PB95-964609
                            EPA/ROD/R10-95/114
                            July 1995
EPA  Superfund
       Record of Decision:
       Hanford 200-Area (USDOE)
       OU 200-ZP-l, Benton County, WA
       5/24/95

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                DECLARATION OF THE RECORD OF DECISION
SITE NAME AND LOCATION

USDOE Hanford 200 Area
Hanford Site
Benton County, Washington

STATEMENT OF BASIS AND PURPOSE

This decision document presents the selected interim remedial measure (IRM)  for the
USDOE Hanford 200-ZP-l operable unit, 200 Area, Hanford Site, Benton County,
Washington.  The IRM was chosen in accordance with the Comprehensive Environmental
Response, Compensation, and Liability Act of 1980 (CERCLA), as amended by the
Superfund Amendments and Reauihorization Act of 1986 (SARA), the Hanford Federal
Facility Agreement and Consent Order (also known as the Tri-Party Agreement or TPA), and
to the extent practicable, the National Oil and Hazardous Substances Pollution Contingency
Plan (NCP).  This decision is based on the Administrative Record for this site.

The State of Washington concurs with the selected remedy.

ASSESSMENT OF THE SITE

Actual or threatened releases of hazardous substances from this site, if not addressed by
implementing the response action selected in this interim Record of Decision (ROD), may
present a current or potential threat to the public health, welfare,  or the environment.

DESCRIPTION OF THE SELECTED REMEDY

The selected remedy uses  groundwater pump and treat and is intended to minimize further
migration of carbon tetrachloride, chloroform, and trichloroethylene (TCE) in the
groundwater of the 200 West Area.   To do this, the IRM is designed to stabilize and reduce
contaminant mass in the high concentration portion of the plume. The high concentration
portion of the plume corresponds to the area within the 2000 - 3000 parts per billion (ppb)
contour of carbon tetrachloride.  A more detailed discussion of conceptual design for the
IRM is contained in the Engineering  Evaluation/Conceptual Plan for the 200-ZP-l Operable
 Unit Interim Remedial Measure which is available in the Administrative Record (AR). This
action will occur in three  phases. Pilot scale operations are underway to determine the
effectiveness of the system. Initial results indicate that expansion of the system is warranted.
The degree of expansion will be based  on the amount of groundwater extraction and treated
water reinjection that is deemed feasible and necessary to  contain the high concentration area.
It is estimated that the initial expansion (Phase IT) will  upgrade the total pump and treat

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capacity to about 570 liters per minute (150 gallons per minute).  Up to three new wells may
need to be installed to support scale-up to 570 liters per minute (150 gallons per minute).
This system will be operated to continue gathering data on the effects of pump and treat on
plume containment and mass removal.  A final expansion (Phase HI) will be initiated in fiscal
year 1998, resulting in a pumping rate in the range of 570 to  1900 liters per minute (150 to
500 gallons per minute) in order to meet the objectives of mass removal and plume
containment.  Initial estimates show that up to 19 new wells may need to be installed to
support full-scale pumping operations. Pump-and-treat operations would continue until
selection of a final remedy,  or until such time that DOE demonstrates to EPA that no further
interim pump and treat operations would be required to protect human health and  the
environment.  The actual time required will be determined as  the interim action progresses.
It is anticipated that this action, if successful,  would continue  until at least the year 2000.

Monitoring will be performed throughout the interim action activities.  Additional
information will be collected to support  the expansion on  an as-needed basis.

The treatment train for the Phase n (treatment system upgraded to 570 liters per minute (150
gallons per minute)) and Phase m (treatment  system upgraded up to 1,900 liters per
minute(500 gallons per minute)) of this interim remedial measure is air  stripping with vapor
phase activated carbon used to capture stripped contaminants.  The treated groundwater will
be reinjected  into the aquifer through wells located within the area of contamination.

STATUTORY DETERMINATIONS

This interim action is protective of human health and the environment in the short term and
is intended to provide adequate protection until a final ROD is signed, complies with federal
and state applicable or relevant and appropriate requirements  for the three primary
contaminants identified in this limited scope action, and is cost effective.  Although this
interim action is not intended to address fully the statutory mandate for permanence and
treatment to the maximum extent practicable, this interim action does utilize treatment and
thus is in furtherance of that statutory mandate.  This action does not constitute the final
remedy for the 200-ZP-l Operable Unit.  However, the statutory preference for remedies
that employ treatment that reduces  toxicity, mobility, or volume as a principal element is
addressed in  this remedy.  Subsequent actions are planned to  address fully the threats posed
by  this operable unit. Because this is an interim action ROD, review of this operable unit
and of this remedy will be ongoing as the three parties continue to develop and evaluate final
remedial alternatives for the 200-ZP-l Operable Unit.

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Signature sheet for the Record of Decision for the USDOE Hanford 200-ZP-l Operable Unit
Interim Remedial Measure between the United States Department of Energy and the United
States Environmental Protection Agency, with concurrence by the Washington State
Department of Ecology.
John D. WagonerX             \J                                              Date
Manager, Ricraano Operations
United States Department of Energy

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Signature sheet for the Record of Decision for the USDOE Hanford 200 ZP-1 Operable Unit,
200 Area NPL Site Interim Remedial Measure between the United States Department of
Energy and the United States Environmental Protection Agency, with concurrence by the
Washington State Department of Ecology.
Chuck Clarke                                                                 Date
Regional Administrator, Region 10
United States Environmental Protection Agency

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Signature sheet for the Record of Decision for the USDOE Hanford 200-ZP-l Operable Unit
200 NPL Site Interim Remedial Measure between the United States Department of Energy
and the United States Environmental Protection Agency, with concurrence by the Washington
State Department of Ecology.
  ichael Wilson                                                               Date
Program Manager, Nuclear and Mixed Waste Program
Washington State Department of Ecology

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                       TABLE OF CONTENTS
DECLARATION OF THE RECORD OF DECISION
DECISION SUMMARY	  1
     INTRODUCTION	  1
     SITE NAME, LOCATION, AND DESCRIPTION	  1
     SITE HISTORY AND ENFORCEMENT ACTIONS	  1
     HIGHLIGHTS OF COMMUNITY PARTICIPATION	  3
     SCOPE AND ROLE OF RESPONSE ACTION WITHIN SITE STRATEGY  ...  6
     SITE CHARACTERISTICS  	  7
     SUMMARY OF SITE RISKS	11
     REMEDIAL ACTION OBJECTIVES  	11
     DESCRIPTION OF ALTERNATIVES	12
     SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES	14
     SELECTED REMEDY	16
     STATUTORY DETERMINATIONS	17
     DOCUMENTATION OF SIGNIFICANT CHANGES 	21

     RESPONSIVENESS SUMMARY	.22
                               VI

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                              DECISION SUMMARY
INTRODUCTION
The U.S. Department of Energy's Hanford Site was listed on the National Priorities List
(NPL) in July 1989 under authorities granted by the Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA) of 1980, as amended by the Superfund
Amendments and Reauthorization Act (SARA) of 1986. The Hanford Site was divided and
listed as four NPL Sites:  the 1100 Area, the 200 Area, the 300 Area, and the 100 Area.

