Attachment C
Addendum to Final Negative Declaration IP No. 06-493/IP No. 06-493S
SAN JUAN CREEK AND TRABUCO CREEK FLOOD WALL
Orange County Public Works 300 North Flower Street Santa Ana, CA 92702-4048
Prepared by:
Keeton Kreitzer Consulting 180 South Prospect Avenue, Suite 104A Tustin, CA 92780
August 2011
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ADDENDUM TO FINAL NEGATIVE DECLARATION IP NO. 06-493/IP NO. 06-493S
SAN JUAN CREEK AND TRABUCO CREEK FLOOD WALL
Prepared for:
County of Orange Orange County Public Works 300 North Flower Street Santa Ana, CA 92702-4048 Contact: Lisa Cibellis (714) 647-3918
Prepared by:
Keeton Kreitzer Consulting 180 South Prospect Avenue, Suite 140A Tustin, CA 92680 Contact: Keeton K. Kreitzer, Principal (714) 665-8509
AUGUST 2011
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DRAFT TABLE OF CONTENTS
SAN JUAN CREEK AND TRABUCO CREEK FLOOD WALL COUNTY OF ORANGE
TABLE OF CONTENTS
Page
1.0 INTRODUCTION AND PURPOSE...... 1-1
1.1 CEQA Compliance ...... 1-1 1.2 Decision Not to Prepare a Subsequent EIR ...... 1-1 1.3 Use of an Addendum ...... 1-3
2.0 PROJECT DESCRIPTION...... 2-1
2.1 Project Location...... 2-1 2.2 Background...... 2-1 2.3 Original Project ...... 2-1 2.4 Proposed Project Description ...... 2-3 2.5 Project Phasing ...... 2-11 2.6 Permitting Agencies ...... 2-11
3.0 ENVIRONMENTAL ANALYSIS ...... 3-1
3.1 Land Use and Planning...... 3-1 3.2 Agriculture and Forestry Resources...... 3-2 3.3 Population and Housing...... 3-3 3.4 Geology and Soils ...... 3-3 3.5 Hydrology and Drainage ...... 3-5 3.6 Water Quality...... 3-6 3.7 Transportation/Traffic ...... 3-7 3.8 Air Quality ...... 3-9 3.9 Greenhouse Gas Emissions...... 3-12 3.10 Noise ...... 3-13 3.11 Biological Resources...... 3-15 3.12 Aesthetics ...... 3-18 3.13 Cultural/Scientific Resources...... 3-20 3.14 Recreation...... 3-20 3.15 Mineral Resources ...... 3-21 3.16 Hazards and Hazardous Materials...... 3-21 3.17 Public Services ...... 3-22 3.18 Utilities ...... 3-23 3.19 Conclusions ...... 3-24
Addendum to the Final MND San Juan Creek/Trabuco Creek Flood Wall August 2011
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DRAFT TABLE OF CONTENTS
LIST OF TABLES
Page
2.5-1 Proposed Phasing...... 2-11 3.1-1 Relevant Goals and Policies...... 3-2 3.8-1 De Minimis Levels for Criteria Pollutants ...... 3-10 3.8-2 Cumulative Daily Construction Emissions ...... 3-11 3.19-1 Summary of Environmental Impacts ...... 3-25
LIST OF EXHIBITS
Page
2-1 Project Location...... 2-2 2-2 Proposed Improvements...... 2-4 2-3 Phases 7 & 8 - Proposed Trabuco Creek Flood Wall Typical Cross Section ...... 2-6 2-4 Phases 7 & 8 - Proposed Trabuco Creek Flood Wall Proposed Detail...... 2-7 2-5 Phases 4 & 5 - Proposed San Juan Creek Reinforced Concrete Cap Typical Section ...... 2-8 2-6 Phases 4 & 5 - Proposed San Juan Creek Reinforced Concrete Cap Section Detail ...... 2-9 2-5 Visual Simulation - Proposed Flood Wall at Confluence...... 2-10
Addendum to the Final MND San Juan Creek/Trabuco Creek Flood Wall August 2011
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DRAFT CHAPTER 1.0 – INTRODUCTION AND PURPOSE
1.0 INTRODUCTION AND PURPOSE
1.1 CEQA Compliance
The County of Orange is the lead agency under the California Environmental Quality Act (CEQA) for the proposed San Juan Creek/Trabuco Creek Flood Wall (the “Project”). In accordance with Section 15164(a) of the CEQA Guidelines, Addendum to an EIR or Negative Declaration, this Addendum to the San Juan Creek/Trabuco Creek Flood Control Improvements (IP No. 06-493) has been prepared by the Orange County Flood Control District (OCFCD). Section 15162(a) of the State CEQA Guidelines states the following with respect to an Addendum to an EIR:
(a) The lead agency or responsible agency shall prepare an addendum to a previously certified EIR if some changes or additions are necessary but none of the conditions described in Section 15162 calling for preparation of a subsequent EIR have occurred.
On April 15, 2008, the OCFCD approved the Mitigated Negative Declaration (IP06-493) for the San Juan Creek/Trabuco Creek Flood Control Improvements (the “Final MND”) for the project described in the Project Description of the Final MND (the “Original Project”). Subsequently, the County of Orange has proposed to revise the Original Project to enhance the flood protection provided by the San Juan Creek and Trabuco Creek Flood Control Channels previously approved by Orange County Board of Supervisors in 2008. The proposed modifications include the inclusion of a two- to four-feet high "flood wall" atop of the existing and proposed concrete steel sheet pile caps, which will provide the required FEMA freeboard needed to remove the adjacent areas from the flood plain. Pursuant to the analysis contained in this addendum, the OCFCD has determined that the proposed modifications to the Original Project do not require preparation of a Subsequent or supplemental EIR.
1.2 Decision Not To Prepare a Subsequent EIR
The County of Orange, as lead agency, has determined that the proposed modifications to the Original Project do not require the preparation of a subsequent or supplemental EIR. Sections 15162 and 15163 of the State CEQA Guidelines mandate that:
Section 15162. Subsequent EIRs and Negative Declarations
(a) When an EIR has been certified or a negative declaration adopted for a project, no subsequent EIR shall be prepared for that project unless the lead agency determines, on the basis of substantial evidence in the light of the whole record, one or more of the following:
(1) Substantial changes are proposed in the project which will require major revisions of the previous EIR or negative declaration due to the involvement of new significant environmental effects or a substantial increase in the severity of previously identified significant effects;
(2) Substantial changes occur with respect to the circumstances under which the project is undertaken which will require major revisions of the previous EIR or Negative Declaration due to the involvement of new significant environmental
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DRAFT CHAPTER 1.0 – INTRODUCTION AND PURPOSE
effects or a substantial increase in the severity of previously identified significant effects; or
(3) New information of substantial importance, which was not known and could not have been known with the exercise of reasonable diligence at the time the previous EIR was certified as complete or the Negative Declaration was adopted shows any of the following:
(A) The project will have one or more significant effects not discussed in the previous EIR or negative declaration;
(B) Significant effects previously examined will be substantially more severe than shown in the previous EIR;
(C) Mitigation measures or alternatives previously found not to be feasible would in fact be feasible, and would substantially reduce one or more significant effects of the project, but the project proponents decline to adopt the mitigation measure or alternative; or
(D) Mitigation measures or alternatives which are considerably different from those analyzed in the previous EIR would substantially reduce one or more significant effects on the environment, but the project proponents decline to adopt the mitigation measure or alternative.
Section 15163 Supplement To an EIR:
(a) A lead or responsible agency may choose to prepare a supplement to an EIR rather than a subsequent EIR if:
(1) Any of the conditions described in Section 15162 would require the preparation of a subsequent EIR, and
(2) Only minor additions or changes would be necessary to make the previous EIR adequately apply to the project in the changed situation.
(b) The supplement to the EIR need contain only the information necessary to make the previous EIR adequate for the project as revised.
(c) A supplement to an EIR shall be given the same kind of notice and public review as is given to a draft EIR under Section 15807.
(d) A supplement to an EIR may be circulated by itself without recirculating the previous draft or final EIR.
(e) When the agency decided whether to approve the project, the decision-making body shall consider the previous EIR as revised by the supplemental EIR. A finding under Section 15091 shall be made for each significant effect shown in the previous EIR as revised.
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DRAFT CHAPTER 1.0 – INTRODUCTION AND PURPOSE
The potential environmental consequences of the proposed modifications to the San Juan Creek/Trabuco Creek Flood Control Channel have been thoroughly analyzed with respect to the conditions cited above. Based on an analysis of the proposed modifications to the Original Project, no new significant environmental impacts would occur, nor would the severity of impacts previously identified substantially increase. Nor is there any new information that suggests that mitigation measures or alternatives previously found not to be feasible would in fact be feasible, and would substantially reduce one or more significant effects of the project, but the project proponents decline to adopt the mitigation measure or alternative; or that mitigation measures or alternatives which are considerably different from those analyzed in the previous Initial Study/Mitigated Negative Declaration would substantially reduce one or more significant effects on the environment, but the project proponents decline to adopt the mitigation measure or alternative.
The County of Orange has determined, on the basis of substantial evidence in the analysis presented in Chapter 3.0 of this Addendum, that none of the conditions identified in Section 15162 of the State CEQA Guidelines have occurred. Therefore, an addendum, pursuant to Section 15164 of the State CEQA Guidelines, has been prepared and submitted to the County’s decision-makers, along with the Final MND for the San Juan Creek/Trabuco Creek Flood Control Channel Improvements, for consideration prior to taking action to approve the proposed Amendment to the Original Project.
1.3 Use of an Addendum
This Addendum has been prepared pursuant to Section 15164(a) of the State CEQA Guidelines that state:
(a) The lead agency or responsible agency shall prepare an addendum to a previously certified EIR if some changes or additions are necessary but none of the conditions described in Section 15162 calling for preparation of a subsequent EIR have occurred.
The revisions to the Original Project described in this Addendum to the Final MND are considered to be a refinement of the approved plan that will not require any major revisions to the Final MND. Most importantly, the proposed revisions have been determined to be minor and, further, will not result in significant new or more severe impacts and/or the requirement for additional mitigation measures. As a result, the proposed changes do not require the preparation of a subsequent MND or supplemental MND.
The Orange County Board of Supervisors and, if necessary, other responsible agencies identified in the Final MND will consider the information contained in this Addendum along with the Final MND prepared for the San Juan Creek/Trabuco Creek Flood Control Improvements prior to making a final decision on the proposed revisions to the Original Project, which revisions propose to include a flood wall to provide additional flood protection to properties located adjacent to the subject flood control channels.
Addendum to the Final MND San Juan Creek/Trabuco Creek Flood Wall July 2011
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DRAFT CHAPTER 2.0 – PROJECT DESCRIPTION
2.0 PROJECT DESCRIPTION
2.1 Project Location
The proposed project, which includes the construction of a flood wall above portions of Trabuco Creek and San Juan Creek within the eight (8) phases of the flood control improvements (i.e. SSP project) previously approved for San Juan and Trabuco Creeks, is located in the City of San Juan Capistrano (Phases 1 through 5, 7 and 8) and The City of Dana Point (Phase 6). The project location is illustrated on Exhibit 2-1.
