Laserfiche WebLink
1 <br /> Manteca Unified School District <br /> 2901 E. Louise Ave., Lathrop, California <br /> Remedial Excavation Report <br /> 1.0 Project Identification <br /> ' This assessment has been conducted to define the Iateral and vertical extent of gasoline and/or <br /> diesel contamination in the soil and groundwater at the District Office and Transportation <br /> Facility at Lathrop, California <br /> 2.0 Project History <br /> Manteca Unified School District has been operatmg at the subject location since 1972 On <br /> May 26,1993, Manteca Unified School District contracted with SEMCO, a licensed hazardous <br /> substances removal and remediation contractor, to remove their underground fuel tanks On <br /> ' June 15, 1993, SEMCO removed one(1) 12,000 gallon gasoline tank (designated as Tank # <br /> 2) and one (1) 12,000 gallon diesel fuel tank (designated as Tank # 3) A 1,000 gallon tank <br /> (known as Tank#1) had been previously removed Soil samples taken at the time of Tanks 2 <br /> & 3 removal showed the presence of contamination to a depth of 19 feet below surface An <br /> Excavation Work Plan was submitted by SEMCO -.o the San Joaquin County Environmental <br /> ' Health Department on June 22, 1993, and amended by an Addendum Number One letter <br /> dated June 30, 1993 The Work Plan designated WHF Environmental Consultants, Inc , to <br /> oversee all activities and coordinate with San Joaquin County Public Health Serv'ces, <br /> ' Environmental Health Department <br /> ' 3.0 Scope and Summary of Present Work <br /> On July 7, 1993, SEMCO excavated the former underground tank faemhty at Manteca Unified <br /> 1 School District WHF screened soil samples with a portable PID and logged the lnthology of <br /> the exposed walls (Appendix A), using the Unified Soil Classification System (USCS) Highly <br /> contaminated soils were encountered both above and below the water table of 16 feet in the <br /> original tank removal excavation The amended Work Plan called for vertical excavation to <br /> approximately-23 feet <br /> ' Two trenches were excavated from the northwest corner of the pit and screened with the PID <br /> to delineate the lateral extent of contammatmon (Figure 3) These trenches were limited to 16 <br /> feet in depth because of sand caving and sloughing The estimated excavation size at that time <br /> was beyond the school district's budget, and additional exploration trenching was terminated <br /> before PID readings decreased to zero One area in the northwest corner was deepened to 23 <br /> feet and dnsclosea groundwater contamination <br /> 1 <br />