EPA Superfund Record of Decision: Rocky Mountain Arsenal (USARMY) EPA ID: CO5210020769 OU 01 Adams County CO 06/04/1987


                                    EPA/ROD/R08-87/001
                                    1987
EPA Superfund
     Record of Decision:
     ROCKY MOUNTAIN ARSENAL (USARMY)
     EPA ID: CO5210020769
     OU01
     ADAMS COUNTY, CO
     06/04/1987

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        -  REMEDIAL  INVESTIGATION FOR THE FIRST OPERABLE UNIT - EPA'S RMA OFF-POST RI/FS  SITE,  DATED DECEMBER
           1986 AND  PREPARED  BY CAMP DRESSER & MCKEE (INCLUDES PUBLIC HEALTH ENDANGERMENT ASSESSMENT)

        -  FEASIBILITY  STUDY  FOR THE FIRST OPERABLE UNIT - EPA'S RMA OFF-POST RI/FS  SITE, DATED DECEMBER 1986
           AND PREPARED BY  CAMP DRESSER & MCKEE

        -  PRELIMINARY  RISK ASSESSMENT OF THE SOUTH ADAMS COUNTY WATER AND SANITATION  DISTRICT  WATER
           DISTRIBUTION SYSTEM,  DATED APRIL 17, 1986 AND PREPARED BY CLEMENT ASSOCIATES,  INC. FOR CAMP
           DRESSER & MCKEE

        -  TREATABILITY/FEASIBILITY STUDY FOR DISTRICT WATER QUALITY IMPROVEMENT, DATED MAY 1986 AND PREPARED
           BY JAMES M.  MONTGOMERY CONSULTING ENGINEERS INC. FOR SOUTH ADAMS COUNTY WATER  AND SANITATION
           DISTRICT

        -  DETAILED ANALYSIS  FOR ORGANIC CONTAMINANT REMOVAL, DATED OCTOBER 1986 AND PREPARED BY BLACK AND
           VEATCH FOR SOUTH ADAMS COUNTY WATER AND SANITATION DISTRICT.

        -  SUMMARY OF REMEDIAL  ALTERNATIVE SELECTION (ATTACHED HERETO)

        -  RESPONSIVENESS SUMMARY (ATTACHED HERETO)

        -  STAFF SUMMARIES  AND  BRIEFING DOCUMENTS.

#DE
DECLARATIONS

CONSISTENT WITH THE  COMPREHENSIVE ENVIRONMENTAL RESPONSE, COMPENSATION AND LIABILITY ACT  OF 1980 (CERCLA),  AS
AMENDED BY THE SUPERFUND AMENDMENTS AND REAUTHORIZATION ACT OF 1986  (SARA), AND THE  NATIONAL CONTINGENCY
PLAN, 40 CFR PART 300,  I HAVE DETERMINED THAT CONSTRUCTION OF A GRANULAR ACTIVATED CARBON WATER TREATMENT
FACILITY TO TREAT CONTAMINATED  GROUND WATER UNDERLYING THE EPA OFF-POST RI/FS SITE IS  A COST-EFFECTIVE
OPERABLE UNIT REMEDIAL  ACTION,  IS PROTECTIVE OF HUMAN HEALTH, AND IS CONSISTENT WITH POSSIBLE FUTURE REMEDIAL
ACTIONS.  THE SELECTED  REMEDY INCLUDES THE POSSIBLE ADDITION OF AN AIR STRIPPING FACILITY,  AS APPROPRIATE TO
ASSURE PROTECTION OF HUMAN  HEALTH,  IN THE EVENT THAT VINYL CHLORIDE CURRENTLY IDENTIFIED  UPGRADIENT OF THE
SACWSD WELLS POSES A THREAT TO  THE SACWSD WELLS.  THE SELECTED REMEDY ALSO PROVIDES  FOR THE REPLACEMENT OF
EXISTING WELL PUMPS AND MOTORS,  THE INSTALLATION OF TRANSMISSION PIPING, AND THE CONSTRUCTION OF LABORATORY
AND OFFICE SPACE.  UNTIL THE  PERMANENT GAG SYSTEM IS ON LINE, THE SELECTED REMEDY PROVIDES  FOR  CONTINUED
LEASING OF THE TEMPORARY GAG  SYSTEM CURRENTLY IN PLACE.

THE SELECTED REMEDY UTILIZES  PERMANENT SOLUTIONS AND TREATMENT TECHNOLOGIES TO THE MAXIMUM  EXTENT PRACTICABLE
FOR CONTAMINANTS IDENTIFIED TO  DATE IN SACWSD DRINKING WATER SUPPLY WELLS  (GAG TREATMENT  WITH INCINERATION OF
SPENT CARBON AT ANOTHER LOCATION)  FOR THIS OPERABLE UNIT.  THE SELECTED REMEDY FOR THIS OPERABLE UNIT WILL
REDUCE THE VOLUME AND THE TOXICITY AND MOBILITY OF CONTAMINANTS IDENTIFIED IN SOUTH  ADAMS COUNTY DRINKING
WATER TO DATE THROUGH INCINERATION OF THE VOLATILE ORGANIC COMPOUNDS ADSORBED ON THE GRANULAR ACTIVATED
CARBON WHEN THE CARBON  IS REGENERATED.  SPENT CARBON FROM THE GAG TREATMENT SYSTEM WILL BE  REGENERATED AT AN
INCINERATOR IN COMPLIANCE WITH  SECTIONS 3004 AND 3005 OF THE SOLID WASTE DISPOSAL ACT  (SWDA)  AND SECTION
121(D)(3) OF CERCLA.

THE APPLICABLE OR RELEVANT  AND  APPROPRIATE REQUIREMENTS FOR THIS OPERABLE UNIT ARE THE MAXIMUM  CONTAMINANT
LEVELS  ("MCLS") ESTABLISHED UNDER THE SAFE DRINKING WATER ACT ("SDWA") FOR HAZARDOUS SUBSTANCES,  POLLUTANTS,
OR CONTAMINANTS IDENTIFIED  IN SOUTH ADAMS COUNTY DRINKING WATER.  UNDER THE SDWA, CONGRESS  ESTABLISHED A
TWO-PRONGED APPROACH FOR DETERMINING PERMISSIBLE LEVELS OF CONTAMINANTS IN WATER WHICH IS DELIVERED TO ANY
USER OF A PUBLIC WATER  SYSTEM:   (1)  MAXIMUM CONTAMINANT LEVEL GOALS  ("MCLGS") ARE TO BE SET AT  THE LEVEL AT
WHICH NO KNOWN OR ANTICIPATED ADVERSE EFFECTS ON HEALTH OF PERSONS OCCUR AND WHICH ALLOWS AN ADEQUATE MARGIN
OF SAFETY; AND  (2) MCLS ARE TO  BE SET AS CLOSE TO THE MCLG AS IS FEASIBLE.  SECTION  1412(B)(4)  OF THE SDWA.
MCLGS ARE NON-ENFORCEABLE HEALTH GOALS.  MCLS ARE ENFORCEABLE REQUIREMENTS WHICH SPECIFY  THE MAXIMUM
PERMISSIBLE LEVEL OF A  CONTAMINANT IN WATER WHICH IS DELIVERED TO ANY USER OF A PUBLIC WATER SYSTEM.
SECTION 1401(3) OF THE  SDWA.

CONGRESS DEFINED THE TERM FEASIBLE TO MEAN:

        ... WITH THE USE OF  THE  BEST TECHNOLOGY, TREATMENT TECHNIQUES, AND OTHER MEANS  WHICH THE ADMINISTRATOR
       FINDS, AFTER  EXAMINATION FOR EFFICACY UNDER FIELD CONDITIONS AND NOT UNDER LABORATORY CONDITIONS,  ARE
       AVAILABLE  (TAKING COST INTO CONSIDERATION)  	  GRANULAR ACTIVATED CARBON IS  FEASIBLE FOR THE CONTROL
       OF SYNTHETIC  ORGANIC CHEMICALS, AND ANY TECHNOLOGY, TREATMENT TECHNIQUE, OR OTHER  MEANS  FOUND TO BE
       THE BEST AVAILABLE FOR THE CONTROL OF SYNTHETIC ORGANIC CHEMICALS MUST BE AT  LEAST AS EFFECTIVE IN
       CONTROLLING SYNTHETIC  ORGANIC CHEMICALS AS GRANULAR ACTIVATED CARBON.".

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SECTION 1412 (B) (5) OF THE SDWA.

THE SELECTED REMEDIAL ACTION FOR THIS OPERABLE UNIT IS A GRANULAR ACTIVATED CARBON TREATMENT SYSTEM. IN
SELECTING GAG, EPA IS UTILIZING A TECHNOLOGY WHICH CONGRESS EXPLICITLY RECOGNIZED AS FEASIBLE UNDER THE SAFE
DRINKING WATER ACT. ID. MOREOVER, BY SPECIFYING MCLS AS THE APPLICABLE OR RELEVANT AND APPROPRIATE
REQUIREMENT THAT CANNOT BE EXCEEDED FOR THIS OPERABLE UNIT, EPA IS IMPLEMENTING AND ACTING CONSISTENTLY WITH
THE STATUTORILY MANDATED PROCESS AND CRITERIA THAT CONGRESS PRESCRIBED FOR ALL PUBLIC DRINKING WATER SYSTEMS
NATIONWIDE. IN ADDITION, THE MCLS SELECTED AS APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS FOR THIS
OPERABLE UNIT FOR CONTAMINANTS IDENTIFIED IN SOUTH ADAMS COUNTY DRINKING WATER ASSURE ADEQUATE PROTECTION OF
HUMAN HEALTH.

FOR THE ABOVE REASONS, EPA HAS SELECTED MCLS AS THE LEGALLY APPLICABLE OR RELEVANT AND APPROPRIATE
REQUIREMENT WHICH THE SELECTED REMEDY MUST AT LEAST ATTAIN FOR THIS OPERABLE UNIT. 1.

SECTION 121(D)(2)(A) OF CERCLA PROVIDES THAT REMEDIAL ACTIONS "REQUIRE A LEVEL OR STANDARD OF CONTROL WHICH
AT LEAST ATTAINS (MCLGS) ... WHERE SUCH GOALS ... ARE RELEVANT AND APPROPRIATE UNDER THE CIRCUMSTANCES OF THE
RELEASE.". THIS LANGUAGE, ON ITS FACE, AND SECTION 121 OF CERCLA, TAKEN AS A WHOLE, GIVES EPA THE DISCRETION
TO DETERMINE, IN LIGHT OF THE SPECIFIC FACTS AT CERCLA SITES, WHETHER MCLGS ARE RELEVANT AND APPROPRIATE. IT
IS WITHIN THE AGENCY'S DISCRETION TO DETERMINE THAT MCLS ARE THE APPLICABLE OR RELEVANT AND APPROPRIATE
CLEANUP STANDARDS BASED ON THE CIRCUMSTANCES PRESENT AT THIS SITE. FOR THIS PARTICULAR OPERABLE UNIT,
ADDITIONAL FACTORS ARE NOT PRESENT WHICH SUGGEST THE NEED TO ATTAIN MCLGS IN ORDER TO ASSURE PROTECTION OF
HUMAN HEALTH. THEREFORE, THE AGENCY HAS DETERMINED THAT MCLGS ARE NOT RELEVANT AND APPROPRIATE UNDER THE
CIRCUMSTANCES OF THIS OPERABLE UNIT.

SPECIFICALLY, THE SELECTED REMEDY SHALL AT LEAST ATTAIN, AND SHALL IN NO CIRCUMSTANCES EXCEED, THE FOLLOWING
LEVELS FOR HAZARDOUS SUBSTANCES, POLLUTANTS OR CONTAMINANTS IDENTIFIED IN SOUTH ADAMS COUNTY DRINKING WATER:
(1) PROPOSED MCLS FOR VOLATILE SYNTHETIC ORGANIC CHEMICALS. SEE 50 FED. REG. 46902 (NOV. 13, 1985); AND (2)
FINAL MCLS. TABLE A SETS FORTH EPA'S FINAL AND PROPOSED MCLS. IN THE EVENT THAT MCLS ARE REVISED, OR
AMENDED TO INCLUDE ADDITIONAL CONTAMINANTS IDENTIFIED IN SOUTH ADAMS COUNTY DRINKING WATER, THE AGENCY WILL
EVALUATE SUCH REVISED OR AMENDED MCLS AND AMEND THE RECORD OF DECISION, IF APPROPRIATE, TO REQUIRE THAT THE
REMEDY ATTAIN THE REVISED OR AMENDED MCLS AND ASSURE ADEQUATE PROTECTION OF HUMAN HEALTH.

NATIONAL EMISSION STANDARD FOR HAZARDOUS AIR POLLUTANTS (NESHAPS), ESTABLISHED UNDER THE CLEAN AIR ACT, FOR
VINYL CHLORIDE AND BENZENE, ARE RELEVANT AND APPROPRIATE IN THE EVENT THAT AIR STRIPPING IS REQUIRED TO TREAT
VINYL CHLORIDE (40 CFR PART 61, SUBPARTS F AND J).

PRETREATMENT STANDARDS PROMULGATED PURSUANT TO SECTION 307 OF THE CLEAN WATER ACT ARE APPLICABLE OR RELEVANT
AND APPROPRIATE IN THE EVENT THAT THE SELECTED REMEDY INVOLVES THE DISCHARGE, INDIRECT DISCHARGE, OR
INTRODUCTION OF POLLUTANTS INTO A PUBLICLY OWNED TREATMENT WORKS FROM A SOURCE REGULATED UNDER SECTIONS
307(B), (C), OR (D) OF THE CLEAN WATER ACT. THE REMEDY CURRENTLY DOES NOT CONTEMPLATE SUCH A DISCHARGE,
INDIRECT DISCHARGE OR INTRODUCTION OF POLLUTANTS.

THIS DEGREE OF CLEANUP WILL ASSURE PROTECTION OF HUMAN HEALTH UNDER THIS OPERABLE UNIT. THE SELECTED
REMEDIAL ACTION IS RELEVANT AND APPROPRIATE UNDER THE CIRCUMSTANCES OF THE RELEASE OR THREATENED RELEASE OF
THE HAZARDOUS SUBSTANCES, POLLUTANTS, OR CONTAMINANTS OF CONCERN IDENTIFIED TO DATE IN SACWSD DRINKING WATER
SUPPLY WELLS.
1. APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS ARE SELECTED ON A SITE-SPECIFIC BASIS. THE
SELECTION OF MCLS AS THE APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENT FOR THIS OPERABLE UNIT IS
NOT INTENDED TO ESTABLISH PRECEDENT FOR REMEDIAL ACTION AT OTHER SITES OR OPERABLE UNITS, INCLUDING,
BUT NOT LIMITED TO, GROUND WATER AND SURFACE WATER RESTORATION, AND IS NOT INTENDED TO ESTABLISH
PRECEDENT FOR ANY CONTAMINANTS NOT IDENTIFIED IN SOUTH ADAMS COUNTY DRINKING WATER.

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THE STATE OF COLORADO PROVIDED EPA WITH A LIST OF APPLICABLE OR RELEVANT AND APPROPRIATE STATE STANDARDS,
REQUIREMENTS, LIMITATIONS, OR CRITERIA ("STATE REQUIREMENTS") FOR THIS OPERABLE UNIT ON JANUARY 8, 1987. THE
STATE AMENDED ITS LIST ON MARCH 17, 1987 TO DELETE SEVERAL REQUIREMENTS AND ADD AN ADDITIONAL REQUIREMENT.
EPA HAS REVIEWED THE PROPOSED STATE REQUIREMENTS UNDER THE CRITERIA SET FORTH IN SECTION 121 (D) OF CERCLA,
AND DETERMINED THAT CERTAIN PROVISIONS WITHIN THE FOLLOWING STATE REQUIREMENTS GENERALLY ARE APPLICABLE OR
RELEVANT AND APPROPRIATE:

1. THE COLORADO HAZARDOUS WASTE ACT AND REGULATIONS

APPLICABLE TO THE EXTENT THE SELECTED REMEDY INVOLVES THE GENERATION, TRANSPORTATION, TREATMENT, OR
STORAGE OF HAZARDOUS WASTE IN THE SPENT GRANULAR ACTIVATED CARBON. THE SELECTED REMEDY DOES NOT
CONTEMPLATE DISPOSAL OF HAZARDOUS WASTE.

2. THE COLORADO PRIMARY DRINKING WATER REGULATIONS

APPLICABLE OR RELEVANT AND APPROPRIATE TO THE DRINKING WATER WHICH WILL BE SUPPLIED TO THE PUBLIC
THROUGH THE SELECTED REMEDY, FOR CONTAMINANTS IDENTIFIED IN THE GROUND WATER WHICH SUPPLIES THE
SACWSD SUPPLY WELLS.

3. THE COLORADO AIR QUALITY CONTROL REGULATIONS

APPLICABLE OR RELEVANT AND APPROPRIATE TO FUGITIVE PARTICULATE EMISSIONS AND EMISSIONS WHICH MAY
RESULT FROM THE SELECTED REMEDY IF AIR STRIPPING OF VINYL CHLORIDE IS REQUIRED, OR IF STORAGE OR
TRANSFER OF VOLATILE ORGANICS COMPOUNDS IS REQUIRED.

4. THE COLORADO NOISE ABATEMENT STATUTE

APPLICABLE OR RELEVANT AND APPROPRIATE TO ESTABLISH MAXIMUM PERMISSIBLE NOISE LEVELS FOR
CONSTRUCTION OR OPERATION OF THE SELECTED REMEDY.

5. THE COLORADO WILDLIFE STATUTES AND REGULATIONS

APPLICABLE TO THE EXTENT THE SELECTED REMEDY INVOLVES THE TAKING, POSSESSION, TRANSPORTATION,
EXPORTATION, SHIPMENT, REMOVAL, CAPTURE, OR DESTRUCTION OF WILDLIFE. THE SELECTED REMEDY DOES
NOT CONTEMPLATE ANY OF THESE ACTIVITIES.

6. THE WATER WELL AND PUMP INSTALLATION CONTRACTOR ACT AND REGULATIONS

APPLICABLE OR RELEVANT AND APPROPRIATE TO PUMP INSTALLATION. THE SELECTED REMEDY DOES NOT
CONTEMPLATE THE CONSTRUCTION OF WATER WELLS.

7. HISTORICAL, PREHISTORICAL, AND ARCHAEOLOGICAL RESOURCES ACT

APPLICABLE OR RELEVANT AND APPROPRIATE IF THE SELECTED REMEDY INVOLVES THE INVESTIGATION,
EXCAVATION, GATHERING OR REMOVAL FROM THE NATURAL STATE OF ANY HISTORICAL, PREHISTORICAL, AND
ARCHAEOLOGICAL RESOURCES WITHIN THE STATE. THE SELECTED REMEDY DOES NOT CONTEMPLATE ANY OF THESE
ACTIVITIES.

8. THE COLORADO WATER QUALITY CONTROL ACT AND REGULATIONS

APPLICABLE OR RELEVANT AND APPROPRIATE TO THE EXTENT THE SELECTED REMEDY INVOLVES THE DISCHARGE OF
POLLUTANTS TO WATERS OF THE STATE OF COLORADO. THE SELECTED REMEDY DOES NOT CONTEMPLATE SUCH A
DISCHARGE.

A DETAILED EVALUATION OF THE STATE REQUIREMENTS IS SET FORTH IN APPENDIX B. THE SELECTED REMEDY WILL AT
LEAST ATTAIN THE LEGALLY APPLICABLE OR RELEVANT AND APPROPRIATE STATE REQUIREMENTS IDENTIFIED IN APPENDIX B.

THE STATE OF COLORADO AND THE SACWSD HAVE BEEN CONSULTED AND CONCUR WITH THE SELECTED REMEDY (APPENDIX C).
THE ACTION WILL REQUIRE FUTURE OPERATION AND MAINTENANCE ACTIVITIES TO ASSURE THE CONTINUED EFFECTIVENESS OF
THE REMEDY.

THE AGENCY FOR TOXIC SUBSTANCES AND DISEASE REGISTRY (ATSDR) REVIEWED THE REMEDIAL INVESTIGATION AND
FEASIBILITY STUDY REPORTS, INCLUDING THE PUBLIC HEALTH EVALUATIONS, AND STATED THE OPINION THAT "ANY OF THE
PROPOSED REMEDIAL ALTERNATIVES FOR TREATMENT OF THE SOUTH ADAMS COUNTY WATER AND SANITATION DISTRICT (SACWSD)
GROUND WATER WILL ACHIEVE THE NECESSARY TREATMENT REQUIRED TO PROTECT PUBLIC HEALTH.". ATSDR1S CONCURRENCE
IS INCLUDED IN THE ADMINISTRATIVE RECORD.

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PURSUANT TO AN AGREEMENT ENTERED INTO BETWEEN THE ARMY AND EPA ON SEPTEMBER 26, 1986, THE SELECTED RESPONSE
ACTION FOR THIS OPERABLE UNIT WILL BE PARTIALLY FINANCED BY THE U.S. ARMY. THE SELECTED REMEDY IS A
COST-EFFECTIVE RESPONSE MEASURE NECESSARY TO ABATE, MINIMIZE, STABILIZE, MITIGATE, OR ELIMINATE THE THREAT
POSED TO PUBLIC HEALTH BY TCE IN SOUTH ADAMS COUNTY DRINKING WATER. TO THE EXTENT THAT ARMY OR OTHER PRP
FUNDS ARE USED FOR THE DESIGN, CONSTRUCTION AND IMPLEMENTATION OF THE RESPONSE ACTION, THE STATE COST SHARE
REQUIREMENTS UNDER SECTION 104 (C) (3) OF CERCLA SHALL NOT APPLY. THE STATE COST SHARE REQUIREMENTS UNDER
SECTION 104 (C) (3) SHALL APPLY TO ANY FUND-FINANCED CONSTRUCTION AND IMPLEMENTATION OF THE SELECTED REMEDIAL
ACTION.

THE EPA WILL CONTINUE ITS COMPREHENSIVE REMEDIAL INVESTIGATION/FEASIBILITY STUDIES FOR THE ENTIRE EPA RMA
OFF-POST RI/FS SITE, AND EXPECTS TO COMPLETE SUCH STUDIES BY ABOUT SPRING OF 1988. THE FEASIBILITY STUDY
WILL EVALUATE WHETHER OR NOT FURTHER RESPONSE ACTIONS ARE NECESSARY AT THE EPA RMA OFF-POST SITE TO PROTECT
HUMAN HEALTH AND THE ENVIRONMENT. FOLLOWING COMPLETION OF THE FS, A RECORD OF DECISION WILL BE PREPARED
ADDRESSING FUTURE RESPONSE ACTIONS, IF ANY. THE SELECTED REMEDY FOR THIS OPERABLE UNIT IS CONSISTENT WITH A
PERMANENT REMEDY.

JUNE 4, 1987 JAMES SCHERER
DATE REGIONAL ADMINISTRATOR
ENVIRONMENTAL PROTECTION AGENCY
US EPA - REGION 8.

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SUMMARY OF REMEDIAL ALTERNATIVE SELECTION
EPA'S RMA OFF-POST RI/FS SITE

#SLD
SITE LOCATION AND DESCRIPTION

THE ROCKY MOUNTAIN ARSENAL (RMA) WAS PROPOSED FOR INCLUSION ON THE NATIONAL PRIORITIES LIST (NPL) IN OCTOBER,
1984. RMA IS A FACILITY OWNED AND OPERATED BY THE UNITED STATES DEPARTMENT OF THE ARMY. RMA WAS ESTABLISHED
IN 1942 WITH THE PRIMARY MISSION OF MANUFACTURING AND ASSEMBLING CHEMICAL AND INCENDIARY MUNITIONS TO SUPPORT
THE WAR EFFORT. SUBSEQUENTLY, PESTICIDES AND HERBICIDES WERE PRODUCED ON-POST BY PRIVATE LEASEES. MANY OF
THESE SUBSTANCES, THEIR BY-PRODUCTS AND RESIDUES WERE DISPOSED ON-POST. THE ARMY IS CONDUCTING RI/FS STUDIES
ON-POST AND OFF-POST NORTH OF 80TH AVENUE.

EPA'S RMA OFF-POST RI/FS SITE IS LOCATED ABOUT 10 MILES NORTHEAST OF THE DOWNTOWN AREA OF DENVER, COLORADO
AND ADJACENT TO RMA. THE SITE EXTENDS WESTWARD FROM THE ROCKY MOUNTAIN ARSENAL TO THE SOUTH PLATTE RIVER.
THE SOUTHERN BOUNDARY IS FORMED BY 56TH AVENUE AND SAND CREEK, AND THE NORTHERN BOUNDARY BY 80TH AVENUE FROM
THE ARSENAL TO THE SOUTH PLATTE (FIGURE 1). THE SITE ENCOMPASSES A LARGE PART OF THE MUNICIPALITY OF
COMMERCE CITY AND A PORTION OF UNINCORPORATED ADAMS COUNTY. THE AREA IS NEARLY COMPLETELY DEVELOPED WITH
RESIDENTIAL SUBDIVISIONS, INDUSTRIAL FACILITIES AND GRAVEL OPERATIONS.

THE SOUTH ADAMS COUNTY WATER AND SANITATION DISTRICT (SACWSD) SUPPLIES APPROXIMATELY 30,000 CUSTOMERS WITH
WATER FROM WELLS COMPLETED IN ALLUVIUM AND BEDROCK WITHIN THE STUDY AREA. RECENT STUDIES COMPLETED BY THE
EPA AND SACWSD IN THE STUDY AREA INDICATE THAT SIGNIFICANT CONCENTRATIONS (100 PARTS PER BILLION RANGE) OF
ORGANIC SOLVENTS ARE PRESENT IN THE LOCAL AND REGIONAL GROUND WATER SYSTEM. PRIVATE WELLS AND SACWSD WELLS
LOCATED WITHIN THE STUDY AREA ARE CONTAMINATED BY ORGANIC SOLVENTS. TWO OF THESE ORGANIC COMPOUNDS —
TRICHLOROETHYLENE - TCE AND 1,1-DICHLOROETHYLENE — WERE REPORTED IN CONCENTRATIONS IN WELLS IN EXCESS OF
MAXIMUM CONTAMINANT LIMITS ESTABLISHED UNDER THE SAFE DRINKING WATER ACT. TO DATE, ORGANIC SOLVENT
CONTAMINATION APPEARS TO BE LIMITED TO THE ALLUVIAL AQUIFER.

#SH
SITE HISTORY

THE MUNICIPALITY OF COMMERCE CITY AND ADJACENT AREAS GREW IN RESPONSE TO THE RAPID POST-WAR PROLIFERATION OF
INDUSTRY NORTH AND EAST OF THE CITY OF DENVER. IN ORDER TO PROVIDE A WATER SUPPLY AND SEWAGE TREATMENT TO
THE RESIDENTS AND BUSINESSES, A SPECIAL GOVERNMENTAL DISTRICT WAS CREATED IN 1953: THE SOUTH ADAMS COUNTY
WATER AND SANITATION DISTRICT (SACWSD). THE SACWSD SUPPLIES ITS APPROXIMATELY 30,000 CUSTOMERS (1986) WITH
WATER FROM WELLS COMPLETED IN ALLUVIUM AND BEDROCK.

UNTIL RECENTLY, HUNDREDS OF PRIVATE SUPPLY WELLS WERE IN USE THROUGHOUT THE SOUTH ADAMS COUNTY AREA. ALMOST
ALL OF THE PRIVATE WELLS TAPPED THE ALLUVIAL AQUIFER. MOST OF THESE PRIVATE WELLS WERE TAKEN OUT OF SERVICE
IN SUMMER 1986 WHEN RESIDENCES WERE CONNECTED TO THE PUBLIC WATER SUPPLY SYSTEM AS PART OF AN EMERGENCY
REMOVAL ACTION CONDUCTED BY EPA. EPA FIELD INVESTIGATION TEAM (FIT) DATA SHOWED THAT WATER FROM THESE WELLS
EXCEEDED SAFE DRINKING WATER ACT CRITERIA FOR VOLATILE ORGANIC COMPOUNDS AND POSED A THREAT TO PUBLIC HEALTH.

CONTAMINATED GROUND WATER CONTAINING ORGANIC SOLVENT COMPOUNDS HAS BEEN DETECTED BY VARIOUS GOVERNMENT
BODIES, INCLUDING EPA, SPORADICALLY SINCE 1981 THROUGHOUT THE EPA OFF-POST RI/FS SITE IN BOTH INDIVIDUAL AND
SACWSD SUPPLY WELLS. THE ROCKY MOUNTAIN ARSENAL, A PROPOSED SITE ON THE NATIONAL PRIORITIES LIST (NPL), HAS
BEEN IDENTIFIED AS ONE OF TWO OR MORE SOURCES OF THE CONTAMINATION. TO DATE, EPA HAS NOT IDENTIFIED
POSITIVELY OTHER SOURCES OF THE CONTAMINATION, BUT SURROUNDING POTENTIAL SOURCES INCLUDE TWO OTHER CERCLA
SITES (SAND CREEK AND WOODBURY) WHICH ARE LISTED ON THE NPL AND ARE DIRECTLY TO THE SOUTH AND SOUTHWEST OF
EPA'S OFF-POST RI/FS SITE, LOCAL INDUSTRIES WITHIN SOUTH ADAMS COUNTY AND UPGRADIENT OF THE SUPPLY WELLS, OR
A COMBINATION OF ANY OF THESE SOURCES. MANY OF THESE OPERATIONS REQUIRE THE USE OF DEGREASING SOLVENTS,
INCLUDING TCE AND OTHER CHLORINATED HYDROCARBONS. ADDITIONAL DATA MUST BE GATHERED TO DETERMINE THE NATURE
AND EXTENT OF CONTAMINATION FROM INDIVIDUAL SOURCES, AND RELATIVE CONTRIBUTIONS FROM SUCH SOURCES.

ON MARCH 20, 1986, THE ARMY SIGNED AN AGREEMENT WITH EPA UNDER WHICH THE ARMY AGREED TO TRANSFER TO EPA
$1,000,000 FOR USE BY THE EPA IN SELECTING, DESIGNING AND IMPLEMENTING RESPONSE MEASURES NECESSARY TO ABATE,
MINIMIZE, STABILIZE, MITIGATE OR ELIMINATE THE THREAT OR POTENTIAL THREAT POSED TO THE PUBLIC HEALTH OR
WELFARE BY THE PRESENCE OF TCE IN SOUTH ADAMS COUNTY DRINKING WATER. EPA IS USING THE ARMY MONEY PURSUANT TO
ITS AGREEMENT WITH THE ARMY TO PAY FOR THE LEASING OF GRANULAR ACTIVATED CARBON FILTERS FOR THE TEMPORARY
TREATMENT OF WELL WATER AT SACWSD WELL SITES LOCATED AT 77TH AND QUEBEC, 77TH AND PONTIAC, AND 64TH AND
QUEBEC. THE TREATMENT SYSTEM COMMENCED OPERATION IN MAY 1986. THE CURRENT LEASED SYSTEM IS A TEMPORARY
TREATMENT METHOD. THE LEASED EQUIPMENT WILL HAVE TO BE REPLACED WITH A PERMANENT SYSTEM. THE CURRENT SYSTEM
IS LEASED, IS SIZED TO TREAT ONLY A PORTION OF THE CURRENT MAXIMUM DAY FLOW OF 12 MGD, AND IS NOT COST
EFFECTIVE OVER A 30-YEAR PLANT OPERATION PERIOD.

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IN ADDITION TO ADDRESSING THE PUBLIC WATER SUPPLY SYSTEM THROUGH INSTALLATION OF THE TEMPORARY SYSTEM, EPA
CONNECTED PRIVATE WELLS IN AREAS OF SOUTH ADAMS COUNTY WITH CONTAMINATED GROUND WATER TO THE SACWSD PUBLIC
SYSTEM PURSUANT TO EPA'S REMOVAL AUTHORITY.

DURING THE COURSE OF THE REMEDIAL INVESTIGATION, EPA DETERMINED, IN ACCORDANCE WITH 40 CFR 300.68(C), THAT AN
OPERABLE UNIT SHOULD BE CONDUCTED TO ADDRESS REPLACEMENT OR TREATMENT OF CONTAMINATED GROUND WATER PRIOR TO
ITS USE AS DRINKING WATER TO ASSURE CONTINUED PROTECTION OF THE PUBLIC HEALTH. THE OPERABLE UNIT APPROACH IS
COST EFFECTIVE AND CONSISTENT WITH THE FINAL REMEDY.

THIS OPERABLE UNIT ADDRESSES TREATMENT OR REPLACEMENT OF CONTAMINATED GROUND WATER WITHIN THE EPA OFF-POST
RI/FS SITE PRIOR TO ITS USE AS DRINKING WATER BY CUSTOMERS OF THE SACWSD. EPA IS CURRENTLY PLANNING FIELD
STUDIES FOR SUBSEQUENT OPERABLE UNITS WHICH WILL ADDRESS RESPONSE ACTIONS NECESSARY TO PROTECT HUMAN HEALTH
AND THE ENVIRONMENT. THESE RESPONSE ACTIONS MAY INCLUDE AQUIFER RESTORATION AND SOURCE CONTROL MEASURES.

#css
CURRENT SITE STATUS

GROUND WATER SAMPLING RESULTS COLLECTED FROM THE VARIOUS AREAS OF INVESTIGATION THROUGH AUGUST 1986, INDICATE
THE PRESENCE OF LARGE AREAS OF CONTAMINATED GROUND WATER WITHIN THE EPA RI/FS OFF-POST STUDY AREA BOUNDARIES.
CONTAMINATION LEVELS ARE HIGHEST IN THE AREA EAST OF HOLLY STREET. VOLATILE ORGANIC COMPOUNDS ARE PRESENT IN
THE HIGHEST CONCENTRATIONS AND ARE MOST WIDESPREAD THROUGHOUT THE SAMPLED AREA. SIX VOLATILE ORGANIC
COMPOUNDS ARE DETECTED CONSISTENTLY IN GROUND WATER SAMPLES. THESE COMPOUNDS ARE 1,1-DICHLOROETHANE (DCA) ,
1,1-DICHLOROETHENE (DCE) , TRANS 1,2-DICHLOROETHANE (TRANS-DCE) , 1,1,1-TRICHLOROETHANE (TCA) ,
TRICHLOROETHYLENE (TCE) AND TETRACHLOROETHENE (PCE). WHILE THESE COMPOUNDS EACH VARY IN LEVELS OF
CONCENTRATION AND EXTENT, THEY ARE ALL FOUND IN DETECTABLE CONCENTRATIONS BETWEEN HOLLY AND QUEBEC STREETS IN
THE STUDY AREA AND BETWEEN 56TH AND 80TH AVENUES. SAMPLES COLLECTED FROM THE SACWSD MUNICIPAL WELLS IN THIS
ZONE ALSO SHOW DETECTABLE CONTAMINATION FROM VOLATILE ORGANIC COMPOUNDS. THE RECENT HIGHEST MEASURED
CONCENTRATIONS OF VOCS WITHIN THE STUDY AREA AS SHOWN IN TABLE 1.

