|
San Joaquin Co my DIRECTOR
<br /> po N Donna Heran, REHS
<br /> Environmental Health Department
<br /> ASSISTANT DIRECTOR
<br /> c.t yti� , 600 East Main Street Laurie Cotulla, REHS
<br /> Stockton, California 95202-3029
<br /> PROGRAM COORDINATORS
<br /> Carl Borgman, REHS
<br /> cQC1 F p cWebsite: WWw.sjgov.o ehd Mike Huggins,REHS,RDI
<br /> Phone: 209 468-34-20 Margaret Lagorio,REHS
<br /> Robert McClellon, REHS
<br /> Fax: (209)464-0138 Jeff Carruesco,REHS,RDI
<br /> Kasey Foley, REHS
<br /> IIC WILLIAM BERGVALL D '4 2007
<br /> FORMER AMERICAN FOREST PRODUCT
<br /> 2801 WEST LANE
<br /> STOCKTON CA
<br />-1 RE: FORMER AMERICAN FOREST PRODUCT
<br /> 2801 WEST !_ANE
<br />' San Joaquin County Environmental Health Department (EHD) has reviewed site data
<br /> and the Revised Draft Work plan and Preliminary 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 gaps 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•viiells'--is'to be`'similar to monitoring,well iMW=9;.`screen interval 60 to 70 feet
<br /> below sdiface'gradet(bsg) auvhieh=is in,th"e=interme iate ground:Water zone:approximately,-
<br /> 52=72:'feet �bsgl*The::DMW-:9'-wateraa'nriple=contai ed,�24 rxmicrograms3per_liter,,~ 1 2=
<br /> DCA``tfuring'15t-quarter'2007
<br /> ,.
<br /> EHD.'approves..the proposed installation of-DMIN',1Q`,DMW 12,�and.DMW-1`3 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 for be impacted, an additional downgradient monitoring well may be
<br /> appropriate.
<br /> Upop.review of site data,-it appears that 1,2-DCA has not been adequately delineated in
<br /> the :shallow ground water zone ,approximately 32 to 52 feet bsg or in the deeper
<br /> groundwater zone approximately 80 to 90 feet bsg. As f0Fthe' shallow groundwater zone., -
<br /> DMW-6 (screened 32 to 52 feet bsg) contained,19 gll 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 areno other, monitoring .wells on-site
<br /> screened ' in this, shallow ground water. zone: -EHD recommends. that 'additional
<br /> groundwater monitoring wells b'"installed 4o'd Ii Bate 1,2-DCA impact in the shallow
<br /> ground water,zone..As for_the..d!Dp;per grp66dwat r`zone,',DMW=8 (screened 80 to g0
<br /> fe6t'bsg) ;has shown no"impact'of"`1;2-DCA.'°Ho ever;,DMW-8 is not Idcated`'�in the
<br /> impact&d,.f+source','arbei?,and is screened in. fine grained soil, therefore, the vertical
<br /> belinieatioh of=`1,2 DCXiis:inbtrconvincingly demons rated.tE.HD;:tecominends,,tf atia)QF?T-
<br /> #�o'ririg for.`grab water sam Iles:l e ?a'dvaniced-Fin_ cl se=.proximity..to ,thecsource,area�tb
<br /> 'delinea'te'thd'=vertidal'ed tent?of IC,21-DCA impacted g oundwater.:. --of
<br /> Y
<br />
|