obtain agency sign-off on project.
As-Built Drawings
LGS will submit as-built drawings of the restoration site to the USACE, BCDC, and San Francisco Bay RWQCB within 90 days of restoring all of the on-site wetlands The as-built drawings will be prepared at an appropriate scale and will indicate:
final site elevations at the wetland restoration site;
aerial extent of restored wetland (in plan view);
location of photo-documentation stations and reference sites;
generalized locations of initial plug plantings (shown as polygons); and
other pertinent features.
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Chapter 4 Maintenance during the Monitoring Period
LGS will begin a plant maintenance period following the regulatory agencies’ acceptance of all initial wetland restoration construction activities. LGS or its designated contractor will maintain the mitigation site on an as-needed basis during plant establishment for up to a 5-year period (or less if success criteria have been met) following initial plant installation. The maintenance period, described in this chapter, coincides with the performance monitoring period described in Chapter 2.
Maintenance Activities
Routine maintenance will be required for the restored habitats. The planting and seeding areas will be monitored during the maintenance period. If remedial measures are identified as a result of performance monitoring, LGS will implement those measures during the maintenance period, in coordination with the regulatory agencies.
Maintenance activities during the monitoring period will include the following:
supplemental irrigation needs,
weed management,
plant replacement,
general site maintenance and repairs, and
preparation of as-maintained drawings.
These activities are described in the following sections.
Expected Maintenance Activities
Successful brackish marsh habitat restoration is contingent on proper hydrological functioning and water management. The design site elevations (relative to off-site control points) will be maintained throughout the maintenance period, which will help ensure proper site hydrological functioning and also help
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ensure that brackish marsh vegetation is successfully established on site. No other maintenance actions are anticipated.
Irrigation
Supplemental irrigation of brackish marsh vegetation should not be required. However, to further ensure proper plant establishment, plug plantings will be monitored for signs of water stress. Water stress would include such signs as plant die-off, wilted leaves, and lack of regrowth.
Throughout the establishment period, the revegetation contractor will monitor the plants for signs of water stress, and in the unlikely event that water stress is observed, supplemental irrigation will be applied as-needed to maintain the plantings. Water will be applied as required every week during the dry season (June to October) at an approximate rate of 2 gallons per planting plug. Water may be applied with a water truck or preferably hand-applied with a truck- mounted water tank and hose. Water will not be applied at a rate that will cause erosion, damage plants, or create runoff.
Water Source
As described above, supplemental irrigation is not anticipated for this project. In the unlikely event that supplemental irrigation is needed to ensure successful vegetation establishment, LGS will provide water via a water truck.
Weed Management
Periodic removal of invasive plants and/or competing weedy vegetation will be required during the 5-year maintenance period. Removal techniques may include manual, mechanical, or chemical methods. Selected methods will not damage installed plants or result in a discharge, other than incidental fallback, to WUS.
One invasive species, common reed, was detected on site. This species is common in and near freshwater, brackish and alkaline wetlands in the temperate zones worldwide. Common reed is considered a problem when and where stands appear to be spreading while other species typical of the plant community are diminishing. Disturbances or stresses such as alteration of the natural hydrologic regime, grading, dredging, and increased sedimentation can result in invasion and problematic spread of common reed.
For these reasons, during the maintenance period, any common reed detected within the restoration site will be hand treated (spot-sprayed) with Rodeo, a water solution of the isopropylamine salt of glyphosate that is commonly used for common reed control. If the revegetation contractor chooses to use pesticides, their use will be approved by the project manager or restoration ecologist and
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performed by a licensed pesticide applicator. Chemical control application shall meet all federal and state laws and federal, state, and local health and water quality regulations, as well as labeling instructions.
Any additional invasive plants detected within the wetland restoration site will be removed around the plug plantings. Invasive plants such as perennial pepperweed (Lepidium latifolium) are known to invade the drier edges of brackish marsh habitats and may infest the restoration site or the temporary impact site in the future. Any invasive plants encountered within the restoration site will be removed manually at least two times per year throughout the maintenance period.
