PB97-963117
EPA/541/R-97/041
November 1997
EPA Superfund
Explanation of Significant Difference
for the Record of Decision:
Selma Treating Co.,
Selma, CA
4/18/1997
-------
-------
SFUNO RECORDS CTR
1047-01124
EXPLANATION OF SIGNIFICANT DIFFERENCES AROQ01
DECLARATION
SITE NAME AND LOCATION
Selma Pressure Treating Superfund Site
Selma, California
STATEMENT OF BASIS AND PURPOSE
On September 24,1988, the United States Environmental Protection Agency ("EPA")
signed the Record of Decision ("1988 ROD") for the Selma Pressure Treating
Superfund Site in Selma, California ("Site"). This Explanation of Significant Differences
#2 ("ESD2") explains the significant differences between the remedial action selected in
the 1988 ROD, as changed by the Explanation of Significant Differences issued in 1993
(1993 ESD), and the remedial action which will be implemented at the Site. (The 1988
ROD and the 1993 ESD are collectively referred to herein as the "ROD".) It was
developed in accordance with Section 117 of the Comprehensive Environmental
Response, Compensation, and Liability Act ("CERCLA"), as amended, and 40 C.F.R.
300.435 © (2) (I) (55 Fed. Reg. 8666, 8852 March 8,1990) of the National Contingency
Plan ("NCP"). This decision is based on the administrative record for this Site.
SUMMARY
This ESD2 explains changes in certain remedial action details pertaining to the return of
the treated water to the aquifer as described in the ROD. The 1988 ROD selected a
groundwater remedy which would employ a conventional precipitation, coagulation, and
flocculation extraction and treatment process, with either reinjection or off-site disposal
of the treated effluent. Based on reconsideration of certain technical information during
the design phase and additional data gathered pursuant to the ROD, EPA proposes to
modify the remedy by using percolation ponds to return the treated water to the aquifer.
All other aspects of the selected groundwater remedy are as described in the ROD,
including the scope and the cleanup standards.
DECLARATION
This remedy remains protective of human health and the environment, and continues to
comply with applicable or relevant and appropriate federal and state requirements that
were identified in the 1988 ROD, the 1993 ESD, and this ESD2. The selected remedy
also remains cost-effective and continues to use permanent solutions and alternative
treatment technologies to the maximum extent practicable for this Site. Finally, the
-------
selected remedy continues to employ treatment that permanently and significantly
reduces the volume, toxicity, or mobility of hazardous wastes.
4-
Keith Takata, Director Date
Superfund Division
-------
SELMA PRESSURE TREATING SUPERFUND SITE
Explanation of Significant Differences
April 18, 1997
I. Introduction
On September 24, 1988, the United States Environmental Protection Agency
("EPA") signed the Record of Decision ("1988 ROD") for the Selma Pressure Treating
Superfund Site in Selma, California ("Site"). This Explanation of Significant Differences
#2 ("ESD2") explains the significant differences between the remedial action selected
in the 1988 ROD, as changed by the Explanation of Significant Differences issued in
1993 (1993 ESD), and the remedial action which will be implemented at the Site. (The
1988 ROD and the 1993 ESD are collectively referred to herein as the "ROD".) See
Attachments 1 and 2.
Pursuant to Section 117 of the Comprehensive Environmental Response,
Compensation, and Liability Act ("CERCLA"), as amended, and pursuant to 40 C.F.R.
300.435 © (2) (I) (55 Fed. Reg. 8666, 8852 March 8, 1990) of the National Contingency
Plan ("NCP"), EPA is required to publish an Explanation of Significant Differences
("ESD") when differences in the selected remedy "significantly change, but do not
fundamentally alter the remedy selected in the ROD with respect to scope,
performance, or cost." This ESD2 briefly describes the Site's location and history,
summarizes the remedy selected in the ROD, describes the differences between the
proposed changes and the ROD, and explains the basis for the changes.
This ESD2 explains changes in certain remedial action details pertaining to the
return of the treated water to the aquifer as described in the ROD. The groundwater
remedy selected in the ROD consists of a conventional pump-and-treat system which
would return the treated water to the aquifer via reinjection wells. EPA proposes to
modify the remedy by using percolation ponds to return the treated water to the aquifer.
All other aspects of the selected groundwater remedy are as described in the ROD,
including the scope and the cleanup standards.
This ESD2 and the supporting documentation will become part of the Selma
Pressure Treating Administrative Record. A copy of the Administrative Record has
been placed at the following locations:
Fresno County Library
Selma Branch
2200 Selma Ave.
-------
Selma, CA 93662
(209) 896-3393
U.S. EPA Region IX
Superfund Records Center
75 Hawthorne Street
San Francisco, CA 94105
(415) 536-2000
II. Site Description and History
Located in Fresno County, California, the Site is approximately 15 miles south of
the City of Fresno and adjacent to the southern city limits of Selma. The Site is
comprised of approximately 18 acres which include a 4-acre wood treatment facility and
14 acres of vineyards that were used for site drainage. The Site is located in a
transition zone between agricultural, residential, and industrial areas. Twelve (12)
residences and/or businesses are located within 1/4 mile of the site. As of November
1996, a small transmission repair business leases an open air garage within 200 feet of
the abandoned wood treatment facility. See Figure 1.
The wood preserving process originally employed at the site involved dipping
wood into a mixture of pentachlorophenol ("PCP") and oil, then drying the wood in open
racks to let the excess liquid drip off. In 1965, the wood treating operator converted to
a pressure treating process which consisted of conditioning the wood and impregnating
it with chemical preservatives. Chemical preservatives known to have been used at
the Site include fluor-chromium-arsenate-phenol, chromated copper arsenate, PCP,
copper-8-quinolinolate, LST concentrate, and Woodtox 140 RTU and Heavy Oil Penta
5% Solution. Prior to 1982, discharge practices for wastes generated from spent retort
fluids and sludges included: 1) runoff into drainage and percolation ditches; 2) drainage
into dry wells; 3) spillage onto open ground; 4) placement into an unlined pond and a
sludge pit; and 5) discharges to the adjacent vineyards. Wood treating operations
ceased in February 1994.
From 1971 to 1981, the Regional Water Quality Control Board ("RWQCB")
regulated the discharges from the facility pursuant to a Waste Discharge Requirements
Order. In January 1981, EPA, the RWQCB, and the predecessor to the California
Department of Toxic Substance Control ("DTSC"), the Department of Health Services
("DHS"), conducted an investigation in accordance with Section 3007 of the Resource
Conservation and Recovery Act which raised concerns regarding potential groundwater
contamination at the Site. In September 1983, the Site was placed on the National
Priorities List.
From 1981 to 1984, the RWQCB and DHS employed various enforcement tools
in an attempt to force the owners and/or operators to conduct response actions at the
-------
Site. In April 1984, DHS referred the Site to EPA for further action. EPA issued
Unilateral Administrative Orders ("UAOs") to the owners and/or operators of the Site to
conduct the work. The potentially responsible parties declined to comply with the UAOs
based upon an inability to fund the work.
In 1988, EPA issued a final Remedial Investigation and Feasibility Study which
characterized the soil and groundwater contamination at, and developed cleanup
standards for, the Site. In September 1988, EPA signed the 1988 ROD which, in
relevant part, identified chromium as the only significant contaminant in the
groundwater. Sampling results during the remedial investigation indicated that a plume
of chromium contamination extends downgradient from the Site to the southwest, with
the southern boundary of the plume approximately 1700 feet southwest of the facility.
Groundwater investigations conducted by EPA after the issuance of the 1988
ROD provided a more complete picture of the extent of contamination and the pumping
characteristics of the aquifer. Among other things, EPA's additional investigations
revealed that the groundwater table had dropped to elevations below the point where
EPA's original investigation had found the highest concentrations of chromium.
Sampling and analysis of the groundwater before the 1988 ROD had suggested that
PCP might be present in concentrations exceeding the then-newly promulgated, more
stringent drinking water maximum contaminant level ("MCL") of 1 part per billion ("ppb").
Based upon its recent groundwater monitoring studies, EPA has determined that any
concentrations of PCP in groundwater are below the current MCL of 1 ppb, and that
chromium is the only groundwater contaminant present in concentrations which exceed
the MCL of 50 ppb.
The 1988 ROD selected a groundwater remedy which would employ a
conventional precipitation, coagulation, and flocculation extraction and treatment
process, with either reinjection or off-site disposal of the treated effluent. The 1988
ROD established the cleanup standard for chromium to be 50 ppb.
In 1993, EPA issued the 1993 ESD which, among other things clarified language
in the 1988 ROD and explained certain changes to the selected groundwater remedy.
In relevant part, the 1993 ESD: 1) changed the term "cleanup goal" to "cleanup
standard" wherever it was used in the 1988 ROD; 2) set the cleanup standard for PCP
in groundwater at 1 ppb to comply with a new more stringent drinking water MCL
(initially the 1988 ROD did not establish a cleanup standard for PCP because the
California State action level of 30 ppm, which was considered a guideline, substantially
exceeded the concentrations detected in the groundwater); and 3) modified the
implementation of the groundwater extraction and reinjection system to reflect a more
phased, observational approach for the siting and design of the wells.
III. Description of Significant Differences and the Basis for Those Differences
-------
Based on reconsideration of certain technical information during the design
phase and additional data gathered pursuant to the ROD, this ESD2 changes the
manner in which treated water will be returned to the aquifer.
During the design phase, DTSC contended that there was insufficient data to
sufficiently predict the impact to the aquifer from reinjection of treated water.
Subsequently, EPA re-evaluated the groundwater treatment system and relevant data
and was concerned that the treated water, if recharged to the aquifer via reinjection,
might cause the plume of chromium concentration to spread laterally and/or vertically.
An added concern was that the change in hydrology attributed to reinjection of water
around the boundary of the plume could cause a loss of capture and reduce plume
containment, thereby allowing the plume to spread into new areas. Based on the
foregoing, EPA considered percolation as an alternative to reinjection because
percolation more closely mimics natural aquifer recharge, and thereby reduces the risk
of creating unwanted subterranean water movement or displacement of the
contaminated plume. Off-site disposal of the effluent to the irrigation district was also
considered, but this method was rejected because the irrigation district did not want the
water during the rainy season.
Additional data and review of the design for the groundwater remedy indicated
that percolation would be a preferable method for returning treated groundwater to the
aquifer. Pursuant to the ROD, EPA gathered additional field data using observation
wells and conducted a series of pilot percolation tests. The pilot percolation tests
primarily tested the hydraulic conductivity and measures the infiltration rates in the
subsurface soil. The results indicate that the infiltration rates are high enough to allow
for successful recharge of the treated groundwater to occur by percolation. The results
also indicate that returning the treated water to the aquifer via percolation would
minimize the effect on the underlying aquifer and plume of contamination. Based on
the foregoing, EPA determined that the Site conditions favor using a percolation pond
to recharge the aquifer. See Attachment 3.
Additional benefits are associated with opting for percolation versus reinjection.
First, the costs for construction and operation and maintenance of the percolation
ponds would be less than such costs associated with reinjection. The higher cost to
construct the reinjection system is attributable to the need to drill and develop eight
wells and a network of piping to connect these wells to the groundwater treatment plant.
The greater operation and maintenance costs for the reinjection system arise from the
cost of energy to pump water into the wells, the cost of increased maintenance
associated with the more extensive piping network, and the closure or removal of the
wells. In contrast, percolation ponds employ a simpler technology which would not
require additional wells or a pumping system, and would use a less extensive piping
system, resulting in lower costs. See Attachment 4.
Second, employing percolation ponds would confine the recharge system to the
Site, while the reinjection system requires that two wells and the associated piping be
-------
placed off-Site on neighboring properties. The reinjection system would require
individual access agreements for each of the neighboring parcels affected and added
security to oversee the off-Site system, in addition to coordination to minimize the
disturbances to the neighboring agricultural operations. Construction of the reinjection
system with eight new wells, six on-Site and two off-Site, would have a larger, more
lasting impact than the percolation system.
In light of the factors discussed above, EPA has determined that a percolation
pond recharge system is the preferred method for returning treated effluent to the
aquifer at this Site. DTSC has also accepted the concept of percolation over reinjection
for this Site. Such change will be implemented by a percolation system which will
discharge treated effluent into two percolation ponds. The dimensions of each pond
are two hundred feet by two hundred sixty feet (200'x260'). The ponds will be located
approximately four hundred feet east of the western site border, and two hundred to
four hundred south of the northern site border. See Figure 2.
The changes proposed in this ESD2 herein do not fundamentally alter the basic
features of the groundwater remedy with respect to scope, cost, or performance (40
CFR 300.435(c)(2)(ii)). The overall remedial approach to groundwater remains
extraction and treatment using conventional precipitation to remove the contaminant of
concern, chromium.
IV. Support Agency Comments
California DTSC has reviewed, and concurred on, the draft of this ESD2 before it
was sent out for public review.
V. Affirmation of the Statutory Determinations
This selected remedy remains protective of human health and the environment,
and continues to comply with applicable or relevant and appropriate federal and state
requirements that were identified in the 1988 ROD, the 1993 ESD, and this ESD2. The
selected remedy also remains cost-effective and continues to use permanent solutions
and alternative treatment technologies to the maximum extent practicable for this Site.
Finally, the selected remedy continues to employ treatment that permanently and
significantly reduces the volume, toxicity, or mobility of hazardous wastes.
VI. Public Participation
While neither CERCLA nor the NCP requires EPA to provide a period for public
comment in connection with this Explanation of Significant Differences, in light of
community interest in future land use, EPA intends to provide a period to allow for the
-------
public to comment on the changes discussed herein.
A public notice fact sheet describing this Explanation of Significant Differences
was distributed to people listed as interested community members for the Selma Site as
of April 23, 1997. The fact sheet summarized the changes proposed in the draft ESD2,
identified the repository in Selma where the entire text of the draft ESD2 could be
reviewed and provided a period for public comments from April 24 to May 23, 1997.
-------
FIGURES
-------
-------
CALIFORNIA
^ r i
a* '''^~~^~' \
Selma
Project Site
,. M J:l_....A^..-J
S - A
".!> ^ \
Se//na Pressure
Treating Site
north
01 Z 3 4 3
P
THOUSANDS OF
Selma Pressure Treating Site
Camp Dresser & McKee Inc.
