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P~1RnGON <br />CONSULTING GROUP <br />i ~ i ~ <br />Permit #: -Faq~-a Confidental?: <br />Class: 1 Type-Seq.: <br />From: To: /~~r , <br />Doc. Name: <br />Doc. Date (if no da a stamp): %/~~/ir~. <br />~~P <br />SENT VIA CERTIFIED MAIL <br />Certified Number 7002 1000 0005 7120 0339 <br />September 20, 2002 <br />Ms. Kate Pickford <br />Colorado Division of Minerals and Geology <br />1313 Sherman Street, Room 215 <br />Denver, Colorado 80203 <br /> I I03 Os4 Wk DeWr, Suioe 110 <br /> ~ caaw, co eos7s <br /> Phorc (97q 3771600 <br /> = ~w~~~° <br />RECEIVED <br /> DAwo M. Mu, P.E, DEE <br />SEP 2 3 2002 s~A Rurxmwxo, P.E <br /> Bwat SMrtx, P.E <br /> yue[s M. TxrnlAS, P.E <br />Division of Minerals and Geology BFAOc.w~xln <br />SrevEU A Muu~ P.E <br /> nxr D. w®6,z. ELT <br /> HFA311wt S. Alnwuux <br />RE: July 2002 Quarterly Monitoring Report/Request for Site Closure <br />Aggregate Industries F Street Facility <br />4509 F Street <br />Greeley, Colorado <br />Project Number 1001018 <br />Dear Ms. Pickford: <br />Enclosed are two (2) copies of the July 2002 Quarterly Monitoring Report/Request for Site <br />Closure for the above-referenced site. Petroleum hydrocarbon concentrations were not <br />observed above the laboratory detection limits in groundwater samples collected from the <br />site in July 2002. The July 2002 sampling episode was the fifth event in which benzene- <br />toluene-ethylbenzene-xylenes concentrations were not observed above the Maximum <br />Contaminant Levels in groundwater samples collected from the site. Therefore, it is our <br />opinion that additional monitoring, assessment or abatement is not warranted at the site at <br />this time and site closure should be granted by the Colorado Division of Minerals and <br />Geology for the 2001 diesel-fuel release. <br />As summarized in previous reports, the volume of the diesel-fuel spill was estimated to be <br />approximately 10,840 gallons based on information provided by Aggregate Industries. We <br />attempted to perform a mass balance to compare the amount of diesel fuel released versus <br />the amount of diesel fuel recovered during the soil and groundwater abatement activities. <br />Due to the limited number of impacted samples analyzed from the site, the mass balance <br />indicated that much more diesel fuel was recovered than released. Based on experience and <br />professional judgement, a release of 10,840 gallons would be expected to cause greater <br />impacts than have been observed at the site. The apparent lack of significant impacts <br />appears to indicate that the abatement activities were highly successful in cleaning up the <br />spill and/or that the spill amount was much lower than estimated by Aggregate Industries. <br />Possible explanations for an erroneous spill estimate could be fuel theft or short fuel <br />deliveries. <br />ENVIRONMENTAL ENGINEERING AND GEOHYDROLOGY <br />