United States
Environmental Protection
Agency
Off ice of
Emergency and
Remedial Response
EPA/ROD/R08-90/041
May 1990
&EPA
Superfund
Record of Decision
Rocky Mountain Arsenal
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50272-101
REPORT DOCUMENTATION 11. REPORTNO.
PAGE EPA/ROD/R08-90/041
2.
:s. R8c1pIent'8 ACC888Ion No.
4. TIII8 Md Subtile
SUPERFUND RECORD OF DECISION
Rocky Mountain Arsenal (Operable
Sixth Remedial Action
7. Aulhor(8)
5. Report Data
05/03/90
Unit 22), CO
8.
8. PIIrfonnlng Organization Rapt. No.
I. PIIrfonnlng Org8lnlzatlon Nama and AcId.....
10. Proj8ctlT88IIIWoril UnIt No.
11. ~ct(C) III Gr8nt(0) No.
(C)
(0)
12. 8ponaortng Organlz8llon Nama Md Addr888
U.S. Environmental Protection
401 M Street, S.W.
Washington, D.C. 20460
13. Type of Report. P8r1od Co-.l
Agency
800/000
14.
15. Supp/8m8nt8ry No..
18. Ab8tr8ct (UmIt: 200 _Ida)
The 17,000-acre Rocky Mountain Arsenal (RMA) (Operable Unit 22) site is a former U.S.
Army chemical warfare and incendiary munitions manufacturing and assembly plant in Adams
County, Colorado. From the 1950s to late 1969, the U.S. Army used the RMA facility to
produce the nerve agent GB (isopropylmethylphosphonofluoridate). In addition, from 1947
to 1982, private industries leased major portions of the plant facilities to manufacture
~arious insecticides and herbicides. Since 1970, U.S. Army facility operations have
~rimarily involved the destruction of chemical warfare materials. Because final
remediation of the RMA site will take many years to complete, thirteen interim response
actions (IRAs) were determined necessary prior to implementing the final On-Post Record
of Decision (ROD). Operable Unit 22 (OU22), the Complex Disposal Trenches, is one of
several areas being addressed as part of the Other Contaminated Sources Interim Remedial
Action. These disposal trenches are located in the 107-acre Site 36-17N in the center
of the RMA. During the 1940s and 1950s, this area was the primary disposal area for
solid chemical waste, contaminated tools and equipment, rejected incendiaries, and empty
munitions casings. This waste was decontaminated, placed in onsite pits, and burned
(See Attached Page)
17. Docum8nt An8/y8I8 L D88crtpt01'8
Record of Decision - Rocky
Sixth Remedial Action
Contaminated Media: None
Key Contaminants: None
Mountain Arsenal (Operable Unit 22), CO
b. IIMn~End8cI T-
Co COSA 11 Fl8ldfQroup
1A. AVIiI8bIIty SIat8m8nI
11. S8c:I81ty CI- (11118 R8port)
None
20. S8c:I81ty a- (ThI8 P8ga)
Nnnp
21. No. of Pagaa
90
22. Price
(Sea ANSI-Z38.18)
See IMIrUctI- on ~-
(Fonnatty NTIS-35)
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EPA/ROD/R08-90/041
ocky Mountain Arsenal (Operable Unit 22), CO
ixth Remedial Action
Abstract (Continued)
using fuel oil to ensure complete decontamination. Salvageable materials such as metal
were sold as scrap after burning, and nonsalvageable materials were buried in onsite
pits. Investigations by RMA in 1988 and 1989 identified onsite contaminated soil and a
variety of buried waste, including scrap metal, concrete rubble, wood, charcoal, drums of
waste chemicals, and glass vials containing unknown liquids. Ground water under the site
also was determined to be contaminated. The main source area for the contaminant plume,
however, appears to be from upgradient trenches located south of Site 36-17N. Ground
water contaminant sources are the subject of another ROD. The selected interim remedial
action is designed to prevent taking measures that may be incompatible with final
decisions. Therefore, this ROD will not address the primary contaminants of concern
affecting the soil and ground water. Remediation of contaminated media will be a
component of the final site remedy.
The selected interim remedial action for this site is no further action with the
installation of further ground water wells for further site characterization; and ground
water monitoring. A reevaluation procedure will identify the need for any additional
onsite remedial actions. No costs were provided for this interim remedial action.
PERFORMANCE STANDARDS OR GOALS:
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MATERIEL COMMAND
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FINAL DECISION DOCUMENT
FOR THE INTERIM RESPONSE AcnON
AT THE ".; I.' 1'-;" /'
COMPLEX DISPOSAL TRENCHES
ROCKY MOUNTAIN ARSENAL
AP~ 1990
CONTRACf NO. DAAA15-88-D-0022/CXYJ2
VERSION 4.0
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Prepared by:
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WOODWARD-CLYDE CONSULTANTS
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Prepared for:
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PROGRAM MANAGER FOR ROCKY MOUNTAIN ARSENAL
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THE INFORMATION AND CONa.USIONS PRESENTED IN nus REPORT REPRESENT THE
OFFICIAL POSmON OF THE DEPARTMENT OF THE ARMY UNLESS EXPRESSLY MODIFIED BY
A SUBSEQUENT DOCUMENT. nus REPORT CONSTITUTES THE RELEVANT PORTION OF THE
ADMINISTRATIVE RECORD FOR nus CERCIA OPERABLE UNIT.
THE USE OF TRADE NAMES IN nus REPORT DOES NOT CONSTITUTE AN OFFICIAL
ENDORSEMENT OR APPROVAL OF THE USE OF SUCH COMMERCIAL PRODUCI'S. THE REPORT
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Woodward-Clyde Consultants
TABLE OF CONTENTS"
Section
~
1.0 INTRODUCI10N
1-1
2.0 HISTORY OF THE COMPLEX DISPOSAL TRENCHES
2-1
3.0 INTERIM RESPONSE ACI10N OBJECTIVE
3-1
4.0 INTERIM RESPONSE ACI10N ALTERNATIVES AND EVALUATION
4-1
4.1 INTERIM RESPONSE ACl10N ALTERNATIVES
4-1
4.1.1 Monitoring
4.1.2 Containment
4.1.3 Source Removal and Temporary Storage
4-1
4-1
4-2
4.2 IRA ALTERNATIVES EVALUATION
4-2
.L..
4.2.1 Overall Protectiveness of Human Health and the Environment
4.2.2 Benefit in Terms of Accelerated Cleanup
4.2.3 Benefit in Terms of Cost
4-3
4-4
4-6
4.3 CONCLUSIONS
4-7
5.0 amONOLOGY OF EVENTS
5-1
6.0 SUMMARY OF THE INTERIM RESPONSE ACI10N
6-1
6.1 MONITORING PROGRAM
6.2 REEVALUATION PROCEDURE
6.3 HEALTH & SAFETY PlAN
6-1
6-1
6-4
7.0 INTERIM RESPONSE ACI10N PROCESS
7-1
. -
8.0 APPUCABLE OR RELEVANT AND APPROPRIATE
REQUIREMENTS FOR THE REMEDIATION OF OTIIER CONTAMINATION
SOURCES - SECI10N 36 TRENCHES INTERIM RESPONSE ACI10N
8-1
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8.1 INTRODUcnON
8-1
(11111C02-4200) (DECDOC.CVR) (03{14/90)
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8.2 AMBIENT OR CHEMICAL-SPECIFIC ARARS
8-1
8.2.1 Air Emissions
8-1
8.3 LOCATION-SPECIFIC ARARS
8-2
8.4 AcrION-SPECIFIC ARARS
8-3
8.4.1 Description
8.4.2 Construction Occurring Incident to the IRA
8-3
8-3
8.5 COMPLIANCE WITH THE OTHER ENVIRONMENTAL LAWS
8-10
9.0 SCHEDULE
9-1
10.0 roNSISTENCY WITH THE FINAL REMEDIAL AcrION
10-1
11..0 REFERENCES
11-1
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APPENDIX A - roMMENTS AND RESPONSES
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APPENDIX B - SOn. AND GROUNDWATER roNTAMlNATION DATA
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(11111 c:m.4200) (DECDOC.CVR) (03/24/90)
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F1GURES
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1-1 Decision F10w Chart for Other Contamination Sources IRAs
1-2
2-1 Location Map Rocky Mountain Arsenal
2-2
2-2 Location of Trenches in Site 36-17N
2-4
2-3 Monitoring Well LocatioDS
2-6
6-1 Reevaluation Process for Army Complex Disposal Trenches IRA
6-3
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(11111C02-4200) (DECDOC.CVR) (03(JA/90)
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Woodward. Clyde Consultants
LO
INTRODUcnON
The Interim Response Action (IRA) alternatives assessment and decision process for the Complex
Disposal Trenches at the Rocky Mountain Arsenal (RMA) are being conducted as part of the IRA
process for RMA in accordance with the Federal Facility Agreement and the Technical Program Plan.
Determinations concerning the implementation of this IRA have been reached through a consideration
of the objectives of Sections 2.3(a), 22.5, and 22.6 of the Federal Facility Agreement, and by application
of the Decision Flow Chart for Other Contamination Sources IRAs adopted by the Organizations and
the State of Colorado at the June 7, 1989 Subcommittee meeting (rtgure 1-1).
J-
Alternatives have been reviewed based on their overall protectiveness of human health and the
environment; benefit in terms of accelerated cleanup, including technical benefit of performing an IRA
now, timeliness of implementation, and consistency with the fmal remedy; and benefit in terms of cost.
Due to the type of response actions being considered for this IRA, it is assumed for evaluation purposes
that any of the alternatives under evaluation would be designed to meet Applicable or Relevant and
Appropriate Requirements (ARARs) to the maximum extent practicable. The preferred IRA consists
of monitoring the Complex Disposal Trenches for migration of contaminants.
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(11111CX12-4200) (TRENQUJRA) (03/24/90) (RMA)
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SITE CHARACTERIZATION
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.DOES SITE
POSE A
SIGNIFICANT RISK
TO HUMAN OR
BIOTA RECEPTORS
?
INTERIM RESPONSE
ACTION SELECTION
NO
OR DATA
INADeQUATE
NO
Job No. : 22238-4200
Preoored by: K. A. S.
Dote: 12/18/89
Woodward.CIyde Consuftants
MONITORINGI MAINTENANCE
NO
YES
DECISION FLOW CHART FOR OTHER
CONTAMINATION SOURCES IRAs
Figure 1-1
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2.0
msroRY OF THE COMPLEX DISPOSAL TRENaIES
Roclcy Mountain Arsenal (RMA) occupies more than 17,000 acres (approximately 27 square miles) in
Adams County, directly Dortheast of metropolitan DeDver, Colorado (see rIgW'e 2-1). The property was
purchased by the U.s. GovemmeDt in 1942 for use in W orId Warn to manufacture and assemble
chemical warfare materials, such as mustard and lewisite, and inceDdiary munitioDS. Starting in the
195Os, RMA produced the Derve ageDt GB (isopropyl methylphosphoDofluoridate) until late 1969. A
significant amount of chemical warfare materials destructioD took place during the 19505 and 1960s.
Since 1970, RMA has primarily heeD involved with the destructiOD of chemical warfare materials. The
last military operatioDS at RMA eDded in the early 198Os. In November 1988, the RMA was reduced
to inactive military status reflecting the fact that the only remaining missioD at the ArseDal is
coDtaminatioD cleanup. In addition to these military activities, major portioDS of the plant facilities were
leased to private industries, including Shell Oil Company, for the manufacture of various insecticides and
. herbicides between 1947 and 1982.
II';
The Phase I and Phase n CoDtammation Assessment Reports (CARs) (ESE 1988a and 1988b) as well
as the Central Study Area Report (CSAR) (Ebasco 1989a) and the North Central Study Area Report
(NCSAR) (Ebasco 1989b) desaibe the nature and extent of contamination throughout Section 36.
These reports describe the soil and groundwater throughout SectioD 36 as being contaminated with a
wide range of organics, ICP metals (cadmium, chromium, copper, lead, and zinc), arsenic, and mercury.
. ..
Basin A, located immediately west of the Complex Disposal Trenches, was the primary liquid waste
disposal site at RMA in the 1940s and 1950s. Although Basin A no longer contains standing liquids, the
remaining sludge and soil beDeath Basin A is contaminated with volatile organic compounds,
organosulfur compounds, organophosphorus compounds, organochlorine pesticides, arsenic, and mercury
(Ebasco 1989b).
! ..
The Complex Disposal Trenches are located in the east-central portion of Section 36, in Site 36-17. Site
36-17 is a 107-acre site that is divided into a northern (Site 36-17N) and a southern (Site 36-175)
portion. Site 36-17N is further subdivided into eight anomalous areas located during a geophysical
investigatioD conducted during the Phase I fieldwork (ESE 1988a). These areas are identified as
Anomalous Areas A through H. The Complex Disposal Trenches in Anomalous Areas A and H are
evaluated as being in close, or direct, CODtact with groundwater during parts of the year. TreDches in
Anomalous Areas B and C are known to CODtain hazardous materials from previous investigatioDS.
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2-1
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Trenches in Anomalous Areas A, B, C, and H are considered for a possible interim response action in
the IRA Alternatives Assessment(WCC 1989a). FIgUre 2-2 identifies the Anomalous Areas and the
trench areas considered for this IRA. .
Site 36-17S also contains some disposal trenches that are being investigated for an IRA by Shell Oil
Company. This IRA Decision Document focuses only on the Army Complex Disposal Trenches in Site
36-17N.
.."
Site 36-17N was the primary solid waste disposal area at RMA in the 1940s and 1950s. Solid chemical
waste and potentially contaminated tools, equipment, unwanted containers, rejected incendiaries, and
empty munitions casings were decontaminated with caustic or another decontaminant and then hauled
to burning pits and burned to ensure complete decontamination. The burning pits/trenches,
approximately 8 to 10 feet deep, 15 .feet wide, and up to 100 to 200 feet long, typically had a bottom
layer of approximately 4 to 5 tons of lumber. The solid waste was placed on top of the lumber until the
pit was full. Additional lumber and approximately 300 to 500 gallons of fuel oil were then placed into
the pit, and the contents were burned. Remaining metal was checked for contamination and reburned,
if necessary. The decontaminated, salvageable metal remained in the pit; some of it was later removed
and sold as scrap. The pit was then backfilled which buried the nonsaIvageable materials. Burning and
disposal pits appear to have been dug in the area on a regular basis until the late 1960s (ESE 1988a).
,-.;
Phase I and Phase II field investigations found that the Complex Disposal Trenches contain a wide
variety of wastes, as well as potentially hazardous materials. The waste types include contaminated soil,
scrap metal, concrete rubble, wood and charcoal, drums of waste chemicals, and glass vials containing
unknown liquids. The hazardous materials, which are potentially present, include unexploded ordnance,
Army agents or agent degradation products, and unburned incendiaries (ESE 1988a and 1988b). An
additional field investigation conducted in spring and summer 1989 confirmed these [mdings (WCC
1989b). Contaminants found in the Complex Disposal Trenches soils include the ICP metals (cadmium,
chromium, copper, lead, and zinc), arsenic, mercury, organochlorine pesticides, diisopropylmethyl
phosphonate (DIMP), and organosulfur compounds.
The alluvial groundwater in the Complex Disposal Trench area flows to the north and northwest under
unconfmed conditions, then northwest out of the Basin A neck. Anomalous Areas A and H are located
on the eastern fringe of this portion of the north-northwest flowing alluvial aquifer. The top of the
bedrock surface protrudes above the groundwater table along the prominent northwest to southeast
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2-3
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Woodward.Clyde Consultants
BASIN A AREA
/ 2.3 24 19 20
/I 27 26 25 .30 29
33 34 35 ~ 31 32
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KEY MAP
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LEGEND
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o Anomalous area (A-H)
. Well location
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Job No.: 22238-4200
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LOCATION OF TRENCHES IN SITE 36-17N
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Woodward-Clyde Consultants
trending bedrock ridge in Section 36. The alluvium that caps, the bedrock ridge is unsaturated.
Anomalous Areas B and C are located over this unsaturated alluvium.
Groundwater contamination in the vicinity of the Complex Disposal Trench area is summarized in
Appendix B. . Figure 2-3 shows the locations of the groundwater monitoring wells used for the summary
in Appendix B. The Central Study Area Report (Ebasco 1989a) and the RMA data base provide details
of the groundwater contamination in the vicinity of the Complex Disposal Trenches.
t-
Groundwater in the saturated alluvium underlying Anomalous Areas A and H is highly contaminated
with organic contaminants. The plume for these contaminal'Jts originates in Site 36-17S and moves up
through Site 36-17N underlying Anomalous Areas A and H. Contaminant concentrations do not
generally increase as the contaminant plume in the alluvial aquifer moves from Site 36-17S through Site
36-17N. The contaminants include volatile organic compounds; DBCP; organophosphorous compounds
(DIMP, dimethylmethyl phosphonate [DMMP), and methylphosphonic acid [MPA)); and organosulfur
compounds, both mustard related (dithiane and oxathiane) and herbicide related (chlorophenylmethyl
sulfide [CPMS), chIorophenylmethyl sulfoxide [CPMSO), and chIorophenylmethyl sulfone [CPMS02)).
Low concentrations of organochlorine pesticides, and relatively low concentrations of arsenic arc also
present in the plume moving from Site 36-17S through Site 36-17N. Some ICP metals are present only
in a few wells at relatively low concentrations. Groundwater flow rates were calculated using the lower
and upper limits of estimated hydraulic gradients and hydraulic conductivities for Section 36. On the
basis of these parameters, the calculated flow rate in the alluvial aquifer ranges from approximately 7
to 186 feet/year.
1 ~
. ..
