Environmental Impact Statement - Sonoma Land Trust

California Department of Fish and Game
U.S. Fish and Wildlife Service
Section 3.3. Water Quality
Conclusion: Less than Significant.
Impact WQ-8: Degradation of Water Quality due to
Contaminated Soils in Proposed Tidal Basin
Proposed Project
As part of the Project, soil would be excavated from the Black Point Sports Club
and used to construct a portion of the new flood control levee along the SMART
rail line. As discussed above, the soils from the Sports Club contain contaminants
derived from lead shot and clay targets, primarily lead and PAHs (Northgate
2006). If these soils are not remediated, cContaminants from these soils would
therefore have the potential to leach into the tidal wetland and disperse to San
Pablo Bay. A Corrective Action Plan for the Black Point Sports Club site was
developed for SLT by Northgate Environmental Management in December 2006
and approved in November 2008. The Corrective Action Plan details
contaminant levels and proposed remediation activities for the site. The preferred
remediation measure proposed in the plan is excavation of 12,000 CY of
contaminated soils to be subsequently used (encapsulated) in construction of the
new flood control levee. After excavation is completed, soil samples would be
taken to confirm that the proposed cleanup criteria have been achieved; if not,
additional soil would be removed and the remaining soil retested until the criteria
met (Northgate 2006). Additionally, a long-term soil management plan would be
developed to control access to the interred soil and inform future landowners of
the presence and location of the soil.
Upon completion of the proposed restoration, tidal waters would come into direct
contact with the new flood control levee. If contaminants from levee fill were to
disperse into the water column, impacts on water quality would be potentially
significant. Because contaminated soils would be used to construct the erosion
control/habitat slopes levee core and subsequently covered with at least 3 feet of
clean cover materials, the likelihood of contaminated soils coming into contact
with surface waters would be minimal. Implementation of the Corrective Action
Plan would ensure that all contaminated soils from the Sports Club site are
appropriately excavated and sequestered during levee construction. Therefore,
this impact is considered less than significant, and no mitigation is required.
Conclusion: Less than Significant.
Full-Tidal Alternative
Similar to the Project, contaminated soils would be used to construct the new
levee core and would be covered with at least 3 feet of clean cover materials.
Therefore, the likelihood of contaminated soils coming into contact with surface
waters would be minimal. Implementation of the Corrective Action Plan would
ensure that all contaminated soils from the Sports Club site are appropriately
Sears Point Wetland and Watershed Restoration
Project Final Environmental Impact
Report/Environmental Impact Statement
3.3-25
April 2012