-------
Bechtel Environmental, Inc
SELMA PRESSURE TREATING SUPERFUND SITE
RECHARGE BASIN
CONCEPTUAL DESIGN
-------
ATTACHMENT 1 SFUNO RECORDS CTR
1M7-00167
RECORD OF DECISION
FOR THE
SELMA PRESSURE TREATING COMPANY
SUPERFUND SITE
PREPARED BY
THE U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION IX
SAN FRANCISCO, CALIFORNIA
SEPTEMBER, 1988
-------
-------
TABLE OF CONTENTS
SELMA RECORD OF DECISION Pagt
Declaration for the Record of Decision 1
Decision Summary 3
I. Site Name, Description/ and Location 3
II. Site History and Enforcement Activities 5
III. Community Relations . 8
IV. Site Characteristics 9
A. Surface and Subsurface Soil Results ...9
B. Soil Clean-up Goals and Areas
Requiring Remediation 15
C. Groundwater Results 16
D. Groundwater Clean-up Goals 19
V. Summary of Site Risks 20
A. Chemicals of Concern 20
B. Exposure Pathways..... 21
C. Toxicity of Chemicals of Concern 21
D. Risk Characterization 22
E. Analytical Methods Used 24
VI. Documentation of Significant Changes/
Section 117(b)S(c) 24
VII. Description of Alternatives. 24
A. Alternative 1 24
B. Alternative 2 24
C. Alternative 3 ...26
D. Alternative 4 30
VIII. Summary of Comparative Analysis of Alternatives... 32
A. Overall Protection of Human Health and the
Environment 32
B. Compliance with ARARS 33
C. Long-term Effectiveness and Permanence 33
D. Reduction in Toxicity, Mobility, and Volume 33
E. Short-term Effectiveness 34
F. Implement ability .34
G. Estimated Capital, O&M, and Present Worth Cost 35
H. State and Community Acceptance 35
XI. The Selected Remedy 35
X. The Statutory Determinations 36
A. Protection of Human Health and the Environment 36
B. Attainment of ARARS 36
C. Cost-effectiveness. .37
D. Utilization of Permanent Solutions Employing
Alternative Technologies to the Maximum Extent
Practicable 38
-------
-------
-1-
DECLARATION FOR THE RECORD OF DECISION
SITE NAME AND LOCATION
The Selma Pressure Treating Company (SPT) site is located in
Selma/ California, 15 miles south of the City of Fresno, in
California's Central Valley.
STATEMENT OF BASIS AND PURPOSE
This decision document represents the selected remedial action
for the Selma Pressure Treating site, developed in accordance
with the Comprehensive Environmental Response, Compensation and
Liability Act of 1980, as amended, and the National Contingency
Plan. This decision is based on the administrative record for
this site. (The attached index identifies the items which
comprise the administrative record upon which the selection of
the remedial action is based). The State of California has
concurred on the selected remedy.
DESCRIPTION OF THE SELECTED REMEDY
This Record of Decision (ROD) for the Selraa Pressure Treating
site includes the following actions to address contaminated
soil and groundwater for the entire site (there are no operable
units):
0 Conventional water treatment to remove chromium from the
groundwater, including:
- Extraction of contaminated groundwater
Treatment of contaminated groundwater using precipitation,
coagulation, and flocculation processes to remove chromium
to meet the applicable drinking water standard
- Disposal of treated and tested groundwater by reinjection
into the aquifer or off-site disposal, as appropriate
Groundwater monitoring to verify contaminant clean-up
0 Soil fixation with a Resource Conservation and Recovery
Act (RCRA) Cap to treat contaminated soil, including:
Excavation of contaminated soils exceeding cleanup goals
Mixing soils with a fixative agent to solidify and stabilize
contaminated soil
Replacement of fixed soil into excavated areas and covering
the fixed areas with a RCRA Cap
-------
-2-
- Long term monitoring of fixed soils for a period of
approximately 30 years
Long-term access and land use restrictions for fixed
areas and short-term institutional controls to prevent
use of contaminated groundwater until remediation is complete
DECLARATION
The selected remedy is protective of human health and the envi-
ronment f attains federal and state requirements that are
applicable or relevant and appropriate to this remedial action
and is cost-effective. The groundwater remedy satisfies the
statutory preference for remedies that employ treatment that
reduces toxicity, mobility, or volume as a principal element and
utilizes permanent solutions to the maximum extent practicable.
The soil fixation/RCRA Cap element of this remedy is not considered
fully permanent/ due to the need for long-term monitoring. It
does employ treatment that significantly reduces mobility as a
principal element. However, toxicity is not reduced and volume
is increased due to addition of the fixative agent.
Because this remedy will result in hazardous substances remain-
ing on the site, a review will be conducted within five years after
commencement of the remedial action to ensure that the remedy con-
tinues to provide adequate protection of human health and the
environment. The State's letter of concurrence is attached.
Daniel W. McGovern Date
Regional Administrator
-------
-3-
DECISION SUMMARY
I. SITE NAME, DESCRIPTION, AND LOCATION
The SPT site is located about 15 miles south of Fresno and
adjacent to the southern city limits of Selma (Figure 1).
Dockery Avenue and Golden State Boulevard (old Highway 99)
mark the entrance to the site. The SPT site comprises
approximately 18 acres, including a 3-4 acre wood treatment
facility and 14 acres of adjacent vineyards that were used
for site drainage.
Zoned for heavy industrial use, SPT is located in a transition
zone between agricultural, residential, and industrial areas.
Situated in the center of the San Joaquin Valley, the area
contains many vineyards, and Selma is labeled the "Raisin
Capital of the World." Urban residential areas lie to the
north, and scattered suburban dwellings surround the site.
Approximately 12 residences and/or businesses are located
within 1/4 mile of the SPT site. Currently, a wood treating
facility, Selma Treating Company (STC), is operating at the
SPT site. STC is owned by Saw Mill Properties, Inc. STC
operations are regulated by state Waste Discharge Requirements
Order No. 78-171, which precludes discharges to areas
having hydraulic continuity with groundwater. At the time
STC began operating, the Regional Water Quality Control
Board (RWQCB) required installation of drip pads, berms
around the site, and runoff containment to prevent ongoing
contamination.
The Consolidated Irrigation District provides the majority of
the irrigation supply in the area. The surface water irriga-
tion supply is supplemented by groundwater resources in the
vicinity of the site. The groundwater resources also supply
the necessary domestic water for the surrounding communities
and the scattered county residences. The regional groundwater
gradient in the vicinity of the site is to the southwest.
The groundwater resources in the area of the SPT site have
been classified as a Sole-Source Aquifer by the U.S. Environ-
mental Protection Agency, under the Safe Drinking Water
Act, 42 U.S.C. §1424(e). Under EPA's Groundwater Protection
Strategy (1984), the aquifer in the SPT area has been classi-
fied as a Class II A current drinking water source with other
beneficial uses.
No other significant natural resources were found at SPT,
such as federal or state rare, threatened, or endangered
species, or wetlands. The site is not included on the
National Register of Historic Places under the Historic
Preservation Act of 1966, 16 U.S.C. §470 et. seq.
The climate for the site consists of hot summers and mild
winters. The maximum temperatures are generally around 100°F
in July, with a minimum temperature of 35° in January.
-------
1
CALIFORNIA
San
Francisco
Se/ma Pressure
Treating Site
,
......
r-/ i
norfh
01 2343.-
Selma Pressure Treating Site
REGIONAL LOCATION MAP
Camp Dresser & McKee Inc.
-------
-5-
Average annual precipitation in the area is less than 10
inches. The monthly evaporation losses range from two inches
per month during the winter to 18 inches per month during the
summer.
II. SITE HISTORY AND ENFORCEMENT ACTIVITIES
Treatment of lumber products has been ongoing at the SPT
site since 1942. The original wood treatment facility
covered approximately 3-1/2 acres. In 1961, the treatment
operation was taken over by Gerald Petery, the son of the
original owner, and his wife, Mary Ann Petery (now Schuessler).
A summary of the operating history of the Potential Responsible
Parties (PRP's) is as follows:
Dates
1961-1/1970
1/1970-12/1977
1971-Present
12/1977-late/1981
4/1981
2/1982
2/1982-Present
Owners
Gerald Petery and Mary Ann Petery operated
the facility as individuals.
Gerald Petery and Mary Ann Petery incor-
porated as Selma Pressure Treating
Company, which was responsible for
operating the facility.
Selma Leasing Company (SLC) was organ-
ized and owned by Gerald Petery. SLC
became the owner of the land upon
which SPT, and later Saw Mill Properties,
Inc., operated.
Gerald Petery sold his interest in SPT
to Mary Ann Schuessler (formerly Petery).
Mary Ann Schuessler became the sole
owner, president, and operator of SPT.
SPT filed for bankruptcy and First Inter-
state Bank or a trustee took over the
operation.
SPT's trustee sold wood treating assets
to Saw Mill Properties, Inc.
Saw Mill Properties, Inc. has operated
the facility, as Selma Treating Company.
The wood-preserving process originally employed at the site
involved dipping wood into a mixture of pentachlorophenol
and oil, and then drying the wood in open racks to let the
excess liquid drip off. A new facility was constructed
in 1965, and SPT converted to a pressure treating process
which consisted of conditioning the wood and then impregna-
ting it with chemical preservatives.
-------
-6-
Prior to 1982, discharge practices included: (1) runoff
into drainage and percolation ditches, (2) drainage into
dry wells, (3) spillage onto open ground, (4) placement into
an unlined pond and sludge pit, and (5) discharges to the
adjacent vineyards. These wastes were generated from spent
retort fluids and sludges. Figure 2 depicts these disposal
sites.
Between 1971 and 1981, the Regional Water Quality Control
Board (RWQCB) regulated the discharges from SPT, under a
Waste Discharge Requirements Order. An Uncontrolled
Hazardous Site Investigation was conducted on January 31, 1981
in accordance with §3007 of the Resource Conservation and
Recovery Act (RCRA), by the EPA's Field Investigation Team
(FIT), the California Department of Health Services (DBS),
and the RWQCB. This inspection raised concerns about the
potential for groundwater contamination from the site. As
a result, SPT was required to modify its operation to minimize
the potential for contamination. Initial site investigation
activities were then conducted by the state and EPA to
assess contamination problems.
Between 1981 and 1984, RWQCB, EPA, and DBS pursued efforts
to have SPT and, later, SLC investigate the site to determine
the extent of contamination. In September of 1981, the
RWQCB issued a Cleanup and Abatement Order to SPT, requiring
a geotechnical investigation and establishing a timetable for
cleanup. The timetable for cleanup was not submitted to the
RWQCB and in September of 1984, the RWQCB referred the
Order to the California Attorney General's office, for
enforcement. The Attorney General's office is pursuing a
case against SLC, SPT, Gerald Petery, and Mary Ann Schuessler,
on behalf of itself and the RWQCB. Gerald Petery has
filed a cross-claim against a number of parties, including
Mary Ann Schuessler, various chemical manufacturers of PCP,
EPA's consultant, COM, First Interstate Bank, Koppers, and
Osmose.
In September of 1983, DHS informed SPT of violations and
transmitted an Order, Settlement Agreement, and Schedule
of Compliance, including civil penalties of $75,000. In
December of 1983, DHS found SLC's counter proposal to this
Order to be unsatisfactory. DHS referred the site to EPA
for further action in April of 1984.
In August of 1983, EPA ranked the site using the Hazardous
Ranking System (HRS) 40 C.F.R. Part 300, Appendix A, as
authorized under 42 U.S.C. §105(a)(8), to determine whether
to include the site on the Superfund National Priorities
List of hazardous waste sites. The HRS ranking for the
site indicated that releases of hazardous substances from
the site may present a danger to human health and the environ-
ment. Based on this information the site was placed on the
Superfund National Priorities List of hazardous waste sites
in September 1983. The HRS ranking was 43.83, and the site
was listed as number 195.
-------
DATAMMMT N077B
-------
-8-
In September 1984, EPA requested Camp Dresser & McKee Inc.
(COM), under their REM II contract, to prepare a Work Plan
outlining the tasks required to prepare a Remedial Investi-
gation and Feasibility Study (RI/FS) for the site. COM
submitted the Work Plan outlining the RI/FS activities to
be conducted/ on June 7, 1985. The various project plans
required to support the field investigation activities
were submitted in 1985 and 1986. Field activities were
initiated in April 1986, and were conducted in various
phases through August 1987. The final RI report (COM, 1988)
provides the .results of those field activities. An Endanger-
ment Assessment (EA) was prepared to assess risks to human
health and the environment associated with the No Action
Alternative (ICF, 1988). The FS report (COM, 1988) analyzes
alternatives based on data collected and analyzed during the
RI investigation and based on the results of the EA.
Potentially Responsible Parties (PRPs) have not been involved
in development of the RI/FS. EPA is currently in discussion
with PRPs regarding the potential for their involvement in
the Remedial Design/Remedial Action (RD/RA) phases of this
project and for recovery of past costs. Special notice
letters will be issued in the near future under $122(e) of
CERCLA. PRPs identified include Gerald Petery, Mary Ann
Schuessler, and First Interstate Bank.
At present/ technical discussions with PRPs have been limited
to formal comments on the FS/Proposed Plan and related meet-
ings. This information is included in the responsiveness
summary and is part of the administrative record.
III. COMMUNITY RELATIONS
The following is a summary of community relations activities
conducted by EPA for the SPT site, in order to meet the
requirements under Sections 113(k)(2)(i-v) and 117 of CERCLA.
Dates Activities
March/April EPA community relations (CR) represent-
1985 atives conducted community assessment
interviews with interested community
members in the Selma area.
July 1985 EPA distributed a fact sheet announc-
ing the commencement of RI/FS work,
and describing the RI/FS activities
to the community.
July 1985 EPA held a community meeting in Selma
to explain RI/FS activities that EPA
was undertaking and to respond to the
community's questions and concerns.
-------
-9-
January 1986
March 1986
May 1986
July 1987
April 1988
June 1988
June 22, 1988
September 1988
EPA finalized the Community Relations
Plan detailing the community concerns
as expressed in the July 1985 community
assessment interviews and communitty
meeting.
EPA distributed a fact sheet describ-
ing the purpose and nature of the
monitoring wells placed in the
Selma area. EPA also distributed a
Spanish translation of this fact
sheet.
EPA Community Relations Coordinator
met informally with community members
to listen to their concerns and to
explain current site activities.
EPA distributed well sampling results
to interested community members.
EPA distributed a fact sheet detailing
the results of the Rl.
EPA distributed a fact sheet explain-
ing the contents of the FS Report and
announcing the upcoming public comment
period and community meeting.
EPA held a community meeting to explain
the FS Report and to receive public
comment on EPA's Proposed Plan for
addressing the soil and groundwater
contamination at the SPT site.
Notice of this ROD, or Final Plan,
will be published and made available
to the public before commencement of
the remedial action.
IV. SITE CHARACTERISTICS
The following discussions address contamination problems
for the entire SPT site; there are no operable units
(i.e./ sub-investigations) for this site. All data were
validated by Region 9, EPA, using standard review protocols
and data quality was considered in analysis of the data
and in reaching the decision.
A. Surface And Subsurface Soil Results
A total of 48 surface soil samples were collected during
two rounds of sampling. The samples were collected
from locations where waste was suspected to have been
discharged, from known waste disposal areas, and from
-------
-10-
background locations. The samples were analyzed for a
variety of constituents, including: An initial screening
for Hazardous Substance List (HSL) volatiles, semi-vol-
atiles and metals; hexavalent chromium? individual
phenols; and dibenzodioxin/dibenzofuran (dioxin/furan)
chlorinated tetra through octa homologs. A subsequent
phase to confirm earlier results was performed and
included analysis for isomer specific chlorinated
dioxin/furans and metals. The site-related contaminants
of concern found in surface soils included chromium,
arsenic, copper, dioxin/furan, pentachlorophenol
(PCP), and trichlorophenols (TCP).
A round of subsurface soil samples was collected at 21
boring locations during the RI field program (Figure
3). Samples were generally collected at the following
depths; 1 to 2.5 feet (ft.), 2.5 to 4.0 ft., 4 to 5.5.
ft., 10 to 11.5 ft., 15 to 16.5 ft., and 20 to 21.5
ft. (e.g. to the water table). The samples were
analyzed for individual phenols, chromium, arsenic,
and copper. Selected samples were also analyzed for
the tetra through octa chlorinated dioxin/furan homologs,
without identification of isomers. Chemicals of
concern for the subsurface soils were the same as for
the surface soils.