2.2 Background
Surface erosion, land use, and natural forces have negatively affected water flow and drainage patterns; these factors have created the potential of flooding in certain areas of the San Juan Creek and Trabuco Creek. The City of San Juan Capistrano and the Federal Emergency Management Agency (FEMA), along with private sector partners have joined forces to modernize the flood mapping. As a result, new flood maps were adopted effective December 2009, detailing current data on county flood hazards. In the process, FEMA has redefined the San Juan Creek and Trabuco Creeks flood plains to delineate the flood hazard areas that are prone to flooding. This action has placed many more homes and businesses within the 100-year flood plain that were not previously within the flood plain. The proposed flood wall is intended to provide enhanced flood protection to the existing residences and businesses currently located within the flood plain delineated by FEMA and would not significantly increase the potential for additional, unintended growth and development because the area of potential effect is extensively developed. The proposed improvements (i.e., reinforced concrete cap, flood wall, and fence), are consistent with existing long-term improvement plans for the Trabuco Creek/San Juan Creek flood control system and to provide flood protection to the adjacent areas within the area.
Orange County Flood Control District (OCFCD) staff analyzed the hydraulics of the creeks for both the FEMA 100-year discharge and the OCFCD ultimate 100-year design discharge. With a slight adjustment (i.e., addition of flood walls) to the original project scope, OCFCD has determined that the existing, adopted 100-year FEMA discharge would be contained with adequate freeboard. With the additional structural stability the steel sheet pile will provide, coupled with the construction of the proposed flood walls, the existing floodplain (or parts thereof) could potentially be entirely removed.
2.3 Original Project
When proposed in 2006, the original flood control improvement project consisted of driving steel sheet piles (SSP) along the top of the embankment to a depth of approximately 48 feet along 13,760 linear feet of San Juan Creek Channel (L01) and 10,200 linear feet of Trabuco Creek Channel (L02). The steel sheet piles are driven in sets of four pairs having a staggered depth consisting of three 48-foot long SSP pairs followed by one 35-foot long SSP pair. Other improvements to the channels included the removal and/or alteration of some grouted or loose riprap stones/rocks and other subsurface obstructions that could potentially interfere with the SSP.
The original project encompassed eight (8) phases, extending from Sta. 61+00 and Sta. 141+55 in Trabuco Creek and San Juan Creek, respectively to Sta. 51+00 in downstream (i.e., south) in San Juan Creek, south of the confluence of the two creeks.
Addendum to the Final MND San Juan Creek/Trabuco Creek Flood Wall June 2011
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DRAFT CHAPTER 2.0 – PROJECT DESCRIPTION
Exhibit 2-1 Project Location
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DRAFT CHAPTER 2.0 – PROJECT DESCRIPTION
2.4 Proposed Project Description
OCFCD has proposed to install a two to four feet high flood wall (32-inch "typical" split face block wall) atop of existing and proposed concrete steel sheet pile caps, which will provide the required FEMA freeboard needed to remove the adjacent areas from the flood plain. The recent and ongoing sheet pile improvements meet FEMA levee structural criteria and, as previously described, are consistent with improvements necessary to convey the OCFCD ultimate 100-year discharge.
The OCFCD is proposing to improve portions of San Juan Creek and Trabuco Creek by constructing a flood wall (Phases 7 & 8) and reinforced concrete cap (Phases 4 & 5) as described below.
Trabuco Creek (L02) Flood Wall
▪ Station 17+25 to Station 61+00 (Phases 7 & 8) ▪ 32-inch high tan/buff split faced block wall ▪ Cement mortar finish cap or precision finish cap ▪ 42-inch guard cable fence (Modified OC Public Works Standard Plan 1413)
The proposed flood walls will be constructed along the eastern and western levees of Trabuco Creek. These walls will serve as a flood wall/safety barrier and will be a combination of reinforced masonry block with approximately three and one-half feet high safety fence on top. The alignment of the wall will run along the top of the maintenance road at approximately 1 foot from the inner channel hinge (refer to Exhibit 2-2).
Three preliminary material choices were identified for the flood wall, including: (1) split face block; (2) slump block with sack finish; and (3) decorative cast in place concrete. The San Juan Capistrano Planning Commission approved the tan split face block wall with a modified cable guard (Modified OC Public Works Standard Plan 1413) as illustrated in Exhibit 2-6. The reinforced concrete cap and steel sheet pile will be exposed above ground a total of 32 inches.
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DRAFT CHAPTER 2.0 – PROJECT DESCRIPTION
Exhibit 2-2 Proposed Improvements
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DRAFT CHAPTER 2.0 – PROJECT DESCRIPTION
Exhibit 2-3 illustrates the flood wall improvements proposed for Phases 7 and 8 on the east and west levees of Trabuco Creek. As indicated in that exhibit, the 32-inch flood wall will extend vertically above the concrete sheet pile cap over the steel sheet pile previously constructed behind the existing channel bank adjacent to the existing bike path/maintenance road. The 42-inch high guard cable fence will extend above the flood wall. Similarly, the flood wall and fence on the west side of the channel downstream of the pedestrian bridge would be constructed above the existing concrete sheet pile cap overlying the steel sheet pile reinforcing the channel bank. The details of the flood wall and fence are illustrated in Exhibit 2- 4. As can be seen, the 32-inch flood wall will be constructed of four levels of split face block (32 inches high). The 42-inch high fence above the flood wall will be anchored by galvanized line posts approximately 10 feet on center. The lower half of the guard cable fence is characterized by 1/4 inch cables spaced three inches apart horizontally to a height of 21 inches above the top of the flood wall. A single 1/4 inch cable is located 42 inches above the top of the flood wall below the anchor post of each of the post supporting the cables.
San Juan Creek (L01) Exposed Steel Sheet Pile and Reinforced Concrete Cap
▪ Station 66+00 to Station 113+00 (Phases 4 & 5) ▪ 42-inch guard cable fence (Modified OC Public Works Standard Plan 1413) ▪ Reinforced concrete cap and steel sheet pile (exposed above ground a total of approximately 32 inches)
The typical section for the reinforced concrete cap that is proposed above the exposed steel sheet pile in Phases 4 and 5 is illustrated in Exhibit 2-5. As can be seen in the typical section, the reinforced concrete cap will be placed atop the existing sheet pile that is intended to protect the integrity of the channel bank. The reinforced concrete cap is proposed only along the east side of the channel bank. As indicated in Exhibit 2-6, the concrete cap is proposed to cover approximately 28 inches of the nearly 32 inches of the steel sheet pile that extends above the top of the levee. That exhibit also shows the location and height of the wall and fence, which extend above the concrete cap.
Exhibit 2-7 illustrates a visual simulation (i.e., Photoshop image) of a portion of the proposed flood wall for the confluence curve that shows the relationship of the San Juan Creek bikeway to the adjacent creek and flood wall. As indicated in that image, the proposed 32-inch flood wall will be constructed of a split face block and will be tan/buff in color. In addition, the modified cable guard fence extends above the wall by 42 inches.
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Exhibit 2-3 Phases 7 & 8 – Proposed Trabuco Creek Flood Wall Typical Cross Section
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Exhibit 2-4 Phases 7 & 8 – Proposed Trabuco Creek Flood Wall Section Detail
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Exhibit 2-5 Phases 4 & 5 – Proposed San Juan Creek Reinforced Concrete Cap Typical Cross Section Page 15 of 45 Attachment C
Exhibit 2-6 Phases 4 & 5 – Proposed San Juan Creek Reinforced Concrete Cap Proposed Detail Page 16 of 45 Attachment C
Exhibit 2-7 Visual Simulation - Proposed Flood Wall at Confluence Page 17 of 45 Attachment C
DRAFT CHAPTER 2.0 – PROJECT DESCRIPTION
2.5 Project Phasing
The anticipated phasing schedule for the proposed flood wall will occur over a three-year period, beginning in February 2012 with Phase 7 and extending through March 2015 with the completion of Phase 8. Phases 4 and 5 of the proposed improvements are scheduled to be constructed between February and May 2013. The proposed Phasing for the San Juan Creek Flood Wall is reflected in Table 2.5-1.
Table 2.5-1
Proposed Phasing San Juan Creek/Trabuco Creek Flood Wall
Approximate Start Approximate Approximate Phase Date Completion Date Duration Phase 71 Feb 2012 Sept 2012 130 Days Phases 4&51 Feb 2013 May 2013 60 Days Phase 81 Mar 2015 May 2015 40 Days
1The walls for phases 4 & 5 and 7 & 8 will be constructed as part of the remaining phases of the levee protection project.
2.6 Permitting Agencies
The OCFCD is the agency that is responsible for carrying out the proposed improvements. The project will require approval by the Board of Supervisors of the OCFCD.
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DRAFT CHAPTER 3.0 – ENVIRONMENTAL ANALYSIS
3.0 ENVIRONMENTAL ANALYSIS
The purpose of Chapter 3.0 of this Addendum to the San Juan Creek/Trabuco Creek Flood Control Improvements Final MND is to provide an analysis of the potential environmental consequences that are anticipated to occur as a result of implementation of that portion of the Amended Project that was not analyzed in the Final MND. Specifically, the analysis contained in this chapter includes a discussion of the impacts associated with the development of the proposed flood wall and any impacts that result from that addition, as described in Chapter 2.0 (Project Description).
3.1 Land Use and Planning
The proposed project is located along the downstream reaches of Trabuco Creek (from Ramos Street to the confluence with San Juan Creek) and San Juan Creek (from Camino Capistrano to the Dana Point City boundary in the City of San Juan Capistrano and a small reach of San Juan Creek in the City of Dana Point (from the San Juan Capistrano boundary to Stonehill Drive). Existing land uses adjacent to and in the vicinity of Trabuco Creek Channel within the project limits encompasses a mix of residential and commercial, and light industrial uses. The portion of the San Juan Creek located within Dana Point (Phase 6) is bounded by residential development. Project implementation includes the construction of a flood wall along both sides of the channels that is intended to provide additional flood protection. The flood wall would be two to four feet high and would be located atop of existing and proposed concrete caps of the steel sheet pile wall system, which will provide the required FEMA freeboard needed to remove the adjacent areas from the flood plain. While the existing San Juan and Trabuco Creeks presently physically divide portions of the urban area, that is an existing condition, not a result of the project. The construction activity, which is temporary, would result in the placement of that flood wall along the existing channel segments, which would not result in physical divisions in an established community. The project includes only improvements (i.e., a 2- to 4-foot flood wall) along a segment of Trabuco Creek and San Juan Creek that will not result in any additional physical divisions that would adversely affect established communities and/or neighborhoods (i.e., divide or physically disrupt the integrity of the existing communities) within the area. The flood wall will be located on the tops of the existing levees of the affected creeks and not within any area that has been developed with residential or other urban features. Therefore, no significant impacts are anticipated and no mitigation measures are required.
Implementation of the proposed project will not conflict with any zoning or general plan designations or policies. Although the County is not subject to the land use regulations of the Cities, this is an OCFCD project rather than a County project. Several policies have been adopted by San Juan Capistrano and Dana Point that address the provision of adequate infrastructure. The proposed project would not conflict with policies adopted by the City. The proposed project is generally consistent with the relevant policies articulated in the San Juan Capistrano General Plan.
Implementation of the proposed project does not conflict with the adopted policies of the affected jurisdictions (i.e., City of San Juan Capistrano and Dana Point). The proposed flood wall will provide additional flood protection along Trabuco Creek and San Juan Creek, which is consistent with the policies of not only the Orange County General Plan but also those of the Cities of San Juan Capistrano and Dana Point which address flood protection. The respective goals and policies of the County of Orange and the two affected cities are noted below in Table 3.1-1.
