IV. ENVIRONMENTAL IMPACT ANALYSIS H. HYDROLOGY AND WATER QUALITY

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1 IV. ENVIRONMENTAL IMPACT ANALYSIS H. HYDROLOGY AND WATER QUALITY 1. INTRODUCTION This section evaluates the Project s potential hydrology and water quality impacts based upon whether the Project would violate water quality standards or waste discharge requirements, deplete groundwater supplies, alter existing drainage patterns, exceed capacity of drainage systems, degrade water quality, or result in a loss due to flooding due to a levee or dam. A discussion of whether the Project would place housing or structures in a 100- year flood hazard area, or expose people or structures to inundation by seiche, tsunami, or mudflow is included in Section VII (Impacts Not Found to be Significant) of this Draft EIR. 2. ENVIRONMENTAL SETTING A. Project Site The Project Site consists of one full city block comprising approximately 3.55 acres bound by Vine Street to the east, De Longpre Avenue to the north, Ivar Avenue to the west, and Homewood Avenue to the south in Hollywood. The Project Site slopes gently to the south with an approximately 1.3 percent slope, and is developed with three single- story commercial buildings, surface parking areas, and lawn areas. i) Topography The Project Site slopes very gently to the south. The high point of the Project Site is located at the northwest corner, with an elevation of feet, and the low point is located at the southeast corner, with an elevation of 329 feet. Drainage across the site is by sheetflow (i.e., along the surface) to the City streets. 1 Soil Conditions Fill materials underlying the Project Site consist of silty to clayey sands, sandy silts, and sandy clays. Fill thickness is between 2.5 to six feet deep. The native soils consist primarily of silty to clayey sands, and sandy to clayey silts. Dense to very dense silty sands to sands were encountered to below a depth of 45 to 50 feet below the existing grade. The native earth materials at the Project Site consist of alluvial soils deposited by the meandering of rivers and streams, and are typical to this area of Los Angeles. 2 i Surface Water Hydrology While the Project Site is located within the Ballona Creek Watershed, there are no lakes, rivers, or streams that flow within, through, or near the Project Site. Furthermore, no ephemeral ponds exist on 1 2 Geotechnologies, Inc., Preliminary Geotechnical Engineering Investigation Proposed Mixed- Use Development N. Vine Street, N. Ivar Avenue, W. De Longpre Avenue, and W. Homewood Avenue, Hollywood, California, July 2, Ibid. Page IV.H- 1

2 City of Los Angeles March 2016 the Project Site. The nearest bodies of water to the Project Site are the Hollywood Reservoir, located approximately 1.5 miles north of the Project Site, and the Silver Lake Reservoir, located approximately 3.5 miles east of the Project Site.3 Stormwater runoff generated from the Project Site generally drains south along existing contours to the City streets and is directed towards existing storm drains. Currently, runoff from the Project Site drains via sheetflow (i.e., flows overland along the ground) in a southerly direction toward the City streets, and flows south along Cahuenga Boulevard and south along Vine Street. There is an 84- inch storm drain main line pipe in Vine Street.4 The public storm drain system discharges into Ballona Creek. Ballona Creek flows in a southwesterly direction and discharges into the Pacific Ocean at Santa Monica Bay. 1) Tsunamis, Seiches, and Flooding According to the Federal Emergency Management Agency (FEMA) Flood Insurance Rate map program, the Project Site is located in Zone X. Zone X refers to areas outside of the 0.2 percent annual chance floodplain.5 As such, the Project Site is not within a 50- or 100- year floodplain (i.e., 0.5 or 1.0 percent annual chance floodplain). Tsunamis are large ocean waves caused by the sudden water displacement that results from an underwater earthquake, landslide, or volcanic eruption. The Project Site is not located within the mapped tsunami hazard 6 boundaries. Seiches are oscillations generated in enclosed bodies of water usually as a result of earthquake related ground shaking. Hollywood Reservoir and Mulholland Dam However, the Project Site is Source: "Lake Hollywood Reservoir by clinton steeds" by Clinton Steeds from approximately 11.3 miles from the Los Angeles, USA - Lake Hollywood Reservoir, webpage: Pacific Ocean and not in proximity to Hollywood_Reservoir_by_clinton_steeds.jpg#mediaviewer/File:Lake_Hollywo any lakes such that it would be od_reservoir_by_clinton_steeds.jpg, accessed: February 4, prone to hazards of a tsunami or seiche. No major water- retaining structures are located immediately upgradient from the Project Site. However, the Project Site is within the modeled inundation boundaries of the Hollywood Reservoir. 3 As measured on screen in ZIMAS. Source: City of Los Angeles Department of City Planning, ZIMAS, website: zimas.lacity.org, accessed: December 26, City of Los Angeles Bureau of Engineering Department of Public Works, Navigate LA, website: navigatela.lacity.org/navigatela/, accessed: December 26, U.S. Department of Homeland Security Federal Emergency Management Agency National Flood Insurance Program Flood Insurance Rate Map, Los Angeles County, California, and Incorporated Areas, Map Number 06037C1605F, September 26, 2008, website: accessed: February 18, City of Los Angeles Department of City Planning, General Plan, Safety Element, Exhibit G, Inundation & Tsunami Hazard Areas in the City of Los Angeles, March Academy Square Project Page IV.H- 2 IV.H. Hydrology & Water Quality