This action is being taken as an interim action  and is expected to become part of a final
remedy selection for the 200-ZP-l operable unit which is part of the 200  Area NPL site.

I. SITE NAME, LOCATION, AND DESCRIPTION

The Hanford Site is a 1,450-square kilometers (560 square miles) Federal facility located
along the Columbia River in southeastern Washington, situated north and west of the cities of
Richland, Kennewick, and Pasco, an area commonly known as the Tri-Cities (Figure 1).
The 200  Area NPL Site is located in the central portion of the Hanford Site, and covers less
than 40-square kilometers (15 square miles). The 200-ZP-l operable unit is located in the
200 West Area of the 200 Area NPL site.   Contamination to the groundwater in the 200-ZP-
1 Area resulted from historic discharges from the Plutonium Finishing Plant.

The land surrounding the Hanford Site is used primarily for agriculture and livestock
grazing.  The major population center near the Hanford Site is the Tri-Cities, with a
combined population of approximately 100,000.

The land is semi-arid with a sparse covering of cold desert shrubs and drought resistant
grasses.  Forty percent of the area's annual six and one quarter inches of rain occurs between
November  and January. In part due to the semi-arid conditions, no wetlands are contained
within the boundary of 200-ZP-l.

The Columbia River is located approximately ten miles east of the 200 West Area.  The 200
West Area is not within the 100 year floodplain of the river.

H. SITE HISTORY AND ENFORCEMENT ACTIONS

The Hanford Site was established during World War TJ as part of the Army's "Manhattan
Project"  to produce plutonium for nuclear  weapons. Hanford Site operations began in 1943,
and DOE facilities are  located throughout the  Site and the City of Richland.  The land
occupied by the Hanford  Site was ceded to the United States by various Native American
tribes in treaties signed in 1855.  The treaties  reserve certain rights to fisheries and to the use
of open and unclaimed land. Certain portions of the Site are known to have cultural


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I.-i«urc 1-  Location of Hunford Site and 200 West Area.

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significance and may be eligible for listing in the National Register of Historical Places.

In 1988, the Hanford Site was scored using EPA's Hazard Ranking System.  As a result of
the scoring, the Hanford Site was added to the NPL in July  1989 as four sites (the 1100
Area, the 200 Area, the 300 Area, and the 100 Area). Each of these areas was further
divided into operable units (a grouping of individual waste units based primarily on
geographic area and common waste sources).

In anticipation of the NPL listing, DOE, EPA, and Ecology entered into a Federal Facility
Agreement in May 1989. This agreement established a procedural framework and schedule
for developing, implementing, and monitoring remedial response actions at the Hanford Site.
The agreement also addresses Resource Conservation and Recovery Act (RCRA) compliance
and permitting.

The 200-ZP-l operable unit is one of two groundwater operable units located in the 200
West Area and is shown in figure 2.  Contamination in the 200-ZP-l operable unit resulted
from historic discharges  to three primary liquid waste disposal sites.  These sites are the 216-
Z-9 trench, the 216-Z-1A tile field, and the 216-Z-18 crib.  The predominant contaminants in
the waste stream were carbon tetrachloride and plutonium.  Monitoring data indicates that
almost all of the plutonium has bound to the soil column and little has reached the
groundwater.  It is estimated that 600 to 1,000 metric tons of carbon tetrachloride was
discharged to the soil from 1955 to 1973.

In 1991 a CERCLA removal action was initiated utilizing vapor extraction systems to (1)
remove the carbon tetrachloride from the vadose zone; and  (2) prevent further migration to
the groundwater.  To date, over 45,360 kilograms (100',000 pounds) of carbon tetrachloride
have been removed from the soil column. It is anticipated that the removal action and this
groundwater interim remedial action will continue until,at least the year 2000.

This Interim Remedial Measure addresses the carbon tetrachloride dissolved in the
groundwater, and assists in identifying the location of the unaccounted carbon tetrachloride
disposed in the 200 West Area.
HI.  HIGHLIGHTS OF COMMUNITY PARTICIPATION

DOE, Ecology, and EPA (the Parties) developed a Community Relations Plan (CRP) in April
1990 as part of the overall Hanford Site restoration.  The CRP was designed to promote
public awareness of the investigations, and promote public involvement in the decision-
making process. The CRP summarizes concerns that the Parties are aware of based on
community interviews. Since that time, the Parties have held several public meetings and
sent out numerous fact sheets in an effort to keep the public informed about Hanford Site
cleanup issues. The CRP was updated in 1993 to enhance public involvement.

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                                      fig 2
                                   299-W7-5 ^ 299-W6-1
                                                        2000-3000 ppb
-N-
  5OO    1OOO

METERS

  15OO  30OO
  •   I
  FEET
 •  Well Location

 rm Area of 2000 to 3000 ppb
 \M groundwoter contamination.

 KjS Area of >3000 ppb
 Sis groundwoler contamination.

MO-. Concentration tsopleth (ppb)
Detection Limit	5 ppb

Drinking Water Standard	5 ppb

Washington Water Quality Std . . 0.3 ppb

Concentration Values Shown ore
Average Values for the Period

1/1/93 -  10/1/94

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The 200 West Groundwater Aggregate Area Management Study Report, the Interim Remedial
Measure Proposed Plan for the 200-ZP-l Operable Unit, Hanford, Washington, and the
Engineering Evaluation/Conceptual Plan for the 200-ZP-l Operable Unit Interim Remedial
Measure were made available on October 17, 1994 to the public in both the Administrative
Record and the Information Repositories maintained at the locations "listed below:

A fact sheet, which explained the proposed action, was mailed to approximately 2,000
people.  In addition, an article appeared in the bi-monthly newsletter, the Hanford Update,
detailing the start of public comment.  The Hanford Update is mailed to over 5,000 people.
The Proposed Plan was mailed  to all people on the Hanford Advisory Board mailing list.