Wells completed in the bedrock, northeast of Anomalous Areas B and C, show some concentrations of
volatile halogenated organics, volatile aromatic organics, and DIMP. These contaminants were not
found in soil samples in Anomalous Areas B and C. However, due to the heterogeneous nature of the
trench contents, there is some possibility that the groundwater contamination is coming from these
trenches. Another explanation for this contamination may be that groundwater from the contaminated
alluvial aquifer is infUtrating the bedrock. Although the majority or alluvial groundwater entering Site
36-17N from the south encounters the bedrock ridge and is subsequently diverted to the northwest, the
bedrock is not absolutely impermeable. Some alluvial groundwater may penetrate either the bedrock
itself, or any fracture in the bedrock that may be present, and move down the hydraulic gradient in the
Denver Formation to the northeast. Therefore, some contamination present in the alluvial aquifer could
possibly be transported through the bedrock. Movement or this contamination would be much slower
than in the saturated alluvium because of the lower hydraulic conductivity of the bedrock. The
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(11111CD2-4200) (TRENCH2.IRA) «(J3(JAf90) (RMA)
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calculated flow rate to the northeast of the Complex Disposal Trench area, where flow occurs primarily
in the Denver Formation, ranges from approximately 0.2 to 1.6 feet/year. However, there are no
monitoring wells upgradient of Anomalous Areas B and C which can be used to evaluate contaminant
migration from the alluvial aquifer into the bedrock. Therefore, data do not exist to evaluate whether
groundwater contamination in the bedrock is due to the Anomalous Area B and C trenches or
infiltration from the alluvial aquifer.
In summary, soil samples taken in the Complex Disposal Trench area show metals to be the primary
contaminants, with some indications of organics. It appears that the alluvial aquifer is contaminated
primarily with a wide range of organic compounds. Although the Army Complex Disposal Trenches
appear to be contributing to the degradation of groundwater quality, wells upgradient of the trenches
area indicate that the alluvial aquifer is heavily contaminated prior to entering the Complex Disposal
Trench area. The metals that are the primary contaminants in the soil samples from the trenches have
been detected in the alluvial groundwater. However, groundwater sampling and analysis show no clear
trend of metal contaminant distribution downgradient of the trenches area.
1..';
On February 1, 1988, a proposed Consent Decree was lodged in the case of U.S. v. Shell Oil Company
with the U.S. District Court in Denver, Colorado. The proposed Consent Decree was revised after
public comments were received, and a modified proposed Consent Decree was lodged with the Court
on June 7, 1988. In February 1989, a Federal Facility Agreement was entered into between Shell Oil
Company and five federal agencies: the u.s. Environmental Protection Agency, the Army, the
Department of the Interior, the Department of Health and Human Services, and the Department of
Justice, which established procedures for implementing the Arsenal cleanup program as specified in the
Technical Program Plan and incorporates many provisions of the modified proposed Consent Decree.
The Army and Shell Oil Company agreed to share certain costs of the remediation to be developed and
performed under the oversight of the U.S. Environmental Protection Agency, with opportunities for
participation by the State of Colorado. The long-term remediation is a complex task that will take
several years to complete. The Federal Facility Agreement specifies 13 IRAs determined to be
. necessary and appropriate. The Remediation of Other Contamination Sources is one of the 13 1RAs.
The Complex Disposal Trenches are one of several sites being addressed by the remediation of other
contamination sources IRA.
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(111l1CX!2-4200) (TRENCH2.IRA) (03/24/90) (RMA)
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3.0
INTERIM RESPONSE AcnON OBJECI1VE
The objective of the Interim Response Action (IRA) Alternatives Assessment for the Complex Disposal Trenches
is to assess whether immediate action at this site is appropriate and to recommend, if necessary, an interim
response action alternative to mitigate the threat of release of contaminants from the Complex Disposal Trenches
on an interim basis, pending determination of the final remedy in the Onpost Record of Decision (ROD).
The IRA alternatives have been evaluated with respect to the aiteria specified in the Federal Facility Agreement,
paragraphs 22.5 to 22.7. . The evaluation of these aiteria is applied within the context of the Decision Flow Chart
for Other Contamination Sources mAs (FIgW'e 1-1). These aiteria are:
~
. Overall protection of human health and the environment
. Benefit in Terms of Ac:cclerated Cleanup
Technical Benefit of Performing an IRA Now
Timeliness of implementation
Consistency with the final remedy
. Benefit in Terms of Cost
j/,.J
This Decision Document provides a summary of the alternative technologies considered, a chronology of the
significant events leading to the initiation of the IRA, a summary of the IRA project, and a summary of the
ARARs (legal and regulatory standards, aiteria, or limitations) associated with the program. Due to the type
of response actions being considered in this IRA Alternatives Ass~c.~ment, it is assumed for evaluation purposes
that any of the alternatives under evaluation would be designed to meet ARARs to the maximum extent
practicable.
As specified in the Federal Facility Agreement, this IRA wilJ, by monitoring and adding to the site
charaderization, to the maximum extent practicable, be consistent with and contn'bute to the efficient
performance of the rmal Response Action.
(111l1CD2-4200) (TRENCH3.JRA) (aJ!Z4/90) (RMA)
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Woodward. Clyde Consultants
4.0
INTERIM RESPONSE ACI'ION ALTERNATIVES AND EVALUATION
This section describes the interim response action (IRA) alternatives developed in the IRA Alternatives
Assessment for the Complex Disposal Trenches and discusses the evaluation of these alternatives.
4.1 INTERIM RESPONSE ACI'ION ALTERNATIVES
Appropriate interim response action alternatives for the Complex Disposal Trenches were evaluated in the
.Alternatives Assessment of Interim Response Actions for Other Contamination Sources - Complex
Disposal Trenches. (Wee 1989). These alternatives include:
. Monitoring
. Containment
. Source Removal and Temporary Storage
..-
Following is a brief description of these alternatives.
1..1
4.1.1 Monitorini
This alternative would consist of conducting groundwater sampling in the vicinity of the Complex Disposal
Trenches. Additional monitoring wells would be constructed to better evaluate the effed of the trenches
on groundwater contamination. Monitoring would allow continued tracking of the effect of the Complex
Disposal Trenches on overall groundwater quality in Section 36.
4.1.2 Containment
This alternative would consist of two aspects of containment The first would be subsurface barriers to
prevent lateral migration of contaminAnts with the groundwater. The subsurface barriers would be either
slurry walls or sheet pilings, that would be constructed so that they are keyed into the low permeability
strata beneath the disposal trenches. Since the trenches in Anomalous Areas A and H have the potential
for lateral contaminant migration due to their proximity to groundwater, they would be the trenches
requiring these barriers.
(11111CD2-4200) (TRENCH4JRA) (03/24/90) (RMA)
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Woodward-Clyde Consultants
The other aspect of containment" would be the use of either multilayered caps or groundwater extraction
and treatment. A multilayered cap can minimize inflltration of precipitation and surface water through the
trench contents. Groundwater extraction and treatment would maintain a reverse hydraulic gradient across
the subsurface barrier, thereby reducing contaminant migration. Trenches in Anomalous Areas A. B, C,
and H would be partially contained by one, or a combination of these technologies.
4.1.3 Source Removal and Temporarv StoralZe
.....
This alternative would consist of excavating the contents of the trenches considered for this IRA and storing
those contents in a temporary waste pile on site. This alternative woUld remove the trench contents and
isolate them from the environment. This alternative would require the construction of the temporary waste
pile, containment pads for the sorting operation. and temporary structures with exhaust air scrubbers to
control air emissions during excavation. A water treatment facility may be required since some of the
trench contents may require dewatering and subsequent water treatment. Fmally, the excavation operation
would require specially trained personnel because of the possible presence of Army agents or unexploded
ordnance.
4.2 IRA ALTERNATIVES EVALUATION
w
The previous section described alternatives for addressing the waste materials in the Complex Disposal
Trenches as an interim response action (IRA). The three IRA alternatives considered technically feasible
for this site are monitoring, containment, and source removal with temporary storage.
The IRA Alternatives Assessment (WCC 1989a) evaluates the feasible alternatives for this site with respect
to the criteria specified in the Federal Facility Agreement, paragraphs 22.S to 22.7. The evaluation of these
criteria is applied within the context of the Decision F10w Chart for the Other Contamination Sources IRAs
(F1gUJ'e 1-1). These criteria, interpreted within the context of the Decision F10w Chart, are:
...
. Overall protectiveness of human health and the environment
. Benefit in terms of accelerated cleanup
Technical benefit of performing an IRA now
Timeliness of implementation
Consistency with the final remedy
. Benefit in terms of cost
.....
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Any alternative chosen for this IRA will, to the maximum extent practicable, attain applicable or relevant
and appropriate requirements (ARARs), as required by paragraph 22.7 of the Federal Facility Agreemen~.
As discussed in the IRA Alternatives Assessment, there does not appear to be a significant risk to human
or biota receptors posed by the current situation at this site. Consequently, based on the decision logic in
FtgW'e 1-1, the question of whether there is a long-term benefit in terms of accelerated cleanup or cost
determines the recommended action for this site.
4.2.1 Overall Protectiveness of Human Health and the Environment
&~
The site does not a~pear to be posing a significant risk to human health and the environment (i.e., biota)
at this time. There are no municipal or private wells currently drawing from the portion of the aquifer
affected by the trenches. The North and Northwest Boundary Systems have been installed to intercept and
treat contaminated groundwater that may be emanating from this area, prior to the groundwater flowing
offpost where human receptors may be impacted. Prior to reaching the boundary systems, groundwater may
also be intercepted by the Basin F or Basin A Neck groundwater eXtraction and treatment systems. In
addition, no biota appear to be significantly exposed to the contaminated groundwater beneath Section 36.
Since there is little plant life growing in this area, plant uptake will be minimal.
L..
Monitoring would allow continued tracking of contaminant movement, thereby providing additional
information on protection of human health and the environment. Monitoring would also provide a warning
if conditions change at the site, and risk to human health and the environment increases. If additional
groundwater quality degradation can be seen to be the result of the trench contamination, a reevaluation
of the site would be initiated, as desaibed in Section 6.0. There would be minor short-term impacts on
workers, if additional wells need to be installed, and no short-term impacts On the community during that
operation.
".-
Although the site does not appear to be posing a significant risk to human health and the environment at
this time, both the containment and source removal alternatives can be designed to be protective of human
health and the environment. Both alternatives reduce the mobility of contamination by removing it from
contad with the alluvial groundwater, and by minimi7ing percolation of surface water and precipitation
through the waste material. Both alternatives may increase the volume of material that may ultimately need
to be addressed because possible cap construction materials from the containment alternative and waste pile
construction materials from the source removal alternative may require remediation as part of the Fmal
Onpost Record of Decision (ROD). Some containment alternatives as well as the source removal
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alternative do not mitigate the toxicity of the materials. Although the groundwater extraction and treatment
containment alternative could have some mitigating effect on toxicity through groundwater treatment, this
effect would be inconsequential relative to the amount of contaminated soil and groundwater throughout
Section 36.
There are potential short-term impacts associated with implementing both the containment and source
removal alternatives. Both alternatives involve intrusive activity. Intrusive activity in Section 36 introduces
the potential for releasing air emissions and for contacting randomly buried objects, including possible
unexploded ordnance. However, steps can be taken to minimi7.e the impacts associated with intrusive
activities, such as conducting geophysical surveys, having specially trained personnel perform the intrusive
activities, and implementing engineering controls for air emissions.
4.2.2 Benefit in Terms of Accelerated Cleanup
...
This subsection discusses the technical benefit of performing an IRA now, the timeliness of the various
alternatives considered, and the possible consistency of these alternatives with the final remedy.
4.2.2.1 Technical Benefit of Performing an IRA Now
Li
The approach of this analysis is to consider the technical benefits of containment or source removal and
temporary storage. If no benefit in their implementation can be shown, then the monitoring alternative
would be the most appropriate IRA, in terms of technical benefit. This approach is consistent with the
Decision F10w Chart shown in rlgUre 1-1.
.. .
The technical benefit in performing any containment or source removal action on the Army Complex
Disposal Trenches is limited for several reasons. rll'St, the amount of groundwater contamination
contn"buted by the trenches in Anomalous Areas A and H is small compared to the contamination entering
the site uom upgradient sources. The past disposal practice of burning the waste material prior to burial
appears to have been effective at limiting the residual orgaDic: contamination (WCC 1989a).
. -
Reducing or removing the cont!lmin!lnt contribution uom these trenches would have little effect on overall
groundwater quality in the area. Although a containment alternative such as groundwater cmaction and
treatment would remove some of the conbmin!lnt$ uom the aquifer, this type of operation would be more
efficiently and effectively performed in the context of a comprehensive remedial effort during the final
remedy. The amount of contaminants that could be removed in the time between implementation of an
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IRA and the implementation of some final response action would be inconsequential in the context of the
overall Section 36 groundwater remediation.
Also, the contribution of contaminants by these trenches to the alluvial groundwater would have little impact
on the selection and design of a treatment system installed for the final cleanup of Section 36 groundwater.
In other words, there do not appear to be contaminants specific to the Complex Disposal Trenches that
would influence the treatment system selection process for the final cleanup of Section 36 groundwater.
In addition, information on the effects on groundwater from the trenches in Anomalous Areas B and C is
not conclusive. There are existing wells to the northeast of these Anomalous Areas that have shown some
organic contaminants. It has not been determined whether the source of these compounds is these trenches
or whether these contaminants have migrated into the saturated bedrock from the alluvial aquifer. No
monitoring wells screened in the saturated bedrock currently exist upgradient of Anomalous Areas B and
C. These sites, therefore, require further groundwater characterization (both hydrogeologic and chemical)
before their contribution to groundwater quality degradation can be evaluated.
.-.
F'mally, soil throughout Section 36 is contaminated. Therefore, containment or removal of a minor fraction
of the material that may ultimately require remediation is of limited benefit.
lJ
4.2.2.2 Timeliness of 1m DIem entation
Monitoring could be implemented in a timely manner. Groundwater monitoring wells may be able to be
sampled in conjunction with the Comprehensive Monitoring Program (CMP). Numerous groundwater
monitoring wells have been installed at RMA. II additional wells are determined to be necessary during
the design phase of this IRA, procedures and requirements for well installation are flrmly established.
- .
Containment could be implemented in a fairly timely manner. The intrusive activities required for installing
slurry walls, sheet pilings, or extraction wells would require geophysical surveys because of the possibility
of encountering buried objects. Engineering controls may also be necessary to control possible air
emissions.
.r..
Source removal and temporary storage cannot be implemented in a timely manner. As discussed in
subsection 4.13, this alternative would require construction of a temporary waste pile and sorting areas.
Temporary structures would need to be constructed for air emissions controls, and a water treatment
facility may be required. Because of the potentially hazardous nature of the trench contents related to the
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possible presence of Army agents or unexploded ordnance, specially trained personnel would need to
conduct the excavation and sorting operation. The rate at which excavation would proceed has been
estimated, for the purpose of this study, to be approximately 6 cubic yards per hour for each backhoe at
the site. At this rate, it would take approximately 2 years to remove the waste material, assuming four
crews, and based on excavating the trench areas considered for this IRA shown on Figure 2-2.
4.2.2.3 Consistency with the rmal Remedv
, .'
Monitoring is thc alternative most consistent with any final remedy. Some construction materials for the
caps in the containment alternative and the temporary waste pile in the source removal alternative may need
to be considered hazardous wastes during the final remedy. Therefore, both containment and source
removal with temporary storage could generate additional materials that may require remediation, while
providing minimal reduction of risk to human health and the environment and limited technical benefit.
In addition, source removal with temporary storage would require rehandling of the waste materials during
final rcmediation, which introduces a second opportunity for incidental cxposure to workers and the
community. rmally, a source removal IRA alternative may not be consistent with the final remedy since
source removal would preclude a final in situ treatment alternative.
L~
4.2.3 Benefit in Terms of Cost
Details of the costs associated with the three IRA alternatives considered technically feasible for this site,
monitoring, containment, and source removal with temporary storage, are presented in the IRA Alternatives
Assessment for this site (WCC 1989a). The alternatives were evaluated to determine whether there is a
benefit in terms of cost in performing an interim action other than monitoring at this time.
Both containment and excavation with temporary storage may increase thc overall cost of cleanup for this
area because thcy gencratc construction matcrials that would requirc subscquent rcmoval and treatment.
In addition, excavation and temporary storagc requires rchandling thc trcnch materials during thc final
remedy. Thcreforc, both containmcnt and excavation may add to thc long-term cost of rcmcdiating this
site.
Monitoring docs not add to long-term costs., and is also the most cost-effective alternative. Consequently,
there appears to be no cost benefit in performing any action othcr than monitoring at this time.
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4.3 CONCLUSIONS
The preferred interim. action for the Army Complex Disposal Trenches is monitoring. No technical or cost
benefit can be identified for performing any additional action at this site at this time. A site-specific
monitoring program will provide continuing information on the impacts of the Army trenches on the
groundwater. A reevaluation procedure will be established to identify changing conditions which may
warrant additional action at this site, and to establish procedures for assessing and implementing an
appropriate action.
1_,.
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5.0
CHRONOLOGY OF EVENTS
The significant events leading to the proposed decision to monitor the Complex Disposal Trenches as
described in Section 6.0 of this report are presented below.
Date
June 1987
Ew:nt
State of Colorado. Shell Oil Company. EP A, and the Army develop and agree,
in a June 1987 report to the Court, to a prospective hot spot list that identifies
candidate Interim Response Actions (1RAs) to be conducted. The hot spot
list consists of five areas (the Section 36 Trenches, the Section 36 Lime Pits,
the M-1 Settling Basins, the Motor Pool Area. and the Railroad Housing Track
in the Rail Classification Yard) referred to as Other Contamination Sources
in the proposed Consent Decree (Section 9.1, paragraph 1). and in the Federal
Facility Agreement, paragraph 22.1 (1).
""/
'"~
February 1988
The State of Colorado. Shell Oil Company. and EP A are initially requested
to identify potential ARARs for this IRA.
.. ;
January 31. 1989
The Army instructs Woodward-Clyde Consultants (WCe) to develop plans
for interim action investigation work in response to the hot spot list. Interim
action investigation work includes the Complex Disposal Trenches.
April 13. 1989
A draft final Task Plan, including the work for the Complex Disposal Trenches,
is submitted by the Army to the Organizations and the State for comment.
April 17, 1989
Field investigatioDS begin for the other contamination sources IRA. Work
includes investigation of the contamin!!lnt source(s) within the Complex
Disposal Trenches.
June 29, 1989
A final Task Plan is issued by the Army with comments incorporated.