The soil sampling results identified seven areas where
past practices resulted in levels of contamination
above background concentrations that they warranted
further evaluation. The seven soil contamination
areas are the Waste Sludge Pit, North Unlined Percolation
Ditch (Ditch A), South Unlined Percolation Ditch
(Ditch B), Unlined Waste Disposal Pond, Drainage Area,
Southeast Disposal Area, and Southwest Disposal Area.
Table 1 provides the highest level for each of the
contaminants of concern detected in each area of
concern. Figure 4 identifies the location of each of
the areas. The boundary of each area was based on the
available sampling data and geographical features
associated with each site.
These locations represent areas of concern due to the
elevated levels of site-related contaminants detected
at each of these; sites. For example, high levels of
arsenic, up to 4120 ppm, were detected at the Waste
Sludge Pit. High levels of arsenic were also detected
at the Unlined Waste Disposal Pond and Southeast
Disposal Area. Elevated levels of dioxin/furan contam-
ination, in tetra chlorinated dibenzodioxin (TCDD)
equivalents, were detected at the former Unlined Waste
Disposal Pond and the Southeast Disposal Area.
TCDD equivalents are a means of comparing the levels of
dioxin/furan contamination in various locations. The
toxi'city of a particular dioxin/furan compound is
-------
-11-
Btaine Ave.
200 400 800
P1 WELL BORING LOCATION
SOIL BORING LOCATION
Project No.
123-FS1
Selma Pressure Treating Site
SUBSURFACE SOIL
SAMPLING LOCATIONS
Camp Dresser & McKee
-------
-12-
TABLE
MAXIMUM CONTAMINANT CONCENTRATIONS FOUND IN SOILS
Location
Waste Sludge
Pil (Sample Sites
W04. S34-S38)
- Surface
Unlined Percolation
Ditch A (Sample Sites
SI. 52. S3)
- Surface
1 to 2.5 ft.
2.3 to 4 ft.
-4 to 3.5ft.
- 10(0 11.5ft.
- 15 to 16.3 ft.
- 20 to 21 .5 ft.
Unlined Percolation
Diich B (Sample Sites
S4. S5)
- Surface
1 to 2.5 ft.
- 2.5 to 4 ft.
- 4 to 5.3 ft.
10 to 11. 5 ft.
IS to 16.5 ft.
- :o to 21.5 ft.
Unlined Wane
Disposal Pond (Sample
siies W03. S29 - S33)
- Surface
Southwest
Disposal Area
(Sample site S7)
- Surface
- 1 to 2.5 ft.
- 2.S to 4 ft.
- 4 to 5.J ft.
- 10 to 11.5 ft.
- IS to 16.3 ft.
20 to 21. 5 ft.
Arsenic
mg/kg
4120
55
ND
22
23
3.2
3.5
ND
ND
3.7
12
63
5.3
ND
ND
8SO
21
31
25
28
9.9
17
8 It
Chromium
mg/kg
3910
196
13
9.7
9
8
11
12
12
15
23
19
11
13
12
879
24
31
15
11
S.9
6.7
7
Copper
mg/kg
1870
121
14
9.6
10
7.3
12
18
17
11
10
12
18
8.3
12
553
9
5.6
ND
ND
6.3
3.1
ND
PCP
Ig/kg
11000
1100
32
34.9
363
21.1
ND
43
ND
ND
231
340
11.4
26
ND
460.000
ND
ND
ND
ND
ND
ND
234
Total1
TCP
*g/kg
R
R
277
4.9
14
80
ND
38
ND
10
ND
ND
13
ND
41
R
ND
3
ND
ND
ND
ND
8.0
Total1
Dioxins
ng/g
283.8
130.2
63.2
32.9
40.3
2.5
NS
1.0
7
0.9
0.8
12.5
0.2
NS
ND
1228.7
1233.7
621.3
21.1
2.64
1.7
NS
0.1
Total1 TCDD2
Furans EQUV
ng/g ng/g
36.6 .29
40.1 .31
11.5
2.7
10.1
0.48
NS
0.18
2.5 .01
ND
Q.I
2.5
ND
NS
ND
634 5.65
361.9 .29
119.7
0.7
ND
ND
NS
ND
Total
TCDD
ng/g
ND
ND
ND
ND
ND
ND
NS
ND
ND
ND
ND
ND
ND
NS
ND
ND
ND
ND
ND
ND
ND
NS
ND
Total
TCDF
ng/g
ND
ND
ND
ND
ND
ND
NS
ND
ND
ND
ND
ND
ND
NS
ND
ND
0.12
0.19
ND
ND
ND
NS
ND
Total
PeCDD
"g/g
ND
ND
ND
ND
ND
ND
NS
ND
ND
ND
ND
ND
ND
NS
ND
ND
ND
ND
ND
ND
ND
NS
ND
Total
PeCDF
ng/g
ND
0.7
0.05
ND
ND
ND
NS
ND
ND
ND
ND
ND
ND
NS
ND
11.9
2.8
1.0
ND
ND
ND
NS
ND
Total
HxCDD
ng/g
3.4
3.4
0.71
0.21
0.85
NA
NS
ND
ND
ND
ND
ND
ND
NS
ND
117
12.7
7.3
ND
ND
ND
NS
ND
Total
IUCDF
ng/g
6.8
5.4
1.7
1.1
1.3
0.061
NS
ND
ND
ND
0.21
t.:x
NA
NS
ND
232
64 7
246
0.11
ND
ND
NS
ND
N/A Not Available R: Data Rejected during data validation TCDD: Tetrachlorodibenzo-n-dioxini
ND Not Detected TCDD EQUV: TCDD equivalents
NS Not Sampled TCDF: Telrachlorodibenzorurans
2 Total diotin/Curan analysis includes Tetra through Octa homologs. of which the Octa nomolog Is considered innocuous.
TCDD Equiv. are based on both the isomer specific and homolog data.
PeCDF: Pemachlorodlhenzolurins
HxCDD: Hexachlorodibenzo-p-dloilns
HxCDF: Hexachlorodibenzofuran
PeCDD: Pentachlorodibenzo-p-Oioiins
-------
-13-
TABLE 1 MAXIMUM CONTAMINANT CONCENTRATIONS FOUND IN SOILS (continued)
Location
Drainage
Arei (Sample site S9)
Surface
- 1 to 2.5 ft.
- 2,5 to 4 ft.
- 4 to 5.5 ft.
- 10 to 11.5ft.
- 15 to 16.5 ft.
- 20 to 21. 5 ft.
Arsenic
rag/kg
12.2
5.0
14.0
13.0
2.7
R
1.4
Chromium
mg/kg
25
21
14
10
ND
ND
7.1
Copper
at/kg
15
7.7
17
12
9.2
7.4
13
PCP
*g/kg
ND
ND
ND
ND
ND
ND
ND
Total1
TCP
PE/kg
ND
ND
ND
ND
ND
ND
ND
TotaJ1
Dioxins
ng/g
2S.3
0.5
13.2
11.4
0.6
NS
0.3
Total1
Furans
ng/g
6.8
O.I
2.0
.77
ND
NS
ND
TCDD2
EQUV
ng/g
.03
Total
TCDD
ng/g
ND
ND
ND
ND
ND
NS
ND
Total
TCDF
ng/g
ND
ND
ND
ND
ND
NS
ND
Total
PeCDD
"R/g
ND
ND
ND
ND
ND
NS
ND
Total
PeCDF
ng/g
ND
ND
ND
ND
ND
NS
ND
Total
HxCDD
ng/g
0.38
ND
0.052
ND
ND
NS
ND
Total
IUCDF
"8/g
0.64
ND
0.16
ND
ND
NS
ND
Southeast
Disposal Area (Sample
sites W05. S39 - S44)
Surface
467
390
422
200.000
92
2316.5
2214.2
1.62
ND
ND
ND
S.2
45
R6.2
N/A Not Available R: Data Rejected during data validation TCDD: Teiracnlorodibcnio-n-dionins
ND Not Delected TCDD EQUV: TCDD equivalents
fS Not Sampled TCDF: Tetrachlorodihen/ofurans
2 Total dionin/luran analysis includes Tetra through Octa homologs, of which the Ocla hornolog is considered innocuous
TCDD Equiv. are hasixi on hoth the isomer specific and homolog data.
PeCDF: Penlachlorodibenzol'urans
HxCDD: Hcxachlorodihcnro-n-dioxins
HxCDF: HenachlorcxJiben/oturan
PeCDD: Pcmachlorodibcruop Jionns
-------
Selma Pressure Treating S
EXTENT OF
SOIL CONTAMINATION
-------
-15-
dependent upon the degree of chlorination at the 2,3,7,8,
position. The exception to this is the" octa chlorinated
dioxin/furan homologs, which are considered innocuous.
The remaining tetra through hepta isomers have various
degrees of toxicity. In order to assess the potential
toxicity associated with the dioxin data, each sample
was evaluated with respect to 2,3,7,8 TCDD equivalents.
This involves converting each dioxin/furan homolog
into TCDD equivalents based on the EPA approved method-
ology using Toxicity Equivalent Factors (TEF).
Due to the lack of vertical extent data in source areas,
an estimate of vertical extent of contamination was
made to calculate volumes of soil requiring cleanup.
The metal contamination in the soil was assumed to
extend to a depth of 20 feet, which corresponds to the
approximate depth of the water table. This assumption
is based on the results of the groundwater sampling,
which show elevated levels of chromium in the shallow
portions of the aquifer. Dioxin/furan contamination
is assumed to extend to 10 feet in depth based on
available subsurface sampling results from various
boring locations, which indicate that dioxin/furan
contamination reaches permissible levels within the
first 10 feet. This is evident from Table 1 which
indicates that dioxin was detected in trace levels in
only one soil sample taken from below 10 feet. Additional
soil borings will be collected during RD/RA to refine
this information on vertical extent of contamination.
The site-related surface and subsurface soil contaminants
have variable mobilities in the environment. For
example, dioxin/furan compounds have very low solubilities
and are extremely immobile in the soil. Copper is
also not very mobile in the environment due to its
strong affinity for clays, hydrous metal oxides, and
soil organic matter. Trivalent chromium has similar
sorption characteristics to copper, and as such, tends
not to be very mobile. Hexavalent chromium is very
soluble and highly mobile in the environment. Furthermore,
hexavalent chromium is not easily sorbed on the soil.
However, hexavalent chromium is only stable under
oxidizing conditions and will form trivalent chromium
in a reducing environment. In regard to PCP and
arsenic, these compounds can be relatively mobile
under high pH environments. However, these compounds
appear to be relatively immobile at the SPT site due
to the general lack of observed levels in the groundwater.
B. Soil Clean-up Goals and Areas Requiring Remediation
Of the organic contaminants at SPT, the site-specific
risk assessment indicated that dioxin/furan would drive
the clean-up goals. The clean-up goal selected for
dioxin/furan contaminated soil is 1.0 ng/g (ppb), in
-------
-16-
TCDD equivalents. This clean-up goal is-based on a
TCDD risk study performed by Kimbrough, et al. (1984)
of the Centers For Disease Control (CDC). This study
is the basis for EPA policy and clean-up goals at
Superfund sites where there is dioxin contamination.
The 1 ppb goal is for areas where potential residential
or agricultural uses could occur. While the SPT site
is currently used for industrial purposes, the 1 ppb
goal was selected due to the proximity of residences
and agricultural activities to the site.
The heavy metals of concern at SPT are arsenic/ chromium/
and copper. Based on the health risk assessment, the
metals clean-up goals were driven by arsenic. However,
the primary basis for the metals clean-up goals will
be the protection of groundwater. The selected 50 ppm
arsenic goal assumes solubility and attenuation factors
which are being verified by "collecting more data.
During remedial design (RD), data to evaluate the solu-
bility of the soil contaminants and establish a site-
specific attentation factor may indicate that both the
arsenic and chromium clean-up goals need to be modified
in order to provide adequate protection of the groundwater,
A modification in the clean-up goals could result in a
change in the volume of soil requiring remediation.
The 50 ppm arsenic goal is protective of all direct
contact scenarios except new, on-site residential
development. Institutional controls are required to
prevent on-site residential development.
As stated previously, seven areas of contaminated soil
were identified at SPT (see Figure 4). The clean-up
goals indicate that four of these areas require re-
mediation. The four areas proposed for clean-up
are the Waste Sludge Pit, the Unlined Percolation Ditch
A, the Unlined Waste Disposal Pond, and the Southeast
Disposal Area.
Sampling results for three other areas indicate that
contamination levels are below clean-up goals. These
three areas are the Unlined Percolation Ditch B, the
Drainage Area, and the Southwest Disposal Area.
C. Groundwater Results
The hydrogeologic setting for the area consists of
valley-fill sequence due to the deposition of sediments
from the adjacent Sierra-Nevada highlands. The deposi-
tional environment results in discontinuous geologic
units. The exception to the discontinuous nature of the
units is a five to ten foot clay layer located at a
depth *of approximately 55 to 60 feet below ground surface,
which appears to be continuous or semicontinuous
across the site. Additional data will be collected
-------
-17-
during remedial design to verify the continuity of the
clay layer. The groundwater directly underlying the
site is an unconfined aquifer.
Three rounds of groundwater samples were conducted in
the vicinity of the SPT site. The first round of sampling
occurred in April-May 1986 and included several regional
domestic and irrigation wells, as well as five existing
EPA monitoring wells installed by the EPA Environmental
Response Team (ERT). The second round of sampling was
performed in February-March 1987. This round included
the sampling of the five existing EPA monitoring wells
and the ten newly installed plume tracking monitoring
wells. A third round of sampling occurred in July-August
1987 and included all of the monitoring wells and selected
regional wells. The analyses performed for each round
were as follows:
1. First Round, April-May 1986:
Individual phenols (Method 604)
Routine Analytical Services (RAS) Metals
General water quality parameters
2. Second Round, February-March 1987:
Individual phenols (Method 604)
RAS Metals
General water quality parameters
3. Third Round, July-August 1987:
Individual phenols (Method 604) - all wells
Dissolved chromium, arsenic, copper - all wells
Target Compound List (TCL) Volatiles - existing EPA
and plume tracking monitoring wells
TCL Semivolatiles - existing EPA and plume tracking
wells
Dioxin/furan homologs - five existing EPA monitoring
wells
While there are several contaminants at elevated levels
in the soil, chromium was the only contaminant of signi-
ficance detected in the groundwater, due to the relative
immobility of dioxin/furan, arsenic, and copper.
Organics (dioxin/furan and PCP) are being resampled as
part of remedial design related activities, but previously
detected levels are believed to be due to sampling errors.
Sampling results indicate that a chromium contaminated
plume extends downgradient from the site to the southwest
(Figure 5). The southern boundary of this plume appears
to range approximately 1,200 feet south-southwest of
the existing wood treatment facility boundary. The
groundwater contamination is apparently confined to
-------
-18-
Approximate
R-22
(ND.13.0.2.0J)
Boundary of 50 ugll
/soconcentrat/on
Contour for
Chromium
R-24
<4.0,326,,7.0J)
\
2.0.80.5.0J)
P-4S
(ND.NDJ.O)
Approximate Boundary of
Chromium Contaminated Plume
P-6S
ND,7.0,6.0J>
EPA MONITORING WELL LOCATION
EPA PLUME TRACKING WELL LOCATION
(ND NO 4 0) VALUES FOR ARSENIC. CHROMIUM * COPPER
' ' CONCENTRATIONS IN ug/l- July/Augutt. 1967
P-3S
(ND.2.0.5.0)
DATA ESTIMATED
NOT DETECTED
Setma Treating Company Site
GROUNOWATER PLUME
BOUNDARY MAP
Camp Dresser & McKee Inc.