      ADMINISTRATIVE RECORD (contains all project documents)

             U.S. Department of Energy
             Richland Field Office
             Administrative Record Center
             740 Stevens Center
             Richland, Washington 99352

             EPA Region 10
             Superfund Record Center
             1200 Sixth Avenue
             Park Place Building, 7th Floor
             Seattle, Washington 98101

             Washington State Department of Ecology  j
             Administrative Record                   '
             719 Sleater-Kinney Road SE             i
             Capital Financial Building, Suite 200
             Lacey, Washington 98503-1138           •

       INFORMATION REPOSITORIES (contains limited documentation)

             University of Washington
             Suzzallo Library
             Government Publications Room
             Mail Stop FM-25
             Seattle, Washington  98195

             Gonzaga University
             Foley Center
             E. 502 Boone
             Spokane, Washington  99258

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             Portland State University
             Branford Price Millar Library
             Science and Engineering Floor
             SW Harrison and Park
             P.O. Box 1151
             Portland, Oregon  97207

             DOE Richland Public Reading Room
             Washington State University, Tri-Cities
             100 Sprout Road, Room 130
             Richland, Washington 99352
The notice of the availability of these documents was published in the Seattle Pi/Times, the
Spokesman Review-Chronicle, the Tri-City Herald, and the Oregonian on October 16,  1994.
The public comment period was held from October 17, 1994, through November 30, 1994.
This decision document presents the selected interim remedial measure for the 200 ZP-1
operable unit at the Hanford Site, Richland, Washington, chosen in accordance with
CERCLA, as amended by SARA, and to the extent practicable, the NCP. The decision for
this site is based on the Administrative Record.  As part of the Proposed Plan a public
meeting was offered to be held if requested.  No such requests were received by EPA. In
addition, the Proposed Plan was discussed at the Hanford Advisory Board's November
meeting. This meeting is advertised and is open to the public. The public is encouraged to
comment during these meetings. No members of the public, outside the advisory board,
commented on the Proposed Plan at the  meeting.
IV.  SCOPE AND ROLE OF RESPONSE ACTION WITHIN SITE STRATEGY

This action is being taken in an effort to address one of the most serious groundwater
problems on the Hanford Site.  It is believed that, by reducing the mass of contaminants
within the high concentration plume, the potential for spread to an offsite receptor above a
risk threshold can be reduced or eliminated. This action will facilitate investigation of 200-
ZP-1 Operable Unit by providing information about aquifer parameters based on data from
the groundwater extraction and monitoring wells.  In addition, this interim action will
provide site specific performance information that can be used to evaluate alternative
technologies, determine optimum process sizing, and estimate costs. This interim remedial
action is expected to be consistent with planned future actions. Because this interim action is
not the final remedy for the 200-ZP-l Operable Unit, additional action may be necessary to
address the potential threats posed by this site.

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V.  SITE CHARACTERISTICS

A.  Site Geology and Hydrology

1. Geology

The Hanford Site is located in the Pasco Basin, which is a topographic and structural basin
situated in the northern portion of the Columbia Plateau. The plateau is divided into three
general structural subprovinces: the Blue Mountains; the Palouse; and, the Yakima Fold
Belt.  The Hanford Site is located near the junction of the Yakima Fold Belt and the Palouse
subprovinces as shown  in Figure 3.

The 200 Area is located in the center of the Hanford Site.  The geologic structure beneath
the 200 Area is similar to much of the rest of the Hanford Site, which consists of three
distinct levels of soil formations. The deepest level is a thick series of basalt flows that have
been warped and folded, resulting in protrusions that crop out as rock ridges in some places.
Layers of silt, gravel, and sand (known as the Ringold Formation) form the middle level.
The uppermost level is  known as the Hanford formation and consists of gravel and sands
deposited by catastrophic floods during glacial retreat.  A geologic cross section for the 200
West Area is shown in Figure 4. Both confined and unconfined aquifers can be found
beneath the Hanford Site.

2. Hydrology

In the 200 West Area,  the uppermost aquifer is located in the Ringold Formation and
displays unconfined to locally-confined or semi-confined conditions.  The depth to
groundwater ranges from approximately 58 meters to 82 meters in the 200 West Area.  In
the area near the carbon tetrachloride disposal sites the depth to groundwater is from 60 to
66 meters.  The saturated thickness of the unconfined aquifer around the Plutonium Finishing
Plant is approximately  67 meters.  Groundwater recharge to! the aquifer below the 200 Area
has been primarily from process effluents.  The hydraulic conductivity for the Ringold
Formation varies widely.  It is estimated that the hydraulic conductivity ranges from 0.03 to
 183 meters/day. The Ringold Formation is made up of a series of alluvial sands and gravels.
Groundwater flow direction is thought to be from the southwest.
 B. Nature and Extent of Contamination

 The 200 West Area is an operational area of approximately 5.1 square kilometers where
 spent nuclear fuel was processed in four main facilities: U Plant (primarily uranium
 recovery); Plutonium Finishing Plant (PFP) (primarily plutonium separation and recovery);
 and S and T Plants (primarily uranium and plutonium separation from irradiated fuel rods).

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                                 fig  3

                  Geologic Structure of the Hanford Site
Rattlesnake Mountain
Anticline
| ~^~ [? J* 1 1 Basalt Outcrop """* ^
1 H
0 10km t
Ii _»
i ^^
I ^
1 0 6 mi
L_ /^
— Syncllne / V^^
/ /**
Boundary of the
Anticline Pasco Basin
r
H9106011.8b

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                                                                              2 Plant
VO
oifi7in 91R71A Plutonium 216-2-9
\<>*.jl>^v/v/v/v/v/v/\^/xt>^^^>>>X;^^^^
X/N/\» ////// /-V /-/ A/ / / <> t.f.t-.t.,t t t t / / / *.f *.f' '.'.'*'.'.''.''.' '.'''.'SSS*
/ / / / /
\\NSS
VN'N'N'N
t t t t f
i. '| • H9406009.12
E3 Basalt
^••••••^ Gravel ; .
[•'Pl'Ki Sand
^'v-N Mud
Generalized Southwest-Northeast Geologic Cross Section
Elevation
(feet above mean sea level)
0 0 O
0 O 0 0
o u> o o
CM T- T- m o

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Mixtures of carbon tetrachloride containing other organics were used at PFP to recover
plutonium from the processing waste streams.  Spent carbon tetrachloride mixtures were
discharged to the ground at the 200 West Area. Approximately 600 to 1,000 metric tons of
carbon tetrachloride waste were discharged to the ground between 1955 and 1973, resulting
in extensive contamination of the soil and groundwater beneath the 200 West Area.  Elevated
concentrations of chloroform and TCE are also found generally coincident with the carbon
tetrachloride in  the groundwater.  Although these chemicals are not known to have been used
in plutonium recovery processing, the association of the three chemicals suggest some
linkage.  Chloroform may be a degradation product of carbon tetrachloride, while TCE may
have been used  as a maintenance chemical. It has been determined that a portion of the
carbon tetrachloride was used as a degreaser and if removed, this waste may be classified as
a listed dangerous waste.  However, as long as substantial reduction of concentration of
hazardous substances is accomplished prior to reinjection into the aquifer,  and such
reinjection is protective of human health and the environment, reinjection of such treated
effluent classified as dangerous waste is allowed under RCRA Section 3020 (b).