September 11, 1989
rIeld investigation completed
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October 5, 1989
November 27, 1989
December 14, 1989
January 26, 1990
~.-
January 26, 1990
.
,
,
.
March 28, 1990
May 1, 1990
'.
. ..
The Army is granted a 2-month extension on the Proposed Decision
Document in order to further address comments on the Draft rlDal
Alternatives Assessment from the Organizations and the State.
Draft rmal Results of Field and Laboratory Investigations Conducted for the
Remediation of Other Contamination Sources Interim Response Action is
distributed by the Army to the Organizations and the State.
The Army announces the results of its reevaluation of existing data, per EP A
comments, in a subcommittee meeting, and discusses the reasons monitoring
is an appropriate interim action for this site at this time. A letter report on
this conclusion is distributed to the Organizations and the State.
rlDal Alternatives Assessment of Interim Response Acti,ons for Other
Contamination Sources - Complex Disposal Trenches, is distributed by lhe
Army to the Organizations and the State with comments incorporated.
Proposed Decision Document for the Interim Response Action at the
Complex Disposal Trenches at the Rocky Mountain Arsenal is distributed by
the Army to the Organizations and the State for comment.
Draft rlDal Decision Document for the Interim Response Action at the
Complex Disposal Trenches at the Rocky Mountain Arsenal is distributed by
the Army to the Organizations and the State with comments incorporated.
Decision Document for the Interim Response Action at the Complex Disposal
Trenches at the Rocky Mountain Arsenal is fmalized.
...'
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6.0
SUMMARY OF 1HE INTERIM RESPONSE AcnON
The preferred alternative for the Army Complex Disposal Trenches is monitoring. No technical or cost
benefit in performing any additional action at this site can be identified at this time. A site-specific
monitoring program will provide continuing information on the impacts of the Army trenches on
groundwater. A reevaluation procedure will be established to identify changing conditions which may
warrant additional action at this site, and to establish procedures for assessing and implementing appropriate
action. The dimensions of this reevaluation procedure are discussed below.
6.1 MONITORING PROGRAM
The monitoring program will consist of periodic sampling and analysis of groundwater from existing wells
upgradient and downgradient of the Complex Disposal Trench area. Additional wells will be required to
adequately monitor upgradient and downgradient water quality in the vicinity of the Complex Disposal
Trenches. The number and location of these wells will be determined during design and implementation
of the IRA. Appropriate indicator analytes and sampling frequency will also be determined during design.
6.2 REEVALUATION PROCEDURE
'"
As information is collected and compared to historical data, a periodic reevaluation will be performed to
determine whether the basis for the present decision has changed. If the basis has changed, then the
decision will be reviewed. A more aggressive action than monitoring may be selected, if a clear and
significant benefit in terms of accelerated cleanup or cost can be demonstrated for such action. Such a
review of the decision will be compatible with and consistent with the process used to reach the original
decision. A procedure for reevaluation to identify changed conditions, and process for considering evidence
of changed site conditions, will consist of the following clements:
~
- Monitoring
. Establishment of a frequency at which data will be rC('Y~mined
. Defmition of a technical data set to be reeY~mined
. Criteria for determining that the basis for the present decision has changed
. Formation of a decision process to determine if mitigative action would yield a benefit
l.
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The following procedure is suggested in this Decision Document and will be fmalized during the design of
this IRA. The flow chart shown in FtgW'e 6-1 parallels the text below.
. Monitoring
Data for reevaluation will be taken from monitoring activities.
. Frequency
Monitoring data will be assembled for reexamination of the Decision F10w Chart at a frequency of
every other monitoring episode. A report will be prepared to document that reexamination.
. Technical Data Set
The data to be included in the reeY~min~tion are:
....
Groundwater gradients
Concentrations of compounds of concern in both upgradient and downgradient wells
Observations of receptor population presence and density
If any of the data change from the previous examination, then the following criteria will be evaluated
to determine whether there is a change in the basis for the alternatives assessment decision.
, .
a~
. Criteria
A change in the basis for the present decision will be indicated if:
Groundwater gradient data indicate groundwater in the bottom of the Complex Disposal
Trenches in two consecutive monitoring episodes.
and,
Increases or decreases in downgradient concentrations cannot be correlated to increases or
decreases in upgradient concentrations in two consecutive monitoring episodes.
and,
.,
Downgradient concentrations are greater than during the IRA alternatives assessment by an
order of magnitude or more.
or.
A notable increase in receptor populations is observed.
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~. r McmilOriDg I
... I Progt'aDI
4~
~.
Do !be Sice
Coadilioas No -
CbaJ ae7 Reevalualioo Report
Ya
..
Has !be Basis
for !be AllUn8lives No -
A.ssessmeDt Decisioo Reevalualioa ~ ..
CbaD3ed7
Yes
~
Is lDere I Significant
Long-Term Benefit (In
TenDS of Cost or No -
Accelented ClCIIIUp) if Reevalllllioa Report ..
80 IRA is Doae N0\If7
Yes
..
Develop a Plao for -- Notify TRC --
r --....
Doc:umenling the
Chan~ Conditions ..
and RevisiDl!be ~ Submit Plan 10 the I --
Decisioa Doc:vment "Prglnizatioas and !be SlIuI ...
~
Review
,
Prepare 8 Revised
Proposed Decision Doc:ument
~
Public/Allene)' Review Process I
~
Prepare I Revised Final
Decisioa Doc:ument
~...l
Job No. : 22238-420
Prepared by: K. A. S.
REEVALUATION PROCESS FOR
ARMY COMPLEX TRENCHES IRA
- ,_..,......
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. Decision Process
If a change in the basis for the present decision is identified, then
A technical reevaluation to determine if mitigative action would yield a clear and significant
benefit in terms of a~lerated cleanup or cost will be conducted using the IRA alternatives
assessment methods and interim action alternatives.
If a benefit will be gained, then a plan for doc:umenting the changed conditions, selecting a
preferred alternative, and revising the decision document, will be submitted to the Organizations
and the State.
The public review process will be reopened: the Technical Review Committee (TRC) will be
notified, public meetings (if needed) will be scheduled, and fact sheets (if needed) will be
prepared.
I
I...
A revised decision document, describing the changed conditions, alternatives considered, and
selected action, will be issued. This decision document will contain the analysis that led to a
revised decision (if the decision is revised).
J
iI...
This process and procedure will be finalized during the design of this IRA.
6.3 REALm & SAFETY PIAN
A Healthy & Safety Plan has been developed for the prevention of occupational injuries and illnesses during
field activities at RMA. This plan addresses health and safety requireme?ts of contractors and their
authorized enforcement and compliance with this plan. The Health & Safety Plan was developed taking
into consideration known hazards as well as potential risks. Comprehensive environmental monitoring and
site-specific personal protection are combined in an effort to best protect workers.
. .
A site-specific Health & Safety Plan for work to be performed on the Complex Disposal Trenches will be
developed.
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7.0
INTERIM RESPONSE AcnON PROCESS
With respect to the Interim Response Action (IRA) for ,the remediation of other contamination sources,
for the Complex Disposal Trenches at Roclcy Mountain Arsenal (RMA), the IRA process is as follows:
1.
The Army issues the proposed Decision Document for the IRA for the interim remediation of
other co~taminSition sources, Complex Disposal Trenches, for a 3O-day public: comment period.
During the 3O-day comment period, the Army will hold one public: meeting addressing the IRA
decision. The proposed Decision Document is supported by an administrative record.
2.
Promptly after the close of the comment period, the Army shall transmit to the other
Organizations, Department of Interior (DOl), and the State, a draft final ~ Decision
Document for the remediation of Other Contamination Sources, Complex Disposal Trenches.
3.
Within 20 days after the issuance of a draft final IRA Decision Doc:ument for the interim
remediation of Other Contamination Sources, Complex Disposal Trenches, an Organization
(including the State if it has agreed to be bound by the Dispute Resolution process, as required
by the FFA, or DOl under the provisions set forth in the FFA) may invoke Dispute Resolution.
4.
After the close of the period for invoking Dispute Resolution, if Dispute Resolution is not
invoked, or after the completion of Dispute Resolution, if invoked, the Army shall issue a final
IRA Decision Document to the other Organizations, DOl, and the State. The Army shall also
notify the public: of the availability of the final IRA Decision Doc:ument with the supporting
administrative record. Only preliminary design work for the IRA may be conducted prior to
the issuance of the fina11RA Decision Document.
The IRA Decision Document for the remediation activity at the Complex Disposal Trenches
will be subject to judicial review in accordance with Section XXXIX of the Federal Facility
Agreement except where such review is barred by Sections 113 and Ul of the Comprehensive
Environmental Response, Compensation and Liability Act (CERCLA) of 1980, as amended,
42 U.s.C. Sections 6913 and 962L
Following issuance of the fina11RA Decision Document, the Army sha11 be the lead party
responsible for designing and implementing the IRA in conformance with the Decision
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Document. The Army shall issue a draft IRA Implementation Document to the DOl, the State,
and the other Organizations for review and comment. The draft Implementation Document
shall include final drawings and specifications, final design analysis, a cost estimate, and IRA
deadlines for implementation of the IRA.
7.
If any Organization (including the State) or the DOl, believes that the IRA is being designed
or implemented in a manner that will not meet the objectives for the IRA set forth in the final
IRA Decision Document, or is otherwise not being properly implemented, it may so advise the
others and shall recommend how the IRA should be properly designed or implemented. Any
Organization (including the State, if it has agreed to be bound by the process of Dispute
Resolution, as required by the FFA, or the DOl under the circumstances defmed in the FFA)
may invoke Dispute Resolution to resolve the disagreement.
8.
As Lead Party for the design and implementation of this IRA, the Army will issue the fmal
Implementation Document, as described above, and will be responsible (or implementing the
IRA in acxordance with the IRA Implementation Docum~nt.
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8.0
APPUCABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS FOR TIlE
REMEDIATION OF 01HER CONTAMINATION SOURCES - SECTION 36 TRENCHES
.. INTERIM RESPONSE ACTION
8.1 INTRODUCTION
These Applicable or Relevant and Appropriate Requirements (ARARs) address a specific area identified
for evaluation for remediation prior to the issuance of a Record of Decision (ROD) for the Onpost Operable
Unit of the Rocky Mountain Arsenal. The remedial actions selected involve monitoring for the Army
trenches and a containment approach involving a physical barrier and cover for the Shell trenches. Some
standards are discussed in general terms, to be further defined as more specific remedial actions are
identified.
8.2 AMBIENT OR CHEMICAL-SPECIFIC ARARS
t...
Ambient or chemical-specific requirements set concentration limits or ranges in various environmental media
for specific hazardous substances. pollutants, or contaminants. Such ARARs either set protective cleanup
levels for the chemicals of concern in the designated media or indicate an appropriate level of discharge
based on health and risk-based analyses and technological considerations.
w
. .
The objectives of this IRA are discussed in the F"mal Assessment Documents. This IRA will be implemented.
prior to the final remediation to be undertaken in the context of the Onpost Operable Unit ROD. The lists
of specific contaminants included in the F"mal Assessment Documents have been completed based upon the
field data concerning these specific sources. The media of concern here are the water and the soils in the
trench areas considered for remediation. However, no ambient or chemical-specific ARARs were identified
concerning levels of contaminants for soils. Since the selected approaches for this IRA do not involve the'
treatment of groundwater from the area of either the Army or Shell trenches, no chemical-specific ARARs
concerning water were selected for this .IRA.
.' .
\ .
8.2.1 Air Emissions
The approaches selected by this IRA do not involve the operation of any treatment system which will result
in air emissions. The capping in the area of the Shell trenches is expected to substantially reduce any current
. emissions coming from the soils in their current state. The monitoring to take place in the area of the Army
trenches will not affect any emissions that may originate in that area, but air monitoring will identify any
potential concerns regarding emissions from this area.
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The standards contained at 40 CFR Part 50 were reviewed and determined to be neither applicable nor
relevant and appropriate to apply as specific limitations to this IRA. These standards apply to Air Quality
Control Regions (AQCR), which are markedly dissimilar from the area within which activity is being
conducted pursuant to this IRA. An AQCR is generally a very large area, covering many square miles. The
trenches cover an extremely small area, far smaller than an AQCR. These standards are not generally
applied to specific emissions sources, such as automobile tailpipes or smokestacks. These considerations lead
to the determination that these ambient air standards are neither relevant nor appropriate to apply as specific
limitations within the context of this IRA.
Other air standards, such as those contained at 40 CFR Parts 60 and 61 and similar state standards such as
those contained at 5 CCR 1001-10, Regulation 8 were not considered as potential ARARs since the IRA will
not include a treatment system which causes air emissions.
8.3 Location-Specific ARARs
c..
Location-specific requirements set restrictions on activities, depending on the characteristics of the site or
the immediate environment, and function like action-specific requirements. Alternative remedial actions may
be restricted or precluded, depending on the location or characteristic of the site and the requirements that
apply to it.
L;
Paragraph 44.2 of the Federal Facility Agreement provides that 8wjJdlife habitat(s) shall be preserved and
managed as necessary to protect endangered species of wildlife to the extent required by the Endangered
Species Act (16 U.S.C. 1531 ~.), migratory birds to the extent required by the Migratory Bird Treaty
Act (16 U.s.C. 703 ~.), and bald eagles to the extent required by the Bald Eagle Protection Act, 16
U.s.C. 688~..
.....
While this provision is not an ARAR, the statutory requirements are ARARs and will be complied with for
purposes of this IRA. Based on where facilities related to this IRA are likely to be located the Army
believes that this IRA wiJJ have DO adverse impact OD any eDdangered species or migratory birds or on the
protectioD of wildlife habitats. CoordinatioD wiJJ be maintained with the U.s. F'1sh and Wlldlife Senice to
ensure that DO such adverse impact arises from implemeDtatioD of this IRA.
The provisions of 40 CFR 6.302(a) and (b) regarding COnstructiOD that would have an adverse impact on
wetlands or be within a floodplain are considered relevant and appropriate to apply in the context of this
IRA. The Army wiJJ comply with these regulations to the maximum extent practicable to avoid construction
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conducted pursuant to this IRA in a manner the would have an adverse impact on wetlands or be within a
floodplain.
The regulations at 40 CFR 230 were reviewed and determined not to be applicable within the context of this
IRA because no discharge of dredged or fill material into waters of the United States is contemplated.
Because these regulations address only the disposal of such materials into the waters of the United States,
which is not contemplated, they are not considered to be relevant and appropriate to apply in the context
of this IRA.
The regulations at 33 CFR 320-330 were reviewed and determined to be neither applicable nor relevant and
appropriate because, they address actions affecting the waters of the United States. No such actioDS are
contemplated within the context of this IRA.
8.4 Action-Specific ARARs
I....
8.4.1 DescriDtion
4":
Performance, design, or other action-specific requirements set controls or restrictions on activities related
to the management of hazardous substances, pollutants, or contaminants. These action-specific requirements
may specify particular performance levels, actions, or technologies as well as specific levels (or a
methodology for setting specific levels) for discharged or residuaJ chemicals.
8.4.2 Construction OccurrinlZ Incident to the IRA
8.4.2.1 Air Emissions
On the remote possibility that there may be air emissions during the course of the construction associated
with this IRA, the Army has reviewed all potential ambient or chemical-specific air emission requirements.
As a result of this review, the Army fOUDd that there are, at present, no National or State ambient air quality
standards currently applicable or relevant and appropriate to any of the volatile or semivolatiles chemicals
in the groUDd water fOUDd in the area in which construction is contemplated.
In the context of this IRA, there is only a very remote chance of any release of volatiles or semivolatiles and,
even if such a release did occur, it would only be intermittent and of very brief duration (because the activity
that produced the release would be stopped and modified appropriately if a significant air emission, based
upon specific standards contained in the Health and Safety Plan, was detected by the contrador's air
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monitoring specialist). The Army has significant experience with the construction of extraction and
reinjection wells and has not experienced any problems from air emissions during construction of such
facilities. Since minimal excavation of saturated material is ,anticipated, it is not believed that air emissions
are likely to occur, as they might if large amounts of saturated material were excavated and necessitated
drying. The site-specific Health and Safety Plan will adequately address these concerns. This plan to be
developed for use in the IRA will detail operational modifications to be implemented in the event monitoring
detects specific levels of such emissions.
, .
The National Emissions Standards for Hazardous Air Pollutants (NESHAPS) were evaluated to determine
whether they were applicable or relevant and appropriate to apply in the context of construction of this IRA.
These standards were not considered applicable because they apply to stationary sources of these pollutants,
not to construction activity. These standards were not considered relevant and appropriate because they
were developed for manufacturing processes, which are significantly dissimilar to the short-term construction
activity contemplated by this IRA.
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The provisions of 40 CFR 50.6 will be considered relevant and appropriate. This standard is not applicable
because it addresses Air Quality Control Regions, which are areas significantly larger than and different from
the area of concern in this IRA. Pursuant to this regulation, there will be no particulate matter transported
by air from the site beyond the installation boundary that is in excess of 50 micrograms per cubic meter
(annual geometric mean) and the standard of 150 micrograms per cubic meter as a maximum 24-hour
concentration will not be exceeded more than once per year.
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The provisions of Colorado Air Pollution Control Regulation No. 2, concerning odor emissions is considered
relevant and appropriate to apply at the installation boundary.
8.4.2.2 Worker Protection
, -
The provisions of 29 CFR 1901.120 are applicable to workers at the site because these provisions specifically
address hazardous substance response operations under CERCI.<\. It should be noted that these activities
arc presently governed by the interim rule found at 29 CFR 1910.120 but that by the time IRA activity
commences at the site, the final rule found at 54 FR 9294 (March 6, 1989) will be operative. The final rule
became effective on March 6, 1990.
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8.4.2.3 General Construction Activities
The following performance, design, or other action-specific State ARARs have been identified by the Army
as applicable:
Colorado Air Pollution Control Commission Regulation No. 1, 5 CCR 1001-3, Part m(D)(2)(b),
Construction Activities:
a.
Applicability - Anainment and Nonanainment Areas
b.