-------
-19-
the shallower portion of the aquifer (to 40'), and
does not currently affect any municipal, private, irri-
gation/ or industrial wells in the vicinity, based
on the sampling results. Contamination was not detected
in the deep monitoring wells at depths of 87-100'.
However, contamination levels in the intermediate portions
(40-60*) of the aquifer have not yet been defined.
The extent of the chromium contaminated plume needs
additional definition to the west and southwest of well
R24. As part of remedial design, two well nests
west and south of R-24 are planned. A well nest will con-
sist of one shallow well (40') and one intermediate
well (601).
Additional definition of the vertical extent of contam-
ination within the groundwater plume is also planned
as part of remedial design. Three intermediate level
wells completed at depths of 60 feet will be paired
with the existing shallow wells in this area.
Additional data will also be collected on the continuity
of the clay layer present at a depth of 55 to 60 feet.
This data will be collected during the monitoring well
installation program described above.
Other monitoring well installation plans include a
shallow monitoring well (40*) downgradient of the South-
east Disposal Area, and an intermediate level monitoring
well and two observation wells in the upgradient
background area. Other groundwater characterization
activities to be conducted as part of remedial
design include:
1. Monthly water level measurements for one year
2. Quarterly water quality sampling for one year
3. Long-term aquifer testing
4. Efforts to locate and sample the original Brown
and Caldwell monitoring wells
Based on evaluation of the data collected from the
above described activities, a decision will be made
regarding the need for any additional characterization.
D. Groundwater Cleanup Goals
The groundwater cleanup goal is the Maximum Contaminant
Level (MCL) established under both the federal and state
Safe Drinking Water Acts. Due to the fact that chromium
was the only contaminant of significance detected in the
groundwater, additive effects were not of concern. There-
fore, it was possible to select an ARAR as a clean-up
goal, rather than a risk assessment driven goal.
-------
-20-
Currently the MCL pertinent to SPT is the 50 ppb level
set for chromium. The federal MCL is proposed for
revision to 100 ppb, however, the state 50 ppb standard
will probably be in effect at the time of remedial
action. The most stringent of the state or federal MCL
in effect at the time of RD/RA will be used. For
analyses in the Feasibility Study and Record of Decision,
the 50 ppb MCL was assumed. The arsenic MCL of 50 ppb,
is also an applicable ARAR for the SPT site. However,
arsenic was detected only at levels well below the
existing or proposed MCL.
The boundary of the groundwater plume exceeding the
chromium clean-up goal is delineated in Figure 5. This
boundary was based on the elevated chromium values
observed in the shallow monitoring and plume tracking
wells. The western extent of contamination was estimated,
based on the observed trend of the plume in other
areas. The extent of contamination in this area will
be further defined during the RD phase, through the
installation of additional monitoring wells, as discussed
in the proceeding section.
The data collected from the deep plume tracking wells
in the site vicinity indicate that the chromium con-
tamination at a depth of 90-120 feet does not exceed
the chromium clean-up goal of 50 ppb. The exact
vertical extent of contamination that exceeds the
clean-up goal in the intermediate portions of the
aquifer will be further defined as part of the RD, as
described in the proceeding section.
V. SUMMARY OF SITE RISKS
A. Chemicals Of Concern
Data collected during the RI were reviewed to select a
subset of chemicals (chemicals of concern) for detailed
evaluation in the risk assessment. Separate subsets were
selected for surface soils, subsurface soils (soil bor-
ings), and groundwater, in order to reflect the different
exposure pathways associated with these different
media.
A comparison of on-site and background levels of metals
in surface soils, reveals that only arsenic, chromium,
and copper appeared at elevated levels above background.
Therefore these site-related chemicals were selected as
chemicals of concern in surface soil, from among the
metals. The organics of concern in the surface soil,
identified in the risk assessment, were phenols, dioxins,
furans, bis(2-ethylhexyl) phthalate, and di-n-butylphth-
alate. An analysis of subsurface soils produces the same
subset of chemicals of concern, except that the phthalates
-------
-21-
were not included. The levels of arsenic and dioxin/furan
contamination in the soil were the only constituents
exceeding the health based clean-up goals.
Groundwater samples were collected from domestic, indus-
trial, municipal, and irrigation wells, and from fifteen
monitoring wells. Site-related chemicals detected were
arsenic, chromium, copper, pentachlorophenol, and two
dioxin congeners. Based on considerations of toxicity,
concentration, and relations to site activities, arsenic,
chromium, copper, and the dioxins were selected as chem-
icals of concern. However, only chromium exceeded the
clean-up goals in groundwater.
B. Exposure Pathways
Potential human exposure pathways at the SPT site include
exposure to contaminated groundwater, exposure via direct
contact with contaminated soil (including incidental
ingestion), and inhalation of contaminated dust. Based
on data from existing private and municipal wells, risks
associated with current use of groundwater in the vicinity
of the site were evaluated. Using estimates based on
data from monitoring wells and groundwater modeling,
potential future risks associated with use of local
groundwater as a potable supply were also evaluated. For
soil, the EA evaluated exposure of individuals working at
the site or in the vicinity of the site, local residents,
and trespassers. Direct contact (dermal absorption or
inadvertent ingestion) and inhalation were the exposure
routes used. A number of scenarios involving these types
of exposure were examined. Finally, a number of scenarios
examining the potential exposure of off-site receptors to
contaminants present in windborne dust also were evaluated
using an air dispersion model.
C. Toxicity Of Chemicals Of Concern
Both the carcinogenic and noncarcinogenic effects of
chemicals of concern used in the EA analysis are presented
below. Exposure to arsenic has been associated with an
increased incidence of cancer in humans. Chromium has
been associated with an increased incidence of lung
cancer in humans exposed via inhalation, but has not been
associated with an increased incidence of cancer when
exposure occurs via ingestion. Bis(2-ethylehexyl)phthalate
and 2,4,6 trichlorophenol are classified as probable
human carcinogens based on evidence from animal carcino-
genicity bioassays. Certain dioxins and furans are
considered to be carcinogenic by EPA and are also toxic to
the reproductive system and the immune system.
Exposure to chromium via ingestion is associated with
non-carcinogenic toxcicity, including decreased water
consumption, and at higher levels, gastrointestinal
-------
-22-
disturbances, liver damage, kidney damage-, internal
hemorrage, dermatitis, and respiratory problems. Many of
these effects are thought to be due to chromium VI, not
to chromium III. Exposure to copper, chlorophenol,
cresols, di-n-butylphthalate, 2,4-dichlorophenol,
2,4-dinitrophenol, 2- and 4-nitrophenol, pentachloro-
phenol, and phenol have been associated with a variety
of systemic, noncarcinogenic effects in humans or
experimental animals.
Risk Characterization
A quantitative assessment of potential risks posed by
contaminants in the vicinity of the SPT site was performed.
The potential for endangerment of human health under a
number of current-use and future-use exposure scenarios
was evaluated. For each exposure scenario evaluated,
two exposure cases, an average and a plausible maximum
case, were considered. For the average exposure case,
mean concentrations are used together with what are
considered to be the most likely (though conservative)
exposure conditions. For the plausible maximum case,
the highest measured concentrations are used, together
with high estimates of the range of potential exposure
parameters relating to frequency and duration of exposure
and quantity of contaminated media contact.
To summarize the risk assessment, carcinogenic risks at
SPT may be associated with exposure to surface soil con-
taminants and airborne particulates under current use
scenarios. Under future use scenarios, exposure to
groundwater contamination may pose both a carcinogenic and
noncarcinogenic risk. Risk results for both the current-
use and future-use scenarios are discussed below. The
risk numbers are presented for carcinogenic risks
greater than 1 x 10~*> or where the Chronic Daily Intake
(GDI) exceeded the Reference Dose (RfD) for noncarcino-
genic risks. Generally, at SPT these risks are associated
with the plausible maximum scenario, rather than the
average case.
1. Current-use scenarios: Under current-use scenarios,
exposure of workers and residents to surface soil
contaminants in the adjacent vineyard, through
dermal adsorption and incidental ingestion, and
inhalation were considered a carcinogenic risk.
The plausible maximum risk associated primarily
with exposure to arsenic and dioxin/furans was 3 x
10~4, or the risk of three excess cancer cases dur-
ing a lifetime exposure of 10,000 individuals.
The plausible maximum cancer risk from exposure of
trespassers to surface soil contaminants at the
wood treating facility was 2 x 10~5. For workers,
the average risk was 6 x 10~6 and the plausible
-------
-23-
maxiraura risk was risk was 4 x 10~3. Again this
risk is associated primarily with exposure to
arsenic and dioxin/furans.
The plausible maximum risks due to inhalation of
contaminated dust are associated primarily with
exposure to arsenic and chromium. The risk ranges
from 1 x 10~5 to 5 x 10~6 for locations 250 meters
north and south of the site and 500 meters southeast
of the site.
Under current-use conditions/ groundwater as a
potable supply is not expected to be a potential
health concern, since the GDI is less than the RfD.
This is based on exposure to chromium, which is a
noncarcinogen by ingestion. The reason the current-
use scenario has no risk is that no drinking water
wells are currently within the groundwater plume
boundaries. Institutional controls are needed to
ensure that no wells are drilled into the contaminated
area for drinking water purposes, until remediation
is completed.
Future-use Scenarios; Under future use conditions,
use of the shallow groundwater as a potable supply
may be a potential health concern under the plausible
maximum scenario, where the GDI levels for chromium
could be 49 times greater than the RfD.
For the deep groundwater, risk assessment based on
a mass balance model indicated that the GDIs for
several of the noncarcinogenic contaminants of
concern could exceed their corresponding RfDs under both
the average and plausible maximum scenarios. This
is due to the potential for future leaching of
contaminants, such as chromium, out of the soil
into the groundwater.
Under the mass balance model, excess cancer risks
associated with exposure to carcinogenic contaminants
(primarily background arsenic) was estimated to be 3 x
10~2. However, arsenic is not expected to be highly
mobile at SPT, based on observed levels in groundwater.
The mixing model used to derive the risk number did
not account for attenuation of contaminants in the
environment and represents a very conservative estimate
of the potential future risk associated with groundwater
use. Because of this, arsenic was not retained as a
chemical of concern in the formulation of groundwater
remediation alternatives in the FS.
Under future use scenarios, direct contact with soil
contaminants or inhalation of contaminated particulates
-------
-24-
over relatively short periods of time by on-site
construction workers, are not expected to be a
potential health concern. This is the case for
exposed individuals under either average or plausible
maximum cases.
E. Analytical Methods Used
The Endangerment Assessment for the SPT site generally
followed the guidelines established by EPA for risk
assessments under CERCLA (EPA 1985a, 1986a) and for
health risk assessments in general (EPA 1986b,c,d).
The purpose of the assessment was to evaluate the No
Action Alternative. The assessment was based on data
generated under the EPA contract laboratory program
(CLP).
VI. DOCUMENTATION OF SIGNIFICANT CHANGES, Section 117(b)&(c)
of CERCLA
The preferred alternative in the Proposed Plan is the same
as the remedy selected in this ROD: Soil fixation with a
RCRA cap and conventional groundwater treatment. No signif-
icant changes are proposed at this time. Additional data
collection activities that will occur as part of remedial
design could impact information contained in the ROD.
VII. DESCRIPTION OF ALTERNATIVES
A. Alternative 1 - No Action
This alternative involves taking no action to treat,
contain, or remove the contaminated groundwater and soil.
Multi-media monitoring would be performed every five
years to support a reassessment of the No Action Alterna-
tive. The costs for this alternative are as follows:
Capital cost $18,000
Operation and maintenance (OSM) cost (annual) $22,000
Present worth (life of project at 8% dis-
count and 4% inflation rates) $90,000
B. Alternative 2 - RCRA Cap with Slurry Wall
Alternative 2 is a containment alternative. The function
of the multi-layer RCRA Cap is to prevent direct contact
with soil by humans and wildlife, and to minimize the
potential for airborne contamination. In addition, the
low permeability Cap reduces infiltration and leaching
of contaminants from the soil into the groundwater. The
Cap would be constructed over the areas of contam-
inated soil that exceed the cleanup goals. Approximately
33,300 square feet of Cap would be required to cover
these areas, based on the current clean-up goals.
The Cap would meet the RCRA closure requirements under
-------
-25-
40 C.F.R. §264, Subparts F, G and N. An ^example of Cap
construction according to EPA closure guidance would
be:
1. A 2 foot clay layer with hydraulic conductivity
no greater than 1 x 10"^ cm/sec.
2. A minimum 20 mil High Density Polyethylene (HOPE)
geomembrane.
3. A one-foot sand layer with a hydraulic conductivity
of 1 x 10~3 cm/sec and filter fabric.
4. A two foot top soil layer.
Capping does not eliminate the leaching of contaminants
from the untreated waste left on-site. Fluctuating
groundwater levels may cause groundwater contact with
contaminated soils. This may result in additional
contamination at levels above the MCL, particularly for
chromium.
The groundwater component of this alternative is to
install a slurry wall to isolate the contaminated
groundwater from the uncontaminated portion of the
aquifer. A 1,375 foot long wall would be keyed into a
clay layer at a depth of 55 feet. Approximately 75
million gallons of contaminaated groundwater is estimated
to need containment. Extraction wells would be placed
inside the slurry wall to maintain the hydraulic gradient
toward the contaminated groundwater being contained.
Monitoring wells would be located downgradient and
outside the slurry wall in order to evaluate the
effectiveness of the wall over time. The risks of
leaving contaminated groundwater in the aquifer would
be potential exposure of users to water that does not
meet the drinking water standards. Therefore, institu-
tional controls to prevent such use are required.
The major limitation associated with the slurry wall
is that the clay layer proposed for its base may not
be thick or continuous enough to support the wall.
Additional investigation of this, clay layer would be
needed to support this alternative.
The aquifer in the Selma area is currently classified
under EPA's Groundwater Protection Strategy, as a Class
II A aquifer, which is currently used for drinking
water and other beneficial uses. Also, the Fresno area
has a designated Sole Source Aquifer under the Safe
Drinking Water Act, 42 U.S.C. S1424(e). Alternative 2
would not be consistent with protection of this groundwater
resource, due to the continued exceedences of the MCL
for chromium and the potential for continued leaching
of chromium or other constituents from the soil.
-------
-26-
Under Alternative 2, implementation requirements include
obtaining permission for use of private property during
Cap and slurry wall construction. The slurry wall
would require permanent easements or private property
acquisition along its alignment. Off-site treatment and
disposal options for the extracted groundwater would need
to be evaluated.
Long-term institutional controls would be implemented
to prevent access by unathorized persons to the capped
areas, including fencing, signs and other land use
restrictions. Long-term access to capped areas, extraction
wells, and monitoring wells would be needed by government
officials or representatives to ensure O&M activities
could occur. Finally, long-term institutional controls
would be needed to prevent the use of the contaminated
portions of the aquifer as a drinking water supply.
The implementation timeframe for Alternative 2 would be
approximately two months for RCRA Cap construction
and seven months for slurry wall construction, after
property access agreements have been obtained.