3 iv) Groundwater The Los Angeles Water Quality Control Board region overlies 14 major regional groundwater basins, as identified by the Los Angeles Region Water Quality Control Board s Basin Plan. 7 The Project Site is located in the Hollywood Hydrological Sub- Area within the Los Angeles Coastal Plain Hydrological Area and Los Angeles- San Gabriel Valley Hydrological Unit. 8 Groundwater was encountered in borings drilled at depths of 41 and 46 feet below the ground surface. Historic high groundwater at the Project Site is reported to be 40 feet below the existing grade on the Project Site. 9 B. Regulatory Framework i) Clean Water Act The 1987 amendments to the Federal Water Pollution Control Act, commonly referred to as the Clean Water Act (CWA), added Section 402(p), which establishes a framework for regulating municipal and industrial storm water discharges under the National Pollutant Discharge Elimination System (NPDES) program. As of 1991, all municipal and industrial stormwater runoff is regulated under the NPDES system. The CWA has established 126 priority contaminants (metals and organic chemicals) and the California Ocean Plan has established effluent limitations for 21 of these pollutants. The U.S. Environment Protection Agency (EPA) is the primary Federal agency responsible for implementing the CWA. Subsequently, the EPA published final regulations that established requirements for applications for stormwater permits for specific categories of industries and construction activities. The California State Water Resources Control Board (SWCRB) and its regional water board, the Los Angeles Regional Water Quality Control Board (LARWQCB), are the primary State agencies responsible for implementing the CWA and the State s Porter- Cologne Water Quality Act within State waters. The LARWQCB is also responsible for water quality regulation through its work in preparing and adopting the California Ocean Plan. Local agencies, in addition to LARWQCB, also have responsibility for managing wastewater discharges. All are required to meet criteria set forth in their NPDES permits, to monitor their discharges, and to submit monthly reports to the LARWQCB and the EPA. In addition to infrastructure deficiencies, the increasing volume of stormwater runoff has become the major source of pollutants discharging into the Los Angeles River Los Angeles Region Water Quality Control Board, Basin Plan, Page 1-20, Figure 1-9, Regional Groundwater Basins. Los Angeles Region Water Quality Control Board, Basin Plan, Page 1-6, and Page 1-7 Figure 1-2, Hydrologic Units. Geotechnologies, Inc., Preliminary Geotechnical Engineering Investigation Proposed Mixed- Use Development N. Vine Street, N. Ivar Avenue, W. De Longpre Avenue, and W. Homewood Avenue, Hollywood, California, July 2, Page IV.H- 3

4 General Construction Activity Stormwater Permit In 2003, the California State Water Resources Control board (SWRCB) adopted the General Construction Activity Stormwater Permit (General Permit), which is required for all storm water discharges associated with construction activity where clearing, grading, and excavation results in a land disturbance of one or more acres. The most recent General Permit is effective as of July 1, In order to be covered under the General Permit, the project Applicant must submit a Notice of Intent (NOI), a Storm Water Pollution Prevention Plan (SWPPP), and other documents required by the General Permit, and mail the appropriate permit fee to the SWRCB. The General Permit requires all dischargers where construction activity disturbs one acre or more to: Develop and implement a SWPPP which specifies Best Management Practices (BMPs), as further discussed below, that will prevent all construction pollutants from contacting storm water with the intent of keeping all products of erosion from moving off site into receiving waters; Eliminate or reduce non- storm water discharges to storm sewer systems and other Waters of the United States; and Perform inspections of all BMPs. 10 The General Permit authorizes the discharge of stormwater associated with construction activity from construction sites. However, it prohibits the discharge of materials other than stormwater and all discharges which contain hazardous substances in excess of reportable quantities, established at 40 Code of Federal Regulations or CFR 302.4, unless a separate NPDES permit has been issued to regulate those discharges. In addition, the General Permit incorporates discharge prohibitions contained in water quality control plans, as implemented by the nine Regional Water Boards. 11 The General Permit requires development and implementation of a SWPPP, emphasizing BMPs, which are defined as schedules of activities, prohibitions of practices, maintenance procedures, and other management practices to prevent or reduce the pollution of waters of the United States. The SWPPP has two major objectives: to help identify the sources of sediment and other pollutants that affect the quality of stormwater discharges; and to describe and ensure the implementation of BMPs to reduce or eliminate sediment and other pollutants in storm water as well as non- storm water discharges. The SWPPP shall include BMPs which address source control and, if necessary, shall also include BMPs which address pollutant control. Furthermore, the General Permit requires that a project enrolled in more than a three- month construction period to submit information and annually certify that the site is in compliance with the National Pollutant Discharge Elimination System (NPDES) General Permit For Storm Water Discharges Associated With Construction Activity (General Permit) Water Quality Order DWQ, Fact Sheet, page 1, website: accessed December 26, Ibid, page 4. Page IV.H- 4

