SITE INFORMATION AND CORRESPONDENCE

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Sent By: BASELINE; 510 420 1707; Nov-9-99 17:03; Page 6113 PATHWAY ASSESSMENT There appears to be no potential contact, either directly or indirectly, between biota and chemicals of concern identified at the site in any exposure medium (air, soil, and biota). The site is entirely capped under current site conditions, devoid of vegetation, and would be largely capped under the proposed redevelopment of the site with some soils removal. A seawall is located on the north, south, and eastern portions of the Channel underneath the parking structure; cracks in the seawall would be repaired under the proposed redevelopment. Contaminants from sail would therefore not be expected to migrate to the Stockton Channel through soil movement or by surface under current or proposed conditions. Shallow groundwater at the site appears to flow easterly to southeasterly,and generally away from the Channel. The groundwater flow direction, in combination with the seawall, acts to prevent significant migration of contaminants in shallow groundwater from entering the Channel under the current site use conditions, although some groundwater seepage probably occurs. Under the proposed development where the seawall would be repaired, shallow groundwater flow into the Channel would be expected to be minimized by the presence of this seawall and the groundwater flow direction. Surface water fivm the paved structure is currently discharged to the Stockton Channel. The discharge point is located at the east end of the Channel (Bradford, 1999). However, potential contaminant contributions from the vacant site are expected to be insignificant since the site is currently capped and is not used, which reduce the potential for surface water impacts. Under the proposed redevelopment, surface water drainage from the site would be connected to the existing city storm water collection system. A conceptual site model for ecological receptors is included in Figures 8A and SB, for current and expected future conditions, with redevelopment of the site, respectively. IMPACTS TO BIOLOGICAL RECEPTORS DURING CONSTRUCTION AND PROJECT OPERATIONS Construction of the proposed project would .reduce the aquatic area by blocking 0.93 acre of the Stockton Channel. The portion of the Channel that would be isolated was identified as having limited habitat for fish species and was unlikely to support chinook salmon, Central Valley steelhead,Delta smelt,and splittail (Jones&Stokes, 1999)and other species.The loss of this habitat was therefore considered less than significant in the Draft E1R for the Stockton Weber Block Redevelopment (Jones & Stakes, 1999). During redeveloprner t of the site,mitigation measures would be implemented to mitigate potential impacts to ecological receptors during eonstmetion and the proposed project. An EIR is being prepared concurrently with this PEA that identifies potential impacts and mitigation measures. 97369stk.pra.wpd-11/9/99 28