OTHER COMPOUNDS DETECTED IN AREAS POTENTIALLY UPGRADIENT OF THE SAC ALLUVIAL PRODUCTION WELLS INCLUDE
BENZENE, VINYL CHLORIDE, PESTICIDES, AND OTHER NON-VOLATILE ORGANIC COMPOUNDS. SEVERAL UPGRADIENT POTENTIAL
SOURCE AREAS BOTH ON AND OFF THE ARSENAL HAVE YET TO BE CHARACTERIZED. THESE POTENTIAL SOURCES ARE BEING
STUDIED BY EPA AND THE ARMY.

CONCENTRATION PLOTS OF THESE SIX VOCS, BASED ON RECENT GROUND WATER SAMPLING DATA, ARE PROVIDED AS FIGURES
5-24 THROUGH 5-29 OF THE REMEDIAL INVESTIGATION. THE PRESENCE OF OTHER IDENTIFIED VOLATILE AND NON-VOLATILE
ORGANIC COMPOUNDS AND PESTICIDES IS SHOWN ON FIGURES 5-30 THROUGH 5-34 OF THE REMEDIAL INVESTIGATION.

TABLE 2 SHOWS A REFERENCE LIST OF ALL OTHER COMPOUNDS TENTATIVELY IDENTIFIED TO DATE IN PRIVATE WELLS WITHIN
THE OFF-POST RI/FS STUDY AREA. SAMPLING DATA FOR THE SACWSD SUPPLY WELLS FOR THE PERIOD NOVEMBER 1985 TO MAY
1986, IS LISTED IN TABLE 3. TWO OF THE COMPOUNDS, DCE AND TCE, EXCEED THE FEDERAL SDWA MCLS FOR PRESENCE OF
VOCS IN DRINKING WATER.

HIGHER CONCENTRATIONS THAN THOSE SHOWN IN TABLE 1 FOR A NUMBER OF ORGANIC SOLVENTS, HAVE BEEN IDENTIFIED IN
AREAS ADJACENT TO AND UPGRADIENT OF THE CURRENT STUDY AREA. MONITORING FOR GROUND WATER CONTAMINANTS IS
CONTINUING.

PEOPLE MAY BE EXPOSED TO VOLATILE ORGANIC CONTAMINANTS PRESENT IN WATER WHILE USING THE WATER FOR DRINKING,
BATHING, COOKING, CLEANING, IRRIGATION, AND OTHER ROUTINE DOMESTIC ACTIVITIES. EXPOSURE MAY BE THROUGH
INGESTION, INHALATION, OR DERMAL CONTACT. A PRELIMINARY EVALUATION (CLEMENT ASSOCIATES, INC. APRIL 17, 1986)
INDICATED THAT THE POTENTIAL INCREMENTAL HEALTH RISKS ASSOCIATED WITH DIRECT INGESTION OF WATER AND
INHALATION OF VOLATILIZED CONTAMINANTS WHILE SHOWERING ARE REASONABLY QUANTIFIABLE AND OUTWEIGH THE RISKS
ASSOCIATED WITH OTHER POTENTIAL EXPOSURE PATHWAYS. ADDITIONALLY, ESTIMATION OF POTENTIAL EXPOSURE BY DIRECT
INGESTION OF WATER AND INHALATION DURING SHOWERING WOULD PROVIDE A REASONABLE ORDER-OF-MAGNITUDE ESTIMATE OF
RISK FROM EXPOSURE BY ALL ROUTES. THEREFORE, ONLY EXPOSURE BY THESE TWO PATHWAYS WAS CONSIDERED IN THE
ENDANGERMENT ASSESSMENT FOR THIS OPERABLE UNIT (REMEDIAL INVESTIGATION REPORT, SECTION 6.0).

CARCINOGENICITY POTENCY FACTORS WERE USED TO ESTIMATE THE POTENTIAL EXCESS CANCER RISKS ASSOCIATED WITH
EXPOSURE TO THE CONTAMINANTS OF CONCERN LISTED IN TABLE 1.

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THE USE OF SACWSD WATER DURING TWO EXPOSURE PERIODS WAS CONSIDERED IN THE PUBLIC HEALTH ENDANGERMENT
ASSESSMENT: (1) THE 1- TO 2-YEAR PERIOD NEEDED TO COMPLETE THE RI/FS AND FOLLOW-UP ACTIVITIES FOR THE SACWSD
SYSTEM 1, AND (2) LIFETIME PERIOD. THE TOTAL EXCESS CANCER RISKS ASSOCIATED WITH EXPOSURE BY INGESTION AND
INHALATION TO 1,1-DICHLOROETHYLENE, TETRACHLOROETHYLENE, AND TRICHLOROETHYLENE IN WATER FROM SACWSD WELLS ARE
SHOWN IN TABLE 4. THE RISKS ASSOCIATED WITH 2-YEAR EXPOSURE AT THE MINIMUM AND MEAN CONCENTRATIONS
CONSIDERED BY EITHER INGESTION OR INHALATION, AND THE TOTAL RISK FOR CONCURRENT EXPOSURE BY BOTH ROUTES ARE
LESS THAN 10-6. AT MAXIMUM EXPOSURE CONCENTRATIONS, THE RISKS FOR 2-YEAR EXPOSURE BY EITHER INGESTION OR
INHALATION OR FOR CONCURRENT EXPOSURE BY BOTH ROUTES EQUAL OR EXCEED 10-6. THE ADDITIVE EXCESS CANCER RISKS
ASSOCIATED WITH LIFETIME EXPOSURE TO CONTAMINANTS IN SACWSD WELLS BY INGESTION AND INHALATION RANGES FROM
10-6 TO 10-4 FOR THE THREE EXPOSURE LEVELS CONSIDERED.

THE PATHWAY OF CONCERN FOR THIS OPERABLE UNIT IS THAT WHICH IS TRANSPORTING THE CONTAMINANTS FROM SOURCES TO
THE RECEPTORS. THE PRINCIPAL MIGRATION PATHWAY FOR ORGANIC CONTAMINANTS IS THE GROUND WATER WITHIN THE
ALLUVIAL AQUIFER THAT UNDERLIES THE SITE. THIS AQUIFER IS THE PRIMARY DRINKING WATER SOURCE FOR
APPROXIMATELY 30,000 AREA RESIDENTS VIA SEVERAL SACWSD MUNICIPAL WELLS. A SIGNIFICANT PLUME OF ORGANIC
CONTAMINATION HAS BEEN DOCUMENTED TO EXTEND UP TO 4 MILES UPGRADIENT FROM THE MUNICIPAL WELLS IN THE AREA OF
77TH AND QUEBEC.

#ENF
ENFORCEMENT ANALYSIS

ON MARCH 20, 1986, EPA ENTERED INTO AN AGREEMENT WITH THE UNITED STATES DEPARTMENT OF THE ARMY FOR THE
PURPOSE OF TRANSFERRING $1 MILLION FROM THE ARMY TO EPA FOR USE IN THE SELECTION, DESIGN, AND IMPLEMENTATION
OF TREATMENT SYSTEMS OR OTHER COST-EFFECTIVE RESPONSE MEASURES NECESSARY TO ABATE, MINIMIZE, STABILIZE,
MITIGATE, OR ELIMINATE THE THREAT OR POTENTIAL THREAT POSED TO THE PUBLIC HEALTH OR WELFARE BY THE PRESENCE
OF TCE CONTAMINATION IN SOUTH ADAMS COUNTY DRINKING WATER. THE AGREEMENT STATES THAT THE ARMY WAS ONE OF TWO
OR MORE SOURCES OR POTENTIAL SOURCES OF TCE CONTAMINATION OF DRINKING WATER SUPPLIES IN SOUTH ADAMS COUNTY
AND PROVIDED FOR EPA REIMBURSEMENT OF THE ARMY IN THE EVENT THAT EPA DETERMINES THAT SOURCES OTHER THAN THE
ARMY ARE RESPONSIBLE FOR TCE CONTAMINATION AND LIABILITY MAY BE APPROXIMATELY AND REASONABLY APPORTIONED TO
THESE OTHER SOURCES. THE AGREEMENT ALSO PROVIDED THAT EPA MAY ENTER INTO COOPERATIVE AGREEMENTS PURSUANT TO
SECTION 104(D) OF CERCLA WITH THE STATE OF COLORADO OR POLITICAL SUBDIVISIONS THEREOF TO PERFORM THE WORK
CALLED FOR UNDER THE AGREEMENT.

ON APRIL 4, 1986, EPA AUTHORIZED THE LEASING AND INSTALLATION OF A TEMPORARY GAG TREATMENT SYSTEM PURSUANT TO
ITS REMOVAL AUTHORITY. EPA ENTERED INTO A COOPERATIVE AGREEMENT ON APRIL 7, 1986 IN THE AMOUNT OF $500,000
WITH THE SACWSD AND THE STATE OF COLORADO FOR THE LEASING, INSTALLATION, AND OPERATION OF MOBILE GAG FILTERS.
THE COOPERATIVE AGREEMENT WAS AMENDED ON MAY 19, 1986 TO PROVIDE AN ADDITIONAL $500,000. ARMY FUNDS
TRANSFERRED TO EPA UNDER THE MARCH 20, 1986 COOPERATIVE AGREEMENT WERE USED TO FUND THE REMOVAL ACTION UNDER
THE COOPERATIVE AGREEMENT.

ON SEPTEMBER 28, 1986, THE ARMY PROVIDED EPA WITH AN ADDITIONAL $6 MILLION PURSUANT TO AN AMENDMENT TO THE
MARCH 20, 1986, AGREEMENT FOR THE SAME PURPOSES AS PROVIDED FOR UNDER THE MARCH 20, AGREEMENT. TO DATE,
OTHER RESPONSIBLE PARTIES FOR THE TCE AND OTHER HAZARDOUS SUBSTANCE CONTAMINATION OF THE SOUTH ADAMS COUNTY
DRINKING WATER SUPPLY HAVE NOT BEEN POSITIVELY IDENTIFIED. IN THE EVENT SUCH PARTIES ARE IDENTIFIED, EPA MAY
SEEK TO RECOVER ITS RESPONSE COSTS FROM SUCH PARTIES PURSUANT TO SECTION 107 OF CERCLA AND TO REQUIRE THE
PRPS TO UNDERTAKE ANY ADDITIONAL RESPONSE ACTION AT THE SITE TO THE EXTENT PROVIDED FOR BY CERCLA, RCRA, OR
OTHER RELEVANT AUTHORITY. EPA MAY ALSO SEEK ADDITIONAL FUNDING FROM THE ARMY.

#AE
ALTERNATIVES EVALUATION

THE FS EVALUATED ALTERNATIVES SUITABLE TO ABATE THE THREAT POSED BY HAZARDOUS SUBSTANCES, POLLUTANTS, OR
CONTAMINANTS IN SACWSD DRINKING WATER. INDIVIDUALS EXPOSED OVER A LIFETIME TO THE HIGHEST LEVELS OF
CONTAMINATION IN THE GROUND WATER THROUGH INGESTION OR INHALATION HAVE AN EXCESS RISK OF CANCER OF 1 X 10-4
TO 2 X 10-6. THE REMEDIAL ALTERNATIVES EVALUATED FOR THIS OPERABLE UNIT HAVE THE OBJECTIVE OF MINIMIZING OR
ELIMINATING EXPOSURE TO THE CONTAMINANTS PRESENT IN THE CONTAMINATED GROUND WATER USED AS A DRINKING WATER
SOURCE BY THE SACWSD IN ORDER TO ASSURE PROTECTION OF PUBLIC HEALTH. FUTURE OPERABLE UNITS WILL ADDRESS
SOURCE CONTROL MEASURES, AND/OR CLEANUP OF THE GROUND WATER.
1. EPA INSTALLED A TEMPORARY TREATMENT SYSTEM IN MAY 1986 WHICH IS PROVIDING SAFE DRINKING WATER AT
LEVELS BELOW THE SDWA MCLS.

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IN ACCORDANCE WITH SECTION 300.68(F) OF THE NCP, EPA DEVELOPED THE FOLLOWING CATEGORIES:

CATEGORY DESCRIPTION

1 ALTERNATIVES FOR TREATMENT OR DISPOSAL AT AN OFF-SITE FACILITY.

2 ALTERNATIVES WHICH ATTAIN APPLICABLE OR RELEVANT AND
APPROPRIATE PUBLIC HEALTH OR ENVIRONMENTAL STANDARDS.

3 ALTERNATIVES WHICH EXCEED APPLICABLE OR RELEVANT AND
APPROPRIATE PUBLIC HEALTH OR ENVIRONMENTAL STANDARDS.

4 ALTERNATIVES WHICH DO NOT ATTAIN APPLICABLE OR RELEVANT
AND APPROPRIATE PUBLIC HEALTH OR ENVIRONMENTAL STANDARDS
BUT WILL REDUCE THE LIKELIHOOD OF PRESENT OR FUTURE THREAT
FROM THE HAZARDOUS SUBSTANCES AND WHICH PROVIDE
SIGNIFICANT PROTECTION TO PUBLIC HEALTH, WELFARE, AND THE
ENVIRONMENT. THIS MUST INCLUDE AN ALTERNATIVE WHICH MOST
CLOSELY APPROACHES THE LEVEL OF PROTECTION PROVIDED BY THE
APPLICABLE OR RELEVANT STANDARDS.

5 NO ACTION ALTERNATIVE.

THE ALTERNATIVES SCREENED ARE:

ALTERNATIVE CATEGORY

1. NO ACTION 5

2. ALTERNATE WATER SUPPLY 2,3

3. AIR STRIPPING OF VOLATILE ORGANIC COMPOUNDS 2,3

4. AIR STRIPPING OF POTENTIAL SEMI-VOLATILE ORGANIC COMPOUNDS 2,3

5. AIR STRIPPING OF VOLATILE ORGANIC COMPOUNDS WITH
OFF-GAS TREATMENT 2,3

6. AIR STRIPPING OF POTENTIAL SEMI-VOLATILE ORGANIC COMPOUNDS
WITH OFF-GAS TREATMENT 2,3

7. GRANULAR ACTIVATED CARBON (GAG) 2,3

8. AIR STRIPPING WITH OFF-GAS TREATMENT FOR WELLS 14 AND 16.
GAG FOR WELLS 2, 3, 5, 15, AND 17 2,3

9. CONTINUED USE OF GAG SYSTEM LEASED FOR REMOVAL ACTION 2,3

10. BLENDING 4.

IN ADDITION, ALTERNATIVES 5-9 PROVIDE A RANGE OF TREATMENT ALTERNATIVES WHICH PERMANENTLY AND SIGNIFICANTLY,
IN WHOLE OR IN PART, REDUCE THE TOXICITY, VOLUME OR MOBILITY OF THE HAZARDOUS SUBSTANCES, POLLUTANTS OR
CONTAMINANTS IDENTIFIED IN SACWSD DRINKING WATER SUPPLY WELLS TO DATE.

THE RI/FS FOR THIS OPERABLE UNIT WAS INITIATED ON OCTOBER 2, 1985, PRIOR TO THE ENACTMENT OF SARA. IN
ACCORDANCE WITH CURRENT EPA POLICY AT THE TIME OF COMMENCEMENT OF THE RI/FS, THE REGION CONSIDERED MAXIMUM
CONTAMINANT LEVELS (MCLS) ESTABLISHED UNDER THE SAFE DRINKING WATER ACT (SDWA) AS THE APPLICABLE OR RELEVANT
AND APPROPRIATE REQUIREMENTS ("ARARS") FOR THIS OPERABLE UNIT. SEE "CERCLA COMPLIANCE WITH OTHER
ENVIRONMENTAL STATUTES," 50 FED. REG. 47946, 47949 (NOV. 29, 1985) (MCLS INCLUDED IN LIST OF POTENTIAL ARARS;
MCLGS (FORMERLY RMCLS) INCLUDED IN LIST OF OTHER REQUIREMENTS TO BE CONSIDERED).

EPA DEVELOPED ALTERNATIVES TO ATTAIN OR EXCEED MCLS, THE ARARS FOR THIS OPERABLE UNIT BEFORE SARA. THE TABLE
ABOVE REFLECTS THIS APPROACH, I.E., ALTERNATIVES THAT ATTAIN OR EXCEED ARARS ARE ALTERNATIVES THAT ATTAIN OR
EXCEED MCLS. ALL OF THE ALTERNATIVES, WITH THE EXCEPTION OF BLENDING AND NO ACTION WILL ATTAIN OR EXCEED
MCLS.

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AFTER THE ENACTMENT OF SARA, EPA IDENTIFIED A RANGE OF ARARS FOR PUBLIC COMMENT IN THE FS, WHICH INCLUDED
MCLS, MCLGS, AND WATER QUALITY CRITERIA. SEE CONSISTENCY WITH OTHER ENVIRONMENTAL REQUIREMENTS, PP. 26. EPA
HAS DETERMINED THAT THE APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS FOR THIS OPERABLE UNIT ARE THE
MAXIMUM CONTAMINANT LEVELS ("MCLS") ESTABLISHED UNDER THE SAFE DRINKING WATER ACT ("SDWA") FOR HAZARDOUS
SUBSTANCES, POLLUTANTS, OR CONTAMINANTS IDENTIFIED IN SOUTH ADAMS COUNTY DRINKING WATER. UNDER THE SDWA,
CONGRESS ESTABLISHED A TWO-PRONGED APPROACH FOR DETERMINING PERMISSIBLE LEVELS OF CONTAMINANTS IN WATER WHICH
IS DELIVERED TO ANY USER OF A PUBLIC WATER SYSTEM: (1) MAXIMUM CONTAMINANT LEVEL GOALS ("MCLGS") ARE TO BE
SET AT THE LEVEL AT WHICH NO KNOWN OR ANTICIPATED ADVERSE EFFECTS ON HEALTH OF PERSONS OCCUR AND WHICH ALLOWS
AN ADEQUATE MARGIN OF SAFETY; AND (2) MCLS ARE TO BE SET AS CLOSE TO THE MCLG AS IS FEASIBLE. SECTION
1412 (B) (4) OF THE SDWA. MCLGS ARE NON-ENFORCEABLE HEALTH GOALS. MCLS ARE ENFORCEABLE REQUIREMENTS WHICH
SPECIFY THE MAXIMUM PERMISSIBLE LEVEL OF A CONTAMINANT IN WATER WHICH IS DELIVERED TO ANY USER OF A PUBLIC
WATER SYSTEM. SECTION 1401(3) OF THE SDWA.

CONGRESS DEFINED THE TERM FEASIBLE TO MEAN:

... WITH THE USE OF THE BEST TECHNOLOGY, TREATMENT TECHNIQUES, AND OTHER MEANS WHICH THE ADMINISTRATOR
FINDS, AFTER EXAMINATION FOR EFFICACY UNDER FIELD CONDITIONS AND NOT UNDER LABORATORY CONDITIONS, ARE
AVAILABLE (TAKING COST INTO CONSIDERATION) ... GRANULAR ACTIVATED CARBON IS FEASIBLE FOR THE CONTROL
OF SYNTHETIC ORGANIC CHEMICALS, AND ANY TECHNOLOGY, TREATMENT TECHNIQUE, OR OTHER MEANS FOUND TO BE
THE BEST AVAILABLE FOR THE CONTROL OF SYNTHETIC ORGANIC CHEMICALS MUST BE AT LEAST AS EFFECTIVE IN
CONTROLLING SYNTHETIC ORGANIC CHEMICALS AS GRANULAR ACTIVATED CARBON.".

SECTION 1412(B)(5) OF THE SDWA.

FOR THE ABOVE REASONS, EPA HAS SELECTED MCLS AS THE LEGALLY APPLICABLE OR RELEVANT AND APPROPRIATE
REQUIREMENT WHICH THE SELECTED REMEDY MUST AT LEAST ATTAIN FOR THIS OPERABLE UNIT. 2.

THE AGENCY EXPECTS THAT THE MCLS WILL DRIVE THE DESIGN AND OPERATION OF THE REMEDY. BY NOT EXCEEDING MCLS,
THE SELECTED REMEDY WILL ASSURE PROTECTION OF HUMAN HEALTH FOR OTHER HAZARDOUS SUBSTANCES, POLLUTANTS, OR
CONTAMINANTS IDENTIFIED IN SOUTH ADAMS COUNTY DRINKING WATER FOR WHICH MCLS HAVE NOT BEEN PROPOSED OR FINALLY
PROMULGATED. IN ANY EVENT, THE SELECTED REMEDY WILL AT LEAST ATTAIN A LEVEL OF CONTROL FOR SUCH OTHER
HAZARDOUS SUBSTANCES, POLLUTANTS, OR CONTAMINANTS THAT FALLS WITHIN A TOTAL RISK RANGE OF 10-4 TO 10-7 OVER A
70-YEAR LIFETIME EXPOSURE, WITH A GOAL OF ATTAINING A LEVEL OF CONTROL THAT REFLECTS A 10-6 RISK.
2. APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS ARE SELECTED ON SITE-SPECIFIC BASIS. THE
SELECTION OF MCLS AS THE APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENT FOR THIS OPERABLE UNIT IS
NOT INTENDED TO ESTABLISH PRECEDENT FOR REMEDIAL ACTION AT OTHER SITES OR OPERABLE UNITS, INCLUDING,
BUT NOT LIMITED TO, GROUND WATER AND SURFACE WATER RESTORATION, AND IS NOT INTENDED TO ESTABLISH
PRECEDENT FOR ANY CONTAMINANTS NOT IDENTIFIED IN SOUTH ADAMS COUNTY DRINKING WATER.

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SINCE SHIPMENT OF CONTAMINATED SOILS OR DRINKING WATER IS NOT WITHIN THE OBJECTIVE OF THIS OPERABLE UNIT,
DEVELOPMENT OF AN ALTERNATIVE FOR OFF-SITE TREATMENT OR DISPOSAL (40 CFR SECTION 300.68(F)(1)(I)) IS NOT
APPROPRIATE. HOWEVER, SPENT CARBON FROM THE GAG SYSTEM WILL ONLY BE TRANSFERRED TO A FACILITY OPERATING IN
COMPLIANCE WITH SECTIONS 3004 AND 3005 OF THE SOLID WASTE DISPOSAL ACT (SWDA) , IN ACCORDANCE WITH SECTION
121(D)(3) OF CERCLA.

A DISCUSSION OF ARARS FOR THIS OPERABLE UNIT FOLLOWS IN THE SECTION OF THIS DOCUMENT TITLED "CONSISTENCY WITH
OTHER ENVIRONMENTAL REQUIREMENTS.".

ALTERNATIVES WERE SUBJECTED TO AN INITIAL SCREENING TO NARROW THE LIST OF POTENTIAL REMEDIAL ACTIONS FOR
FURTHER DETAILED ANALYSIS USING THE CRITERIA OF COST, EFFECTIVENESS, AND ACCEPTABLE ENGINEERING PRACTICES AS
DIRECTED BY 40 CFR SECTION 300.68(G). COSTS INCLUDING OPERATION AND MAINTENANCE (O&M) WERE CONSIDERED FOR
EACH ALTERNATIVE. EACH ALTERNATIVE WAS SCREENED BY EVALUATING FEASIBILITY, APPLICABILITY, AND RELIABILITY.
EFFECTIVENESS IN PROTECTING HUMAN HEALTH WAS CONSIDERED.

DURING THE SCREENING PROCESS, THE NO ACTION ALTERNATIVE WAS ELIMINATED BASED ON EFFECTIVENESS BECAUSE IT DOES
NOT PROTECT HUMAN HEALTH. INHABITANTS WOULD CONTINUE TO REMAIN EXPOSED AT RISK LEVELS ABOVE 10-6, DUE TO VOC
CONCENTRATIONS IN DRINKING WATER.

ALTERNATIVE NO. 9 FOR USING THE LEASED GAG UNITS WAS ELIMINATED DURING THE SCREENING PROCESS BASED ON
EFFECTIVENESS, ACCEPTABLE ENGINEERING PRACTICES, AND COST BECAUSE THE UNITS ARE UNDERSIZED (EXCESSIVE HEAD
LOSS THROUGH THE FILTERS WILL NOT ALLOW THE DISTRICT TO MEET PEAK DEMANDS), ARE NOT COST EFFECTIVE FOR A
30-YEAR PLANT LIFE AND THE MANUFACTURER'S STATEMENT THAT THE UNITS ARE NOT FOR SALE. THE ALTERNATE WATER
SUPPLY ALTERNATIVE AND THE ALTERNATIVE OF AIR STRIPPING OF POTENTIAL SEMI-VOLATILE ORGANICS WITH OFF-GAS
TREATMENT WERE ELIMINATED BASED ON COST CRITERIA. THE COSTS OF THESE TWO ALTERNATIVES FAR EXCEED THE CAPITAL
AND O&M COSTS OF OTHER ALTERNATIVES EVALUATED AND DO NOT PROVIDE SUBSTANTIALLY GREATER PUBLIC HEALTH
PROTECTION.

THE BLENDING ALTERNATIVE WAS ELIMINATED BASED ON EFFECTIVENESS. TCE CONCENTRATIONS ARE TOO HIGH IN
INDIVIDUAL WELLS TO PRODUCE BLENDED WATER THAT WOULD HAVE TCE CONCENTRATIONS BELOW THE SDWA MCLS.

THE REMAINING ALTERNATIVES WERE EVALUATED IN MORE DETAIL IN ACCORDANCE WITH 40 CFR SECTION 300.68(H). EACH
ALTERNATIVE WAS EVALUATED FOR COST, EFFECTIVENESS IN ACHIEVING THE DESIRED HUMAN HEALTH PROTECTION,
IMPLEMENTABILITY OF THE ALTERNATIVES, PERMANENCY RESULTING IN A PERMANENT AND SIGNIFICANT DECREASE IN THE
TOXICITY, MOBILITY AND VOLUME OF THE HAZARDOUS SUBSTANCE, INSTITUTIONAL CONSIDERATIONS, AND ADVERSE IMPACTS.

COST

TABLE 5 CONTAINS THE ESTIMATED PRESENT VALUE COSTS OF EACH OF THE REMAINING ALTERNATIVES. THREE ALTERNATIVES
(GRANULAR ACTIVATED CARBON, AIR STRIPPING WITH OFF-GAS TREATMENT, AND AIR STRIPPING WITH OFF-GAS TREATMENT
FOR TWO WELLS AND GAG FOR FIVE WELLS) WERE COMPARABLE AT ALL THREE DISCOUNT RATES. THE OTHER TWO AIR
STRIPPING ALTERNATIVES WERE ELIMINATED BECAUSE THEY DO NOT MEET THE PREFERENCE UNDER SECTION 121 OF SARA FOR
REMEDIES WHICH PERMANENTLY AND SIGNIFICANTLY REDUCE THE MOBILITY, TOXICITY, AND VOLUME OF VOLATILE ORGANIC
COMPOUNDS.

INSTITUTIONAL CONSIDERATIONS

FUTURE USE OF GROUND WATER FROM NEW PRIVATE WELLS THAT WOULD DRAW WATER FROM THE ALLUVIUM UNDERLYING THE
STUDY AREA IS NOT EXPECTED TO MEET THE ARAR CRITERIA. THEREFORE, THE EPA MAY CONSIDER SEEKING INSTITUTIONAL
CONTROLS THAT WOULD RESTRICT FUTURE USE OF ALLUVIAL GROUND WATER UNDERLYING THE EPA OFF-POST RI/FS STUDY AREA
FOR DRINKING WATER AS A PART OF THE SECOND OPERABLE UNIT. AS PREVIOUSLY NOTED, EXISTING PRIVATE WELLS WERE
CONNECTED TO THE SACWSD SYSTEM BY EPA IN SUMMER 1986.

TECHNICAL FEASIBILITY

ENGINEERING, IMPLEMENTATION, RELIABILITY AND CONSTRUCTIBILITY WERE EVALUATED. THE TREATMENT TECHNOLOGIES ARE
ALL BASED ON PROVEN TECHNOLOGIES AND ALL HAVE A HISTORY OF ACCEPTABLE USE. ALL TREATMENT ALTERNATIVES REDUCE
THE CONCENTRATION OF VOLATILE ORGANIC COMPOUNDS TO LESS THAN THE LEVELS THAT EPA HAS DETERMINED TO BE
APPLICABLE FEDERAL AND STATE REQUIREMENTS (SEE PAGE 17) .

IN ACCORDANCE WITH SECTION 300.68(H)(2)(V) OF THE NCP, AN ANALYSIS WAS MADE OF WASTE MINIMIZATION, REUSE, AND
DESTRUCTION. UNDER THE RECOMMENDED ALTERNATIVE, THE VOCS WILL BE DESTROYED BY INCINERATION WHEN THE CARBON
IS REGENERATED.

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PUBLIC HEALTH AND ENVIRONMENTAL IMPACTS

THE RI/FS INCLUDED AN ASSESSMENT OF THE EXTENT TO WHICH EACH ALTERNATIVE WOULD EFFECTIVELY PREVENT, MITIGATE,
OR MINIMIZE THREATS TO, AND PROVIDE PROTECTION OF PUBLIC HEALTH AND AN ANALYSIS OF ADVERSE ENVIRONMENTAL
IMPACTS. THESE ARE SUMMARIZED IN TABLE 6. THE SECOND OPERABLE UNIT WILL ADDRESS WHETHER OR NOT FUTURE
RESPONSE ACTIONS ARE NECESSARY TO PROTECT PUBLIC HEALTH, WELFARE, AND THE ENVIRONMENT.

PERMANENCY

ALL THE WATER TREATMENT ALTERNATIVES EVALUATED REDUCE THE CONCENTRATIONS OF VOLATILE ORGANIC COMPOUNDS IN
DRINKING WATER TO LESS THAN THE LEVELS THAT EPA HAS DETERMINED TO BE APPLICABLE FEDERAL AND STATE
REQUIREMENTS (SEE PAGE 17). THE GAG AND AIR STRIPPING WITH OFF-GAS TREATMENT ALTERNATIVES PROVIDE A
PERMANENT TREATMENT SOLUTION BY EITHER INCINERATING AT AN APPROVED RCRA FACILITY OR RECOVERING THE VOCS. THE
AIR STRIPPING WITHOUT OFF-GAS TREATMENT ALTERNATIVES TRANSFER THE VOCS FROM THE WATER TO AIR. (THESE ARE
SUMMARIZED IN TABLE 6).

#CR
COMMUNITY RELATIONS

THE COMMUNITY RELATIONS RESPONSIVENESS SUMMARY (ATTACHED) DESCRIBES THE COMMUNITY'S NATURE AND LEVEL OF
CONCERN, AND THE RESPONSES AND CONCERNS REGARDING THE ALTERNATIVES EVALUATED IN THE FS.

#OEL
CONSISTENCY WITH OTHER ENVIRONMENTAL REQUIREMENTS

ON OCTOBER 17, 1986, THE PRESIDENT SIGNED THE SUPERFUND AMENDMENTS AND REAUTHORIZATION ACT OF 1986 (SARA).
SECTION 121(D)(1) OF SARA REQUIRES THAT SELECTED REMEDIAL ACTIONS ATTAIN A DEGREE OF CLEANUP OF HAZARDOUS
SUBSTANCES RELEASED INTO THE ENVIRONMENT AND OF CONTROL OF FURTHER RELEASE AT A MINIMUM WHICH ASSURES
PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT. SECTION 121 (D) (2) OF SARA STATES THAT REMEDIAL ACTIONS SHALL
REQUIRE A LEVEL OR STANDARD OF CONTROL WHICH AT LEAST ATTAINS LEGALLY APPLICABLE OR RELEVANT AND APPROPRIATE
STANDARDS, LIMITATIONS, CRITERIA, AND REQUIREMENTS ("REQUIREMENTS") OF FEDERAL ENVIRONMENTAL LAWS, AND
APPLICABLE OR RELEVANT AND APPROPRIATE PROMULGATED REQUIREMENTS UNDER STATE ENVIRONMENTAL OR SITING LAWS THAT
ARE MORE STRINGENT THAN FEDERAL REQUIREMENTS.

THE FEASIBILITY STUDY FOR THIS OPERABLE UNIT IDENTIFIED A RANGE OF POTENTIAL ARARS 3, INCLUDING MCLS, MCLGS,
WATER QUALITY CRITERIA ESTABLISHED UNDER THE CLEAN WATER ACT, NESHAPS FOR VINYL CHLORIDE AND NATIONAL AMBIENT
AIR QUALITY STANDARDS (NAAQS). AFTER CONSIDERATION OF PUBLIC COMMENTS, THE AGENCY HAS DETERMINED THAT THE
APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS FOR THIS OPERABLE UNIT ARE THE MAXIMUM CONTAMINANT LEVELS
("MCLS") ESTABLISHED UNDER THE SAFE DRINKING WATER ACT ("SDWA") FOR HAZARDOUS SUBSTANCES, POLLUTANTS, OR
CONTAMINANTS IDENTIFIED IN SOUTH ADAMS COUNTY DRINKING WATER. UNDER THE SDWA, CONGRESS ESTABLISHED A
TWO-PRONGED APPROACH FOR DETERMINING PERMISSIBLE LEVELS OF CONTAMINANTS IN WATER WHICH IS DELIVERED TO ANY
USER OF A PUBLIC WATER SYSTEM: (1) MAXIMUM CONTAMINANT LEVEL GOALS ("MCLGS") ARE TO BE SET AT THE LEVEL AT
WHICH NO KNOWN OR ANTICIPATED ADVERSE EFFECTS ON HEALTH OF PERSONS OCCUR AND WHICH ALLOWS AN ADEQUATE MARGIN
OF SAFETY; AND (2) MCLS ARE TO BE SET AS CLOSE TO THE MCLG AS IS FEASIBLE. SECTION 1412(B)(4) OF THE SDWA.
MCLGS ARE NON-ENFORCEABLE HEALTH GOALS. MCLS ARE ENFORCEABLE REQUIREMENTS WHICH SPECIFY THE MAXIMUM
PERMISSIBLE LEVEL OF A CONTAMINANT IN WATER WHICH IS DELIVERED TO ANY USER OF A PUBLIC WATER SYSTEM. SECTION
1401 (3) OF THE SDWA.