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DRAFT CHAPTER 3.0 – ENVIRONMENTAL ANALYSIS
Table 3.1-1
Relevant Goals and Policies Proposed Flood Wall
City of San Juan Capistrano – Flood Plain Management Element Goal No. 1 Protect life and property from floodwaters Limit development within the floodplain to minimize risks to life and property and satisfy the flood Policy No. 1.1 insurance and other requirements of the Federal Emergency Management Agency (FEMA). Construct new flood protection improvements where determined necessary by the City, County, and Army Policy No. 1.3 Corps of Engineers.
City of Dana Point – Public Safety Element Goal No. 2 Reduce the risk to the community’s inhabitants from flood hazards. Policy No. 2.5 Continue to participate in the national flood insurance program. Cooperate with the Orange County Flood Control District to plan for and make needed improvements or Policy No. 2.6 modifications to San Juan Creek Channel to enable it to carry runoff from a 100-year storm.
County of Orange – Safety Element Goal No. 1 Provide effective and efficient flood protection throughout Orange County. To encourage and promote coordination between regional/local flood control agencies and the Policy No. 2 State/Federal agencies for optimum flood prevention programs and protection devices.
As indicated above, the stated goals and policies of San Juan Capistrano and Dana Point as well as the County of Orange are intended to reduce the potential flood hazard/risks to life and property. Furthermore, the policies encourage coordination between the Orange County Flood Control District (OCFCD) and local jurisdictions. To that end, the OCFCD has worked directly with the affected cities and designed the flood protection improvements to meet the parameters established by San Juan Capistrano and Dana Point. As a result, the project is consistent and compatible with the adopted plans and programs of the two affected cities and no significant land use conflicts would occur as a result of the additional improvements.
The affected reaches of Trabuco Creek and San Juan Creek are not located within either one of the County’s Natural Community Conservation Plan/Habitat Conservation Plan (NCCP/HCP) program areas. Therefore, the proposed flood wall project will not conflict with any of the applicable plans or policies adopted by the County of Orange and/or City of San Juan Capistrano related to the NCCP/HCP program. Furthermore, project implementation would not result in any short-term construction impacts (e.g., noise) that would affect sensitive avian species that may inhabit the channel bottom. Refer to the discussion in Section 11 (Biological Resources). No significant impacts on the NCCP or other conservation areas will occur as a result of the proposed project.
3.2 Agriculture and Forestry Resources
No Prime Farmland, Farmland of State or Local Importance, or Unique Farmland occurs within or in the vicinity of the site, which extends along Trabuco and San Juan Creeks. The site and adjacent areas are designated as “Urban and Built-up Land” and “Other Land” on the Orange County Important Farmland Map. Further, neither the site nor the adjacent areas are designated as prime, unique or important farmlands by the State Resources Agency or by either the Orange County General Plan or San Juan
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DRAFT CHAPTER 3.0 – ENVIRONMENTAL ANALYSIS
Capistrano General Plan. The San Juan Capistrano General Plan Land Use Element designates the area of San Juan and Trabuco Creeks as General Open Space (GOS)/Creek; the creeks are also zoned as open space. Therefore, there is no conflict with zoning for agricultural use, and the property and surrounding properties are not under a Williamson Act contract. No significant impacts are anticipated and no mitigation measures are required.
The project site is neither zoned nor designated as forestland. Trabuco and San Juan Creeks are improved as regional flood control facilities in south Orange County. No portion of the project area is designated as “forest land” by the City of San Juan Capistrano and, furthermore, the area does not support forest land/resources. Project implementation would not result in the conversion of any forestland subject to the Public Resources Code. No significant impacts are anticipated and no mitigation measures are required.
The project area is not being used for either agricultural or forestland purposes and, as indicated previously, is not designated as agricultural or forest land. The area surrounding the two affected flood control channels is developed with a variety of residential, industrial, and recreational uses. Therefore, no agricultural or forest uses exist on the site or within the site’s vicinity would be converted to non- agricultural or non-forest use. No significant impacts are anticipated and no mitigation measures are required.
3.3 Population and Housing
Project implementation includes only the incorporation of a flood wall along the San Juan Creek and Trabuco Creek flood control channels, which is intended to provide additional flood protection to development existing along the creeks. No residential or other development is proposed that would either increase population in the City of San Juan Capistrano or facilitate unanticipated growth, either in San Juan Capistrano or south Orange County. The flood wall proposed for the two flood control channels would extend along the tops of the channel banks, within the flood control right-of-way. The proposed improvements would not result in the displacement of existing residential dwelling units or other housing. Therefore, no replacement housing would be required. As indicated above, project implementation will not result in any loss of existing dwelling units. Therefore, the proposed flood wall, which will be located within the flood control channel right-of-way, will not displace any residents. As a result, displacement of residents will not occur and no other impacts to existing residents are anticipated. No significant impacts will occur and no mitigation measures are required.
3.4 Geology and Soils
The project site and environs are located in the seismically active southern California region within unincorporated Orange County (i.e., San Juan Capistrano/Dana Point). Seismic activity in the region and in the vicinity of the project area is associated with several active fault zones, including the Newport- Inglewood Fault Zone, San Andreas Fault Zone, San Jacinto Fault and other regionally active faults. Primary ground rupture or fault rupture is defined as the surface displacement, which occurs along the surface of a fault during an earthquake. There are no active faults or fault systems known to exist on or in the immediate vicinity of the project site. In addition, the project site is not within an Alquist-Priolo Earthquake Fault Zone as illustrated on the maps issued by the State Geologist for the area. Therefore, implementation of the proposed project (i.e., construction of the flood wall along reaches of Trabuco
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DRAFT CHAPTER 3.0 – ENVIRONMENTAL ANALYSIS
Creek and San Juan Creek) is not anticipated to expose people or structures to fault rupture during a seismic event. No significant impacts will occur and no mitigation measures are required.
As indicated above, the project area is located in a seismically active region. Although there are no active faults or fault systems known to exist on or in the immediate vicinity of the project site (and the site is not within an Alquist-Priolo Earthquake Fault Zone), it is subject to seismic shaking resulting from earthquakes occurring on one or more of the regional faults identified above. The Newport-Inglewood Fault is believed to be capable of producing an earthquake having a magnitude of 7.5. While low to moderate ground shaking is anticipated on the site and in the environs, this risk is no greater than for any other area within Southern California. In addition, no habitable structures are proposed. The proposed project is intended to implement the flood wall along portions of Trabuco Creek and San Juan Creek in order to provide an adequate level of flood protection associated with the 100-year flood event in the area that currently exists. The potential impacts resulting from ground shaking associated with seismic activity are minimized and are less than significant as a result of the design of the proposed improvements. No significant groundshaking impacts will occur as a result of project implementation and no mitigation measures are required.
Although the project site is located in an area that has a potential for stronger ground shaking, no habitable structures are proposed that would be subject to a potential for liquefaction or seismic-related ground failure. In addition, no excavation is necessary to implement the proposed improvements and the proposed flood wall is not within a slope or other feature that would be subject to potential landsliding. The proposed improvements are not subject to any other significant potential for landslides and/or mudslides. Therefore, no significant impacts are anticipated to occur as a result of project implementation.
Soil erosion occurs as a result of the action of wind and water. While wind erosion may have some localized significance, it is not a major natural hazard that would result in potentially significant effects because of the limited amount of soil that would be exposed as a result of project implementation. However, excavation of native soils is not required to implement the proposed flood wall. Therefore, potential impacts are anticipated to be less than significant and no mitigation measures are required.
While the project environs may have a potential for subsidence, no residential, commercial, or industrial development is proposed that would be subject to the effects of subsidence. The affected property (i.e., flood control right-of-way) does not contain any unique geologic or physical features that would preclude implementation of the flood control improvement project as proposed. As previously indicated, the site will be vulnerable to ground shaking; however, no significant impacts to structures will occur as no dwelling units or other structures are proposed. Potential impacts to unique geologic or other physical features are anticipated to be less than significant as a result of project implementation.
No habitable structures or other significant buildings are proposed that would be impacted by expansive soils. As indicated above, the proposed flood control improvements are intended to upgrade the existing, level of flood protection along the affected reaches of the two channels and to provide protection from 100-year storm flows occurring in the area based on FEMA requirements. Therefore, no potential significant impacts will occur as a result of project implementation.
The OCFCD is proposing to construct a flood wall on top of the channel banks of certain reaches of Trabuco Creek and San Juan Creek (refer to Exhibit 2-2). The improvements would not require the use of septic tanks and/or alternative wastewater disposal systems. Therefore, no significant impacts will occur as a result of project implementation.
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3.5 Hydrology and Drainage
The proposed improvements are intended to enhance flood protection along the affected reaches of Trabuco and San Juan Creeks in south Orange County. At the present time, areas adjacent these reaches are subject to inundation. Implementation of the proposed flood wall and related improvements will contain the current 100-year flood flows to the respective channel (i.e., Trabuco Creek and San Juan Creek), thereby eliminating areas currently subject to potential inundation from a flood hazard.
Although prior disturbance associated with earlier phases of the project has resulted in some landform alteration, potential erosion and/or siltation were addressed (e.g., construction BMPs required by the SWPPP for that project), implementation of the proposed flood wall does not require any excavation or grading that would expose native soils to the erosional effects of either wind or water. In addition, no siltation will occur. None of the construction activities associated with this project would cause either erosion or siltation off-site. No significant impacts are expected to occur and no mitigation measures are required.
No development or other landform alteration is proposed that would result in changes to the existing drainage pattern within the project environs. Neither San Juan Creek nor Trabuco Creek would be altered. Once the improvements (i.e., construction of the flood wall) are completed, they would not increase the rate or amount of surface runoff that would adversely affect the capacities of the existing storm drainage and/or flood control facilities to cause flooding. The proposed improvements are required to ensure that adequate protection of the adjacent properties is provided from the 100-year storm event along either channel. Therefore, no significant impacts are anticipated and no mitigation measures are required.
Project implementation includes only the construction of the flood wall on the levees above Trabuco Creek and San Juan Creek. Once completed, the improvements do not include any features or structures that would result in any increase in additional runoff associated with the proposed improvements, which would not change the surface runoff characteristics of the property. As a result, project implementation will not cause the capacity of any existing storm drainage/flood control channels that conveys surface runoff in storm events to be exceeded. It is possible that short-term pollution impacts may occur as a result of construction activities; however, specific measures/BMPs will be incorporated into the construction activities (as prescribed in the SWPPP prepared for the prior projects that have been approved to ensure that significant siltation and/or pollution associated with construction equipment is minimized. Therefore, no significant impacts are anticipated and no mitigation measures are required.
The proposed project does not include any housing that would be placed within the limits of a 100-year flood even of either Trabuco Creek or San Juan Creek. However, as previously indicated, the proposed flood wall is intended to provide additional flood protection to the homes and properties that exist along the southern limit of Trabuco Creek and San Juan Creek from the I-5 Freeway to Stonehill Drive. With the addition of the flood wall, adequate flood protection would exist based on the limits of the 100-year flood event identified by FEMA. No significant impacts are anticipated and no mitigation measures are required.
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No structures are proposed within any designated 100-year flood hazard area identified by the County of Orange or FEMA. Along with the Steel Sheet Pile (SSP) Improvement project previously approved by the County in 2008 to provide enhanced flood protection to the area, the proposed flood wall is intended to provide increased flood protection to structures and properties located in the levee above Trabuco Creek. Therefore, no impacts are anticipated as a result of project implementation.