Costs for Alternative 2 are as follows:
Capital: $2,180,000
O&M: $40,000
Present worth: $2,390,000
C. Alternative 3 - Soil Fixation with a RCRA Cap and
Conventional Groundwater Treatment
For soils, Alternative 3 has both treatment and contain-
ment components. The function of soil fixation, as
treatment, is to create a monolithic soil matrix which
inhibits leaching, using a stabilization and solidifi-
cation process. The RCRA Cap, placed on top of the
fixed soils would provide additional protection from
surface disturbance and surface water infiltration. The
waste to be treated is contained in the areas where the
soil constituents exceed cleanup goals. Also, under
this alternative/ six dry wells will be evaluated and
abandoned, as appropriate.
The arsenic and chromium contamination is considered a
RCRA characteristic waste under 40 C.F.R. §261.24. The
dioxin and PCP waste is considered a RCRA K001 listed
waste under 40 C.F.R. §261.32. Once excavated, substantive
RCRA standards for treatment, storage and disposal of
these wastes under 40 C.F.R. §264 apply. In addition,
disposal of K001 waste is regulated under 40 C.F.R.
§268, Land Disposal Restrictions, since placement has
occurred. The volume of contaminated soils requiring
treatment total approximately 16,100 cubic yards of
-------
-27-
raaterial. Volume estimates will be further refined
during remedial design/ and should be considered
estimates here.
The typical on-site fixation operation includes a batch
plant for mixing the fixative agent (cement/ silicate
materials, and additives)/ and conventional construction
equipment for excavating and backfilling the soil. The
batch plant and staging area for temporary storage of
contaminated soils is proposed for a 1.5 acre area in
the northwest corner of the SPT site. The staging area
will comply with RCRA regulations under 40 C.F.R. §264,
Subpart L - Waste Piles/ calling for temporary double
synthetic liners and a double leachate collection
system. The temporary waste and storage facilities
will also need to comply with the construction standards
for Class I waste piles in Title 23, Subchapter 15,
California Code of Regulations (CCR). Cap construction
will be as outlined for Alternative 2, and will meet
the same RCRA applicable or relevant and appropriate
requirements (ARARS).
The fixed soil will meet the leachablity requirements
for the appropriate site-specific constituents under
RCRA. The maximum concentration of arsenic and chromium
characteristic wastes, using EP toxicity, is 5 mg/1
under 40 C.F.R. §261.24. It is predicted that fixation
will meet land disposal restriction level under 40
C.F.R. §268, of 37 ppm for PCP, using a total waste
analysis test.
Also, as discussed previously, soils will be tested
during remedial design to determine the soluble fraction
of the contaminants and the attenuation factor. Based
on this testing, treatment goals needed to protect ground-
water will be evaluated by EPA and the RWQCB. The
RWQCB recommends site-specific cleanup goals under the
authority of the Porter Cologne Water Quality Control
Act California Water Code §§13000 et seq.
Under Alternative 3, residual levels of arsenic, dioxin/
furan, chromium, copper, and phenols below the health
risk-based cleanup goals would remain onsite, untreated.
Based on the Endangerment Assessment for SPT it was
determined that these residuals will not pose an unacceptable
risk to public health or the environment. The solubility
testing will ensure that residual levels do not pose a
risk to groundwater.
There is a potential for the future breakdown of the
monolithic soil matrix. To reduce this potential the
fixed soils will be covered with a Cap that meets the
RCRA requirements as described under Alternative 2.
Long-term monitoring will also be performed to meet the
substantive RCRA requirements for closure under 40
C.F.R. §264, Subpart F, G and N.
-------
-28-
For the groundwater component of Alternative 3, a
conventional precipitation, coagulation, and floccu-
lation process is proposed to remove chromium to the
MCL level. Based on the assumption of a 50 ug/1 MCL
and a two dimensional model, the volume of extracted
groundwater requiring treatment is estimated at 2.7
billion gallons. This estimate will be further defined
during the remedial design phase of the project, based
on additional aquifer testing and monitoring well
installation.
Based on the estimate discussed above and the distribu-
tion of the plume, approximately 25, 6-inch diameter
extraction wells, 50 feet deep will be pumped at a
cumulative total of 1,040 gallons per minute for five
years. This assumes a treatment plant operating 24
hours a day, seven days a week, with an online availablity
of approximately 95%. The five year timeframe is based
on several assumptions regarding estimates of extent of
contamination, the number of extraction and injection
wells, and the .volume of groundwater requiring treatment.
Specific timeframes will be further defined as part of
RD. A range of 5-10 years may be more realistic,
depending on the results of data collected during RD.
The treatment facility will consist of an influent
storage tank/ a rapid mix unit, a slow mix unit, a sedi-
mentation tank, a filter, a treated effluent storage
area, and associated piping, valves, and pumps. This
facility proposed for location in the vineyard south of
the wood treating facility, will occupy approximately
1/2 acre.
Based on satisfactory treatment and testing of the ground-
water, either reinjection or off-site disposal will occur.
If reinjection is appropriate, approximately 35, 4-inch
diameter recharge wells will also be distributed throughout
the aquifer.
The treatment level to be achieved is the more stringent
of the federal or state Safe Drinking Water Act Maximum
Contaminant Levels. Currently this level is 50 ppb,
under both federal and state law. Residual untreated
groundwater would not exceed the MCL. Residual treated
groundwater would either be reinjected or disposed of
off-site. For reinjection, substantive requirements of
the Safe Drinking Water Act 42 U.S.C. §§1421-1422,
40 C.F.R. §5144-147, would be met. For off-site disposal,
the RWQCB would establish discharge limits consistent
with requirements under the National Pollutant Discharge
Elimination System (NPDES) program. The reinjection
of treated groundwater will also be regulated by substantive
RWQCB waste discharge requirements to provide protection
of the beneficial uses of the underlying groundwater.
-------
-29-
The sludge generated from the treatment facility will
be dried in lagoons on two acres adjacent to the treatment
facility. The sludge will be disposed of at an approved
off-site RCRA facility or municipal landfill, depending
on sampling results. The sludge lagoons will be con-
structed to RCRA standards as set forth in 40 C.F.R. §264 -
Subpart K - Surface Impoundments, which require two or
more liners and a leachate collection system. Synthetic
liners are proposed for use at SPT. The sludge lagoons
will also need to meet the construction criteria in
Title .23, Subchapter 15 of the CCR, regulated by the
RWQCB. Other options, for sludge drying, such as
mechanical methods, will be considered during the
design phase.
Regarding implementation requirements for soil remediation
activities under Alternative 3, equipment and materials
for Cap construction are readily available. Treatability
testing is required for soil fixation, and is currently
being performed. There are numerous commercial enterprises
involved in developing and marketing fixation technology.
Sixteen companies were identified in a vendor survey as
capable of providing expertise in treating metals and
organics with solidification and stabilization processes.
Access to private property will be needed for the batch
plant and staging areas.
Short-term worker protection during soil excavation
will be required, consistent with federal and California
Occupational Safety and Health Act (OSHA and Cal OSHA)
standards. EPA currently has federal-lead jurisdication
for worker protection at wood treating facilities.
However, EPA has adopted OSHA standards for use at
these sites. Excavation, storage, and fixation of soil
are also subject to Fresno Air Pollution Control District
(APCD) Rules 210.1, 404, 405, and 418. Discharges
during remediation could include: (1) fugitive dust con-
taining toxic metals and toxic organics, and (2) volatile
toxic organics. Requirements of the Clean Air Act, 42
U.S.C. S7401 et seq, are incorporated into APCD Rules,
per Section 110 of the Clean Air Act.
For the groundwater component, implementation requirements
include disposal of treatment residuals, utility require-
ments, access to private property for the treatment
plant and sludge lagoons, treatability studies for waste
stream characteristics, and disposal of treated water.
Significant implementation obstacles are not foreseen.
The main uncertainty regarding Alternative 3 is the
implementability of soil fixation based on treatability
testing. If this test is not successful, it will be
necessary to select a different alternative to remediate
SPT site soils.
-------
-30-
The groundwater classification is Class II A, and
implementation of Alternative 3 would be consistent
with maintaining the use of the aquifer for drinking
water and other purposes.
Short-term institutional controls include limiting
access to the staging area, treatment areas, and sludge
drying beds,' through use of fencing, signs and security.
Until remediation of groundwater is achieved, institu-
tional controls over the use of the contaminated portions
of the aquifer will be required. Long-term institutional
controls include access restrictions to capped and
fixed areas, and long-term access for monitoring and
maintenance activities.
The implementation timeframe for Alternative 3 is
approximately 12-18 months for the soil component and
5-10 years for groundwater treatment.
Costs associated with Alternative 3 are estimated as
follows:
Capital: $ 6,500,000
O&M: $ 1,300,000
Present Worth: $11,280,000
D. Alternative 4 - On-site Rotary Kiln with Off-site
DjLsjposal and Conventional Groundwater Treatment
This alternative has both treatment and containment
(disposal) components. The groundwater components are
the same as described in Alternative 3 and will not be
discussed further here. The soil treatment component
applies to the organic constituents in the soil. An
on-site rotary kiln would be used to incinerate dioxin/
furan and pentachlorophenol wastes totalling 7800 cubic
yards. Included with the organic wastes are metal
constituents that would not be destroyed during inciner-
ation. In addition, there is another 8300 cubic yards
of metals contaminated soil with no organic contamination.
All of the soils, treated and untreated (a total of
16,100 cubic yards), would be disposed of at an off-site
RCRA facility. The SPT wastes containing pentachlorophenol
would require treatment (e.g., incineration) prior to
disposal to meet the present RCRA Best Demonstrated
Available Technology (BDAT) requirements of 37 ppm,
under 40 C.F.R. §268. The untreated arsenic and chromium
contaminated wastes are RCRA characteristic wastes and
therefore require disposal at an approved RCRA Class I
facility.
The mobile unit assumed for SPT is rated at 15 million
BTU/hour and treats 4.50 tons/hour of dry solids.
The primary (i.e., rotary kiln) and secondary (i.e.,
afterburner) combustion chambers are generally mounted
-------
-31-
on concrete slabs. Approximately .5 acres is expected
to be required for stockpiling excavated soil, locating
feed handling and preparation equipment, and temporary
storage of decontaminated soil. Sufficient area for
processing exists on the storage yard being used by
the present wood treating operation.
For organics, treatment levels achieved would be the
BDAT treatment level requirements for PCP of 37 ppm
and the 1 ppb clean-up goal for dioxin/furan contamination.
For the incinerator, 99.99% destruction and removal
efficiency (DRB) is required under 40 C.F.R. S264,
Subpart 0, for the principal organic hazardous constituents
(POHCs). The metals would remain untreated, and would
either be captured in the air pollution control equipment
or remain in the incinerated soil residuals.
If BDAT for metals under 40 C.F.R. §268 is in effect at
the time of project implementation, then these levels
would need to be met as well. For this ROD it is
assumed that the incinerator soil residuals would
require disposal at a RCRA Class I facility due to the
metals content of the residue.
Under the California Air Resources Act, California
Health and Safety Code §39650 et seq, the Air Pollution
Control District (APCD) will set emission limits for
discharges associated with use of the incinerator under
APCD Rule 210.1, New Source Review. Rules 404, 405, 418
and 417 also apply to excavation and incinerator activ-
ities. Discharges associated with soil excavation may
consist of: (1) fugitive dust containing toxic metals
and/or toxic organics, and (2) volatile toxic organics.
Compliance with APCD Rules includes Clean Air Act
requirements.
Implementation requirements include access to a mobile
rotary kiln, of which there may be a limited supply.
Acceptance of SPT wastes at an off-site RCRA facility
would be determined based on waste characteristics and
BDAT requirements in effect at the time of waste disposal.
Access to private property is required for the inciner-
ator, groundwater treatment systems, and monitoring
well installation activities. Pilot work would be
necessary to aid in addressing materials handling
requirements and to assess air .emissions.
Alternative 4 would be consistent with the area's Class
II A aquifer classification. The contaminated groundwater
would be treated and contaminated soils would be removed.
The removal of the contaminated soil would prevent the
possibility of continuing migration of the contaminants
to the groundwater. As stated previously, soil clean-up
goals will be evaluated after solubility testing to
ensure protection of groundwater quality.
-------
-32-
Institutional controls include short-term access restric-
tions to the soil and groundwater treatment areas/ and
restrictions over the use of the contaminated portions
of the aquifer for drinking water purposes. Long-term
institutional controls are not needed for this alternative.
The soils remediation implementation timeframe for
Alternative 4 would be 7-10 months at an incinerator
unit operating 24 hours a day, seven days a week, with
online availability of 80%. An additional 1-2 months
would be required to demobilize equipment. Groundwater
treatment is estimated to take 5-10 years.
Costs estimated for Alternative 4 include:
Capital: $15,630,000
O&M: $1,290,000
Present worth: $20,360,000
VIII. SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
A. Overall Protection of Human Health and the Environment
1. No Action; No protection is provided, although
monitoring would provide a warning indicator of
contaminant transport.
2. RCRA Cap with Slurry Wall; Partial protection is
provided, with ongoing maintenance. The migration
of contaminated groundwater is restricted from
reaching uncontaminated portions of the aquifer.
Direct contact with soils and generation of contam-
inated airborne dust is prevented. The Cap also
limits infiltration of surface water and contaminant
mobility. Institutional controls are necessary to
prevent the use of contaminated groundwater exceeding
primary drinking water standards. Continued leaching
of capped soils due to groundwater fluctuations
could exacerbate the chromium contamination problem.
3. Soil Fixation with RCRA Cap and Conventional Ground-
water Treatment; For soil, protection is provided
with ongoing -maintenance. Cap protection features
are the same as for Alternative 2. Addition of the
fixative agent greatly reduces continued leaching
of contaminants to groundwater, protecting potable
water supplies from a continuing source of contamina-
tion. Groundwater treatment provides complete
protection to the MCL cleanup level.
4. On-site Rotary Kiln and Off-site Disposal with
Conventional Groundwater Treatment; For soil,
complete protection is provided on-site. No contam-
inants exceeding the cleanup goals remain at SPT.
Careful short-term incinerator operation would be
-------
-33-
required to assure that significant adverse air
quality impacts do not occur. For groundwater, the
same complete level of protection is provided as
for Alternative 3.
B. Compliance with ARARS
1. Alternative 1: Does not comply with MCLs for ground-
water. No action would be taken to meet ARARS.
2. Alternative 2; Does not comply with MCL for chromium
or Porter Cologne Water Quality Act cleanup goals
for soils (a requirement "to be considered," rather
than an ARAR). Would comply with RCRA requirements
under 40 C.F.R. §264, Subparts F, G, and N.
3. Alternative 3; Will comply with all ARARS, including
MCLs, RCRA BDAT for K001 listed waste, and RCRA
closure requirements.
4. Alternative 4; Would comply with all ARARS identified
at this stage, including MCLs, RCRA BDAT for K001
listed waste, and RCRA requirements for off-site dis-
posal of waste. .
C. Long-term Effectiveness and Permanence
1. Alternative 1; Not a permanent solution.
2. Alternative 2; Not a permanent solution. Long-term
monitoring and maintenance activities are associated
with the Cap. Groundwater is not treated. Long-
term institutional controls would be required to
ensure that drinking water wells are not located in
the contaminated portions of the aquifer.
3. Alternative 3; For soil, full permanence cannot be
assured due to limited experience with the fixation
technology. Long-term maintenance and monitoring
is required. Depending on the monitoring results,
additional work could be required in the future if
the monolithic soil matrix breaks down. For ground-
water, a permanent solution.