Native herbaceous vegetation that is planted or naturally colonizes the restoration site will be retained.
Replacement Planting
No replacement plantings are anticipated because plug plants will be installed at a relatively high density. Most of the species planted are rhizomatous in nature and are expected to expand vegetatively. The plug plantings will be inspected during the performance monitoring visits to determine whether replacement plantings will be required to meet the success criteria.
If replacement plantings are required, the replacement plantings may be the same species or other brackish marsh species that are determined to be more suitable for micro-site conditions. Replacement plantings will include planting a sufficient number of individuals so that the cover of living plant material meets or exceeds the success criteria. Replacement plants will be installed according to the original plant installation methods.
During each year of the maintenance period, any replacement plantings required based on the results of the annual vegetation monitoring surveys will be provided, installed, and maintained by LGS or an authorized representative. The annual monitoring reports will identify the causes of plant mortality and any remedial measures that may be required. For example, if a particular species has a high mortality rate, a determination will be made about the cause of plant mortality and whether replacement by another species is warranted.
General Site Maintenance and Repairs
LGS or its designated contractor will maintain the fence and signs around the mitigation site and access road to the site.
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Lodi Gas Storage, L.L.C. Chapter 4. Maintenance during the Monitoring Period
Maintenance Inspections
LGS or its designated representative will conduct reconnaissance-level inspections of the wetland restoration site to identify any site issues and determine any necessary corrective actions. The wetland restoration site will be inspected for excessive erosion, grazing impacts, vandalism, or other site problems that may affect the wetland restoration effort and to identify possible repairs or remedial measures. Maintenance inspection visits will be conducted at least twice a year with an emphasis on visiting after a major rainstorm, if possible. If remediation is required because of flooding, fire, vandalism, or other damage, LGS will confer with the appropriate regulatory agencies on the appropriate level of remediation and implement the agreed-upon actions.
Proposed Monitoring Reports As-Maintained Drawings
During the monitoring period, a set of as-maintained drawings will be kept to record any site changes that occurred that modified the original site conditions described in the conceptual planting plan (e.g., changes planting densities or spacing).
Final as-maintained drawings will be completed and submitted to the appropriate regulatory agencies within 90 days of completion of the maintenance period.
Annual Reports
LGS will prepare an annual monitoring report and submit it to the regulatory agencies by December 30 of each monitoring year. Chapter 2 provides specific information on the content of the monitoring report.
Potential Contingency Measures
The purpose of this HMMP is to ensure that the targeted physical and ecological functions are achieved. Remedial actions provide a mechanism for modifying the mitigation/enhancement program if the mitigation site:
continually does not achieve the success criteria during Years 1 through 3, or
does not achieve the success criteria in Year 5.
LGS will seek approval from the appropriate regulatory agencies (e.g., USACE) for the most suitable remedial measures, based on site conditions. Remedial
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measures must be approved by the appropriate regulatory agencies (e.g., USACE) prior to implementation. Remedial measures will be developed based on the qualitative and quantitative monitoring results. To develop remedial measures, LGS will evaluate why a specific performance standard or success criterion was not achieved and determine the most effective remedy.
Remedial measures may include (but are not limited to) the following actions.
Regrading the site to reduce or increase site elevation, change hydrological functions, or increase/decrease the duration of ponding and /or soil saturation from surface water and/or groundwater.
Replanting areas that have lower than allowed vegetative cover. Replanting may include interplanting additional plugs if the original plug plantings are not spreading fast enough to achieve stated vegetation goals by Year 5 of the project. Replanting may also include introduction of additional species if the site species richness does not match adjacent reference sites.
Fencing the site to exclude livestock or moderate grazing levels.
Conduct additional invasive plant control actions (manual, mechanical, or chemical).
Providing supplemental irrigation if plug planting die-off is higher than anticipated in Years 1–3.
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Chapter 5 Completion of Mitigation
Notification of Completion
LGS will notify the appropriate regulatory agencies (e.g., USACE, BCDC, RWQCB, and CPUC) when the success criteria have been met. A map of the mitigation site and the annual monitoring report will be furnished with the notification to provide documentation to the agencies that the mitigation requirements have been completed.