As indicated above, project implementation will not result in the placement of any permanent habitable structures within an existing 100-year flood hazard area identified by the County of Orange. Project implementation does not include development that would expose either people or structures to potential flooding or other hazards resulting from the failure of a levee or dam. The potential impacts of these activities will not be significant.
The project area is not located in an area that is subject so seiches or tsunamis. A seiche involves the oscillation of a body of water in an enclosed basin, such as a reservoir, storage tank, or lake. No enclosed bodies of water are located in the immediate vicinity of the project area. A tsunami, commonly referred to as a tidal wave, is a sea wave generated by submarine earthquakes, major landslides, or volcanic action. The subject reaches of Trabuco Creek and San Juan Creek are located inland, away from the Orange County coastline. No development is proposed that would be adversely affected by either tsunami or seiche hazards. Implementation of the proposed project will not expose people or structures to seiches, tsunamis or mudflows. Therefore, no significant impacts will occur as a result of project implementation.
3.6 Water Quality
Trabuco Creek and San Juan Creek are major drainage courses in the City of San Juan Capistrano. These flood control channels carry surface water and runoff generated within the respective watersheds through the City and eventually discharge it into the Pacific Ocean. The confluence of Trabuco and San Juan Creeks is west of the I-5 Freeway. These creeks are the primary source of surface water in the City. Although there has been substantial urban development in the area, most of the San Juan Creek streambed has been left in its natural condition with natural banks and is characterized by riparian vegetation. Lower San Juan Creek in the project area has been modified for flood control with sides of concrete and rip-rap while maintaining a soft bottom. San Juan Creek is under the jurisdiction of the San Diego Regional Water Quality Control Board (RWQCB), which has identified a surface water quality problem in the San Juan Creek Basin. Under direction of the RWQCB the County has developed plans to address these issues.
Construction activities are necessary to implement the proposed flood wall; however, the proposed project does not include any changes in the impervious surfaces, including the addition of features (i.e., development) that would change either the rate or amount of runoff, or water quality characteristics of that runoff. The construction activities associated with project implementation will not result in any significant impacts to water quality with the implementation of the standard procedures that must be implemented by the County. No potential impacts to water quality beyond those previously analyzed in the prior analysis conducted for the original project (i.e., sheet pile system) would occur. Nonetheless, as previously indicated, BMPs included in the SWPPP for the SSP project that is currently underway, which are intended to ensure that construction activities do no adversely affect water quality, will also be implemented as necessary for the proposed flood wall.
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The proposed project would not adversely affect groundwater recharge because no excavation is required. Project implementation will not violate any water quality standards or waste discharge requirements. No significant water quality impacts are anticipated; however, it is possible that some discharge of sediments may occur into surface waters entering both San Juan Creek and Trabuco Creek as a result of the construction activities. However, the effect of any discharges on surface water quality would be avoided or minimized through the implementation of BMPs and, therefore, less than significant. The BMPs would be implemented in accordance with the conditions imposed on the previously approved SSP Improvement Project to comply with current regulatory requirements. Conditions that will be implemented by the OCFCD to address water quality impacts associated with the sheetpiling project are those prescribed in the Standard Specifications for Public Works Construction (“Green Book”), the project-specific “Plans and Special Provisions for Construction,” the general NPDES dewatering permit issued by the California Regional Water Quality Control Board, the general NPDES Permit for Construction Activities issued by the California Water Resources Control Board, and the Areawide Urban Stormwater Runoff Permit for Orange County issued by the California Regional Water Quality Control Board. In consideration of the nature of the proposed project and the implementation of the BMPs identified for the previously approved SSP Improvement project (i.e., preparation of a SWPPP), potential significant impacts that will occur as a result of the proposed project will be avoided or reduced to a less than significant level.
3.7 Transportation/Traffic
Traffic resulting from implementation of the proposed project is anticipated to occur only during the construction phase. The only vehicle trips generated by the proposed project include home to work trips of the construction workers, delivery of supplies and materials, and hauling of construction debris from the site. No significant incremental increases in traffic beyond that necessitated by the original project would occur. As previously indicated, temporary disruption along area streets can be expected due to mobilization of construction equipment and transport of construction materials; however, the proposed project-related traffic would not exacerbate that condition due to the limited number of trips associated with it. The proposed main access to the project is via the end of a paved portion of Alipaz Street where it terminates into an open space area. Trabuco Creek Channel is accessible through Paseo Adelanto to the east and the maintenance access road and Alipaz to the west via Del Obispo Street. The numbers of trips are very small and would occur during non-peak hours. In addition, temporary disruption of the maintenance road/bikeway is also anticipated through the three-year construction period associated with the SSP and related channel improvements (i.e., flood wall, etc.). In order to ensure that construction impacts (i.e., disruption on area streets) are minimized, the OCFCD has prepared a Construction Management Plan and Traffic Control Plan that outlines construction activities that are anticipated to occur over a five-year phasing period of the previously approved SSP Improvement Project, which encompasses the proposed project. In those locations that would affect the maintenance road and bicycle trail, the County was also required to provide interim bicycle facilities during the construction phase to ensure that no disruption of the bicycle trail will occur. As required for the previously approved SSP Improvement project, a bicycle route detour will be provided subject to approval by the City of San Juan Capistrano as a result of the SSP Improvement Project previously approved by the County. No long-term traffic impacts will occur and no other mitigation measures are required.
As indicated above, no long-term traffic impacts will occur as a result of the proposed project. The relatively few trips generated by the proposed project are those of the construction workers, which will cease upon completion of the proposed flood wall. Although the proposed project, along with the SSP project currently underway, will affect the existing bicycle trail, necessitating its temporary rerouting, the
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proposed project will not conflict with any plan, ordinance or policy related to the provision of efficient circulation. No long-term impacts will occur to the bicycle trail, which will return to its designation alignment upon completion of the proposed flood control improvements. No significant impacts are anticipated and no mitigation measures are required.
With the minor exception of vehicle trips associated with maintenance of the flood control improvements, project implementation will not result in the generation of any long-term traffic. Therefore, neither potential individual or cumulative traffic and/or circulation impacts will occur as a result of the proposed project; no mitigation measures are required.
The proposed project does not include development that would generate vehicular traffic. Therefore, the flood wall would not conflict with any existing or proposed Congestion Management Program (CMP) policy or program related to level of service, transportation demand management, or other standards. No significant impacts are anticipated and no mitigation measures are required.
The OCFCD is proposing only to improve flood protection along selected reaches of the two affected creeks with the construction of a flood wall along the levees above Trabuco Creek and San Juan Creek in San Juan Capistrano and Dana Point. These improvements would not result in a change in air traffic patterns at John Wayne Airport (JWA) or other aviation facility in the area or region. Project implementation will not result in an increase in traffic levels or create a potential safety risk to/from air traffic. In addition, no development and/or other roadways are proposed that would result in an increase in potential hazards to traffic. No significant impact will occur and no mitigation measures are required.
Project implementation will not result in any changes to circulation in the project area. Vehicular access to the area is available via Del Obispo Street from the north and Stonehill Drive from the south. The proposed project does not include any component that would either change the access to the site or affect the existing access. All of the construction activities will occur within the limits of the flood control right-of-way of San Juan Creek and Trabuco Creek along the project limits. The limited number of construction vehicles that would access the levee where the improvements are proposed would not adversely affect emergency access. No significant impacts are anticipated and no mitigation measures are required.
Project implementation will not result in a long-term demand for parking. The flood wall project will only require short-term parking for construction workers during the construction phase; no long-term (i.e., permanent) parking is required and, therefore, no significant parking impacts are anticipated. Interim parking for construction workers will be provided in the vicinity of the project site during each phase of construction. Therefore, potential impacts will be less than significant and no mitigation measures are required.
The proposed project encompasses only infrastructure improvements (i.e., construction of the flood wall) that provided enhanced flood protection along the affected reaches of San Juan Creek and Trabuco Creek. No development is proposed that would necessitate the inclusion of alternative plans and/or programs to accommodate alternative modes of transportation. Furthermore, project implementation would also not result in any significant growth-inducement because the proposed improvements are intended to provide an adequate level of flood protection for existing development within the existing flood plain. The majority of the project area is developed, with only limited potential for additional development adjacent to Phase 5 improvements in the south end of the City of San Juan Capistrano. While it is possible that the proposed improvements may induce some growth, it is limited to portions of the City of
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San Juan Capistrano where development is anticipated as reflected on the City's General Plan. Therefore, growth-inducing impacts are anticipated to be less than significant.
Project implementation is proposed to occur along the top of the channel bank of the two affected creeks, which may result in the impacts to the San Juan Creek Bikeway that currently exists along the creeks. These impacts are the same as those identified for the SSP Improvement project previously approved by the County, which necessitated the temporary relocation of the existing trails to ensure that these impacts are less than significant. During the construction phase of the proposed SSP project, which encompasses the proposed flood wall, the existing trail along the creeks has been temporarily relocated to ensure continuity of its use. Upon completion of the SSP project, the trail will be restored along the channel levees as designated on the County’s regional plans. No additional mitigation measures would be required beyond those already prescribed for the SSP Improvement Project previously approved by the County.
3.8 Air Quality
The proposed project includes only the construction of flood control improvements (i.e., flood wall) along reaches of Trabuco Creek and San Juan Creek in the Cities of San Juan Capistrano and Dana Point. Emissions that would be anticipated are those associated with the use of small construction equipment (gasoline-powered saws, etc.). However, these emissions will be very limited and would not be expected to exceed either South Coast AQMD significance thresholds or federal de minimis thresholds.
The U.S. Environmental Protection Agency published “Determining Conformity of General Federal Actions to State or Federal Implementation Plans; Final Rule,” in the November 30, 1995, Federal Register (40 CFR Parts 6, 51, and 93). The 40 CFR Part 1 51.850(a) states that no department, agency, or instrumentality of the Federal Government shall engage in, support in any way or provide financial assistance for, license to permit, or approve any activity which does not conform to an applicable state implementation plan (SIP). It is the responsibility of the Federal agency to determine whether a Federal action conforms to the applicable implementation plan, before the action is taken. If the proposed project includes any federal funding, or if the project requires any federal permits such as for streambed alteration, federal participation is not allowed unless a conformity determination has been made.
Federal actions may be exempt from conformity determinations if they do not exceed designated de minimis levels. The 40 CFR Part 51.853(b) establishes these de minimis levels for criteria pollutants. The South Coast Air Basin is a designated extreme non-attainment area for the federal 8-hour standard for ozone and non-attainment for PM10. These designations establish the de minimis air pollution emissions levels for any proposed action, which are reflected in Table 3.8-1.
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Table 3.8-1
De Minimis Levels for Criteria Pollutants Proposed Flood Wall
De Minimis Level Pollutant (tons/year) Carbon Monoxide (CO) 100 Particulate Matter (PM10) 70 Volatile Organic Compounds (VOC) 10 Nitrogen Oxides (NOx) 10
SOURCE: County of Orange; IP 06-493S
If the de minimis thresholds identified in Table 3.8-1 are not exceeded, and the proposed action does not create emissions that constitute more than ten (10) percent of the air basin’s emission budget, a formal conformity analysis is not required. Because the construction activity emissions will be limited to a small number of gasoline-powered saws and pneumatic drills, significant emissions are not anticipated and, therefore, are not expected to exceed the applicable threshold. As a result, no operational emissions will occur and no mitigation measures are required.
