Draft EA - San Diego International Airport

SAN DIEGO INTERNATIONAL AIRPORT – PROPOSED RUNWAY 9 DISPLACED THRESHOLD
In addition, rainfall runoff as a potential transport mechanism for pollutants, these same pollutants have the
potential to be transported by “dry weather runoff/dry weather flows”. Any flow in the stormwater
conveyance system during periods of dry weather is considered a dry weather flow. Dry weather flows can
originate from over irrigation of landscaped areas, air conditioning condensation, high groundwater or
groundwater sump pumps, and accidental, improper, or illegal discharges to the stormwater conveyance
system. Common examples of the latter are accidental spills of jet fuel or lavatory waste, or improper vehicle
or pavement washing activities, or illegally disposed used motor oil or antifreeze.
In light of the potential for pollutants to be transported to San Diego Bay through the stormwater conveyance
system, SDIA is subject to both the State Industrial General Stormwater Permit (National Pollutant Discharge
Elimination System (NPDES) Permit No. CAS000001) and the San Diego Municipal Stormwater Permit (NPDES
Permit No. CAS0108758). In response to these permit requirements, the SDCRAA has developed and
implemented a stormwater management program to prevent or reduce the discharge of polluted runoff from
SDIA during rain events and during instances of dry weather flow.
Due to poor quality, groundwater underlying SDIA and the former NTC is not used for drinking, irrigation, or
industrial supply purposes. No existing or potential beneficial uses for groundwater are designated in these
areas. According to the San Diego Basin Plan, groundwater within this Hydrologic Area has been exempted
by the San Diego Regional Water Quality Control Board (RWQCB) from the municipal use designation under
the terms and conditions of State Board Resolution No. 88-63, “Sources of Drinking Water Policy.”
Groundwater testing at the former NTC indicates that metals and minerals did not exceed total threshold
concentration limits; however, concentrations of chromium, copper, lead, nickel, and zinc exceeded San Diego
RWQCB standards for protection of marine resources in San Diego Bay. Groundwater exceeding these
standards, removed as part of construction site dewatering activities at SDIA, is subject to NPDES permitting
and would require either discharge into the sanitary sewer system or treatment before discharge into the
Bay. 30
3.5.3 WETLANDS
The U.S. Army Corps of Engineers’ (USACE) Wetland Delineation Manual defines wetland areas that have
positive indicators for hydrophytic vegetation, wetland hydrology, and hydric soils as “areas that are
inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that
under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil
conditions.” The USACE typically takes jurisdiction over wetlands only when they lie within or adjacent to
navigable waters, or tributaries of such waters where those tributaries bear an ordinary high water mark. An
ordinary high water mark is defined as “that line on the shore established by the fluctuations of water and
indicated by physical characteristics such as a clear, natural line impressed on the bank, shelving, changes in
soil character, destruction of terrestrial vegetation, presence of litter or debris, or other appropriate means
that consider the characteristics of the surrounding areas.”
30
Redevelopment Agency of the City of San Diego, November 1999.
Draft EA
Affected Environment
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