CONGRESS DEFINED THE TERM FEASIBLE TO MEAN:

SECTION 1412(B)(5) OF THE SDWA.
3. THE RI/FS FOR THE SITE WAS COMMENCED PRIOR TO THE ENACTMENT OF SARA. AT THE COMMENCEMENT OF THE
RI/FS, THE AGENCY HAD IDENTIFIED MAXIMUM CONTAMINANT LEVELS (MCLS) ESTABLISHED UNDER THE SAFE DRINKING
WATER ACT AS THE ARARS FOR THE SITE IN ACCORDANCE WITH CURRENT AGENCY POLICY. THE REGION IDENTIFIED A
RANGE OF ARARS FOR PUBLIC COMMENT IN THE FS, WHICH INCLUDED MCLS, MCLGS, AND WATER QUALITY CRITERIA.
ALL ALTERNATIVES EVALUATED IN THE FS, WITH THE EXCEPTION OF THE NO ACTION AND BLENDING ALTERNATIVES,
WOULD REDUCE THE CONCENTRATION OF VOLATILE ORGANIC COMPOUNDS TO LESS THAN THE LEVELS THAT EPA HAS
DETERMINED TO BE APPLICABLE FEDERAL AND STATE REQUIREMENTS (SEE PAGE 17).

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THE SELECTED REMEDIAL ACTION FOR THIS OPERABLE UNIT IS A GRANULAR ACTIVATED CARBON TREATMENT SYSTEM. IN
SELECTING GAG, EPA IS UTILIZING A TECHNOLOGY WHICH CONGRESS EXPLICITLY RECOGNIZED AS FEASIBLE UNDER THE SAFE
DRINKING WATER ACT. ID. MOREOVER, BY SPECIFYING MCLS AS THE APPLICABLE OR RELEVANT AND APPROPRIATE
REQUIREMENT THAT CANNOT BE EXCEEDED FOR THIS OPERABLE UNIT, EPA IS IMPLEMENTING AND ACTING CONSISTENTLY WITH
THE STATUTORILY MANDATED PROCESS AND CRITERIA THAT CONGRESS PRESCRIBED FOR ALL PUBLIC DRINKING WATER SYSTEMS
NATIONWIDE. IN ADDITION, THE MCLS SELECTED AS APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS FOR THIS
OPERABLE UNIT FOR CONTAMINANTS IDENTIFIED IN SOUTH ADAMS COUNTY DRINKING WATER ASSURE ADEQUATE PROTECTION OF
HUMAN HEALTH.

FOR THE ABOVE REASONS, EPA HAS SELECTED MCLS AS THE LEGALLY APPLICABLE OR RELEVANT AND APPROPRIATE
REQUIREMENT WHICH THE SELECTED REMEDY MUST AT LEAST ATTAIN FOR THIS OPERABLE UNIT. 4

NESHAPS FOR VINYL CHLORIDE AND BENZENE ARE RELEVANT AND APPROPRIATE IN THE EVENT AIR STRIPPING IS NEEDED TO
TREAT VINYL CHLORIDE (40 CFR PART 61, SUBPARTS F AND J).

THE STATE OF COLORADO PROVIDED EPA WITH A LIST OF APPLICABLE OR RELEVANT AND APPROPRIATE STATE STANDARDS,
REQUIREMENTS, LIMITATIONS, OR CRITERIA ("STATE REQUIREMENTS") FOR THIS OPERABLE UNIT ON JANUARY 8, 1987. THE
STATE AMENDED ITS LIST ON MARCH 17, 1987 TO DELETE SEVERAL REQUIREMENTS AND ADD AN ADDITIONAL REQUIREMENT.
EPA HAS REVIEWED THE PROPOSED STATE REQUIREMENTS UNDER THE CRITERIA SET FORTH IN SECTION 121 (D) OF CERCLA,
AND DETERMINED THAT CERTAIN PROVISIONS WITHIN THE FOLLOWING STATE REQUIREMENTS GENERALLY ARE APPLICABLE OR
RELEVANT AND APPROPRIATE:
4. APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS ARE SELECTED ON A SITE-SPECIFIC BASIS. THE
SELECTION OF MCLS AS THE APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENT FOR THIS OPERABLE UNIT IS
NOT INTENDED TO ESTABLISH PRECEDENT FOR REMEDIAL ACTION AT OTHER SITES OR OPERABLE UNITS, INCLUDING,
BUT NOT LIMITED TO, GROUND WATER AND SURFACE WATER RESTORATION, AND IS NOT INTENDED TO ESTABLISH
PRECEDENT FOR ANY CONTAMINANTS NOT IDENTIFIED IN SOUTH ADAMS COUNTY DRINKING WATER.

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1. THE COLORADO HAZARDOUS WASTE ACT AND REGULATIONS

APPLICABLE TO THE EXTENT THE SELECTED REMEDY INVOLVES THE GENERATION, TRANSPORTATION, TREATMENT,
OR STORAGE OF HAZARDOUS WASTE IN THE SPENT GRANULAR ACTIVATED CARBON. THE SELECTED REMEDY DOES
NOT CONTEMPLATE DISPOSAL OF HAZARDOUS WASTE.

2. THE COLORADO PRIMARY DRINKING WATER REGULATIONS

3. THE COLORADO AIR QUALITY CONTROL REGULATIONS

4. THE COLORADO NOISE ABATEMENT STATUTE

APPLICABLE OR RELEVANT AND APPROPRIATE TO ESTABLISH MAXIMUM PERMISSIBLE NOISE LEVELS FOR
CONSTRUCTION OR OPERATION OF THE SELECTED REMEDY.

5. THE COLORADO WILDLIFE STATUTES AND REGULATIONS

6. THE WATER WELL AND PUMP INSTALLATION CONTRACTOR ACT AND REGULATIONS

APPLICABLE OR RELEVANT AND APPROPRIATE TO PUMP INSTALLATION. THE SELECTED REMEDY DOES NOT
CONTEMPLATE THE CONSTRUCTION OF WATER WELLS.

7. HISTORICAL, PREHISTORICAL, AND ARCHAEOLOGICAL RESOURCES ACT

APPLICABLE OR RELEVANT AND APPROPRIATE IF THE SELECTED REMEDY INVOLVES THE INVESTIGATION,
EXCAVATION, GATHERING, OR REMOVAL FROM THE NATURAL STATE OF ANY HISTORICAL, PREHISTORICAL, AND
ARCHAEOLOGICAL RESOURCES WITHIN THE STATE. THE SELECTED REMEDY DOES NOT CONTEMPLATE ANY OF THESE
ACTIVITIES.

8. THE COLORADO WATER QUALITY CONTROL ACT AND REGULATIONS

APPLICABLE OR RELEVANT AND APPROPRIATE TO THE EXTENT THE SELECTED REMEDY INVOLVES THE DISCHARGE
OF POLLUTANTS TO WATERS OF THE STATE OF COLORADO. THE SELECTED REMEDY DOES NOT CONTEMPLATE SUCH
A DISCHARGE.

#RA
RECOMMENDED ALTERNATIVE

THE REMEDY RECOMMENDED IS A GRANULAR ACTIVATED CARBON TREATMENT SYSTEM AND REGENERATION OF SPENT CARBON. THE
RECOMMENDED ALTERNATIVE IS A COST EFFECTIVE REMEDIAL ALTERNATIVE THAT EFFECTIVELY MITIGATES AND MINIMIZES
THREATS TO AND PROVIDES ADEQUATE PROTECTION OF PUBLIC HEALTH. COST, TECHNOLOGY, RELIABILITY, AND PERMANENCY,
AND THE EFFECT ON THE PUBLIC HEALTH WERE EVALUATED IN SELECTING THIS ALTERNATIVE FROM AMONG THOSE THAT
PROVIDE ADEQUATE PROTECTION OF PUBLIC HEALTH.

THE GAG SYSTEM WILL TREAT CONTAMINATED WATER FROM THE SOUTH ADAMS COUNTY WATER AND SANITATION DISTRICT
(SACWSD) DRINKING WATER SUPPLY WELLS PRIOR TO ITS CONSUMPTION AS DRINKING WATER. THE GAG SYSTEM WILL REMOVE
THE HAZARDOUS SUBSTANCES OF PRIMARY CONCERN FROM THE DRINKING WATER TO LEVELS WHICH WILL ASSURE PROTECTION OF
HUMAN HEALTH AND ATTAIN APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS. IN THE EVENT THAT OTHER
VOLATILE, SEMI-VOLATILE, AND NON-VOLATILE ORGANIC COMPOUNDS ARE IDENTIFIED IN GROUND WATER SUPPLYING THE
SACWSD WELLS, THE GAG SYSTEM WILL TREAT SUCH HAZARDOUS SUBSTANCES TO A LEVEL THAT WILL ASSURE PROTECTION OF
HUMAN HEALTH WITHOUT MODIFICATION AND ATTAIN APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS.

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THE GAG SYSTEM MAY NOT TREAT VINYL CHLORIDE TO ACCEPTABLE LEVELS; THEREFORE, THE SYSTEM WILL BE DESIGNED SO
THAT AN AIR STRIPPING FACILITY CAN BE ADDED TO TREAT VINYL CHLORIDE IN THE EVENT THAT VINYL CHLORIDE DETECTED
UPGRADIENT OF THE SACWSD SUPPLY WELLS POSES A THREAT TO THE SACWSD AND PUBLIC HEALTH. EPA WILL CONTINUE TO
MONITOR PERIODICALLY FOR VINYL CHLORIDE TO DETERMINE WHETHER IT PRESENTS A THREAT TO PUBLIC HEALTH.

ADDITIONALLY, IN ORDER TO ASSURE THAT THE REMEDY OPERATES EFFECTIVELY AND PROVIDES ADEQUATE SAFE DRINKING
WATER SUPPLIES FOR THE ESTIMATED SACWSD WATER DEMAND OF 12.0 MGD, THE REMEDY CONSISTS OF THE REPLACEMENT OF
EXISTING WELL PUMPS AND MOTORS, THE INSTALLATION OF TRANSMISSION PIPING, AND THE CONSTRUCTION OF LABORATORY
AND OFFICE SPACE NECESSARY TO OPERATE AND ANALYZE THIS 12.0 MGD SYSTEM.

SPENT CARBON FROM THE GAG TREATMENT SYSTEM WILL BE REGENERATED AT AN INCINERATOR IN COMPLIANCE WITH SECTIONS
3004 AND 3005 OF SWDA, IN ACCORDANCE WITH SECTION 121(D) (3) OF CERCLA. THE CURRENTLY ESTIMATED CAPITAL COSTS
FOR THE GAG SYSTEM ARE $8,869,000 (TABLE 7). IF AN AIR STRIPPER TO TREAT VINYL CHLORIDE IS REQUIRED, THE
TOTAL CAPITAL COSTS WOULD BE INCREASED BY $1,231,000 (TABLE 7).

TO ASSURE PROTECTION OF THE PUBLIC HEALTH IN THE INTERIM PERIOD BETWEEN APPROVAL OF THE RECORD OF DECISION
AND COMPLETION AND OPERATION OF THE SELECTED REMEDY, THE TEMPORARY GAG TREATMENT SYSTEM, INSTALLED IN JUNE
1986 UNDER EPA'S REMOVAL AUTHORITY TO TREAT SACWSD DRINKING WATER WILL CONTINUE TO BE LEASED AND OPERATED AND
DEMOBILIZED, UNTIL THE PERMANENT SYSTEM IS ON LINE. THE TEMPORARY SYSTEM IS DESIGNED TO TREAT CONTAMINATED
GROUND WATER TO LEVELS AT OR BELOW MAXIMUM CONTAMINANT LEVELS ESTABLISHED UNDER THE SAFE DRINKING WATER ACT.
THE CURRENTLY ESTIMATED OPERATION AND MAINTENANCE COSTS FOR THIS TEMPORARY GAG TREATMENT SYSTEM ARE
331,000/MONTH (TABLE 7).

THE LEAST COSTLY ALTERNATIVE, AIR STRIPPING WITHOUT OFF-GAS TREATMENT, ONLY TRANSFERS THE VOLATILE ORGANIC
COMPOUNDS FROM A WATER MEDIA TO THE ATMOSPHERE AND DOES NOT RESULT IN A PERMANENT AND SIGNIFICANT DECREASE IN
THE TOXICITY, MOBILITY, AND VOLUME OF THE HAZARDOUS SUBSTANCES AND WAS, THEREFORE, REJECTED. THIS
ALTERNATIVE DOES NOT ACHIEVE THE PREFERENCE OF CERCLA SECTION 121 (B) FOR PERMANENT REMEDIES, AND WAS
THEREFORE REJECTED.

THE AIR STRIPPING WITH OFF-GAS TREATMENT ALTERNATIVES RANKED EQUALLY WITH THE GAG ALTERNATIVE IN TERMS OF
COST, ABILITY TO PROTECT PUBLIC HEALTH, TECHNICAL FEASIBILITY, ENVIRONMENTAL IMPACTS, AND TREATMENT WHICH
PERMANENTLY AND SIGNIFICANTLY REDUCES THE MOBILITY, TOXICITY, AND VOLUME OF VOLATILE ORGANIC COMPOUNDS.
HOWEVER, THE GAG ALTERNATIVE IS RECOMMENDED OVER AIR STRIPPING WITH OFF-GAS TREATMENT. IN THE EVENT THAT
OTHER VOLATILE, SEMI-VOLATILE, AND/OR NON VOLATILE ORGANIC COMPOUNDS ARE IDENTIFIED IN GROUND WATER SUPPLYING
THE SACWSD WELLS, THE GAG SYSTEM WILL HAVE THE GREATEST CAPABILITY OF THE TREATMENT ALTERNATIVES EVALUATED TO
TREAT A WIDE SPECTRUM OF SUCH HAZARDOUS SUBSTANCES TO A LEVEL THAT WILL ASSURE PROTECTION OF HUMAN HEALTH,
WITHOUT MODIFICATION. CAPITAL COSTS FOR THE RECOMMENDED ALTERNATIVE ARE LISTED IN TABLE 7.

THE STATE OF COLORADO AND THE SACWSD HAVE BEEN CONSULTED AND CONCUR WITH THE SELECTED REMEDY (APPENDIX C).

THE ACTION WILL REQUIRE FUTURE OPERATION AND MAINTENANCE ACTIVITIES TO ASSURE THE CONTINUED EFFECTIVENESS OF
THE REMEDY. O&M ACTIVITIES INCLUDE ELECTRIC POWER, CHEMICALS, MAINTENANCE, REPAIR, AND LABOR. O&M COSTS ARE
SHOWN ON TABLE 8.

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#SCH
SCHEDUIiE

THE FOLLOWING KEY MILESTONES HAVE  BEEN ESTABLISHED FOR THIS PROJECT:
        APPROVE REMEDIAL ACTION  (SIGN ROD)
        AWARD COOPERATIVE AGREEMENT  TO SACWSD FOR DESIGN
        INITIATE DESIGN
        COMPLETE DESIGN
        START SECOND OPERABLE UNIT RI/FS
        AWARD COOPERATIVE AGREEMENT  TO SACWSD
         FOR CONSTRUCTION
        BEGIN CONSTRUCTION
        STARTUP OF GAG UNITS
        COMPLETE CONSTRUCTION
#FA
FUTURE ACTIONS
JUNE 1987
JUNE 1987
JUNE 1987
JANUARY 1988
MARCH 1987

DECEMBER 1987
FEBRUARY 1988
SEPTEMBER 1988
DECEMBER 1988.
A SUBSEQUENT FEASIBILITY  STUDY  IS  ONGOING WHICH WILL ADDRESS WHETHER AQUIFER RESTORATION IS APPROPRIATE.   EPA
IS CURRENTLY CONDUCTING THE  RI  STUDIES  NECESSARY TO SUPPORT SUCH A FEASIBILITY STUDY  (FS), AND THE FS REPORT
IS ANTICIPATED IN EARLY FY 1988.   EPA IS  INVESTIGATING WHETHER OR NOT FURTHER RESPONSE ACTIONS, IN ADDITION
TO AQUIFER RESTORATION, MAY  BE  NECESSARY  AT THE EPA'S RMA OFF-POST SITE TO PROTECT HUMAN HEALTH AND THE
ENVIRONMENT.  THE ARMY IS CONDUCTING ON-POST RI/FS ACTIVITIES AND IS SCHEDULING COMPLETION OF A CLEANUP
MASTER PLAN IN 1989.

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#TMA
TABIiES, MEMORANDA, ATTACHMENTS

#RS
APPENDIX A

FINAL
RESPONSIVENESS SUMMARY
FOR THE FIRST OPERABLE UNIT

THE ROCKY MOUNTAIN ARSENAL OFF-POST RI/FS SITE
COMMERCE CITY, COLORADO

JUNE 1987

THE U.S. ENVIRONMENTAL PROTECTION AGENCY (EPA) HAS PREPARED THIS COMMUNITY RELATIONS RESPONSIVENESS SUMMARY
FOR THE FIRST OPERABLE UNIT OF THE EPA PORTION OF THE ROCKY MOUNTAIN ARSENAL (RMA) OFF-POST SITE. THIS
RESPONSIVENESS SUMMARY IS DIVIDED INTO THE SECTIONS BELOW.

SECTION I. INTRODUCTION AND BACKGROUND. THIS SECTION
PROVIDES A BRIEF INTRODUCTION TO THE SITE AS
WELL AS INVESTIGATIONS AND REMEDIAL ACTIONS
TAKEN TO ADDRESS THE DRINKING WATER
CONTAMINATION.

SECTION II. THE COMMUNITY RELATIONS PROGRAM AT THE RMA
OFF-POST SITE. THIS SECTION PROVIDES A BRIEF
HISTORY OF COMMUNITY RELATIONS ACTIVITIES
DURING THE REMEDIAL INVESTIGATION ACTIVITIES
AT THE SITE.

SECTION III. SUMMARY OF MAJOR COMMENTS RECEIVED AND EPA'S
RESPONSES. THIS SECTION SUMMARIZES COMMENTS
RECEIVED IN THE CATEGORIES BELOW.

- COMMENTS RECEIVED FROM INCEPTION OF THE
PROJECT THROUGH NOVEMBER 1986.

- COMMENTS RECEIVED DURING THE PUBLIC
COMMENT PERIOD (DECEMBER 12, 1986 THROUGH
JANUARY 7, 1987) ON THE REMEDIAL
INVESTIGATION AND FEASIBILITY STUDY
REPORTS FOR THE FIRST OPERABLE UNIT.

- COMMENTS RAISED AFTER THE CLOSE OF THE
PUBLIC COMMENT PERIOD.

THIS SECTION CATEGORIZES WRITTEN AND ORAL
COMMENTS BY RELATED TOPICS AND GENERALLY
INDICATES THE SOURCES OF THE COMMENTS.

SUMMARIES OF EPA'S RESPONSES TO THESE
COMMENTS ARE ALSO PROVIDED.

I. INTRODUCTION AND BACKGROUND

A DESCRIPTION OF THE OFF-POST RI/FS SITE IS INCLUDED IN THE REMEDIAL INVESTIGATION AND FEASIBILITY STUDY
REPORTS.

IN THE SUMMER OF 1985, AREA MEDIA BEGAN TO PUBLISH STORIES ABOUT THE CHEMICAL TRICHLOROETHYLENE (TCE) THAT
HAD BEEN DISCOVERED BY EPA AND THE SOUTH ADAMS COUNTY WATER AND SANITATION DISTRICT (SACWSD) IN SOME OF THE
WATER DISTRICT'S PUBLIC WELLS AND SOME PRIVATE WELLS. SACWSD PROVIDES WATER TO THE 30,000 RESIDENTS OF
COMMERCE CITY. THE STORIES RAISED CONSIDERABLE CONCERN AMONG AREA RESIDENTS AND THEIR ELECTED
REPRESENTATIVES AT ALL LEVELS. EPA DETERMINED THAT THE TCE CONTAMINATION WARRANTED MORE IMMEDIATE ATTENTION,
AND THAT A TEMPORARY SYSTEM TO DELIVER CLEAN WATER TO AFFECTED COMMERCE CITY RESIDENTS WOULD BE A FIRST
PRIORITY IN THE RESPONSE ACTIONS AT THE SITE. INITIAL ACTIVITIES INCLUDED INSTALLATION OF TEMPORARY GRANULAR

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ACTIVATED CARBON (GAG) TREATMENT SYSTEMS AT THREE OF THE SACWSD WELL SITES AND A PRIVATE WELL HOOKUP PROGRAM,
UNDER EPA'S REMOVAL AUTHORITY.

TREATMENT OF THE SOUTH ADAMS COUNTY PUBLIC DRINKING WATER WITH A PERMANENT TREATMENT SYSTEM HAS BEEN
DESIGNATED THE FIRST OPERABLE UNIT OF EPA'S RMA OFF-POST SITE. FOR THE SECOND OPERABLE UNIT, EPA WILL
INVESTIGATE THE POTENTIAL FOR CONTROL OF CONTAMINANT MIGRATION AND SOURCE REMOVAL. A REMEDIAL INVESTIGATION
AND FEASIBILITY STUDY (RI/FS) FOR THE FIRST OPERABLE UNIT WAS COMPLETED IN THE FALL OF 1986. EPA PROPOSED TO
INSTALL A PERMANENT CENTRALIZED GRANULAR ACTIVATED CARBON WATER FILTRATION SYSTEM AS THE PREFERRED
ALTERNATIVE FOR REMEDIAL ACTION FOR THE FIRST OPERABLE UNIT, AND CONDUCTED A PUBLIC COMMENT PERIOD (DECEMBER
12, 1986 THROUGH JANUARY 7, 1987) ON THAT AND OTHER ALTERNATIVES. OTHER TREATMENT ALTERNATIVES EVALUATED
INCLUDED AIR STRIPPING FOR DIFFERENT TYPES OF CONTAMINANTS AND A COMBINATION OF GAG WITH AIR STRIPPING.

IN GENERAL, COMMUNITY REACTION TO EPA'S PREFERRED ALTERNATIVE OF INSTALLING A GRANULAR ACTIVATED CARBON
FILTRATION SYSTEM HAS BEEN FAVORABLE. THE MAJORITY OF COMMENTERS SUPPORTED THAT ALTERNATIVE, INCLUDING THE
CITIZENS AGAINST CONTAMINATION (CAC), THE COLORADO DEPARTMENT OF HEALTH (CDH), THE SOUTH ADAMS COUNTY WATER
AND SANITATION DISTRICT (SACWSD), THE TRI-COUNTY HEALTH DEPARTMENT, THE CITY OF COMMERCE CITY, THE ADAMS
COUNTY COMMISSION, AND ADAMS COUNTY SCHOOL DISTRICT 14. THE ONLY EXCEPTION WAS THE LAW FIRM OF HOLME,
ROBERTS AND OWEN. THE U.S. ARMY COMMENTED THAT "THE TREATMENT ALTERNATIVE SELECTED APPEARS TECHNICALLY SOUND
FOR REMEDIATION OF THE WATER TO AN ACCEPTABLE QUALITY.". SOME COMMENTERS HAD SPECIFIC TECHNICAL QUESTIONS
REGARDING THE GROUND WATER MODELS IN THE RI/FS REPORT AND REGARDING THE RISK ASSESSMENT. ALL THE COMMENTS
RECEIVED AND EPA'S RESPONSES ARE SUMMARIZED IN SECTION III OF THIS RESPONSIVENESS SUMMARY.

II. THE COMMUNITY RELATIONS PROGRAM AT EPA'S PORTION OF THE RMA OFF-POST SITE

A SUMMARY OF COMMUNITY RELATIONS ACTIVITIES CONDUCTED BY EPA IS INCLUDED IN ATTACHMENT A.

SINCE THE DISCOVERY OF TCE IN THE GROUND WATER, COMMUNITY CONCERN ABOUT EPA'S PORTION OF THE RMA OFF-POST
SITE HAS BEEN HIGH. ON SEVERAL OCCASIONS, NEW INFORMATION ABOUT THE SITE HAS BEEN FRONT-PAGE NEWS IN ONE OR
BOTH OF THE DENVER DAILY NEWSPAPERS. A CITIZEN INTEREST GROUP, CITIZENS AGAINST CONTAMINATION (CAC), WAS
FORMED IN THE SUMMER OF 1985 AT THE TIME OF THE DISCOVERY OF THE TCE IN THE GROUND WATER, AND IT HAS BEEN
ACTIVE SINCE THAT TIME.

EPA'S COMMUNITY RELATIONS PROGRAM HAS RESPONDED TO THIS INTEREST AT THE SITE. IN THE SPRING OF 1986, THE
AGENCY PREPARED AND DISTRIBUTED WIDELY A VIDEOTAPE THAT ANSWERED COMMON QUESTIONS RESIDENTS HAVE HAD
REGARDING THE TCE IN THEIR WATER. EPA ALSO HAS PUBLISHED THREE FACT SHEETS ON THE SITE. THE FIRST ONE, IN
FEBRUARY 1986, PROVIDED THE PUBLIC WITH A DIRECTORY OF AGENCIES AND CONTACTS FOR ISSUES RELATING TO THE SITE.
THE SECOND FACT SHEET, IN AUGUST 1986, DESCRIBED THE SITE, RI/FS PLANS AT THE SITE, OTHER STUDIES IN PROGRESS
IN THE AREA, MAJOR AGENCIES INVOLVED AT THE SITE, AND THE SUPERFUND COMMUNITY RELATIONS PROGRAM. THE THIRD
FACT SHEET, ISSUED IN DECEMBER 1986 UPON THE RELEASE OF THE RI/FS REPORT, DESCRIBED THE REMEDIAL ALTERNATIVES
UNDER CONSIDERATION AND PROVIDED INFORMATION ABOUT THE PUBLIC COMMENT PROCESS.

AT KEY POINTS DURING THE RI/FS, EPA HAS ISSUED PRESS RELEASES AND HELD PRESS CONFERENCES TO KEEP THE PUBLIC
INFORMED AS NEW INFORMATION BECAME AVAILABLE. EPA HAS ATTENDED ALL OF THE CAC PUBLIC MEETINGS. THESE
MEETINGS WERE HELD JULY 24 AND NOVEMBER 25, 1985; AND FEBRUARY 13, MARCH 5, AND MAY 22, 1986. IN ADDITION,
EPA HAS RESPONDED TO NUMEROUS CITIZEN, VENDOR, AND PRESS INQUIRIES; KEPT ELECTED U.S. OFFICIALS INFORMED OF
SITE ACTIVITIES; AND MET WITH AREA RESIDENTS ON MANY OCCASIONS.

EPA RELEASED THE DRAFT RI/FS REPORT ON THE FIRST OPERABLE UNIT TO THE PUBLIC ON DECEMBER 12, 1986, AND HELD A
PUBLIC COMMENT PERIOD ON THE REPORT FROM DECEMBER 12, 1986 THROUGH JANUARY 7, 1987. THE AGENCY PROVIDED AN
OPPORTUNITY FOR A PUBLIC MEETING DURING OR FOLLOWING THE PUBLIC COMMENT PERIOD BUT DID NOT RECEIVE ANY
REQUEST FOR SUCH A MEETING.

III. SUMMARY OF COMMENTS RECEIVED AND EPA'S RESPONSES

THIS SECTION SUMMARIZES CONCERNS THE PUBLIC HAS EXPRESSED DURING THE REMEDIAL INVESTIGATION FOR THE FIRST
OPERABLE UNIT AND EPA'S RESPONSES TO THESE CONCERNS.

A. SUMMARY OF COMMENTS RECEIVED FROM INCEPTION OF THE REMEDIAL INVESTIGATION THROUGH NOVEMBER 1986

THE HIGH LEVEL OF COMMUNITY INTEREST IN EPA'S PORTION OF THE RMA OFF-POST SITE IS SHOWN IN A CONTINUING
PATTERN OF COMMUNITY CONCERNS, QUESTIONS, AND COMMENTS EXPRESSED TO EPA. EPA HAS SUMMARIZED THE COMMENTS
RECEIVED DURING THE REMEDIAL INVESTIGATION THROUGH NOVEMBER 1986 IN THE FOUR GROUPS BELOW.

- HEALTH CONCERNS.

- TECHNICAL ISSUES.

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- ECONOMIC AND SOCIAL ISSUES.

- PROCESS ISSUES.

EPA'S RESPONSES TO THE PUBLIC'S QUESTIONS AND COMMENTS ARE SUMMARIZED FOLLOWING EACH ITEM.

HEALTH CONCERNS

1. COMMENT: NUMEROUS RESIDENTS HAVE EXPRESSED CONCERN THAT CONTAMINATED WATER COULD CAUSE HEALTH PROBLEMS.

EPA'S RESPONSE: EPA PREPARED A PRELIMINARY RISK ASSESSMENT (CAMP DRESSER & MCKEE, APRIL 17, 1986) AND A
PUBLIC HEALTH ENDANGERMENT ASSESSMENT (PART OF THE REMEDIAL INVESTIGATION REPORT, CAMP DRESSER & MCKEE,
DECEMBER 1986) TO ADDRESS THE HEALTH RISK. IN MAY 1986, EPA INSTALLED A TEMPORARY WATER TREATMENT FACILITY
TO TREAT GROUND WATER FROM SACWSD PUBLIC WATER SUPPLY WELLS. THE TEMPORARY SYSTEM IS PROVIDING SAFE DRINKING
WATER AT LEVELS BELOW THE SAFE DRINKING WATER ACT MAXIMUM CONTAMINANT LEVELS. IN THE SUMMER OF 1986, EPA
CONNECTED ALL WILLING HOUSEHOLDS WITH PRIVATE DRINKING WATER WELLS TO THE NEWLY CLEAN PUBLIC WATER SUPPLY.

2. COMMENT: A NUMBER OF RESIDENTS EXPRESSED CONFUSION REGARDING THE MEANING OF DRINKING WATER STANDARDS.

EPA'S RESPONSE: UNDER THE SAFE DRINKING WATER ACT (SDWA) , EPA HAS SET MAXIMUM CONTAMINANT LEVELS (MCLS) AND
MAXIMUM CONTAMINANT LEVEL GOALS (MCLGS) FOR CONTAMINANTS IN PUBLIC DRINKING WATER SUPPLIES. MCLGS ARE
NON-ENFORCEABLE HEALTH GOALS WHICH ARE SET AT LEVELS WHICH WOULD RESULT IN NO KNOWN OR ANTICIPATED ADVERSE
HEALTH EFFECTS WITH AN ADEQUATE MARGIN OF SAFETY. MCLS ARE ENFORCEABLE STANDARDS AND ARE SET AS CLOSE TO THE
MCLGS AS IS FEASIBLE. MCLS ARE BASED UPON TREATMENT TECHNOLOGIES, COSTS AND OTHER FEASIBILITY FACTORS SUCH
AS THE AVAILABILITY OF ANALYTICAL METHODS, TREATMENT TECHNOLOGIES AND COSTS FOR ACHIEVING VARIOUS LEVELS OF
REMOVAL. SEE GENERALLY, 50 FED. REG. 46880 ET SEQ., NOV. 13, 1985 AND THE SAFE DRINKING WATER ACT, 42 U.S.C.
SECTION 300(F) ET SEQ.

3. COMMENT: SOME RESIDENTS ASKED QUESTIONS ABOUT THE RISKS ASSOCIATED WITH DIFFERENT ROUTES OF TCE EXPOSURE
(I.E., FROM DRINKING, OR FROM VAPORS DURING COOKING OR BATHING). THEY ALSO WANTED TO KNOW HOW LONG THEY HAVE
BEEN EXPOSED TO THE CONTAMINATION AND WHETHER A LONG PERIOD OF EXPOSURE WILL RESULT IN GRAVE HEALTH EFFECTS.

EPA'S RESPONSE: THE EPA INVESTIGATION FOR THE FIRST OPERABLE UNIT FOCUSES ON THE REMEDIATION OF CURRENT
PUBLIC WATER SUPPLY CONTAMINATION FROM SACWSD WELLS. TO-DATE, THE STUDIES HAVE NOT DETERMINED THE LENGTH OF
PREVIOUS EXPOSURE SACWSD CUSTOMERS HAVE HAD TO CONTAMINATED WATER.

AS DESCRIBED ABOVE, EPA TWICE PREPARED DOCUMENTS THAT ADDRESS RISKS TO PUBLIC HEALTH ASSOCIATED WITH
UNTREATED SACWSD GROUND WATER. THE RISK ASSESSMENTS ASSUMED THAT SACWSD CUSTOMERS INGESTED TWO LITERS PER
DAY, AND SHOWERED FOR TEN MINUTES PER DAY, WITH UNTREATED WATER. A POTENTIAL EXCESS CANCER RISK OF 10-6 (ONE
EXCESS CANCER IN EVERY ONE MILLION INDIVIDUALS EXPOSED THROUGHOUT THEIR LIFETIMES) IS USED BY EPA AS A
GUIDELINE FOR DETERMINING AN ACCEPTABLE LEVEL OF EXPOSURE WITHIN ONE OR TWO ORDERS OF MAGNITUDE. THE RISK
ASSESSMENTS SHOWED THAT EXPOSURE BY INGESTION OR INHALATION, OR BY BOTH ROUTES CONCURRENTLY, TO UNTREATED
WATER FROM THE SACWSD SYSTEM MAY POSE AN UNACCEPTABLE HEALTH RISK. THE ADDITIVE EXCESS CANCER RISKS FOR
LIFETIME EXPOSURE BY INGESTION AND INHALATION RANGE FROM 2 X 10-6 TO 1 X 10-4 (TABLE 6-8 IN THE RI REPORT).
INSTALLATION OF THE TEMPORARY TREATMENT SYSTEM, HOWEVER, REDUCED THE EXPOSURE TO CONTAMINATED WATER THROUGH
THE SACWSD SYSTEM TO MCLS ESTABLISHED UNDER THE SDWA.