Groundwater occurs about 64 meters below the ground surface and generally flows from
west to east beneath the 200 West Area.  However, historic discharges of large volumes of
waste water have created an artificial groundwater  mound that causes groundwater
contaminated with carbon tetrachloride, chloroform, and TCE to flow towards the north and
northeast of 200-ZP-l.

Monitoring programs have been in place for many  years at the Hanford Site. Information
from these monitoring programs was used to determine that an action was needed at 200-ZP-
1.  Carbon tetrachloride is distributed in a plume that extends under most of the 200 West
Area, although  the highest concentration areas of the plume are located within 200-ZP-l.
The maximum average concentration of carbon tetrachloride found in one well in 200-ZP-l
groundwater is  approximately 7,000 parts per billion (ppb).  Some of the carbon tetrachloride
may be present in the aquifer as dense non-aqueous phase liquids (DNAPL).  Chloroform is
generally associated with the carbon tetrachloride in its areal distribution;  its greatest
measured average concentration in the groundwater is currently about 170 ppb. TCE is
distributed in three  smaller plumes that are not as clearly associated with the carbon
tetrachloride plume, TCE is found in the groundwater at concentrations up to about 25 ppb.

Plutonium was  also discharged to the soil column as part of the waste stream.  However,
monitoring indicates that almost all of the plutonium has bound to the soil column and little
has reached the groundwater.

Since late 1990, DOE has been conducting a removal action in the 200 West Area to remove
carbon tetrachloride from the unsaturated soils between the ground surface and water table so
as to minimize further  movement of the carbon tetrachloride to uncontaminated areas.  The
removal action is being taken to ensure that the environment and public health are adequately
protected, and  to reduce the threat of further groundwater  contamination.  This action has
contributed significant  information regarding the origin, nature, and extent of carbon


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tetrachloride, as well as other site characteristics needed for evaluating remedial alternatives
for both source and groundwater operable units in the 200 West Area.
VI.  SUMMARY OF SITE RISKS

During the assessment and information gathering phase, DOE performed an initial risk-based
screening, as well as a comparison of known contaminant concentrations in 200-ZP-l
groundwater against pertinent federal and state groundwater standards.  The risk-based
screening was qualitative in nature and was designed to prioritize contaminant plumes. The
screening concluded that carbon tetrachloride, chloroform, and TCE present a high potential
risk due to their carcinogenic characteristics, and that these contaminants had been
consistently detected in the groundwater at concentrations that significantly exceeded drinking
water standards. It should be noted that the contaminated groundwater in 200-ZP-l is not
currently used as a drinking water source.

Carbon tetrachloride is acutely  toxic and has been reported in toxicological literature to cause
nerve and liver damage in humans; animal studies indicate that carbon tetrachloride can cause
liver tumors. Carbon tetrachloride has been found to exceed the Maximum Contaminant
Level (MCL) for drinking water of 5  ppb by more than 1,000 times in 200-ZP-l
groundwater.  Chloroform is acutely toxic, has been reported in toxicological literature to be
a possible mutagen and teratogen, and is a suspected carcinogen. Chloroform has been
found to exceed the MCL of 100 ppb in 200-ZP-l  groundwater. TCE is moderately toxic,
has been reported in toxicological literature to damage the liver and other organs, and is a
suspected carcinogen.  TCE has been found to exceed the MCL of 5 ppb by almost 5 times
in 200-ZP-l groundwater.                               1
VEL REMEDIAL ACTION OBJECTIVES
                                                       (
                                                      - i
Interim remedial actions conducted during this action will focus on removing the contaminant
mass from the unconfined aquifer and controlling movement of these contaminants in the
groundwater out of the 200 West Area.  Specific objectives of the interim action include the
following:

•     Reducing contamination in the area of highest concentrations of carbon tetrachloride.

•     Preventing further movement of these contaminants from the highest concentration
       area.

•     Providing information that will lead to development of a final remedy that will be
       protective of human health and the environment.
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Major applicable or relevant and appropriate requirements (ARARs) include drinking water
standards, state effluent discharge standards, solid and hazardous waste designation and
management standards, and air emission standards (e.g., for venting releases from tanks or
piping).  An IRM is an interim action designed to reduce risk through contaminant mass
reduction.  This action is an interim measure which will become part of a total remedial
action that will attain all applicable or relevant and appropriate requirements as provided for
in Section 121 of CERCLA.

The treated groundwater will be re-introduced into the aquifer via wells located within the
plume boundary.  The goal of this action, as detailed in the Proposed Plan, is to remove the
three primary contaminants from the effluent stream to meet the established MCLs. It should
be noted that there is a potential for nitrate levels in the treated groundwater to be above the
drinking water  standard.  However, because the scope of this action is for removal of carbon
tetrachloride, chloroform, and TCE, discharges of nitrates and radionuclides are not
addressed in this interim action.
       DESCRIPTION OF ALTERNATIVES

Alternative 1: No Action

This alternative would consist of allowing contaminants to migrate, dissipate, and naturally
degrade over time until a final remedy is selected and implemented.

