SITE INFORMATION AND CORRESPONDENCE_FILE 2

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tr 15600 Harlan Road, Lathrop Page 2 obtaining an NPDES permit from the CVRWQCB. Please contact Mike Negrete at the CVRWQC13 for details on obtaining the NPDES permit once the City of Lathrop has approved of disposal to their storm water disposal system. The IRAP prepared by ERG states that the nearest storm drain is located in the southeast corner of the site. The Stratus February 2005 1 RAP has a map that shows a storm drain east of MW2, which would be closer to MWO-1X and MW3. The [RAP prepared by ERG has an alternate plan for disposal of extracted groundwater if disposal to the storm drain is not approved. The alternate plan is to reduce the number of wells that groundwater will be extracted from, pumping the extracted water into a 20,000-gallon storage tank and having it removed each day by a vacuum truck and transported offsite for disposal. The ]RAP prepared by ERG states that the storage tank would be placed on the north side of the building. It also discusses running above grade double contained piping within the planter that runs north/south on the east side of the property to dispose of the extracted water to the storm drain on the southeast comer of the site and equipping the storage tank with high level shut off alarms to prevent overflow. There was no map provided for the differing proposals that showed exactly where the storage tank would be located and where the above ground piping would be placed. This is a very busy facility and automatic shut off mechanisms should be placed on the storage tank and the piping. Another facility in San Joaquin County had the automatic shut off mechanism fail and untreated water ended up in the storm drain. All precautions should be taken and emergency phone notification provided. Weekly extraction of a limited amount of groundwater(2000 to 5000 gallons) and disposal offsite has been performed at other UST sites as an interim remedial action. This may be another alternative to evaluate. Extraction from different wells offsite as well as onsite could be performed and results evaluated. The costs for each of the above alternatives should be submitted to EHD with details on placement of any water storage tanks, piping, automatic shutoff mechanisms and emergency notification plans so the plan can be evaluated for cost effectiveness. If you have any questions contact me at (209)4683449. Donna Heran, RENS, Director Environmental Health Department Margaret agorio, RENS Program Coordinator Unit IV c: CVRWQCB—Jim Barton Environmental Remediation Group—Jim Keegan