Confirmation of Completion
LGS will provide for a site tour of the completed wetland restoration site. Based on the site visit, the regulatory agencies (as identified previously) will confirm that the mitigation site has met the success criteria and will provide LGS with written confirmation that its mitigation obligations have been met.
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Chapter 6 Contingency Measures
Initiating Procedures
At the end of the 5-year monitoring period, if the success criteria are not met, LGS will submit to the agencies an analysis of the causes of failure. If determined necessary by the agencies, LGS will propose remedial actions for agency approval. Alternatively, if it can be inferred from performance monitoring data that a sufficient portion of the mitigation site cannot be restored successfully, the contingency procedures discussed below may be implemented.
Alternative Locations for Contingency Mitigation
If mitigation cannot be successfully achieved at the intended mitigation site, LGS will seek approval from the appropriate regulatory agency for any proposed remedial measures.
Funding Mechanism for Contingency Mitigation
LGS will fund a contingency mitigation effort only if the proposed on-site mitigation does not meet the success criteria by the end of the 5-year monitoring period. The cost of contingency mitigation is expected to be comparable to the current approximate mitigation bank costs required for seasonal wetland mitigation (i.e., approximately $75,000 per acre).
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Chapter 7 Long-Term Management
Property Ownership
LGS currently has a long-term lease to operate the existing natural gas facility (Well W5) with the property owners (Christopher and Lisa Wohn, 2673 Shiloh Road, Suisun City, CA 94585).The Wohns will remain the property owners of the mitigation site following completion of the mitigation monitoring. Management Plan
Vegetation in the restored wetlands and channels will be monitored annually during years 1 through 5 (Chapter 2). Monitoring will be suspended in year 5 if the project meets success criteria and has been signed-off by the appropriate regulatory agencies. In the unlikely event that the restored wetlands and channels do not achieve the success criteria in year 5, LGS will consult with the resources agencies on appropriate additional monitoring or remedial measures.
Management Approach
No long-term management is anticipated for the brackish marsh habitat. This area will be monitored for the presence of invasive nonnative plants during the 5-year monitoring period. If invasive specifies are determined to be problematic to native plant establishment and/or survival at the end of the 5-year monitoring period, additional removal or control activities may be implemented beyond the 5-year monitoring period by LGS.
Site Protection
As stated above, the restored marsh is not anticipated to require long-term management. If remedial measures are necessary beyond the initial re- establishment period, LGS will continue to be responsible for any such measures for the duration of its lease term. For long-term protection, the restored marsh will be subject to regulatory protection by the BCDC and other regulatory agencies because it is located in the Suisun Marsh Primary Management Area.
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Lodi Gas Storage, L.L.C. Chapter 7. Long-Term Management
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Chapter 8 References Cited
Bates, L. 1977. Soil Survey of Solano County, California. USDA Soil Conservation Service in cooperation with the University of California Agricultural Experiment Station. Washington, DC: U.S. Government Printing Office.
Environmental Laboratory. 1987. Corps of Engineers Wetlands Delineation Manual. (Technical Report Y-87-1.) Vicksburg, MS: U.S. Army Waterways Experiment Station.
Jones & Stokes. 2007. Preliminary delineation of waters of the United States, including wetlands, for the Kirby Hills Natural Gas Storage Facility – Phase II. Solano County, California. May.
U.S. Army Corps of Engineers. 2004. Mitigation and Monitoring Proposal Guidelines. December. Special Public Notice. U.S. Army Corps of Engineers, Sacramento and San Francisco Districts.
U.S. Army Corps of Engineers. 2006. Interim Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Arid West Region. J. S. Wakeley, R. W. Lichvar, and C. V. Noble (eds.). (ERDC/EL TR-06-16.) Vicksburg, MS: U.S. Army Engineer Research and Development Center.
U.S. Environmental Protection Agency. 2007. Surf Your Watershed. Available:
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