4. Alternative 4; For soil, a permanent solution for
organics (dioxin/furans and PCP); but not permanent
for metals. Off-site disposal requires long-term
O&M at the RCRA facility. For groundwater, a
permanent solution.
D. Reduction in Toxicity, Mobility and Volume (TMV)
1. Alternative 1; Does not reduce TMV.
2. Alternative 2: Reduces mobility but not toxicity or
volume.
-------
-34-
3. Alternative 3; For soil, mobility significantly
reduced, toxicity is not reduced, and volume is in-
creased due to the addition of the fixative agent.
For groundwater, TMV reduced.
4. Alternative 4; For soil, near complete reduction of
toxicity and mobility for organics. For metals,
reduces mobility only by removing contaminants from
the site and containing them in a Class I RCRA facil-
ity. For groundwater, TMV reduced.
E. Short-term Effectiveness
1. Alternative It There would be no short-term impacts.
2. Alternative 2t Short-term impacts to workers
associated with slurry wall and Cap construction
would be minimal.
3. Alternative 3t Short-term exposure to workers during
soil excavation and treatment, and groundwater well
installation could occur. Worker safety precau-
tions and dust suppression needed to protect workers
and others onsite.and in site vicinity.
4. Alternative 4; Short-term impacts would be comparable
to Alternative 3. Differences include short-term
potential for accidental spillage during off-site
transport of wastes and exposure to incinerator
emissions. Air pollution control equipment and
careful transport required in addition to measures
outlined in item 3, above.
F. Implementability
1. Alternative It No implementability factors are
relevant.
2. Alternative 2t The technology for both the RCRA Cap
and slurry wall are readily available. The technical
feasibility of the slurry wall is questionable due
to potential problems with inadequate thickness and
continuity of the clay layer. Access problems assoc-
iated with the slurry wall alignment may also arise.
3. Alternative 3; The RCRA Cap and conventional ground-
water treatment technologies are readily available
and proven. Property access/acquisition problems
may arise for the well installation and treatment
areas. Fixation technology requires site-specific
treatability testing to verify effectiveness prior
to use.
-------
-35-
Alternative 4; Conventional groundwater treatment
issues are the same as under Alternative 3, above.
Use of incinerator requires prior on-site treat-
ability testing in coordination with the local
APCD. Off-site disposal of wastes requires acceptance
by the receiving facility depending on actual waste
characteristics analysis. Regulatory status governing
off-site disposal of land ban wastes may influence
disposal options at time of remedial action.
Estimated Capital, O&M, and Present Worth Cost
CAPITAL
O&M
PRESENT WORTH
Alt 1 No Action
Alt 2 Slurry Wall/
RCRA Cap
Alt 3 GW Treatment/
Fixation
Alt 4 GW Treatment/
Rotary-Kiln/
Off-Site Disposal
$18,000
2,180,000
6,500,000
15,630,000
22,000
40,000
1,300,000
1,290,000
90,000
2,390,000
11,280,000
20,360,000
H. State and Community Acceptance
1. Alternative 1; Not acceptable to the state; no
input was received from the community.
2. Alternative 2; Not acceptable to the state due to
potential insufficiency of clay layer to key slurry
wall into and because chromium remaining in soils
under the Cap could leach to groundwater. No
community input received.
3. Alternative 3; Acceptable to the state. Additional
remedial design-related groundwater and soil sampling
and treatability testing will be reviewed by the state
for continued acceptance of remedy. No community
comments received.
4. Alternative 4; State concerned about potential
incinerator emissions-related public perception and
regulatory approval problems. Incinerator pilot
testing and remedial design-related sampling results
would be reviewed by the state. No community
issues raised at this time.
IX. THE SELECTED REMEDY
Alternative 3 - Conventional Water Treatment and Soil Fixation
with a RCRA Cap, has been selected as the remedy for the
SPT site. Remediation of the chromium contaminated groundwater
under this alternative consists of pumping the groundwater
from the aquifer, treating it in an on-site facility utilizing
-------
-36-
a conventional water treatment method, and disposing of the
treated effluent through reinjection into the aquifer, or
off-site, as appropriate.
The soil remediation component of this alternative consists of
excavating the contaminated soil, transporting it to a pro-
cessing plant onsite; "fixing" the soil with cement, silicate
and other bonding agents; and then backfilling and compacting
the fixed material on-site. Fixed areas of soil will then be
covered with a RCRA Cap.
X. THE STATUTORY DETERMINATIONS
A. Protection of Human Health and the Environment
The selected remedy will eliminate risk of exposure to
groundwater contaminated with chromium above MCL levels.
The remedy will eliminate exposure to contaminated soil
that exceeds groundwater and health based cleanup
goals. In the case of soils, the contaminants will not
be removed or destroyed. Long term O&M is required to
ensure that the soil remedy is effective.
Adequate safety precautions will be used during construc-
tion and treatment activities. Therefore, unacceptable
short-term impacts are not expected. Cross media
impacts are also not foreseen associated with this
remedy. Careful attention to drilling techniques will
be paid to ensure that drilling will not contaminate
the deeper, unaffected portions of the aquifer. Cleanup
goals will take into account the potential leaching of
soil contaminants into the groundwater. Careful dust
suppression methods during all remedial activities will
ensure that contaminants are not transmitted into the
air at unacceptable levels during construction. The
RCRA Cap will provide long-term protection agaist trans-
mission of contaminated particulates into the air.
B. Attainment of ARARS
The selected remedy will attain the applicable or relevant
and appropriate requirements determined to date; no
ARARS waiver is necessary. The following are the main
ARARS that have been determined to apply to the remedy:
Statute
Safe Drinking Water Act
42 U.S.C. §300A ejt seq;
40 C.F.R Part 141.
Safe Drinking Water Act
42 U.S.C. §300A e_t seq;
40 C.F.R. Parts 144-147.
Standard
Maximum contaminant levels
for chromium and arsenic
in groundwater.
Underground injection
control requirements for
Class V Wells, including
dry wells.
-------
-37-
Safe Drinking Water Act
42 U.S.C. §1424(e).
Resource Conservation
and Recovery Act
42 U.S.C. §6901 et seq;
40 C.F.R. Parts 257, 261,
262, 263, 264, 265, 268.
California Safe Drinking
Water and Toxic Enforcement
Act. California Health and
Safety Code §252.5 et seq.
California Air Resources
Act. California Health and
Safety Code §39650 et seq.
Porter Cologne Water
Quality Control Act.
California Water Code
§13000 et seq.
California "Superfund"
Law - Hazardous
Substances Account Act/
Hazardous Substances
Cleanup Bond Act.
California Health and Safety
Code §25300 et seq.
California Occupational
Safety and Health Act.
California Laboratory
Code §6300 et seq.
Occupational Safety and
Health Act. 29 U.S.C.
§651 et seq.
Cost-Effectiveness
Prohibits any project with
federal financial assistance
from contaminating a Sole
Source Aquifer.
Practices to be followed by
generators, transporters,
owners and operators of
hazardous waste. Standards
for land disposal of certain
restricted hazardous wastes.
The state MCL for
chromium.
Discharge limits for
activities conducted
during the remedial
action. Includes Clean
Air Act requirements.
Waste discharge requirements,
NPDES discharges, specific
cleanup standards estab-
lished on a site specific
basis.
Substantive requirements
of a Remedial Action Plan
(RAP).
Standards for worker
protection during remed-
iation.
Under 40 C.F.R. §300.38,
OHSA requirements apply to
all activities conducted
under the NCP.
The selected remedy estimated at $11,280,000 is the
least expensive of the remedies that meet the statutory
criteria of protection of public health and the environ-
ment, and attainment of ARARS. For example, alternative
4, Conventional Water Treatment/Incineration and Off-site
Disposal is estimated at $20,360,000; almost double the
selected remedy. Alternative 2, slurry wall/RCRA Cap,
-------
-38-
is much less costly than the selected remedy at an esti-
mated $2,390,000; but would not be protective of public
health or meet ARARs.
D. Utilization of Permanent Solutions Employing Alternative
Technologies to the Maximum Extent Practicable (MEP)
The selected remedy is an appropriate solution for the
site. It will effectively treat groundwater contaminants,
prevent contact with soil contaminants, and prevent leach-
ing of contaminants to the groundwater at levels above
the MCL. The remedy provides protection of public
health, achieves ARARS compliance and is cost-effective.
In comparison, on-site and off-site RCRA disposal options
are more problematic for soils at SPT than the chosen
method of fixation. An on-site RCRA landfill would not
meet RCRA or CCR siting criteria due to the site geology
and presence of a Sole Source Aquifer. Since BDAT was
not established for the dioxin K001 waste, it could con-
ceivably be disposed of off-site, along with the metal
contamination, without treatment. The PCP wastes would
require treatment to the 37 ppm BDAT standard. However,
straight off-site disposal of wastes does not comply
with the intent of CERCLA for remedies that use permanent
solutions and treatment to the maximum extent practicable.
Finally, the regulatory status governing land disposal
of SPT waste is in a state of development. It is not
certain whether RCRA disposal facilities would accept
SPT wastes at the time of remediation; and if so, what
Best Demonstrated Available Technology (BDAT) would be
required (BDAT may be promulgated for arsenic).
In regard to soil treatment methods, fixation and inciner-
ation were the only two that were deemed technically
feasible in the FS screening process. Incineration,
however, treats only the organic contents of the SPT
waste, resulting in untreated metals requiring disposal.
Fixation has been identified as a feasible technology
for the low organic/high metals ratio in the SPT wastes.
(Treatability testing will be performed to ensure that
this method will effectively treat SPT wastes). The
sandy-silty soil composition at SPT is also amenable to
fixation.
Several nonthermal treatment process for removing soil
contaminants at SPT were examined, including physical,
chemical, and biological. Of the physical methods, (fix-
ation and soil washing), soil washing was found not to
be effective for removing the relatively low arsenic and
chromium concentrations in the waste, and is not an
effective remedy for organic wastes. For chemical methods,
nucleophilic substitution, or KPEG, only applies to the
organics and has not been demonstrated effective in removing
the dioxin/furan concentrations to the 1 ppb level.
-------
-39-
Biological treatment processes, both on-site and in-situ.-
were examined for soil treatment. Biological treatment
applies only to the organic contaminants in the waste, and
does not treat the metals. However, laboratory tests did
not show reduction of dioxins to the 1 ppb level and no
large scale pilot studies have been conducted on use of
biodegradation for dioxin wastes.
For groundwater treatment, the metals-precipitation
chromium removal technology selected for groundwater
cleanup is a conventional and effective method commonly
used in industrial processes. The other groundwater
treatment method evaluated in detail was ion exchange.
However, ion exchange processes would not be effective
in treating site groundwater due to the potential for
clogging of the resins. Clogging occurs as the trivalent
chromium in the water will readily precipitate out of
solution as chromium hydroxide. In addition, large
quantities of brine are generated, increasing costs over
conventional treatment without greater protection.
Therefore, in comparison to other possible technologies,
soil fixation with a RCRA Cap and conventional groundwater
treatment have been determined to be the most appropriate
technologies for the SPT site.
For groundwater, the remedy selected is considered the
maximum extent to which a permanent solution and treatment
can be practicably utilized. For soil, full permanence
cannot be assured due to limited experience with the
fixation technology. Therefore, long-term monitoring is
required. In terms of treatment, the contaminants are
rendered immobile by application of the fixative agent.
However, this form of treatment does not reduce contaminant
volume or significantly reduce toxicity.
A fully permanent treatment solution for the combination
of wastes present in the SPT soil was not determined to
be feasible at this time. Therefore, the selected remedy
represents the maximum extent to which permanent solutions
and treatment can be practicably utilized.
-------
-------
2
-------
-------
SFUNO RECORDS CTR
1047-00465
ATTACHMENT 2
SELMA PRESSURE TREATING COMPANY SUPERFUND SITE
Final
EXPLANATION OF SIGNIFICANT DIFFERENCES
From the 1988 Record of Decision
I. Introduction
On September 24, 1988, the United States Environmental
Protection Agency (EPA) signed a Record of Decision (ROD) for the
final remedial actions at the Selma Pressure Treating Company
Superfund site, located in Selma, California. The EPA is the lead
agency for the investigation and clean up of the site; the primary
state agency is the California Environmental Protection Agency,
Department of Toxic Substances Control.
Since 1988, the EPA has been conducting treatability studies,
collecting additional field data, and preparing design plans and
specifications for construction of the remedy. In the course of
conducting these additional studies and preparing detailed designs,
the EPA in consultation with other regulatory agencies has modified
certain aspects of the remedial actions and clean up levels. The
purpose of this document is to explain the significant differences
that have come about since the ROD was written in 1988. These
differences, though significant, are not a fundamental alteration
of the remedy described in the ROD.
Under Section 117 of the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980, as amended (CERCLA), 42
U.S.C. §9617, and pursuant to 40 C.F.R. Section 300.435(c)(2)(i)
(55 Fed.Reg. 8666, 8852 (March 8, 1990)), EPA is required to
publish an Explanation of Significant Differences (ESD) whenever a
significant (but not fundamental) change is made to a final
remedial action plan as described in a ROD.
This document provides a brief background of the Selma site,
a summary of the remedy selected in the ROD, a description of the
changes to the ROD that. EPA is now making (including how the
changes affect the remedy originally selected by the EPA in the
1988 ROD), and an explanation of why the EPA is making these
changes to the ROD.
The EPA is issuing this ESD to clarify certain aspects of the
clean up standards for the site, to explain changes in certain
remedial action details described in the ROD, and to document
compliance with Land Disposal Restrictions under the Resource
Conservation and Recovery Act through a Treatability Variance.
-------
This BSD:
(A) changes the term "clean up goal" to "clean up standard"
wherever it is used in the ROD;
(B) revises the clean up standard for arsenic in surface
soils from 50 mg/kg to 25 mg/kg, a more stringent standard;
(C) sets a clean up standard for pentachlorophenpl in ground
water at 1 ppb to comply with a new, more stringent drinking water
Maximum Contaminant Level (MCL) and sets a clean up standard for
pentachlorophenol in soil at 17 ppm;
(D) identifies additional areas of soil contamination that
require excavation and treatment, and revises the total volume and
on site disposal location;
(E) modifies the implementation of the ground water extrac-
tion and reinjection system to reflect a more phased, .observational
approach for the siting and design of the wells, with an initial
phase consisting of 4 extraction and 6 reinjection wells; and
(F) documents compliance with RCRA Land Disposal Restrictions
through a Treatability Variance for the contaminated soil.
As required by 40 C.F.R. Section 300.825(a)(2), the BSD will
become part of the Administrative Record file for the Selma site.
This file is available for public review during normal business
hours in the EPA Region 9 Super fund Record Center, 75 Hawthorne
Street, San Francisco, California, 94105.
Remedy
Site History
The Selma site is located in Fresno County, California, about
15 miles south of Fresno and adjacent to the southern city limits
of Selma. The site comprises approximately 18 acres, including a
4 acre wood treatment facility and 14 acres of adjacent vineyards
that were used for site drainage. Zoned for heavy industrial use,
the site is located in a transition zone between agricultural,
residential, and industrial areas. There are 12 residences and
businesses within 1/4 mile of the site.
The company that originally operated at the site, Selma
Pressure Treating Company, ceased operation and filed for
bankruptcy in 1981. There is another wood treating company, Selma
Treating Company, currently leasing the land and operating on the
site.