5 requirements of the General Permit. The General Permit requires that key personnel (e.g., SWPPP preparers, inspectors, etc.) have specific training or certifications to ensure their level of knowledge and skills are adequate to ensure their ability to design and evaluate project specifications that will comply with General Permit requirements. 12 Erosion control and drainage devices are required to be provided in accordance with the General Construction Activity Stormwater Permit and SWPPP as well as the MS4 Permit (see below). i Los Angeles County MS4 Permit The Los Angeles Regional Water Quality Control Board Order No. R , NPDES No. CAS00400, effective December 28, 2012, Waste Discharge Requirements for Municipal Separate Storm Sewer System (MS4) Discharges within the Coastal Watersheds of Los Angeles County (the MS4 Permit ), controls the quality of runoff entering municipal storm drains in the County. The MS4 Permit is intended to ensure that combinations of site planning, source control and treatment control practices are implemented to protect the quality of receiving waters. To do so, the MS4 Permit requires that new development employ BMPs designed to control pollutants in stormwater runoff, details specific sizing criteria for BMPs, and specifies flow control requirements. These BMPs include structural practices, source control and treatment techniques and systems, and site design planning principles addressing water quality. Section VI.D.8, of the MS4 Permit, Development Construction Program, requires Permittees (including the City of Los Angeles) to enforce implementation of Best Management Practices (BMPs), including, but not limited to, approval of an Erosion and Sediment Control Plan (ESCP) for all construction activities within their jurisdiction. Applicants and construction contractors are required to implement BMPs that would meet or exceed local, State, and Federal mandated guidelines for storm water treatment to control erosion and to protect the quality of surface water runoff during the construction period. BMPs utilized could include, without limitation, the following: disposing of waste in accordance with all applicable laws and regulations; cleaning up leaks, drips, and spills immediately; conducting street sweeping during construction activities; limiting the amount of soil exposed at any given time; covering trucks; keeping construction equipment in good working order; and installing sediment filters during construction activities. Under existing regulations, for construction sites over one acre in size, the contractor would file a NOI with the State Water Resources Control Board and prepare a SWPPP before the start of any construction activity. With respect to runoff water quality during operation, Section VI.D.7 of the MS4 Permit, Planning and Land Development Program, is applicable to, among others, development projects equal to one acre or 12 Ibid, page 6. Page IV.H- 5

6 greater of disturbed area and adding more than 10,000 square feet of impervious surface. This program requires, among other things, that projects retain on site the runoff volume from (a) the 0.75 inch, 24- hour rain event or (b) the 85th percentile, 24- hour rain event, as determined from the Los Angeles County 85th percentile precipitation isohyetal map, whichever is greater. Structural BMPs, also referred to as treatment control BMPs, involve physical treatment of the runoff, usually through structural means. Site design or planning management BMPs are used to minimize runoff from new development and to discourage development in environmentally sensitive areas that are critical to maintaining water quality. Among other things, the MS4 Permit requires the co- permittees to prepare a Stormwater Quality Management Plan (SQMP) specifying the BMPs that will be implemented to reduce the discharge of pollutants in stormwater to the maximum extent possible (MEP). The various components of the SQMP, taken together, are expected to reduce pollutants in stormwater and urban runoff to the MEP. The emphasis of the SQMP is pollution prevention through education, public outreach, planning, and implementation of source control BMPs first, followed by structural and treatment control BMPs. Erosion control and drainage devices are required to be provided in accordance with the MS4 Permit in addition to the General Construction Activity Stormwater Permit and SWPPP. Moreover, runoff controls are required to be provided in accordance with the MS4 Permit, in addition to the SUSMP and LID Ordinance (see below). iv) Standard Urban Stormwater Mitigation Plan The Standard Urban Stormwater Mitigation Plan (SUSMP), approved by the LARWQCB for the Los Angeles Region on March 8, 2000, was developed as part of the municipal stormwater program to address stormwater 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 project. Additional BMPs may be required by ordinance or code adopted by the Permittee 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 stormwater 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 inches 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. 13 Runoff controls are required to be provided in accordance with SUSMP, in addition to the LID Ordinance (see below) MS4 Permit. The Project Applicant, or successor in interest is required to prepare and execute a covenant and agreement (Planning Department General Form CP- 6770) satisfactory to the Department of City Planning binding the owners to post construction maintenance on the structural and operational BMPs in accordance with the SUSMP and/or per manufacturer s instructions. 13 Standard Urban Storm Water Mitigation Plan for Los Angeles County and Cities in Los Angeles County, March 8, 2000, page 10. A copy of the SUSMP can be downloaded from the following website: accessed December 30, Page IV.H- 6