Alternative 2: Groundwater Pump and Treat

This alternative will consist of extracting groundwater; treating it to remove carbon
tetrachloride, TCE, and chloroform; and then returning the treated water to the aquifer.
Treated groundwater would be returned through wells that are situated to help control
migration of contaminants from  the high concentration portion of the plume.  This alternative
would occur in the following phases:

•      The first phase consists of pilot-scale operations (up to a capacity of about 190 liters
        per minute ((50 gallons per minute) and focused data collection activities (i.e.,
        refinement of the hydraulic properties of the aquifer) to support remedial design.
        Pilot-scale treatment operations are underway to evaluate liquid-phase granular
        activated carbon. Design studies are underway to evaluate the effectiveness of air
        stripping and vapor-phase granular activated carbon.Pilot-scale treatment operations
        will provide system and engineering data in three key areas:  process effectiveness;
        operating parameters; and resource requirements.  Information on these areas will
        allow optimization of the treatment system(s) and will support phased expansion of the
        pump and treat system (discussed below).  It should be noted that a pilot scale
        treatability test began August 29, 1994. The pilot-scale system will continue to
        operate as Phase I of this IRM until October 1995 when the next system will be


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available to begin Phase n. Phase I of this action will not meet the standard for
secondary containment for tank systems. However, because Phase I is a continuation
of the treatability test system and operation is short in duration, the current treatability
test system will be allowed to continue without secondary containment for tank
systems. Therefore, an interim action waiver for secondary containment is invoked
for Phase I operations.  This interim action waiver will cease to exist when Phase n
operations is initiated as Phase n operations will meet the secondary containment
standards for tanks.

Subsequent phases will expand the pump and treat system, additional wells will be
installed, and the effects of the pump and treat will be monitored.  The degree of
expansion will be based on the amount of groundwater extraction and treated water
reinjection that is deemed necessary to contain  the high concentration area.  It is
estimated that the first phase of this expansion  (Phase n) will upgrade the total pump
and treat capacity to about 570 liters per minute (150 gallons per minute). This
system will  be operated to continue gathering data on the effects of pump and treat on
plume containment and mass removal.  Monitoring will be performed during Phase n
operations to determine optimal groundwater withdrawal and return rates; a refined
knowledge of contaminant distribution within the aquifer; knowledge of spacing
requirements for the network of wells to support the pump and treat; and whether or
not ongoing sources of contaminants exist that  might not be addressed by pump and
treat.

 A final phase of expansion (Phase HI) will be initiated in fiscal year 1998, resulting
in a pumping rate in the range of 570 to 1,900 liters per minute (150 to 500 gallons
per minute) to meet the objectives of this interim action. Pump-and-treat operations
will continue until selection of a final remedy,  or until DOE demonstrates to EPA that
further  interim action pump and treat is no longer required to protect human health
and the environment. It is anticipated that this action will continue until at least the
year 2000.  Additional wells will be installed for extraction and return, and for
monitoring  progress of the pump-and-treat activities.  Up to 19 wells may need to be
installed to  support this action. In addition to  the focused monitoring that will be
performed during the data collection activities, ongoing monitoring will occur
throughout  the interim action activities.  Additional information will be collected to
support the expansion on an as-needed basis.

The water will be discharged through wells located at 200-ZP-l. The contaminant
levels remaining in the effluent will meet the drinking water standards of the three
contaminants addressed by this IRM.

 All other waste generated during this  action will be handled per DOE and EPA
 approved waste management practices.  Spent carbon canisters will be either
 regenerated or disposed of at an approved facility. Contaminated  clothing,
 equipment, and other waste material will either be shipped to an appropriate


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      facility or if the material exceeds the disposal facility acceptance criteria it will
      be stored at the waste site accumulation area until the material is treated to
      meet acceptance criteria or DOE requests a treatability variance from EPA and
      it is approved.
IX. SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES

A. Threshold Criteria

1. Overall Protection of Human Health

The no-action alternative does not change the overall protection of human health and the
environment.  Alternative 2 would remove contaminant mass from the aquifer and contain
the high concentration area of the plumes. Therefore, it will improve overall protection of
human health and the environment.

2.  Compliance with ARARs

Major applicable or relevant and appropriate requirements (ARARs) include drinking water
standards, state effluent discharge standards, solid and hazardous waste designation and
management standards,  and air emission standards (e.g., for venting releases from tanks or
piping).  An IRM is an interim action designed to reduce risk through contaminant mass
reduction. This action is an interim measure which will become part of a total remedial
action that will attain all applicable or relevant and appropriate requirements as provided for
in Section 121 of CERCLA.

The no-action alternative would not invoke any ARARs that would need to be satisfied.

Alternative 2 is intended to meet the drinking water standards, state effluent discharge
standards, and RCRA hazardous waste management standards of the three primary
contaminants. By reducing the mass of the three primary contaminants it will reduce the
further degradation of groundwater in the 200 West Area.  Secondary waste and other
materials generated during implementation of Alternative 2, as well as potential air  releases,
would be managed to satisfy ARARs.


B. Primary Balancing Criteria

3. Long-Term Effectiveness and Permanence.  The no-action alternative provides no long-
term  effectiveness or permanence. Alternative 2 would not, by itself, achieve long-term
effectiveness and permanence.  However, contaminant removal and containment through
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pump-and-treat would provide a long-term and permanent reduction in risk and in
contaminant migration.  At the same time, Alternative 2 would improve the potential for
future final remedies to be implemented that will achieve long-term effectiveness and
permanence.

4. Reduction of Toxicity, Mobility, or Volume.  The no-action alternative provides no
reduction of toxicity, mobility, or volume through treatment.  Alternative 2 would provide
treatment of the groundwater contaminants,  thereby reducing the volume of contaminants that
may migrate and reducing the overall toxicity risk of the groundwater.

5. Short-term Effectiveness.  The no-action alternative has no short-term effect on the
contamination.  Alternative 2 would offer short-term effectiveness by limiting the migration
of the contamination and by reducing contamination in the areas of highest concentration.

6. Implementability.  The no-action alternative is easily implemented, because no changes
would be made to the site. Alternative 2 could be implemented using available technology.
It would be necessary to demonstrate and optimize both the pumping and treatment aspects of
Alternative 2 in order to accomplish an efficient and effective implementation.

7.  Cost.  The no-action alternative has essentially no added cost. The cost estimates  for
Alternative 2 are presented in Table 2. These estimates are based on various assumptions,
including (among others), the following:

       •     Procurement of three air stripping/vapor phase activated carbon adsorption
             treatment systems, operating  at a total capacity of 1,900 liters pre minute
             (500 gallons per minute)                 I

       •     Installation of a total of 10 new extraction, J5 injection, and 4 monitoring wells

       •     Focused data collection and monitoring activities as detailed in Section VHI.
                                                    i
8. State Acceptance.  The State of Washington supports Alternative 2.