The wood preserving process originally employed at the site
involved dipping wood into a mixture of pentachlorophenol and oil,
and then drying the wood in open racks to let the excess liquid
drip off. A new facility was constructed in 1965, and the company
converted to a pressure treating process which consisted of
conditioning the wood and impregnating it with chemical
-------
preservatives. Known chemical preservatives used at the site
include Fluor-chromium-arsenate-phenol, chromated copper arsenate,
pentachlorophenol, copper-8-guinolinolate, LST concentrate, and
Woodtox 140 RTU.
Prior to 1982, discharge practices included: (1) runoff into
drainage and percolation ditches, (2) drainage into dry wells, (3)
spillage onto open ground, (4) placement into an unlined pond and
a sludge pit, and (5) discharges to the adjacent vineyards.
Contamination Problems
Efforts by regulatory agencies to get the company to comply
with clean up orders were unsuccessful and the company went
bankrupt in 1981. EPA placed the site on the National Priorities
List of hazardous waste sites in 1983.
A Remedial Investigation/Feasibility Study was conducted by
the EPA to characterize the areas of contamination and develop
clean up alternatives for the site. The investigations revealed
several areas of soil contamination and a plume of contaminated
ground water eminating from the site. Elevated levels of the heavy
metals arsenic, chromium and copper were found in both surface and
subsurface soils. Soil analyses also showed elevated levels of the
organic compounds pentachlorophenol (PCP) and dioxin/furan. While
there were several contaminants at elevated levels in the soil,
chromium was the only contaminant found to be significantly
elevated in the ground water.
Additional soil and groundwater studies were conducted after
the ROD was signed to provide more detailed characterization for
the design of the remedial actions. The supplemental investigation
of the soils provided a more accurate delineation of the areas of
contamination and identified additional areas needing remediation.
The supplemental ground water investigations provided a more
accurate picture of the extent of contamination and the pumping
characteristics of the aquifer, and revealed that the ground water
table had dropped to below the elevations where the highest levels
of chromium had been found during the original investigation.
Sampling and analysis of the ground water utilizing more sensitive
protocols also revealed that PCP may be present in levels exceeding
a new, more stringent drinking water MCL of l ppb, promulgated
after the ROD was prepared (the previously proposed MCL for PCP had
been 37 ppb).
Remedy Selected in the 1988 ROD
The remedy selected in the original Record of Decision is
composed of two components, one for contaminated soils and one for
contaminated ground water. The soil remediation component consists
of excavating the contaminated soil, treating it on site with a
fixative agent, and then backfilling and compacting the fixed
-------
material on site, fixed areas of soil were then to-be covered with
a RCRA cap. For remediation of the contaminated ground water, the
ROD calls for extraction and treatment of it in an on site facility
utilizing a conventional precipitation, coagulation, and floc-
culation process, with either reinjection or off site disposal of
the treated effluent, and disposal of sludge at an approved off
site landfill. Institutional controls were also required to
prevent future activities or developments on the site that could
impact the integrity and maintenance of capped materials or create
opportunities for increased exposures such as those that would
occur in a residential area.
The ROD defined clean up goals for the soil and ground water
components in terms of organic and heavy metal contaminants that,
according to the risk assessment, would act as indicator
contaminants and drive the clean up. For soils the two driving
organic and heavy metal contaminants were found to be dioxin/furan,
with a clean up goal of 1 ppb by TCDD equivalents, and arsenic with
a clean up goal of 50 ppm. For ground water the ROD set a single
clean up goal of 50 ppb for total chromium, which was the MCL at
the time.
Criteria were also established for treatment of the excavated
soil prior to redisposal. Treated soil was required to meet RCRA
requirements. The maximum concentration of arsenic and chromium in
treated soil, using EP toxicity testing, was 5 mg/1 under 40 C.F.R.
Part 261.24, and 37 ppm for PCP using a total waste analysis under
40 C.F.R. Part 268.
III. Description of the significant Differences and the Basis for
ThoseDifferences
This ESD clarifies and modifies several portions of EPA's 1988
ROD for the Selma site. To the extent that this ESD differs from
the ROD, the ESD supersedes the ROD.
The fundamental nature of the remedial actions for the Selma
site have not changed; contaminated soils are still to be
excavated, treated with a fixative agent, disposed of on site, and
capped in accordance with RCRA standards. Ground water is still to
be extracted, treated using conventional precipitation to remove
chromium contamination, and reinjected into the aquifer.
Certain aspects of the remedy have been modified as a result
of 1) additional data gathered subsequent to the ROD; 2) changes in
Federal and State promulgated standards for contaminants found at
the site; 3) reconsideration during the design phase of certain
aspects of technical and material handling; and 4) clarification of
the applicability of RCRA Land Disposal Restrictions for soil and
debris. The significant changes from the ROD, and the rationale
for those changes, are as follows.
-------
A. Clean up Standards
This ESD uses the term "clean up standard" rather than "clean
up goal". This ESD changes the term "clean up goal" to "clean up
standard" wherever it occurs in the 1988 ROD.
B. Clean up standard for Arsenic in Surface Soils
The clean up standard for arsenic in surface soils identified
in the ROD, 50 ppm, was selected to be protective of all direct
contact exposure scenarios except on site residential development.
The ROD further required implementation of institutional controls
to prevent future on site residential development.
Upon subsequent consultation with the California Environmental
Protection Agency and review of other RODs from throughout the U.S.
that have subsequently set arsenic clean up standards for direct
contact exposure scenarios/ EPA has determined that a lower clean
up standard for arsenic is appropriate, and would not rely on
institutional controls to assure adequate health protection.
Therefore, a new clean up standard of 25 ppm has been established
for arsenic in surface soils at the Selma site. All surface soils
(down to a depth of five feet) containing arsenic in excess of 25
ppm shall be excavated, treated, and disposed of beneath a RCRA
cap.
c. Clean up Standard for Pentachlorophenol in Ground Water
The 1988 ROD did not identify a specific clean up standard for
PCP in ground water, since it had not been detected in ground water
at levels any where near the MCL proposed at the time the ROD was
signed, 200 ppb. Subsequent revisions to the drinking water HCLs
have resulted in the PCP level being lowered to l ppb. PCP has
been detected in ground water on or near the site in levels
elevated above 1 ppb. Therefore, this ESD establishes a clean up
standard of i ppb for PCP in ground water at the Selma site, and
requires that the treated effluent from the ground water treatment
plant meet the same standard before it is reinjected or otherwise
discharged.
The new, stricter MCL for PCP came about due to new evidence
on the potential carcinogenicity of the compound. Based on this
information, EPA and California DTSC re-evaluated the need for a
soil clean up standard for PCP; based on our risk analyses, a new
soil clean up standard of 17 ppm has been selected to assure that
direct human exposures to soil at the site do not exceed the
acceptable risk range prescribed iri the NCP, and to assure that
residual levels remaining at the site do not have the potential to
cause ground water contamination.
It should be noted that the federal MCL for chromium was
changed in July 1992, from 50 ppb to 100 ppb. Since the California
-------
State MCL has not been relaxed, we have retained the sane clean up
standard for chromium in ground water that was selected in the ROD,
50 ppb. Should the State MCL be revised to match the federal MCL,
the clean up standard for chromium in ground water at the Selma
site will also be adjusted to 100 ppb.
O. Additional Areas of Soil Contamination to be Excavated
The 1988 ROD identified four areas where contaminated soil
exceeded clean up standards and required clean up. At the time of
the ROD, the total volume of soils requiring remediation was
estimated at 16,100 cubic yards, and the treated soils were to be
backfilled into the areas from which they were excavated.
Subsequent soil investigations provided more precise volume
estimates and identified additional areas where contaminated soil
exceeds clean up standards and requires excavation and treatment.
The revised list of areas requiring excavation are identified in
Table A. The new estimate for the total volume of contaminated
soil to be excavated is now 11,500 cy. Also, rather than returning
treated soils to the areas where they were excavated, all treated
soils will now be consolidated into a single unit on the site,
under a single RCRA cap.
E. Changes in the Design of the Ground Water Extraction,
Treatment, and Disposal System
The ROD described the ground water remediation both in concept
(i.e. extraction of ground water exceeding MCLs, treatment, and
disposal either by reinjection or off site discharge), and in
detail (construction of 25 extraction wells, 50 feet deep, pumped
at a cumulative total of 1,040 gallons per minute). Although the
concept remains the same (with the addition of the 1 ppb clean up
standard for PCP identified in paragraph C above), the design of
the extraction and treatment system has been modified. Rather than
installing 25 wells, the ground water extraction system will be
developed in phases, with the first phase consisting of 4 wells,
screened at a depth of 70 feet. The treatment plant will be
constructed to an effective design capacity of 250 gpm, and will be
expandable. Treated effluent will be discharged back into the
aquifer through 8 injection wells. Based on information gathered
from the operation of this initial phase of ground water
extraction, treatment, and reinjection, additional wells will be
installed and/or additional treatment plant capacity will be
constructed, as appropriate.
F. Documentation of Compliance with Land Disposal
Restrictions through a Treatability Variance for
Contaminated Soil
As described in the original Record of Decision, RCRA Land
Disposal Restrictions (40 C.F.R. Part 268) are applicable to the
-------
TABLE A
CONTAMINATED
SOILS EXCAVATION***
Area
A
B
C
D
E
T'
G
E
TOTAL
Location
West half of South Percolation
East half .of South Percolation
Unlined Waste Disposal Pond
West half of North Percolation
Ditch
East half of North Percolation
Ditch
Wood Treatment Area
Cal Trans Ditch
Southeast Disposal Area HI
H2
H3
Length
(feet)
335 ft
135 ft
122 ft
235 ft
185 ft
N/A
141 ft
N/A
N/A
N/A
Width
(feet)
14 ft
14 ft
70 ft
14 ft
14 ft
"M25 ft)!
14 ft
"r(25 ft)'
"r.(2S ft)'
"j:(25 ft)'
Depth
(feet)
10 ft
10 ft
*10 ft
25 ft
10 ft
5 ft
1 ft
5 ft
5 ft
10 ft
Soils Volume
(cubic yards)
1740 cy
700 cy
3160 cy
3050 cy
960 cy
360 cy
75 cy
1455 cy
I
f***ll,500 cy
**
»**
Average Depth
Circular Surface Area
Does not include "Possible Contaminated Soils", which, as shown in the Plans,
must also be excavated.
-------
remedial actions for contaminated soil at the Selma.site. However,
the ROD did not appropriately identify the means by which the
remedial actions will comply with the LDRs. The ROD inaccurately
stated that the contaminated soil is considered to be a K001 listed
waste under 40 C.F.R. Part 261.32. K001 is a class of listed
wastes under RCRA consisting of sludges and tank bottoms from
treatment processes for wood preservative wastes. The soil at the
Selma site became contaminated from dripping, spillage, and the
direct discharge of spent wood treating solutions onto the
property. The levels of contamination exceed the threshold for
RCRA characteristic wastes. Therefore, the Selma soil is a
characteristic, rather than a listed RCRA waste.
Because the contaminated soil at the Selma site is a
characteristic RCRA waste, treatment must comply with Land Disposal
Restrictions. Often, Superfund wastes differ significantly from
the waste used to set the LDR treatment standard (LDR treatment
standards are generally based on treating less complex matrices of
industrial process wastes, rather than contaminated soil and
debris). Since treatment standards have not yet been promulgated
for soil and debris, there is a presumption that Superfund response
actions involving the placement of soil and debris will utilize a
Treatability Variance to comply with the LDRs.
The selected remedy for contaminated soils at the Selma site
will comply with the LDRs through a Treatability Variance under 40
C.F.R. Part 268.44. This Variance will result in the use of a
fixation/solidification technology to attain the Agency's interim
treatment level range for the contaminated soil at the site. The
treatment level range established through a Treatability Variance
for each constituent as determined by the indicated analyses are:
Pentachlorophenol 90 - 99% reduction (TWA)
Chromium 95 - 99.9% reduction (TCLP)
Arsenic 90 - 99.9% reduction (TCLP)
Based on treatability studies conducted on the contaminated
soil from the Selma site, it is anticipated that full scale
operation of the selected technology will comply with these
standards.
IV. support Agency comments
The California Environmental Protection Agency, Department of
Toxic Substances Control was provided an opportunity to comment on
this draft ESD before it was sent out for public review. Based on
comments received from DTSC, EPA added language in .the ESD
pertaining to the soil clean up standard of 17 ppm for
pentachlorophenol.
-------
V. Affirmation of the statutory Determinations .
Considering the new information that has been developed and
the changes that have been made to the selected remedy, the EPA
believes that the remedy remains protective of human health and the
environment, complies with federal and state requirements that were
identified in the ROD and in this ESD as applicable or relevant and
appropriate to this remedial action at the time this ESD was
signed, and is cost-effective. In addition, the revised remedy
utilizes permanent solutions and alternative treatment technologies
to the maximum extent practicable for this site.
VI. Public Participation
A public notice fact sheet describing this Explanation of
Significant Differences was distributed to people on EPA's mailing
list of interested community members for the Selma site in May
1992. A public notice was also placed in the Fresno Bee newspaper
on May 8, 1992. The fact sheet summarized the changes proposed in
the draft ESD, identified the repository in Selma where the entire
text of the draft ESD could be reviewed, and provided a period for
public comments from May 8 to June 8, 1992. (A public comment
period was included for this ESD because EPA invoked a RCRA
treatability variance.) EPA received no public comments on the
draft ESD. Therefore, the changes identified in this ESD are
identical to the changes identified in the version made available
to the public in May 1992.
r^-^**-
John C. Wise Date
Deputy Regional Administrator
-------
-------
034 00282
ATTACHMENT 3
TECHNICAL MEMORANDUM ON THE RESULTS
OF
REMEDIAL DESIGN PERCOLATION TESTS
AT THE
SELMA PRESSURE TREATING SUPERFUND SITE
PREPARED FOR
U. S. ENVIRONMENTAL PROTECTION AGENCY
75 HAWTHORNE STREET
SAN FRANCISCO, CA 94105
BY
BECHTEL NATIONAL, INC.
50 BEALE STREET
SAN FRANCISCO, CA 94119
-------
-------
TABLE OF CONTENTS
1.0 SCOPE OF WORK PERFORMED
1.1 Subcontractor Responsibility
1.2 Borehole Permeability Tests
1.3 Monitoring Wells
1.4 Percolation Pit Construction and Testing
2.0 SUMMARY OF TEST RESULTS
2.1 Borehole Permeability Test Results
2.2 Percolation Test Pit Results
2.3 Recommendations for Recharge Pond
FIGURES
Figures
1 Site Plan: Location of Percolation Test Pit
2 Percolation Test Pit As-Built
ATTACHMENTS
Attachments
1 Results of Geologic Logging, Well Installation and Permeability Testing
2 Percolation Pond Infiltration Test Data
3 Recharge Test Infiltration Rate and Treatment Plant Pond Size
Selma\Submittal No. 8 j 9/16/96
-------
-------
1.0 SCOPE OF WORK PERFORMED
Bechtel prepared, issued, and negotiated an invitation for bid for subcontract services at
the Selma Pressure Treating site to provide all necessary labor, tools, supplies,
equipment, personnel, transportation, supervision, suppliers, and materials to: drill test
boreholes; perform borehole permeability tests; construct monitoring wells; construct,
test, and backfill a percolation test pit; and construct, perform infiltration test on, and
abandon (if required) stone columns, if necessary. Based on results of the initial
borehole permeability tests, construction of stone columns (Option 2) was not required
and construction of a percolation test pit (Option 1) was conducted.
