SITE INFORMATION AND CORRESPONDENCE_FILE 2

Home Browse Search

i September'14, 2010 Messrs. Kirk Larson, PG, and Robert Trommer, CHG State Water Resources Control Board Division of Financial Assistance 1001 1 Street Sacramento CA 95814 Subject: .2969 E. Loomis Road, Stockton, August 2010 Draft Five-Year Review Recommendations San Joaquin County Environmental Health Department (EHD) has received and reviewed the annual five-year review update letter dated 23 August 2010 from Kirk Larson of the State Water Quality Control Board (SWQCB) Cleanup Fund (CUF) for the above-referenced site. The CUF recommendation for 2010 is for the same as was recommended in 2009: site closure consideration. By email dated 10 April 2009, the EHD had responded 'to the draft 5-Year Review letter recommending site closure consideration by noting technical concerns that the EHD believes make site closure consideration premature for,the subject site. The EHD also noted these concerns by letter dated 03 March 2010 addressed to Robert Trommer who had solicited comments on various sites the CUF had previously recommended for closure consideration. The EHD had requested comment from:Mr. Trommer or the CUF technical staff regarding the EHD concerns listed below: • Groundwater is at least 5 feet over screen in all monitoring wells, and approximately 20 feet over screen in the initial four groundwater monitoring wells, therefore the vadose zone-water table interface isnot directly monitored; • The residual TPHd mass has been estimated at 168,000 pounds, which the EHD believes to be a significant mass; • A major decline of dissolved contaminant concentrations was observed in April 2008 in all monitoring well samples, examination of the data shows that this decline coincided exactly with a change of analytical laboratories; split samples collected at a later date further demonstrated the laboratory effect. Which laboratory data is correct is beyond the purview and expertise of the EHD, but the associated estimated 168,000 pound TPHd mass suggests the higher.concentration may be closer to the mark; The mixed commercial and residential area around the subject site is not serviced by a municipal water system; the closest municipal well is approximately 2,300 feet from the site. A sensitive receptor survey included in the 2006 site conceptual model identified 38 domestic Draft Annual 5-Year Review Update,Response.doc - , -. —� -- - �». • ..-�« •�6 �_.- --