7 v) City of Los Angeles Low Impact Development (LID) Ordinance The provisions of the Low Impact Development (LID) Ordinance No. 181,899, adopted by the City Council on September 28, 2011, are designed to mitigate the impacts of increases in runoff and stormwater pollution as close to the source as possible. LID comprises a set of site design approaches and BMPs that promote the use of natural systems for infiltration, evapotranspiration and use of stormwater. The LID Ordinance requires projects to incorporate LID standards and practices to encourage the beneficial use of rainwater and urban runoff, reduce stormwater runoff, promote rainwater harvesting, and provide increased groundwater recharge. In this regard, the City has established review procedures to be implemented by the Department of City Planning, Department of Building and Safety, and Department of Public Works that parallel the review of the SUSMP discussed above. Runoff controls are required to be provided in accordance with the LID Ordinance, in addition to the SUSMP and MS4 Permit. vi) Los Angeles Building Code and Municipal Code Earthwork activities associated with the grading and export of soil are required to occur in accordance with City requirements, as specified in the Los Angeles Building Code and California Building Code and through the grading plan review and approval process, including a haul route approval as specified in the LAMC. 3. ENVIRONMENTAL IMPACTS A. Thresholds of Significance i) Appendix G to the State CEQA Guidelines In accordance with guidance provided in Appendix G to the State CEQA Guidelines, the Project could have a 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. Page IV.H- 7

8 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 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. j) Result in inundation by seiche, tsunami, or mudflow. As discussed in Section VII (Impacts Not Found to be Significant) and in the Initial Study (see Appendix A to this Draft EIR), the Project would have no impact with respect to Impacts (g), (h), and (j) listed above. No further analysis of these topics is required. City of Los Angeles CEQA Thresholds Guide As set forth in the L.A. CEQA Thresholds Guide, a project would normally have a significant impact if it would: k) 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. l) Substantially reduce or increase the amount of surface water in a water body. m) 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. n) Discharges associated with the project would create pollution, contamination or nuisance as defined in Section of the California Water Code (CWC) (see definitions below) or that cause regulatory standards to be violated, as defined in the applicable NPDES stormwater permit or Water Quality Control Plan for the receiving water body. o) Change potable water levels sufficiently to: i) Reduce the ability of a water utility to use the groundwater basin for public water supplies, conjunctive use purposes, storage of imported water, summer/winter peaking, or to respond to emergencies and drought; i iv) Reduce yields of adjacent wells or well fields (public or private); or Adversely change the rate or direction of flow of groundwater; or Result in demonstrable and sustained reduction of groundwater recharge capacity. p) Affect the rate or change the direction of movement of existing contaminants. q) Expand the area affected by contaminants. r) Result in an increased level of groundwater contamination (including that from direct percolation, injection or salt water intrusion). s) Cause regulatory water quality standards at an existing production well to be violated, as defined in the California Code of Regulations (CCR), Title 22, Division 4, and Chapter 15 and in the Safe Drinking Water Act. Page IV.H- 8

