SU0014093 - Laserfiche WebLink

Home Browse Search

Projects that disturb one acre of ground or more are required to obtain a Construction General Permit from the SWRCB. Conditions of the Construction General Permit would require preparation of a Storm Water Pollution Prevention Plan (SWPPP) by a Qualified SWPPP Developer; the SWPPP would include implementation of Best Management Practices to avoid or minimize adverse water quality impacts from erosion and sedimentation. Best Management Practices fall within the categories of Temporary Soil Stabilization, Temporary Sediment Control, Wind Erosion Control, Tracking Control, Non -Storm Water Management, and Waste Management and Materials Pollution Control. It is anticipated that project development would require a Construction General Permit. Implementation of the conditions of this permit would reduce project impacts related to soil erosion to a level that would be less than significant. c) Unstable Soils. The project site is a mostly developed area on essentially flat land. There is no evidence of the instability of soils on the project site. Subsidence is the sinking of a large area of ground surface in which the material is displaced vertically downward, with little or no horizontal movement. The main cause of subsidence in valley areas is the withdrawal of groundwater from aquifers, while within the Sacramento -San Joaquin Delta region, oxidation of peat is the main cause. Subsidence is primarily an issue within the Delta region, and the project site is not within the Delta (San Joaquin County 2016a). The geotechnical report stated the underlying undisturbed soils encountered are considered adequate for support of moderately loaded structures with post -tensioned foundations (CTE Cal 2021). Geologic hazards at the site are primarily limited to those caused by near -surface expansive soils, which are discussed below. Project impacts related to unstable soils would be less than significant. d) Expansive Soils. As noted above, Jacktone clay has a high expansiveness potential. The geotechnical report stated that geologic hazards at the site are primarily limited to those caused by near -surface expansive soils susceptible to volume change upon wetting or drying. If not treated, these soils could exhibit post construction volume change upon drying and wetting and cause damage to foundations, structures, and flatwork (CTE Cal 2021). Treatment options to mitigate this hazard are presented in the geotechnical report. The options would be required to be implemented under Mitigation Measure GEO-1. Implementation of this measure would ensure that project impacts related to expansive soils would be less than significant. Level of Significance: Potentially significant Mitigation Measures: Implementation of Mitigation Measure GEO-1. Significance After Miti ag tion: Less than significant Pock Lane Public Review Draft IS/MND 3-33 May 2022