Appendix C WELL CLOSURE CRITERIA



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# M9800114Appendix C
In June 1988, the Final Decision Document for the Interim Response Action for the Closure ofAbandoned Wells at Rocky Mountain Arsenal was issued by the U.S. Department of the Army (Army). This final documentwas issued followingreview and comment byRegion VIII U.S. Environmental Protection Agency (EPA) and the Colorado Department ofHealth. This Interim Response Action (IRA) included only onpost wells inits coverage. EPA proposed modification ofthis IRA to include offpostwells in a letter to theArmy dated March 15, 1990. EPA proposed criteria for the selection ofwells to be abandoned and closed in the Offpost StudyArea. Ina letter datedJune 13, 1991 (U.S. Army, 1991) to the Colorado Department ofPublic Health and Environment (CDPHE), theArmy agreedin principle with the EPA request to modify the Well Closure IRAto include wellsmeeting the criteria in the Offpost Studv Area.
The following set ofcriteria were developedto identify wellsto be abandoned in the Offpost Study Area.

I. Oftpost wells willbe abandoned according to theregulations setforth by the Office ofthe State Engineer a. if the well is completed in one or more aquifers belowthe alluvial aquifer, and b. if the well isjudged to be ofimproper construction or is in deteriorating condition such that it is leaking from the alluvial aquiferto lower aquifers as indicated by physical parameters (suchas hardness and conductivitymeasurements), and C. if the well contains contaminants which originatedfrom RMA in excess ofthe remediation goals. 2. Offpost wells will be monitored a minimum ofannually a. ifthe well is completed in one ormore aquifers belowthe alluvial aquifer, and b. ifthe well is within 500 feet ofa groundwater plumewhich originated from the RMA, or C. ifthe well isjudged to be ofimproper construction or is indeteriorating condition such that it is leaking from the alluvial aquifer to lower aquifers as indicated byphysical parameters (suchas hardness and conductivity measurements), and d. if the well contains contaminants originating from the RMA at any level. 3. If,based on current water table data, the well islocated in an area of dry alluvium,the well will not be considered a candidate for closure. 4. Wells located onthe property currently ownedby Shell are included in this well closure plan.
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5. Well closure will be at the expense ofthe United States. 6. Well closure methods will be identical to those used for the closure ofonpost wells. 7. The United States and the Department ofthe Army are removed from liability for dealing with unpermitted wells. 8. Following identification of wells meeting all ofthe criteria listed in item 2 above, the Tri-County Health Department (TCHD) will notify individual well owners informing them of suspected faulty construction and request permission to enter the property and abandon the well. THCD will inform the Army if and when permissionhas beenreceived from the well owner to close the well. 9. Well closure expenses will notbe borne bythe United States in the event that unused wells are listed for closure and the well owner is known. Pursuant to Rule 11.1.1, Abandonment Standards (2 Code of Colorado Regulations 402-2), it is the responsibility ofthe well owner to have an unused well properly plugged and abandoned.
A list of wells meeting the closure criteria will be compiled at a meeting ofthe parties' technical staff. A list of wells to be monitored will also be compiled. A consensus will be reached on guidelines to be used to evaluate the hardness and conductivity data. At the time ofthe five year review the monitoring information will be reviewed and it will be determined bythe par-ties if a continued monitoring ofwells in the deeper aquifers is warranted.

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REFERENCES Shell Oil Company, 1991, Letter to U.S. Department of the Army,July 3. U.S. Department of the Army, 1991, Letter to Colorado Department of Health, June 13. U.S. Environmental Protection Agency, 1991, Letter to U.S. Department ofthe Army and Shell Oil Company, January 6.

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