Project implementation includes only the construction of a flood wall to provide enhanced flood protection to properties along San Juan Creek and Trabuco Creek from approximately Ramos Street to its confluence with San Juan Creek in San Juan Capistrano and along San Juan Creek from the I-5 Freeway on the north to Stonehill Drive in Dana Point on the south. With the exception of potential maintenance, the proposed project will not result in “operational” (i.e., long-term) air emissions. As a result, only short- term (i.e., construction) impacts associated with the use of small gasoline- and pneumatic-powered equipment (e.g., saws, jackhammers, etc.) necessary to construct the flood wall. Due to the limited use of power equipment and no heavy construction activities, these short-term impacts include only construction emissions that would not exceed established thresholds, as indicated above. As previously indicated, the proposed project would also be subject to the implementation of the measures prescribed for the SSP project that was approved by the County, which include the use of best available control measures, as determined applicable, to reduce particulate emissions. In addition, the project would be subject to all applicable SCAQMD rules to ensure that emissions are minimized. Therefore, no significant air quality impacts are anticipated and no mitigation measures are required.
Even when these emissions are added to the daily construction emissions associated with the SSP Improvement project and the ACP removal and replacement project previously approved by the County, cumulative emissions would be less than significant, as identified in Table 3.8-2.
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Table 3.8-2
Cumulative Daily Construction Emissions1 Proposed Flood Wall
Activity ROG NOx CO PM10 PM2.5 ACP Removal Project 2.4 20.1 11.7 15.8 4.1 Sheetpile Project 3.91 31.07 19.48 2.17 1.96 Total 6.31 51.18 31.18 17.97 6.06 SCAQMD Thresholds 75 100 550 150 55 Difference2 68.69 48.82 518.82 132.03 48.94
1Emissions expressed in pounds per day (lbs/day). 2Difference between project-related emissions and SCAQMD Threshold.
SOURCE: County of Orange; IP 06-493S
As indicated in Table 3.8-2 and in the mitigated negative declaration (MND) and supplemental MND prepared previously for the proposed project, the construction emissions generated by the two previously approved project elements (i.e., steel sheet pile system ACP removal) are significantly below the daily significance thresholds established by the SCAQMD. Because the proposed flood wall project would not require any excavation or the use of heavy construction equipment, significant emissions are not anticipated. Pollutant emissions generated by the proposed project would not be expected to exceed the difference between the emissions generated by the approved projects and the SCAQMD thresholds for each pollutant. Therefore, even with the addition of the emissions anticipated with the proposed project, the SCAQMD significance thresholds would not be expected to be exceeded. Furthermore, because these impacts are temporary, no significant cumulative impacts are anticipated and no mitigation measures are required.
The sensitive receptors in the vicinity of the affected reaches of Trabuco Creek and San Juan Creek are the nearby single-family residential dwelling units and mobile homes. As evaluated previously in the environmental analysis prepared for the SSP project, the potential increase in construction traffic and equipment operations during the construction phase could cause a proportional increase in some odor and emissions. Approval of the proposed flood wall and resulting construction activities would not result in the creation of excessive pollutant concentrations that would adversely affect sensitive receptors. Implementation of the proposed improvements will involve only short-term activities and the use of small pieces of power equipment and hand-held equipment typical of such construction activities. However, the emission of significant concentrations of pollutants resulting from the use of construction equipment is not anticipated during the construction of the proposed flood wall. No significant impacts will occur and no mitigation measures are required beyond those prescribed by the South Coast AQMD for construction activities.
Implementation of the proposed project would not utilize either construction equipment or materials that would generate objectionable odors that could adversely affect the adjacent residential properties. As previously indicated, only gasoline- and pneumatic-powered equipment will be utilized in the construction of the proposed flood wall; no heavy equipment or diesel-powered equipment will be used. As a result, no significant or objectionable odors would be generated from the construction of the proposed project; no mitigation measures are required.
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3.9 Greenhouse Gas Emissions
Construction equipment and on-road traffic (i.e., workers traveling to and from the construction site) will generate only a limited amount of greenhouse gas (GHG) emissions possibly associated with currently observed global warming phenomenon. Because only small pieces and a limited number of construction equipment will be used to construct the flood wall, it is anticipated that the gasoline-powered saws and pneumatic drills, etc., would not emit large amounts of pollutants, including CO2e that would result in a potentially significant impact. California has adopted several initiatives to reduce GHG emissions from combustion sources. No single project or jurisdiction generates enough GHG to impact global climate. However, the cumulative impact of all combustion of fossil fuels may have global implications. As previously indicated, the proposed project would employ only small gasoline-powered and pneumatic driven equipment; no diesel engines or heavy equipment would be utilized in the construction of the flood wall. Maximum plausible CO2e emissions from on-and off-road activities associated with the project (worker vehicle trips and equipment deliveries) in any year would be very limited. Any potential increase in such project-related emissions would represent an extremely small incremental fraction of the statewide CO2 emissions. Any potential GHG emissions would be expected to fall well below the screening threshold of 3,000 MT/year. Therefore, no significant GHG impacts are anticipated and no mitigation measures are required.
As indicated in the MND prepared for the SSP project, a total of 82.4 tons/year of GHG would be generated (i.e., "worst case") based on all of the construction occurring in the same year. In addition, a minor amount of GHG would be emitted by the construction equipment that would be required to excavate the ACP from the top of the levee. However, the total GHG emissions represented less than 0.00002 percent of the statewide burden, based on 2004 statewide emissions. Because the emissions are temporary and would cease upon completion of the construction and, furthermore, are well below the 3,000 MT/year threshold, those emissions were determined to be less that significant. Finally because the construction of the fence would not utilize heavy construction equipment, the incremental increase in GHG emissions resulting from implementation of this project element would not add measurably to the total annual project-related GHG emissions.
Section 15064(h)(3) of the Guidelines provides that a “lead agency may determine that a project’s incremental contribution to a cumulative effect is not considerable if the project will comply with the requirements in a previously approved plan or mitigation program which provides specific requirements that will avoid or substantially lessen the cumulative problem.” As noted above, no such plan or program yet exists.
Section 15130 of the Guidelines sets forth the methodology by which an EIR must assess the significance of cumulative impacts. Because the MND criteria set forth in Section 15064(h)(1) and 15064(h)(3) are essentially the same as those set forth in the more detailed Section 15130, this MND utilizes that more detailed description as guidance in its evaluation of whether the Proposed Project’s potential cumulative impacts related to global climate change are significant and cumulatively considerable. Section 15130(b) states that the “following elements are necessary (emphasis added) to an adequate discussion of significant cumulative impacts:
“(1) Either:
A. A list of past, present, and probable future projects producing related or cumulative impacts, including, if necessary, those projects outside the control of the agency, or
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B. A summary of projections contained in an adopted general plan or related planning document, or in a prior environmental document which has been adopted or certified, which described or evaluated regional or area wide conditions contributing to the cumulative impact. Any such planning document shall be referenced and made available to the public at a location specified by the Lead Agency.”
Absent gross speculation, a list of past, current, and reasonably foreseeable future projects throughout the world, which potentially contribute to global warming, is not feasible to assemble. And, as discussed above, there is not yet an adopted or certified planning document, which contains a summary of projections based on known or likely worldwide projects. Although the analysis presented above cannot feasibly evaluate potential cumulative project-related global climate change impacts in the “necessary” manner currently required by CEQA, given the limited nature of the project and the temporary nature of the impacts associated with the proposed project, combined with the fact that the construction activities must comply with all applicable regulatory controls, the proposed project would not conflict with any long- term plans and/or policies currently in effect. Therefore, no significant impacts are anticipated and no mitigation measures are required.
3.10 Noise
Project implementation does not include any activities that would result in long-term (i.e., operational) noise impacts. As indicated in Section 8.d, construction noise associated with the SSP and ACP pipeline removal and replacement projects, which are currently underway and would continue during the projected construction schedule of the proposed project, may be anticipated to exceed 75 dBA (peak noise level) in the areas immediately adjacent two channels, which may adversely affect the nearby residential development in the vicinity of the channel reaches where the channel improvement projects, including the proposed flood wall, are located. With the exception of the limited use of jackhammers to cut a one-inch deep notch in the existing sheet pile cap where it has been completed along the levee, only small power equipment (e.g., saws, drills, etc.) would be employed to construct the flood wall. As a result, potential noise levels associated with the proposed flood wall project would be "masked" by the heavier construction equipment noise associated with the construction of the SSP and ACP pipeline removal activities. Therefore, project-related noise would not exceed the noise levels anticipated for the SSP project or ACP pipeline removal and relocation project that were previously approved and evaluated in IP 06-493 and IP 06-493S, respectively.
Construction noise impacts previously identified for these projects will be temporary in the vicinity of the proposed project during the construction of the proposed flood wall. Therefore, the potential noise resulting from the proposed flood wall would likely be “masked” by the higher noise levels associated with the construction of the other project elements (e.g., SSP construction and ACP removal). Because the noise levels of the smaller, less noise-intrusive equipment identified above would be less than the noise levels associated with the heavy construction equipment necessary to implement the SSP system and remove the ACP feature in the levee, the noise resulting from the erection of the flood wall would not increase the noise associated with either the SSP or the ACP pipeline removal elements analyzed and described in the MND and Supplemental MND prepared for the SSP and ACP projects, respectively. Although it is likely that jackhammers may be used in the construction of the flood wall, such noise would be limited and the noise levels generated by the jackhammers would not exceed the noise levels previously identified for related project components. Nonetheless, mitigation measures were identified to ensure that potentially significant noise impacts of the SSP Improvement project and ACP pipeline removal and replacement project are reduced to a less than significant level. The proposed flood wall
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project will also be subject to the same measures, which include limiting construction activities to normal working hours, notification of residents in the area, etc. As a result, no noise impacts beyond those identified and described in IP 06-493 for the SSP improvements and IP 05-493S for the removal of the ACP will occur and no additional mitigation measures are required.
As indicated above, jackhammers, which may be used in the construction of the flood wall on a limited basis, are the most likely potential source of vibration from project construction activities. As indicated in the prior environmental documents for the project, construction activities that would generate some vibration may be occurring as a result of the construction activities associated with the sheet pile improvement project and the ACP removal and relocation project that will be occurring concurrently along Trabuco Creek and San Juan Creek; however, any potential vibration generated by the limited use of jackhammers that may be necessary to construct the flood wall would not exceed that resulting from that associated with driving the sheet pile system along the channel walls and/or excavating the ACP pipeline. The use of machinery and equipment necessary to implement the proposed flood wall includes the use of jackhammers; however, it is anticipated that the peak ground velocity would be 0.01 inches per second (ips) at 50 feet from the source, which is less than the 0.5 ips threshold to protect more fragile structures or against cosmetic/architectural damage. No structural damage would be expected to occur at the 0.1 ips peak velocity and the vibration would be barely noticeable by humans (Giroux & Associates, February 2008). The proposed project would not result in significant ground borne vibration or noise during the construction activities that would adversely affect the nearest residential development in the vicinity of San Juan Creek and Trabuco Creek. Therefore, potential impacts will be less than significant; no mitigation measures are required.
As previously indicated, project implementation does not include elements that would generate operational noise. No increase in long-term traffic would occur and no features that would generate noise following the construction phase would occur. Therefore, no significant impacts are anticipated and no mitigation measures are required.
State law (Title 24 of the California Code of Regulations, Part 6, Section T25-28) requires that indoor noise levels in habitable rooms of multi-family dwelling units be limited to a 45 dBA CNEL. Similarly, the maximum interior noise level prescribed for both San Juan Capistrano and Dana Point is 45 dBA CNEL. Since the average attenuation factor for structures with closable windows exceeds 20 dB, a 65 dBA CNEL exterior noise exposure level is typically considered to be a desirable maximum exterior noise loading. The respective noise ordinances for the two affected cities require that maximum exterior noise levels do not exceed 65 dBA CNEL to ensure that the 45 dBA CNEL interior noise level can be achieved.
