HomeMy WebLinkAbout950573.tiffSTATE f COLORADO
Roy Romer, Governor
Patti Shwayder, Acting Executive Director
Dedicated to protecting and improving the health and environment of the people of Colorado
HAZARDOUS MATERIALS AND WASTE MANAGEMENT DIVISION ice' rr`
4300 Cherry Creek Or. S.
Denver, Colorado 80222-1530
Phone (303) 692-3300
Fax (303) 759-5355
February 7, 1995
222 S. 6th Street, Room 232
Grand Junction, Colorado 81501-2768
Phone (303) 248-7164
Fax (303) 248-7198
Bill Hedberg
Waste Services Corporation
6037 77th Avenue
Greeley, Colorado 80634
RE: Remedial Goals and Point of Compliance
Central Weld Sanitary Landfill
Weld County
Colorado Deparunent
of Public Health
and Environment
Dear Mr. Hedberg:
The Solid Waste Section of the Hazardous Materials and Waste Management Division (the
Division) has reviewed your letters dated December 9, 1994 and January 16, 1995. These
letters address many issues pertaining to the above referenced facility's correct action goals,
supplemental ground water monitoring and point of compliance (POC) wells. The following
discussion will address each item separately.
1. You have requested that the ground water point of compliance for this site be
relocated from its existing location, at the landfill footprint, to wells GWMW-15 thru
GWMW-18 installed approximately 150 meters down gradient of the landfill
boundary. The Division's and Weld County Health Department's position on this
matter have been expressed in letters dated December 1, 1994 and January 31, 1995
respectively.
The goal of establishing the POC is to ensure early detection of contamination to the
uppermost aquifer. The uppermost aquifer at this site has been impacted by volatile
organic compounds (VOCs). Although ongoing corrective action appears to be
effective in reducing the concentration of VOCs, it is imperative that the established
POC remain at wells GWMW-4, GWMW-5, GWMW-5N, and GWMW-7, to provide
early detection of a release and continual monitoring of the effectiveness of the
remedial system.
2. The Division agrees with the following recommendations for
outlined in the January 16, 1995 letter:
a) air sparging will continue at GWMW-4, GWMW-5,
GWMW7.
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pLOLo 37
remedial goals as
GWMW-5N and
950573
Mr. Bill Hedberg
February 7, 1995
Page 2
b) initiate air sparging at monitoring well GWMW-15.
c) natural attenuation mechanisms in conjunction with air sparging should aid
in reduction of VOCs in the shallow ground water system at this site.
3. During ongoing remedial activities, quarterly monitoring shall be conducted for wells
GWMW-4, GWMW-5, GWMW-5N, GWMW-7 and GWMW-15. Currently, the
facility is monitoring ground water quality on a quarterly basis. An alternative
frequency for the facility's other monitoring wells may be requested in writing. The
request is subject to approval by the Division and Weld County.
4. Your January 16, 1995 letter proposes monitoring for a target list of VOCs. The
Division approves the select list of VOCs as shown in Table 1. However, those
VOCs previously detected during ground water monitoring at this site shall be added
to the target list. The utilization of the target list is contingent upon demonstration
that a statistically significant increase for Appendix IA & IB parameters has not
occurred.
5. Your January 16, 1995 letter indicates ground water levels have dropped significantly
along the southern landfill footprint. Include a table and/or graph which illustrates
the changes in ground water elevations that have occurred subsequent to installation
of each well.
6. Please provide an update on air sparging activities, include dates and time the system
has been operational for each well, equipment changes that have occurred, and
future goals.
These conclude the Division's comments. Please respond to each of the aforementioned
items. If you have any questions, please contact me at 692-3437.
Roger Doak
Geologist
Solid Waste Section
Hazardous Materials and Waste Management Division
cc: Weld County Commissioners
Weld County Planning
T. Jiricek, Weld County Health Department
W. Herst, Golder Associates
file SW/WLD/CEN 3
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