IV. ENVIRONMENTAL IMPACT ANALYSIS G. HYDROLOGY/WATER QUALITY

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1 IV. ENVIRONMENTAL IMPACT ANALYSIS G. HYDROLOGY/WATER QUALITY ENVIRONMENTAL SETTING The project site is located in the Wilshire community of the City of Los Angeles and is bound by S. Wetherly Drive to the west, W. 3 rd Street to the north, S. Almont Drive to the east, and an alley to the south (see Figures II-1 and II-2 in Section II., Project Description). The project site consists of a rectangular parcel and totals approximately acres. The topography of the project site is generally flat. Based on information shown on the published United States Geological Survey (USGS) topographic map for the area, the average elevation within the project site is approximately 194 feet above the mean sea level (msl) with area drainage generally directed to the south. 1 Surface Water Hydrology The project site is located within the Ballona Creek Watershed. The Ballona Creek Watershed is a drainage area of approximately 130 square miles that includes most of the City of Los Angeles west of downtown, the cities of Beverly Hills, Culver City, and West Hollywood and portions of Santa Monica and Inglewood. Ballona Creek is the dominant hydrologic feature in the watershed and drains surface waters to the Pacific Ocean. There are no lakes, rivers, or streams that flow within, through or near the project site. The nearest surface water is a stream located on the Los Angeles Country Club approximately 1.83 miles west of the project site. 2 The project site is not located in a 100 or 500 year floodplain. 3 However, the project site is within a potential inundation area for the Hollywood reservoir. 4 Stormwater runoff generated at the project site generally drains southerly. Stormwater runoff flows onto the surrounding roadways and enters the existing drainage system Geotechnical Investigation Report, Proposed Mid-Rise Multi-Family Residential Development Project Nicholson S. Wetherly Drive and S. Almont Drive, Beverly Hills Area of Los Angeles, California, prepared by Petra Geotechnical, Inc., December 22, Included as Appendix F. Phase I Environmental Site Assessment, 321 & 323 South Almont Drive, Los Angeles, California 90048, prepared by AEI Consultants, February 6, Included as Appendix G. City of Los Angeles Department of City Planning, Zone Information and Map Access System, website: accessed May 1, City of Los Angeles, Safety Element of the Los Angeles City General Plan, Exhibit G, Inundation & Tsunami Hazard Areas, March Page IV.G-1

2 Groundwater The project site is located within the Santa Monica Subbasin. The Santa Monica Subbasin underlies the northwestern part of the Coastal Plain of Los Angeles Groundwater Basin. It is bounded by impermeable rocks of the Santa Monica Mountains on the north and by the Ballona escarpment on the south. The subbasin extends from the Pacific Ocean on the west to the Inglewood fault on the east. Replenishment of groundwater in the Santa Monica Basin is mainly by percolation of precipitation and surface runoff onto the subbasin from the Santa Monica Mountains. Groundwater was encountered at a depth of 53 feet below existing grade during the geotechnical investigation performed at the project site. 5 As indicated by the California Geologic Survey Seismic Hazard Evaluation Report (CGS, 1998), the project site may be subject to historic high groundwater levels of up to approximately 10 feet below existing grade. Fluctuations in groundwater levels may occur due to variations in rainfall, regional climate, and in response to landscape irrigation. The direction of groundwater flow beneath the project site is inferred to be to the southeast. 6 Regulatory Framework Clean Water Act In 1972, the Federal Water Pollution Control Act (also referred to as the Clean Water Act [CWA]) was amended to provide that the discharge of pollutants to waters of the United States from any point source is unlawful unless the discharge is in compliance with a National Pollutant Discharge Elimination System (NPDES) permit. The 1987 amendments to the CWA added Section 402(p) which establishes a framework for regulating municipal and industrial storm water discharges under the NPDES Program. In 1990, the U.S. Environmental Protection Agency (USEPA) published final regulations that establish storm water permit application requirements for specified categories of industries. The regulations provide that discharges of storm water to waters of the United States from construction projects that encompass five or more acres of soil disturbance are effectively prohibited unless the discharge is in compliance with an NPDES Permit. Regulations (Phase II Rule) that became final on December 8, 1999 expand the existing NPDES program to address storm water discharges from construction sites that disturb land equal to or greater than one acre and less than five acres (small construction activity). 5 6 Geotechnical Investigation Report, Proposed Mid-Rise Multi-Family Residential Development Project Nicholson S. Wetherly Drive and S. Almont Drive, Beverly Hills Area of Los Angeles, California, prepared by Petra Geotechnical, Inc., December 22, Included as Appendix F. Phase I Environmental Site Assessment, 321 & 323 South Almont Drive, Los Angeles, California 90048, prepared by AEI Consultants, February 6, Included as Appendix G. Page IV.G-2