Ambient noise levels will be increased on a temporary basis only as a result of the construction activities necessary to construct the proposed flood wall; however, as indicated in the discussion presented in 8.a, the potential project-related noise would be in addition to the noise resulting from implementation of the SSP project and the ACP removal and relocation projects, also occurring along the affected reaches of Trabuco Creek and San Juan Creek. The overall construction activities, although short-term in nature, will create noise within the areas adjacent to the Trabuco Creek and San Juan Creek levees and, as previously evaluated in the environmental documents for those projects, appropriate mitigation has been incorporated into each to ensure that nearby sensitive receptors are protected from excessive noise levels. Noise associated with the proposed project would be generated by the power equipment utilized during construction.
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Temporary construction noise impacts vary markedly because the noise strength of construction equipment ranges widely as a function of the equipment used and its activity level. The use of noisy equipment could generate noise levels that range up to 75 dBA (maximum) at 50 feet from the source. However, construction noise levels will be short-term in nature and will be strictly regulated by the County’s noise ordinance, which limits the hours of construction activities. In addition to compliance with the County’s noise ordinance, appropriate sound attenuation devices will be required on all of the construction equipment utilized during the construction activities and the equipment shall be properly maintained to minimize noise exposure. Compliance with these standard procedures, which have been imposed on the SSP project and the ACP removal and relocation project occurring within the same reaches of San Juan Creek and Trabuco Creek, will ensure that noise impacts remain less than significant. No long-term noise impacts will occur as a result of project implementation of the proposed flood wall. While it is possible that the project-related noise could be “masked” by other construction activities occurring in the project vicinity, to ensure that the construction noise levels are minimized, the proposed project would be subject to the same mitigation measures prescribed for the SSP improvement project and ACP removal and relocation project, which require that the construction activities be limited to the hours of 7:00 a.m. to 6:00 p.m., Monday through Friday as prescribed by the Orange County Noise Ordinance. The City of Dana Point Noise Control Ordinance limits construction to the hours between 7:00 a.m. and 5:00 p.m. Monday through Friday, although the Director of Public Works may also approved construction on Saturdays. Construction in San Juan Capistrano is permitted between the hours of 7:00 a.m. and 6:00 p.m. on weekdays and from 8:30 a.m. to 4:30 p.m. on Saturday.
The proposed project encompasses only the construction of a flood wall along reaches of Trabuco Creek and San Juan Creek in the Cities of San Juan Capistrano and Dana Point. Aviation facilities in the County include John Wayne Airport (JWA) and Fullerton Municipal Airport (FMA). The subject property is located approximately 15 miles south of JWA and about 35 miles south of FMA; the site is not located within two miles of an airport land use plan or public airport. Because the site is not located within the limits of an airport land use plan and, further, because no development that would include sensitive receptors (e.g., residential development) is proposed, no people would be exposed to excessive noise levels associated with aviation activities at JWA or FMA. Furthermore, no private airstrips or related facilities are located in the County and no residential development or other development is proposed that would expose “sensitive receptors” or others to excessive noise and/or safety levels associated with a private airstrip. Therefore, no impacts beyond those identified in IP 06-493 (MND for the SSP project) and IP 05-493S (Supplemental MND for the ACP pipeline removal project) will result from project implementation.
3.11 Biological Resources
Trabuco Creek and San Juan Creek support a variety of vegetation in the soft channel bottom. Due to year-round stream flows, the Trabuco Creek Channel near the confluence with San Juan Creek supports a variety of vegetation that is also inhabited by a variety of avian fauna. It is possible that the existing vegetation may support such species as the least Bell’s vireo, southwestern flycatcher, and other sensitive avian species. Although no activities are proposed to occur within the channel bottom (i.e., construction equipment will be staged and operated from the levees above the channels’ reaches), construction activities resulting from construction of the flood wall, could result in temporary noise impacts that could adversely affect the least Bell’s Vireo and southwestern willow flycatcher that may occupy Trabuco Creek in the vicinity of the project site. These potential effects were previously evaluated prior to approval of the SSP and pipeline removal projects that are currently underway. The proposed project would occur concurrently with these projects along several reaches of the channels. As required in the prior analyses (IP
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06-493 and IP 06-493S), if least Bell’s vireo and/or southwestern willow flycatcher is present, it will be necessary to minimize potential impacts to those species, particularly during the breeding season. As previously indicated, with the exception of the limited use of jackhammers that may be used in the flood wall construction, noise generated by the flood wall component of the proposed project would not require the use of heavy construction equipment, which typically generate higher noise levels than smaller, hand- held equipment. Noise generated by jackhammers would not exceed noise levels previously identified for the SSP and ACP removal components of the project. The same mitigation measures would be implemented (e.g., limiting hours of construction, notification of residents, etc.) to ensure that the noise levels resulting from the limited use of jackhammers are reduced to a less than significant level as previously determined in IP 06-493 and IP 06-493S. In addition, no excavation is required and little or no dust or particulate emissions would be generated by the flood wall construction. Because the proposed flood wall construction would be occurring concurrently with the SSP project, potential noise impacts would “masked” by the higher noise levels associated with the impact equipment utilized for the SSP project. Therefore, the project is not expected to result in any habitat modifications, though there may be some temporary direct impact such as noise, as described in this paragraph. The imposition of the mitigation measures for the SSP project would be effective in avoiding significant noise impacts associated with the proposed project. Specific mitigation measures were required for the prior SSP Improvement project to ensure that such impacts either do not occur or are reduced to a less than significant level. These measures, which are identified below, would be in place during the proposed pipe removal and replacement project. As a result, no new significant impacts would occur as a result of project implementation and no additional mitigation measures beyond those previously prescribed will be required.
▪ If feasible, work will be conducted outside of the least Bell’s vireo nesting season (March 15th through August 31st).
▪ If work must occur during the nesting season, pre-construction surveys for the least Bell’s vireo and southwestern willow flycatcher shall be implemented prior to construction to determine whether either species is present within 500 feet of proposed work areas.
▪ If any nesting pairs of either species are detected during pre-construction surveys, potential indirect impacts will be minimized by providing noise attenuation such that ambient noise levels do not exceed existing levels as defined in the Noise Analysis at any active nest location.
A biological assessment was also conducted to assess the potential impacts of the proposed project on the arroyo toad, a federally designated “endangered” species and a State of California designated “species of special concern.” The study evaluated the proposed project located along specified reaches of San Juan Creek downstream of the I-5 Freeway and continuing to Stonehill Drive as Trabuco Creek from approximately Ramos Street to the confluence of that feature with San Juan Creek. The biological assessment, which was conducted by Glenn Lukos Associates (GLA), included a review of the September 2010 California Natural Diversity Data Base (CNDDB) and a biological survey along the entire length of the proposed project.
As indicated in biological assessment, the project site does not occur within currently designated critical habitat or re-proposed critical habitat for the arroyo toad, which begins immediately east of the I-5 Freeway within San Juan Creek. Furthermore, no historical or recent records of arroyo toad occurrences are document in the CNDDB for either the Dana Point or San Juan Capistrano U.S.G.S. quadrangle maps, in which the project site is located. The nearest arroyo toad occurrence to the project site
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documented in the CNDDB occurs just east of Antonio Parkway in San Juan Creek, approximately 3.2 miles upstream of the I-5 Freeway. The closest arroyo toad location to the project site available in literature occurred on June 29, 2005 in San Juan Creek, approximately 0.9 mile upstream of the I-5 freeway, just downstream of where the La Novia Bridge crosses San Juan Creek. No occurrences of arroyo toads are known west of the 2005 location.
Based on the biological assessment, the project site contains areas that exhibit characteristics consistent with low quality to marginal egg laying habitat for the arroyo toad but it lacks the necessary sandbanks, terracing, riparian vegetation, and adjacent upland habitat required for breeding, foraging, and aestivation (i.e., species dormancy similar to hibernation) habitat. Therefore, the proposed project is not expected to affect the arroyo toad or potential arroyo toad habitat due to the lack of suitable habitat and, furthermore, because the flood wall would be constructed at the top of the channel bank, along each side of San Juan and Trabuco Creeks. As a result, no new or additional impacts to the arroyo toad will occur and no mitigation measures are required.
The area of the levees of the two channels in which the work will occur is not riparian habitat or a sensitive natural community. All of the work proposed by the County will occur within the levee and maintenance road located at the top of the channel bank of Trabuco Creek and San Juan Creek. No equipment will be placed within the channel and no construction activities will occur within the channel bottom or within jurisdictional waters. As a result, project implementation will not result in any new or additional impacts or affect any naturally occurring terrestrial habitat, including wetlands, as indicated in IP 06-493 and IP 06-493S.
As indicated above, the area of direct effect does not encompass any native habitat and does not support sensitive species, although as indicated above it is possible that sensitive species may occupy habitat that exists along the affected channel reaches (e.g., least Bell’s vireo, southwestern flycatcher, etc.). Although no significant impacts associated with the proposed project would affect federally protected wetlands, the project does include some excavation at the top of the channel banks of the two affected creeks in order to construct the flood wall; however, no direct removal, filling, hydrological interruption or other impacts will occur to marshes, vernal pools, or related coastal habitat resources. Project-related impacts will be less than significant and no mitigation measures are required.
Trabuco Creek Channel and San Juan Creek Channel may serve as a wildlife corridor for both fish and small mammals traversing the area. As previously indicated, no construction activities will occur within the channel bottom and, further, all of the construction work will take place during the day and will occur along the levee; no construction is anticipated to occur at night when animal migration is more likely to occur. No changes in the hydrologic regime are anticipated (i.e., no increase in surface flows, erosion, etc., that may affect fish species). Although migration of some species may occur during the day, which may be affected by the noise and generation of dust, the impacts would not be significant because the construction activities would not directly affect the “corridor” comprising the creek bottom. As indicated in Section 11.a, above, no arroyo toads were observed and due to the low quality habitat that exists in the project area, the species is not expected to occur. Therefore, potential impacts are anticipated to be less than significant; no mitigation measures are required for the proposed project.
Project implementation will not result in the loss of any heritage trees or other significant biological resources. All of the construction activities will occur in areas that are currently paved or unvegetated at the top of the banks of the two drainage courses/flood control channels. Therefore, project implementation will not result in a potentially significant impact and no mitigation measures are required.
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As previously discussed (refer to Section 11.c), the subject site is located in the urbanized portions of San Juan Capistrano and Dana Point. The area in which the project is located is not governed by any habitat conservation plan or natural community conservation plan. Nonetheless, implementation of the proposed flood wall project are confined to the limits of the right-of-way owned by the OCFCD that encompass the affected reaches of the two creeks, which do not support any sensitive terrestrial habitats. With the exception of the potential indirect impacts to sensitive avian species that may occupy the habitat that exists in areas within the channel bottoms as previously discussed, project implementation, including the erection of the proposed flood wall, will not result in significant effects on wetlands or other sensitive habitat and/or resources; these impacts were addressed in IP 06-493 and IP 06-493S. No other impacts would occur and no mitigation measures other than those identified to address the indirect impacts identified as a result of construction dust and noise are required.
