Laserfiche WebLink
i~ <br />4 <br />. ~,~~,~. <br />UNITED STATES ENVIRONMENTAL PROTECTION AGENCY <br />REGION 8 <br />i~~~ y 999 18^~ STREET - SUfTE 500 <br />~iM~ DENVER CD 80202-7166 <br />http:l/www. epa.g ov/region08 <br />~EC+~~~~p FEB 17 2000 <br />Ref: SEPR-EP r QQO <br />F~~ ~$ ~b~°~y <br />N;~CR <br />r.Oti <br />:~~~. <br />Ms. Katlileen Reilly <br />Outreach and Assistance Unit <br />Water Quality Control Division <br />Colorado Department of Public Health and Environment <br />4300 South Cherry Creek Drive <br />Denver, Colorado 80246-1530 <br />RE: ClariScation on Recommendations for <br />Ground-Water Monitoring in the San Luis <br />Area <br />Dear Ms. Reilly: <br />In my letter to you dated January 18, 2000, I provided an evaluation of ground-water flow <br />in the azea azound the Town of San Luis with a simplistic analytically estimated time of travel <br />from the Battle Mountain Gold facility to the town's drinking water-supply wells. The approach <br />used for this estimate follows the methods of the State's Wellhead Protection Program which <br />uses simplistic, ultraconservative analytical methods for drinking water protection. I would like <br />to clarify the approach and purpose of this work in regard to the San Luis Water and Sanitation <br />District's (SLWSD) monitoring project. <br />Current State policy on drinking water protection within the EPA-approved Wellhead <br />Protection and Source Water Assessment and Protection programs calls for the delineation of <br />wellhead protection azeas (WHPAs) /source water assessment areas (SWAAs) using analytical <br />methods based on ultraconservative assumptions (ie,, single input values for aquifer properties <br />that may not be entirely representative of the most probable pathway that the contaminants might <br />take to a well and no consideration of dilution, dispersion, or other contaminant attenuation <br />mechanisms). The methods employed for WHPA/SWAA delineation use simple equations based <br />either on volumetric flow concepu or on Dazcy's Law. State policy is to use a 5-yeaz time of <br />travel in the determination of.WHPAs/SWAAs for use in these programs. The 5-year time of <br />travel is used by the State and locals in order to determine those potential sources of <br />~Prinfed on Recycled Paper <br />