4. COMMENT: SOME RESIDENTS ASKED WHETHER THE UNPLEASANT TASTE OF THE WATER INDICATES THE PRESENCE OF
CONTAMINATION.

EPA'S RESPONSE: THE LEVELS OF TCE AND OTHER ORGANIC CONTAMINANTS IN THE PUBLIC WATER SUPPLY ARE WELL BELOW
CONCENTRATION WHERE THE TASTE OF THE WATER WOULD BE AFFECTED.

TECHNICAL ISSUES

1. COMMENT: IN REVIEWING THE DRAFT RI/FS REPORT PROVIDED TO THE MEMORANDUM OF AGREEMENT (MOA) PARTIES, CDH
EXPRESSED THE CONCERN THAT THE RI/FS REPORT FOCUSED ON A RANGE OF CONTAMINANTS THAT WAS TOO LIMITED AND THAT
THE CHARACTERIZATION OF SOURCES ON AND OFF THE ARSENAL WAS SUBSTANTIALLY INCOMPLETE. CDH ALSO SAID THAT
SINCE NON-VOLATILE ORGANICS HAVE BEEN IDENTIFIED IN THE AQUIFER, THE ASSESSMENT OF PROPOSED TREATMENT SYSTEMS
MUST SHOW HOW THESE CONTAMINANTS WOULD BE TREATED.

EPA'S RESPONSE: EPA ADDRESSED CDH'S COMMENTS IN THE FINAL RI/FS REPORT. THE RI/FS DID NOT CHARACTERIZE
SOURCES ON AND OFF OF THE ARSENAL. A FUTURE OPERABLE UNIT REPORT MAY ADDRESS SOURCES THAT ARE CURRENTLY
BEING CHARACTERIZED BY OTHER EPA STUDIES AND THE U.S. ARMY.

2. COMMENT: IN REVIEWING THE DRAFT RI/FS REPORT PROVIDED TO MOA SIGNERS, CDH STATED THAT USE OF AIR
STRIPPING WITHOUT EMISSION CONTROLS WOULD NOT MEET COLORADO REGULATIONS TO PROTECT THE AIR, OR REQUIREMENTS

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UNDER THE 1986 SUPERFUND AMENDMENTS AND REAUTHORIZATION ACT (SARA) TO PROVIDE A PERMANENT REMEDY.

EPA'S RESPONSE: THE FINAL FS REPORT DOES ADDRESS 1986 SARA PREFERENCE FOR PROVIDING PERMANENT SOLUTIONS, AND
NARROWS THE POSSIBLE ALTERNATIVES TO THOSE THAT WOULD PROVIDE A PERMANENT REDUCTION OF THE TOXICITY,
MOBILITY, AND VOLUME OF THE CONTAMINANTS. ALSO, EPA IDENTIFIED COLORADO APPLICABLE, OR RELEVANT AND
APPROPRIATE REQUIREMENTS (ARARS) FOR AIR EMISSIONS IN THE RECORD OF DECISION.

ECONOMIC AND SOCIAL ISSUES

1. COMMENT: SEVERAL RESIDENTS EXPRESSED CONCERN THAT THEIR PROPERTY VALUES WOULD FALL AS A RESULT OF
NEGATIVE PUBLICITY ABOUT CONTAMINATION IN THEIR WATER.

EPA'S RESPONSE: IMPLEMENTATION OF TEMPORARY AND PERMANENT GROUND WATER TREATMENT SYSTEMS PROVIDES DRINKING
WATER TO SACWSD CUSTOMERS THAT MEETS ALL CRITERIA SET UNDER THE SDWA. SACWSD OFFICIALS HAVE MET WITH LOCAL
RESIDENTS AND REALTORS TO ASSURE ALL PARTIES THAT DRINKING WATER IS NOT A PROBLEM TO RESIDENTS.

2. COMMENT: SOME LOCAL OFFICIALS AND RESIDENTS EXPRESSED CONCERN THAT ECONOMIC DEVELOPMENT IN THE AREA WOULD
BE DEPRESSED AS A RESULT OF PUBLICITY ABOUT THE RMA OFF-POST RI/FS SITE.

3. COMMENT: SEVERAL RESIDENTS EXPRESSED CONCERN ABOUT COSTS THAT INDIVIDUALS WILL BEAR DUE TO PLUMBING
DAMAGE AND OTHER PROBLEMS RESULTING FROM THE CONTAMINATION FOUND AT THE RMA OFF-POST SITE AND EFFORTS TO
CLEAN IT UP.

EPA'S RESPONSE: THE VOLATILE ORGANIC COMPOUNDS THAT WERE PRESENT IN THE SACWSD WATER PRIOR TO INITIATION OF
TREATMENT IN MAY 1986 ARE NOT CORROSIVE AND WOULD NOT CAUSE DAMAGE TO PLUMBING. HOWEVER, SACWSD GROUND WATER
IS NATURALLY HARD, WHICH MIGHT CAUSE DAMAGE TO PLUMBING FROM SCALING. SACWSD FOLLOWS GUIDELINES ON WATER
PRESSURE SET BY THE COLORADO DEPARTMENT OF HEALTH.

4. COMMENT: SOME LOCAL OFFICIALS AND COMMUNITY RESIDENTS EXPRESSED CONCERN ABOUT THE NEGATIVE REPUTATION THE
CONTAMINATION WILL GIVE THE COMMUNITY.

PROCESS ISSUES

1. COMMENT: A NUMBER OF LOCAL OFFICIALS AND AREA RESIDENTS EXPRESSED CONFUSION ABOUT THE RESPECTIVE ROLES OF
THE COLORADO DEPARTMENT OF HEALTH, EPA, THE SOUTH ADAMS COUNTY WATER AND SANITATION DISTRICT, AND THE U.S.
ARMY.

EPA'S RESPONSE: EPA HAS COORDINATED ITS ACTIVITIES CONDUCTED UNDER THE OFF-POST RI/FS WITH THE U.S. ARMY,
THE STATE OF COLORADO AND SACWSD TO AVOID UNNECESSARY DUPLICATION OF EFFORT AND TO ENSURE THAT PERTINENT
INFORMATION IS SHARED BY ALL PARTIES. EPA, THE CDH, THE U.S. ARMY AND SHELL CHEMICAL COMPANY ENTERED INTO A
MEMORANDUM OF AGREEMENT ON DECEMBER 6, 1982 FOR THE COOPERATION, EXCHANGE OF INFORMATION, AND PARTICIPATION
OF THE PARTIES IN THE DEVELOPMENT AND IMPLEMENTATION OF APPROPRIATE RESPONSE ACTIONS FOR RELEASES OF
CONTAMINANTS AT RMA. EPA HAS RESPONSIBILITY FOR CONDUCTING AN RI/FS IN THE AREA SHOWN IN FIGURE 1 OF THE
RECORD OF DECISION, PURSUANT TO CERCLA, THE NATIONAL CONTINGENCY PLAN (NCP) AND EXECUTIVE ORDERS DELEGATING
THE FUNCTIONS OF THE PRESIDENT UNDER CERCLA.

2. COMMENT: SEVERAL RESIDENTS AND LOCAL OFFICIALS EXPRESSED CONCERN THAT STUDIES WERE GETTING IN THE WAY OF
ACTION AT THE SITE.

EPA'S RESPONSE: SUPERFUND (CERCLA) AND THE NCP REQUIRE SPECIFIC SITE INVESTIGATIONS AND ANALYSIS OF CLEANUP
ALTERNATIVES, SEE 40 CFR SECTION 300.68 OF THE NCP AND SECTIONS 104 AND 121 OF CERCLA, AS WELL AS PUBLIC
COMMENT PRIOR TO IMPLEMENTATION OF REMEDIAL ACTION. THESE STUDIES ARE NECESSARY IN ORDER TO ASSURE
PROTECTION OF PUBLIC HEALTH. THE REMOVAL ACTIONS (TO PROVIDE THE TEMPORARY GAG TREATMENT SYSTEM AND TO
CONNECT THE HOUSEHOLDS USING PRIVATE WELLS TO THE PUBLIC SYSTEM) WERE TAKEN AS QUICKLY AS NCP GUIDELINES AND
FUNDING AVAILABILITY WOULD ALLOW.

3. COMMENT: A NUMBER OF PEOPLE EXPRESSED CONCERN ABOUT WHO WOULD PAY FOR THE STUDIES AND THE CLEANUP OF
CONTAMINATION, AND FROM WHOM EPA AND THE U.S. ARMY COULD RECOVER THE COSTS.

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EPA'S RESPONSE: THE U.S. ARMY HAS PROVIDED A TOTAL OF $7,000,000 TO EPA FOR USE IN THE SELECTION, DESIGN AND
IMPLEMENTATION OF RESPONSE ACTIONS TO ADDRESS TCE CONTAMINATION IN SACWSD GROUND WATER. EPA IS CONTINUING TO
INVESTIGATE OTHER POTENTIAL SOURCES OF CONTAMINATION. IF SUCH SOURCES ARE IDENTIFIED, EPA MAY SUE
POTENTIALLY RESPONSIBLE PARTIES IN ORDER TO RECOVER STUDY AND CLEANUP COSTS. EPA MAY SEEK ADDITIONAL FUNDS
FROM THE U.S. ARMY.

4. COMMENT: IN REVIEWING THE DRAFT RI/FS REPORT PROVIDED TO MOA SIGNERS, CDH OBJECTED TO THE LIMITED REVIEW
TIME OF ONE WEEK, AS REQUESTED BY EPA. CDH SAID THAT THE MOA STIPULATES A REVIEW PERIOD OF 60 DAYS FOR MOA
PARTIES AND THAT THIS RUSH EFFORT MAY MISREPRESENT THE NATURE OF THE LONG-TERM PROBLEM. CDH ADDED THAT ITS
PLAN REVIEW AND FINAL CONCEPT APPROVAL PROCESS WOULD REQUIRE 45 DAYS PRIOR TO FINAL CDH APPROVAL.

EPA'S RESPONSE: CDH'S COMMENTS WERE RECEIVED AND INCORPORATED INTO THE FINAL RI/FS REPORT.

B. SUMMARY OF COMMENTS RECEIVED IN DECEMBER 1986 AND JANUARY 1987, AND EPA'S RESPONSES

THE COMMENTS RECEIVED ON THE FIRST OPERABLE UNIT RI AND FS DOCUMENTS DURING THE PUBLIC COMMENT PERIOD BETWEEN
DECEMBER 12, 1986 AND JANUARY 7, 1987 ARE GROUPED INTO THE FIVE CATEGORIES LISTED BELOW. EACH COMMENT IS
FOLLOWED BY A SUMMARY OF EPA'S RESPONSE TO THE COMMENT.

- REMEDIAL ALTERNATIVE PREFERENCES.

- TECHNICAL COMMENTS.

- HEALTH CONCERNS.

- FINANCIAL COMMENTS.

- COMMUNITY RELATIONS CONCERNS.

REMEDIAL ALTERNATIVE PREFERENCES

1. COMMENT: COMMENTERS GENERALLY FAVORED EPA'S PREFERRED REMEDIAL ALTERNATIVE OF INSTALLATION OF A GRANULAR
ACTIVATED CARBON TREATMENT SYSTEM. THESE COMMENTERS INCLUDED CITIZENS AGAINST CONTAMINATION (CAC), SACWSD,
CDH, THE CITY OF COMMERCE CITY, THE ADAMS COUNTY COMMISSION, ADAMS COUNTY SCHOOL DISTRICT 14, AND THE
TRI-COUNTY HEALTH DEPARTMENT. CAC EXPRESSED THE OPINION THAT NOT ALL CONTAMINANTS HAVE BEEN IDENTIFIED AS
YET, AND SUPPORTED THE ADDITION OF AIR-STRIPPING TOWERS TO REMOVE POTENTIAL CONCENTRATIONS OF OTHER
CONTAMINANTS THAT MAY NOT BE REMOVED BY THE GAG SYSTEM.

EPA'S RESPONSE: THE RECORD OF DECISION IS BASED UPON IMPLEMENTING THE GAG ALTERNATIVE. IN ADDITION, THE
REMEDY PROVIDES FOR THE POSSIBLE ADDITION OF AIR STRIPPING UNITS IF VINYL CHLORIDE IS DETECTED IN SACWSD
DRINKING WATER AND POSES A THREAT TO PUBLIC HEALTH. ATTACHMENT B TO THIS RESPONSIVENESS SUMMARY PRESENTS A
RISK ASSESSMENT FOR VINYL CHLORIDE EMISSIONS TO THE AIR FROM SUCH AIR STRIPPERS. THE RISKS ARE WITHIN EPA'S
APPROXIMATE GUIDELINES FOR DETERMINING AN ACCEPTABLE LEVEL OF EXCESS CANCER RISK. A RISK ASSESSMENT FOR
OTHER CONTAMINANTS EMITTED FROM AN AIR STRIPPER IS PRESENTED IN APPENDIX B OF THE FS REPORT. ATTACHMENT C
PRESENTS THE BEST ESTIMATE COST AT THIS TIME FOR SUCH AIR STRIPPERS.

2. COMMENT: ONE CITIZEN EXPRESSED THE OPINION THAT COMMERCE CITY SHOULD USE THE DENVER MUNICIPAL WATER
SYSTEM.

EPA'S RESPONSE: SACWSD HAS ITS OWN WATER RIGHTS IN THE ALLUVIAL AQUIFER. FURTHER, THE COST OF BUYING INTO
THE DENVER SYSTEM WOULD BE APPROXIMATELY $30,000,000, WHICH FAR EXCEEDS THE COSTS OF THE OTHER AVAILABLE
REMEDIES EVALUATED WITHOUT PROVIDING SUBSTANTIALLY GREATER PUBLIC HEALTH BENEFITS.

TECHNICAL COMMENTS

1. COMMENT: A CONTRACTOR REPRESENTATIVE OF THE U.S. ARMY ASKED WHAT PROBLEMS HAD BEEN OBSERVED WITH THE
LEASED ACTIVATED CARBON SYSTEM CURRENTLY IN OPERATION IN SACWSD.

EPA'S RESPONSE: SACWSD OPERATIONS PERSONNEL REPORT THAT THERE ARE NO OPERATIONAL PROBLEMS WITH THE LEASED
SYSTEM AND THAT THE SYSTEM PRODUCES EFFLUENT THAT MEETS SDWA CRITERIA. HOWEVER, THEY DO REPORT THAT THE
SYSTEM IS UNDERSIZED TO MEET PEAK WATER DEMANDS.

2. COMMENT: A CONTRACTOR REPRESENTATIVE OF THE U.S. ARMY EXPRESSED THE OPINION THAT THE FS REPORT DOES NOT
APPEAR TO ADDRESS ALL REASONABLY AVAILABLE ALTERNATIVES AND TECHNOLOGIES, AND DOES NOT APPEAR TO PROVIDE
SUFFICIENT JUSTIFICATION FOR ELIMINATION OF ALTERNATIVES.

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EPA'S RESPONSE: THE FS REPORT WAS PREPARED BASED ON THE NCP AND THE EPA GUIDANCE DOCUMENT, "GUIDANCE ON
FEASIBILITY STUDIES UNDER CERCLA.". JUSTIFICATIONS FOR ELIMINATION OF ALTERNATIVES WERE CONSISTENT WITH THE
NCP.

3. COMMENT: THE SACWSD EXPRESSED THE OPINION THAT THE POSSIBLE ADDITION OF AIR-STRIPPING TO THE TREATMENT
SYSTEM WILL REQUIRE USE OF A CLEARWELL SYSTEM.

EPA'S RESPONSE: THE CLEARWELL SYSTEM WILL BE IMPLEMENTED AS PART OF THE FACILITY DESIGN. THE EXPECTED COST
WOULD ADD $387,000 TO THE TREATMENT SYSTEM COST, WHICH IS INCLUDED IN THE COST SHOWN IN TABLE 3-4 OF THE FS
REPORT IN THE RECORD OF DECISION.

4. COMMENT: CDH COMMENTED THAT THE PROPOSED PARALLEL CONFIGURATION FOR A GAG TREATMENT FACILITY MAY LEAD TO
OPERATIONAL PROBLEMS IN BLENDING THE EFFLUENTS.

EPA'S RESPONSE: EACH CARBON BED WILL BE MONITORED TO DETERMINE WHEN IT IS NECESSARY TO TAKE THE BED OUT OF
SERVICE FOR CARBON REPLACEMENT. THE MONITORING OF INDIVIDUAL CARBON BEDS AND THE TREATMENT PLANT EFFLUENT
WILL ENSURE COMPLIANCE WITH APPLICABLE, OR RELEVANT AND APPROPRIATE REQUIREMENTS.

5. COMMENT: THE U.S. ARMY, THE LAW FIRM OF HOLME, ROBERTS AND OWEN, AND THE COLORADO DEPARTMENT OF HEALTH
QUESTIONED THE USE OF THE PRELIMINARY FLOW AND TRANSPORT MODELS IN THE FIRST OPERABLE UNIT RI/FS REPORT. A
SUMMARY OF THESE CONCERNS IS LISTED BELOW.

- NO RESULTS OF SENSITIVITY ANALYSIS FOR MODEL PARAMETERS OR BOUNDARY CONDITIONS WERE PRESENTED IN THE
REPORT.

- SEVERAL COMMENTERS EXPRESSED CONCERN ABOUT THE USE OF STEADY STATE RATHER THAN TRANSIENT
CALIBRATION.

- DETAILED SUMMARIES OF MODEL PARAMETERS WERE NOT PRESENTED IN THE REPORT.

- THE SOLUTE TRANSPORT MODEL WAS NOT CALIBRATED AGAINST CURRENT CONDITIONS.

- THE FLOW SYSTEM HAS NOT BEEN COMPLETELY CHARACTERIZED.

- ADDITIONAL AQUIFER TESTS THROUGHOUT THE AREA TO BE MODELED ARE REQUIRED.

- RESULTS OF THE MODELING ARE PRELIMINARY IN NATURE.

- FIELD DATA FOR TOTAL ORGANIC CARBON ARE REQUIRED FOR REALISTIC ASSESSMENT OF CONTAMINANT
RETARDATION. THE U.S. ARMY SAID THAT THEIR STUDIES INDICATE ALMOST NO RETARDATION POTENTIAL IN THE
AQUIFER MATERIAL.

EPA'S RESPONSE: THE RI REPORT STATES THAT THE PRELIMINARY MODELING EFFORTS WERE INTENDED TO PROVIDE INSIGHT
TO THE PROCESSES CONTROLLING CONTAMINANT TRANSPORT, A FRAMEWORK FOR SUMMARIZATION OF THE AQUIFER SYSTEMS, AND
THE CURRENT BEST ESTIMATE OF FUTURE CONTAMINANT CONCENTRATIONS. RESULTS OBTAINED FROM THESE PRELIMINARY
EFFORTS ARE ADEQUATE FOR PRODUCING THE PRELIMINARY ESTIMATES OF FUTURE CONCENTRATIONS AT SACWSD WELLS NEEDED
TO ASSIST IN DESIGN OF THE FIRST OPERABLE UNIT. INSUFFICIENT DETAILED FIELD INFORMATION IN THE VICINITY OF
THE PLUMES IS CURRENTLY AVAILABLE FOR EXPLICIT CALIBRATION OF THE MODELS. STUDIES ARE PLANNED FOR THE SECOND
OPERABLE UNIT TO ADDRESS THESE DATA GAPS, SINCE PLUME DEFINITION AND REMEDIATION WILL REQUIRE MORE ACCURATE
DATA. AVAILABILITY OF MORE DATA MAY JUSTIFY THE COMPLEXITY OF TRANSIT CALIBRATION OF FUTURE MODELS AND ALLOW
ADDITIONAL USES OF THE MODEL. THE APPLICABILITY OF THIS APPROACH WILL BE ASSESSED AS ADDITIONAL DATA ARE
GATHERED. IN ADDITION, TECHNICAL INFORMATION ON MODELING METHODOLOGY AND PARAMETERS IS AVAILABLE IN THE
ADMINISTRATIVE RECORD.

6. COMMENT: A CONTRACTOR REPRESENTATIVE OF THE U.S. ARMY ASKED WHY ALTERNATIVE REMEDIAL ACTIONS FOR
SEMI-VOLATILE ORGANICS ARE BEING CONSIDERED WHEN THEY WERE NOT DEFINED AS A PROBLEM IN THE RI REPORT. HE
EXPRESSED THE OPINION THAT MORE DOCUMENTATION IS NEEDED IN THE FS REPORT TO JUSTIFY HOW CONTAMINANTS OF
CONCERN WERE DETERMINED. HE ASKED IF THE DETECTION OF TCE WAS THE ONLY REASON FOR CONCERN AND WHETHER THERE
WERE OTHER CONTAMINANTS THAT CAUSED PROBLEMS.

EPA'S RESPONSE: THE FINAL RI REPORT PRESENTS DATA IDENTIFYING THE PRESENCE OF A WIDE RANGE OF LOW LEVEL
SEMI-VOLATILE AND NON-VOLATILE COMPOUNDS SCATTERED IN AREAS POTENTIALLY UPGRADIENT OF SACWSD PRODUCTION
WELLS. THE CONTAMINANTS OF CONCERN ARE DETAILED IN SECTION 6 (ENDANGERMENT ASSESSMENT) OF THE RI/FS REPORT.
THE CHEMICALS REPORTED MOST FREQUENTLY AND AT THE HIGHEST CONCENTRATIONS IN VALIDATED MONITORING WELL AND
PRIVATE WELL DATA ARE: 1,1-DICHLOROETHANE, 1,1-DICHLOROETHYLENE, TRANS-1,2-DICHLOROETHYLENE,
1,1,1-TRICHLOROETHANE, TETRACHLOROETHYLENE AND TRICHLOROETHYLENE. THESE CHEMICALS MAY BE CONSIDERED GROUND
WATER CONTAMINANTS OF PRIMARY CONCERN. A NUMBER OF OTHER ORGANIC CHEMICALS INCLUDING TOLUENE,

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CIS-1,3-DICHLOROPROPENE, PHENOL, VINYL CHLORIDE, DIBROMOCHLOROPROPANE, ANILINE, METHYLENE CHLORIDE, CARBON
TETRACHLORIDE, CHLOROFORM, HEPTACHLOR EPOXIDE, DIELDRIN, AND SEVERAL PHTHALATE ESTERS ALSO WERE DETECTED IN
SOME GROUND WATER SAMPLES FROM THE EPA OFF-POST STUDY AREA. HOWEVER, THESE CHEMICALS WERE DETECTED
INFREQUENTLY AND GENERALLY AT LOW CONCENTRATIONS. IN ADDITION, IDENTIFIED POTENTIAL CONTAMINANT SOURCES BOTH
ON AND OFF THE RMA ARE CURRENTLY BEING CHARACTERIZED AND ARE POTENTIAL SOURCES OF SEMI-VOLATILE AND
NON-VOLATILE COMPOUNDS. THE POTENTIAL FUTURE THREAT FROM THESE COMPOUNDS FORMED THE BASIS FOR CONSIDERING AN
ALTERNATIVE OF AIR STRIPPING TO ADDRESS SEMI-VOLATILE COMPOUNDS. THIS ALTERNATIVE WAS ELIMINATED IN THE
INITIAL SCREENING OF ALTERNATIVES BECAUSE THE COST OF THIS ALTERNATIVE FAR EXCEEDS THE CAPITAL AND O&M COSTS
OF OTHER ALTERNATIVES EVALUATED AND DOES NOT PROVIDE SUBSTANTIALLY GREATER PUBLIC HEALTH PROTECTION. SINCE
THE COSTS OF THE GAG AND OTHER AIR STRIPPING ALTERNATIVES (FOR VOLATILES ONLY) WERE COMPARABLE, EPA
RECOMMENDED THE GAG ALTERNATIVES OVER SUCH AIR STRIPPING ALTERNATIVES BECAUSE THE GAG SYSTEM WILL HAVE THE
GREATEST CAPABILITY, WITHOUT MODIFICATION, TO TREAT A WIDE SPECTRUM OF SUCH HAZARDOUS SUBSTANCES TO A LEVEL
THAT WILL ASSURE PROTECTION OF PUBLIC HEALTH.

7. COMMENT: THE LAW FIRM OF HOLME, ROBERTS AND OWEN AND THE CONTRACTOR REPRESENTATIVE OF THE U.S. ARMY SAID
THAT THE TREATMENT FACILITY SHOULD NOT BE DESIGNED TO TREAT GROUND WATER BASED ON THE RESULTS OF THE
PRELIMINARY MODELING EFFORT, BUT SHOULD BE BASED UPON THE CURRENT SITUATION IN SOUTH ADAMS COUNTY.

EPA'S RESPONSE: THE RISK ASSESSMENTS SHOWED THAT EXPOSURE BY INGESTION OR INHALATION, OR BY BOTH ROUTES
CONCURRENTLY, TO UNTREATED WATER FROM THE SACWSD SYSTEM MAY POSE AN UNACCEPTABLE HEALTH RISK. THE ADDITIVE
EXCESS CANCER RISKS FOR LIFETIME EXPOSURE BY INGESTION AND INHALATION RANGE FROM 2 X 10-6 TO 1 X 10-4 (TABLE
6-8 IN THE RI REPORT). THE RISK ASSESSMENTS WERE BASED ON ACTUAL CURRENT SAMPLE RESULTS FROM SACWSD WELLS
AND NOT UPON FUTURE CIRCUMSTANCES. BASED UPON THE CURRENT THREAT SHOWN IN THE RISK ASSESSMENTS, THE AGENCY
DETERMINED THAT REMEDIAL ACTION WAS REQUIRED.

THE GAG SYSTEM AND OTHER ALTERNATIVES WERE DESIGNED TO ADDRESS BOTH CURRENT AND PREDICTED FUTURE
CONCENTRATIONS IN ORDER TO ASSURE ADEQUATE PROTECTION OF PUBLIC HEALTH. HOWEVER, NO CHANGE IN DESIGN OF THE
ALTERNATIVES WOULD BE REQUIRED WITHIN THE RANGE OF EXISTING AND FUTURE PREDICTED CONCENTRATION LEVELS. THE
DESIGN IS BASED ON THE QUANTITY OF WATER TO BE TREATED.

8. COMMENT: A CONTRACTOR REPRESENTATIVE OF THE U.S. ARMY QUESTIONED WHETHER SUFFICIENT STUDIES HAVE BEEN
CONDUCTED TO ENSURE THAT BEDROCK WELLS ARE CLEAN ENOUGH FOR BLENDING WITH TREATED WATER. THE U.S. ARMY
RECOMMENDED THAT BEDROCK WELLS BE MONITORED IF BLENDING WATER FROM THEM IS GOING TO BE CONSIDERED.

EPA'S RESPONSE: DATA AVAILABLE TO-DATE INDICATE THAT THE QUALITY OF THE WATER FROM THE BEDROCK AQUIFERS IS
ADEQUATE FOR BLENDING. MONITORING WILL CONTINUE IN THE FUTURE TO VERIFY THIS SUITABILITY.

9. COMMENT: THE CONTRACTOR REPRESENTATIVE FOR THE U.S. ARMY COMMENTED THAT A PREVAILING NORTHWARD FLOW OF
GROUND WATER WOULD TAKE CONTAMINATION DIRECTLY FROM THE WOODBURY CHEMICAL COMPANY SUPERFUND SITE INTO THE
STUDY AREA FOR THE ROCKY MOUNTAIN ARSENAL OFF-POST SITE. THE U.S. ARMY EXPRESSED THE OPINION THAT THE
"GROUND WATER DIVIDE" SHOULD BE EXPLAINED.

EPA'S RESPONSE: THE GROUND WATER DIVIDE IS PRESENT DUE TO THE PRESENCE OF A HIGH BEDROCK TREND SEPARATING
THE SOUTH PLATTE VALLEY AND THE NORTH-SOUTH TRENDING PALEOCHANNEL THAT PARALLELS QUEBEC STREET. THIS FLOW
CONFIGURATION LIMITS THE POTENTIAL FOR CONTRIBUTION OF CONTAMINATION TO SACWSD WELLS FROM THE WOODBURY SITE.

10. COMMENT: THE CONTRACTOR REPRESENTATIVE FOR THE U.S. ARMY ASKED WHEN THE FS FOR THE OTHER OPERABLE UNITS
WILL BE PERFORMED AND WHETHER SURFACE WATER WILL BE CONSIDERED AN OPERABLE UNIT.

EPA'S RESPONSE: THE SECOND OPERABLE UNIT WILL CONSIDER PRIMARILY AQUIFER CLEANUP OPTIONS. TREATMENT OF
GROUND WATER USED FOR DRINKING SERVES THE DUAL PURPOSE OF MEETING SACWSD DEMAND WITH THEIR EXISTING WATER
RIGHTS AND AIDING IN ULTIMATE CLEANUP OF THE AQUIFER SYSTEM. EPA WILL EVALUATE SURFACE WATER CONTAMINATION
IN THE STUDY AREA.

11. COMMENT: THE LAW FIRM OF HOLME, ROBERTS AND OWEN EXPRESSED THE OPINION THAT THE RISK ASSESSMENT IS BASED
ON UNREALISTICALLY CONSERVATIVE ESTIMATES OF THE SITUATION. THEY SAID THAT IF EPA HAD USED MORE REALISTIC
ESTIMATES, THE HAZARDS MAY NOT BE AS SEVERE AS PRESENTED.

EPA'S RESPONSE: THE RISK ASSESSMENT TECHNIQUES UTILIZED ARE STANDARD TO EPA AND UTILIZED AT SUPERFUND SITES.
THESE TECHNIQUES WERE DEVELOPED AFTER CONSIDERABLE SCIENTIFIC AND PUBLIC COMMENT. QUANTITIES OF WATER
INGESTED AND WATER UTILIZED FOR OTHER PURPOSES, SUCH AS SHOWERS, ARE REALISTIC, WORST-CASE ESTIMATES WHICH
ASSURE ADEQUATE PROTECTION OF PUBLIC HEALTH. THIS APPROACH DOES PROVIDE A BASIS FOR COMPARISON FOR THE RISK
ANALYSIS.

12. COMMENT: THE CONSULTANT TO SACWSD EXPRESSED THE OPINION THAT IF EPA DETERMINES THAT MAXIMUM CONTAMINANT
LEVEL GOALS (MCLGS) SHOULD BE MET BY THE WATER TREATMENT FACILITY, THEN SACWSD SHOULD VERIFY THAT THE
RECOMMENDED DOWNFLOW, FIXED-BED GAG TREATMENT PROCESS IS CAPABLE OF COST-EFFECTIVELY MEETING THESE STRINGENT

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STANDARDS.

EPA'S RESPONSE: EPA HAS DETERMINED THAT THE MAXIMUM CONTAMINANT LEVELS (MCLS) IN THE SAFE DRINKING WATER ACT
ARE THE APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS FOR THIS OPERABLE UNIT.

13. COMMENT: CDH PROVIDED A LIST OF THE APPLICABLE OR RELEVANT AND APPROPRIATE STATE STANDARDS,
REQUIREMENTS, LIMITATIONS, AND CRITERIA ("REQUIREMENTS") FOR THE MANAGEMENT OF WASTES AT THE RMA ON- AND
OFF-POST SITES. CDH RESERVED THE RIGHT TO AMEND THE LIST IF ANY MORE REGULATIONS OR STANDARDS ARE
IDENTIFIED.

EPA'S RESPONSE: EPA HAS DISCUSSED THE LIST WITH THE STATE, THE STATE HAS PROVIDED A REVISED LIST, AND THE
RECORD OF DECISION IDENTIFIES THE APPLICABLE OR RELEVANT AND APPROPRIATE STATE REQUIREMENTS.

14. COMMENT: CDH SAID IT IS THE POSITION OF THE STATE OF COLORADO THAT ALTHOUGH PERMITS MAY NOT BE REQUIRED
FOR CERTAIN ACTIVITIES AT THE ARSENAL, THE REQUIREMENTS OF THE STATE OF COLORADO GOVERNING ALL INFORMATION
SUBMITTALS, NOTIFICATION REQUIREMENTS, MONITORING, DATA COLLECTION, AND DATA REPORTING REQUIREMENTS ARE
APPLICABLE AT THE RMA ON- AND OFF-POST SITES.

EPA'S RESPONSE: EPA'S RESPONSE IS SET FORTH IN APPENDIX B TO THE RECORD OF DECISION.

15. COMMENT: CDH, THE U.S. ARMY, AND THE LAW FIRM OF HOLME, ROBERTS AND OWEN MADE COMMENTS ON THE SOURCES OF
CONTAMINATION AT THE RMA OFF-POST SITE. HOLME, ROBERTS AND OWEN SAID THAT PLUME MAPS WOULD HELP TO IDENTIFY
SOURCES OF CONCERN RATHER THAN TO INFER THAT THE ARSENAL IS THE MAJOR SOURCE OF MANY CONTAMINANTS AT THE RMA
OFF-POST SITE. CDH SUGGESTED THAT EPA REMOVE FROM THE FS REPORT ALL DISCLAIMERS CONCERNING THE LACK OF
INTENT TO IDENTIFY CONTRIBUTING SOURCES OF CONTAMINATION AT THE SITE, SINCE THE RI REPORT DISCUSSES POTENTIAL
SOURCES OF CONTAMINATION AT LENGTH, AND THE PURPOSE OF AN RI IS TO IDENTIFY SOURCES OF CONTAMINATION. THE
CONTRACTOR REPRESENTATIVE OF THE U.S. ARMY STATED THAT THE CONTAMINANT CONCENTRATION MAPS PRESENTED SUGGEST
SOURCE AREAS OTHER THAN RMA. THE MODELING EFFORT SHOULD BE CONSIDERED THE INITIAL PHASE OF A MORE DETAILED
STUDY USING SITE SPECIFIC DATA.

EPA'S RESPONSE: INSUFFICIENT INFORMATION ON POTENTIAL SOURCES IS CURRENTLY AVAILABLE FOR IDENTIFICATION OF
OR APPORTIONMENT OF RESPONSIBILITY TO INDIVIDUAL SOURCES. THE SELECTION, IDENTIFICATION, EVALUATION AND
DESIGN OF TREATMENT ALTERNATIVES FOR THE SACWSD DRINKING WATER DO NOT REQUIRE IDENTIFICATION OF THE
RESPONSIBLE SOURCES. EFFORTS TO IDENTIFY THE RESPONSIBLE SOURCES ON AND OFF THE ARSENAL ARE CONTINUING.