3.12 Aesthetics
Visual resources in the Cities of San Juan Capistrano and Dana Point are an important component of the quality of life identified by the General Plans in both of the affected cities. Although the City of San Juan Capistrano does not specifically define a “scenic vista,” the intent of the Open Space and Conservation Element of the General Plan is to preserve and enhance visual resources (e.g., open space, significant natural features, etc.). The Dana Point Conservation Element also acknowledges the need to preserve public views and natural vegetation as much as possible. Although not specifically identified as a scenic vista, San Juan Creek and Trabuco Creek are considered to be important open space features. In addition, the San Juan Creek Bikeway, which extends along a portion of the affected channels, is a public feature that is afforded views of the surrounding hillsides within both San Juan Capistrano and Dana Point.
As previously indicated, construction activities are planned to take place within the affected reaches of the two creeks will occur over a three-year period, resulting in the construction of a flood wall along the levees above the most southerly reach of Trabuco Creek to its confluence with San Juan Creek in the City of San Juan Capistrano, and the reach of San Juan Creek extending from the I-5 Freeway to approximately Stonehill Drive in Dana Point. As previously indicated, the flood wall is proposed to extend two to four feet above the top of the levee on each side of the affected channels and will be constructed of either split face block (approved by the City of San Juan Capistrano), slump block with sack finish, or decorative cast-in-place concrete, depending on the preference of City in which the walls are located. In addition, a 42-inch high guard cable fence is also proposed on top of the wall as a safety barrier. Although the addition of the wall would extend above the levee, it would not significantly obstruct views either from the bicycle trail or from the adjacent properties. This potential impact, which did not occur without the proposed flood wall, is less than significant, as described below.
Exhibit 2-7(refer to Chapter 2.0, Project Description) illustrates a visual simulation (i.e., Photoshop image) of a typical view of a portion of the wall that was completed for the confluence curve (i.e., the location where Trabuco Creek flows into San Juan Creek) that shows the relationship of the San Juan Creek bikeway to the adjacent creek and flood wall. As indicated in the photograph, the flood wall reflects the split face block (tan/buff in color) and the guardrail above. Construction of the flood wall would not adversely affect views from the San Juan Creek Bikeway, which is the important public vantage point in the project are. Bicyclists and others utilizing the bikeway would continue to have views of the coastal and inland hillside areas surrounding San Juan Capistrano and Dana Point. Therefore, no significant impacts are anticipated and no mitigation measures are required.
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Although the reaches of the affected Trabuco Creek and San Juan Creek are acknowledged and recognized as open space amenities within the San Juan Capistrano and Dana Point, the subject property is not characterized by any important scenic resources such as trees, rock outcroppings, or historic buildings. Moreover, the areas adjacent to the affected creeks have been developed with residential and commercial/industrial development. Further, the site is not located within the viewshed of a State scenic highway. As previously indicated, project implementation, which encompasses the construction of a 2- to 4-foot flood wall to afford the adjacent properties greater flood protection, would not adversely affect or damage the integrity of any important scenic resources. No significant impacts are anticipated and no mitigation measures are required.
As indicated above, construction of the 2- to 4-foot high flood wall above the levee along Trabuco Creek and San Juan Creek would not significant degrade the visual character or quality of the site or its surroundings. As illustrated in Exhibit 2-7, the low wall will be designed to incorporate appropriate materials (e.g., split face block or decorative cast-in-place concrete) in order to reflect the character of the area. Furthermore, the wall will be only two to four feet high (i.e., 32-inch "typical"), with a 42-inch safety high guard cable, which would not obstruct views from the bicycle trail or the adjacent public vantage points along the two creeks because it allows for visual penetration (refer to Exhibit 2-7). Therefore, as indicated above, views to the distant hillside and open space areas surrounding San Juan Capistrano and Dana Point would not be adversely affected.
Residential development located adjacent to Phases 7 & 8 along Trabuco Creek would continue to have views above the wall and through the guard cable element of the proposed improvements because the difference in elevation between the development and the top of the levee of Trabuco Creek is not significant and the guard cable component is not solid, allowing for visual penetration as illustrated in Exhibit 2-7. However, as the channel extends in a southerly direction, the elevation difference between development and the channel levee becomes greater. Although residents located on the east side of San Juan Creek adjacent to Phase 5 (refer to Exhibit 2-1) are located below the grade of the existing levee, the homes located adjacent to the channel do not have views above the levee because they are located approximately five to 8 feet below the elevation of the top of the levee. Therefore, the erection of a 32-inch wall would not significantly alter existing views from those locations. Homes located toward the interior and easterly limits of the existing development would continue to have views to the west because the effect of the wall at those distances would be diminished and views would extend well beyond the channel to the westerly hillsides. Although the visual character of the project area, when compared to the SSP and ACP removal elements previously analyzed (refer to IP 06-493 and IP 06-493S), would be changed by the erection of the proposed flood wall, existing views from the nearby properties that currently have views to the distant hillsides in the area will not be substantially altered. Distant views to the surrounding hillsides will continue to exist from important vantages (e.g., bicycle trail along the existing levee) and from development near the channel. The views to distant hillside would extend above and through the proposed flood wall and guard rail from those locations because the important vantage points along the levee and in the adjacent properties abutting the channel are located at or near the grade of the levee, which allow for lower angle views above the proposed flood wall and guard rail. For those areas adjacent to the level that are below the grade of the channel such views are currently affected or entirely blocked by the existing levee as a result of the steeper view angle from those locations. Implementation of the flood wall and guard rail would not significantly alter views from those locations. Therefore, potential visual project-related impacts would be less than significant; no mitigation measures are required.
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Project implementation would not necessitate the use of new lighting. All of the construction activities will occur during normal working hours throughout the three-year construction phasing schedule and, therefore, would not require the use of lighting during the evening hours and at night. Furthermore, lighting would not be incorporated into the project design and no long-term lighting impacts would occur. Therefore, no impacts associated with new lighting will result and no mitigation measures are required.
3.13 Cultural/Scientific Resources
The subject site encompasses specific reaches of Trabuco Creek and San Juan Creek, which have been improved to provide flood control protection in the area. Because the project site is improved as flood control facilities, the affected reaches of the Creeks do not possess any historic resources. Furthermore, project implementation does not include any excavation that would affect native soils. Construction of the flood wall would be placed directly above the SSP system. As a result, implementation of the proposed project will not result in a substantial adverse change in the significance of a historical resource as defined in Section 15064.5 of the State CEQA Guidelines. No significant impacts to historical resources are anticipated and no mitigation measures are required.
Vast areas within San Juan Capistrano, which are characterized as culturally sensitive, contain important cultural resources; however, the site has been improved as flood control facilities over many years and has been substantially altered in order to create the existing improvements. Because the levee above the two creeks is man-made, no artifacts would be expected to occur within it, especially in the upper six feet where the replacement pipeline would be located. Furthermore, no landform alteration will be required to construct the proposed flood wall. No archaeological sites are known to exist in the project area or in the immediate vicinity of the subject property. Therefore, no significant excavation is anticipated and it is unlikely that any cultural resources and materials would be encountered. Therefore, no significant impacts are anticipated and no mitigation measures are required.
Landform alteration and prior channel improvements have not resulted in impacts to any paleontological resources that may have existed prior to development. No paleontological sites are known to exist in the project area or in the immediate vicinity of the subject property. As previously indicated, project implementation would not result in any soil disturbance associated with the site. Therefore, no impacts to paleontological resources and/or related materials would occur and no mitigation measures are required.
Implementation of the proposed flood wall on the banks of affected reaches of Trabuco Creek and San Juan Creek will not adversely affect any locations where human remains are known to exist. Because no excavation will occur, none of the construction activities would be anticipated to affect human remains or other ceremonial features. No significant impacts are anticipated and no mitigation measures are required.
3.14 Recreation
The proposed flood wall project is intended to enhance flood protection along Trabuco Creek and San Juan Creek as previously identified and described. Similar to other elements of the proposed project (i.e., SSP system and ACP pipeline removal), the proposed improvements will not result in any residential development that would generate a demand for recreational facilities. Therefore, project implementation will not result in potentially significant impacts either to existing parks or recreational facilities in the Cities of San Juan Capistrano and Dana Point and no mitigation measures are required.
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The proposed project does not include recreational facilities or require the construction or expansion of existing facilities. These proposed flood control improvements do not result in demands for, or impacts to, recreational facilities. No additional impact beyond those already analyzed will occur as a result of project implementation. Therefore, no significant impacts will result and no mitigation measures are required.
3.15 Mineral Resources
The subject property encompasses a short reach of Trabuco Creek (L02) north of its confluence with San Juan Creek and San Juan Creek from the I-5 Freeway to Stonehill Drive. Neither the Cities of San Juan Capistrano and Dana Point nor the County of Orange has identified the project area as a potential mineral resource on the respective long-range plans adopted by those agencies. No significant mineral resources are known to occur on the project site or in the immediate vicinity of the project. No impacts to mineral resources were identified in the prior analyses conducted for the proposed project (refer to IP 06- 493 and IP 06-493S). Implementation of the proposed project will not result in the loss of any such resource that would be of value, either to the State or California or to the region. In addition, no improvements are currently proposed that would adversely affect locally significant and/or important mineral resources identified either by the City of San Juan Capistrano, Dana Point, or the County of Orange. Therefore, no significant impacts are anticipated and no mitigation measures are required.
3.16 Hazards and Hazardous Materials
Neither the construction activities nor the materials required for the construction of the proposed flood wall require the transport, use, or disposal of any identified hazardous materials at the subject property. In addition, no hazardous materials will be utilized on site in order to construct the proposed flood wall. Since the project activities do not involve the routine transport, use or disposal of hazardous materials, there will not be any potential risk of upset or accidents involving the release of hazardous materials into the environment. Specifically, project implementation will require the use of small equipment only (e.g., gasoline-powered saws, pneumatic drills, and/or miscellaneous hand tools) and non-toxic construction materials. With the exception of the use of gasoline-powered equipment, which is addressed in the SWPPP through the imposition of BMPs, no significant hazards to the public or the environment are anticipated; no mitigation measures are required.
The proposed construction activities, which encompass only the use of smaller hand-held power equipment that do not require the use of gasoline and/or diesel fuels or other hazardous materials, are anticipated to last approximately three years of the five-year SSP Improvement Project approved by the County. As a result, construction of the flood wall will not result in hazardous emissions or acutely hazardous materials that would pose a potential health hazard to people. The only emissions that would occur are those resulting from the use of gasoline-powered equipment (i.e., saws) needed to cut the blocks and other materials used for the creation of the proposed flood wall. However, these emissions will be composed primarily of particulates and minor pollutant emissions that do not pose a significant health risk. The project site is located in an area of the County (i.e., in the Cities of San Juan Capistrano and Dana Point) that is urbanized; however, no schools are located within one-quarter mile of the subject site. No toxic or hazardous materials are known to exist on or in the vicinity of either San Juan Creek or Trabuco Creek. Although some residential development exists in the project environs, activities associated with the flood wall project will not result in the exposure of people or schools to any existing sources of contamination that would constitute a health hazard. No new potentially significant impacts,
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when compared to the other project elements previously analyzed (i.e., SSP system and ACP pipeline removal) will occur as a result of project implementation. Potential impacts will remain less than significant; no additional mitigation measures are required.
As indicated in IP 06-493 and IP 06-493S, the subject property is not included on a list of contaminated sites. Environmental conditions on the project site and in the environs have not changed since the preparation and approval of those environmental documents. Therefore, no significant impacts will occur and no mitigation measures are required.