9 B. Project Impacts Threshold (a): The Project could have a significant impact if it were to violate any water quality standards or waste discharge requirements. Impact (a): With compliance with the MS4 Permit, SWPPP, SUSMP, and the City s LID Ordinance, construction and operational water quality impacts would be less than significant. i) Demolition and Construction Typically, runoff picks up pollutants as it flows over the ground or paved areas and carries these pollutants into the storm drain system or directly into natural drainages. There are three general sources of short- term construction- related stormwater pollution associated with the Project: (1) the handling, storage, and disposal of construction materials containing pollutants; (2) the maintenance and operation of construction equipment, and (3) earth moving activities which, when not controlled, may generate soil erosion. As discussed in Section IV.G (Hazards and Hazardous Materials), elevated concentrations of tetrachloroethene (PCE) above regulatory standards were discovered in soil and soil gas in areas on the Project Site reportedly used to store solvents used for film cleaning. During demolition, the mitigation measures listed in Section IV.G of this EIR would be implemented, which would reduce the impact with respect to hazardous materials to a less- than- significant level. With respect to water quality, the implementation of the mitigation measures in listed in Section IV.G of this EIR would ensure that this potential source of stormwater pollution would be reduced to a less- than- significant level. During construction, the Project Site would contain a variety of construction materials such as adhesives, cleaning agents, landscaping, plumbing, painting, heat/cooling, masonry materials, floor and wall coverings, and demolition debris. Spills of construction materials can be a source of stormwater pollution and/or soil contamination. All hazardous materials are to be stored, labeled and used in accordance with the U.S. Occupational Safety and Health Administration (OSHA) regulations. These regulations for routine handling and storing of hazardous materials effectively control the potential stormwater pollution caused by these materials. Earth moving activities would be controlled via shoring. Soil erosion is the process by which soil particles are removed from the land surface, by wind, water and/or gravity. Soil particles removed by stormwater runoff can have negative impacts on downstream conditions. Grading activities can greatly increase erosion processes. Two general strategies are typically required to prevent construction silt from entering drainage courses. First, the amount of exposed soil is typically limited and erosion control procedures are implemented for those areas that must be exposed. Common mitigation measures for controlling fugitive dust emissions, such as covering truck loads and street sweeping, are also effective in controlling stormwater quality. Second, the construction area would be secured to control off- site migration of pollutants. Erosion control devices, including temporary diversion dikes/berms, drainage swales, and siltation basins, are typically required around construction areas to insure that sediment is trapped and properly removed. These measures would be implemented through compliance with the requirements of the General Construction Activity Stormwater Permit, including implementation of a SWPPP, and the MS4 Permit. The Project SWPPP will identify potential pollutant sources that may affect the quality of discharge associated with construction activity, identify non- storm water discharges, and provide design features to effectively prohibit the entry of pollutants into the public storm drain system Page IV.H- 9

10 during construction. When properly designed and implemented, these BMPs would ensure that short- term construction- related water quality impacts would be less than significant. Operation There are three single- story commercial buildings, surface parking areas, and lawn areas currently on the Project Site. Under existing conditions, runoff from the Project Site may contain urban pollutants, such as automotive fluids- oils, and heavy metals, that are discharged into the storm drainage system. The Project would be required to comply with the MS4 Permit, SUSMP, and City of Los Angeles LID Ordinance to retain and treat storm water and prevent additional flows to City s Storm Water Drainage System. Per the latest LID guidelines, new construction developments must treat stormwater through infiltration, capture and reuse, or biofiltration. The Project proposes to use biofiltration planter boxes on site to treat stormwater as well as to capture stormwater for its reuse on site in landscaping. With compliance with the MS4 Permit, SUSMP, and LID Ordinance, the operational water quality impacts would be less than significant. Threshold (b): The Project could have a significant impact if it were to 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). Impact (b): The construction and operational impacts to groundwater supplies and groundwater recharge would be less than significant. i) Construction Groundwater was encountered in borings drilled at depths of 41 and 46 feet below the ground surface. Historic high groundwater at the Project Site is reported to be 40 feet below the existing grade. 14 Groundwater conditions in the future may vary substantially as a result of seasonal variations of rainfall. The Project would be constructed over a four- level subterranean parking structure and excavation is expected to be approximately 45 to 50 feet below existing grade. Therefore, the excavation of the subterranean parking structure could encounter the groundwater table. As such, a dewatering plan would be employed during excavation activities. This plan would consist of a series of deep wells at the perimeter of and within the Project footprint, and could include some surface drainage to sumps. The deep wells would draw down the water table by pumping the groundwater from the aquifer and discharging it into the local storm drain system. Once the water is drawn down, construction could be completed in moist but not saturated soils. The buildings would be designed to be compatible with the water table without requiring any operational pumping (i.e., designed for hydrostatic pressure as recommended by the geotechnical engineer for the Project). 15 Since the Project would be designed for hydrostatic pressure (i.e., designed to withstand the pressure exerted by the groundwater), following construction of the buildings, the pumps and water discharge would be discontinued. As such, the Geotechnologies, Inc., Preliminary Geotechnical Engineering Investigation Proposed Mixed- Use Development N. Vine Street, N. Ivar Avenue, W. De Longpre Avenue, and W. Homewood Avenue, Hollywood, California, July 2, Ibid., page 11. Page IV.H- 10