HEALTH CONCERNS

1. COMMENT: A LOCAL RESIDENT ASKED IF THE WATER IS SAFE TO DRINK.

EPA'S RESPONSE: EPA EXPLAINED THAT THE TEMPORARY WATER TREATMENT SYSTEM THAT EPA ARRANGED FOR SACWSD IS
PROVIDING SAFE WATER AT LEVELS AT OR BELOW THE SDWA MAXIMUM CONTAMINANT LEVELS UNTIL INSTALLATION OF THE
PERMANENT TREATMENT SYSTEM. EPA ALSO EXPLAINED THE PUBLIC COMMENT PROCESS AND ENCOURAGED THE RESIDENT TO
REVIEW THE DOCUMENTS DESCRIBING THE PROPOSED REMEDIAL ALTERNATIVES AND TO COMMENT ON THEM.

FINANCIAL COMMENTS

1. COMMENT: A LOCAL RESIDENT ASKED IF THE EXPENDITURES ON A PERMANENT WATER TREATMENT SYSTEM CAN BE
JUSTIFIED WHEN, IN HIS OPINION, SACWSD WILL EVENTUALLY HAVE TO USE SURFACE WATER IN THE FUTURE.

EPA'S RESPONSE: EPA SAID THAT IT IS CURRENTLY EVALUATING HOW TO CLEAN UP THE GROUND WATER; THUS, IT IS
PREMATURE TO ASSUME THAT SURFACE WATER WILL HAVE TO BE USED IN THE FUTURE. ADDITIONALLY, THE COST OF
PROVIDING SURFACE WATER FAR EXCEEDS THE COST OF OTHER ALTERNATIVES EVALUATED, WITHOUT PROVIDING GREATER
PUBLIC HEALTH BENEFITS.

2. COMMENT: IN THE INTERESTS OF COST-EFFECTIVENESS, CITIZENS AGAINST CONTAMINATION RECOMMENDED INSTALLATION
OF THE GAG SYSTEM AS SOON AS POSSIBLE.

EPA'S RESPONSE: THE RECORD OF DECISION IS BASED UPON IMPLEMENTATION OF THE GAG SYSTEM ALTERNATIVE. THE
PERMANENT SYSTEM SHOULD BE IN OPERATION BY SEPTEMBER 1988.

COMMUNITY RELATIONS CONCERNS

1. COMMENT: ONE RESIDENT EXPRESSED THE OPINION THAT THE PROBLEM OF DELIVERING CLEAN WATER SHOULD BE SOLVED
IN TERMS OF GROWTH.

EPA'S RESPONSE: EPA RESPONDED THAT IT IS THE AGENCY'S HOPE THAT WITH A PERMANENT SYSTEM FOR PROVIDING SAFE
WATER, THE CITIZENS OF COMMERCE CITY WILL NOT SEE A NEGATIVE EFFECT ON GROWTH.

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2. COMMENT: CAC AND SACWSD BOTH EXPRESSED APPRECIATION TO EPA FOR ITS CONCERN ABOUT THE PROBLEM, FOR THE
OPPORTUNITY TO COMMENT ON THE PROPOSED REMEDIAL ALTERNATIVES, AND FOR THE COOPERATIVE SPIRIT IN WHICH THEY
HAVE WORKED. CAC ADDED THAT THE PROCESS AT THE RMA OFF-POST SITE HAS EXEMPLIFIED WHAT CAN BE ACCOMPLISHED
WHEN CITIZENS' GROUPS AND THE GOVERNMENT WORK TOGETHER.

EPA'S RESPONSE: NO RESPONSE REQUIRED.

C. SUMMARY OF COMMENTS RAISED AFTER THE CLOSE OF THE PUBLIC COMMENT PERIOD

EPA RECEIVED ADDITIONAL COMMENTS DATED MARCH 5, 1987 FROM THE U.S. ARMY. ALTHOUGH EPA IS NOT REQUIRED TO
RESPOND TO COMMENTS RECEIVED AFTER THE PUBLIC COMMENT PERIOD CLOSES, THE AGENCY BELIEVES IT IS IMPORTANT TO
RESPOND TO THESE COMMENTS BECAUSE OF THE U.S. ARMY'S SUBSTANTIAL PARTICIPATION IN THE PROJECT. THE U.S.
ARMY'S GENERAL COMMENTS AND EPA'S RESPONSES ARE SUMMARIZED BELOW. CERTAIN COMMENTS RAISED IN THE U.S. ARMY'S
MARCH 5, 1987 LETTER OF COMMENT WERE RAISED EARLIER BY THEIR CONTRACTOR AND HAVE ALREADY BEEN ADDRESSED IN
SECTION III. B OF THIS RESPONSIVENESS SUMMARY.

1. COMMENT: THE U.S. ARMY SUGGESTED THAT THE TITLE OF THE RI/FS REPORT BE CHANGED. THEY SAID THAT RMA IS
JUST ONE OF MANY PARTIES POTENTIALLY RESPONSIBLE FOR THE CONTAMINATION THAT EXISTS IN THE SACWSD DISTRIBUTION
SYSTEM, AND THE TITLE SHOULD REFLECT THIS BROADER RESPONSIBILITY.

EPA'S RESPONSE: THE AGENCY HAS DETERMINED THAT A TITLE CHANGE IS INAPPROPRIATE. THE RMA IS A PROPOSED NPL
SITE, AND RMA IS ONE OF TWO OR MORE POTENTIAL SOURCES OF SOUTH ADAMS COUNTY GROUND WATER CONTAMINATION.

2. COMMENT: THE U.S. ARMY SAID THAT EPA'S PREFERENCE FOR THE GAG ALTERNATIVE RELIES HEAVILY ON POSSIBLE
FUTURE SEMI-VOLATILE AND NON-VOLATILE CONTAMINATION THAT CANNOT BE EXTRAPOLATED FROM THE EXISTING DATA. THE
U.S. ARMY RECOMMENDED THAT ADDITIONAL JUSTIFICATION BE PROVIDED BEFORE THIS METHOD OF TREATMENT IS SELECTED
AS THE PREFERRED ALTERNATIVE.

EPA'S RESPONSE: THE DETAILED SCREENING PROCESS IN THE FS IDENTIFIED THREE ALTERNATIVES THAT WERE COMPARABLE
IN THE COST EFFECTIVENESS ANALYSIS. THESE ALTERNATIVES ARE:

- GAG.

- AIR STRIPPING WITH OFF-GAS TREATMENT.

- AIR STRIPPING WITH OFF-GAS TREATMENT AT WELLS 14 AND 16. GAG AT WELLS 2, 3, 5, 15 AND 17.

SINCE THE COSTS OF THESE ALTERNATIVES ARE COMPARABLE, EPA RECOMMENDED THE GAG ALTERNATIVE OVER AIR STRIPPING
BECAUSE OF ITS ABILITY TO DEAL EFFECTIVELY WITH SEMI-VOLATILE AND NON-VOLATILE ORGANIC COMPOUNDS, WITHOUT
MODIFICATION, IN THE EVENT SUCH COMPOUNDS POSE A THREAT TO SACWSD WELLS AND PUBLIC HEALTH IN THE FUTURE.

3. COMMENT: THE U.S. ARMY STATED THAT ALL OF THE AIR STRIPPING ALTERNATIVES WERE EVALUATED AND COMPARED TO
THE GAG ALTERNATIVE BASED ON THEIR REMOVAL EFFICIENCY FOR DIISOPROPYLMETHYLPHOSPHONATE (DIMP) AND
DICYCLOPENTADIENE (DCPD), TWO RMA-SPECIFIC COMPOUNDS NOT LIKELY TO BE ENCOUNTERED IN THE STUDY AREA. IF THE
TREATMENT EFFICIENCY FOR SEMI-VOLATILE AND NON-VOLATILE COMPOUNDS IS TO BE USED AS AN EVALUATION CRITERION,
COMPOUNDS LIKELY TO BE ENCOUNTERED IN THE STUDY SHOULD BE USED.

EPA'S RESPONSE: TWO BASIC AIR STRIPPING ALTERNATIVES WERE DEVELOPED. THE FIRST EVALUATED AIR STRIPPING OF
VOLATILE ORGANIC COMPOUNDS. THE SECOND EVALUATED AIR STRIPPING OF BOTH VOCS AND SEMI-VOCS INCLUDING DIMP AND
DCPD. BOTH OF THESE ALTERNATIVES WERE COMPARED AGAINST GAG. AIR STRIPPING OF ONLY VOCS WAS COMPARABLE ON A
COST-EFFECTIVE BASIS TO THE GAG ALTERNATIVE. AIR STRIPPING FOR SEMI-VOLATILES WAS EXCLUDED DURING THE
INITIAL SCREENING BECAUSE THE COST OF THIS ALTERNATIVE FAR EXCEEDS THE CAPITAL AND O&M COSTS OF OTHER
ALTERNATIVES EVALUATED AND DOES NOT PROVIDE SUBSTANTIALLY GREATER PUBLIC HEALTH PROTECTION.

4. COMMENT: THE U.S. ARMY RECOMMENDED THAT EPA GIVE GREATER CONSIDERATION TO THE PROBLEMS ASSOCIATED WITH
USING A GAG SYSTEM TO TREAT POLAR COMPOUNDS, SUCH AS VINYL CHLORIDE AND CHLOROFORM. THESE COMPOUNDS ARE AS
LIKELY, IF NOT MORE LIKELY, TO BE ENCOUNTERED IN THE SACWSD SYSTEM AS THOSE SEMI-VOLATILE AND NON-VOLATILE
COMPOUNDS CONSIDERED AS PROBLEMATIC TO THE AIR STRIPPING.

EPA'S RESPONSE: EPA IS CONTINUING TO MONITOR FOR VINYL CHLORIDE AND OTHER HAZARDOUS SUBSTANCES. THE
SELECTED REMEDY PROVIDES FOR THE ADDITION OF AN AIR STRIPPING FACILITY TO TREAT VINYL CHLORIDE IN THE EVENT
THAT VINYL CHLORIDE POSES A THREAT TO THE SACWSD SUPPLY WELLS AND THE PUBLIC HEALTH.

5. COMMENT: THE U.S. ARMY RECOMMENDED THAT CARBON DISPOSAL BE EVALUATED AS PART OF THE GAG ALTERNATIVE, AS
DISPOSAL MAY BE AN IMPORTANT FINANCIAL CONSIDERATION IN FINAL SELECTION OF ALTERNATIVES. THE U.S. ARMY SAID
PROBLEMS WITH OBTAINING LIABILITY INSURANCE HAVE MADE IT INCREASINGLY DIFFICULT AND EXPENSIVE TO FIND

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SUITABLE DISPOSAL AND REGENERATION FACILITIES WILLING TO ACCEPT USED CARBON FROM RMA'S OWN ON-POST GAG
TREATMENT SYSTEMS.

EPA'S RESPONSE: THE VENDORS OF GAG WHO WILL BE SOLICITED FOR SUPPLY OF EQUIPMENT AND REPLACEMENT CARBON ALL
HAVE, OR HAVE ACCESS TO, REGENERATION FACILITIES WHICH ARE UNDER RCRA PERMITS.

6. COMMENT: THE U.S. ARMY EXPRESSED THE OPINION THAT THE AIR STRIPPING ALTERNATIVE COULD BE THE MOST
EFFICIENT AND COST-EFFECTIVE MEANS OF TREATING THE SACWSD CONTAMINATION PROBLEM FOR THE REASONS LISTED BELOW.

- BOTH GAG TREATMENT AND AIR STRIPPING MERELY TRANSFER THE CONTAMINATION FROM ONE MEDIUM TO ANOTHER;
AND

- THE CONTAMINATION PROBLEM IN THE SACWSD SYSTEM IS SOLELY VOLATILE ORGANIC IN NATURE AT THIS TIME.

THE U.S. ARMY ADDED THAT A GAG UNIT COULD BE ADDED TO THE TREATMENT SYSTEM LATER IF IT SHOULD BECOME
NECESSARY BECAUSE OF A FUTURE INFLUX OF SEMI-VOLATILE AND NON-VOLATILE ORGANIC CONTAMINATION.

EPA'S RESPONSE: THE GAG ALTERNATIVE TRANSFERS THE VOCS FROM WATER TO THE ACTIVATED CARBON. SPENT CARBON
FROM THE GAG TREATMENT SYSTEM WILL BE REGENERATED AT AN INCINERATOR IN COMPLIANCE WITH SECTIONS 3004 AND 3005
OF THE SOLID WASTE DISPOSAL ACT, IN ACCORDANCE WITH SECTION 121(D)(3) OF CERCLA. THEREFORE, GAG PERMANENTLY
AND SIGNIFICANTLY REDUCES THE MOBILITY, TOXICITY AND VOLUME OF HAZARDOUS CONSTITUENTS. MOREOVER, THE
POTENTIAL INHALATION OF EMISSIONS FROM AIR STRIPPING WITHOUT OFF-GAS TREATMENT PRESENTS A GREATER RISK TO THE
PUBLIC HEALTH THAN GAG AND DOES NOT MEET THE PERMANENCY CRITERIA UNDER SECTION 121 OF CERCLA.

7. COMMENT: THE STATE HAS OBJECTED TO THE CONCLUSION IN THE RECORD OF DECISION THAT THE ARARS FOR THIS
OPERABLE UNIT ARE THE FINAL OR PROPOSED MCLS ESTABLISHED UNDER THE SAFE DRINKING WATER ACT FOR ALL
CONTAMINANTS IDENTIFIED IN SOUTH ADAMS COUNTY DRINKING WATER. (SEE MAY 22, 1987 LETTER FROM THOMAS P. LOOBY
TO JAMES SCHERER, WHICH IS ATTACHED IN APPENDIX C).

RESPONSE: EPA'S RATIONALE FOR SELECTING MCLS AS AN ARAR FOR THIS OPERABLE UNIT IS SET FORTH IN THE RECORD OF
DECISION DOCUMENT.

8. COMMENT: THE STATE HAS COMMENTED THAT INSUFFICIENT FINANCING EXISTS TO COMPLETE THE CONSTRUCTION AND
OPERATION OF THE GAG TREATMENT SYSTEM.

RESPONSE: EPA IS WORKING CLOSELY WITH THE STATE, THE ARMY AND SACWSD TO IDENTIFY SOURCES OF FUNDING.

9. COMMENT: THE STATE HAS ALSO COMMENTED THAT OTHER ARARS IDENTIFIED BY THE STATE OF COLORADO WERE NOT
DETERMINED BY EPA TO BE ARARS FOR THIS REMEDIAL ACTION.

RESPONSE: STATE ARARS ARE ADDRESSED IN THE RECORD OF DECISION, INCLUDING APPENDIX B.

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ATTACHMENT A
TO APPENDIX A

COMMUNITY RELATIONS ACTIVITIES CONDUCTED AT THE
ROCKY MOUNTAIN ARSENAL OFF-POST SITE

COMMUNITY RELATIONS ACTIVITIES CONDUCTED AT THE ROCKY MOUNTAIN ARSENAL OFF-POST SITE FROM APRIL 1985 THROUGH
JANUARY 1987 ARE LISTED BELOW.

- PUBLIC AFFAIRS TASK GROUP OF MEMORANDUM OF AGREEMENT (MOA) PARTIES IS FORMED (AUGUST 1984) .

- TRI-COUNTY HEALTH DEPARTMENT FOLLOWED UP RESIDENTIAL WATER SAMPLING WITH LETTERS INFORMING
RESIDENTS OF SAMPLING RESULTS AFTER EACH SAMPLING EVENT.

- EPA MET WITH COLORADO CITIZEN ACTION NETWORK (CCAN) AND METROPOLITAN ORGANIZATION FOR PEOPLE (MOP)
ABOUT EPA'S STUDIES IN SOUTH ADAMS COUNTY (MAY 1985).

- EPA ATTENDED PUBLIC MEETINGS HELD BY THE CITIZENS AGAINST CONTAMINATION (CAC) ON JULY 24 AND
NOVEMBER 25, 1985; AND FEBRUARY 13, MARCH 5, AND MAY 22, 1986.

- EPA PREPARED A FACT SHEET THAT PROVIDED THE PUBLIC WITH A DIRECTORY OF AGENCIES AND CONTACTS FOR
ISSUES RELATING TO THE SITE (FEBRUARY 1986).

- EPA CONDUCTED DISCUSSIONS WITH LOCAL OFFICIALS AND AREA RESIDENTS TO OBTAIN FIRST-HAND INFORMATION
REGARDING COMMUNITY CONCERNS ABOUT THE SITE (FEBRUARY-MARCH 1986).

- EPA PREPARED AND DISTRIBUTED WIDELY A VIDEOTAPE THAT ANSWERED COMMON QUESTIONS RESIDENTS HAVE HAD
REGARDING THE TCE IN THEIR WATER (APRIL 1986).

- EPA PREPARED AND DISTRIBUTED A FACT SHEET ON RI/FS PLANS AT THE SITE, OTHERS STUDIES IN PROGRESS IN
THE AREA, MAJOR AGENCIES INVOLVED AT THE SITE, AND THE SUPERFUND COMMUNITY RELATIONS PROGRAM
(AUGUST 1986).

- EPA HAS RESPONDED TO NUMEROUS CITIZEN, VENDOR, AND PRESS INQUIRIES (SUMMER 1985 TO PRESENT).

- EPA PREPARED AND DISTRIBUTED A FACT SHEET ON THE FS REPORT FOR THE FIRST OPERABLE UNIT, OTHER
STUDIES AT THE SITE, AND WAYS CITIZENS CAN OBTAIN FURTHER INFORMATION (DECEMBER 1986).

- EPA HELD A PUBLIC COMMENT PERIOD ON THE REMEDIAL ALTERNATIVES PROPOSED IN THE FS REPORT FOR THE
FIRST OPERABLE UNIT (DECEMBER 12, 1986 THROUGH JANUARY 7, 1987).

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                                  ATTACHMENT B
                                  TO APPENDIX A

                RISK ASSESSMENT FOR THE VINYL CHLORIDE EMISSIONS
                               FROM AIR STRIPPING

THE FOLLOWING RISK ASSESSMENT  FOR VINYL CHLORIDE EMISSIONS FROM AN AIR STRIPPER COVERS OCCUPATIONAL SAFETY
AND HEALTH ADMINISTRATION  (OSHA)  AND AMERICAN CONFERENCE OF GOVERNMENTAL INDUSTRIAL HYGIENISTS  (ACGIH)
STANDARDS AND THE 10-6 CANCER  ASSESSMENT GROUP LEVELS.  IN ADDITION, AS IDENTIFIED IN SECTION 2.3.1 OF  THE
FEASIBILITY STUDY REPORT, A NATIONAL EMISSION STANDARD FOR HAZARDOUS AIR POLLUTANTS  (NESHAPS) FOR CERTAIN
INDUSTRIAL FACILITIES MAY BE RELEVANT AND APPROPRIATE FOR SUCH AN AIR STRIPPER.

THE NESHAPS STANDARD FOR EMISSION FROM VINYL CHLORIDE PLANTS (SEE 40 CFR 61.63) IS 10 PPM, WHICH IS
APPROXIMATELY EQUIVALENT TO 21,000 UG/M3 AT 25 DEGREES C AT 5,200 FEET ELEVATION.  THE STACK EXIT
CONCENTRATION REPORTED FROM THE AIR STRIPPER IS ESTIMATED TO RANGE FROM 610 UG/M3 TO 180 UG/M3,  DEPENDING ON
LEVELS OF VINYL CHLORIDE IN THE GROUND WATER.  THE STACK EXIT CONCENTRATIONS OF VINYL CHLORIDE WOULD BE WELL
BELOW THE NESHAP STANDARD FOR  VINYL CHLORIDE PLANTS.

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                                            CLEMENT ASSOCIATES, INCORPORATED

TO:       MICHAEL J. SMITH,  CDM/DENVER

FROM:     THOMAS GOLOJUCH,  ICF/CLEMENT

DATE:     MARCH 3,  1987

PROJECT:  RMA OFF-POST RI/FS SITE/FIRST OPERABLE UNIT

SUBJECT:  HEALTH RISKS ASSOCIATED WITH POTENTIAL VINYL CHLORIDE
          EMISSIONS  FROM AN AIR STRIPPING FACILITY

DOCUMENT CONTROL NO: 198-RI 1-RT-DYGG-l

       THE FEASIBILITY STUDY (FS)  FOR  THE FIRST OPERABLE UNIT OF THE EPA'S ROCKY MOUNTAIN ARSENAL  (RMA)
OFF-POST RI/FS SITE  FOCUSES ON REMEDIATION OF PUBLIC WATER SUPPLY CONTAMINATION IN THE  RI/FS  STUDY AREA.   ONE
OF THE GROUNDWATER  TREATMENT TECHNOLOGIES UNDER CONSIDERATION FOR THE SOUTH ADAMS COUNTY WATER AND SANITATION
DISTRICT  (SACWSD) WATER SUPPLY COULD RESULT IN WORKER EXPOSURE TO VOLATILE ORGANIC COMPOUNDS  BECAUSE
EMISSIONS FROM THE  TREATMENT UNITS,  IF UNCONTROLLED, WOULD CONTAIN THE ORGANIC COMPOUNDS STRIPPED  FROM THE
CONTAMINATED WATER.  THE HEALTH RISKS  ASSOCIATED WITH EXPOSURE OF WORKERS OR NEARBY RESIDENTS TO VINYL
CHLORIDE, ONE OF THE COMPOUNDS THAT  COULD POTENTIALLY BE RELEASED AT AN SACWSD AIR STRIPPING  FACILITY,  ARE
BRIEFLY DISCUSSED BELOW.

       AS AN INDICATION OF  PLAUSIBLE MAXIMUM EXPOSURE TO ON-SITE WORKERS,  CAMP DRESSER  & MCKEE ESTIMATED  THE
CONCENTRATION OF VINYL CHLORIDE IN OFF-GASES DERIVED BY ASSUMING THAT VINYL CHLORIDE WOULD  BE PRESENT AT  10
UG/LITER OR 3 UG/LITER IN GROUNDWATER,  THAT 2 AIR STRIPPING TOWERS WOULD BE USED, AND THAT  12 MILLION GALLONS
OF CONTAMINATED GROUNDWATER WOULD BE TREATED PER DAY.  UNDER THESE ASSUMPTIONS, OFF-GASES RELEASED DIRECTLY
FROM THE TOWERS WOULD CONTAIN A COMBINED MAXIMUM VINYL CHLORIDE CONCENTRATION OF 610 UG/M3  AND 180 UG/M3  FOR
THE 10 UG/LITER AND  3 UG/LITER GROUNDWATER EXPOSURE SCENARIOS, RESPECTIVELY.  VINYL CHLORIDE  CONCENTRATIONS
AT 100 METERS FROM  THE AIR  STRIPPING TOWERS ALSO WERE CALCULATED TO PROVIDE A LESS CONSERVATIVE ESTIMATE  OF
POTENTIAL WORKER EXPOSURE AND PLAUSIBLE MAXIMUM ESTIMATE OF POTENTIAL EXPOSURE OF NEARBY RESIDENTS.   AMBIENT
CONCENTRATIONS OF VINYL CHLORIDE AT  A  DISTANCE OF 100 METERS FROM THE AIR STRIPPING TOWERS  WERE ESTIMATED AT
0.155 UG/M3 AND 0.046 UG/M3 FOR THE  10-UG/LITER AND 3-UG/LITER GROUNDWATER EXPOSURE SCENARIOS,  RESPECTIVELY.

       THE EFFECTS OF VINYL CHLORIDE ON BOTH HUMANS AND EXPERIMENTAL ANIMALS ARE DESCRIBED  IN THE  ATTACHED
TOXICITY PROFILE.   THE OCCUPATIONAL  SAFETY AND HEALTH ADMINISTRATION  (OSHA) AND THE AMERICAN  CONFERENCE OF
GOVERNMENTAL INDUSTRIAL HYGIENISTS (ACGIH)  HAVE RECOMMENDED TIME-WEIGHTED AVERAGE  (TWA) OCCUPATIONAL EXPOSURE
LIMITS OF APPROXIMATELY 2.6 MG/M3 (2,600 UG/M3) AND 10 MG/M3  (10,000 U/M3), RESPECTIVELY, FOR AIRBORNE VINYL
CHLORIDE IN THE WORKPLACE.   THESE VALUES ARE INTENDED TO PROTECT THE HEALTH OF WORKERS  EXPOSED 8 HOURS/DAY
FOR A WORKING LIFETIME TO CHEMICALS  IN THE WORKPLACE.  ALTHOUGH ACGIH VALUES ARE ONLY RECOMMENDED  GUIDELINES,
OSHA TWAS ARE LEGALLY ENFORCEABLE LIMITS.

       ACCORDING TO  EPA'S SYSTEM FOR CHARACTERIZATION OF THE OVERALL WEIGHT OF EVIDENCE FOR CARCINOGENICITY,
VINYL CHLORIDE IS CLASSIFIED IN GROUP  A,  MEANING IT IS A HUMAN CARCINOGEN BASED ON EVIDENCE FROM
EPIDEMIOLOGIC STUDIES.  A CANCER POTENCY FACTOR IS THEREFORE USED TO ESTIMATE THE POTENTIAL EXCESS CANCER
RISKS ASSOCIATED WITH EXPOSURE TO THIS COMPOUND.  THE 95% UPPER-BOUND CANCER POTENCY FOR VINYL CHLORIDE IS
7.1 X 10-6  (UG/M3)-I.  THIS VALUE IS AN ESTIMATE OF THE EXCESS CANCER RISK ASSOCIATED WITH  CONTINUOUS
INHALATION, AT A RATE OF 20 M3/DAY,  OF AMBIENT AIR CONTAINING 1 UG/M3 VINYL CHLORIDE BY A 70-KG PERSON OVER A
70-YEAR LIFETIME.

       FOR THIS ANALYSIS, IT IS ASSUMED THAT NEARBY RESIDENTS COULD POTENTIALLY BE EXPOSED  TO VINYL CHLORIDE
CONTINUOUSLY FOR A  70-YEAR  LIFETIME  OR FOR A 2-YEAR PERIOD.  IT IS ASSUMED THAT WORKERS COULD POTENTIALLY BE
EXPOSED TO VINYL CHLORIDE FOR 8 HOURS/DAY,  5 DAY/WEEK, FOR 47 YEARS  (A WORKING LIFETIME CONSTITUTING
EMPLOYMENT FROM AGE  18 TO 65)  OR FOR 2 YEARS.  THE CUMULATIVE DOSE RECEIVED DURING EITHER THE LIFETIME OR
2-YEAR EXPOSURE PERIOD WAS  THEREFORE EXPRESSED AS AN AVERAGE DAILY EXPOSURE PRORATED OVER A 70-YEAR LIFETIME,
AND THE CORRESPONDING LIFETIME RISK  WAS CALCULATED ACCORDINGLY.  THIS PROCEDURE IS RECOMMENDED IN  EPA'S
"GUIDELINES FOR CARCINOGEN  RISK ASSESSMENT"  (FEDERAL REGISTER 51:33998, SEPTEMBER 24, 1986).   BASED ON THE
EXPOSURE ASSUMPTIONS NOTED,  THE PRORATED AVERAGE DAILY EXPOSURE FOR A LIFETIME WORKER AT THE  AIR STRIPPING
FACILITY WOULD BE A FACTOR  OF APPROXIMATELY 0.16 TIMES THAT OF AN INDIVIDUAL EXPOSED CONTINUOUSLY  FOR A
70-YEAR LIFETIME TO  THE SAME AIRBORNE  CONCENTRATION; FOR A 2-YEAR WORKER THIS FACTOR WOULD  BE 0.0068.

       UPPER 95% CONFIDENCE LIMITS ON  ESTIMATED EXCESS CANCER RISKS ASSOCIATED WITH INHALATION EXPOSURE OF
WORKERS TO VINYL CHLORIDE AT THE AIR STRIPPING TOWERS OR AT A DISTANCE OF 100 METERS AND FOR  RESIDENTS AT A
DISTANCE OF 100 METERS WERE CALCULATED USING THE EPA-DERIVED CANCER POTENCY FACTOR FOR  THIS COMPOUND AND  THE
EXPOSURE ASSUMPTIONS NOTED  ABOVE.  THESE VALUES ARE SHOWN IN EXHIBIT 1 FOR THE TOWER OFF-GAS  OR AMBIENT
CONCENTRATIONS AND  EXPOSURE PERIODS  CONSIDERED.  EPA ENCOURAGES ELIMINATION OF CANCER RISKS TO INDIVIDUALS

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RESULTING FROM EXPOSURE AT  A SUPERFUND SITE WHERE THIS IS FEASIBLE.  HOWEVER, ACCORDING TO AGENCY POLICY, THE
TOTAL INDIVIDUAL CANCER RISK RESULTING FROM EXPOSURES MAY RANGE BETWEEN  10-4 TO  10-7  (I.E.,  ONE EXCESS CANCER
IN EVERY 10,000 AND  10,000,000  INDIVIDUALS, RESPECTIVELY, EXPOSED THROUGHOUT THEIR LIFETIME).   THUS,  AN
EXCESS CANCER RISK OF  10-6  IS COMMONLY USED AS AN APPROXIMATELY GUIDELINE  FOR DETERMINING AN ACCEPTABLE LEVEL
OF EXPOSURE WITHIN ONE OR TWO ORDERS OF MAGNITUDE.

       AS SHOWN IN EXHIBIT  1, THE  LIFETIME EXCESS CANCER RISKS ASSOCIATED WITH EXPOSURE TO VINYL CHLORIDE
UNDER THE PLAUSIBLE  MAXIMUM SCENARIOS CONSIDERED  (WORKER EXPOSURE AT THE AIR STRIPPING TOWERS)  RANGE FROM 9 X
10-6 TO 7 X 10-4.  FOR COMPARISON,  EXPOSURE TO VINYL CHLORIDE FOR A WORKING LIFETIME  (47 YEARS)  AT 0.9 UG/M3
OR FOR 2 YEARS AT 20 UG/M3  WOULD EACH BE ASSOCIATED WITH AN EXCESS CANCER  RISK OF  10-6.  THE AIR STRIPPING
TOWER OFF-GAS CONCENTRATIONS OF 610 AND 180 UG/M3 SHOWN IN EXHIBIT 1 ARE EACH LESS THAN THE OSHA AND ACGIH
WORKPLACE CRITERIA OF  2.6 AND 10 MG/M3,  RESPECTIVELY.

       LIFETIME EXCESS CANCER RISKS ASSOCIATED WITH OCCUPATIONAL OR CONTINUOUS AMBIENT  EXPOSURE TO VINYL
CHLORIDE AT CONCENTRATIONS  THAT COULD POTENTIALLY OCCUR AT A DISTANCE OF 100 METERS FROM THE AIR STRIPPING
TOWERS ARE LESS THAN OR EQUAL TO 10-6 UNDER ALL EXPOSURE SCENARIOS CONSIDERED.

                                    EXHIBIT 1

                  EXCESS CANCER RISKS ASSOCIATED WITH INHALATION
                       OF VINYL CHLORIDE EMISSIONS FROM THE
                          SACWSD AIR STRIPPING FACILITY

                                             EXCESS CANCER RISK A

   VINYL CHLORIDE
   CONCENTRATION                  LIFETIME EXPOSURE       2-YEAR EXPOSURE

   OCCUPATIONAL EXPOSURE B:
     AT AIR STRIPPING  TOWER:
       610 UG/M3                     7 X 10-4  (A)            3 X 10-5  (A)
       180 UG/M3                     2 X 10-4  (A)            9 X 10-6  (A)
     100 METERS FROM TOWER:
       0.155 UG/M3                   2 X 10-7  (A)            8 X 10-9  (A)
       0.046 UG/M3                   5 X 10-8  (A)            2 X 10-9  (A)

   AMBIENT EXPOSURE  C:
     100 METERS FROM TOWER:
       0.155 UG/M3                   1 X 10-6  (A)            3 X 10-8  (A)
       0.046 UG/M3                   3 X 10-7  (A)            9 X 10-9  (A)

   A VINYL CHLORIDE  IS CLASSIFIED IN EPA'S WEIGHT-OF-EVIDENCE FOR
     CARCINOGENICITY GROUP  A, MEANING IT IS CONSIDERED A HUMAN CARCINOGEN

   B ASSUMES EXPOSURE  8 HOURS/DAY,  5 DAYS/WEEK FOR A 47-YEAR  (WORKING
     LIFETIME) OR A  2-YEAR  PERIOD

   C ASSUMES CONTINUOUS EXPOSURE FOR A 70-YEAR LIFETIME OR FOR 2 YEARS.


                                 VINYL CHLORIDE

QUALITATIVE DESCRIPTION OF  HEALTH EFFECTS

VINYL CHLORIDE IS RAPIDLY ABSORBED IN RATS FOLLOWING INGESTION AND INHALATION  (EPA 1985A, B).  DERMAL
ABSORPTION OF VINYL  CHLORIDE IS MINOR (EPA 1980A) .  SIGNIFICANT PERCUTANEOUS ABSORPTION WOULD  NOT BE EXPECTED
TO OCCUR AT EXPOSURES  AT 1  OR 5 PPM (EPA 1980A) .  FOLLOWING INHALATION OR  INGESTION OF 14C-VINYL CHLORIDE IN
RATS, THE GREATEST AMOUNT OF RADIOACTIVITY WAS FOUND IN THE LIVER AND KIDNEY  (EPA  1985A,B).  IT ALSO
DISTRIBUTED TO THE MUSCLE,  LUNG,  FAT,  SPLEEN,  AND BRAIN  (EPA 1985A, B).   THE TOXICITY  OF VINYL  CHLORIDE
APPEARS TO BE ATTRIBUTABLE  TO ITS  METABOLISM IN THE LIVER TO REACTIVE POLAR METABOLITES SUCH AS
CHLOROACETALDEHYDE AND CHLOROETHYLENE OXIDE (EPA 1985A,B).  ITS METABOLISM TO TOXIC METABOLITES IS SATURABLE
(EPA 1985A,B) BETWEEN  105 AND 220  PPM (EPA 1985A,B).  AT HIGHER EXPOSURES  VINYL  CHLORIDE IS DETOXIFIED  (EPA
1985A, B).  AT LOW DOSES  (E.G.,  1 MG/KG)  OF VINYL CHLORIDE, THE METABOLITES ARE EXCRETED PRIMARILY IN THE
URINE (EPA 1985A, B).   IN RATS,  URINARY METABOLITES INCLUDE N-ACETYL-5-2-HYDROXYETHYLCYSTEINE AND
THIODIGLYCOLIC ACID  (EPA 1985A,B).  AT HIGH DOSES  (E.G., 100 MG/KG) MOST  OF THE SOLVENT IS EXPIRED AS VINYL
CHLORIDE  (EPA 1985A, B) .

