SFPUC 2001 Alameda Watershed Management Plan

III. ENVIRONMENTAL SETTING AND IMPACTSC. GEOLOGY AND SOILSChanges to Gravel Mining OperationsGravel mining is proposed north of I-680, and gravel extraction operations would continue southof I-680. Under the Management Plan, mining south of I-680 would continue under one of twoseparate options. The following discussion applies to both continuing mining operations andproposed options.Mining operations could result in erosion of surrounding soils by wind, water, or excavation.Expansion of mining south of I-680 would require amendments to existing permits south of I-680but would not significantly alter topography, because the Management Plan only proposes toincrease the depth of existing mining pits or to expand the mining footprint to conform toboundaries of the leased acreage. The increase in mining depths and footprint would not be likelyto impact geology and soils beyond levels previously analyzed and mitigated in previousenvironmental documentation. It may be reasonably assumed that Alameda County would applyconditions of approval to the permit modifications consistent with those of SMP-24, SMP-30, andapplied to more recent permit permits such as SMP-32 that mitigate significant effects of mining.Mining to a greater depth should not have a significant geotechnical impact if designconsiderations relating to pit side slopes are followed, as required by Alameda County inconditions of approval for all three SMPs mentioned above. These conditions of approval alsoinclude requirements for erosion control plans for mining activities. Amendment of the existingpermits would be subject to project-level environmental review by Alameda County.• The impacts to geology and soils from proposed mining activities north of I-680 were analyzed inthe Mission Valley Rock Company Surface Mining Permit and Reclamation Plan SMP-32 EIR.The potential impacts identified would be mitigated through implementation of pertinentmitigation measures that were adopted as conditions of approval of SMP-32 by Alameda County.Actions proposed in the Management Plan would take place substantially in accordance withlimits and mitigations set forth in the conditions of approval for Alameda County’s SMP-32.These include requirements for grading, erosion control, and slope maintenance as mentionedabove. The Management Plan incorporates SMP-32 conditions of approval and proposesmodification in the timing and sequencing of mining and mining reclamation. Thesemodifications may require amendment of the existing permit but would not bring about any newgeology and soils impacts beyond those disclosed in the EIR prepared for SMP-32. Amendmentof the existing permit, if required, would be subject to additional environmental review byAlameda County.REFERENCES – Geology and Soils_________________________Except where indicated, references are on file at the San Francisco Planning Department.Alameda County Planning Department, Mission Rock Company SMP-24 Initial Study, 1985.(Available at Alameda County Community Development Agency Planning Department,Hayward, California)NOP 96.223E: Alameda Watershed Management Plan III.C-13 ESA / 930385January 2001