ARCHIVED REPORTS_DRYWELL CLOSURE AND INVESTIGATION

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r May 30, 2014 1 DRYWELL CLOSURE AND INVESTIGATION ' NEIL 0. ANDERSON &ASSOCIATES 902 INDUSTRIAL WAY LODI, CALIFORNIA r rEXECUTIVE SUMMARY This report describes the closure and investigation of non-permitted waste water disposal system at Neil 0. Anderson & Associate's (NOA) Office in Lodi, San Joaquin County, California. NOA's Lodi Office contains an on-site Concrete Cure Room with drainage to two (2) exterior ' drywells. The San Joaquin County Environmental Health Department (EHD)_ipspected this waste water disposal system on March 6, 2014 and deemed it unsuitableA�'t9kpproaches and methodologies for Class V well closure and investigation activities to gather data to evaluate the ' case for closure or determine the need for further remedial action are detailed in the work plan completed by NOA on March 18, 2104, revised March 20, 2014, and approved by the EHD on March 26, 2014. The wells were destructed by overdrilling. Soil and groundwater samples were collected beneath the vertical extent of each drywell. Soil sampling was performed on five-foot intervals beneath the wells until groundwater was encountered. Constituents of Potential Concern (COPCs) were not identified in any soil samples analyzed. Groundwater contained elevated levels of petroleum hydrocarbons. The absence of contaminants in soil above ' groundwater indicates that groundwater contamination is from a different source. ? 1.0 INTRODUCTION ' Neil 0. Anderson & Associates (NOA) is required to close and remove two (2) drywells and investigate potentially impacted media at 902 Industrial Way, Lodi, San Joaquin County, California. The two (2) drywells provide drainage and disposal for a Fog Curing Concrete System. The water in the Concrete Cure Room is drained into the two (2) drywells. On March 6, 2014 the San Joaquin Environmental Health Department (EHD) inspected the drainage system and deemed it an inadequate waste water disposal method. The waste fluids are not defined as hazardous; however, a potential to contaminate groundwater still exists. The wells are therefore classified as Class V by the Environmental Protection Agency (EPA). EHD approved the Drywell Closure and Investigation Work Plan prepared by NOA, dated March 18, 2014, and revised on March 20, 2014. Work detailed herein was performed in accordance with this work plan. 1.1 Purpose rThe purpose of the activities detailed in this report is to (1) close the two (2) on-site drywells, and (2) determine the presence or absence of impacted soil and/or groundwater as a result of the drywell disposal system. The overall goal of this investigation is to gather appropriate data r 902 Industrial Way•Lodi, CA 95240• 209.367.3701 • Fax 209.333.8303 02014 Neil O.Anderson&Associates, Inc.