3 In California, these permits are issued through the State Water Resources Control Board (SWRCB) and the nine Regional Water Quality Control Boards (RWQCBs). The project site is within the jurisdiction of the Los Angeles Regional Water Quality Control Board (LARWQCB). While federal regulations allow two permitting options for storm water discharges (individual permits and General Permits), the California State Water Resources Control Board (SWRCB) has elected to adopt only one Statewide General Permit. Dischargers are required to submit a Notice of Intent (NOI) to obtain coverage under this General Permit. This General Permit requires all dischargers where construction activity disturbs one acre or more to: 1. Develop and implement a Storm Water Pollution Prevention Plan (SWPPP) which specifies Best Management Practices (BMPs) that will prevent all construction pollutants from contacting storm water and with the intent of keeping all products of erosion from moving off site into receiving waters. 2. Eliminate or reduce non-storm water discharges to storm sewer systems and other waters of the nation. 3. Perform inspections of all Best Management Practices (BMPs). Standard Urban Storm Water Mitigation Plan The Standard Urban Stormwater Mitigation Plan (SUSMP), approved by the California Regional Water Quality Control Board for the Los Angeles Region March 8, 2000, was developed as part of the municipal stormwater program to address storm water pollution from new development and redevelopment by the private sector. The SUSMP contains a list of the minimum required BMPs that must be used for a designated project. Additional BMPs may be required by ordinance or code and applied generally or on a case by case basis. Developers must incorporate appropriate SUSMP requirements into their project plans. The SUSMP is designed to eliminate 85 percent of the pollutants in storm runoff from new developments via requirements for implementation of a first flush cleansing program. The requirements of the program are such that the first 0.75 inch of rainfall runoff from a 24-hour storm is to be intercepted from drainage areas where new development is occurring and be cleansed, filtered or retained until pollutants are removed. 7 7 Standard Urban Storm Water Mitigation Plan for Los Angeles County and Cities in Los Angeles County, March 8, 2000, page 10. Page IV.G-3

4 ENVIRONMENTAL IMPACTS Thresholds of Significance Appendix G of the State CEQA Guidelines In accordance with guidance provided in Appendix G of the State CEQA Guidelines, the Proposed Project could have a potentially significant impact if it were to: (a) Violate any water quality standards or waste discharge requirements; (b) Substantially deplete groundwater supplies or interfere substantially with groundwater recharge such that there would be a net deficit in aquifer volume or a lowering of the local groundwater table level (e.g., the production rate of pre-existing nearby wells would drop to a level which would not support existing land uses or planned uses for which permits have been granted); (c) Substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a stream or river, in a manner, which would result in substantial erosion or siltation on- or off-site; (d) Substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a stream or river, or substantially increase the rate or amount of surface runoff in a manner which would result in flooding on- or off-site; (e) Create or contribute runoff water which would exceed the capacity of existing or planned stormwater drainage systems or provide substantial additional sources of polluted runoff; (f) Otherwise substantially degrade water quality; (g) Place housing within a 100-year flood hazard area as mapped on a federal Flood Hazard Boundary or Flood Insurance Rate Map or other flood hazard delineation map; (h) Place within a 100-year flood hazard area structures which would impede or redirect flood flows; (i) Expose people or structures to a significant risk of loss, injury or death involving flooding, including flooding as a result of the failure of a levee or dam; or (j) Expose people or structures to a significant risk of loss, injury or death involving inundation by seiche, tsunami, or mudflow. Page IV.G-4

5 City of Los Angeles CEQA Thresholds Guide Furthermore, as set forth in the City of Los Angeles L.A. CEQA Thresholds Guide, a proposed project would normally have a significant impact on surface water hydrology if it would: (a) Cause flooding during the projected 50-year developed storm event which would have the potential to harm people or damage property or sensitive biological resources; (b) Substantially reduce or increase the amount of surface water in a water body; or (c) Result in a permanent, adverse change to the movement of surface water sufficient to produce a substantial change in the current or direction of water flow. Project Impacts Water Quality Construction Because the Proposed Project would include excavation and grading, the project site would require a General Construction Activity Storm Water Permit from the SWRCB prior to the start of construction. The Construction General Permit requires the development and implementation of a SWPPP. According to the SWRCB, the SWPPP should identify which structural and nonstructural BMPs will be implemented, such as sandbag barriers, temporary desilting basins near inlets, gravel driveways, dust controls, employee training, and general good housekeeping practices. In addition, the Proposed Project would be required to obtain a grading permit from the Department of Building and Safety. With implementation of the applicable grading and building permit requirements and the application of BMPs, the Proposed Project would not violate any water quality standards or waste discharge requirements. Therefore, impacts on water quality from construction activities would be less than significant. Operation If not properly designed and constructed, the Proposed Project could increase the rate of urban pollutant introduction into storm water system. In order to prevent these potential impacts, the project will be designed in compliance with: (1) Section 402(p) of the Federal Water Pollution Control Act, or Clean Water Act (CWA); (2) Order No of the Regional Water Quality Control Board, Los Angeles Region, which regulates the issuance of waste discharge requirements to Los Angeles County; (3) the County of Los Angeles SUSMP, and (4) the City of Los Angeles Municipal Code. The SUSMP identifies the types and sizes of private development projects that are subject to its requirements. Due to the amount of square footage and the nature of the land use proposed by the project, it would be subject to the requirements of the SUSMP. In compliance with the SUSMP requirements, the Proposed Project would provide for the treatment/filtration of on-site storm water runoff before it enters the public storm water conveyance system, in order to minimize the introduction of pollutants of concern. Page IV.G-5