Aviation facilities in the County of Orange include John Wayne Airport (JWA) and Fullerton Municipal Airport (FMA). The project site is not located within two miles of these airports and, therefore, would not be within the airport land use plan adopted for those facilities. Further, no development is proposed that would be exposed to potential safety hazards associated with aviation operations at either facility. The proposed improvements are “structural” only and would not result in any permanent urban activity that would be subject to noise or other operations at JWA and FMA. Furthermore, no private airstrips or related facilities are located either in the project environs or in the County of Orange. As indicated above, the proposed improvements are “structural” only and would not result in any permanent urban activity that would be subject to noise or other operations at a private airstrip. No additional impacts beyond those previously analyzed would occur as a result of constructing the flood wall when compared to other elements of the project. Therefore, no significant impacts will occur and no mitigation measures are required.
Implementation of the proposed project will not result in any significant impacts to emergency response plans/programs. Construction of the proposed flood wall along the affected reaches of San Juan Creek and Trabuco Creek are intended to provide enhanced flood protection and, therefore, would not adversely affect the County’s existing emergency response plans or programs. As indicated in the analysis conducted for the flood control improvements in IP 06-493 (Steel Sheet Pile system) and IP 06-493S (ACP removal), no significant impact will occur and no mitigation measures are required.
The project environs is not located within a high fire hazard area. The area in which the site is located is urbanized and no wildland fire hazards exist. Further, no development is proposed that would exacerbate the existing fire hazard in the project area. Once completed, the improvements will not contribute to the potential for fires. No significant impacts will occur and no mitigation measures required.
With the exception of BMPs intended to ensure construction-related water quality impacts are addressed adequately, no other water quality facilities (e.g., detention basin, etc.) are proposed that could attract vectors or result in odors. No significant impacts are anticipated and no mitigation measures are required.
3.17 Public Facilities
The proposed project, including the flood wall, encompasses only infrastructure improvements (e.g., construction of a flood wall along specific reaches of Trabuco Creek and San Juan Creek) and does not include new development that could result in demands on emergency services and/or police and fire protection, schools and/or parks. Prior environmental analysis conducted for the project concluded that project implementation would not result in the potential for an increase in fires or in the occurrence of crime or emergency response demands in the area by the Orange County Fire Authority and Orange County Sheriff Department, respectively, which are the agencies responsible for fire protection and law
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enforcement services in the Cities of San Juan Capistrano and Dana Point. Further, project implementation would not create a need for new or expanded police protection services. The proposed project does not include new residential development and, therefore, will not result in the generation of new school age children or create a demand for parks and/or recreational facilities. Demands for governmental or other public services (e.g., libraries, public transit, postal services, etc.) are typically the result of permanent residential populations and other commercial, industrial and related development. Project implementation will require some maintenance, which will be the responsibility of OC Public Works/Flood Control; however, the maintenance requirements would not pose a significant burden on that agency. The proposed project does not include development that would create a new or greater demand for public services and facilities than previously analyzed (refer to IP 06-493 and IP 06-493S); therefore, project implementation will not result in any significant direct impacts with respect to governmental or other public services. Therefore, no significant impacts to public services will occur and no mitigation measures are required.
3.18 Utilities
The proposed project would result in the construction of a flood wall intended to improve flood protection along the affected reaches of Trabuco Creek and San Juan Creek. Project implementation, including the construction of the flood wall, does not include the development of any uses that would generate raw sewage and require collection and treatment. No new impacts will occur when compared to the other elements of the project that were analyzed previously. Therefore, no significant impacts to wastewater collection and treatment will occur and no new wastewater treatment facilities would be required to accommodate the proposed project. No significant impacts will occur and no mitigation measures are required.
No new development is proposed that would result in the demand either for domestic water supplies or water/wastewater treatment, including during the construction phase (no excavation requiring dust control is required). Project implementation will not affect existing or future water supplies and, therefore, no significant impacts will occur. Expansion of existing water and wastewater treatment facilities is not required if the project is approved and implemented. No significant impacts are anticipated and no mitigation measures are required.
Project implementation does not require or result in the development of uses that would necessitate a new storm drain infrastructure system to more efficiently accommodate the runoff associated with the site and the proposed flood wall.
Although no structures will be demolished as a result of the proposed project, project implementation does include activities associated with the construction of the flood wall, which could result in the generation of demolition/construction debris and/or refuse that may require disposal in one of the County’s sanitary landfills; however, the amount of debris would be limited and would not be expected to adversely affect landfill capacity within Orange County. The County does maintain several landfills that have adequate capacity to accommodate the construction/demolition debris and/or refuse generation by the proposed project. Where possible and feasible, the demolition and construction debris will be considered for recycling. If not recycled in accordance with the County’s Source Reduction and Recycling Element, the debris and refuse will be disposed at one of the County’s sanitary landfills. Therefore, no significant impacts and anticipated and no mitigation measures are required.
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3.19 Conclusions
The County is proposing to construct a 2- to 4-foot high flood wall along the southern extension of Trabuco Creek north of the confluence of that channel with San Juan Creek and along San Juan Creek from the I-5 Freeway to Stonehill Drive in order to increase flood protection associated with a 100-year storm even to properties located along those flood control channels in accordance with FEMA requirements. Although project implementation encompasses approximately three years of the phasing period anticipated for the Steel Sheetpile (SSP) Improvement project currently underway along those creeks, all of the potential effects associated with project implementation will be short-term in nature and would cease upon completion of the construction of the flood wall in 2015. Several of the potential project-related adverse effects (e.g., noise, air quality, biological resources) previously identified for the approved SSP and ACP removal and relocation projects would be avoided for the proposed project because a variety of mitigation measures and related standard County procedures would be implemented that would avoid or minimize the project-related impacts. As a result, these adverse effects would be less than significant (e.g., noise, etc.). Because project implementation will not necessitate grading and landform alteration, it will not result in impacts to cultural and/or scientific resources. In addition, project implementation will not substantially reduce the habitat of 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 history or prehistory. As previously indicated, potentially significant impacts have been identified and described and mitigation measures have been prescribed to ensure that the impacts are eliminated or reduced to a less than significant level.
The proposed flood wall project above Trabuco Creek and San Juan Creek must be approved by the Orange County Board of Supervisors. All of the potential impacts identified and described in the previous sections are temporary in nature and would cease upon completion of the construction activities. Implementation of this project component will not result in any significant incremental impacts beyond those caused by the existing, ongoing project. Where potential impacts have been identified, appropriate measures, including compliance with the County’s standard procedures have been identified to eliminate or reduce the potential impacts to a less than significant level. None of the impacts identified in the analysis would be cumulatively considerable because they are temporary in nature and can be mitigated. No significant operational impacts are anticipated as a result of the development of the subject property.
Approval of the proposed project will not have the potential to generate significant environmental effects which could cause adverse effects on humans, either directly (e.g., traffic and circulation, etc.) or indirectly (e.g., contribute to deficiencies in public services and/or facilities). As previously indicated, all of the impacts are short-term in nature and would cease upon completion of the improvements (i.e., approximately three years). Short-term noise impacts have been determined to be less than significant and would affect residents, either directly or indirectly. Table 3.19-1 provides a summary of the potential impacts and a comparison with the impacts associated with the proposed project. As indicated in the table, no additional impacts are anticipated with the implementation of the proposed flood wall and no new mitigation measures are required.
Addendum to the Final MND San Juan Creek/Trabuco Creek Flood Wall August 2011
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DRAFT CHAPTER 3.0 – ENVIRONMENTAL ANALYSIS
Table 3.19-1
Summary of Environmental Impacts San Juan Creek/Trabuco Creek Flood Wall
Environmental Potential Impact Proposed Flood Issue Original Project Conclusion Wall Impacts Conclusion Compared to Original Project Flood wall is Project is consistent Less than consistent with all No new or with all relevant long- Land Use and Planning Significant relevant long-range additional range plans and/or Impact plans and/or impact programs programs No important No important farmlands/agricultural farmlands/agricultural No new or Agriculture and Forestry and/or forestry No Impact and/or forestry additional Resources resources affected by resources affected impact project by flood wall Project will not result Flood wall will not in the loss of existing result in the loss of No new or Population and Housing housing and/or No Impact existing housing additional displacement of and/or displacement impact residents of residents Minor grading necessary to No grading Less than No new or implement project necessary to Geology and Soils Significant additional would expose soils to implement proposed Impact impact potential wind and flood wall water erosion No significant change No significant in surface flows change in surface associate with project Less than flows associate with No new or implementation; Hydrology and Drainage Significant flood wall, which will additional project will provide Impact provide improved impact improved flood flood protection to protection to adjacent adjacent properties properties Construction activities could result Construction of flood in some impacts to wall would not water quality; significantly increase Less than however, project types or amounts of No new or Significant Water Quality would not violate any pollutants and would additional with water quality not violate any water impact Mitigation standards or waste quality standards or discharge waste discharge requirements requirements
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DRAFT CHAPTER 3.0 – ENVIRONMENTAL ANALYSIS
Project would generate a small Flood wall number of construction would construction-related generate a small Less than trips. No uses are number of No new or Significant Transportation/Traffic proposed that construction-related additional with generate significant trips; however, impact Mitigation traffic; however, project would affect project would affect existing bicycle trail existing bicycle trail on channel levee on channel levee Flood wall Project would construction would generate short-term result in additional construction pollutant pollutant emissions; emissions; however, Less than No new or however, emissions Air Quality emissions do not Significant additional remain below exceed established Impact impact established thresholds; no long- thresholds. No long- term, operational air term, operational air quality impacts quality impacts Flood wall Project would construction would generate short-term result in additional construction CO 2 CO emissions; emissions; however, Less than 2 No new or Greenhouse Gas however, emissions emissions do not Significant additional Emissions remain below exceed established Impact impact established threshold; no long- threshold. No long- term operational term, operational air GHG impacts quality impacts Construction of flood wall would use only small, hand-held Construction construction Less than activities may result equipment. Noise No new or Significant Noise in noise levels that levels would be additional with exceed exterior noise "masked" by heavy impact Mitigation standard of 75 dBA construction equipment used for related channel improvements Indirect noise and air Indirect noise and air quality impacts from Less than quality impacts to flood wall No new or Significant Biological Resources sensitive species construction would additional with (e.g., least Bell's be less than those impact Mitigation vireo) may occur associated with related channel
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DRAFT CHAPTER 3.0 – ENVIRONMENTAL ANALYSIS
improvements; no impacts to arroyo toad Change in character of channel with the No important views addition of and/or aesthetic Less than wall/security fence; Less than Aesthetics amenities affected by Significant however, no Significant channel Impact important views Impact improvements and/or aesthetic amenities would be adversely affected No important cultural No excavation and/or scientific No new or Cultural/Scientific required; no impacts resources affected by No Impact additional Resources to cultural/scientific channel impact resources improvements No development No development proposed that would proposed that would No new or Recreation affect recreation No Impact affect recreation additional and/or require new and/or require new impact parks/recreation parks/recreation No important State, No new or regional or local Mineral Resources No Impact additional mineral resources impact affected Flood wall Project would not construction would utilize hazardous Less than not utilize hazardous No new or Hazards and Hazardous materials; project site Significant materials; project site additional Materials is not located within Impact is not located within impact an airport land use an airport land use plan plan Channel Flood wall does not No new or improvements do not Public Services No Impact require any public additional require any public services impact services Channel No new or Utilities improvements do not No Impact Flood wall does not additional require any utilities require any utilities impact
Addendum to the Final MND San Juan Creek/Trabuco Creek Flood Wall August 2011
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