Laserfiche WebLink
San Joaquin County DIRECTOR <br /> Environmental Health Department ASSISTANT DIRECTOR <br /> 600 East Main Street Laurie Cotulla, REHS <br /> Stockton, California 95202-3029 <br /> PROGRAM COORDINATORS <br /> Mike Huggins, REHS,RDI <br /> Phone: (209)468-34:10 Robert McClellon,REHS <br /> Fax: (209) 464-0138 Jeff Carruesco, REHS, RDI <br /> FORMER AMERICAN FOREST PRODUCT <br /> 2801 WEST LANE <br /> STOCKTON CA <br /> RE: FORMER AMERICAN FOREST PRODUCT <br /> 2801 WEST LANE <br /> STOCKTON CA <br /> San Joaquin County Environmental Health Depailment (EHO) has reviewed site data <br /> and the Revised Draft Work Plan and Prefiminajy Site Hydrologic Conceptual Model <br /> Additional 1,2-DCA Investigation (WP) dated May 4, 2007, submitted on your behalf by <br /> URS Corporation Americas (URS) and has the following comments. <br /> In the WP, URS proposes to investigate data gap- for 1,2-dichloroethane (1,2-DCA) by <br /> installing four monitoring wells DMW-10, DMW-11 downgradient to the north, and <br /> DMW-12, and DMW-13 crossgradient to the east and west. The proposed construction <br /> of these wells is to be similar to monitoring well DMW-9, screen interval 60 to 70 feet <br /> below surface grade (bsg), which is in the intermediate ground water zone approximately <br /> 52-72 feet bsq. The DMW-9 water sample contained 24 micrograms per liter (yg/1) 1,2- <br /> DCA during 1 quarter 2007. <br /> EHD approves the proposed installation of DMW-10, DMW-12, and DMW-13 but does <br /> not approve DMW-11. The proposed location for DMW-11 is downgradient from <br /> DMW-10 and would not be a useful data point if DMW-10 shows no impact of 1,2-DCA. <br /> If DMW-10 is shown to be impacted, an additional downgradient monitoring well may be <br /> Upon review of site data, it appears that 1,2-DCA as not been adequately delineated in <br /> the shallow ground water zone approximately 22 to 52 feet bsg or in the deeper <br /> groundwater zone approximately 80 to 90 feet bsg. As for the shallow groundwater zone, <br /> DM1W-6 (screened 32 to 52 feet bsg) contained 19.ug/l 1,2-DCA during first quarter 2007 <br /> and is delineated toward the southwest by DMW- (screened 30 to 65 feet bsg) which <br /> has not been impacted by 1,2-DCA. There are no other monitoring wells on-site <br /> screened in this shallow ground water zone. EHD recommends that additional <br /> groundwater monitoring wells be installed to delir eate 1,2-DCA impact in the shallow <br /> ground water zone. As for the deeper groundwater zone, DMW-8 (screened 80 to 90 <br /> .~~^ ~~g" has shown ... impact. of 1,2-DCA. However, <br /> impacted source area and is screened in. fine grained soil, therefore, the vertical <br /> delineation of 1,2-DCA is not convincingly demonstrated. EHD recommends that a CPT <br /> boring for grab water samples be advanced in cose proximity to the source area to <br /> delineate the vertical extent of 1,2-DCA impacted groundwater. <br /> | <br />� °= | <br />