General Requirement
u
Any owner or operator engaged in clearing or leveling of land or owner or operator of land
that has been cleared of greater than one (1) acre in nonanainment areas for which fugitive
particulate emissions will be emined shall be required to use all available and practical
methods which are technologically feasible and economically reasonable in order to
minimi7~ such emissions, in accordance with the requirements of Section m.D. of this
regulation.
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Applicable Emission Limitation Guideline
Both the 20% opacity and the no off-property transport emission limitation guidelines shall
apply to construction activities; except that with respect to sources or activities associated
with construction for which there are separate requirements set forth in this regulation,
the emission limitation guidelines there specified as applicable to such sources and activities
shall be evaluated for compliance with the requirements of Section m.D. of this regulation.
(Cross Reference: Subsections e. and f. of Section m.D.2 of this regulation).
, .
d.
Control Measures and Operating Procedures
. .
Control measures or operational procedures to be employed may include but are Dot
nccessarily limited to planting ~getatioD cover, providing synthetic cover, watering,
chemical stabilization, furrows, compacting, minimi7:ing disturbed area in the winter, wind
breaks, and other methods or techniques.
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Colorado Ambient Air Quality Standards, 5 CCR 1001-14, Air Quality Regulation A, Diesel-Powered Vehicle
Emission Standards for Visible Pollutants:
a.
No person shall emit or cause to be emitted into the atmosphere from any diesel-powered
vehicle any air contaminant, for a period greater than 10 consecutive seconds, which is of
such a shade or density as to obscure an observer's vision to a degree in excess of 40%
opacity, with the exception of Subpart B below.
b.
No person shall emit or cause to be emitted into the atmosphere from any naturally
aspirated diesel-powered vehicle of over 8,500 lbs gross vehicle weight rating operated
above 7,000 feet (mean sea level), any air contaminant for a period of 10 consecutive
seconds, which is of a shade or density as to obscure an observer's vision to a degree in
excess of 50% opacity.
Co
Diesel-powered vehicles exceeding these requirements shall be exempt for a period of 10
minutes, if the emissions are a direct result of a cold engine start-up and provided the
vehicle is in a stationary position.
d.
This standard shall apply to motor vehicles intended, designed, and manufactured primarily
for use in carrying passengers or cargo on roads, streets, and highways.
Colorado Noise Abatement Statute, CoR.S. Section 25-U-103:
a.
Each activity to which this article is applicable shall be conducted in a manner so that any
noise produced is not objectionable due to intermittence, beat frequency, or shrillness.
Sound levels of noise radiating from a property line at a distance of twenty-five feet or
more there from in excess of the db(A) established for the following time periods and
zones shall constitute prima facie evidence that such noise is a public nuisance:
7:00 a.m. to 7:00 p.m. to
~ next 7:00 p.m. next 7:00 a.m.
Residential SS db(A) SO db(A)
Commercial 60 db(A) SS db(A)
Light Industrial 70 db(A) 6S db(A)
Industrial 80 db(A) 75 db(A)
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b.
In the hours between 7:00 a.m. and the next 7:00 p.m.. the noise levels permitted in
subsection (1) of this section may be inaeased by ten db(A) for a period of not to exceed
fifteen minutes in anyone-hour period.
Co
Periodic:, impulsive, or shrill noises shall be considered a public nuisance when such noises
are at a sound level of five db (A) less than those listed in Subpart (a) of this section.
d.
Construction projects shall be subject to the maximum permissible DOise levels specified
for industrial zones for the period within which construction is to be completed pursuant
to any applicable construction permit issued by proper authority or, if no time limitation
is imposed, for a reasonable period of time for completion of the project.
e.
For the purpose of this article, measurements with sound level meters shall be made
when the wind velocity at the time and place of such measurement is not more than five
miles per hour.
f.
In all sound level measurements, consideration shall be given to the effect of the ambient
noise level aeated by the encompassing noise of the environment from all sources at the
time and place of such sound level measurements.
In substantive fulfillment of Colorado Air Pollution Control Commission Regulation No. 1, this IRA will
employ the specified methods for minimizing emission from fuel burning equipment and construction
activities. In substantive fulfillment of Colorado's Diesel-Powered Vehicle Emission Standards, no diesel
motor vehicles associated with the construction shall be operated in a manner that will produce emissions
in excess of those specified in these standards.
The noise levels pertinent for construction activity provided in c.R.S. Section 25-12-103 will be attained in
accordance with this applicable Colorado statute.
8.4.2.4 Wetlands Implications
Through estimation of the general area where any construction would occur or facilities be located, the Army
does Dot believe that any wetlands could be adversely affected. However, until a final design is selected, it
cannot be definitively determined that DO impact on wetlands will occur. If the final site selection and/or
design results in an impact on wetlands, the Army will review the regulatory provisions concerning wetlands
impact, generally identified as relevant and appropriate in the discussion of location-specific ARARs above,
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and other appropriate guidance, and wiUproceed in a manner consistent with those provisions. Coordination
will be maintained with the u.s. FISh and Wildlife Service concerning any potential impacts on wetlands.
8.4.2.5 Groundwater Monitorini
The Army has determined that the substantive provisions of the regulations contained in 40 CFR S 264.97,
and any provisions of 6 CCR 1007-3, S 264.97 which are more stringent than the federal regulations, are
relevant and appropriate to apply to the groundwater monitoring which is to occur pursuant to this IRA.
Pursuant to CERClA Section 121(e), 42 U.s.C. S9621(e), no federal, state or local permit is required for
the groundwater monitoring to be conducted. The specific: monitoring program will be developed later in
the IRA process and may utilize some number of the existing monitoring wells on the Arsenal, sampling
conducted under the Comprehensive Monitoring Program, the addition of new wells and/or sampling
requirements or any combination of these approaches in order to fulfill the substantive requirements of these
regulations.
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8.4.2.6 Construction of Physical Barner and Cover for Shell Trenches
i.J
The substantive standards contained in 40 CFR S 264.310, specifically those requirements contained in
subsections a(2)-(4) and b(l) and (4), which describe the necessary standards and actions concerning landfill
covers, are considered relevant and appropriate to apply to the construction and continued operation of this
cover.
8.4.2.7 Land Disposal Restrictions and Removal of Soil
There are no action-specific ARARs that pertain to the excavation of soil during the construction associated -
with this IRA.
EPA is currently developing guidance concerning the Land Disposal RestrictioDS (LDR). While guidance
is limited, the Army has not, at this time, made a determination that any waste subject to LDR will be
present in the soil removed by this IRA. Further EPA guidance concerning the applicability of LDRs to
CERClA actioDS is likely to be issued prior to the implementation of this IRA and the Army will review
such guidance as it is released. If it is determined that a waste subject to LDR is present, the Army will act
in a manner consistent with EP A guidance then in effect for the management of such within the context of
CERClA actions.
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Soil removal from the area will be performed in accordance with the procedures set forth in the Task No.
32 Technical Plan, Sampling Waste Handling (November 1987), and EPA's July 12, 1985, memorandum
regarding "EP A Region vm Procedure for Handling of Materials. from Drilling, Trench Excavation and
Decontamination during CERCLA RIfFS Operations at the Rocky Mountain Arsenal.. While not an
ARAR, EPA's July 12, 1985 guidance memorandum applies to this action as a TBC. Soils, not included for
further treatment, generated by excavation during the course of this IRA, either at surface or subsurface,
may be returned to the location from which they originated (i.e.,1ast out, first in). Any materials remaining
after completion of ba~1cfi1li"g that are suspected of being contaminated (based on field saeening
techniques) will be properly stored, sampled, analyzed, and ultimately disposed as CERCLA hazardous
wastes, as appropriate.
I .~
For material determined to be hazardous waste resulting from construction activities, substantive RCRA
provisions are applicable to their management. These substantive provisions include but are not limited to:
40 CFR Part 262 (Subpart C, Pre-Transport Requirements), 40 CFR part 263 (Transporter Standards),
and 40 CFR Part 264 (Subpart I, Container Storage and Subpart 1., Waste Piles). The specific substantive
standards applied will be determined by the factual circumstances of the accumulation, storage or disposal
techniques actually applied to any such material.
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8.4.2.8 Soil Treatment and DisDOSal
These proposed remedial actions do not include any significant possibility of onsite or offsite disposal of
soils or contaminated material excavated pursuant to this IRA. The selected alternative of monitoring for
the Army trenches only involves minimal excavation and should result in only small amounts of excavated
soil remaining to be handled as discussed above. The containment structures contemplated in connection
with the Shell trenches will result in some excavation of soil. However it is intended that the excavated soil
be retained in the area of the trenches, covered by the containment structures which are to be built pursuant
to this IRA. ID the event that some material is later considered (or disposal, AR.ARs (or such activities have
been generally identified, with more specific analysis to follow after any specific disposal determination is
made. Onsite disposal o( material is Dot coDtempJated. For offsite disposal of hazardous material the
administrative and substantive provisions o( 40 CFR Part 262, Subparts A,B,C and D, and any provisions
of 6 CCR 1007-3, Part 262, Subparts A,B,C and D which are more stringent than the corresponding federal
regulations, are considered relevant and appropriate.
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8.S COMPUANCE WITII THE OTHER ENVIRONMENTAL lAWS
As is evident from the various portions of this document, this IRA was prepared in substantive compliance
with 40 CFR 1502.16 (the regulations implementing the National Environmental Policy Act of 1969).
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9.0
SCHEDULE
The Draft Implementation Document is scheduled for completion on October 1, 1990. The construction schedule
will be contained in the Draft Implementation Document for this Interim Response Action (IRA). This
milestope has been developed based upon the r1Jlal Assessment Document and the assumption that no dispute
rcsolution will occur. If events that necessitate a schedule change or extension occur, the change will be
incorporated in accordance with the Federal Facility AgreemenL
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10.0
CONSISTENCY WITH TIm FINAL REMEDIAL ACI10N
The Federal Facility Agreement states that all Interim Response Actions (IRAs) shall "to the maximum extent
practicable, be consistent with and contribute to the efficient performance of F"mal Response Actions" (paragraph
22.5).
The seleaed alternative, by providing additional site characterization information which will be utilized in
developing an appropriate future response action, either as part of the final remedy or prior to the final remedy,
if appropriate, will be consistent with any F"mal Response Action.
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(11111an.4200) (TRENCHI0JRA) (03/ZA/90) (RMA)
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REFERENCES
Ebasco Services, Ine. 1989a. March. Draft Fmal Remedial Investigation Report, Central Study Area. Version.
2.1. RIC89166R06.
Ebasco Services, Ine. 1989b. June. Proposed Fmal Remediation Investigation Report, Volume XI, North
Central Study Area. Version 3.2. RIC89166R07.
Environmental Science and Engineering, Ine. 1988a. January. Fmal Phase I Contamination Assessment Report,
Site 36-17, Complex Disposal Activity, Version 3.2, Task No. 1. RIC 88013R05.
Environmental Science and Engineering, Ine. 1988b. September. Fmal Phase U Data Addendum, Site 36-17,
Complex Disposal Activity, Version 3.1. RIC 88013ROSA.
Woodward-Clyde Consultants. 1989a. Fmal Alternative Ass~ccment of Interim Response Actions for Other
Contamination Sources Complex Disposal Trenches.
Woodward-Clyde Consultants. 1989b. Fmal Results of Field and Laboratory Investigations Conducted to
Evaluate Interim Response Actions for Other Contamination Sources.
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Utfl"ED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION VII
999 18th STREET - SUITE 500
DENVER, COLORADO 80202-2405
Ref:
8HWM-FF
Mr. Donald L. Campbell
Office of the 'proqram Manaqer
Rocky Mountain Arsenal
ATTN: AHXRM-PH
Commerce City, Colorado 80022-2180
Re: Rocky Mountain Arsenal (RHA)
Proposed Decision Document for
the Interim Response Action
for the Complex Disposal
Trenches, January 1990.
Dear Mr. Campbell:
We have reviewed the above referenced report and have the
enclosed comments.
Our major concern is the lack of a stronq technical
ev uation to support monitorinq and periodic reevaluation of the
site as the preferred alternative. The complex disposal trenches
are a source of qroundwater contamination. Whether the trenches
are a siqnificant source has not been thoroughly evaluated.
Although the Army was qiven a two month extension on this IRA to
further evaluate the existing data, it appears that they have
used the time to rewrite the Alternative Assessment Document to
select a different alternative without further technical
evaluation. There exists a Draft Alternative Assessment Document
which presents one preferred alternative and a final version of
the sa~e document in which a different preferred alternative is
presented. The major difference in the two documents is
differinq subjective points of view. The monitorinq alternative
would be more defensible if there was a better technical
evaluation in the Final Alternative Assessment Document.
The Final Alternative Assessment Document for this IRA does
not evaluate accelerated cleanup of groundwater but the Decision
Document eliminates it from further consideration in the
Technical Benefits Section (refer to specific comment 2) via
conclusions reached without performing a supporting evaluation.
The impact of these trenches on the Denver Formation is not
evaluated nor is a commitment made to monitor the Denver in the
preferred alternative.
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Please contact Linda Jacobson at (303) 294-7093, if you have
questions on this matter.
Sincerely,
~,.
I ~
Connall Mears
EPA Coordinator for RMA
Cleanup
Enclosure
cc:
Col. Dan Voss, RMA-PMO
J. D. Smith, RMA-PMO
Jeff Edson, CDa
David Shelton, coa
Vicky Peters,CAGO
Major Larry Rouse
Chris Hahn, Shell
Georqe Roe, Shell
Robert Foster, OOJ
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APPENDIX A
COMMENTS AND RESPONSES
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RESPONSE TO COMMENTS FROM THE EPA
ON THE PROPOSED DECISION DOCUMENr FOR THE INTERIM RESPONSE AcnON
FOR THE ARMY COMP' Py DISPOSAL TRENM{F~
General Comment (summarizinsr the cover lette~')
There is a lack of strong t~h"ical evaluation to suppon monitoring and periodic reevaluation of the site as
the preferred akenwiYe. .
Response:
The tedmica1 approach used to evaluate the need for mitigative action at the site wu to
develop a conceptual model of the site and test this with field sampling data; if the concepaW
model was supponed by the aampliDg data. then the site was considered to be sufficiently
characterized to make a determination of whether or not mitigative action would yield a dear
and significant benefit. This approach possible beause of the substantial body of
technical information Crom contamination ~cc"'ent repons, the remedial investigation, and
the CMP. These data provided a sound inductive basis for the development of the conceptual
model
The conceptual model holds that the Complex Disposal Trenches. are located on the eastena
Cringes of a major flow system Crom the South Plants area, moving nonh then northwesterly,
to Basin A Neck. The trenches ascend a bedrock high that lena as a barrier to ea.uerly
groundwater flow. The trenches are intermittently in contact with groundwater contaminated
from upgradienr -'Ources, are usually unsaturated, and therefore are not continuous
contaminant contributors to the major flow system. Mitigative action would be indicated if
additional data suggested that the trenches were major contributors to the contaminant load
of the main south-DOnh flow system and some benefit in terms of accelerated cleanup or cost
could be shown (a proposed reevaluation process is presented in Section 6.0 of this Decision
Document).
Field sampling coasisted of trenching, geophysics, and weD development in the immediate
viciniry of the trcnches. These data confirmed that the trenches arc usually unsaturated and
that DO firm conclusion can be reached about the correspondence betweeD contAmin."t 1ewIs
in and adjacem to the trenches and the coat.mi"."t levels in dowagradient waters. Furtber,
the presence of the bedrock high and its function as a hydraulic barrier were gcnenlly
confirmed. Thercfore, since field data confirm a conceptual modcl de...eloped out of extensm,
eYisti"g data, by logical infercnce the AnDy concluded that mitigative actioD at this time
would DOt yield a dear and sigDificaDt benefit in tel'lDl of acceJerated cleanup or cost. The
Army believes that this logic is sound and the data that supported its de\'e1opmenr are also
sufficient to support this conclusion.
Comment!:
Specific Commeats.
..
Response:
Page 4-3, Section 4.2.1, first paragraph. The text indicates that the site docs DOt appear to
be posing a ~8"if1L"!1"t risk to human health and the envirODlDCDL There is not enough data
presented in the Alternaa...e ~u"'CDt to reach that conclusion in. regards to the
environment. The Den\'er Formation pathway has not been evaluated, which makes the
stated CODClusion prematUre.
The evaluation of risk at this site is based on consideration of source, pathways, and
receptors. Human bealth risk was judged to be insignificant beause the source tcrm &om
the Complex Disposal TreDchcs appears to be OYerWhelmed by other source terms origjftJllti"g
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upgradient, and because there arc no human receptors directly exposed or imminently
threatened with exposure to contaminants originating in the Complex Disposal Trenches.
This judgement is based on a qualitative as~ssment of risk factors, and is apparently'
acceptable to the EP A In like fashion, the asse~c.ment of environmental risk (i.e. risk to
biota) was qualitative, considering the same types of risk factors: source, pathways, and
receptors. The reasoning used is summarized below.
.
Source. The source term for environmental risk is the same as for human risk: buried
confaminants that are in occ:asional contact with groundwater. The Complex Disposal
Trenches source is markedly smaller in magnitude than upgradient sources to the south..
that are continuously contributing groundwater contaminants migrating north-northwest.
Field tests did not demonstrate a significant worsening of these contaminant plumes
downgradient of the Complex Disposal Trenches. Therefore, the Army trenches do
. not appear to be major contributors to the principal contaminant plumes in the area.
.
Pathways. The IRA Alternative Assessment for this site reviewed the pathways for each
class of contaminant detected or reported in the Complex Disposal Trenches, and
concluded that the most likely pathway to the biosphere is groundwater. While several
of the compounds of concern are reported to be susceptible to adsorption to soils, the
general absence of plant life suggests that uptake of contaminants by plants will not be
a major pathway.
..
Receptors. Non-human receptors in the area would consist of plant communities,
small animals such as prairie dogs that depend on the plant communities, and predatory
species such as eagles that prey on smaller animals. The general absence of plant life
has been established. Larger plant-eating species such as the ungulates are unlikely
users of the area because the forage is sparse compared to other nearby areas of the
Arsenal. Prairie dogs and other rodents were largely extirpated in this area by an
earlier program that was concerned that burrowin~animals would become contaminated
and contribute to bioconcentration of contaminants in higher species. Because of the
absence of small animal populations, this study concludes that higher species (the
eagles) are not likely to be affected significantly by buried contaminants in the Complex
Disposal Trenches.