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ACUTE/CHRONIC EFFECTS

AT HIGH INHALATION EXPOSURE LEVELS, WORKERS HAVE EXPERIENCED DIZZINESS, HEADACHES, EUPHORIA, AND NARCOSIS
(EPA 1985A, B). IN EXPERIMENTAL ANIMALS, INHALATION EXPOSURE TO HIGH LEVELS OF VINYL CHLORIDE CAN INDUCE
NARCOSIS AND DEATH (EPA 1985A, B) . LOWER DOSES RESULT IN ATAXIA, CONGESTION, AND EDEMA OF THE LUNGS AND
HYPEREMIA IN THE LIVER (EPA 1985A) .

CHRONIC INHALATION EXPOSURES OF WORKERS TO VINYL CHLORIDE IS ASSOCIATED WITH HEPATOTOXICITY, CENTRAL NERVOUS
SYSTEM DISTURBANCES, PULMONARY INSUFFICIENCY, CARDIOVASCULAR TOXICITY, GASTROINTESTINAL TOXICITY, AND
ACRO-OSTEOLYSIS (EPA 1985A, B). CHRONIC INHALATION AND ORAL STUDIES OF EXPERIMENTAL ANIMALS EXPOSED TO VINYL
CHLORIDE YIELD TOXIC EFFECTS SIMILAR TO THOSE SEEN IN HUMANS, INVOLVING THE LIVER, SPLEEN, KIDNEYS,
HEMATOPOIETIC SYSTEM, AND SKELETAL SYSTEM (EPA 1984A) .

TERATOGENICITY/REPRODUCTIVE EFFECTS

INHALATION EXPOSURES OF RATS, RABBITS, AND MICE TO VINYL CHLORIDE DID NOT INDUCE TERATOGENIC EFFECTS (EPA
1985A, B). POTENTIAL EFFECTS ON REPRODUCTIVE CAPACITY HAVE NOT BEEN STUDIES (EPA 1985A, B).

MUTAGENICITY

THE MUTAGENIC EFFECTS OF VINYL CHLORIDE HAVE BEEN DEMONSTRATED IN METABOLICALLY ACTIVATED SYSTEMS USING S.
TYPHIMURIUM, E. COLI, YEAST, GERM CELLS OF DROSOPHILIA, AND CHINESE HAMSTER V79 CELLS (EPA 1985A,B). VINYL
CHLORIDE WAS EFFECTIVE IN PRODUCING CHROMOSOME DAMAGE IN RAT BONE MARROW AFTER A MULTIPLE EXPOSURE REGIME
(EPA 1985A,B). CHROMOSOME ABERRATIONS IN HUMANS HAVE YIELDED INCONSISTENT RESULTS (EPA 1985A,B).

CARCINOGENICITY

THE ABILITY OF VINYL CHLORIDE TO ACT AS A CARCINOGEN IN THE INDUSTRIAL ENVIRONMENT WAS READILY ESTABLISHED
BECAUSE OF THE EXTREME RARITY IN EXPOSED POPULATIONS OF THE HEPATIC ANGIOSARCOMAS WITH WHICH IT IS ASSOCIATED
(IARC 1979). VINYL CHLORIDE EXPOSURE HAS ALSO BEEN IMPLICATED IN BRAIN, LUNG, AND HEMOLYMPHOPOIETIC CANCERS
IN HUMANS (IARC 1979). ANIMAL STUDIES IN SEVERAL SPECIES SUPPORT THE FINDINGS OF EPIDEMIOLOGICAL STUDIES.
CHRONIC INHALATION AND INGESTION OF VINYL CHLORIDE HAS INDUCED CANCER IN LIVER (LIVER ANGIOSARCOMAS AND
HEPATOCELLULAR CARCINOMAS) AND OTHER TISSUES IN RATS AND MICE (IARC 1979).

QUANTITATIVE DESCRIPTION OF HEALTH EFFECTS

APPLYING EPA'S CRITERIA FOR EVALUATING THE OVERALL WEIGHT OF EVIDENCE OF CARCINOGENICITY TO HUMANS, VINYL
CHLORIDE HAS BEEN CLASSIFIED IN GROUP A, MEANING THAT IT IS A HUMAN CARCINOGEN (EPA 1984A) .

EPA (1984A) REPORTED CARCINOGENIC POTENCIES (Ql*) FOR EXPOSURE BY INHALATION AND INGESTION TO VINYL CHLORIDE
IN ITS HEALTH EFFECTS ASSESSMENT (HEA) FOR THIS COMPOUND. THE Ql* FOR INHALATION IS BASED ON AN INHALATION
BIOASSAY IN RATS (MALTONI AND LEFEMINE 1985) . GROUPS OF 64 TO 96 SPRAGUE-DAWLEY RATS WERE EXPOSED TO VARIOUS
CONCENTRATIONS OF VINYL CHLORIDE FOR 4 HOURS A DAY, 5 DAYS A WEEK, FOR 52 WEEKS, AND THE SURVIVORS WERE
SACRIFICED AFTER 135 WEEKS. ANGIOSARCOMAS, PARTICULARLY OF THE LIVER, WERE THE PREDOMINANT TUMORS OBSERVED.
THE LINEARIZED MULTISTAGE MODEL WAS FITTED TO THE INCIDENCES OF MALE AND FEMALE RATS WITH ANY TYPE OF
MALIGNANT TUMOR (6/58, 10/59, 16/69, 22/59, AND 32/59 IN THE 0-, 50-, 250-, 500-, AND 2,500 PPM DOSE GROUPS,
RESPECTIVELY. THE 6,000- AND 10,000-PPM GROUPS WERE NOT INCLUDED IN THE FINAL FITTED MODEL BECAUSE THE TUMOR
INCIDENCE WAS SAID TO HAVE EFFECTIVELY PLATEAUED AT 51.7% AND 62.3%. USING THE LINEAR NONTHRESHOLD MODEL
ADOPTED BY THE EPA (1980B), THE DATA OF MALTONI AND LEFEMINE (1975), AND INTERSPECIES SCALING FACTORS, A
HUMAN Ql* OF 2.5 X 10-2 (MG/KG/DAY)-1 WAS CALCULATED.

THE Ql* FOR ORAL EXPOSURE TO VINYL CHLORIDE, AS REPORTED IN THE HEA FOR THIS COMPOUND, IS BASED ON A
LONG-TERM INGESTION STUDY IN RATS (FERON ET AL. 1981). GROUPS OF MALE AND FEMALE WISTAR RATS WERE EXPOSED TO
VINYL CHLORIDE VIA INGESTION OF POLYVINYL CHLORIDE POWDER CONTAINING SOME UNREACTED MONOMER. THE DOSES OF
VINYL CHLORIDE ADMINISTERED WERE 0, 1.7, 5.0, AND 14.1 MG/KG/DAY. DOSING WAS CONTINUED FOR LIFETIMES WITH
TERMINAL SACRIFICES AT 135 WEEKS FOR MALES AND AT 144 WEEKS FOR FEMALES. A SIGNIFICANT DOSE-RELATED INCREASE
IN THE INCIDENCE OF HEPATOCELLULAR CARCINOMAS AND HEPATIC ANGIOSARCOMAS WAS OBSERVED IN BOTH MALES AND
FEMALES, WITH ANGIOSARCOMAS BECOMING MORE PREVALENT WITH INCREASING DOSES. THE LINEARIZED MULTISTAGE MODEL
WAS FITTED TO THE INCIDENCES OF TOTAL FEMALE RATS WITH TUMORS (2/57, 26/58, 42/59, IN THE 0-, 1.7-, 5.0-, AND
14.1-MG/KG/DAY DOSE GROUPS, RESPECTIVELY). THE INCIDENCE OF HEPATOCELLULAR CARCINOMA WAS NOT INCLUDED IN
THESE TALLIES; IT WAS ASSUMED THAT RATS HAVING HEPATOCELLULAR CARCINOMA ALSO HAD HEPATIC NEOPLASTIC NODULES
WHICH WERE INCLUDED IN THE TALLIES. IN ADDITION, THE TOTAL NUMBER OF ANIMALS BEARING TUMORS IN THE HIGH DOSE
GROUP WAS ARBITRARILY REDUCED TO ONE LESS THAN THE TOTAL NUMBER OF ANIMALS EXAMINED, SO THE DATA WOULD FIT
THE LINEAR NON-THRESHOLD MODEL USED FOR ESTIMATION OF CARCINOGENIC POTENCY. USING THE DATA OF FERON ET AL.
(1981) AND INTERSPECIES SCALING FACTORS, A HUMAN Ql* OF 2.3 (MG/KG/DAY)-1 WAS CALCULATED. THE CONCENTRATION
IN DRINKING WATER CORRESPONDING TO A 10-6 EXCESS LIFETIME CANCER RISK IS 0.015 UG/LITER. * THE GAG IS
PRESENTLY REASSESSING THE CANCER RISK ESTIMATE BASED ON THE FERON ET AL. (1981) STUDY BY TAKING INTO ACCOUNT

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THE MORE RECENT DATA BY TIL ET AL. (1983) WHICH IS AN EXTENSION OF THE EARLIER FERON ET AL. (1981) WORK, BUT
INCLUDING LOWER DOSES.

EPA (1985C) PROMULGATED A DRINKING WATER RMCL OF ZERO, BECAUSE VINYL CHLORIDE IS A HUMAN CARCINOGEN. A
DRINKING WATER MCL OF 0.001 MG/LITER HAS BEEN PROPOSED (EPA 1985D).

THE EPA OFFICE OF DRINKING WATER DEVELOPED 10-DAY HEALTH ADVISORIES (HAS) OF 9.0 MG/LITER FOR AN ADULT AND
2.6 MG/LITER FOR A CHILD (EPA 1985A) . THE HAS WERE BASED ON A SUBCHRONIC STUDY IN WHICH VINYL CHLORIDE WAS
ADMINISTERED BY GAVAGE TO MALE AND FEMALE WISTAR RATS AT DOSES OF 31, 100 OR 300 MG/KG ONCE DAILY, 6 DAYS PER
WEEK FOR 13 WEEKS (FERON ET AL. 1975). SEVERAL HEMATOLOGICAL, BIOCHEMICAL, AND ORGAN WEIGHT VALUES WERE
SIGNIFICANTLY DIFFERENT IN BOTH MID- AND HIGH-DOSE ANIMALS COMPARED TO CONTROLS. THE NOAEL IN THIS STUDY WAS
IDENTIFIED AS 30 MG/KG.

AN ADJUSTED ADI OF 0.046 MG/LITER FOR NONCARCINOGENIC EFFECTS WAS CALCULATED USING AN ORAL FEEDING STUDY IN
RATS WHICH REPORTED THAT A DOSE OF 1.3 MG/KG/DAY PRODUCED LIVER LESIONS; A DOSE OF 0.13 MG/KG/DAY WAS
IDENTIFIED AS A NOAEL (TIL ET AL. 1983).

* THIS VALUE WAS SUMMARIZED AND INCLUDED IN THE RECOMMENDATIONS OF THE SUPERFUND PUBLIC HEALTH EVALUATION
MANUAL. EPA 540/1-86/060.
SUMMARY OF VINYL CHLORIDE CRITERIA

EPA CARCINOGEN CLASSIFICATION

ORAL CARCINOGENIC POTENCY FACTOR (Ql*)
GROUP A

2.3 (MG/KG/DAY)-1
INHALATION CARCINOGENIC POTENCY FACTOR (Ql*) 2.5 X 10-2 (MG/KG/DAY)-1

EPA DRINKING WATER HEALTH ADVISORIES (HA)
TEN-DAY HA:
ADULT
CHILD
9.0 MG/LITER
2 . 6 MG/LITER
FINAL RMCL

PROPOSED MCL
ZERO

0.001 MG/LITER
DRINKING WATER CONCENTRATION
CORRESPONDING TO 10-6 EXCESS
LIFETIME CANCER RISK
0.015 UG/LITER
AWQC (CONCENTRATION ASSOCIATED WITH
A 10-6 LIFETIME CANCER RISK)
INGESTION OF WATER AND AQUATIC
ORGANISMS
INGESTION OF WATER
2.0 UG/LITER
2.0 UG/LITER.

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REFERENCES

ENVIRONMENTAL PROTECTION AGENCY (EPA). 1980. AMBIENT WATER QUALITY CRITERIA FOR VINYL CHLORIDE. OFFICE OF
WATER REGULATIONS AND STANDARDS, CRITERIA AND STANDARDS DIVISION, WASHINGTON, D.C. OCTOBER 1980. EPA
440/5-80-078.

ENVIRONMENTAL PROTECTION AGENCY (EPA). 1984A. HEALTH EFFECTS ASSESSMENT FOR VINYL CHLORIDE. ENVIRONMENTAL
CRITERIA AND ASSESSMENT OFFICE. CINCINNATI, OHIO. SEPTEMBER 1984. EPA 540/1-86-036.

ENVIRONMENTAL PROTECTION AGENCY (EPA) . 1984B. PROPOSED GUIDELINES FOR CARCINOGEN RISK ASSESSMENT; REQUEST
FOR COMMENTS. FED. REG. 49:46294-46301 (NOVEMBER 23, 1984).

ENVIRONMENTAL PROTECTION AGENCY (EPA). 1985A. DRAFT HEALTH ADVISORY FOR VINYL CHLORIDE. OFFICE OF DRINKING
WATER. WASHINGTON, D.C. SEPTEMBER 30.

ENVIRONMENTAL PROTECTION AGENCY (EPA) . 1985B. FINAL DRAFT FOR THE DRINKING WATER CRITERIA DOCUMENT ON VINYL
CHLORIDE. OFFICE OF DRINKING WATER. WASHINGTON, D.C. JANUARY 1985.

ENVIRONMENTAL PROTECTION AGENCY (EPA) . 1985C. NATIONAL PRIMARY DRINKING WATER REGULATIONS; VOLATILE
SYNTHETIC ORGANIC CHEMICALS, FINAL RULE. FEDERAL REGISTER 50:46880-46901.

ENVIRONMENTAL PROTECTION AGENCY (EPA) . 1985D. NATIONAL PRIMARY DRINKING WATER REGULATIONS; VOLATILE
SYNTHETIC ORGANIC CHEMICALS, PROPOSED RULEMAKING. FED. REG. 46902-46933 (NOVEMBER 13, 1985).

FERONV.J., HENDRIKSEN, C.F.M., SPEEK, A.J., TIL, H.P., AND, SPIT, B.J. 1981. LIFESPAN ORAL TOXICITY STUDY
OF VINYL CHLORIDE IN RATS. FOOD COSMET. TOXICOL. 19:317-333.

INTERNATIONAL AGENCY FOR RESEARCH ON CANCER (IARC). 1979. IARC GRAPHS ON THE EVALUATION OF THE CARCINOGENIC
RISKS OF CHEMICALS TO HUMANS. VOL. 20: SOME HALOGENATED HYDROCARBONS. WORLD HEALTH ORGANIZATION,
LYON, FRANCE.

MALTONI, C., AND LEFEMINE, G. 1975. CARCINOGENICITY BIOASSAYS VINYL CHLORIDE. CURRENT RESULTS. ANN. NY
ACAD. SCI. 246:195-218.

TIL, H.P., IMMEL, H.R., AND FERON, V.J. 1983. LIFESPAN ORAL CARCINOGENICITY STUDY OF VINYL CHLORIDE IN
RATS. FINAL REPORT. CIVO INSTITUTES TNO REPORT NO. V 83 285/29109.

SUPERFUND PUBLIC HEALTH EVALUATION MANUAL. EPA 540/1-86/060, OCTOBER, 1986.

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                                      ATTACHMENT C
                                      TO APPENDIX A

                           ESTIMATED COSTS OF AIR STRIPPING

                                                  CAMP DRESSER & MCKEE INC.

MEMORANDUM

TO:       JOHN HOPKINS  -  DENVER

FROM:     STEWART ABRAMS  - EDISON

DATE:     FEBRUARY 5, 1987

PROJECT:  EPA CONTRACT  NO. 68-01-6939,  RMA OFF-POST RI/FS SITE

SUBJECT:  CONCEPTUAL SIZINGS:   VINYL CHLORIDE STRIPPING

DOCUMENT CONTROL NO.:   198-FS2-IO-DXTG-1

AS YOU REQUESTED, WE HAVE ANALYZED A RANGE OF SIZINGS TO REMOVE VINYL CHLORIDE FROM A  12 MGD  FLOWRATE.   WE
RECOMMEND THAT THE FLOW BE SPLIT,  AT A MINIMUM,  INTO TWO SEPARATE PARALLEL FLOWS.  THEREFORE,  THE  SIZINGS ARE
BASED ON 6 MGD.  WE HAVE  EVALUATED TWO SEPARATE TREATMENT OBJECTIVES:  1) 0.1 MCG/L, WHICH  ROUGHLY
CORRESPONDS TO THE LOWEST PRACTICAL ANALYTICAL DETECTION LIMIT, AND 2) 0.015 MCG/L, WHICH ROUGHLY  CORRESPONDS
TO THE 10-6 LIFETIME CANCER  RISK.   TWO RAW WATER CONCENTRATIONS HAVE BEEN EVALUATED FOR EACH  SCENARIO:   3
MCG/L AND 10 MCG/L.  WE HAVE ASSUMED THAT THE BACKGROUND WATER QUALITY PRESENTS NO UNUSUAL  INTERFERENCES TO
THE STRIPPING PROCESS.  THE  COSTS OF THE TOWERS INCLUDE CLEARWELL, PUMPS, TOWER AND INTERNALS, AND BLOWERS.
DESIGN ENGINEERING IS NOT INCLUDED NOR IS THE COST OF A BUILDING TO HOUSE THE FACILITIES, ACCESS ROADS,  OR
OTHER INDIRECT COSTS.   THEREFORE,  FOR EACH CASE THE FOLLOWING SIZINGS AND ROUGH CAPITAL COSTS APPLY:

        CASE 1:  RAW WATER       =3.0 MCG/L
                 FINISHED WATER =0.1 MCG/L

                 AT 6 MGD:   TOWER DIAMETER     = 12 FT
                             PACKING HEIGHT     = 18 FT
                             AIR-TO-WATER RATIO =20:1

                 COST:  2 TOWERS @ $401,000 EACH = $802,000

        CASE 2:  RAW WATER       =10 MCG/L
                 FINISHED WATER =0.1 MCG/L

                 AT 6 MGD:   TOWER DIAMETER     = 12 FT
                             PACKING HEIGHT     = 24 FT
                             AIR-TO-WATER RATIO =20:1

                 COST:  2 TOWERS @ $426,000 EACH = $852,000

        CASE 3:  RAW WATER       = 3 MCG/L
                 FINISHED WATER = 0.015 MCG/L

                 AT 6 MGD:   TOWER DIAMETER     = 12 FT
                             PACKING HEIGHT     = 28 FT
                             AIR-TO-WATER RATIO =20:1

                 COST:  2 TOWERS @ $481,000 EACH = $962,000

        CASE 4:  RAW WATER       =10 MCG/L
                 FINISHED WATER = 0.015 MCG/L

                 AT 6 MGD:   TOWER DIAMETER     = 12 FT
                             PACKING HEIGHT     = 33 FT
                             AIR-TO-WATER RATIO =20:1

                 COST:  2 TOWERS @ $516,000 EACH = $ 1,032,000.

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IN ALL CASES, IF THE  12 MGD  WERE TREATED IN A SINGLE TOWER, WE WOULD RECOMMEND  AN 18  FOOT DIAMETER.
OTHERWISE, PACKING HEIGHTS AND AIR-TO-WATER RATIOS WOULD REMAIN THE SAME.   COSTS  WOULD ALSO BE ABOUT THE SAME
MAGNITUDE.

IF YOU HAVE ANY QUESTIONS, OR REQUIRE FURTHER INFORMATION, PLEASE CALL.

SA/EBE

CC:  S. MEDLAR
     G. KROLL
     B. ROBERTS
     FILE

   (EBE36/7).

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APPENDIX B

APPLICABLE OR RELEVANT AND APPROPRIATE
STATE STANDARDS

THE STATE OF COLORADO PROVIDED THE AGENCY WITH "A LIST OF THE APPLICABLE OR RELEVANT AND APPROPRIATE
ON-POST AND OFF-POST STANDARDS, REQUIREMENTS, LIMITATIONS OR CRITERIA ("REQUIREMENTS OR STANDARDS") FOR THE
ROCKY MOUNTAIN ARSENAL" ON JANUARY 8, 1987. THE STATE AMENDED THIS LIST ON MARCH 17, 1987, TO DELETE SEVERAL
REQUIREMENTS AND ADD AN ADDITIONAL REQUIREMENT. THE STATE IDENTIFIED ALL APPLICABLE OR RELEVANT AND
APPROPRIATE STANDARDS (ARARS), NOT ONLY THOSE THAT ARE MORE STRINGENT THAN SIMILAR FEDERAL PROVISIONS. I/.

THE AGENCY HAS REVIEWED THE STATE'S SUBMITTAL UNDER THE CRITERIA OF SECTION 121(D)(2)(A)(II) OF
CERCLA, WHICH PROVIDES IN PERTINENT PART:

WITH RESPECT TO ANY HAZARDOUS SUBSTANCE, POLLUTANT OR CONTAMINANT THAT WILL REMAIN ONSITE, IF ...
ANY PROMULGATED STANDARD, REQUIREMENT CRITERIA, OR LIMITATION UNDER A STATE ENVIRONMENTAL OR
FACILITY SITING LAW THAT IS MORE STRINGENT THAN ANY FEDERAL STANDARD, REQUIREMENT, CRITERIA OR
LIMITATION ... IS LEGALLY APPLICABLE TO THE HAZARDOUS SUBSTANCE OR POLLUTANT OR CONTAMINANT
CONCERNED OR IS RELEVANT AND APPROPRIATE TO THE CIRCUMSTANCES OF THE RELEASE OR THREATENED RELEASE
OF SUCH HAZARDOUS SUBSTANCE OR POLLUTANT OR CONTAMINANT, THE REMEDIAL ACTION SELECTED UNDER SECTION
9604 ... SHALL REQUIRE, AT THE COMPLETION OF THE REMEDIAL ACTION, A LEVEL OR STANDARD OF CONTROL
FOR SUCH HAZARDOUS SUBSTANCE OR POLLUTANT OR CONTAMINANT WHICH AT LEAST ATTAINS SUCH LEGALLY
APPLICABLE OR RELEVANT AND APPROPRIATE STANDARD, REQUIREMENT CRITERIA OR LIMITATION.". (EMPHASIS
ADDED.).

IF A STATE REQUIREMENT THAT IS IDENTIFIED AS APPLICABLE OR RELEVANT AND APPROPRIATE IN THIS APPENDIX B
IS MORE STRINGENT THAN A FEDERAL REQUIREMENT, THE STATE REQUIREMENT IS THE APPLICABLE OR RELEVANT AND
APPROPRIATE REQUIREMENT TO BE ATTAINED FOR THIS OPERABLE UNIT. IF THE STATE AND FEDERAL REQUIREMENTS ARE
EQUIVALENT, EITHER THE STATE OR THE FEDERAL REQUIREMENT MUST BE ATTAINED. IF AN APPLICABLE OR RELEVANT AND
APPROPRIATE FEDERAL REQUIREMENT IS MORE STRINGENT THAN A STATE REQUIREMENT, THE FEDERAL REQUIREMENT IS THE
APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENT TO BE ATTAINED FOR THIS OPERABLE UNIT.

SECTION 121(D)(2)(C) OF CERCLA LIMITS THE APPLICABILITY OF STATE REQUIREMENTS OR SITING LAWS WHICH
COULD EFFECTIVELY RESULT IN THE STATEWIDE PROHIBITION OF LAND DISPOSAL OF HAZARDOUS SUBSTANCES, POLLUTANT, OR
CONTAMINANTS, UNLESS CERTAIN CONDITIONS ARE MET. SINCE THE PROPOSED DISPOSITION OF WASTE GENERATED BY OR
ASSOCIATED WITH ANY OF THE REMEDIAL ACTION ALTERNATIVES FOR THIS OPERABLE UNIT IS NOT LAND DISPOSAL, SECTION
121(D)(2)(C) IS NOT APPLICABLE, AND WAS NOT CONSIDERED BY THE AGENCY IN REVIEWING THE STATE'S PROPOSAL.

SECTION 121(D)(4)(E) OF CERCLA PROVIDES THE AGENCY WITH DISCRETION TO SELECT A REMEDIAL ACTION THAT
DOES NOT ATTAIN AN APPLICABLE OR RELEVANT AND APPROPRIATE STATE REQUIREMENT IF THE STATE HAS NOT CONSISTENTLY
APPLIED THE REQUIREMENT IN SIMILAR CIRCUMSTANCES AT OTHER REMEDIAL ACTIONS. THE AGENCY HAS NOT INVOKED THIS
DISCRETIONARY WAIVER WITH RESPECT TO ANY OF THE STATE'S PROPOSED ARARS. THE AGENCY HAS NOT MADE ANY
DETERMINATIONS, HOWEVER, AS TO WHETHER OR NOT THE STATE HAS CONSISTENTLY APPLIED THE REQUIREMENTS AT OTHER
SITES.

APPLICABLE OR RELEVANT AND APPROPRIATE STATE REQUIREMENTS ARE SUMMARIZED IN THE ATTACHMENT TO THIS
APPENDIX. 2/. IN THE EVENT THAT EPA HAS DETERMINED THAT A STATE REQUIREMENT IS NOT APPLICABLE OR RELEVANT
AND APPROPRIATE FOR THIS SPECIFIC OPERABLE UNIT, AN EXPLANATION IS PROVIDED.
I/ ALTHOUGH THE STATED PROPOSED ARARS FOR ON-POST AND OFF-POST OF THE ROCKY MOUNTAIN ARSENAL, THIS
ANALYSIS IS LIMITED STRICTLY TO THOSE REQUIREMENTS WHICH ARE APPLICABLE OR RELEVANT AND APPROPRIATE TO
THIS SPECIFIC OPERABLE UNIT. THIS ANALYSIS IS NOT INTENDED TO APPLY TO OR ESTABLISH ARARS FOR THE
ONGOING RI/FS WORK CURRENTLY BEING CONDUCTED BY THE ARMY AT RMA, AND IS NOT INTENDED TO ESTABLISH ANY
PRECEDENT FOR FUTURE REMEDIAL ACTIONS CONDUCTED ON-POST OR OFF-POST. ARARS MUST BE ESTABLISHED ON A
SITE SPECIFIC BASIS.

2/ A REQUIREMENT IS APPLICABLE IF IT WOULD APPLY TO THE REMEDIAL ACTION IF THE REMEDIAL ACTION WERE
UNDERTAKEN OUTSIDE OF CERCLA AUTHORITY. A REQUIREMENT IS RELEVANT AND APPROPRIATE IF, EVEN THOUGH NOT
APPLICABLE, IT IS DESIGNED TO APPLY TO PROBLEMS OR SITUATIONS SUFFICIENTLY SIMILAR TO THOSE
ENCOUNTERED AT THE SITE THAT ITS APPLICATION IS APPROPRIATE. REQUIREMENTS MAY BE RELEVANT AND
APPROPRIATE IF THEY WOULD BE APPLICABLE BUT FOR THE JURISDICTIONAL RESTRICTIONS ASSOCIATED WITH THE
REQUIREMENT.

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                               ATTACHMENT TO APPENDIX B

      APPLICABLE OR RELEVANT AND APPROPRIATE STATE  STANDARDS,  REQUIREMENTS,
         LIMITATIONS AND CRITERIA FOR THE EPA OFF-POST  RI/FS SITE FIRST
                                   OPERABLE UNIT

I.  GENERAL COMMENTS

       A.  ENFORCEMENT PROVISIONS

         THE STATE HAS LISTED NUMEROUS ENFORCEMENT  PROVISIONS  AS  ARARS FOR THIS OPERABLE UNIT.  SEE E.G.,
         C.R.S. SECTIONS 30-20-113  (ENFORCEMENT-CIVIL PENALTIES); 30-20-114 (VIOLATION-PENALTY); 25-15-110
         (SITE DEEMED PUBLIC NUISANCE - WHEN);  25-15-211  (VIOLATION-CRIMINAL PENALTIES); 25-15-212
         (VIOLATION-CIVIL PENALTIES); 25-15-308  (PROHIBITED ACTS-ENFORCEMENT);25-15-309 (CIVIL PENALTIES);
         25-15-310 (CRIMINAL PENALTIES); 25-8-601  (DIVISION TO BE NOTIFIED OF SUSPECTED VIOLATIONS AND
         ACCIDENTAL DISCHARGES-PENALTY); 25-8-605  (CASE AND DESIST ORDERS); 25-8-606 (CLEAN-UP ORDER);
         25-8-607  (RESTRAINING ORDER AND INJUNCTION); 25-8-608 (CIVIL PENALTIES); 25-8-609  (CRIMINAL
         POLLUTION OF STATE WATERS-PENALTY); 25-1-114 AND  114.1 (UNLAWFUL TO DISOBEY PUBLIC HEALTH LAWS AND
         CIVIL PENALTIES; 25-1-107(X) (III) (B)  (WARRANTS FOR INSPECTION);  25-7-115 (ENFORCEMENT); 25-7-121
         (INJUNCTIONS); 25-7-122  (CIVIL PENALTIES);  25-12-104  (ACTION TO  ABATE);  25-12-105  (VIOLATION OF
         INJUNCTION - PENALTY); 33-6-103  (PROSECUTION OF OFFENSES);  33-6-104 (IMPOSITION OF
         PENALTY-PROCEDURES); 33-6-106  (SUSPENSION  OF LICENSE  PRIVILEGES); AND 33-6-107 (LICENSING
         VIOLATIONS-PENALTIES).

         SUCH ENFORCEMENT PROVISIONS ARE NOT STANDARDS, REQUIREMENTS,  CRITERIA OR LIMITATIONS UNDER STATE
         ENVIRONMENTAL OR FACILITY SITING LAWS  THAT ARE LEGALLY APPLICABLE TO THE HAZARDOUS SUBSTANCES,
         POLLUTANTS OR CONTAMINANTS  OF CONCERN  OR RELEVANT AND APPROPRIATE UNDER THE CIRCUMSTANCES OF THE
         RELEASE OR THREATENED RELEASE OF SUCH  HAZARDOUS SUBSTANCE OR POLLUTANT OR CONTAMINANT, AS REQUIRED
         BY SECTION 121(D)(2)(A)(II) OF CERCLA.  RATHER, THE PROVISIONS PROVIDE THE MECHANISMS BY WHICH STATE
         REGULATORY AGENCIES MAY ENFORCE SUBSTANTIVE ENVIRONMENTAL OR FACILITY SITING LAWS WHICH MAY BE ARARS
         FOR A PARTICULAR REMEDIAL ACTION.

         SECTION 121 (D) (2) (A) (II) PROVIDES THAT SELECTED REMEDIAL ACTIONS MUST REQUIRE, AT THE COMPLETION OF
         REMEDIAL ACTION, A LEVEL OR STANDARD OF CONTROL FOR HAZARDOUS SUBSTANCES OR POLLUTANTS OR
         CONTAMINANTS OF CONCERN WHICH AT LEAST ATTAINS LEGALLY APPLICABLE OR RELEVANT AND APPROPRIATE
         STANDARDS, REQUIREMENTS, CRITERIA OR LIMITATIONS.   THE ENFORCEMENT PROVISIONS DO NOT CONTAIN
         ENVIRONMENTAL OR FACILITY SITING REQUIREMENTS  WHICH DESCRIBE,  SPECIFY, REQUIRE OR OTHERWISE PROVIDE
         FOR A DEGREE OF CLEANUP WHICH THE REMEDY MUST  AT  LEAST ATTAIN, NOR DO THEY DESCRIBE, SPECIFY,
         REQUIRE OR OTHERWISE PROVIDE FOR LEVELS OR STANDARDS  OF  CONTROL   (SUCH AS THOSE CONTAINED IN, BUT NOT
         LIMITED TO,  AMBIENT OR CHEMICAL SPECIFIC REQUIREMENTS, LOCATIONAL REQUIREMENTS, OR PERFORMANCE
         DESIGN OR OTHER ACTION-SPECIFIC REQUIREMENTS)  FOR THE HAZARDOUS  SUBSTANCES OR POLLUTANTS OR
         CONTAMINANTS OF CONCERN FOR THIS OPERABLE  UNIT.

         THEREFORE, EPA HAS CONCLUDED THAT THE  ENFORCEMENT PROVISIONS CONTAINED IN THE STATE'S JANUARY 8,
         1987 LIST OF ARARS ARE NOT  ARARS FOR THIS  OPERABLE UNIT.  WHILE  THE ENFORCEMENT PROVISIONS ARE NOT
         ARARS UNDER SECTION 121(D)(2)(A)(II) OF CERCLA, THE STATE NEVERTHELESS MAY ASSERT SUCH ENFORCEMENT
         PROVISIONS TO THE EXTENT PROVIDED FOR  BY LAW,  IN  INSTANCES OF ALLEGED NON-COMPLIANCE.

       B.  PERMITTING REQUIREMENTS

         THE STATE HAS LISTED SEVERAL PERMITTING REQUIREMENTS,  OR THE INFORMATION SUBMITTALS, NOTIFICATION
         REQUIREMENTS, MONITORING, FEES, DATA COLLECTION,  AND  DATA REPORTING REQUIREMENTS CONTAINED WITHIN
         SUCH PERMITTING REQUIREMENTS, AS ARARS FOR THIS OPERABLE UNIT.  SEE E.G., C.R.S.  SECTIONS 30-20-102
         (UNLAWFUL TO OPERATE SITE AND FACILITY WITHOUT CERTIFICATE OF DESIGNATION); 30-20-103  (APPLICATION
         FOR CERTIFICATE); 25-15-202 (APPLICATION FOR CERTIFICATE);  25-8-501(3) AND (5) (PERMITS REQUIRED FOR
         DISCHARGE OF POLLUTANTS); 25-8-503(1)  (PERMITS -  WHEN REQUIRED AND WHEN PROHIBITED); 25-8-502
         (APPLICATION-DEFINITIONS-FEES-WATER QUALITY CONTROL FUND);  25-7-114 (AIR POLLUTION EMISSION NOTICES
         AND EMISSION PERMITS; AND IMPLEMENTING REGULATIONS.   SEE ALSO 6  CCR 1007-3 PART 100.