11 Project would not result in significant impacts related to the availability of groundwater and would not result in the alteration of groundwater flows. Therefore, construction impacts to groundwater would be less than significant. Operation Direct additions or withdrawals of groundwater are not proposed by the Project. As part of its design, the Project would capture stormwater in cisterns, filter the water through biofilters, 16 then discharge the water into storm drains within 72 hours of capture. While the Project would increase the amount of impermeable surfaces at the Project Site, no adverse change in groundwater recharge capacity is expected with Project operation because such change would be comparatively negligible from the existing condition to the Project condition due to the urbanized setting of the Project Site and limited recharge potential of the site in its existing condition. Accordingly, operational impacts to groundwater would be less than significant. Threshold (c): The Project could have a significant impact if it were to 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. Impact (c): The construction and operational impacts to drainage patterns with respect to the potential for erosion or siltation would be less than significant. i) Construction No river or stream traverses the Project Site, nor would the Project alter an existing off- site river or stream. During Project construction, a temporary alteration of the existing on- site drainage pattern may occur. However, these changes would not result in substantial erosion or siltation due to stringent controls imposed under the General Construction Activity Stormwater Permit, including implementation of a SWPPP, and the MS4 Permit. With implementation of the required BMPs, drainage impacts during construction would be less than significant. Operation If not properly designed and constructed, the Project could increase the potential that surface water runoff could be redirected and cause flooding. However, the Project is unlikely to alter the drainage pattern in a manner that would result in substantial erosion or siltation because the Project Site slopes gently to the south and would be required to comply with the requirements of the SUSMP, MS4 permit and LID Ordinance, which would reduce the volume of runoff from the Project Site after the Project is constructed. In addition, the Project would not modify the surrounding streets with respect to the manner in which they convey storm runoff to the City storm drain system. Similar to existing conditions, runoff from the Project would drain via sheetflow in a southerly direction toward the city streets. Therefore, the operational impact on drainage patterns with respect to the potential for erosion or siltation would be less than significant. 16 Biofiltration is a pollution control technique using living material to capture and biologically degrade process pollutants. Page IV.H- 11

12 Threshold (d): The Project could have a significant impact if it were to 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. Impact (d): The construction and operational impacts to drainage patterns with respect to the potential for flooding would be less than significant. i) Construction As discussed under Impact (c), during Project construction, a temporary alteration of the existing on- site drainage pattern may occur from the demolition of existing structures and land cover, and the excavation to construct the subterranean parking structure. The on- site soils have a moderate potential to be expansive (i.e., to increase in volume from absorption of water and to shrink when dried out). 17 However, these changes would not result in a substantial increase in the rate or amount of surface runoff that could result in flooding due to stringent controls imposed under the General Construction Activity Stormwater Permit, including implementation of a SWPPP, and the MS4 Permit. With implementation of the required BMPs, drainage impacts during construction would be less than significant. Operation As discussed under Impact (c), the Project would be required to comply with the requirements of the SUSMP, MS4 permit and LID Ordinance, which would reduce the volume of runoff from the Project Site after the Project is constructed. The Project would not modify the surrounding streets with respect to the manner in which they convey storm runoff to the City storm drain system, and would have no effect on regional facilities. While the Project would increase the amount of impermeable surfaces at the Project Site, similar to existing conditions, runoff from the Project would drain via sheetflow in a southerly direction toward the City streets; however, the stormwater would be better managed by a cohesive drainage treatment and conveyance design throughout the Project Site, which is currently not present. Additionally, the Project would capture stormwater for on- site landscaping. The proposed landscaping would include biofiltration to treat the stormwater prior to discharge into the City s existing storm water drainage system. Therefore, the operational impact on drainage patterns with respect to the potential for flooding would be less than significant. Threshold (e): The Project could have a significant impact if it were to 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. Impact (e): The construction and operation of the Project would not introduce substantial sources of polluted runoff. Therefore, the impact would be less than significant. The Project would not substantially increase the amount of surface runoff from the Project Site. The Project would prepare a SWPPP to prevent runoff and water quality impacts during construction as well 17 Geotechnologies, Inc., Preliminary Geotechnical Engineering Investigation Proposed Mixed- Use Development N. Vine Street, N. Ivar Avenue, W. De Longpre Avenue, and W. Homewood Avenue, Hollywood, California, July 2, 2014, page 13. Page IV.H- 12