The source term from the Complex Disposal Trenches area does not appear to be significant
in comparison with other sources in the immediate area; the principal pathway appears to
be groundwater, which is inaccessible to any would-be environmental receptors; and therr.
is a general absence of environmental receptors. Therefore, the risk to the environment from
the Complex Disposal Trenches is judged qualitatively to be low.
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The comment on the lack of evaluation of the Denver Formation pathway as a contributor
to short-term (IRA timcframe) environmental risk is not understood. ContaminAnt
movement, per se, through the Denver has not been studied as part of this IRA. Although
several Denver Formation monitoring wells downgradient of the Complex Disposal Trenches
did show groundwater contamination, upgradient Denver Formation monitoring wells do not
exist to allow determination of the contamination source. If contalftinant movement was
identified, it would resemble the alluvial contaminant plumes in tWo important ways: it may
be dominated by large sources upgradient of the Complex Disposal Trenches, and it would
be largely inaccessible to environmental receptors in the area of the Complex Disposal
Trenches. For these reasons, if the Denver Formation pathway existed, it would DOt be
judged to be a major contnoutor to environmental risk during the IRA timeframe in the
general area of the Complex Disposal Trenches.
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Comment 2:
Response:
Commcnt 3:
Rcsponsc:
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Commcnt 4:
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Response:
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:.. This
.itional
Page 4-3, Section 4.2.1, sccond paragraph. The argume.:.i. l:i prc,)C=~~d that mo'
would be required to be trcatcd if a containmcnt system were installcd for thc tre~
argument doc.s not comparc thc projected volu:: of containmcnt materials to th
volume of material to be trcated if no action i& oakcn (only furthcr monitoring,
If a containment system were installed for the Army trcnches, clean mate- used for
consuuction would come in contact with the contaminated materials in the \es. The
consuuction matcrials may subsequcntly be considcred contaminated and rr .reatment
during thc final remediation. If monitoring is the interim action implcme. . this site,
con'.lIIm.n.. may migrate &om thc trenches with the groundwater; This ml.lll wiD ~
place in aD aquifer already COn'Amm.'ed &om upgradient sources. T .:.here is DO
UDCODtJlminJl'ed media that will be affected by thc possible migratioD of CC. 'linAn't &om.
the Army trenches during thc tcrm of this IRA. In othcr words, the Army D~~Cves that the
volume of con'JlminAted media to be treated would Dot ina-ease UDdcr thc monitoring
alternative.
Page 4-4, Section 4.2.2.1, second paragraph, please providc rcfercnce to sampling data to
support thc assertiOD that only low levels of residual organic contAmination arc present in
thc trcnches. .
Rcference to thc rmal IRA Altcrnatives Ass~c~mcnt for this sitc has becn addcd (WCC
1989a). Appendix B of the rcport includcs thc soil data &om thc Phase I and Phase II ficld
investigations (ESE 1988a and 1988b) and thc Spring 1989 investigation (WCC 1989b). AD
Appefidix B has been addcd to this Decision Documcnt, and includes soil and groUDdwatcr
contamination data.
Pagc 4-4, Section 4.2.2.1, third paragraph. Thc tcxt discusses groundwater extraction and
trcatmcnt and rcaches a conclusion about the significance of the amount of contaminants that
could be rcmoved Crom the groundwater. Since groundwater extraction and treatment was
not evaluated in the Alternatives Assessment Documcnt, thc conclusion is without basis or
foundation to be discussed in this documcnL
Further, we support the development of Dew monitoring wells and data to support the
asscrUon that DO contAlllinlnts arc being rel~a.sed &om these: uenchea which would iDiluc:nce
the future groundwater remedial actions to be selected for the final deanup of SectioD 36
groUDdwater.
. Contrary to the assertiOD in this comment that groundwater extraction'
not evaluated in the Alternative ~'Iment Document, Section 3.2.4 of tl
~nlllent Document is titled 8Groundwater Extraction and Treatment,
aD evaluation of this topic.
2tmeDt was
. Alternative
. oc.s contain
. Disposal
the area,
ter flows
sources
Earlier secUons of the A'~Clllent Document demcmsuate that the C.
Trenchea are located on the margins of the principal groundwater flows L
are perally boUDded OD the northeast by . bedrock high, that the alluvial gro..
trend DOrthwest, and that CODtLaiDant plumCl in this area are domilw.
upgradicDt of the Campa DispoW Trcncbea.
Given that it is established, OD the basis of. site conceptual model that is confirm by field
testing, that the Complex Disposal Trenches are DOt major contributors to the Ct "lIIinAnt
plume eveD though the trenchea con'SIIifting con'SliminAnts are someUmCl in COL;Act with
groUDdwater, it would make little sense to identify groundwater extraction and treatment as
a major alternative short-term strategy that would prevent the spread of CODtSliminSlintl. Crom
A-S
-------
Comment 5:
<:- ~
Response:
".\
Comment 6:
Response:
Comment 7:
Response:
Woodward.Clyde Consultants
the trenches. The scale of northwest-trending contllminllnt plumes in this area is recognized
by the Basin A Neck groundwater remediation IRA; another groundwater remediation IRA
of a comparatively minor source on the eastern fringe of Basin A would not make a
significant contribution to short-term cleanup of the alluvial aquifer in the area, and would
not be cost effective.
The Assessment Document discusses groundwater extraction and treatment in relation to
containment options for the Complex Disposal Trenches. U the access of confllminllnts in
the trenches to pathways and receptors was judged to be serious enough to merit action (it
was not so judged), then one form of action over the short-term was identified to be
containment with a physical barrier system that could consist of a cap, and/or slurry wall
and/or sheet pilings, with a groundwater extraction system that would maintain a hydraulic
gradient towards the disposal trenches and impede the migration of contaminants outward
or through these barriers. Any waten produced in this gradient-inducing scheme would be
treated.
The conclusion reached about the significance of the amount of contaminants that could
be removed from the groundwater is reached on the basis of straightforward logic that is well
presented in the Assessment Document. No change in the wording of the Assessment
Document or the Decision Document is proposed.
Page 4-5, it is stated that there are no monitoring wells in the saturated bedrock upgradient
from the Anomalous Areas B and C. This indicates that further characterization is needed;
thus, the installation of further monitoring wells is required for this IRA.
The Army agrees. Additional monitoring wells will be installed as part of the preferred
alternative (i.e. monitoring) for this IRA.
Page 4-5, the text needs to discuss how the monitoring alternative as presented is a further
step than the "no action" alternative. Further, please discuss whether it is believed that
quarterly monitoring to be performed as part of the CMP will alone be sufficient to
adequately assess further contaminant releases.
Section 4.3 .Conclusions" has been added to the text and disc:usscs how the monitoring
alternative is a further step than "no action". A site specific monitoring program will be
developed during the design of this IRA to fully address the objectives of the IRA. The
statement that "[g]roundwater monitoring wells may be able to be sampled in conjunction
with the [CMP]" is meant to describe a possible mechanism for conducting the sampling.
not to imply that the cunent CMP is necessarily sufficient for the purposes of this I;RA
Although quanerly sampling was used for costing purposes in the IRA Alternatives
As~n'"ent for this site, the actual sampling frequency needed to meet the objectives of this
IRA will be determined during design. Section 6.0 of this Decision Document has been
revised to define the basis for site reevaluation during this IRA.
Page 4-6, Section 4.2.2.3. The text states that monitoring is the only alternative which is
completely consistent with the final remedy. Other IRAs have implemented actions other
than monitoring and have been determined to be consistent with the final remedy. Section
22.S of the FFA does not require that an IRA be completely consistent with the tiDal remedy.
Momtoring is the action most consistent with the fiDal remedy at this site because no
technical or cost benefit in performing any other action at this time can be identified.
Consistency with the final remedy was not the only criteria used to determine that monitoring
is the preferred IRA for this site at this time. Although other actions may be consistent with
C~JII) C-\...) (a3/:IoIfIIO)
-------
Comment 8:
Respousc:
Comment 9:
Response:
,"...
Comment 10:
"..'
Response:
-...~
WoocIward-CIyd&ConsuItants .
a final remedy, and the FFA does not require an IRA to be completely cozWs.-':1t with the
final remedy, monitoring is the only interim action completely consistent.. any final
remedy at this site. The text has been changed to state that "[m]oDitoring is . 1lternative
most consistent with any final remedy:
Page 4-6, Section 4.2.3, Cost Benefit Analysis. A true cost-benefit analysis v. .)t performed
in the Alternative Ass~n"1ent Document. The analysis only determined t! monitoring is
the lowest cost alternative to implement now, but the future cost impaa vi deferring the
cleanup was Dot determined or evaluated. Based OD those analysis results, no real aaalysis
of benefit caD be made.
The intention in the Alternative Nsrcc"'ent Document is to evaluate whether there is a clear
cost benefit in performing an IRA now, rather than to conduct a detailed cost-benefit
analysis. The title of subsection 4.2.3 has been changed to -Benefit in Terms of Cos&,. aDd
the text has beeD modified to clarify this poinL
Page 6-1, please state what defines a "clear and significant benefit in implementing a more
extensive IRA8 in the site reevaluation phase for this IRA. Further, we request a statement
defiDing the basis of reevaluation.
A clear and significant benefit in implementing a more extensive IRA will be attained if 1)
the interim action will result in an acceleration of the final cleanup, or 2) the interim action
will reduce long-term costS. Section 6.0 of the Decision Document b2! bee.n revised to define
the basis of reevaluation.
Page 8-1, we agree that chemical-specific ARARs are not appropriate for the selection of
monitoring without treatment for this location and point in time. We request the
identification of "driver compounds" whose levels will be monitored and the establishment
of "trigger levels" which will dictate further action.
~river compounds," or indicator analytes, will be identified during the design of this IRA.
The Army believes that 8trigger levels8 are not appropriate to dictate further actioD. A
reevaluation process has been described in Section 6.0 of the revised DecisioD DocumCDL
Comment 11: Page 8-1, please provide details of the air monitoring in this area. both the location and
types of air monitoring being implemented. Please assess whether the air moniton are
sufficiently positiODed to monitor air releases from these areas.
Response:
. .
The CMP has two air monitoring statiODS in SectiOD 36. For detaDs of the air monitoring
program, see R.L. Stoller, ComDrehensive Monitorinsr: Pr0if3m Draft rma! Technical Plan.
Air Ouali~. August 1988, RIC 8S34OROl. This program has been judgce be sufficieDt to
monitor releases from th: buried materials in the Complex Disposal TrcL uea. The 0Dly
air releases that may OC:C:OU' during implemeDtatioD of the monitoring alten. .~ for this IRA
would be due to well Vtctall"tioD. These possible minor air releases woo. 'e monitored
using health aDd safety equipment (e.g., PIDs, OVAl) as has been done dw ' otb~.. well
iftst~IISILtiOD at RMA.
CommeDt 12:. Page 8-2, the Endangered Species Act, the Migratc~T Bird Treaty Act, and thl 3ald Eagle
ProtectioDAct ICfte asARARs, per EPA Guidance (C£RCLA Compliaacc wit.' Jthcr Laws
Manuals, Volumes land U).
#.
Response:
These statutes are idcfttified as ARAR.s in thc revised DecisioD Document.
(~ (-wa) (fD/2'/90)
-------
. .~~-
Shell Oil Company
.
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,j c, J..L.I
/o~ )"
tJN
..
One She" Plaza
PO. Box 4:320
!-ioulton. Texas 7i2,0
February 23, 1990
Office of the Program Manager for Rocky Mountain Arsenal
ATTN: AMXRM-PM: Mr. Donald L. Campbell
Rocky Mountain Arsenal, Building 111
Commerce City, Colorado B0022-21BO
Dear Mr. Campbell:
Enclosed herewith are Shell Oil's comments on Proposed Decision Document,
ArmY.Complex Disposal Trenches, January 1990.
Sincerely,
-~~
George Roe
Technical Manager
Denver Site Project
',..!
/ajg
Enclosure
cc:
(w/enclosure)
Office of the Program Manager for Rocky Mountain Arsenal
ATTN: AMXRM-1A: Mr. J. D. Smith
Rocky Mountain Arsenal, Building 111
Commerce City, CO B0022-2180
Office of the Program Manager for Rocky Mountain Arsenal
ATTN: AMXRM-RP: Mr. Kevin T. Blose
Rocky Mountain Arsenal, Building 111
Commerce City, CO 80022-2180
Mr. Bradley S. Bridgewater
Department of the Army
Environmental Litigation Branch
Pentagon Room 1C4BO
ATTN: DAJA-ELL: Major Lawrence
Washington, DC 20310-2210
E. Rouse
RmA
0.3.3,
qO <# O~
,/~
-------
cc:
Victoria L. Peters, Esq. .
Assistant Attorney General
CERCLA Litigation Section
1560 Broadway, Suite 250
Denver, CO 80202
Mr. Robert L. Duprey
Director, Hazardous Waste Managem~nt Division
U.S. Environmental Protection Agency, Region VIII
One Denver Place
999 18th Street, Suite 500
Denver, CO 80202-2405
Mr. Connally Mears, 8HWM-SR
EPA Coordinator for Rocky Mountain Arsenal
US EPA, Region VIII, Superfund
999 18th Street, Denver Place, Suite 500
Denver, CO 80202-2405
, ,
Mr. Thomas P. Looby
Assistant Director
Colorado Department of Health
4210 East 11th Avenue
Denver, CO 80220
Mr. Jeff Edson
Hazardous Materials and Waste
Colorado Department of Health
4210 East 11th Avenue
Denver, CO 80220
Management Division
. '
~
-------
Woodward-Clyde Consultants
RESPONSE TO COMMENTS FROM ~m:T 1. on. COMPANY
ON THE PROPOSED DECISION DOCUMENT FOR THE INTERIM RESPONSE ACTION
FOR THE ARMY COMPI FX DISPOSAL TRENCFF~
Comment 1:
General Comments
Response:
Comment 2:
Response:
Shell concurs with the selection of monitoring as the most appropriate alternative for the
Army trenches at this time.
Shell's comment is noted.
Shell agrees with the Army commitment to monitoring made at the recent public meeting,
and' recommends focusing on selected indicator analytes at or outside the boundaries to
detect lateral or vertical migration over time. The risk posed by this site is still not defined
clearly enough to conclude that monitoring in a .status-quo. mode will be sufficient for the
life of the IRA. Further characterization of the trench contents is not needed for the IRA,
and should be done separately if needed by the Feasibility Study. .
Indicator analytes, or driver compounds, will be selected during the design of this IRA. The
Army agrees that moni[oring may not be sufficient for the life of the IRA. Periodic re-
cvaluation will be performed to cvaluate the bencfit of additional interim action. Thc Army
also agrees that further characterization of the trench contents should only be done if needed
for the Feasibility Study.
Comment 1:
SDecific Comments
On page 1-1, fmal sentcnce, recommend adding 8. . . for migration of contaminants:
. -4
Responsc:
Commcnt 2:
Rcsponse:
Commcnt 3:
Response:
Commcnt 4:
Response:
Comment 5:
Response:
Agreed. The text has been changed.
On Pagc 2-1, second paragraph, recommcnd changing thc sequcncing of ICP metals, arsenic,
and mercury to match that on Pagc 2-3, last sentence.
The text has been changed.
Page 2-1, last paragraph, continuing to Pagc 2-3, is the first place whcre it is stated that only
areas A. B, C, and H have been selected for alternatives assessment and decision-making,
other portions of the 36-17N having been saeened out. It would be helpful if this
information were condensed and relocated to the Introduction.
The introduction is intended to present a bricf summary of the IRA decision for this site.
Dctailcd discussion of the site and the evaluation are more appropriate in later sections.
The shadcd areas of FJ8Ufe 2-2 need to be darkened or aosshatched to stand out dearly.
The figure has been revised.
On Pagc 2-5, Shell Oil Company is also a party to the Federal Facility Agrcement.
The text has been changed.
(3IIIDoGIo3P) (~IMII) (rD/JA/'IO)
-------
Comment 6:
Response:
Comment 7:
Response:
Comment 8:
Response:
Comment 9:
..-
Response:
,_J
.-' )."
.,~
WoocIward-Clyde:ConsuItants
The first paragraph .on Page ~2 discuss~s multi-layer caps to m;ft;",i~.e infiltration of
precipitation. Simulations using the EPA HELP model have shown that shole soil and
vegetative covers can effectively prevent the infiltration of precipitation to f . ~ .1dv....:r at
RMA. They are more cost-effective for the time period of an IRA.
Agre.ed. The type of cap would be determined during design. if a cap were t . )~ chosen for
an interim action at this site.
On Page ~2, the FFA criteria listed (4 bullets) are from 22.5 and 22.6. We recommend
adding a bullet for cost-effectiveness or stating (from 22.6) that the goal of the ISH'Cltftlalt
was to evaluate appropriate altematives and select the most cost-effective that attains the
objective of the IRA.
The bullet "Reasonableness of cost" has been changed to -Senefit in Terms of Cost. 8
Page ~2, last sentence, add 8. . . as required by paragraph 22.7 of the Federal Facility
Agreement.. .
The text has been changed.
The subsections of Section 4.2 do not match with the bullets listed as aiteria to be discussed.
Specifically, 4.2.2 has some further subsets which match the criteria and some that do not.
The intent may be to discuss contribution to the efficient performance of the final remedy,
as discussed in paragraph 22.5 of the FF A. If so, we recommend rewording to clarify.
The bullets have been revised to more clearly show that aiteria from the Federal Facility
Agreement are discussed within the context of the decision logic generally accepted by the
Organizations and the State in the June 7, 1989 subcommitte.e meeting.
Comment 10: In Section 4.2.2.1, second paragraph, the past disposal practice is better desaibed as ~uming.
(as on Page 2-3) rather than "incinerating".
Response:
The text has been changed.
Comment 11: On Page ~S, the conclusion of the paragraph discussing relative soil volumes would be
accurate only if the level of contamination and/or the final treatment were the same; that
is clearly not the case and we recommend deleting this paragraph.
Response:
Comment 12:
&_-
Response:
The Army agrees. Portions of the paragraph which can be misinterpreted have been
removed..
