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these bio-filtration basins would be typical of runoff collected from a commercial development and would not
<br /> contain substantial quantities of pollutants that could not be appropriately treated by the proposed BMPs.
<br /> In summary, Project grading and construction would be completed in accordance with an NPDES-mandated
<br /> SWPPP, which would include standard BMPs to reduce potential off-site water quality impacts related to erosion
<br /> and incidental spills of petroleum products and hazardous substances from equipment. Surface water runoff
<br /> during project operations would be managed through a mixture of strategies that would be designed to remove
<br /> pollutants from on-site runoff prior to discharge into the storm drain system to the maximum extent practicable, as
<br /> required by the SWQCCP. Therefore, impacts associated with water quality standards, waste discharge
<br /> requirements, and surface water or groundwater quality would be less than significant, and this issue will not be
<br /> further evaluated in the Draft EIR.
<br /> b) Potentially Significant Impact. Domestic, irrigation, and fire suppression water would be sourced on the Project
<br /> site through the installation of two on-site water wells, and the Project would include a 500,000-gallon
<br /> aboveground water storage tank that would be reserved for fire suppression uses only. Further analysis is
<br /> required to determine whether the Project could substantially decrease groundwater supplies or interfere
<br /> substantially with groundwater recharge such that the project may impede sustainable groundwater management
<br /> of the basin. This topic will be analyzed further in the Draft EIR.
<br /> c-i) Less-than-Significant Impact. Under the existing conditions, the Project site is undeveloped and contains
<br /> various elevated areas and depressions. The Project would involve grading activities that would bring the project
<br /> site to a flat grade and the construction of new paved surfaces, warehouse buildings, and landscape areas. The
<br /> Project would also include a new engineered stormwater drainage system that would feature structural BMPS
<br /> such as retention facilities to treat and manage stormwater flows. While the Project's future drainage conditions
<br /> would be designed to mimic the existing on-site drainage conditions to the maximum extent practicable,
<br /> construction activities would inevitably result in changes to the internal drainage patterns of the site. However, the
<br /> Project's future storm drain system will be designed to conform with applicable federal, state, and local
<br /> requirements related to drainage, hydrology, and water quality, including the County's SWQCCP.
<br /> Per the requirements of the County's SWQCCP, project plans will be required to demonstrate the capacity to
<br /> capture and treat all on-site stormwater generated by two consecutive 10-year, 24-hour storm events, thereby
<br /> reducing the potential for the Project to result in stormwater flows off site that could result in erosion on or off site.
<br /> In addition, the Project's structural BMPs would be designed such that any potential sediments collected on site
<br /> would be captured in retention facilities so that they would not be conveyed to downstream waters and result in
<br /> siltation. As such, alteration of the on-site drainage pattern would be conducted in a manner consistent with all
<br /> applicable standards related to the collection and treatment of stormwater, such that it would not result in
<br /> substantial erosion or siltation on or off site. Therefore, impacts associated with altering the existing drainage
<br /> pattern of the Project site and erosion or siltation would be less than significant, and this issue will not be further
<br /> evaluated in the Draft EIR.
<br /> c-ii)Less-than-Significant Impact.As discussed above, the project would inevitably result in changes to the internal
<br /> drainage patters of the project site. However, the Project's future storm drain system will be designed to conform
<br /> with applicable federal, state, and local requirements related to drainage, hydrology, and water quality, including
<br /> the County's SWQCCP. As such, alteration of the on-site drainage pattern would be conducted in a manner
<br /> consistent with all applicable standards related to the collection and treatment of stormwater.
<br /> In addition, according to the Flood Insurance Rate Map No. 06077CO73OF (FEMA 2020)for the Project area, the
<br /> Project site is located within Zone X, which is defined by the Federal Emergency Management Agency as an area
<br /> located outside of the 100-year and 500-year flood plains. Therefore, impacts associated with altering the existing
<br /> drainage pattern of the Project site and flooding would be less than significant, and this issue will not be further
<br /> evaluated in the Draft EIR.
<br /> c-iii) Less-than-Significant Impact.As previously addressed, the Project would inevitably alter the drainage
<br /> patters of the project site; however, the Project would include a new engineered stormwater drainage system that
<br /> would be designed to conform with applicable federal, state, and local requirements related to drainage,
<br /> hydrology, and water quality, including the SWQCCP. Alteration of the on-site drainage pattern would be
<br /> conducted in a manner consistent with all applicable standards related to the collection and treatment of
<br /> stormwater. Therefore, impacts associated with altering the existing drainage pattern of the Project site and
<br /> stormwater would be less than significant, and this issue will not be further evaluated in the Draft EIR.
<br /> c-iv) Less-than-Significant Impact.As discussed above, the project would inevitably result in changes to the
<br /> internal drainage patterns of the project site. However, the Project's future storm drain system will be designed to
<br /> conform with applicable federal, state, and local requirements related to drainage, hydrology, and water quality,
<br /> including the County's SWQCCP. As such, alteration of the on-site drainage pattern would be conducted in a
<br /> Enter oroiect#s. —Initial Study 24
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