         EPA IS NOT DETERMINING AT THIS TIME WHETHER THE SELECTED REMEDY  FOR THIS OPERABLE UNIT IS AN ON-SITE
         OR OFFSITE RESPONSE ACTIONS.  UNDER SECTION 121 (E)  OF CERCLA,  NO FEDERAL, STATE OR LOCAL PERMIT IS
         REQUIRED FOR THE PORTION OF ANY REMEDIAL ACTION CONDUCTED ENTIRELY ON-SITE, WHERE SUCH REMEDIAL
         ACTION IS SELECTED AND CARRIED OUT IN  COMPLIANCE  WITH SECTION 121.  CONVERSELY, PERMITS WILL BE
         OBTAINED FOR ANY PORTION OF REMEDIAL ACTION CONDUCTED OFFSITE.

-------
         REGARDLESS OF WHETHER THE SELECTED  REMEDIAL ACTION IS CHARACTERIZED AS AN ON-SITE OR OFFSITE
         RESPONSE, THE SUBSTANTIVE PROVISIONS  OF  APPLICABLE OR RELEVANT AND APPROPRIATE PERMIT REQUIREMENTS
         (FOR EXAMPLE, ENVIRONMENTAL CRITERIA  UNDER WHICH A PERMIT IS REVIEWED, OR MONITORING REQUIREMENTS
         AND DATA COLLECTION REQUIREMENTS  TO DETERMINE WHETHER SUBSTANTIVE ENVIRONMENTAL REQUIREMENTS ARE
         BEING ATTAINED) ARE ARARS.  SUBSTANTIVE  REQUIREMENTS GENERALLY INCLUDE, BUT ARE NOT LIMITED TO,
         PROMULGATED STANDARDS, REQUIREMENTS,  CRITERIA OR LIMITATIONS UNDER A STATE ENVIRONMENTAL OR FACILITY
         SITING LAW WHICH DESCRIBE, SPECIFY, REQUIRE OR OTHERWISE PROVIDE FOR A DEGREE OF CLEANUP WHICH THE
         REMEDY MUST AT LEAST ATTAIN, OR WHICH DESCRIBE,  SPECIFY, REQUIRE OR OTHERWISE PROVIDE FOR LEVELS OR
         STANDARDS OF CONTROL FOR THE HAZARDOUS SUBSTANCES OR POLLUTANTS OR CONTAMINANTS OF CONCERN FOR THIS
         OPERABLE UNIT.  THE APPLICABLE OR RELEVANT AND APPROPRIATE SUBSTANTIVE PERMIT REQUIREMENTS ARE
         DISCUSSED BELOW IN SECTION II, SPECIFIC  PROVISIONS.

         INFORMATION SUBMITTALS, NOTIFICATIONS, FEE PROVISIONS,  AND DATA REPORTING REQUIREMENTS CONTAINED IN
         PERMIT REQUIREMENTS ARE NOT SUBSTANTIVE  REQUIREMENTS OF STATE ENVIRONMENTAL OR FACILITY SITING
         LAWS.  WHILE THE AGENCY DOES NOT  CONSIDER SUCH INFORMATION  SUBMITTALS, NOTIFICATIONS, FEE
         PROVISIONS, AND DATA REPORTING REQUIREMENTS TO BE ARARS FOR THIS OPERABLE UNIT, THE AGENCY WILL
         MAINTAIN CLOSE CONSULTATION WITH  APPROPRIATE STATE REPRESENTATIVES TO ENSURE THAT THE STATE IS
         PROVIDED WITH ALL RELEVANT TECHNICAL  DATA,  REPORTS,  NOTIFICATIONS, AND OTHER INFORMATION NECESSARY
         FOR EFFECTIVE IMPLEMENTATION OF THE REMEDY.  IN MOST CASES,  THIS MEANS THAT THE STATE WILL RECEIVE
         AT LEAST AS MUCH TIMELY INFORMATION,  NOTICE,  AND DATA AS IT WOULD IF THE REQUIREMENTS WERE
         APPLICABLE OR RELEVANT AND APPROPRIATE UNDER SECTION 121 (D) (2) (A) (II)  OF CERCLA.  ALSO, AS
         PREVIOUSLY NOTED, PERMITS WILL BE OBTAINED FOR THE PORTION OF ANY REMEDIAL ACTION CONDUCTED OFFSITE.

         IN THE EVENT THAT ANY HAZARDOUS SUBSTANCE OR POLLUTANT OR CONTAMINANT IS TRANSFERRED OFFSITE FROM
         THE TREATMENT FACILITY, SUCH HAZARDOUS SUBSTANCE OR POLLUTANT OR CONTAMINANT SHALL ONLY BE
         TRANSFERRED TO A FACILITY WHICH IS  OPERATING IN COMPLIANCE WITH SECTION 3004 AND 3005 OF THE SOLID
         WASTE DISPOSAL ACT IN ACCORDANCE  WITH SECTION 121(D)(3)  OF SARA, OR EQUIVALENT OR MORE STRINGENT
         STATE REQUIREMENTS.

       C.  LEGISLATIVE DECLARATIONS AND DEFINITIONS

         LEGISLATIVE DECLARATION PROVISIONS  GENERALLY DO NOT CONTAIN SUBSTANTIVE REQUIREMENTS OF STATE
         ENVIRONMENTAL OR FACILITY SITING  LAWS PURSUANT TO SECTION 121(D)(2)(A)(II) OF CERCLA *, AND ARE
         THEREFORE NOT APPLICABLE OR RELEVANT  AND APPROPRIATE REQUIREMENTS. THE AGENCY WILL MAINTAIN CLOSE
         CONSULTATION WITH APPROPRIATE STATE REPRESENTATIVES TO ENSURE THAT STATE CONCERNS AND LEGISLATIVE
         INTENT ARE ADDRESSED.  IN THE EVENT A LEGISLATIVE DECLARATION CONTAINED SUBSTANTIVE REQUIREMENTS, IT
         WOULD BE EVALUATED TO DETERMINE WHETHER  IT IS A RELEVANT AND APPROPRIATE REQUIREMENT.

         DEFINITIONAL PROVISIONS GENERALLY CONTAIN SUBSTANTIVE REQUIREMENTS OR DIRECTLY IMPACT THE SCOPE OR
         APPLICABILITY OF OTHER SUBSTANTIVE  REQUIREMENTS.  DEFINITIONAL PROVISIONS GENERALLY ARE CONSIDERED
         ARARS FOR THIS OPERABLE UNIT UNLESS OTHERWISE NOTED.

       D.  SCOPE OF SPECIFIC PROVISIONS DISCUSSION

         THE SPECIFIC PROVISIONS DISCUSSION  WHICH FOLLOWS ADDRESSES ONLY THE COLORADO REQUIREMENTS
         SPECIFICALLY LISTED BY THE STATE  IN ITS  JANUARY 8,  1987, AND MARCH 17, 1987, LETTERS TO EPA.  OTHER
         REQUIREMENTS NOT SPECIFICALLY LISTED  BY  THE STATE,  BUT CONTAINED WITHIN THE REFERENCED STATUTES OR
         REGULATIONS HAVE NOT BEEN EVALUATED.

       * FOR PURPOSES OF APPENDIX B AND THIS ATTACHMENT,  SUBSTANTIVE REQUIREMENTS INCLUDE, BUT ARE NOT
         LIMITED TO, PROMULGATED STANDARDS,  REQUIREMENTS, CRITERIA, OR LIMITATIONS UNDER A STATE
         ENVIRONMENTAL OR FACILITY SITING  LAW  WHICH DESCRIBE,  SPECIFY, REQUIRE OR OTHERWISE PROVIDE FOR A
         DEGREE OF CLEANUP WHICH THE REMEDY  FOR THIS OPERABLE UNIT MUST AT LEAST ATTAIN, OR WHICH DESCRIBE,
         SPECIFY, REQUIRE OR OTHERWISE PROVIDE FOR LEVELS OR STANDARDS OF CONTROL FOR THE HAZARDOUS
         SUBSTANCES, POLLUTANTS OR CONTAMINANTS OF CONCERN FOR THIS OPERABLE UNIT.  SEE SECTION
         121 (D) (2) (A) (II) OF CERCLA.

II.  SPECIFIC PROVISIONS

      A. COLORADO SOLID WASTES DISPOSAL SITES  AND FACILITIES ACT, SECTIONS 30-20-101 TO 30-20-118, C.R.S.
         1986.

      - NOT APPLICABLE OR RELEVANT AND APPROPRIATE - DESIGN,  CONSTRUCTION AND/OR OPERATION OF A SOLID WASTE
        DISPOSAL SITE ARE NOT CONTEMPLATED AS  POTENTIAL REMEDIES FOR THIS OPERABLE UNIT.  IF SOLID WASTE IS
        GENERATED AS PART OF THE REMEDY  (NOT CONTEMPLATED CURRENTLY,)  SUCH WASTE SHALL BE DISPOSED OF AT AN
        APPROVED SOLID WASTE DISPOSAL SITE OR  FACILITY IN ACCORDANCE WITH THE REQUIREMENTS OF THE ACT AND
        PERTINENT REGULATIONS.

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B. COLORADO SOLID WASTES DISPOSAL SITES AND FACILITIES REGULATIONS 6 CCR 1007-2, SECTIONS 1.1 - 7.3

- NOT APPLICABLE OR RELEVANT AND APPROPRIATE - DESIGN, CONSTRUCTION AND/OR OPERATION OF A SOLID WASTE
DISPOSAL SITE ARE NOT CONTEMPLATED AS POTENTIAL REMEDIES FOR THIS OPERABLE UNIT. IF SOLID WASTE IS
GENERATED AS PART OF THE REMEDY (NOT CONTEMPLATED CURRENTLY,) SUCH WASTE SHALL BE DISPOSED OF AT AN
APPROVED SOLID WASTE DISPOSAL SITE OR FACILITY IN ACCORDANCE WITH THE REQUIREMENTS OF THE ACT AND
PERTINENT REGULATIONS.

C. COLORADO HAZARDOUS WASTE ACT, C.R.S. SS25-15-101 TO 313.

- APPLICABLE TO THE EXTENT THE SELECTED ALTERNATIVE INVOLVES THE GENERATION, TRANSPORTATION, TREATMENT,
OR STORAGE OF HAZARDOUS WASTES. THE SPENT GRANULAR ACTIVATED CARBON FROM THE GAG TREATMENT SYSTEM
MAY CONTAIN HAZARDOUS WASTES REGULATED UNDER THE COLORADO HAZARDOUS WASTE ACT AND IMPLEMENTING
REGULATIONS. THE SELECTED REMEDY DOES NOT CONTEMPLATE DISPOSAL OF HAZARDOUS WASTES.

- THE FOLLOWING REQUIREMENTS SPECIFICALLY LISTED BY THE STATE ARE NOT ARARS, SINCE THEY ARE NOT
SUBSTANTIVE REQUIREMENTS OF STATE ENVIRONMENTAL OR FACILITY SITING LAWS PURSUANT TO SECTION
121(D) (2) (A) (II) OF CERCLA: C.R.S. SS25-15-102, 103, 200.2, 208, 215, 301, 302 (2) (3) (4), AND 304.

D. RULES AND REGULATIONS PERTAINING TO SOLID AND HAZARDOUS WASTES, PART 2, REQUIREMENTS FOR SITING OF
HAZARDOUS WASTE DISPOSAL SITES

- NOT APPLICABLE OR RELEVANT AND APPROPRIATE. THE SELECTED REMEDY DOES NOT CONTEMPLATE SITING OF A
HAZARDOUS WASTE DISPOSAL SITE, OR DISPOSAL OF HAZARDOUS WASTE.

E. COLORADO HAZARDOUS WASTE REGULATIONS, 6 CCR 1007-3, PARTS 260 TO 267, 99 AND 100.

THE SELECTED ALTERNATIVE, GRANULAR ACTIVATED CARBON TREATMENT OF THE GROUNDWATER WITH INCINERATION
OF VOLATILE ORGANIC COMPOUNDS ADSORBED ON THE CARBON, MAY GENERATE HAZARDOUS WASTE (HAZARDOUS WASTE
ADSORBED IN CARBON) WHICH MAY BE STORED TEMPORARILY OR TRANSPORTED TO AN APPROVED FACILITY FOR
INCINERATION AND REGENERATION OF THE CARBON. THE FOLLOWING PROVISIONS ARE APPLICABLE TO SUCH
HAZARDOUS WASTES:

PART 260 - HAZARDOUS WASTE MANAGEMENT SYSTEM: GENERAL

PART 261 - IDENTIFICATION AND LISTING OF HAZARDOUS WASTES

PART 262 - STANDARDS APPLICABLE TO GENERATORS OF HAZARDOUS WASTE. NOTE: SUBPART E, SPECIAL
CONDITIONS, INTERNATIONAL SHIPMENTS AND FARMERS IS NOT APPLICABLE OR RELEVANT AND
APPROPRIATE. THE SELECTED REMEDY DOES NOT CONTEMPLATE SUCH CIRCUMSTANCES.

PART 263 - STANDARDS APPLICABLE TO TRANSPORTERS OF HAZARDOUS WASTE. NOTE: IF HAZARDOUS WASTE IS
TRANSPORTED OUTSIDE OF THE STATE OF COLORADO, THE REQUIREMENTS OF 40 CFR PART 263, OR
EQUIVALENT OR MORE STRINGENT STATE REQUIREMENTS, ARE APPLICABLE.

PART 264 - STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE AND DISPOSAL
FACILITIES

- SUBPARTS A-H ARE APPLICABLE

- SUBPART I IS APPLICABLE IF THE SELECTED REMEDY INVOLVES STORAGE OF HAZARDOUS WASTES IN
CONTAINERS

- SUBPART J IS APPLICABLE IF THE SELECTED REMEDY INVOLVES USE OF TANKS TO STORE HAZARDOUS
WASTES

- SUBPART K IS APPLICABLE IF THE SELECTED REMEDY INVOLVES THE USE OF SURFACE IMPOUNDMENTS
TO STORE HAZARDOUS WASTES

- SUBPART L IS APPLICABLE IF THE SELECTED REMEDY INVOLVES STORAGE OF HAZARDOUS WASTES IN
PILES

- SUBPART M IS NOT APPLICABLE OR RELEVANT AND APPROPRIATE SINCE LAND TREATMENT OF ANY
HAZARDOUS WASTES IS NOT CONTEMPLATED AS PART OF THE REMEDY FOR THIS OPERABLE UNIT

- SUBPART N IS NOT APPLICABLE OR RELEVANT AND APPROPRIATE SINCE THE REMEDY DOES NOT
CONTEMPLATE DISPOSAL OF HAZARDOUS WASTES IN A LANDFILL

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- SUBPART 0 IS APPLICABLE IN THE EVENT INCINERATION OF THE SPENT CARBON OCCURS WITHIN THE
STATE. IF INCINERATION OF SPENT CARBON OCCURS OUTSIDE OF THE STATE OF COLORADO, THE
REQUIREMENTS OF 40 CFR PART 264, SUBPART 0, OR EQUIVALENT OR MORE STRINGENT STATE
REQUIREMENTS, ARE APPLICABLE.

- APPENDICES 1-6 ARE APPLICABLE TO THE EXTENT THEY CONTAIN SUBSTANTIVE REQUIREMENTS.

THE FOLLOWING REQUIREMENTS ARE NOT APPLICABLE OR RELEVANT AND APPROPRIATE:

PART 265 INTERIM STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE, AND
DISPOSAL FACILITIES

- INTERIM STANDARDS DO NOT APPLY TO NEW STORAGE FACILITIES; REMEDIES SHOULD COMPLY WITH THE
MORE STRINGENT PART 264 STANDARDS AS THESE REPRESENT THE ULTIMATE RCRA COMPLIANCE STANDARDS
AND ARE CONSISTENT WITH CERCLA'S GOALS OF LONGTERM PROTECTION OF PUBLIC HEALTH AND THE
ENVIRONMENT.

PART 267 INTERIM STANDARDS FOR OWNERS AND OPERATORS OF NEW HAZARDOUS WASTE LAND DISPOSAL FACILITIES

- REMEDY DOES NOT CONTEMPLATE LAND DISPOSAL OF HAZARDOUS WASTE

PART 99 NOTIFICATION

- ALTHOUGH THE PART 99 NOTIFICATION PROVISION IS NOT A SUBSTANTIVE REQUIREMENT, THE AGENCY WILL
MAINTAIN CLOSE CONSULTATION WITH APPROPRIATE STATE REPRESENTATIVES TO ENSURE THAT THE STATE
RECEIVES TIMELY NOTIFICATION OF HAZARDOUS WASTE ACTIVITIES IN ACCORDANCE WITH THE TERMS OF
PART 99.

PART 100 PERMIT REQUIREMENTS

- SEE SECTION I(B), GENERAL COMMENTS, PERMITTING REQUIREMENTS. THE SUBSTANTIVE REQUIREMENTS
WITHIN PART 100 ARE APPLICABLE OR RELEVANT AND APPROPRIATE. THE AGENCY WILL MAINTAIN CLOSE
CONSULTATION WITH APPROPRIATE STATE REPRESENTATIVES TO ENSURE THEIR CONCERNS ARE ADDRESSED.

- SECTIONS 100.13, 100.30, 100.31, 100.34, AND 100.61(B) DO NOT CONTAIN SUBSTANTIVE PROVISIONS
AND ARE NOT ARARS. SECTION 100.20 IS NOT APPLICABLE OR RELEVANT AND APPROPRIATE SINCE AN
INTERIM STATUS PERMIT IS NOT CONTEMPLATED AS PART OF THE REMEDY.

- PERMITS WILL BE OBTAINED FOR THE PORTION OF THE REMEDIAL ACTION INVOLVING ANY OFF-SITE
HAZARDOUS WASTE ACTIVITY.

F. COLORADO WATER QUALITY CONTROL ACT, C.R.S. SECTIONS 25-8-501 TO 25-8-612

- NOT APPLICABLE OR RELEVANT AND APPROPRIATE. NO DISCHARGE OF POLLUTANTS THROUGH POINT SOURCES OR
NON-POINT SOURCES TO WATERS OF THE STATE OF COLORADO IS CONTEMPLATED AS A REMEDY FOR THIS
OPERABLE UNIT. IF THERE IS A DISCHARGE OF POLLUTANTS INTO WATERS OF THE STATE RESULTING FROM THE
REMEDIAL ACTION (NOT CONTEMPLATED), SUCH DISCHARGE ONLY MAY OCCUR IN ACCORDANCE WITH THE
REQUIREMENTS OF THE COLORADO WATER QUALITY CONTROL ACT AND PERTINENT REGULATIONS.

G. STATE DISCHARGE PERMIT SYSTEM REGULATIONS, 5 CCR 1002-2, SECTIONS 6.1.0 TO 6.18

- NOT APPLICABLE OR RELEVANT AND APPROPRIATE. NO DISCHARGE OF POLLUTANTS THROUGH POINT SOURCE TO
WATERS OF THE STATE OF COLORADO IS CONTEMPLATED AS A REMEDY FOR THIS OPERABLE UNIT. IF SUCH A
DISCHARGE OCCURS OR IS CONTEMPLATED, THESE REGULATIONS ARE APPLICABLE OR RELEVANT AND APPROPRIATE.
SEE SECTION I(B), GENERAL COMMENTS, PERMITTING REQUIREMENTS.

H. EFFLUENT LIMITATIONS, 5 CCR 1002-3, SECTIONS 10.1.1 TO 10.1.7

- NOT APPLICABLE OR RELEVANT AND APPROPRIATE. NO DISCHARGE OF WASTEWATER INTO STATE WATERS IS
CONTEMPLATED AS A REMEDY FOR THIS OPERABLE UNIT. IF SUCH A DISCHARGE OCCURS OR IS CONTEMPLATED,
THESE EFFLUENT LIMITATIONS ARE APPLICABLE OR RELEVANT AND APPROPRIATE.

I. SEWAGE AND STORM SEWERS, 5 CCR 1002-7, SECTIONS 5.1 TO 5.2

- NOT APPLICABLE OR RELEVANT AND APPROPRIATE. NO DISCHARGE OF WASTEWATER TO STORM SEWERS OR
PROHIBITED CONNECTIONS TO STORM SEWERS ARE CONTEMPLATED AS A REMEDY FOR THIS OPERABLE UNIT. IF
SUCH A DISCHARGE OCCURS OR IS CONTEMPLATED, THESE PROVISIONS WOULD BE APPLICABLE OR RELEVANT AND

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APPROPRIATE.

J. BASIC STANDARDS AND METHODOLOGIES, 5 CCR 1002-8, SECTIONS 3.1.1 TO 3.11.9

- NOT APPLICABLE OR RELEVANT AND APPROPRIATE. NO DISCHARGE TO WATERS OF THE STATE IS CONTEMPLATED
UNDER THIS OPERABLE UNIT, NOR DOES THIS OPERABLE UNIT ADDRESS REMEDIATION OF SURFACE WATER OR THE
UNDERLYING AQUIFER WITHIN THE EPA OFF-POST RI/FS SITE.

K. SITE APPLICATIONS FOR DOMESTIC WASTEWATER TREATMENT WORKS, 5 CCR 1002-12, SECTIONS 2.2.1 TO 2.2.7

- NOT APPLICABLE OR RELEVANT AND APPROPRIATE. NO CONSTRUCTION OF DOMESTIC WASTEWATER TREATMENT
WORKS IS CONTEMPLATED AS A REMEDY FOR THIS OPERABLE UNIT.

L. COLORADO SAFE DRINKING WATER AUTHORITIES - C.R.S. SS25-1-107(X), (Y); 25-1-114 AND 25-1-114.1

- GENERALLY, NOT APPLICABLE OR RELEVANT AND APPROPRIATE. THE CITED PROVISIONS ARE NOT SUBSTANTIVE
REQUIREMENTS. THE AGENCY WILL CONSULT WITH APPROPRIATE STATE REPRESENTATIVES REGARDING ANY
NOTIFICATION REQUIREMENTS TO ENSURE EFFECTIVE IMPLEMENTATION OF THE REMEDY. IF SUBSTANTIVE
REQUIREMENTS ARE IDENTIFIED, THEY WILL BE EVALUATED TO DETERMINE WHETHER THEY ARE APPLICABLE OR
RELEVANT AND APPROPRIATE.

M. COLORADO PRIMARY DRINKING WATER REGULATIONS, 5 CCR 1003-1, ARTICLES 1, 2, 4, 5, 6, 7, 8.

- APPLICABLE OR RELEVANT AND APPROPRIATE TO THE DRINKING WATER THAT WILL BE SUPPLIED TO THE PUBLIC
THROUGH THE SELECTED REMEDY, FOR CONTAMINANTS IDENTIFIED IN THE GROUNDWATER WHICH SUPPLIES THE
SOUTH ADAMS COUNTY WATER AND SANITATION DISTRICT ("SACWSD") SUPPLY WELLS.

N. COLORADO AIR QUALITY CONTROL REGULATIONS

- THE AIR STRIPPING ALTERNATIVES WOULD INVOLVE EMISSIONS OF POLLUTANTS TO THE ATMOSPHERE. FOR
REMEDIES THAT INVOLVE AIR STRIPPING, THE COLORADO AIR QUALITY CONTROL REGULATIONS MAY BE
APPLICABLE OR RELEVANT AND APPROPRIATE REGARDLESS OF WHICH REMEDY IS SELECTED. THE REGULATIONS
ARE DISCUSSED BELOW:

- COMMON PROVISIONS REGULATION, 5 CCR 1001-2 - APPLICABLE OR RELEVANT AND APPROPRIATE.

- REGULATION NO. 1, 5 CCR 1001-3, EMISSION CONTROL REGULATIONS FOR PARTICULATES, SMOKES, CARBON
MONOXIDE, AND SULFUR OXIDES.

A. ALTHOUGH NO EMISSIONS OF THESE CONTAMINANTS ARE CONTEMPLATED AS PART OF THE OPERATION OF THE
REMEDY, FUGITIVE PARTICULATES MAY BE GENERATED DURING THE CONSTRUCTION OF THE REMEDY. SECTION
III(D), FUGITIVE PARTICULATE EMISSIONS, IS APPLICABLE IF THE JURISDICTIONAL PREREQUISITES ARE
SATISFIED, OR RELEVANT AND APPROPRIATE IF SUCH PREREQUISITES ARE NOT MET. IF PARTICULATES,
SMOKES, CARBON MONOXIDE, OR SULFUR OXIDE ARE EMITTED AS A RESULT OF CONSTRUCTING OR
IMPLEMENTING THE REMEDY (NOT CONTEMPLATED) THEN OTHER SECTIONS OF REGULATION NO. 1 ADDRESSING
THESE POLLUTANTS WILL BE APPLICABLE OR RELEVANT AND APPROPRIATE.

- REGULATION NO. 2, 5 CCR 1001-4, ODOR EMISSION REGULATIONS - APPLICABLE

- REGULATION NO. 3, 5 CCR 1001-5, AIR CONTAMINANT EMISSION NOTICES, EMISSION PERMITS AND FEES, PSD
REGULATIONS.

A. SEE SECTION I(B), GENERAL COMMENTS, PERMITTING REQUIREMENTS. THE SUBSTANTIVE REQUIREMENTS
WITHIN THE PERMIT SECTIONS ARE APPLICABLE OR RELEVANT AND APPROPRIATE. THE AGENCY WILL
MAINTAIN CLOSE CONSULTATION WITH APPROPRIATE STATE REPRESENTATIVES TO ENSURE THEIR CONCERNS ARE
ADDRESSED.

B. THE PREVENTION OF SIGNIFICANT DETERIORATION (PSD) REGULATIONS ARE NOT APPLICABLE OR RELEVANT
AND APPROPRIATE. NONE OF THE REMEDIES CONTEMPLATED FOR THIS OPERABLE UNIT INVOLVE FACILITIES
ADDRESSED BY THE PSD REGULATIONS.

C. ALTHOUGH THE EMISSION NOTICES PROVISION IS NOT AN ARAR, THE AGENCY WILL MAINTAIN CLOSE
CONSULTATION WITH APPROPRIATE STATE REPRESENTATIVES TO ENSURE THAT THE STATE RECEIVES TIMELY
NOTIFICATION.

D. THE FEE PROVISIONS ARE NOT ARARS.

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- REGULATION NO. 6, 5 CCR 1001-8, PART A, SECTIONS I, III, IX, AND XIII, PART B, SECTIONS I, II AND
IV, NEW SOURCE PERFORMANCE STANDARDS

A. NOT APPLICABLE OR RELEVANT AND APPROPRIATE. THE SELECTED REMEDY CONTEMPLATED FOR THIS OPERABLE
UNIT WOULD NOT INVOLVE FACILITIES IN ANY OF THESE CATEGORIES.

- REGULATION NO. 7, 5 CCR 1001-9, VOLATILE ORGANIC COMPOUNDS

A. APPLICABLE OR RELEVANT AND APPROPRIATE IF THE SELECTED REMEDY WOULD INVOLVE THE STORAGE,
TRANSFER OR DISPOSAL OF VOLATILE ORGANICS, PETROLEUM OPERATIONS, USE OF SOLVENTS OR CUTBACK
ASPHALT OR SURFACE COATING OPERATIONS.

- REGULATION NO. 8, 5 CCR 1001-10, CONTROL OF HAZARDOUS AIR POLLUTANTS,

A. RELEVANT AND APPROPRIATE IF THE SELECTED REMEDY INVOLVES EMISSIONS OF VINYL CHLORIDE OR BENZENE
TO THE ATMOSPHERE.

- AMBIENT AIR QUALITY STANDARDS, 5 CCR 1001-14

A. NO EMISSIONS OF POLLUTANTS FOR WHICH AMBIENT AIR QUALITY STANDARDS HAVE BEEN ESTABLISHED ARE
CONTEMPLATED AS PART OF THE SELECTED REMEDY FOR THIS OPERABLE UNIT. (IF AN AIR STRIPPER IS
REQUIRED FOR THE TREATMENT OF VINYL CHLORIDE, SMALL AMOUNTS OF VOCS MAY BE RELEASED TO THE
ATMOSPHERE AND CONTRIBUTE TO OZONE FORMATION. THE OZONE STANDARD IS RELEVANT AND APPROPRIATE
TO THE CONTEMPLATED REMEDIAL ACTION FOR THIS OPERABLE UNIT IF EMISSIONS FROM AIR STRIPPING WILL
CONTRIBUTE TO THE FORMATION OF OZONE. ALSO, THE TOTAL SUSPENDED PARTICULATE (TSP) STANDARD IS
RELEVANT AND APPROPRIATE IN THE EVENT FUGITIVE PARTICULATE EMISSIONS RESULT FROM THE
CONSTRUCTION OF THE CONTEMPLATED REMEDY.).

0. COLORADO AIR QUALITY CONTROL ACT, SECTIONS 25-7-101 TO 25-7-505

- THE SPECIFIC PROVISIONS IDENTIFIED BY THE STATE DO NOT CONTAIN SUBSTANTIVE REQUIREMENTS AND ARE
GENERALLY NOT APPLICABLE OR RELEVANT AND APPROPRIATE. IF SUBSTANTIVE REQUIREMENTS ARE IDENTIFIED,
SUCH REQUIREMENTS WILL BE EVALUATED TO DETERMINE WHETHER THEY APPLY.

- THE AGENCY WILL MAINTAIN CLOSE CONSULTATION WITH APPROPRIATE STATE REPRESENTATIVES TO ENSURE THAT
THE STATE RECEIVES TIMELY NOTIFICATION IN ACCORDANCE WITH C.R.S. SS25-7-114 (2) AND (3).

- SECTION 123, INCINERATORS AND OPEN BURNING - NOT APPLICABLE OR RELEVANT AND APPROPRIATE. THE
ACTIVITIES REGULATED BY THIS PROVISION ARE NOT CONTEMPLATED IN THE SELECTED REMEDY FOR THIS
OPERABLE UNIT. IF THESE ACTIVITIES OCCUR (NOT CONTEMPLATED) THIS SECTION WILL BE APPLICABLE.

- SECTION 25-7-114 PROVIDES FOR EMISSION PERMITS. SEE SECTION I(B), GENERAL COMMENTS, PERMITTING
REQUIREMENTS. THE SUBSTANTIVE REQUIREMENTS OF THIS SECTION ARE APPLICABLE OR RELEVANT AND
APPROPRIATE. THE AGENCY WILL MAINTAIN CLOSE CONSULTATION WITH APPROPRIATE STATE REPRESENTATIVES
TO ENSURE THEIR CONCERNS ARE ADDRESSED.

- SECTIONS 25-7-501, 502, AND 504. NOT APPLICABLE OR RELEVANT AND APPROPRIATE. NONE OF THE
REMEDIES CONTEMPLATED FOR THIS OPERABLE UNIT INVOLVE ASBESTOS CONTROL.

P. COLORADO NOISE ABATEMENT STATUTE, SECTIONS 25-12-101 TO 25-12-108

- SECTIONS 25-12-102 (DEFINITIONS) AND 25-12-103 (MAXIMUM PERMISSIBLE NOISE LEVELS) ARE APPLICABLE
REQUIREMENTS OR RELEVANT AND APPROPRIATE REQUIREMENTS. THE OTHER SPECIFICALLY CITED PROVISIONS DO
NOT CONTAIN SUBSTANTIVE REQUIREMENTS AND ARE NOT APPLICABLE OR RELEVANT AND APPROPRIATE.

Q. WILDLIFE, C.R.S. SECTIONS 33-1-101 TO 33-1-120

- SECTION 33-1-101 (SHORT TITLE) DOES NOT CONTAIN SUBSTANTIVE REQUIREMENTS AND IS NOT APPLICABLE OR
RELEVANT AND APPROPRIATE.

- SECTION 33-1-102 (DEFINITIONS) IS APPLICABLE OR RELEVANT AND APPROPRIATE.

- SECTION 33-1-106 (MANAGEMENT) IS APPLICABLE IF ANY OF THE SELECTED REMEDIES INVOLVE THE TAKING,
POSSESSION, TRANSPORTATION, EXPORTATION, SHIPMENT, REMOVAL, CAPTURE OR DESTRUCTION OF WILDLIFE
WHICH APPEAR ON THE STATE'S LIST OF ENDANGERED OR THREATENED SPECIES. IT SHOULD BE NOTED THAT
NONE OF THE PROPOSED ALTERNATIVES CONTEMPLATE ANY OF THE ABOVE-LISTED ACTIVITIES FOR WILDLIFE.

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- SEE SECTION I(B), GENERAL COMMENTS, PERMITTING REQUIREMENTS. THE AGENCY WILL MAINTAIN CLOSE
CONSULTATION WITH APPROPRIATE STATE REPRESENTATIVES TO ENSURE THEIR CONCERNS ARE ADDRESSED.

R. WILDLIFE ENFORCEMENT AND PENALTIES, C.R.S. SS33-6-101 TO 33-6-130.

- GENERALLY, THE SPECIFICALLY CITED PROVISIONS ARE NOT APPLICABLE OR RELEVANT AND APPROPRIATE. SEE
DISCUSSION ON ENFORCEMENT PROVISIONS, P. 1 OF THIS ATTACHMENT. SECTIONS 33-6-109 (WILDLIFE -
ILLEGAL POSSESSION), 33-6-114 (TRANSPORTATION, IMPORTATION, EXPORTATION AND RELEASE OF WILDLIFE),
AND 33-6-120 (HUNTING, TRAPPING OR FISHING OUT OF SEASON OR IN A CLOSED AREA) ARE APPLICABLE OR
RELEVANT AND APPROPRIATE TO THE EXTENT THEY CONTAIN SUBSTANTIVE REQUIREMENTS. IT SHOULD BE NOTED
THAT THE SELECTED REMEDY DOES NOT CONTEMPLATE ANY ACTIVITIES COVERED OR PROHIBITED BY THESE
PROVISIONS.

- SEE SECTION I(B), GENERAL COMMENTS, PERMITTING REQUIREMENTS. THE AGENCY WILL MAINTAIN CLOSE
CONSULTATION WITH APPROPRIATE STATE REPRESENTATIVES TO ENSURE THEIR CONCERNS ARE ADDRESSED.