The CMP is mentioned on Page ~S in 4.2.2.2 and on Page 6-1 as the poS:.
for continued groundwater monitoring. We agree ~. :t is appropriate to
existing program can supply the data needed, to avoid ~lication of effon
noted in our general comment, careful selections of the location, indicator
frequency are needed. These are significant uncertainties (such as describ
paragraph of Page 4-4 and continuing to ~5) that can only be resolved with a J.
site-specific.
The Army wends to develop a site-specific monitoring program for the An ~plcx
Disposal Trenches. The CMP is mentioned u a mt.i"hllft;1I1It for CODductiDi aaual
.' sampling. IDdicator analytes and sampling frequency will be determined d~~ design.
Section 6.0 has been revised to clarify this.
meth!lfticftl
secifthis
1WeVer,1S
vre&, and
the last
CD more
~»JP) (-\*II) (fII/JA/9f1J
-------
......~ .'~4
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\Yoodwarct..CIydeCC;. L 11
_a-
Comment 13: In Section 6.0, the full suite of RMA aaaJytes should not be required to monitor for
cont~min:8nt migration over time. Shell recommends the seleCtion of appropriate target
aaaJytcs, basis mobility, already-known prcscnce or absence, ete:.
Response:
Section 6.0 has been revised to state that indicator anlaytes will be determined during the
design of this IRA.
Comment 14: The reference to 40 CFR part 50 on Page 8-2, first paragraph, desaibcs the contaiDed.
standards as neither applicable nor relevant and appropriate, but on Page 8-4; 1hiaID.~
paragraph, 40 CFR part 50.6 is considered as relevant and appropriate.
Response:
The Draft F'mal Decision Document was revised to reflect that the limitations contained in
40 CFR Part 50 are neither applicable nor relevant and appropriate to apply as specific
emissions limitations to this IRA but the particulate standards contained in SeCtion 50.6 are
relevant and appropriate to apply at the installation boundary.
I ~
...;
A.12
caz-C»JP) ~
-------
_~Ilts,
RRC\PONSE TO COMMENTS FROM SI-TF'T T OIL COMPANY
ON THE APPUCABLE OR RFT FVANr AND APPROP~RE~=~
FOR THE COMPI FY DISPOSAL TRENnIF~ IRA AND S I. '" ..~
With respect to the above-referenced documents, Shell Oil Company reserves the right to .nmeDt on how
any substantive RCRA standards, including land disposal restrictions, may apply to the Ii.As.
Response:
Shell's comment is noted. As Shell is aware, the IRA process provides for further.
opportUnity for review and comment.
. ,
A.13 .
-------
.. '. . ~ ..;~,~~~,~~ ~
COLORADO DEPARTMENT OF HEALTH
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... - .--...: II.
STATE OF COLOAAD~" AJ
4210 E~st 11th Avenue
Denver. Color~do 80220-3716
Phone ()03) 320-8333
Telelu:
(3031 322.9076 IM"n Buildinw/Der"'erl
/3031320-1529 !Ptumrwan Place/Den....,
(303) 248-7198IGrand lunCllon Rewional Ollice.
Roy Romer
COllemor
February 26, 1990
Thomas M. Vemon. M
hecuIive OirecIor
".' .!)~. '''''''.
Mr. Donald Campbell
Office of the Program Manager
Rocky Mountain Arsenal
Am'R.'1-R-f, Buildi~ 111
C~mmerce City, 00 80022-2180
Re: State Comments on the Proposed Decision Document for the Interim
Response Action at the Complex Disposal Trenches, Roc~' Mountain
Arsenal, Jan~' 1~90
. -
Dear Mr. Campbell:
Upon review of the above-referenced document, the State is especially
concerned with four key issues that remain unresolved. They include:
w
1.
The fact that the State believes that Site 36-17N is currently
insufficiently characterized. In addition to the selected
alternative of ground ~~ter monitoring, the State strongly supports a
program that tJill adequately characterize these trenches. Only after
the site is adequately ~haracterized can the fate of these trenches
be properl:\' determined. To facilitate this needed characterization~
the State will sutJnit the Central Study Area Data Gap Rectification
Proposal for additional characterization.
2.
The selection of monitoring as the "preferred alternative" for the
Arm.v trenches is based upon rationale that is inconsistent with that
presented by Shell in its Proposed Decision Document for Section 36
trenches. Such inconsistencies indicate that the decision-maki.na
criteria is being applied after decisions have alread.v been made, and
are not actually drivina the decision-makina process.
3.
The moni torina al ternati ve does not comprise an IRA. This selected
decision is inconsistent "'.ith the Primary ob.;ective for the Other
Contamination Sources IRA. as presented in the Final Technical
Program Plan, to "miti8'ate the threat of releases from selected "hot
spot" contamination sources." For this reason, the State, in its
Jan~ 2, 1990 letter, recommended that the issuance of the Decision
Document be postponed until sufficient information is gathered. and a
modified alternative assessment can be conducted. .
4.
It is currently unclear how the IRA process will revisit the selected"
decision if future site characterization indicates that the trenches
require i.JJJnediate remediation. An appropriate mechanism should be
-------
,..~. . ~~
-.:..;......
o.
~. Donald Campbell
PageZ
February 26. 1990
The State welcomes the opportunity to meet with the Ant:v to discuss these
issues in o~er to t'acil i tate their resolution.
If you have any questions. please feel free to call.
Sincere.ly /"
-, ° /
~) ,,(( /)'~
::ffr"~on °
RMA Project Manager
Hazardous Materials and
Waste Management Division
JE/cf
cc:
Michael Hope
Chris Hahn
Edwa~ McGrath
John Moscato
C<>nnally Mears
Bruce Ray
Tony Truschel
Major Lawrence
E. Rouse
'-
-------
.!~;.,:.~..
::=-,~
WooctlrJarO.~aab
RESPONSE TO CO~~O~~~~A~ O~i~~~
ON THE PROPOSED DECI I TR~CHES PONSE AcnQN
FOR THE COMPI FX DISPOSAL
General Commen~
~mment1:
The State agrees that groundwater monitoring is an e1fecbve method for gathering addWoaaJ
data needed at Site 36-17Ni however, it alone C3DDOt serve as a substit1,lte for adequate
trench characterization that has, to date, not been accomplisbed. The Army must, iD .NI~..
to IJti1;,n,g groundwater monitoriDg, thoroughly ~te all of the trench area. to
characterize them adequately.
J-
The F"mal Alternatives Assessment of Interim Response Actions for Other ContA"';".tion
So1,lJ'CCS Complex Disposal Trenches, January 1990, presents a very biased picture regarding
the degree of characterization completed at this site because it fails to present the percentage
of borings and exploratory trenches that were ac:tua1Jy completed in the trenches during the
Phase I and Phase n field investigation, and the field program conducted during the Spring
of 1989. State review of the Phase I and Phase n investigations reveal that only ODe of the
thirty Phase I borings completed was located within a trench, and, aa:ording to the Army,
only elevcn of the twenty Phase n borings targeted for the trenches were actually located
in the trenches; the remaining nine were completed in undisturbed soils. Since
contamination migration Crom the trenches into the groundwater would be predominately
downward (not lateral), borings placed on the perimeter or outside of the disposal trench
boundaries do not accurately characterize contamination beneath the trcnches.
In addition, no borings were completed in any trench or pit within Anomalies E and G, and
it is questionable whether Borings 3591 and 3592 in Anomaly F actually characterize the
disposal trenches in that anomaly (see forthcoming Central SAR Data Gap Rectification
Proposal). Therefore, the contaminA"t summary presented by the Army for these anomalies .
docs Agt represent actua.l contaminant distributions below the trenches. Additionally, the
majority of trenches in Anomalies A, B, and C, known to exist from Phase I geophysical data
and aerial photograph interpretations, havc not been investigated.
oW
Response:
FmaUy, the ~tiOD of the Spring of 1989 concentrated almost exclusively On ADomaJy
H. Of the twenty-five exploratory trenches completed hi the program, twenty-two were
completed withiD or immediately to the west of that anomaly. Only two trenchea wa'e
completed hi Anomaly A (both defining the same trench identified in the Phase n
invesbgation), and a single exploratory trench was completed in Anomaly F. This boring
encountered UDdisturbed soils. No trenches or boring. were completed in ADomalies B, C,
E, or G, which remain essentially uncharacterized.
Only after the lite has heeD sufficiently characterized can the fate of these trenches be
properly determined. To assist the Army in this CDdeavor, the State will submit a
chancterizatiOD plan for Site 36-17N as part of the State's Central Study Data Gap Plan.
1-
The Army maintA;"c that the Army Complc:z Disposal Trenches have been characterized
adequately for the purposes of this IRA. Additional data may be gathered, if determined
to be necessary by the Feasibility Study. However, adeqUate information On the IypeI of
wastea and cont....;"."t, exists to evaluate appropriate tinaJ response ac:tiOD aJternativea far
this site..
A-16
(8D 18 .U
-------
Woodward.Clyde Consultants
Tbe Phase I investigation was intended primarily to explore the undisturbed soils :
17N. In addition to the soil borings taken during...:. ~::..:-;; rI rnvestigatio
exploratory trenches were excavated, to better identify disposal trenches. Nin
samples were taken from the bottoms of the exploratory trenches during tho
investigation. These grab samples showed the major cont:lmin:lnts in these trer.
ICP metals, which are relatively immobile.
The Spring 1989 field investigation conccntrated on better defining the dispoSG :nches in
Anomalous Areas A and H because these trenches are in closest contact with S JDdwater.
Disposal trenches in Anomalous Areas B and C were characterized adequately in previous
m~gatiODS for the purposes of this IRA. Based on previous investigations, disposal
treucha in Anomalous Areas E and G are not considered for interim action, ezcept perhaps
additional monitoring, because they do not appear to 1) be in . direct contact with
groundwater; 2) contain Army agents or degradation products; or 3) be leaching
contaminants to groundwater.
. Ite 36-
.everal
" grab
.aseD
;; to be
The Army will consider the State's site characterization recommendations during the
Feasibility Study.
Comment 1:
SDecific Comments
'-
I ..
Response:
Comment 2:
D.1-11.0 Introduction - There appears to be an inconsistency with the Army's selection of
the monitoring alternative. It has been conclusively demonstrated by monitoring well data
that Anomalies A & H are .significantly- contributing to groundwater contamination (and
therefore should be considered "hot-spots.); yet a containment or removaJ/temporary storage
alternative was not selected, as was the case with the adjacent Shell trenches. Please explain
why Site 36-17N trenches that are contnDuting to the groundwater contamination will be
monitored, while the adjacent Shell trenches will utilize a containment option.
Shell's utilization of a containment system will reduce further migration of a confamin!!lnt
plume which includes dense nonaqueous phase liquids (DNAPI...s). Containment of this
plume now will provide a technical and cost benefit by limiting the spread of DNAPL
contamination before a final remedy can be implemented.
The Army Compa Disposal Trenches are located OYer an alluvial aquifer which is
coara",inAted from upgradient sources. While the Army trenches do appear to be adding
conta",in~~ts to the aquifer, containment of this contribution would have little effect on
overall groundwater quality in the area. Also, there do not appear to be contaminAnts
specific: to these trcnches that would influcnce the treatment system selection process Cor the
final cleanup of Section 36 groundwater. This is a fundamentally different situation than the
Shell Section 36 Trenches and c:annot be meaningfully compared with the She" Trenches.
Consequently, there does not appear to be a technical or cost benefit in contair. the Army
trenches at this time. However, the monitoring alternative choscn for this . includes
periodic reevaluation which could lead to additional action, including coD1ainu. if some
tt.l"hnicaJ or cost benefit can be mown.
D. 1-2 FillUJ'e 1-1. Decl$ion F10w Chart . Carification is neet~~~ as to how the won
process will retunl to consideration of remedial alternatives if fur .her sitc charact .won
indicates that the trenches require immediate remediation. The Fmal Decision D( .]Icnt
should recognize . procedure by whiCh a new or revised Decision DocumcDt we .Id be
implemented in thc event that additional site characterization indicat" su~ a n~
(~.) (-~) (f1.J1J'f90)
-------
Response:
Comment 3:
Response:
Comment 4:
,.-
t.i
.- . ~...
Woodward.CIyde-Consultant!
A procedure for reevaluation of this site during the life of the IRA is described in Section
6.0 of the revised Decision Document.
p. 2-4 F"mIre 2-2 - Location of Trenches in Site 36-17N - This figure appears to be generally
Jacking in information. Groundwater contamination data for the listed wells are not included,
and a number of groundwater monitoring well locations (such as 36090, 36U1, 36lS8, 36184,
and 36185) arc also omitted. F"JgUre 2-2, or additional figures, should contain such data.
F"zgure 2-3 has been added to show monitoring well locations. Appendix B was added to the
Draft F"mal Decision Document and includes soil and groundwater contJuninllltion data..
p. 2-5 2.0 Historv of the Comnle% Dist)osal Trenc:hes. 8th naram-aph - The text states that
1t]hc Complex Disposal Trenches in Anomalous Areas A and H are evaluated as being in
close, or direct contact with the groundwater during part of the year," suggesting that mI1x
these anomalies are contn'buting to groundwater contamination. Reccnt data from
downgradient wclls adjacent to the other anomalies refute this conclusion. In addition,
trenches in ill anomalies appear to meet one or aU of the aiteria enumerated in the Army's
F"maJ Task PIan Remediation of Other Contamination Sources, Volume I, 6/89, pg. 5-13
for determining which trenches would be included in the IRA. Thcsc criteria consist of the
following:
a. Currently or historically in contact with groundwater (Anomalies A & H);
b. Disposal sites for Army agent or degradation products (Anomalies B, C, G, and possibly
E and F); or
c. Impacting or potentially impacting the groundwater due to contaminant leaching.
For example, recent data from unconfmed Denvcr Well 36185 "located downgradicnt and
to the northeast of Anomaly G, indicate the prcscncc ot CODtaminlllnt compounds suspected
and confirmed to have been disposed ot within the anomaly" (Central Study Area Repon
[<::sARJ, Appendix CSA-F, Army Response to Shell Comment 102). This well is also located
downgradient of Anomaly E, indicating that trenches in the anomaly may also be contribUting
contaminants to groundwater. Similarly, contamination data from Well 36184 indicate that
trenches in Anomaly F as well as C may be contributing CODtJlllniftJlUon to groundwater aiDcc
both aDoma1iea are upgradienr of this wcll. (Anomaly C is recognized by the Army u a
possible primary source of groundwater contJlmin~tion, see p.2-1,2 of Proposed Decision
Document).
AecordingJy, the State contends that ill trenches in these Site 36-17N anomalies may be
contributing to groundwater CODtJllmmJltion, and hence require further characterization.
The detectioDS of diisopropylmethyl phosphonatc (DIMP) and dimethylmethyl phosphcmate
(DMMP) in wells 36184 and 36185 indicate also that upgradienr trenches were disposal sites
for Army agents and by-products, thereby satisfying the second criterion. Since well 36184
is downgradient oC both AnomaJy C and F, F cannot be excluded as a possible source of
Army degradation products. In addition, the Army concludes that Army agents or
degradation products were disposed oC in Anomalies B and C. Ground disturbances in
Anomaly B were evident in the 1948 aerial photographs, as were ground disturbances in
Anomaly F (Site 36-17 Phase I CAR, page 12), indicating that ADomalies B and F were used
concurrently as disposal sites. Because B and F wcre operated COntemporaneously and Army
agCDtS are bOWD to havc been disposed of ill Anomaly B trenches, it is possible that
~(~)(8"'f'JtI)
-------
Response:
Comment S:
''''
Response:
Comment 6:
Response:
Comment 7:
(3IIIW»JP)(
&-
......~...
WoocIward-CIyde.ConMtI,~.
Anomaly F was also used as an .army agent disposal site". If so it should have been included
in the IRA. .
The Army concurs with the State's review of the site history, but does nr . gree with the
Stat~'s inferences. It is true that Denver. monitoring wells (36184 anr J618S) located
do"'.~adient of the Army trenches do show groundwater contaminatic . Other Denver
Formation monitoring wells (36191 and 36192) installed during the 1989 :ld invesDgation
for this IRA show very little groundwater contamination. It is un ..ear whether the
groundwater contamination in the Denver Formation is coming from the trenches, or is
iDfiltrating from the alluvial aquifer. There are currently no Denver wells located upgradicDt
of the Complez Disposal Trenches to provide information for this determination. The Army .
believes that the data are inconclusive to determine whether the Army trenches are
contributing to groundwater cont"",i,,"tion in the Denver Formation. This question can be
addressed by instlllli"g upgradient wells during the implementation of the monitoring
alternative proposed for this IRA.
p. 4-3 4.2.1 . 1st parallraph . The Army's statement that "[t)he site does not appear to be
posing a significant risk to human health and the environment at this time" is contradicted
by the data available from the site. As the State pointed out in its January 2. 1990, 1cner
from Mr. Jeff Edson to Mr. Donald Campbell, a number of Army trenches are knowa to
be contributing significant concentrations of contaminants to the groundwater and soils.
Therefore, although there may not be direct human and biota receptors at this time, the
vadose soils and underlying groundwater are being exposed to continuing degradation.
Consequently, contrary to the Army's assertion, groundwater monitoring of the trenches
cannot be considered to be protective of the environment. Accordingly, these statements
should be modified or deleted from the text.
Please see the response to the EPA's Specific Comment No.1. In addition, the text has been
revised to state that "[ m )onitoring would allow continued tracking of contaminant movement,
thereby providing additional information on protection of human health and the
environment..
p. 4-S 4.2.2.1 fifth narall1'anh . The State concurs with the need for further characterization
in these areas. See General Comment # 1. As previously agreed by the Army at the
December 14, 1989, Army TreDches Subcommittee Meeting. the State should be involved
in the design of the Site 36-17N well monitoring program. The State requc.5tS that the
developmeDt of the program be initiated and approved by both parties prior to distributiOD
of thc implcmcDtatioD documcDt.