13 as comply with the SUSMP and MS4 Permit. Moreover, the Project would comply with the LID Ordinance. Therefore, stormwater runoff from the Project Site is not expected to exceed the capacity of the existing or planned stormwater drainage systems. However, should the City determine improvements to the stormwater drainage system are necessary during the permit review process, the Applicant would be responsible for the improvements, and such improvements would be conducted as part of the Project either on- site of off- site within the right- of- way. The stormwater drainage infrastructure construction activities would be temporary and of short duration, and would not result in significant environmental impacts. Furthermore, as the Project would manage, capture, and treat runoff, as required by regulatory compliance, implementation of the Project would represent an improvement in water quality from the existing conditions because runoff currently sheetflows along various land cover untreated to the drainage system. Thus, a less- than- significant impact would occur with respect to surface runoff volume during operation. As discussed under Impact (a), the construction and operation of the Project would not introduce substantial sources of polluted runoff which could exceed the capacity of the existing systems. Therefore, this impact would be less than significant. Threshold (f): The Project could have a significant impact if it were to otherwise substantially degrade water quality. Impact (f): With implementation of regulatory requirements, water quality impacts associated with the construction and operation of the Project would be less than significant. As discussed under Impact (a), with implementation of regulatory requirements, water quality impacts associated with the construction and operation of the Project would be less than significant. Additionally, the Project proposes a mix of residential and commercial land uses, which does not represent the type of use that would otherwise degrade water quality (e.g., an industrial land use could adversely affect water quality). No other water quality impacts would occur. Threshold (g): The Project could have a significant impact if it were to 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. As discussed in Section VII (Impacts Not Found to be Significant) and in the Initial Study (see Appendix A to this Draft EIR), the Project would have no impact with respect to Threshold (g) listed above. No further analysis of this topic is required. Threshold (h): The Project could have a significant impact if it were to place within 100- year flood hazard area structures which would impede or redirect flood flows. As discussed in Section VII (Impacts Not Found to be Significant) and in the Initial Study (see Appendix A to this Draft EIR), the Project would have no impact with respect to Threshold (h) listed above. No further analysis of this topic is required. Threshold (i): The Project could have a significant impact if it were to 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. Impact (i): Impacts related to potential inundation from the failure of a levee or dam would be less than significant. Page IV.H- 13

14 The Project Site is within the inundation boundaries of the Hollywood Reservoir. 18,19 However, according to the Federal Emergency Management Agency (FEMA) Flood Insurance Rate map program, the Project Site is located in Zone X (unshaded). Zone X (unshaded) refers to areas outside of the flood zone. 20 Furthermore, the Hollywood Reservoir located behind the Mulholland Dam, was built in 1924 and reinforced following the failure of the similarly designed St. Francis Dam in The Hollywood Reservoir is no longer used as a Los Angeles Department of Water and Power (LADWP) water storage facility, having been replaced as such by two 30- million gallon underground storage tanks installed in the Hollywood Hills in The Hollywood Reservoir is utilized today primarily for recreational uses and is maintained by the LADWP, which monitors the status of the dam and areas surrounding the lake. Based on the operating history of the dam and the continuous scrutiny by LADWP, the potential for failure of the dam that could result in inundation of the downstream area, is extremely low. As such, impacts related to potential inundation from the failure of a levee or dam would be less than significant. Threshold (j): The Project could have a significant impact if it were to violate any water quality standards or waste discharge requirements. As discussed in Section VII (Impacts Not Found to be Significant) and in the Initial Study (see Appendix A to this Draft EIR), the Project would have no impact with respect to Threshold (j) listed above. No further analysis of this topic is required. Threshold (k): The Project would normally have a significant impact if it would 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. Impact (k): There would be no impact during construction or operation of the Project due to flooding during a projected 50- year storm event. The Project site is in Flood Zone X and, therefore, outside of the 50- year annual chance floodplain. 22 As such, the Project would not be impacted by flooding which could harm people or damage property or sensitive biological resources. As such, there would be no impact during construction or operation. Threshold (l): The Project would normally have a significant impact if it would substantially reduce or increase the amount of surface water in a water body Geotechnologies, Inc., Preliminary Geotechnical Engineering Investigation Proposed Mixed- Use Development N. Vine Street, N. Ivar Avenue, W. De Longpre Avenue, and W. Homewood Avenue, Hollywood, California, July 2, City of Los Angeles Department of City Planning, General Plan, Safety Element, Exhibit G, Inundation & Tsunami Hazard Areas in the City of Los Angeles, March City of Los Angeles Bureau of Engineering Department of Public Works, Navigate LA, website: navigatela.lacity.org/navigatela/, accessed: December 26, The failure of the St. Francis Dam was subsequently attributed primarily to the underlying geology at that site, rather than the design of the dam. Outland, Charles F. Man- Made Disaster: The Story of St. Francis Dam. A.H. Clark Company, Water and Power Associates, Mulholland Dam and Hollywood Reservoir, website: accessed: July 7, Zone X are areas determined to be outside of the 0.2 percent annual chance floodplain. A 50- year storm event is in a 0.5 percent annual chance floodplain. Page IV.H- 14