9. Community Acceptance.  This action was first proposed as part of the fourth amendment
to the Tri-Party Agreement and received favorable public comments. Final community
acceptance of the alternatives was evaluated during the public comment period.  There
appears to be community support for this action.  A summary of public comments on the
Interim Remedial Measure is  provided in the Responsiveness Summary attached to this
Interim Action  ROD.
                                          15

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The selected remedy uses groundwater pump and treat and is intended to minimize further
migration of carbon tetrachlohde, chloroform, and trichloroethylene (TCE) in groundwater at
the 200 West Area.  To do this, the IRM is designed to stabilize and  reduce contaminant
mass in the high concentration portion of the plume.  The nigh concentration portion of the
plume corresponds to the area within the 2000 - 3000 parts per billion (ppb) contour of
carbon tetrachloride.

This interim action will be implemented in a phased approach. Phase I operations will be to
continue the operation of the treatability test system.  Phase I of this action will not meet the
RCRA standard for secondary containment.  However, because Phase I is a continuation of
the treatability test system and operation is short in duration, the current treatability test
system will be allowed to continue without secondary containment for tank systems.
Therefore, an interim action waiver for secondary containment is invoked for phase I
operations.  This interim action waiver will cease to exist when Phase n operations is
initiated as Phase n operations will meet secondary containment standards for tank systems.
Subsequent phases will expand the pump and treat system, additional wells will be installed,
and the effects  of the pump and treat will be monitored. The degree of expansion will be
based on the amount of groundwater extraction  and treated water reinjection that is deemed
necessary to contain the high concentration area.  It is estimated that the first phase of this
expansion (Phase n) will upgrade the total pump and treat capacity to about 570 liters per
minute (150 gallons per minute). Up to three new wells may need to be installed to support
scale up to 570 liters per  minute (150 gallons per minute).  This system will be operated to
continue gathering data on the effects of pump and treat on plume containment and mass
removal. Pumping efforts will be increased if outward migration of  the plume is observed.

In fiscal year 1998, phase ffl will be completed, resulting in a pumping rate in the range of
570 to  1,900 liters per minute (150 to 500 gallons per minute) as needed to meet the
objectives of this interim action. Initial estimates show that up to 19 new wells may need to
be installed to  support full-scale pumping operations. Pump-and-treat operations will continue
until selection of a final remedy, or until DOE  demonstrates to EPA that further interim
pump and treat operations will no longer be required to protect human health and the
 environment.  It is anticipated that this action, if successful, will continue until at least the
 year 2000.

 In addition to the focused monitoring that will be performed during the data collection
 activities, ongoing monitoring will occur throughout the interim action activities.  Additional
 information will be collected to support the expansion , on an as-needed basis.

 The  treatment  train for Phase n (treatment system upgraded to 570 liters per minute (150
 gallons per minute)) and Phase ffl (treatment system upgraded up to 1,900 liters per minute
 (500 gallons per minute)) of this interim remedial measure is air stripping with vapor phase
 activated carbon used to capture stripped contaminants. The treated groundwater will be


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reinjected into the aquifer through wells located within the area of contamination and will
meet the discharge criteria for the three primary contaminants.

All other waste generated during this action will be handled per DOE and EPA approved
waste management practices.  Spent carbon canisters will be either regenerated or disposed
of at an approved facility. Contaminated clothing, equipment, and other waste material will
either be shipped to an appropriate facility  or if material exceeds the disposal facilities waste
acceptance criteria the material will be stored at the waste site accumulation area  until the
material is treated to meet the acceptance criteria or DOE requests a treatability variance
from EPA and it is approved.

In addition to the pump and treat action, a  DNAPL investigation will occur at the 216-Z-9
trench area.  If DNAPL's are found, appropriate response actions will be determined and this
ROD will be modified as necessary.
XL  STATUTORY DETERMINATIONS

Under CERCLA Section 121, selected remedies must be protective of human health and the
environment, comply with ARARs, be cost effective, and utilize permanent solutions and
alternative treatment technologies or resource recovery technologies to the maximum extent
practicable.  In addition, CERCLA includes a preference for remedies that employ treatment
that significantly and permanently reduces the volume,  toxicity, or mobility of hazardous
wastes as their principal element. The following sections discuss how the selected remedy
meets these statutory requirements.

A. Protection of Human Health and the Environment

The selected interim remedy helps protect human health and the environment by removal and
treatment of contaminated groundwater.  Implementation of this remedial action will not pose
unacceptable short-term risks to site workers.  The selected remedy is the best alternative as
it uses proven  technology and, if successful, will remove significant amounts of contaminants
from the aquifer.
 B. Compliance with ARAR's

 The following state and federal ARARs have been identified for this interim remedial
 measure:

       Chemical-Specific ARARs

       •  Safe Drinking Water Act (SDWA), 40 CFR Part 141, Maximum Contaminant
          Levels (MCLs) for public drinking water supplies are relevant and appropriate for


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   setting groundwater cleanup levels and evaluating the effectiveness of the
   treatment train.  The treatment train will be designed to meet MCLs for carbon
   tetrachloride, chloroform and TCE.

Action-Specific ARARs

•  RCRA Land Disposal Restrictions (40 CFR 268) are applicable for secondary
   waste (protective clothing, sampling equipment etc..) which comes in contact with
   the contaminated water.

•  Minimum Standards for Construction and Maintenance of Wells (Chapter 173-160
   and 162 WAC) Applicable regulations for the location, design, construction, and
   abandonment of water supply and resource protection wells.

•  RCRA Subtitle C (40 CFR 262) establishes standards for generators of hazardous
   wastes for the treating, storage, and shipping of wastes.  Applicable to the
   transportation of hazardous wastes.

•  RCRA Subtitle C (40 CFR 264) Hazardous waste treatment, storage, and disposal
   applicable to design and operation of treatment system.

   Phase I of this action will not meet the standard for secondary containment for
   tank systems. However, because Phase I is a  continuation of the treatability test
   system and operation is short in duration, the current treatability test system
   will be allowed  to continue without secondary containment for tank systems.
   Therefore* an interim action waiver for secondary containment is invoked for
   Phase I operations. This interim action waiver will cease to exist when Phase
   n operations is initiated as Phase n operations will meet secondary
   containment standards for tank systems.

• RCRA Section 3020 governs the reinjection of hazardous waste into an aquifer.
   Applicable.  This interim action will meet the requirements of RCRA Section
   3020. Therefore,  reinjection of this listed waste into the aquifer is allowed.

•  Washington Administrative Code (WAC 173-303), state dangerous waste
   regulations, applicable for the handling of all  secondary waste.