Development of the monitoring program can begin following fiDalizatiOD of this DccisiOD
Document. Opportunities will exist for input from thc Organizations and the State during
the development of the program.
p. 4-6 4' , ':
L The teu states that .. somce removal IRA alternative may Dot be COD 'tet h the
final rcmedy since source removal would preclude. final in situ treatml all :ive..
What sort of in situ treatment would be po5SJole in treDches that COD ;n ci. - .med
waste, unaploded ordnance and unburned ~~ciianes1
b. The Army's statement that (mJoDitoring is thc only alternative completely COftcict':Dt with
any final remedy" is inconsistcnt with thc ratioDaIc preseDtcd in Shell's Proposed
DccisioD Document for ScctiOD 36 TreDchcs. On pagc 3S of that documcDt, Shell states
A-19
-------
Response:
I.
L-
CommentS:
(~.,(
,,".;~"
...~:.,~~t~~-
" ""
. . -_._-- ._n_____" .
Woodt. ... d-~Qat5u1tants
its belief that 8this IRA will be consistent with and contribute to the efficient
performance oC the FmaJ Response ActioD by reduc:iag the spread oC CODtammAllts in
groundwater. . .8 Since the Army will not be reduc:iag the spread of CODtammAllts. its
selected alternative presumably will Dot be consistent with the fiDa1 remedy Cor the trench
area. The statemeDt, therefore, should be modified or deleted.
In addition, the Army has rejected the capping alternative in pan because it could 8generate
additional materials that may require remediatioD . . .8; yet, the capping alternative was
se1ected by Shell in part because 8it can reasonably be assumed to be consistent with-and
CODtribute to the efficient performance of the Fmal Respoase"AcDOII by reducinetbc.ap.-d-
of eontJlmn..tiOll during the IRA.. (page" 10, Shell Proposed Decision Dl\l"QDIent).
MODitoriDg/maiDtelWlce, on the other hand, was rejected by Shell because 8it did not meet
the objectives of the IRA., namely, the reduction of .lateral migration of dissoIYcd and
separate-phase (i.e., DNAPL) CODt:unillallts emanatiftg &om the Shell trenches. (page 6).
The inconsistencies of these approaches to the two sets of trenches should be ~Dcikd in
the respective texts.
a.
Some type of in situ solidification may be a feasible alternative, or a ncw in situ
technology may be developed in time for the ROD.
Monitoring is the alternative most consistent with the fiDa1 remedy Cor the Army
trenches because DO technical or cost bcDefit in performing any other action at this
time can be identified. Although other actioDS may be consisteDt with a final
remedy, monitoring is the only action comDletely consisteDt with any fiDal remedy
for this site. The text has bccn c:haaged to state that .[ m JonitoriDg is the alternative
most consistent with any fiDal remedy:
b.
The State appears to consider the Army and Shell trenches to be similar sites, therefore
requiring similar interim actioDS. The Army docs Dot agree with this interpretation. Because
these two sites are fundameDtally different, the Army has determined that the same interim
action is Dot appropriate for both sites, and thereCore there are no inconsistencies requiring
reconciliation. Shell has reached the same condusioD (see response to Shell', General
Comment No.1).
The Army disposal practice of burning treDch contents prior to burial appears to have been
effective in destroying most organic contamilllDts, and leaving primarily metal COllt.mmAqts
that are relatively immobile. Although the Army trenches do appear to be contributing to
grcnmdwater confamillition, the aquifer in this area is already COlttAmin~tcd from upgradient
sources. Therefore, there does not appear to be a technical or COSt benefit in performiDg
any action other than monitoring at this site at this time.
The Shell trenches do appear to be an acme source of groundwater CODtAminitiOD, iDcIuding
dense DODaqueoUS phase liquids (DNAPLa). Shell had determined, and the Army COIICUrS,
that there is a terhnica1 and COSt bene& in contaiDiDg this source at this time and ~
the spread of DNAPLa.
D. 5-1 5.0 ChrODOIMV of EYeDb . A number of eveDtI that warrant inclusion have been
OIDiacd. They iDdude:
October S, 1989 The State, EP A, and SheD conCUl' that a two-month I!!fteftsioa on the IRA
Dec:isioa Document is necessary to enable the Army to further revicw ~';Iti"g data, and
identify data gaps prior to the parties commenting on the Army's preferred alternative of
slurry wall and cap.
A-2Q
-------
Response:
L
....
Woodward. Clyde Consultants
November 14, 1989 Army announces that it is ~h:l"gi"g its preferred alternat:
wall and cap to that of monitoring, despite the faCt that the extension was F'
parties, in order for the Army to address site charaCterizatioD Deeds. Dot
selediOD of the preferred alternative.
'om slurry
:d, by the
.:baDge the
December 14, 1989 Army Letter Report is distribwed to the parties. The
the Army's coDclusioD that Site 36-17N is Dot curreDtly a "hot spo.
remediatiOD of the sources is therefore Dot Deces.sary.
,rt summaries
'ea, and that
January 2, 1990 State submits a positiOD letter to the Army stating that it strongly disagrees
with the coDclusioDS preseDted in the Army Letter Report.
The Army agrees with adding the OCtober S, 1989 2-moDth exteDSioD and the December 14,
1989 subcommittee meeting to the ChroDology of EveDts. The other items do Dot appear
to be appropriate for inclusioD in the ChroDology of EVCDts.
The December 14, 1989 Letter Report did Dot coDclude that the Army Complex Disposal
TreDches are Dot curreDtly a "hot spot." The Army ueDches are a source of groundwater
coDtaminatioD. However, the report concluded that there is DO technical or cost beDefit in
performing any action other than monitoring at this site at this time.
(2m-4»3P) (-~) (fDfJ'''''
-------
... .. -. ._.~~.~..:.&-~
CIydeC'onaulta-d$-
R~NSES TO COMMENTS FROM THE STATE OF COLORADO
ON APPUCABLE OR RFI FV ANT AND APPROPRIATE REOUIREMENTS
FOR THE RFM'FDIATION OF 01HER CONTAMINATION SOURCES - SEcnON 36 TRFN~
INTERIM RESPONSE AcnON
Comment 1:
Response:
Comment 2:
Response:
Comment 3:
Response:
Comment 4:
Response:
Page 8-2, Section 8.1.2.1: The section on air emissions states that the standards of 40 c.F.R.
Part SO, the National Primary and SctOndary Ambient Air Quality Standards, are considered
neither applicable nor relevant and appropriate to the IRA. The State has previously
CODUDcmed on the inappropriatCDcss of not considering the staDdards. as ARARs.. ~
standards are clearly ARARs because the area affected by the IRA is within an Air Quality
Conuol Region. In addition, the prOYisions of 40 CFR SO.6 are considered relevant and
appropriate later in the ARARs analysis (Section 8.4.2.1) making the above-specified
paragraph inconsistent with the Army's later analysis. rhe document should be revised to
include the National Primary and Secondary Ambient Air Quality Standards as ARARs.
The Draft F'mal Decision Document was revised to reflect that the specific limitations
contained in 40 CFR Part SO are neither applicable nor relevant and appropriate to apply
to a specific emissions source. The provisions of 40 CFR SO.6 are not applied to a specific
source.
Page 8-4, Section 8.4.2.1: The paragraph states that the provisions of 40 C.F.R. Section SO.6
are considered relevant and appropriate. However, Shell should also consider Colorado
Ambient Air Standards for Total Suspended Particulates (TSP), which are stricter than the
federal standards. The State has not yet adopted the federal PM10 standard, but rather
invokes the TSP standards. Therefore both the federal and State standards apply as ARARs.
Colorado's TSP standard is 150 ug/m' (24-maximum concentration) and 60 ug/mJ (annual
geometric mean). This standard is applicable at the property boundary and includes
background concentrations as well as source impacts.
The Draft Fmal Decision Document was revised in response to this ccmmeDt. It is noted
that the Army, not Shell, is responsible for the identification of ARARs.
Page 8-4, Section 8.4.2.3: In the section on general consttuc:tioD actMtics ARARs, Colorado
regulation No. 2, pcrtainiDg to odorous emissions should be included. For a predomm2fttly
residential or commercial area, the standard requires that odors must not be detected after
the emissions have been diluted with seven or more volumes of odor-free air.
The Draft F'mal Decision Document was revised in response [0 this C:O"''''CQt.
Page 8-9, Section 8.4.2.7: The document provides that for off-site disposal of haDrdous
material, the substantive provisions of 40 CFR part 262 (the document reads part 22), and
stricter corresponding State regulations found It 6 CCR 1007-3, part 262, are considered
rclcvant and appropriate. However, for any off-site disposal of hazardous wastes, the Army
must comply with all pertinent Colorado Hazardous Waste Management Act reg'l,ltltions.
both procedural and substantive, including 6 CCR 1007-3, part 262.
The Draft F'mal Decision Document was revised in response to this comment.
(~) (-\88) (fD/J'IfIj)
-------
APPENDIXB
SOIL AND GROUNDWATER. CONTAMINATION DATA
-------
Woodward. Clyde Consultants
APPENDIX B
SOIL AND GROUNDWATER CONTAMINATION DATA
This appendix contains groundwater and soil contamination data obtained during field investigations. The
groundwater monitoring well data were obtained from the RMA data base. The monitoring well data in Table
B-2 are presented in three groups:
.
Alluvial wells in Site 36-17S. to provide information on groundwater contamination upgradient
of the Complex Disposal Trenches.
Alluvial wells in Site 36-17N. to provide information on groundwater quality in the vicinity of
the Complex Disposal Trenches.
.
.
Denver Formation wells in Site 36-17N. to provide information on the Denver Formation
groundwater quality downgradient of the Complex Disposal Trenches. No Denver Formation
wells exiSt upgradient of the trenches.
The soil data are presented in Plate B-1. These data were obtained from the Contamination Ass~ccment Reports
(ESE 1988a and 1988b) and the 1989 field investigation for this IRA.
. ;
........
-------
Woodward-Clyde Consultants
TABLE 8-1
METIIODS OF ANALYSIS AND ANAL YI'ES
CHEMICAL NAME
ABBREVIATION
VOLATILE ORGANIC COMPOUNDS/GCMS
LJ
1,1-Dichloroethane
1,2-Dichloroethane
1,1,1- Trichloroethane
1,1,2- Trichloroethane
Benzene
Bicycloheptadiene
Carbon tetrachloride
Chlorobenzene
Chloroform
Dibromochloropropane
DicycJopentadiene
Dimethyldisulfide
Dimethyl ketone
Ethylbenzene
m-Xylene
Methylene chloride
Methylisobutyl ketone
0- and p-Xylene
Tetrachloroethylene
Toluene
Trans-1,2-dichloroethylene
Trichloroethylene
I1DCLE
12DCLE
I11TCE
l1ZI'CE
C6H6
BCHPD
CCLA
CLC6H5
CHCL3
DBCP
DCPD
DMDS
DMK
ETC6H5
13DMB
CH2CU
MIBK
XYLEN
TCLEE
MEC6H5
12DCE
TRCLE
HALOCARBONS/GCHALL
1,2-Dichloroethane
1,1,2- Trichloroethane
Carbon tetrachloride
Chloroform
Methylene chloride
Trichloroethene
Chlorobenzene
TetrachloroethCDC
12DCLE
11ZI'CE
CCL4
CHCL3
CH2CL2
TRCLE
CLC6H5
TCLEE
HALOCARBONS/GCCON
1,1- Dichlorocthanc
l,2-Dichlorocthanc
1,1-DichlorocthcDC
1,1,1- Trichloroethanc
1,1,2- Trichloroethane
Carbon tctrachloridc
Chlorobenzenc
Chloroform
Methylcne chloridc
Tetrachloroethenc
I1DCLE
12DCLE
I1DCE
111TCE
l1ZI'CE
CCL4
CL6H5
CHCL3
CH2a..2
TCLEE
-------
HALOCAR BONS /GCCON continued
Trans-1,2-dichloroethylene
Trichloroethcnc
AROMATICS/GCPJD
Benzenc
Etbylbcnzenc
m-Xylenc
0- and p-Xylcnc
Toluene
VOLA TILES /GCFID
Bicyclohcptadicnc
Woodward. Clyde Consultants
Tablc B-1
(continued)
12DCE
TRCLE
C6H6
ETC6HS
13DMB.
XYLEN
MEC6HS
BCHPD
SEMIVOLATILE ORGANIC COMPOUNDS/GCMS
oL.
1,4-0xathiane
2,2-bis(para-chlorophenyl)-
1,1-dichloroethanc
2,2-bis(Para -chlorophenyl)-
1,1-1-trichloroethanc
Aldrin
Atrazinc
Chlordanc
Chlorophcnylmcthyl sulfidc
Chlorophcnylmcthyl sulfonc
Chlorophcnylmethyl sulfoxide
Dibromochloropropanc
Dicyclopcntadicnc
Dicldrin
Diisopropylmcthyl phosphonate
Dimctbylmcthyl phosphonatc
Dithianc
Enwin
Hcxachlorocyclopcntadicnc
Isodrin
Malathion
Parathion
Supona
Vapona
~.J
ORGANOCHLORINE PESTICIDES/GCEC
2,2-bis(para-chlorophcnyl)-
1,1-dichloroethane
2,2-bis(para-chlorophcnyl)-
1,1,1-trichloroethane
Aldrin
Chlordanc
(~~21>311) (lbb-I.) (tD/I2/90).2
OXAT
PPDDE
PPDDT
ALDRN
ATZ
CLDAN
CPMS
CPMS02
CPMSO
DBCP
DCPD
DLDRN
DIMP
DMMP
DITH
ENDRN
HCPD/a.6CP
ISODR
mnIN
PRnIN
SUPONA
DDVP
PPDDE
PPDDT
ALDRN
-------
Woodward. Clyde Consultants
Table B-1
(continued)
ORGANOCHLORINE PESTICIDES/GCEC continued
Dieldrin DLDRN
Endrin ENDRN
Hexachlorocyclopentadiene CL6CP
Isodrin ISODR
ORGANOPHOSPHORUS COMPOUNDS/GCFPD
Diisopropylmethyl phosphonate DIMP
Dimethylmethyl phosphonate DMMP
ORGANOSULFUR COMPOUNDS IGCFPD
1,4-0xathiane OXAT
ChJorophenylmethyl sulfide CPMS
ChJorophenylmethyl sulfone CPMS02
ChJorophenylmethyl sulfoxide CMPSO
L . Dimethyldisulfide DMDS
ORGANOSULFUR COMPOUNDS/GCFPD (cont'd)
..... Dithiane DITH
Benzothiazole BTZ
'Ll AGENT PRODUcrS/HPLC
Chloroacetic Acid CLC2A
Thiodiglycol IDGCL
.. AGENTPRoDucrsnONCHROM
Fluoracetic Acid FC2A
Isopropylmethylpbospbonic Acid IMPA
Methylphosphonic: Acid MPA
METALSncp
Cadmium Cd
Chromium Cr
Copper Cu
,- Lead Pb
Zinc: ZD
NITROGEN PHOSPHORUS PESTICIDES/GCEC
Atrazme ATZ
Malathion MLTHN
Supona SUPONA
Vapon3 DDVP
Parathion PRTHN
-------
t.
r
TABLE B-2
ANAL YTES DETECTED ABOVE CERTIFIED REPORTING LIMIT
Alluvial Wells in Site 36-I7S
ICONTAMINANTI:/\36067.:::::J:()::36015)::136087:: I . . 36190 1 36S9O. 1..36591.. 1365931 SUMMARY.
I
Volatile Or2aDic Comoounds/OCMS
II DCLE 1(130) 1(130)
12DCLE 1(430) 1(430)
IIITCE
II2TCE 1(160) 1(160)
C6H6 4(220-20000) 2(6.4-41) 1(12) 7(6.4-20000)
BCHPD
CCU 1(1100) 1(1100)
CLC6H5 1(55) 1(1.1) 1 (460) 3(1.7-460)
CHCLJ 4(220-7100) 7(1.2-65) 1(8800) 3(71-2600) 15(1.2-8800)
DBCP
DCPD 1(3200) 1(3200)
DMDS
ETC6H5 1 (25) 1(25)
I3DMB 1(>90) 1(>90)
CH2CL2 3(2800-8100) 2(400-520) 5(400-81 (0)
MIBK 1(1200) 1(1200)
XYLEN 2(64-150) 2(64-150)
TCLEE 2(110-280) 2(110-280)
MEC6H5 3( 140-7(0) 3(140-700)
12DCE 1(120) - 1(120)
TRCLE 1(120) 5(1.0-1.7) 2(1.6-34) 8(1.0-120)
DMK 1 (29000) 1 (29000)
-------
!
r
ICONTAMINANTI:,):'36061"TSl::::::::3607S :.. . I
H.loc.rbons/OCHALL
CCLA
CHCLJ
CH2CL2
TRCLE
CLC6HS
Arom.tics/OCPID
C6H6
ETC6HS
I3DMB
XYLEN
MEC6HS
Semivol.tile On~.nic Comoounds/OCMS
OXAT
PPDDE
PPDDT
ALDRN
ATZ
CLDAN
CPMS
CPMSO
CPMS02
DBCP
DCPD
(1ocn~1o-JtI '''''1>-11.2
TABLE B-2
(Continued)
t ..
t
Alluvial Wells in Site 36-17S
36081 I 36190 I. 36590 .
3(21-45)
3(>300)
2(29- 35)
1 (230)
1(41)
1(3.9)
1(56)
1(2.1)
36591 ...36593.. .::.ISUMMARY.
