FIELD DOCUMENTS - Laserfiche WebLink

Home Browse Search

4.2 Soil Remediation The soil and groundwater remediation program was observed by Treadwell&Rollo on 19 and 20 April 2005. The 2005 Workplan proposed excavation of contaminated soil and groundwater around sample location CPT-EXC-BT-19. The-excavation was 25 feet wide by 10 feet long by 25 feet deep as shown on Figure 2. The excavation extended to 25 feet deep,which is approximately 6.0 feet below the 19-foot deep groundwater table in order to remove contaminated groundwater and contaminated saturated soil. The proposed excavation represented approximately 230 cubic yards(bench yards)or up to 370 tons of soil,,,and=it�was-estimated-that up to-12;000 gallons of contaminated-groundwater:ma be_.=, .removed, Excavation below 25 feet was not attempted due to limitation at the shoring available. Since the excavation perimeter was shored, it was not proposed to collect confirmation samples from the sidewalls. 4.3 Shoring and Soil Excavation On 13 April through 19 April 2005 the perimeter of the excavation was shored with interlocking metal sheet piles. The shored excavation dimensions were 25 feet long, 10 feet wide and 25 feet deep. Previous sampling had indicated that the top 15 feet of soil was not contaminated; therefore this soil was stockpiled separately from.the bottom 10 feet of the excavation. Approximately-150 cubic-yards ofsoil-excavated=deeper.than=l-5-feet:bgs=were-removed:and;:� , .stockpiled for characterization?Mr.Jeff Wong of the SJCEHD was periodically on site to observe the excavation. 4.4 Groundwater Extraction,Treatment and Disposal Approximately-7,50&gallons of groundwater were pumped from the excavation-and stored in an 18;000 gallon-Baker- to analysis. The analytical results met the discharge requirements-of the City.of-Stockton.Municipal-"Utilities Department(SMUD),and SMUD ,issued a'25 May 2005 discharge permit'for the-water:(Appendix A). On 26 May 2005 the 25971024.DGD 6 7 June 2005