•  Washington Administrative Code (WAC 173-218), state underground injection
    standards.  Relevant and appropriate for the reinjection of water back into the
    aquifer.

•  Radioactive Airborne Emissions (40 CFR Part 264, Subpart H); would be
    applicable if radionuclides are encountered in  the groundwater. To date, no
    radionuclides have been detected in the groundwater plume.

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         Washington Administrative Code (WAC 173-460), establishes acceptable source
         impact levels for carcinogenic and acutely toxic air pollutants. This is applicable
         and this action will achieve discharge criteria by absorbing the contaminants on
         granulated activated carbon.
      Location-Specific ARARs

      •  National Historic Preservation Act (16 CFR 470, et. seq.) Applicable for any
         intrusive work.

      •  Endangered Species Act (16 U.S.C. 1531 etseq.) Applicable for any work which
         may impact a listed species.

      Other Criteria, Advisories, or Guidance to be Considered for this Remedial
      Action (TBCs)

      •  EPA OSWER 9234.1-06, Applicability of Land Disposal Restrictions to RCRA and
         CERCLA Ground Water Treatment Reinjection Superfimd Management Review:
         Recommendation No. 26. dated December 27,  1989.  This directive provides
         guidance on issues regarding whether land disposal restrictions apply to reinjection
         of groundwater. In general, this guidance states that EPA construes the provisions
         of RCRA Section 3020 to be applicable instead of LDR provisions contained in
         RCRA Sections 3004 (f), (g), and (m), to reinjection of contaminated groundwater
         into an underground source of drinking water which is part of a CERCLA
         response action.                            '

      •  The Future For Hanford: Uses and Cleanup, The Final Report of the Hanford
         Future Site Uses Working Group, December 1992.

C.  Cost Effectiveness

The selected remedy provides overall effectiveness .proportional to its cost. Estimated costs
are summarized on Table 1.
D.  Utilization of Permanent Solutions and Alternative Treatment Technologies to the
    Maximum Extent Possible

Because this action does not constitute the final remedy for this operable unit, the statutory
preference for remedies that employ treatment that reduces toxicity, mobility, or volume as a
principal element, although partially addressed in this remedy, will be addressed by the final
response action.  Subsequent actions are planned to address fully the threats posed by
conditions at this operable unit.


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              Table  L
                             200-ZP-l IRM Cost Estimate.

Capital
Well Installation
Operations &
Maintenance
Sampling, Analysis
and Monitoring
DNAPL Investigation2
Escalation
Total1
FY 1995
860,000
900,000
1,140,00
0
1,970,00
0
690,000
0
5,560,00
0
FY 1996
750,000
2,700,00
0
980,000
9io;ooo
300,000
120,000
5,760,00
0
FY 1997
750,000
2,700,00
0
980,000
910,000
0
250,000
5,590,00
0
FY 1998
0
0
980,000
910,000
0
130,000
2,020,00
0
FY 1999
0
0
980,000
910,000
0
170,000
2,060,00
0
FY2000
0
0
980,000
910,000
0
220,000
2,110,00
0
lNo contingency included                    .
Includes deepening two existing wells for use as IfeM monitoring wells.
                                      20

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E. Preference for Treatment as a Principal Element

The selected remedy utilizes an effective treatment process for the removal of carbon
tetrachloride, TCE,  and chloroform from groundwater.

XH. DOCUMENTATION OF SIGNIFICANT CHANGES

EPA reviewed all written and verbal comments submitted during the public comment period.
Upon review of these comments, it was determined that no significant changes to the selected
remedy, as originally identified in the Proposed Plan, were necessary.
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      USDOE HANFORD 200 WEST AREA 200-ZP-l OPERABLE UNIT

                         RESPONSIVENESS SUMMARY
The U.S. Department of Energy, the U.S. Environmental Protection Agency, and the
Washington State Department of Ecology held a public comment period from October 17,
1994 through November 30, 1994 for interested parties to comment on the 200-ZP-l
Proposed Plan.  The plan presents the preferred alternative for the groundwater located in the
200-ZP-l operable unit of the Hanford Site 200 West Area.  The primary support documents
for this action are the 200 West Groundwater Aggregate Area Management Report and the
Engineering Evaluation/Conceptual Plan for the 200-ZP-l Operable Unit Interim Remedial
Measure.

This action was presented and discussed at the November and December Hanford Advisory
Board meetings.  These meetings were open to the public and the public was encouraged to
comment on issues.  No individual public meeting was held for this operable unit.  However,
the public was informed of the opportunity to comment on the Proposed Plan by publication
in the Seattle Post-Intelligencer/Seattle Times, the Spokane Spokesman Review-Chronicle,
the Tri-City Herald, and the Oregonian on October 16, 1994, and by mailing a fact sheet to
approximately 2,000 people. No member of the public requested a public meeting.

A responsive summary is required by the Comprehensive Response Compensation and
Liability Act (CERCLA), for the purpose of providing the agencies and the public with a
summary of citizens' comments and concerns about the site,  as raised during the public
comment period, and the agencies' response to those comments and concerns.

I. RESPONSIVENESS SUMMARY OVERVIEW. This section briefly describes the
background of the Hanford Site 200 West Area and  outlines the preferred alternative for the
200-ZP-l Operable Unit.

H. BACKGROUND ON COMMUNITY INVOLVEMENT AND CONCERNS. This
section provides a brief history of community interest and concerns regarding the 200-ZP-l
Operable Unit.

HI. SUMMARY OF MAJOR QUESTIONS AND COMMENTS RECEIVED DURING
THE PUBLIC COMMENT PERIOD AND THE AGENCDZS RESPONSE TO  THOSE
COMMENTS. This section summarizes the written comments submitted to the agencies and
the agencies responses to those comments.

IV.  REMAINING CONCERNS. This section discusses community concerns that the
agencies should be aware of as they  prepare to undertake remedial design and remedial
action in the 200-ZP-l Operable Unit.
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I. RESPONSIVENESS SUMMARY OVERVIEW

The Hanford Site was established in 1943 to produce plutonium for nuclear weapons using
nuclear reactors and chemical processing plants. Operations at the Hanford Site are now
focused on environmental restoration and waste management.

The 200 West Area is an operational area of approximately 8 square kilometer (3.2 square
miles) where spent nuclear fuel was processed in four main facilities: U Plant (primarily
uranium recovery); Plutonium Finishing Plant (primarily plutonium separation and recovery);
and S and T Plants (primarily uranium and plutonium separation from irradiated fuel rods).
The 200-ZP-l Operable Unit is located within the 200 West Area of the Hanford Site, and
was included on the National Priorities List in July 1989.