1(4300) 1 (I (0) 3(100-4300)
1(4300) 1 (290) 3(47-4300)
1(1700) 1(15) 3(3.9-1100)
1(99) 1(37) 3(31-99)
1(19) 1(19)
1(8.4)
1(25)
1(23)
1(670)
1(280)
1(280)
'1(8.4)
1(25)
2(2.7-23)
1(670)
1(23)
1 (260)
1(9.2)
1(23)
1 (260)
4(9.2-45)
3(>300)
-------
~
~
~.
t..
r
TABLE B-2
(Continued)
Alluvial Wells in Site 36-17S
ICONTAMINANTI:\::3606tti::!::::}J6015:: '.: '" . 36087, I., 36190 I. 36590 ,I., '.36591 ' I:. ,36593: I SUMMARY , "
Semivolatile OrR8nic ComDOUDds/GCMS (cont"d)
DLDRN
DlMP
DMMP
DITH
ENDRN
CL6CP
(SODR
MLTHN
PRTHN
SUPONA
DDVP
3(>200)
3(>200)
1(13)
1(13)
Or2snochlorine Pesticides/GCEC
PPDDE 2(0.68-0.74)
PPDDT 2(2.2-2.7)
ALDRN 2(0.70-0.78)
CLDAN 1(13)
DLDRN 2(1.7-1.9)
ENDRN 2(1.9-2.0)
CL6CP 2(0.93-1.9)
(SODR 2(5.~5.8)
3(1.0->10) 1(0.74) 1(0.65) 5(0.65->10)
3(0.86-3.4) 1(0.15) 1(0.77) 7(0.15-3.4)
3(0.76-1. 8) 1(0.17) 1(0.96) 7(0. 17- I. 8)
2(12-17) 1(59) 4(12-59)
1(0.093) 1(2.4) 1(0.19) 1(4.5) 6(0.093-4.5)
2(2.2-3.0) 1(0.19) 1(0.71) 6(0.19-3.0)
1(3.3) 1(2.4) 1(0.87) 1(3.1) 6(0.87-3.3)
1(0.22) 2(2.6-3.3) 1(0.081) 1(0.45) 7(0.081-5.8)
Or21noPOOsphorous Compounds/OCFPD
DIMP 1(550) 1(0.47)
DMMP 1(1600)
1(2.8)
2(11-2200)
3(1000-1200)
3( 1200-2(00)
1(1.1)
1(1100)
1(47)
1(750)
1(12)
8(0.47- 12(0)
9(11-2200)
(]002~1)-J91 (1Nb-21.)
I
-------
r: ,'-
~ '
l
.
TABLE B-2
(Continued)
Alluvial Wells in Site 36-17S
ICONTAMINANTl::\#36067:j:!\:\::3607S ",.. : 1 ' '36087', I, ,: 36190 I" 36590 ,I
36591 ,) 36S93 ISUMMARY ,..
OfJ~anosulfur Compounds/OCFPD
OXAT 3(5.6-8.6) 3(5.6-8.6)
BTZ 3(16-34) 3(16-34)
CPMS 1(6.6) 1(6.6)
CPMSO 1(36) 3(22-41) 4(22-41)
CPMS02 3(16-69) 3(16-69)
DMDS 3(8.5-950) 3(8.5-950)
DIT" 2(14-19) 2(14-19)
Dibromoch)oropropane/GCECD
1(2300) 3(530-1200) 1(63) 1 (900) 1(13) 7(13-2300)
Allent ProductslHPLC
CLC2A
TDGCL
Allent productsnONCHROM
FC2A
IMPA
MPA
ICP METALS
Cd
Cr 1(9.7) 2(50-67) 3(9.7-67)
Cu 1(9.5) 1(27) 2(9.5-27)
Pb
Zn 2(25-29) 3(27-150) 5(25-150)
-------
CONTAMINANT
Arsenicl AA
Mercuryl AA
... . ]/CIVIC ..
.:;)::r uu,~ .:;
- II: Not aD8lyzed or Dot detected above CRL
number of indications i. followed by (nnge ugll)
(2002~)t1 (1tA-2MI
c
,
.
TABLE B-2
(Continued)
Alluvial Wells in Site 36-17S
.36087 . 36190 36S90
3(16-55)
. 36S91 .
SUMMARY...
-------
~ . ~'" r'
; I.
'-.. ~_.- '- .
-
ICONTAMINANTIi',=:36080:L.:: 36084 .:. . I
Volatile Or2anic Compounds/GCMS
II DCLE
12DCLE
IIITCE
112TCE
C6H6
OCHPD
CClA
CLC6HS
CHCLJ
DOCP
DCPD
DMDS
ETC6HS
I3DMB
CH2CL2
MIBK
XYLEN
TCLEE
MEC6HS
12DCE
TRCLE
DMK
1(4.9)
1(1.1)
1(0.78)
I(S.5)
1(5.4)
1(20)
C2002~o-)t) (l1li1>-3).1
1(19)
1(21)
1(1.7)
1(5.3)
1(38)
1(7.6)
1(7S)
1(>83)
TABLE B-2
(Continued)
Alluvial Wells in Site 36-17N
. 36085.
. 36088
1(79)
1(170)
1 (940)
I
36180
2(130-180)
1(230)
1(1700)
1(26)
2(110-270)
36187
1...36188
1(16)
1(1.2)
1(2.4)
I
36189
2(19-21)
2(3.8-4.0)
2(2.2-2.S)
2(1.8-8.6)
2(97-100)
I SUMMARY I
8(4.9-180)
4(1.1-21)
3(0.78-230)
2(S.3-1700)
5(2.2-38)
1(170)
2(7.2-7.6)
4(5.4-75)
7(2.4-270)
-------
CONT AMINANTi:::36080::H :)'" 36084:::
Halocarbons/GCHALL
12DCLE
II2TCE
CLC6H5
CHCU
TCLEE
TRCLE
Halocarbons/OCCON
12DCLE
IIITCE
II2TCE
CCIA
CLC6H5
CHCLJ
TCLEE
12DCE
TRCLE
4(12-22)
3(12-36)
3(2.5-4.4)
3(28-44)
4(6.1-8.3)
3(61-78)
4(86-1100)
Aromatics/GCPID
C6H6
ETC6H5
13DMB
XYLEN
MEC6H5
3(8.5-15)
C200J-f2o-J.) (I
.,
TABLE B-2
(Continued)
~
1....
.,.. -,
(
Alluvial Wells in Site 36-11N
..... 36085 . .
1(1.1)
1(0.68)
36088
36180
2(130-140)
2(2.3-2.6)
1(350)
2(5.5-10)
1(4.5)
1(100)
2( 110-210)
1(1.1)
2(4.1-4.6)
1(3.8)
2(2.2-1400)
2(5.8-18)
2(4.1-6.0)
3(2.1-2.4)
2(12-110)
4(11-20)
2(2.4-6.3)
1(5.0)
2(6.5-14)
2(>11-110)
. 36187 ...
q36188>
36189....
SUMMARY
2(130-140)
2(2.3-2.6) .
1 (350)
2(5.5-10)
1(4.5)
1(100)
1(1.1-210)
4(1.1-36)
2(4.1-4.6)
1(3.8)
5(2.2-1400)
5(5.8-44)
6(4.1-8.3)
6(2.1-18)
1(0.68-1100)
1(8.5-20)
2(2.4-6.3)
1(5.0)
2(6.5-14)
-------
CONTAMINANT .
Volatiles/GCFID
BCHPD
.... 36084 ...
.:.:)/:::.' ::\~::'
Semivol.tile Onr.nic ComPOUnds/GCMS
OXAT 3(45-57)
PPDDE
PPDDT
ALDRN
ATZ
CLDAN
CPMS
CPMSO
CPMS02
DBCP
DCPD
DLDRN
DIMP
DMMP
DITH
ENDRN
CL6CP
ISO DR
MLTHN
PRTHN
SUPONA
DDVP
(2002~o-)91 (11)11>-2).'
3(>200-6000)
2(>100-350)
TABLE B-2
(Continued)
t.
,.
~
Alluvial Wells in Site 36-17N
. 36085
36088
36180
1(2.3)
1(160)
1(>200)
1(>100)
36187 ..
... 36188 .
1(59)
1(>200)
, .
36189 .
2(120-130)
2(>200)
2(> 1 00)
. SUMMARY
1(2.3)
7(45-130)
7(>200-6000)
-------
,.. -
I.
TABLE B-2
(Continued)
CONTAMINANT: .:\.36080./. ... ... 36084 . 36187 :. 36189 . SUMMARY
::.:~x:::':~{ " ::=
OfJ~8nochlorine Pesticides/GCEC
PPDDE 1(6.4) 1(0.75) 1(0.17) 1(0.34) 2(0.23-0.67) 6(0.23-6.4)
PPDDT 1(19) 3(0.13-1.6) 1(0.47) 1(0.34) 6(0.13-19)
ALDRN 1(3.4) 1(8.2) 2(0.75-6.9) 4(0.75-8.2)
CLDAN 1(9.1) 2(9.9-120) 3(9.7-120)
DLDRN 1(3.7) 2(0.51-6,61) 2(0.34-6.79) 1(0.39) 2(0.23-2.1) 1(0.056) 1(0.78) 2(0.11-6.12) 12(0.056-3.7)
ENDRN 1(17) 1(0.33) 2(0.17-6.32) 1(0.098) 3(0.16-6.50) 2(0.085-6.11) 10(0.085-17)
CL6CP 1(0.15) 1(0.096) 2(0.066-0.071) 4(0.066-0.15)
ISODR 1 (20) 2(0.074-3.2) 1(0.16) 1(0.83) 2(0.76-0.94) 1(0.063) 1(0.75) 2(0.18-0.19) 11(0.063-20)
Nitro2en PhosPhorous Pesticides/OCEC
. ATZ 1(15) 1(25) 2(15-25)
MLTHN 1(1.2) 1(14) 2(1.2-14)
SUPONA 1(0.97) 1(0.97)
DDVP 1(0.86) 1(0.86)
OrRanophosphorous Comoounds/OCPPD
DIMP 1(8600) 4( 10-140(0) 2(90-170) 1(95) 4(2600-7800) 1(1.9) 1(27000) 2(5400-6200) 16(1.9-27000)
DMMP 2(1.8-18) 1(7.8) 1(30) 4(1.8-30)
OrR8nosuifUr Comoounds/GCFPD
OXAT 4(40-68) 1(11) 3(130-170) 1(24) 1(94) 2(220) 12(11-220)
BTZ 1(5.3) 1(23) 2(5.3-23)
CPMS 1(11) 3(13-19) 4(11-19)
CPMSO 2(15-48) 1(18) 3(15-48)
(1002 -420- 3t
-------
,'. -.
~
I
. .
TABLE B-2
(Continued)
. ..36080.
CONTAMINANT ... .. ",. 36187 . 36189 SUMMARY
.::(/: ?:::
Or~8nosulfur Comoounds/GCFPD (cont'd)
CPMS02 1(> 100) 1(14) 1(160) 2(31-33) 5(14-160)
DMDS
DITH 4(>22-490) 1(140) 3(1700-2100) 1 (250) 1(690) 2( 1800) 12(>22-2100)
Dibromochlol'ODJ'OIJ8ne/GCECD
1(190) 2(0.20-8.5) 3(0.20-190)
A2cnt ProductslHPLC
CLC2A
TDGCL
A2cnt productsnONCHROM
FC2A
IMP A
MPA
ICP METALS
Cd 1 (16) 1(16)
Cr 1(59) 1 (82) 2(59-82)
Cu 1(120) 2(11-31) 3(11-120)
Pb
Zn 1 (35) 3(23-42) 1(27) 3(22-280) 1(24) 9(22-280)
-------
I CONTAMINANT 1:::)<:36080\': .1: }.36084U..
Arsenic
3(>So-I30)
Mercury
- - Not aR8tyzed or not detected above CRL
Dumber of indicatiODl i. followed by (nng8 ugn)
(200'J -410-]
1.11
('-. .
TABLE B-2
(Continued)
Alluvial Wells in Site 36-17N
360BS I . 36088. I 36180
1 (>SO)
2(44-67)
36187 . 1 .36188 .:...1- . 36189 .1 SUMMARY I
2(48) 1(78) 2(71-73) 11(44-130)
-------
C. ~
~
L
TABLE B-2
(Continued)
Denver Wells in Site 36-17N
CONTAMINANT . :3612[:(.. .:.36154 " . 36158 36184 . 36191. SUMMARY
Volatile Or2anic ComPOUnds/GCMS
II DClE 1(44) 1(44)
12DCLE 1(43) 1(43)
III TCE
112TCE
C6H6 1(360) 1(360)
BCHPD
CClA 1(1.8) 1(1.8)
CLC6H5
CHCLJ 1(4900) 1 (90) 2(90-4900)
DBCP
DCPD
DMDS
ETC6HS
13DMB
CH2CL2 1(9300) 1(120) 2( 120-93(0)
MIBK
XYLEN
TCLEE 1(2900) 1(320) 2(320-2900)
MEC6H5
12DCE
TRCLE 1(500) 1(170) 1(27) 3(27-500)
II DCE 1(1900) 1(67) 2(67-1900)
Haloc8rbons/GCHALL
12DClE 2(2.8-7.0) 2(2.8-70)
CClA 1(3.3) 1(3.3)
-------
CONTAMINANT/:3612L
"aloearOOns/GCCON
CHCU
CLC6H5
IIITCE
IIDCE
II DCLE
12DCE
CCU
CH2CL2
TCLEE
TRCLE
12DCLE
Aromatics/GCPID
C6H6
1(1.6)
:36122 .:
Semivolatile Ortanic Comoouncls/GCMS
OXAT
PPDDE
PPDDT
ALDRN
ATZ
CLDAN
CPMS
CPMSO
CPMS02
DBCP
(200] ~2C)-)91
u
(
TABLE B-2
(Con.inued)
1(4.5)
1(24)
36185
36191 . .
.. 36192
SUMMARY
1(6700) 2(4.5-6700)
1(24)
1 (180) 1(56) 2(56-180) .
1 (2000) 1(130) 2( 130- 2000)
1 (51) 1(51)
1(8.8) 1(8.8)
1(140) 1(140)
1(17000) 1(17000)
1(15) 1(5700) 2(15-5700)
1 (880) 1 (280) 2(280-880)
1(11) 1(11)
1(25)
1(210)
-------
CONT AMINAN"r:\/: 36121i{(?
Semivolalile Or21nic ComPOUnds/GCMS (cont'd)
DCPD
DLDRN
DlMP
DMMP
DITH
ENDRN
CL6CP
ISODR
MLTHN
PRTHN
SUPONA
DDVP
Or2anochlorine Pesticides/GCEC
PPDDE
PPDDT
ALDRN
CLDAN
DLDRN
ENDRN
CL6CP
ISODR
(1002 -4Jo-)91(lbI1o-2).14
1(0.098)
TABLE B-2
(Continued)
r .,..
..
~
Denver Wells in Site 36-17N
;: 36154 - - 36158 36184 --
1(0.12)
1(0.30)
1(0.074)
1(0.30)
1(2.0)
1(4.4)
1(0.098)
2(0.12-0.19)
1(0.19)
1(0.44)
- 36185 --
1(0.050)
.. 36191 ;-:
SUMMARY
3(0.074-0.12)
2(0.30)
1(2.0)
1(4.4)
2(0.050-0.098)
2(0.12-0.19)
1(0.19)
1(0.44)
. .
-------
CONTAMINANT ::>36i2h// ..)::;:36122
NitroRen Phosphorous Pesticides/GCEC
ATZ
PRTHN
SUPONA
OrR8nODhosphorous Comoounds/GCFPD
DIMP
DMMP
OrR8nosuifur Comoouncls/GCFPD
OXAT
BTZ
CPMS
CPMSO
CPMS02
DMDS
DITH
DibromochlorODf0D8ne/GCECD
ARent ProductslHPLC
CLC2A
TOOCL
(1002-421)-)9)
).U
TABLE B-2
(Continued)
.
I.
~
1(93)
1(1.3)
.. 36185
1(1.2)
2(2100-3200) 2(180-200)
2(6.S- 31)
1(1.1)
< 36191.i
1(0.93)
SUMMARY
1(93)
1(1.3)
1(1.2) .
4(180-3200)
2(6.S- 31)
..
-------
.
.
TABLE B-2
(Continued)
.. .
L.
~
Denver Wells in Site 36-17N
ICONTAMINANT!:}(:3612t::::I):i36122+0l ..36154 I. 36158 . I 36184
ARent ProductsllONCHROM
FC2A
IMPA
MPA
ICP METALS
Cd
Cr
Cu
Pb
Zn
1(26)
1 (39)
2(28-68)
1(34)
Arsenic
Mercury
Cyaniderrechnicon
1(13)
- - Not aDllyzed or not detected above CRL
number of indications is followed by (nnge ugll)
(1ocn~o-J9) (dA-2). If
2(23-80)
2(6.7)
.
. 36185 'I .36191.. t ... .36192 ... I SUMMARY I
2(420-500)
1(160)
1(26)
1 (39)
7(23-500)
2(6.7)
-------
r
i
.
DEPARTMENT OF THE ARMY
PROGRAM MANAGER FOR ROCKY MOUNTAIN ARSENAL
COMMEI'CI: OTY. COI.~ 80022.2' 80
March 29, 1990
cG"""""'",-
(~~
'\ ~
.~ "
~"'~
"'LY TO
UUIITIO. M:
Interim Response Division
r ~.~ ~. ~~ ' '. / :-: j .
Mr. Connally Mears
U.S. Environmental Protection Agency
Region VllI
One Denver Place
Suite 801
999-18th Street
Denver, Colorado 80202-2405
.. .,
" :.. .. J
J - -". .
~ ~ -...J
~ \"'" : 'j
." . .... ..:
- :41''''''' , . ~ J t.-."
Dear Mr. Mears:
Enclosed for your review are the Draft Final Decision Documents for the Army
Complex Disposal Trenches and Shell Section 36 Trenches Interim Response Actions
(IRAs) at Rocky Mountain Arsenal. These documents are being issued in accordance
with paragraph 22.9 of the Federal Facility Agreement (FF A).
. .
Following consideration of all comments received during the public comment
period from January 27, 1990 through February 26, 1990, the Army has revised the
Decision Documents for the Army Complex Disposal Trenches and Shell Section 36
Trenches where appropriate. .
In accordance with paragraph 22.10 of the FF~ Organizations with standing to
invoke the dispute resolution process should advise me and my counsel in writing within
twenty days of issuance of these documents, if they wish to invoke the procedures for
dispute resolution.
In accordance with paragraph 22.11 of the FF~ after the close of the period for
inyoking Dispute Resolution, if Dispute Resolution is not invoked, or after completion
of Dispution Resolution, if invoked, the Army shall issue a final IRA Decision
Document to the other Organizations and Department of Interior. Unless Dispute
Resolution is invoked within the twenty day dispute period, the Army will consider the
decisions in the Draft Final Decision Documents the final decision for the Army
------- |