15 Impact (l): The Project would not reduce or increase the amount of surface water in a water body and there would be no impact. There are no lakes, rivers, or streams that flow within, through, or near the Project Site. No ephemeral ponds exist on the Project Site. As discussed under Impacts (c) and (d), the Project would not substantially increase the amount of surface runoff from the Project Site. Therefore, the Project would not reduce or increase the amount of surface water in a water body and there would be no impact. Threshold (m): The Project would normally have a significant impact if it would 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. Impact (m): The impacts during construction and operation would be less than significant. The impact during construction and operation for this threshold would be comparable to that which is described under Impacts (c), (d), and (e) above. As indicated therein, impacts to drainage patterns and runoff would be less than significant. Threshold (n): The Project would normally have a significant impact if discharges associated with the project would create pollution, contamination or nuisance as defined in Section of the California Water Code (CWC) or that cause regulatory standards to be violated, as defined in the applicable NPDES stormwater permit or Water Quality Control Plan for the receiving water body. Impact (n): With compliance with the MS4 Permit, SWPPP, SUSMP, and the City s LID Ordinance, construction and operational water quality impacts would be less than significant. The impact during construction and operation for this threshold would be comparable to that which is described under Impact (a) above. As indicated therein, impacts to water quality would be less than significant with compliance with the MS4 Permit, SWPPP, SUSMP, and the City s LID Ordinance. Threshold (o): The Project would normally have a significant impact if it would change potable water levels sufficiently to: i) Reduce the ability of a water utility to use the groundwater basin for public water supplies, conjunctive use purposes, storage of imported water, summer/winter peaking, or to respond to emergencies and drought; Reduce yields of adjacent wells or well fields (public or private); i Adversely change the rate or direction of flow of groundwater; or iv) Result in demonstrable and sustained reduction of groundwater recharge capacity. Impact (o): Impacts during construction and operation would be less than significant. The impact during construction and operation for this threshold would be comparable to that which is described under Impact (b) above. As indicated therein, the construction of the Project could encounter the groundwater table and, thus, a dewatering plan would be employed during excavation activities that would include pumps to dewater the site. However, as recommended by the geotechnical engineer, the Project would be designed for hydrostatic pressure and, as a result, permanent pumping during operation of the Project would not be necessary. Moreover, the Project does not propose to extract groundwater nor do such activities currently occur at the Project Site. While the Project would increase Page IV.H- 15

16 the amount of impermeable surfaces at the Project Site, no adverse change in groundwater recharge is expected. Construction and operational impacts would be less than significant. Threshold (p): The Project would normally have a significant impact if it would affect the rate or change the direction of movement of existing contaminants. Impact (p): With implementation of regulatory requirements, water quality impacts associated with the construction and operation of the Project would be less than significant. The impact during construction and operation for this threshold would be comparable to that which is described under Impacts (a), (e), and (f) above. As indicated therein, impacts to water quality would be less than significant with compliance with the MS4 Permit, SWPPP, SUSMP, and the City s LID Ordinance. Moreover, the Project would not introduce substantial sources of polluted runoff. Threshold (q): The Project would normally have a significant impact if it would expand the area affected by contaminants. Impact (q): With implementation of regulatory requirements, water quality impacts associated with the construction and operation of the Project would be less than significant. i) Construction The Project would adhere to the requirements of a General Permit, and construction associated with the Project would be subject to the requirements of the MS4 Permit, which controls the quality of runoff entering municipal storm drains in the County. Accordingly, a SWPPP would be developed in compliance with SWRCB requirements and implemented during Project construction, which would outline BMPs and other measures to minimize the discharge of pollutants in stormwater runoff. The SWPPP would also be subject to the City s Best Management Practices Handbook, Part A Construction Activities. Therefore, with compliance with regulatory requirements, construction- related impacts would be less than significant with respect to expanding the area affected by contaminants. Operation Operation of the Project would entail the preparation and implementation of a Project- specific SUSMP meeting the requirements of the County- wide SUSMP adopted by LARWQCB, and implementation of BMPs designed to address runoff and pollutants. These BMPs would address water quality of the stormwater runoff through management, capture, and treatment of runoff from the Project Site. Furthermore, implementation of the Project would represent an improvement in water quality from the existing condition as runoff currently sheet flows along the various land cover untreated and into the drainage system. Therefore, with compliance with regulatory requirements, operation- related impacts would be less than significant with respect to expanding the area affected by contaminants. Threshold (r): The Project would normally have a significant impact if it would result in an increased level of groundwater contamination (including that from direct percolation, injection or salt- water intrusion). Impact (r): With implementation of regulatory requirements, water quality impacts associated with the construction and operation of the Project would be less than significant. Page IV.H- 16