S. GENERAL PROVISIONS OF THE DIVISION OF WILDLIFE REGULATIONS, 2 CCR 406-0, ARTICLE II.

- SEE SECTION I(B), GENERAL COMMENTS, PERMITTING REQUIREMENTS.

- SUBSTANTIVE REQUIREMENTS CONTAINED WITHIN THESE REGULATIONS ARE APPLICABLE OR RELEVANT AND
APPROPRIATE. THE AGENCY WILL MAINTAIN CLOSE CONSULTATION WITH APPROPRIATE STATE REPRESENTATIVES
TO ENSURE THEIR CONCERNS ARE ADDRESSED. THE SELECTED REMEDY DOES NOT CONTEMPLATE ANY ACTIVITIES
DESCRIBED BY OR PROHIBITED BY THESE REGULATIONS.

T. THE WATER WELL AND PUMP INSTALLATION CONTRACTORS ACT, C.R.S. SS37-91-101 TO 37-91-112

- GENERALLY, THE ACT DOES NOT CONTAIN SUBSTANTIVE REQUIREMENTS AND IS NOT APPLICABLE OR RELEVANT AND
APPROPRIATE. SECTION 37-91-110 (BASIC STANDARDS AND MINIMUM STANDARDS) CONTAINS SUBSTANTIVE
REQUIREMENTS AND IS APPLICABLE OR RELEVANT AND APPROPRIATE TO PUMP INSTALLATION. THE SELECTED
REMEDY DOES NOT CONTEMPLATE CONSTRUCTION OF WATER WELLS.

- SEE SECTION I(B), GENERAL COMMENTS, PERMITTING REQUIREMENTS. THE AGENCY WILL MAINTAIN CLOSE
CONSULTATION WITH APPROPRIATE STATE REPRESENTATIVES TO ENSURE THEIR CONCERNS ARE ADDRESSED.

U. WATER WELL AND PUMP INSTALLATION CONTRACTORS REGULATIONS, 2 CCR 402-2

- SEE SECTION I(B), GENERAL COMMENTS, PERMITTING REQUIREMENTS.

- THE SUBSTANTIVE REQUIREMENTS CONTAINED WITHIN THE REGULATIONS ARE APPLICABLE OR RELEVANT AND
APPROPRIATE TO PUMP INSTALLATION. THE SELECTED REMEDY DOES NOT CONTEMPLATE CONSTRUCTION OF WATER
WELLS. THE AGENCY WILL MAINTAIN CLOSE CONSULTATION WITH APPROPRIATE STATE REPRESENTATIVES TO
ENSURE THEIR CONCERNS ARE ADDRESSED.

V. HISTORICAL, PREHISTORICAL AND ARCHAEOLOGICAL RESOURCES ACT, C.R.S. SS24-80-401 ET SEQ.

- APPLICABLE OR RELEVANT AND APPROPRIATE IF THE SELECTED REMEDY INVOLVES THE INVESTIGATION,
EXCAVATION, GATHERING, OR REMOVAL FROM THE NATURAL STATE OF ANY HISTORICAL, PREHISTORICAL AND
ARCHAEOLOGICAL RESOURCES WITHIN THE STATE.

- SEE SECTION I(B), GENERAL COMMENTS, PERMITTING REQUIREMENTS. THE AGENCY WILL MAINTAIN CLOSE
CONSULTATION WITH APPROPRIATE STATE REPRESENTATIVES TO ENSURE THEIR CONCERNS ARE ADDRESSED.

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APPENDIX C

STATE OF COLORADO AND SACWSD
CONCURRENCES WITH REMEDY

STATE OF COLORADO
COLORADO DEPARTMENT OF HEALTH

MAY 22, 1987

MR. JAMES SCHERER
REGIONAL ADMINISTRATOR
U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION VIII
ONE DENVER PLACE
999 18TH STREET, SUITE 500
DENVER, COLORADO 80202-2405

RE: EPA'S RMA OFF-POST FIRST OPERABLE UNIT APPROVED FINAL DRAFT RECORD
OF DECISION (ROD) - SOUTH ADAMS COUNTY DRINKING WATER TREATMENT SYSTEM

DEAR MR. SCHERER:

THE STATE OF COLORADO HAS REVIEWED THE MAY 14, 1987 APPROVED FINAL DRAFT ROD FOR EPA'S RMA OFF-POST FIRST
OPERABLE UNIT. THE STATE CONCURS WITH THE SELECTION OF A GRANULAR ACTIVATED CARBON (GAG) WATER TREATMENT
SYSTEM AS THE APPROPRIATE REMEDY FOR TREATMENT OF THE CONTAMINATED GROUND WATER WITHIN THE EPA OFF-POST RI/FS
SITE PRIOR TO ITS USE AS DRINKING WATER BY CUSTOMERS OF THE SOUTH ADAMS COUNTY WATER AND SANITATION DISTRICT
(SACWSD) .

WHILE THE STATE CONCURS WITH THE SELECTION OF THE GAG WATER TREATMENT SYSTEM AS THE PERMANENT REMEDY, OUR
CONCURRENCE WITH THE ROD IS CONDITIONED UPON THE FOLLOWING:

1) TO DATE, INSUFFICIENT FINANCING EXISTS TO COMPLETE THE CONSTRUCTION AND OPERATION OF THE GAG
TREATMENT SYSTEM. THEREFORE, IT MAY BE NECESSARY TO UTILIZE HAZARDOUS SUBSTANCE RESPONSE TRUST
FUND MONEY TO IMPLEMENT THE FINAL REMEDY. HOWEVER, THE U.S. ARMY HAS BEEN IDENTIFIED AS AT LEAST
ONE PARTY RESPONSIBLE FOR THE CONTAMINATION OF THE DRINKING WATER SUPPLY. AN INVESTIGATION OF
OTHER POTENTIALLY RESPONSIBLE PARTIES (PRPS) IS IN PROGRESS. GIVEN THAT LIABILITY UNDER CERCLA
IS JOINT AND SEVERAL, THE STATE'S POSITION IS THAT THE IDENTIFIED RESPONSIBLE PARTY(S) SHOULD
PROVIDE THE FULL COSTS OF IMPLEMENTING THE PERMANENT REMEDY, INCLUDING OPERATION AND
MAINTENANCE COSTS.

IN THE EVENT FUND MONEY IS UTILIZED TO IMPLEMENT THE REMEDY, CERCLA SECTION 104 (C) (3) REQUIRES
THAT THE STATE ENTER INTO A CONTRACT OR COOPERATIVE AGREEMENT WITH THE PRESIDENT PROVIDING
ADEQUATE ASSURANCES THAT THE STATE WILL PAY OR ASSURE PAYMENT OF 10% OF THE CAPITAL COSTS AND
ALL FUTURE COSTS FOR OPERATION AND MAINTENANCE FOR THE EXPECTED LIFE OF THE REMEDIAL ACTION.
HOWEVER, PURSUANT TO THE CURRENT STATE SUPERFUND ACT, SECTION 25-16-101, ET SEQ., C.R.S., THE
STATE CANNOT MAKE SUCH ASSURANCES UNLESS THE SITE HAS BEEN LISTED ON THE NATIONAL PRIORITIES
LIST (NPL). SEE SECTION 25-16-104.6(2)(B). AT THIS TIME, NEITHER THE ROCKY MOUNTAIN ARSENAL
NOR EPA'S RMA OFF-POST RI/FS SITE HAS BEEN FINALLY LISTED ON THE NPL.

SECTION 25-16-103(2) CURRENTLY STATES THAT, "ANY STATE MATCHING PAYMENT REQUIRED BY A
COOPERATIVE AGREEMENT ENTERED INTO PURSUANT TO THIS SECTION MUST BE APPROVED BY THE GENERAL
ASSEMBLY ACTING BY BILL.". FOR THESE REASONS, THE STATE CANNOT MAKE THE 104 (C) (3) 10% COST
ASSURANCE FOR CONSTRUCTION OF THE PERMANENT TREATMENT PLANT, OR THE ASSURANCE FOR ALL FUTURE
OPERATION AND MAINTENANCE COSTS, AT THIS TIME.

2) THE STATE STRONGLY OBJECTS TO THE CONCLUSION IN THE ROD THAT THE APPLICABLE OR RELEVANT AND
APPROPRIATE REQUIREMENTS (ARARS) FOR THIS OPERABLE UNIT ARE THE FINAL OR PROPOSED MAXIMUM
CONTAMINANT LEVELS (MCLS) ESTABLISHED UNDER THE SAFE DRINKING WATER ACT FOR ALL CONTAMINANTS
IDENTIFIED IN SOUTH ADAMS COUNTY DRINKING WATER. THIS CONCLUSION DEVIATES FROM THE SECTION
121(D) SUPERFUND AMENDMENTS AND REAUTHORIZATION ACT (SARA) PROVISION THAT THE "REMEDIAL ACTION
REQUIRE A LEVEL OR STANDARD OF CONTROL WHICH AT LEAST ATTAINS MAXIMUM CONTAMINANT LEVEL GOALS
(MCLGS) ESTABLISHED UNDER THE SAFE DRINKING WATER ACT. . .".

THIS CONCLUSION ALSO DEVIATES FROM THE MARCH 27, 1987 LETTER TO EPA ADMINISTRATOR LEE THOMAS
FROM THE CONFEREES INVOLVED IN THE CERCLA REAUTHORIZATION PROCESS. THE LETTER WAS WRITTEN "TO

-------
ADVISE YOU (LEE THOMAS) OF THE REQUIREMENTS OF SECTION 121 (OF SARA) AND THE INTENT BEHIND
THEM, . . .". THE LETTER ALSO STATES THAT, "(T)HE SPECIFIC REFERENCE TO MCLG'S IN THE LAW
MAKES IT CLEAR THAT THESE PARTICULAR STANDARDS, WHERE THEY ARE MORE STRINGENT THAN THE
COMPARABLE MCL'S, ARE THE PRIMARY STANDARDS UNDER THE SAFE DRINKING WATER ACT THAT MUST BE
ATTAINED BY SUPERFUND CLEANUPS OF GROUNDWATER, . . .". THE SOURCE OF SACWSD'S DRINKING WATER
IS GROUNDWATER. THEREFORE, PURSUANT TO STATUTORY REQUIREMENT, UNLESS THE EPA DETERMINES THAT
COMPLIANCE WITH MCLGS IS TECHNICALLY IMPRACTICABLE FROM AN ENGINEERING PERSPECTIVE, MCLGS ARE
THE ARARS AND MUST BE ATTAINED. SECTION 121 (D) (4) (C) , SARA.

AS YOU ARE AWARE, MCLS ARE OFTEN ESTABLISHED BASED UPON THE ANALYTIC DETECTION LIMITS RATHER
THAN ON HEALTH BASED CRITERIA. WHILE THE STATE DOES NOT AGREE WITH THE USE OF MCLS AS ARARS,
IF MCLS ARE TO BE USED AS ARARS, A SAFETY FACTOR MUST BE INCORPORATED WHICH APPROXIMATES THE
10-6 CANCER ASSESSMENT GROUP (GAG) CANCER RISK VALUE. FOR EXAMPLE, WITH TRICHLOROETHYLENE
(TCE), ONE MAJOR CONTAMINANT OF CONCERN AT THIS OPERABLE UNIT, THE 10-6 GAG NUMBER IS
APPROXIMATELY 2 UG/L LOWER THAN THE MCL. THEREFORE, A CRITERIA THAT INCORPORATES AN
OPERATIONAL SAFETY FACTOR BASED UPON A HEALTH RELATED STANDARD SHOULD BE USED AS THE ARAR.

THE EPA HAS DETERMINED THAT OTHER APPLICABLE OR RELEVANT AND APPROPRIATE STANDARDS,
REQUIREMENTS, CRITERIA OR LIMITATIONS (ARARS) IDENTIFIED BY THE STATE OF COLORADO ARE NOT
APPLICABLE OR RELEVANT AND APPROPRIATE TO THIS REMEDIAL ACTION. THERE ARE MANY INSTANCES WHERE
THE STATE DISAGREES WITH THIS DETERMINATION.

TO EXPEDITE IMPLEMENTATION OF THE REMEDY FOR THIS OPERABLE UNIT, THE STATE CONCURS WITH THE SELECTION OF THE
GAG WATER TREATMENT SYSTEM. HOWEVER, WE FEEL IT IS NECESSARY TO MEET WITH YOU TO DISCUSS AND ATTEMPT TO
RESOLVE THE ISSUES OUTLINED ABOVE AT YOUR EARLIEST CONVENIENCE. THE STATE LOOKS FORWARD TO WORKING CLOSELY
WITH YOU TO COMPLETE CONSTRUCTION OF THE SACWSD PERMANENT WATER TREATMENT SYSTEM TO PROTECT THE HEALTH AND
WELFARE OF THE CITIZENS OF COLORADO.

SINCERELY,

THOMAS P. LOOBY
ASSISTANT DIRECTOR
COLORADO DEPARTMENT OF HEALTH

TLP/CS:ME

CC: HOWARD KENISON, DEPUTY ATTORNEY GENERAL
ROBERT LAWRENCE, U.S. EPA
LARRY FORD, SACWSD
DAVE BROWN, ESQ.
CITIZENS AGAINST CONTAMINATION
SENATOR STRICKLAND
SENATOR MARTINEZ
REPRESENTATIVE BLESDOE
REPRESENTATIVE REESER
REPRESENTATIVE HUME
JOEL KOHN.

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                                            SO.  ADAMS COUNTY WATER
                                            AND SANITATION DISTRICT

MAY 18, 1987

MR. ROBERT L. DUPREY
U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION VIII
999 EIGHTEENTH STREET,  SUITE  500
DENVER, CO 80202-2405                   BY HAND-DELIVERY

RE:  FINAL DRAFT RECORD OF  DECISION ("ROD")  FOR
     FIRST OPERABLE UNIT, EPA'S RMA OFF-POST RI-FS SITE;
     DOCUMENT NO. 198-FS2-RT-ENBC-1

DEAR MR. DUPREY:

SOUTH ADAMS COUNTY WATER AND  SANITATION DISTRICT HAS BEEN CONSULTED BY EPA WITH REGARD  TO  THE
ABOVE-REFERENCED ROD.   NOW  THAT THE ROD HAS BEEN REVIEWED BY THE DISTRICT'S STAFF AND CONSULTANTS,  I  AM
AUTHORIZED BY THE BOARD OF  DIRECTORS OF THE DISTRICT TO INFORM YOU THAT THE DISTRICT CONCURS WITH THE
SELECTED REMEDY SET FORTH IN  THE  ROD.

WE LOOK FORWARD TO WORKING  CLOSELY WITH EPA IN IMPLEMENTING THIS NEXT, AND MOST IMPORTANT,  MILESTONE  FOR THE
PROTECTION OF OUR CUSTOMERS.

SINCERELY,

SOUTH ADAMS COUNTY WATER
AND SANITATION DISTRICT

BY:
     JEAN KLEIN, PRESIDENT

CC:  MR. CONNALLY MEARS
     HON. HANK BROWN
     PATRICIA L. BOHM,  ESQ.
     MR. RANDALL J. KRUEGER
     LYSLE R. DIRRIM, ESQ.
     DAVID M. BROWN, ESQ.

-------
                                  TABIiE A
                          FINAL AND PROPOSED MCLS
   PROPOSED MCLS FOR VOLATILE
   SYNTHETIC ORGANIC CHEMICALS  (A)

                                MG/L
FINAL MCLS FOR ORGANIC
AND INORGANIC CHEMICALS  (B)

                      MG/L
ORGANIC
                                        INORGANIC
TRICHLOROETHYLENE  (TCE)
CARBON TETRACHLORIDE
VINYL CHLORIDE
1,2-DICHLOROETHANE
1,1,1-TRICHLOROETHANE  (TCA)
P-DICHLOROBENZENE  (C)
BENZENE
1,1 DICHLOROETHYLENE
0.005
0.005
0.001
0.005
0.200
0.005
0.005
0.007


ARSENIC
BARIUM
CADMIUM
CHROMIUM
FLUORIDE
LEAD
MERCURY
NITRATE (AS N)
SELENIUM
SILVER
0.05
1
0.010
0.05
4.0
0.05
0.002
10
0.01
0.05
                                         ORGANIC
                      MG/L
                                         CHLORINATED HYDROCARBONS:
                                           ENDRIN                 0.0002
                                           LINDANE                 0.004
                                           METHOXYCHLOR              0.1
                                           TOXAPHENE               0.005
                                         CHLOROPHENOXYS:
                                           2,4-D
                                           2,4,5-TP SILVEX
                        0.1
                       0.01
                                         TOTAL TRIHALOMETHANES
                                                                    0.10
 (A) SEE 50 FED. REG.  46902  (NOV.  13,  1985)
 (B) SEE 40 CFR PART  141,  SUBPART  B
 (C) SEE 52 FED. REG.  12878  (APRIL 17,  1987).

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                                  TABIiE 1

                         ROCKY MOUNTAIN ARSENAL
                         EPA OFF-POST RI/FS SITE

            FREQUENTLY REPORTED  CHEMICALS DETECTED IN RECENT
            CLP-VALIDATED ANALYTICAL RESULTS FOR GROUND WATER
               MONITORING WELLS  IN THE OFF-POST STUDY AREA

                               MAXIMUM REPORTED
                                 CONCENTRATION
                               MARCH - JULY 1986     STANDARD/ADVISORY
   CHEMICAL                       (UG/LITER)              (UG/LITER)

1,1-DICHLOROETHANE                    14 (A)                 4000  (D)
1,1-DICHLOROETHYLENE                  11                       7  (B)
TRANS-1,2-DICHLOROETHYLENE            16                      70  (E)
1,1,1-TRICHLOROETHANE                 58                     200  (B)
TRICHLOROETHYLENE                    120                       5  (B)
TETRACHLOROETHYLENE                   21                     0.7  (C)

(A)  THIS VALUE IS AN ESTIMATED QUANTITY BECAUSE QUALITY CONTROL CRITERIA
    WERE NOT MET. HIGHEST REPORTED UNQUALIFIED VALUE IS 6 UG/LITER

(B)  MCL OR PROPOSED MCL

(C)  NO PROMULGATED OR PROPOSED MCL,  THEREFORE, THE REFERENCE
    CONCENTRATION FOR POTENTIAL  CARCINOGENS (AT A 10-6 RISK LEVEL) IS SHOWN

(D)  THERE IS NO MCL OR REFERENCE CONCENTRATION DEVELOPED TO DATE FOR
    POTENTIAL CARCINOGENS.  THEREFORE,  AN EPA HEALTH EFFECTS ASSESSMENT
    LEVEL FOR LIFETIME EXPOSURE  IS SHOWN

(E)  THERE IS NO MCL OR REFERENCE CONCENTRATION DEVELOPED TO DATE FOR
    POTENTIAL CARCINOGENS.  THEREFORE,  AN EPA HEALTH ADVISORY LEVEL FOR
    LIFETIME EXPOSURE IS SHOWN

SOURCE:  REPORT OF GROUNDWATER ANALYSES — ADAMS COUNTY WELLS  (COM 1986  A,B,E)

-------
                                 TABIiE  2
          OTHER DETECTED TENTATIVELY  IDENTIFIED  ORGANIC COMPOUNDS
ABBREVIATION  (A)
                            COMPOUND
                                           CAS  #
     MECL
     ACET
     CCL4
     TOL
     VYCL
     CLRF
     2DCA
     DIMP
     XYL
     ETHB
     CLB
     DCP
     2TCA
     MXYL
     OXYL

     BUT
     FLOR
     PHL
     PNAN
     PHTH
     BBPH
     DEPH
     DBPH
     NAP
     MNAP
     DPHL
     HETH
     DFRN
     BPH
     ANIL
     CNAP
     2DCB
     3DCB
     4DCB
     DBCP
     DIAZ
     ABHC
     DDT
     24D
     TP
     ODD
     HPEP
     ALDN
     ISDN
     ENDN
     DLDN
     DDE
     EDSF
     ETPR
 METHYLENE CHLORIDE
 ACETONE
 CARBON TETRACHLORIDE
 TOLUENE
 VINYL CHLORIDE
 CHLOROFORM
 1,2 DCA
 DIMP
 TOTAL XYLENES
 ETHYL BENZENE
 CHLOROBENZENE
 1,2 DICHLOROPROPANE
 1,1,2 TCA
 M-XYLENE
 0,P-XYLENE

 2-BUTANONE
 FLUORENE
 PHENOL
 PHENANTHRENE
 PHTHALATE
 BUTYLBENZYLPHTHALATE
 DIETHYL PHTHALATE
 DI-N-BUTYLPHTHALATE
 NAPHTHALENE
 2-METHYLNAPHTHALENE
 2,4 DIMETHYLPHENOL
 1-HEXANOL 2-ETHYL
 DIBENZOFURAN
 BIS(2 ETHYLHEXYL)PHTHALATE
 ANILINE
 CHLORONAPHTHALENE
 1,2 DICHLOROBENZENE
 1,3 DICHLOROBENZENE
 1,4 DICHLOROBENZENE
 DBCP
DIAZINON
ALPHA-BHC
4,4 DDT
2,4-D
2,4,5-TP
4,4 ODD
HEPTACHLOR EPOXIDE
ALDRIN
ISODRIN
ENDRIN
DIELDRIN
4,4 DDE
ENDOSULFAN II
ETHYLPARATHION
75-09-2
67-64-1
56-23-5
108-88-3
75-01-4
67-66-3
107-06-2
DIMP
1330-20-7
100-41-4
108-90-7
78-87-5
79-00-5
   7
   7

78-93-3
86-73-7
108-95-2
85-01-8
   7
85-68-7
84-66-2
84-74-2
91-20-13
91-57-6
106-44-5
104-76-7
132-64-9
117-81-7
62-53-3
91-58-7
95-50-1
541-73-1
106-46-7
96-12-18
333-41-5
319-84-6
50-29-3
94-75-7
93-72-1
72-54-8
1024-57-3
309-00-2
    7
72-20-8
60-57-1
72-55-9
33213-65-9
56-38-2
 (A) ABBREVIATION CODE USED ON FIGURES  5-24  THROUGH 5-34  OF THE REMEDIAL
    INVESTIGATION REPORT.

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                                TABIiE 3

                         ROCKY MOUNTAIN ARSENAL
                         EPA OFF-POST RI/FS SITE

          RECENT ANALYTICAL RESULTS FOR SACWSD MUNICIPAL WELLS
                               (UG/LITER)

                                           SAMPLING DATE
CHEMICAL

WELL NO. 1

METHYLENE CHLORIDE

WELL NO. 2

1,1-DICHLOROETHANE
1,1,1-TRICHLOROETHANE
TRICHLOROETHYLENE
TETRACHLOROETHYLENE
METHYLENE CHLORIDE

WELL NO. 3

1,1,1-TRICHLOROETHANE
TRICHLOROETHYLENE
TRANS-1,2-DICHLOROETHYLENE
METHYLENE CHLORIDE
TETRACHLOROETHYLENE

WELL NO. 5

TRICHLOROETHYLENE
TETRACHLOROETHYLENE
BROMOFORM
METHYLENE CHLORIDE
1,1,1-TRICHLOROETHANE

WELL NO. 12

TRICHLOROETHYLENE

WELL NO. 14

TRICHLOROETHYLENE
TETRACHLOROETHYLENE
NOV
85
NS
6
7
19
11
LT1
5
46
; 3
LT1
8
11
4
14
LT1
LT1
NS
8
2
DEC
85
NS
4
5
31
7
9
4
39
LT2
9
5
6
3
LT1
7
LT1
NS
NS
NS
JAN
86
NS
LT1
6
40
5
LT1
6
40
LT2
LT1
4
7
LT1
LT1
LT1
LT1
NS
NS
NS
FEE
86
4
(A) LT1
3
29
4
3
3
40
LT2
LT1
5
7
3
LT1
3
1
3
NS
NS
MAR
86
(B) NS
LT1
3
36
LT1
(B) LT1
4
47
LT2
LT1
5
7
LT1
LT1
(B) LT1
LT1
NS
NS
NS
MAY
86
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS

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                                TABIiE 3

          RECENT ANALYTICAL RESULTS FOR SACWSD MUNICIPAL WELLS
                         (UG/LITER)  (CONTINUED)

                                           SAMPLING DATE
CHEMICAL

WELL NO. 15

METHYLENE CHLORIDE
1,1,1-TRICHLOROETHANE
1,1-DICHLOROETHANE
TRANS 1,3-DICHLOROPROPENE

WELL NO. 16

1,1,1-TRICHLOROETHANE
TRICHLOROETHYLENE
TETRACHLOROETHYLENE
CHLOROFORM
METHYLENE CHLORIDE
1,1-DICHLOROETHANE

WELL NO. 17

1,1,1-TRICHLOROETHANE
TRICHLOROETHYLENE
TETRACHLOROETHYLENE
METHYLENE CHLORIDE
1,1-DICHLOROETHYLENE

WELL NO. 18

1,1,1-TRICHLOROETHANE
TETRACHLOROETHYLENE
1,1,2,2-TETRACHLOROETHANE
METHYLENE CHLORIDE
TRICHLOROETHYLENE
TOLUENE
NOV
85
NS
NS
NS
NS
5
15
8
LT1
LT1
LT1
4
10
1
LT1
LT1
1
1
2
LT1
LT1
LT1
DEC
85
5
LT1
LT1
LT1
NS
NS
NS
NS
NS
NS
3
8
LT1
4
LT1
LT1
LT1
LT1
11
2
2
JAN
86
LT1
LT1
LT1
LT1
4
13
5
2
LT1
LT1
5
8
LT1
LT1
LT1
3
LT1
LT1
LT1
2
LT1
FEE
86
(A) 4 (B)
1
2
2
5
14
5
LT1
4 (B)
4
3
9
LT1
3 (B)
LT1
LT1
LT1
LT1
LT1
LT1
LT1
MAR
86
LT1
2
LT1
LT1
5
11
LT1
LT1
LT1
6
5
9
LT1
LT1
LT1
LT1
LT1
LT1
LT1
LT1
LT1
MAY
86
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
3
12
2
4
2
NS
NS
NS
NS
NS
NS
NS  = NOT SAMPLED
 (A) CONCENTRATIONS ARE  BELOW THE APPROXIMATE METHOD/SAMPLE DETECTION  LIMIT  LISTED
 (B) METHYLENE CHLORIDE  WAS  ALSO FOUND IN THE LABORATORY BLANK AT  4 UG/LITER
SOURCE:  HRS WATER CONSULTANTS,  INC.  SUMMARY DATA AND CENREF LABS LABORATORY REPORTS.

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                               TABIiE  4

                        ROCKY MOUNTAIN ARSENAL
                        EPA OFF-POST  RI/FS  SITE

           TOTAL POTENTIAL EXCESS CANCER RISKS ASSOCIATED WITH
            INGESTION AND INHALATION  EXPOSURE  ROUTES — SACWSD
                           MUNICIPAL  WELLS  (A)

                         ADDITIVE CANCER RISK     ADDITIVE CANCER RISK
ROUTE OF EXPOSURE         FOR 2-YEAR  EXPOSURE      FOR LIFETIME EXPOSURE

                                          MINIMUM EXPOSURE

     INGESTION                 6 X  10-8                    2 X 10-6
     INHALATION                5 X  10-9                    1 X 10-7

          TOTAL RISK           6 X  10-8                    2 X 10-6

                                          MEAN EXPOSURE
     INGESTION                 3 X  10-7                    1 X 10-5
     INHALATION                2 X  10-8                    8 X 10-7

          TOTAL RISK           3 X  10-7                    1 X 10-5

                                         MAXIMUM EXPOSURE
     INGESTION                 2 X  10-6                    1 X 10-4
     INHALATION                1 X  10-6                    3 X 10-5

          TOTAL RISK           3 X  10-6                    1 X 10-4

(A)  TOTAL EXCESS CANCER RISKS WERE  OBTAINED BY SUMMING THE RISKS
    ASSOCIATED WITH INGESTION AND INHALATION EXPOSURE TO
    1,1-DICHLOROETHYLENE, TRICHLOROETHYLENE, AND TETRACHLOROETHYLENE,
    RESPECTIVELY. TRICHLOROETHYLENE AND  TETRACHLOROETHYLENE ARE
    CLASSIFIED IN EPA'S WEIGHT-OF-EVIDENCE  FOR CARCINOGENICITY
    GROUP B2, MEANING THEY ARE CONSIDERED PROBABLE HUMAN
    CARCINOGENS. 1,1-DICHLOROETHYLENE IS CLASSIFIED IN GROUP C, MEANING
    IT IS CONSIDERED A POSSIBLE HUMAN CARCINOGEN.  EXPOSURE TO
    1,1-DICHLOROETHYLENE IS ONLY CONSIDERED UNDER THE MAXIMUM EXPOSURE
    CONCENTRATION SCENARIO.

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                                TABIiE  7
                    CAPITAL COSTS - CARBON ADSORPTION

ITEM                                                              COST

 1.  LAND                                                     $  250,000
 2.  TRANSMISSION SYSTEM
    A)   REPLACEMENT WELL PUMPS, MOTORS,  CONTROLS
            WELL NO.      H.P.
               2            50                                   31,900
               3           100                                   47,300
               5           150                                   61,300
              14            50                                   31,900
              15            25                                   23,500
              16            40                                   28,000
              17           150                                   61,300
    B)   DISTRIBUTION SYSTEM                                     830,700
                              SUB-TOTAL  TRANSMISSION SYSTEM $1,115,900
 3.  BUILDING  (A)
        15,700 S.F.; 30 FT. HIGH                             $1,020,500
 4.  OFFICE BUILDING AND LAB  (B)
        3,550 S.F                                               284,000
 5.  GC EQUIPMENT                                                 50,000
 6.  CHLORINATION AND CHEMICAL FEED EQUIPMENT                    105,000
 7.  SITEWORK/LANDSCAPING                                        166,200
 8.  CARBON ADSORBERS, PIPING, INSTRUMENTATION,  CLEARWELL     3,300,000
 9.  CARBON - INITIAL CHARGE  (400,000 LB)                        400,000
                           SUB-TOTAL                         $6,691,600

                                 CONTINGENCY  (15%)            1,003,700
                                 ENGINEERING,  DESIGN (C)        839,100
                                 CONSTRUCTION  ENGINEER (5%)     334,600

                                          SUB-TOTAL  (E)      $8,869,000

10.  TEMPORARY GAG SYSTEM LEASE AND CARBON CHANGEOUT  COSTS
        (NEEDED TO FUND AS OF 12/86)  (D)                        908,900

                                          TOTAL (E)          $9,777,900

(A)  BASED ON $65/S.F. PRICE IS BASED UPON A STEEL  FRAME  BUILDING.  THE
    EXTERIOR WALLS ARE CONCRETE BLOCK. ESTIMATED ADDED SQUARE FOOT COSTS
    FOR OTHER EXTERIOR FINISHES ARE:

        PRECAST CONCRETE PANELS    $3/SF
        INSULATED METAL PANELS     $0/SF
        FACE BRICK ON COMMON BRICK $7.50/SF

FOOTNOTES CONTINUED ON PAGE 35

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                                 TABIiE 7
               CAPITAL COSTS - CARBON ADSORPTION  (CONTINUED)

(B)  BASED ON $80/SF

(C)  SACWSD

(D)  BASED ON:

    LEASE COSTS FROM 1/1/87:  $23,846/MO X 21 MO =  $500,800
    MONTHLY MONITORING AND O&M:  $5000/MO X 21 MO    105,000
    GAG  CHANGEOUT                                    294,400
    DEMOBILIZATION OF TREATMENT PLANT                131,100
    DEMOBILIZATION OF TEMPORARY STRUCTURE             34,400
    CONTINGENCY $2000/MO X 21 MO                      42,000

                                                  $1,107,700
    FUNDS AVAILABLE 12/86                            198,800

                                                    $908,900

(E)  ADDITIONAL ESTIMATED COSTS FOR AN AIR STRIPPING FACILITY TO  TREAT
    VINYL CHLORIDE,  IF NEEDED, ARE $1,231,000. THIS FIGURE  IS  BASED  ON
    ESTIMATED CAPITAL COST OF $962,000 PLUS CONTINGENCY  (15%),
    ENGINEERING (8%),  AND CONSTRUCTION ENGINEERING  (5%). DETAILS ARE
    GIVEN IN ATTACHMENT C OF THE RESPONSIVENESS SUMMARY. TOTAL
    CAPITAL COSTS INCLUDING THE AIR STRIPPING FACILITY WOULD BE
    $10,100,000.  TOTAL COSTS, INCLUDING CONTINUATION OF  LEASING,
    OPERATION,  AND DEMOBILIZATION OF THE TEMPORARY GAG SYSTEM  WOULD  BE
    $11,008,900.

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                                 TABIiE  8

   ANNUAL O&M COSTS AND EQUIPMENT REPLACEMENT COSTS - CARBON ADSORPTION

ITEM                                                           COST

 1. LABOR
         1 OPERATOR  (CLASS A)     2920  X  $20                 $ 58,400
         1 LABORER                2080  X  $15                   31,200
         MECHANICAL & ELECTRICAL    200  X  $20                    4,000

 2. POWER
         WELLS                                                 44,000
         BUILDING HVAC AND LIGHTING                           24,000
         CHEMICAL FEED PUMPS  (1 KW)(24  HRS/DAY)
           (30 DAY/MO)(12 MO)($0.06/KW)                           500

 3. CARBON REPLACEMENT
         (400,000 LB/YEAR)  ($1.00/LB)                         400,000

 4. GAG CONTACTOR MAINTENANCE
         $1,500/UNIT/CHANGEOUT FOR  INSP & MAINT                25,000

 5. CHLORINE  (BY DISTRICT)                                       -0-

 6. SODIUM HEXAMETAPHOSPHATE
       DOSE 0.5 MG/L =40 GAL/WEEK
         1 DRUM/WEEK X $326/DRUM X  52                          17,000
                                  ANNUAL  O&M                $ 604,100

 7. EQUIPMENT REPLACEMENT COSTS  (OVER 30  YEARS)
    A. WELL PUMPS EVERY 10 YEARS  (BY DISTRICT)                   -0-
    B. CHEMICAL FEED EVERY 10 YEARS (2)  (50,000)              100,000
    C. LINING REPLACEMENT EVERY 5 YEARS (5)  (68,000)          340,000
                                  TOTAL                    $ 440,000.

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