Laserfiche WebLink
3.2 Excavation Shoring <br /> In order to remove the maximum volume of heavily impacted soil from the vicinity of the former <br /> UST, the proposed excavation must be shored. The proposed shoring and excavation limit is <br /> shown on Figures 4, 5, 6, 7, and 8. Approximately 50 feet of shoring will be installed along the <br /> property line between the former UST and Caltrans right-of-way. This shoring would permit <br /> excavation of the maximum amount of impacted soil without encroaching on the Caltrans right-of- <br /> way. <br /> To access the most heavily-impacted soil between the former UST and the area of ponded water <br /> C to the west, approximately 25 feet of shoring would be installed along the west side of the <br /> I' proposed excavation. For support of the shoring system, the east side of the excavation may also <br /> be shored. <br /> \Upon regulatory approval of this conceptual shoring and excavation pian, an engineered shoring <br /> Ian will be designed and certified by a state of California registered civil engineer. The shoring P g <br /> will be designed so that the maximum volume of impacted soil and groundwater can be safely <br /> removed. Temporary fencing will be used to secure the excavation when personnel are not at the <br /> site. <br /> 3.3 Excavation of impacted Soil <br /> The proposed excavation encompasses a rectangular area measuring approximately 50 feet by <br /> 25 feet by 18 feet deep. Given that groundwater is present beneath the site at approximately 14 <br /> feet bgs, the proposed excavation includes the removal of up to four feet of potentially saturated <br /> soil. The actual depth of the excavation will depend on the amount of groundwater recharge into <br /> the excavation and the competency of soils beneath the expected groundwater surface. <br /> 3.4 Excavation De-Watering <br /> To maximize the depth of excavation and to remove petroleum hydrocarbons on the groundwater <br /> surface, groundwater will be pumped from the excavation. To allow for maximum groundwater <br /> recharge and discharge, groundwater will be pumped periodically, during the excavation <br /> operation. All of the pumped groundwater will be contained in a rented water storage tank. <br /> J t� <br /> 7 <br /> ti <br />