6 As required by the SUSMP, this system must remove 85 percent of such first flush storm water pollutants such as hydrocarbon compounds (i.e., automotive oils, lubricants and other fluids) deposited, as a matter of course, along the proposed driveway. Applicable BMPs will also be selected from those approved sources identified in the SUSMP. Other aspects of the SUSMP with which the Proposed Project must comply include provisions for the proper design of outdoor material and trash storage areas. As noted above, the Proposed Project would provide structural or treatment control BMPs designed to control storm water runoff contamination. While some infiltration through landscape areas will occur, the Proposed Project will primarily rely on the implementation of treatment control BMPs to control storm water runoff contamination. As required by the SUSMP, detailed plans for the Proposed Project s compliance with the SUSMP will be submitted to the City as part of the development plan approval process prior to issuance of building and grading permits. With compliance with the SUSMP requirements, the project s operational impacts on stormwater quality will be less than significant. Groundwater Groundwater was encountered at a depth of 53 feet below grade during site investigations on December 7, As discussed above, the site may be subject to historic high groundwater levels of up to approximately 10 feet below ground surface (bgs). The development of the Proposed Project includes excavation to roughly 35 feet bgs for subterranean parking. In general, groundwater is not anticipated to be encountered during the proposed construction. Nonetheless, to minimize the chance of encountering groundwater during construction, the Geotechnical Report recommends the construction of the subterranean levels be conducted in mid to late summer. Compliance with the recommendations of the Geotechnical Report is included in Mitigation Measure G-1. The Proposed Project would develop the project site with greater amounts of impervious surfaces than under existing site conditions. The project site would be excavated and subterranean parking created beneath the entire project site; this would result in more impervious surface area compared to existing conditions. However, the project site is not an important area of groundwater recharge as groundwater replenishment in the project area is mainly via precipitation and surface runoff from the Santa Monica Mountains. Water used in the construction and operation of the Proposed Project would be conveyed via existing potable water infrastructure and, as such, the project would not contribute directly to lowering the water table through the use of wells. Therefore, construction and operation of the Proposed Project would not result in significant impacts related to groundwater. 8 Geotechnical Investigation Report, Proposed Mid-Rise Multi-Family Residential Development Project Nicholson S. Wetherly Drive and S. Almont Drive, Beverly Hills Area of Los Angeles, California, prepared by Petra Geotechnical, Inc., December 22, Included as Appendix F. Page IV.G-6

7 Drainage The project site currently drains into an existing storm drain located in the surrounding roadways. Development of the Proposed Project would not substantially change the existing drainage patterns on the project site. The runoff from the Proposed Project would continue to be directed towards and discharged into the existing public storm drain system, in a manner consistent with applicable NPDES storm water permits. The City of Los Angeles Department of Public Works will review and approve the proposed drainage system as part of the project plan check to ensure that runoff is properly conveyed through the property and discharged to avoid flooding. Additionally, the Proposed Project would implement the recommendations with respect to drainage contained in the Geotechnical Report, also required by Mitigation Measure F-1. Therefore, construction and operation of the Proposed Project would not result in significant impacts related to site drainage. Flooding The project site is within a potential inundation area for the Hollywood reservoir. 9 However, the failure of a levee or dam is considered to be a remote possibility that would likely only occur during extremely severe seismic shaking conditions. Flooding from other sources is not expected, thus the minimal risk of flooding from potential dam or levee failure would not be exacerbated by the development of the Proposed Project. In addition, large portions of the City of Los Angeles are also within potential inundation areas, as such, risk to the project site would not be greater than in many other areas of the City. Therefore, the potential impact associated with flooding due to the failure of a levee or dam would be less than significant. CUMULATIVE IMPACTS Development of the Proposed Project in conjunction with the 53 related projects listed in Section III., Environmental Setting, would impact storm drainage and water quality in the area. The Proposed Project is located in an urbanized area where most of the surrounding properties are already developed. The proposed storm drainage system serving this area has been designed to accommodate runoff from the existing built environment. New construction does not generally lead to substantial additional runoff, since new developments would also be required to control the amount of stormwater runoff coming from their respective sites. Thus, the Proposed Project would not contribute to a significant cumulative impact in the event that any off-site areas served by local storm drains were to increase peak flows to the system and no cumulatively considerable impacts to water runoff and water quality would occur. 9 City of Los Angeles, Safety Element of the Los Angeles City General Plan, Exhibit G, Inundation & Tsunami Hazard Areas, March Page IV.G-7

8 MITIGATION MEASURES G-1. The Proposed Project shall be designed and constructed in accordance with the recommendations provided in the Geotechnical Report, which shall be approved by the Department of Building and Safety prior to issuance of building and grading permits. LEVEL OF SIGNIFICANCE AFTER MITIGATION With implementation of the mitigation measure listed above, project impacts with regard to hydrology and water quality would be less than significant. Page IV.G-8