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7F COLORADO <br /> Bill Owens,Governor III IIIIIIIIIIIII III <br /> lane E.Norton,Executive Director 999 <br /> Dedicated to protecting and improving the health and environment of the people of Colorado <br /> 4300 Cherry Creek Dr.S. Laboratory and Radiation Services Division •„ � <br /> Denver,Colorado 80246-1530 8100 Lowry Blvd. •rere <br /> Phone(303)692.2000 Denver CO 80220-6928 <br /> Located in Glendale,Colorado (303)692.3090 _ (Al0t1d0 Crt[ <br /> 1 y-I' "f r'( to Public Health <br /> htrp:ffwww.cdphe.sta te.co.us <br /> and Fnvirorunent <br /> July 16, 1999 <br /> Joby AdamsBcloy; <br /> CGRS <br /> P. 0. Box 1489 <br /> Fort Collins, CO 80522 <br /> RE: Point of Compliance Location <br /> Proposed Varra Coal Ash Pilot Project <br /> Weld County <br /> Dear Mr. Adams: <br /> This letter is a response to your request for clarification on the location of the point of <br /> compliance (POC) wells for the above referenced pilot project. During our meeting last month <br /> we briefly discussed the appropriate location for the POC wells. However, do to this unique <br /> proposal (placing coal ash into a saturated media), we deferred our official response until staff of <br /> the Solid Waste Unit of the Hazardous Materials and Waste Management Division and <br /> Assessment Unit of the Water Quality Control Division had time to evaluate the relevant location <br /> for the POC wells. <br /> When considering an appropriate location for the POC wells, it is the staff s judgement that a <br /> conservative ground water monitoring network is pertinent and necessary because of the <br /> uncertainties regarding the mobility and persistence of potential contaminants in the environment <br /> are unknown. To this end, action level (AL) monitoring wells shall be constructed as close as <br /> practical downgradient of the disposal trench. The AL wells will function as an"early waming" <br /> serving two functions: (1) act as a predictor of potential groundwater impact, and (2) act as an <br /> escape mechanism short of compliance and enforcement upon ground water exceedances. Should <br /> the concentration of any constituent on the "target list" show increasing levels or exceed a <br /> maximum contaminant level (MCL) at any AL well, an immediate evaluation of the site <br /> conditions shall occur. If it is determined through confirmatory sampling that any parameter <br /> exceeds an MCL, disposal operations shall stop and the waste removed from the trench. <br /> The POC wells shall be established approximately 50 feet downgradient from the AL monitoring <br /> wells. If any constituent from the target list exceeds its MCL, and is confirmed by additional <br /> sampling, disposal operations shall stop and the coal ash removed from the trench. <br /> Additionally, one property boundary well must be installed to monitor groundwater quality <br /> leaving the site. <br /> I <br />