Mixtures of carbon tetrachloride containing other organics were used at the Plutonium
Finishing Plant to recover plutonium from the processing waste streams.  Spent carbon
tetrachloride mixtures were discharged to the ground at the 200-ZP-2 Source operable unit in
the 200 West Area. Approximately 600 to  1,000 metric tons of carbon tetrachloride waste
were discharged to the ground between 1955 and 1973, resulting in extensive contamination
of the soil and groundwater beneath the 200 West Area.  Elevated concentrations of
chloroform and TCE were also found generally coincident with the carbon tetrachloride.
Although these chemicals are not known to have been used in plutonium recovery processing,
the association  of the three chemicals suggest some linkage.  Chloroform may be a
degradation product of carbon tetrachloride, while TCE may have been used as a
maintenance chemical.                                 I
                                                     1
Some of the carbon tetrachloride, chloroform, and TCE have migrated through the soil
column and contaminated the groundwater underlying the 200 West Area.  Groundwater
occurs about 64 meters below the ground surface and generally flows from west to east
beneath the 200 West Area. However, historic discharges bf large volumes of waste water
have created an artificial groundwater mound that causes gfoundwater contaminated with
carbon tetrachloride, chloroform, and TCE to flow toward the north and northeast in 200-
ZP-l.  Carbon tetrachloride is distributed in a plume that extends under most of the 200
West Area, although the highest concentration areas of the plume are located within the 200 -
ZP-1.  The maximum average concentration of carbon tetrachloride found at a well in 200-
ZP-l groundwater is approximately 7,000 parts per billion (ppb).  Some of the carbon
tetrachloride may be present in the aquifer as dense non-aqueous phase liquids (DNAPL).
Chloroform is generally associated with the carbon tetrachloride in its area! distribution; its
greatest measured average concentration in the groundwater is currently about 170 ppb.
TCE is distributed in three smaller plumes  that are not as clearly associated with the carbon
tetrachloride plume; TCE is found in the groundwater at concentrations up to  about 25 ppb.

Since late 1990, DOE has been conducting a removal action at the 200 West Area, removing
carbon tetrachloride from the  unsaturated soils between the ground surface and water table so


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as to minimize or stabilize further movement of the carbon tetrachloride contaminant to
uncontaminated areas. The removal action is being taken to ensure that the environmental
and public health are adequately protected, and to reduce the threat of further groundwater
contamination. This action has contributed significant information regarding the origin,
nature, and extent of carbon tetrachloride, and other site characteristics needed for evaluating
remedial alternatives for both source and groundwater operable units in the 200 West Area.

During 1993, DOE completed an Aggregate Area Management process to compile and
evaluate available information about contamination in the 200 West Area.  This was done to
effectively address both the source and the groundwater contamination in the 200 West Area.
Recommendations generated from the aggregate area process included using interim actions
associated with interim measures and removals to accelerate cleanup and limit the potential
spread of contamination  where enough information is known.

In early 1994, EPA, Ecology, and DOE determined that the information and data gained
through the 200 West Groundwater aggregate report and the carbon tetrachloride removal
were sufficient to propose an interim pump and treat remedial action for 200-ZP-l.

n.  BACKGROUND ON COMMUNITY INVOLVEMENT AND CONCERNS

The public has been involved in the cleanup of the Hanford Site since the Hartford Federal
Facility Agreement and Consent Order was signed in 1989.  Over the past several years a
number of stakeholder work groups and task forces have been used to enhance decision
making at the Hanford Site.  In January 1994 the Hanford Advisory Board was established to
provide informed advice to the U.S. Department of Energy, U.S. Environmental Protection
Agency, and the Washington State Department of Ecology.

A consistent message delivered by interested citizens and affected Indian Nations is to take
early action on groundwater contamination and  protect the  Columbia River. Taking this
action will help support these desires.

m.   SUMMARY OF MAJOR QUESTIONS AND COMMENTS RECEIVED
       DURING THE PUBLIC  COMMENT PERIOD AND  THE AGENCIES
       RESPONSE TO THOSE COMMENTS

Comments received during the public comment period are presented in this section.
Responses to the comments follow each comment. Copies of all comment letters received
are attached to this responsiveness summary as Appendix A.

COMMENT 1. The Hanford Advisory Board endorses continuation of the 200-ZP-l
   pump and treat action.

RESPONSE: The agencies agree that this action should proceed.
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COMMENT 2. All returned effluent should meet the drinking water standard.

RESPONSE:  The drinking water standards will be met for the three primary contaminants
under this interim remedial action.  Other contaminants that may be in the returned effluent
are outside the scope of this action.

COMMENT 3. Pumping efforts should be increased if outward migration continues. This
requires the use of sufficient monitoring wells to measure conditions in both the groundwater
plume as well as the vadose zone cloud.  All monitoring wells must be sealed to prevent the
downward movement of contaminants.

RESPONSE: The agencies agree and if outward migration is seen, pumping volumes will
be increased.  All  wells will be sealed in accordance with applicable Washington State
regulations.

COMMENT 4: A DNAPL investigation must occur at the Z-9 crib. If DNAPLS are
encountered the agencies should take appropriate actions to mitigate the DNAPL source.

RESPONSE:  A DNAPL investigation will occur at the 216-Z-9 crib and if DNAPL's are
found appropriate  response actions will be evaluated.  If DNAPL's are found a revision to
this ROD may be  required.

COMMENT 5: The use of innovative technologies should be employed if any  prove out.
Included as innovative technologies are in situ bioremediation and in well vapor stripping.
                                                    t
RESPONSE:  The agencies agree and will incorporate projven innovative technologies as
part of the final remedy selection process.               ;

COMMENT 6: The Proposed Plan should have called out the in situ bioremediation and in
well vapor stripping as part of the interim remedial measures.

RESPONSE:  The above mentioned innovative technologies were excluded from the
Proposed Plan and interim measures because there is not enough information available on
these technologies. This may have led to confusion by  the public. Information gained
during technology development testing of these technologies may be used in making the final
remedy selection for this operable unit.

COMMENT 7:  Alternative two, groundwater pump and treat should be  addressed and
activated immediately.

RESPONSE:  The agencies agree and this action is proceeding as planned.
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IV. REMAINING CONCERNS

The main concern expressed by the public is in regards to the use of innovative technology in
the final cleanup of the 200-ZP-l groundwater. The public expects the agencies to continue
to explore and develop new technologies.
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