By investigating local suppliers and conditions, Bechtel arranged the required water
supply for the percolation test under an agreement with the California Water Services
Company and the Upright Platform Company, adjacent to the Selma site, to supply a
metered-hydrant water supply at commercial rates. Bechtel provided expert oversight
and procured subcontracted plumbing services for meter hookup, piping, and valves
required to deliver a constant, reliable water supply.
The work was performed in the following sequence, under Bechtel supervision, by the
subcontractor:
Drilled boreholes and performed permeability tests;
Constructed monitoring wells;
Constructed .a percolation test pit;
Performed percolation testing;
Backfilled pit; and
Breakdown of equipment, cleaned and restored work site.
1.1 Subcontractor Responsibility
BSK & Associates, Inc., performed all field work at the Selma site and constructed a
temporary working pad adjacent to the test pit location, surrounded by a gated,
lockable 6-foot chain link fence to prevent entry by unauthorized persons or animals.
The working pad included a decontamination area divided into an exclusion zone,
contamination reduction zone and support zone. Responsibilities of the subcontractor
during the execution of the test period were the following:
Obtain any necessary permits for performing the work;
Check drilling and excavation locations for underground utility interference,
per the Existing Site Utilities Plan provided;
Locate and survey boreholes and the boundaries, top, and bottom of the test
pit;
Deliver to the site required construction equipment, materials, tools and
supplies, supervision and labor to:
-------
Drill and sample two test boreholes,
Perform borehole permeability tests,
Install monitoring wells in the two boreholes,
Construct a percolation test pit,
Perform percolation testing,
Backfill percolation test pit, and
Breakdown and remove equipment and supplies from site; and
Clean and restore work areas.
All drill cuttings were stockpiled on plastic sheeting in an area adjacent to the test pit.
Pit excavation materials were used to construct the berm around the test pit. The drill
cuttings and excavated soil were backfilled into the test pit at the end of the testing
period. Dust control was provided during drilling and excavation activities by use of
water spraying to minimize visible air emissions. After completion of testing, fencing
was removed and work areas were cleaned and restored to as near their original
condition as feasible. Locks were provided for the two monitoring wells to allow their
future use in monitoring recharge pond performance.
1.2 Borehole Permeability Tests
Two boreholes were drilled adjacent to the location of the outer boundary of the test
pit to: facilitate the performance of permeability tests at 5 and 10 feet below ground
surface (bgs); and facilitate the installation of two monitoring wells. The two test
boreholes were drilled with nominal six-inch diameter hollow stem auger to depths of
18 and 55 feet bgs. Eight subsurface soil samples were collected from the boreholes
using a Standard Penetration Test sampler, in accordance with ASTM D1586-84.
Permeability tests were conducted at depths of 5 and 10 feet bgs in each borehole. The
tests were performed by measuring the rate of water needed to maintain a constant
head inside the hollow stem augers. Coarse sand was utilized in the bottom of the hole
to reduce caving. The borehole permeability tests were conducted for periods of 23 to
60 minutes, until a steady-state flow rate was approximately achieved.
1.3 Monitoring Wells
Subsequent to the drilling and testing of the boreholes described above, two
monitoring wells were completed in each of the two tested boreholes. Work
associated with these wells was performed in accordance with Technical Specification
TS-034-003. The monitoring wells were installed within the vadose and saturated
zones to bottom depths of 18 and 55 feet bgs, respectively. Wells were completed
inside 6-inch hollow stem augers and constructed with two-inch diameter, Schedule-
40, polyvinylchloride (PVC) casing. The bottom 10 feet of the wells were transversely
slotted with 0.01-inch width slots and terminated with a threaded cap. The top of the
PVC casing was extended approximately three feet above ground.
-------
The annulus was filled with approximately 12.5 feet of filter pack, consisting of
Monterey #3 silica sand, from the bottom of the well to approximately two feet above
the well screen. Prior to the addition of a bentonite seal, the well was surged to settle
the surrounding sand filter pack. A 2.5-foot plug of hydrated bentonite pellets was
placed on top of the filter pack, prior to the grout seal. The remaining annulus was
filled to ground surface with a neat cement. Protective surface casing of steel was
installed to a depth of three feet and threaded with a locking cap.
1.4 Percolation Pit Construction and Testing
A test basin was constructed with bottom dimensions of 25- by 25-foot square,
surrounded by slopes cut to a 2.5 horizontal to 1 vertical grade. The bottom depth was
5 feet bgs, as directed by Bechtel. A 2- to 3-foot high protective benn was constructed
around the test pit with the excavated soil. Compaction of the test pit bottom was
minimized during excavation. Compaction of the slopes was performed as deemed
necessary to prevent slumping. The test pit location and as-built drawings are shown
in Figures 1 and 2, respectively. A drop basin was constructed at the water inlet to
minimize erosion during pond filling and testing. A staff gauge was installed in the
basin near the edge for measurement of water depth. In addition, an evaporation pan,
rain gage, and thermometer, were also provided for the duration of the testing.
The percolation pit test consisted of the following work:
Filled the test basin to approximately 2.75 feet height of water, and
monitored and controlled the flow of water into the test pit continuously for
48 hours; and
Subsequently performed periodic work, initially on a daily basis:
Measured water level in test pit at the staff gauge,
Measured water temperature in test pit,
Adjusted the inflow of water to maintain a relatively constant water
depth of 2.5 to 3 feet,
Measured evaporation rate and refill evaporation pan,
Measured rain gauge, if any precipitation occurred, and
Measured water levels, if any, in the two test monitoring wells.
2.0 SUMMARY OF TEST RESULTS
Geologic logging of the boreholes, borehole permeability testing, and well installation
are described in Attachment 1. The percolation test data recorded by the subcontractor
are provided in Attachment 2. The calculation of the recharge rate and estimate of
pond size required for the treatment plant are provided in Attachment 3. The
-------
.net, mtt.
-------
Calculation Sheet
Originator
Project -5g/*d.
Subject &
Date
TsrA-h*a Job No
Bochtel
Calc. No..
Checked.
Rev. No.
Date
fZ^_2
2
3
4
5
6
7
8
9
10
11
12
13
15
16
17
18
19
20
21.
22
23
24
25
X
27
28'
29
30
32
33
34
35
36
is.
A
A
Tee. ef
Toe c~f
,*,«,'-tvf,'«a «*<£// (ssf ty}
I * */
-------
following sections briefly summarize the results of the borehole permeability and
percolation pit testing.
2.1 Borehole Permeability Test Results
The borehole permeability test results indicated that the soils in the shallow vadose
zone, at 5 feet and 10 feet below ground surface, would be suitable for the percolation
pit test (Option 1). The vertical hydraulic conductivity was estimated to be
approximately 2 feet per day, based on the average of four tests. An area of
approximately 170 feet by 170 feet was estimated to be required for recharge of the
treatment plant design capacity of 300 gallons per minute, assuming a recharge rate
approximately equal to the estimated vertical hydraulic conductivity. Sufficient area
of unused land remains at the Selma site to accommodate much more than this
preliminary pond size.
2.2 Percolation Test Pit Results
Subsequent to pond filling, the test period duration was approximately 45 days (12:11
on July 9 through 13:32 on August 23, 1996). Based on hydrant meter readings, the
total water volume placed in the pond was 391,000 gallons, with an average flow rate
of 6.02 gallons per minute. The total pan evaporation measured during the test was
20.9 inches. The measured pan evaporation, assuming a pan coefficient of 0.7,
represents an evaporation rate of 0.03 feet per day. The net infiltration rate, with
negligible adjustment for evaporation, was estimated to be 1.1 feet per day, assuming
an effective infiltration area of 32 feet by 32 feet for the percolation test.
Significant decreases in the flow rate or infiltration rate during the test did not occur,
and in fact, the final rate was slightly higher than during the initial portion of the test.
A relatively steady rate of increase in the water table level was indicated to begin
about 4 days after starting the test, but the change (about 1 ft in 45 days) may reflect
slight seasonal variation in the local water table in combination with slight water table
mounding. The shallow monitoring well (screened 8 to 18 ft bgs) remained dry
throughout the test, suggesting absence of perched water mounding.
2.3 Recommendations for Recharge Pond
By direct extrapolation of the percolation pit test results, the required pond bottom area
for the treatment plant discharge of 300 gallons per minute is 228 feet by 228 feet.
However, pond bottom dimensions of 200 feet by 260 feet are recommended for the
recharge pond, to more conveniently fit within the unused land at the Selma site. A
duplicate or standby pond is recommended to allow continuous operation of the
treatment plant when maintenance activities are required in the recharge pond.
The infiltration capacity of the constructed ponds must be verified during startup.
Activities during pond construction, such as unintended excessive reworking and
-------
compaction of the pond bottom during excavation, could result in infiltration rates
different than those estimated from the recharge test. Such activities which would tend
to reduce the infiltration rate are to be avoided.
-------
-------
ATTACHMENT 1
RESULTS OF GEOLOGIC LOGGING, WELL INSTALLATION, AND
BOREHOLE PERMEABILITY TESTING
-------
-------
C3-1 OC266
Bechtel National, Inc.
50 Beale Street (94105)
P.O. Box 193965 (94t19)
San Francisco, CA
ARCSWEST - Selma Pressure Treating Site
To:
Company:
From:
Phone:
Location:
M. Sholley and W. Sweet-Dodge
Bechtel National
M. Janowiak
8-8224
San Francisco, CA
Date: July 1
cc: Prem
M. L
, 1996
Attanayake
Introduction
The Selma Pressure Treating Superfund Site is located in Selma, California. The site
was placed in the Superfund program because of groundwater and soil contamination.
There is a groundwater pump-and-treat system proposed to control migration of a
chromium plume. The system will pump up to a maximum of 250 gallons per minute.
Treated groundwater will be recharged to the aquifer in an on-site recharge system.
On June 27,1996, BSK Engineers drilled and logged two boreholes and conducted
borehole permeability tests (Figure 1). Monitor wells were installed in the boreholes.
The borings were drilled near the area where a recharge pilot test will be conducted.
The purpose of these borings was to test the permeability of the shallow soils and to
install monitor wells for the recharge pilot test.
Permeability test results were used to decide if recharge is best attained by recharge
basins'or by stone columns. Initial results indicate that the vertical hydraulic
conductivity in the shallow vadose zone is approximately 2.0 ft/day (average of four
tests, Kh/Kv = 10 from Table 1).
Methods, Results, and Discussion
The following presents the field methods and results of the geologic logging, well
installation, and permeability testing.
Geologic Logging
Split-spoon sampling was conducted from 3.5 feet bgs to 45 feet bgs in boring #1. The
upper 8 feet of soil was a damp silty sand to sandy silt. These soils were not cohesive.
At 8.5 feet bgs, there was a distinct contact where the deeper material was a fine sand.
Only a trace of silt was present. The fine sand extended to a depth of approximately 18
feet bgs. From 18 to 25 feet bgs, the lithology was a silty sand to sandy silt From 25
feet to approximately 40 feet bgs, a fine sand was encountered. At approximately 40
-------
feet, there was a caliche or weakly-cemented silty sand. At this depth there was a color
change from olive brown to a reddish brown. Groundwater was encountered at 49 feet
bgs.
At site #2, the lithology was similar to site #1. There were very thin coarse sand beds (2
to 3 inches) encountered in this zone in the 17 to 18 feet bgs interval. This indicates that
the silt encountered from 18 to 25 feet bgs at site #1 may not be vertically continuous.
Well Installation
A monitor well was installed in Test #1 with the screened interval extending from 54.5
feet to 44.5 feet bgs in this borehole. In Test #2, the monitor well screened interval
extended from 17.5 to 7.5 feet bgs.
The wells were constructed with 2-inch diameter, schedule 40 PVC, 0.010-inch machine
slot screen and blank casing to the surface. Monterey #3 sand was used for the filter
pack, which extended 2 feet above the top of the screen. Bentonite chips were placed on
top of the filter pack and hydrated. Neat cement grout was placed over the bentonite
plug to ground surface and the wells were completed with a 6-inch diameter surface
casing.
Test #1 was installed as a water table well to monitor mounding associated with
recharge water from the pilot test. Test #2 was installed at the top of the silt unit
encountered at a depth of 18 feet to monitor potential perching on that unit as the
recharge test progresses.
Permeability Testing
Permeability testing was done as follows:
1. a soil sample was collected from 3.5 to 5.0 feet bgs,
2. the borehole was reamed to 5.0 feet,
3. augers were lifted one foot,
4. sand was placed into the hole to a point several inches into the auger stem,
5. a water-level sounder was placed at a preset depth 10 inches above the sand,
6. the hole was filled with water up to the depth monitored by the sounder using one-
liter containers,
7. elapsed time was measured and recorded as time since first water was placed in the
borehole,
8. one liter of water was added when the sounder indicated water levels dropped to
just below the sounder level,
9. when water take had stablized (usually after about 10 minutes), the test was
continued to measure the average rate of take in the borehole.
By adding water in one-liter increments the head was maintained at a +/- 2.5 inch
interval about the sounder level.
-------
The first test at site #1 was conducted with a much higher head (several feet) rather than
10 inches.
Table 1 is summary of test parameters and the resulting vertical hydraulic
conductivities calculated for each of the four tests. The vertical hydraulic conductivities
ranged from 0.35 ft/day to 3.01 ft/day. The shallow lithologies had lower Kv
compared to the deeper lithologies, but only marginally at site #2.
Summary
The vertical hydraulic conductivities, as measured at the two boreholes, are high
enough that a recharge pond should be tested instead of a stone column. There appears
to be sufficient area at the Selma Pressure Treating site to accommodate ponds of the
dimensions needed for recharge of 250 gpm (Table 2). This will be further tested during
the pilot study. Monitor wells installed in the test basin area can be used to evaluate
perching of the recharge water and mounding effects on the water table.
References
(see tables 1 and 2)
Attachments
1. Geologic logs (final logs due from BSK)
2. Well construction diagrams
3. Permeability Test Data
-------
Table 1
Selma Near-Surface Infiltration Tests
Test
location
,
i
2
2
Test
depth
(inches)
60
120
60
120
Material tested
Silly Sand
(20 to 40% sill)
Fine Sand with Silt
(< 10% silt)
Silly Sand
(20 to 40% sill)
Fine Sand with Sill
«10% silt)
Hole
diameter
jnches)
6
6
6
6
Effective
area of
lest hole
(ft2>
0.20
0.20
0.20
0.20
Approximate
head
(inches)
30
10
10
10
Test
duration
(mm)
60
30
30
23
Water
volume
added
(mL)
43000
21000
23000
22000
Time
required
10
infiltrate
(min)
55
19.25
29
23.3
Flow
rale
(L/hr)
46.91
65.45
47.6
56.7
Row
rale
(ft'/day)
39.76
55.48
40.3
48.0
Vertical
hydraulic
conductivity,
K,"'
(assume
(ft/day)
2.34
16.32
11.9
14.1
Vertical
hydraulic
conductivity,
(assume
(ft/day)
0.35
3.01
2.19
2.60
Notes
Higher head than other tests
Cleaner sand in sampler shoe, may
be reason for higher K than at ff 1
Notes:
'" Horizontal hydraulic conductivity, K» = Q In I mL/D + ( 1 + (mL/D)! )")/(2itLHt) (Lambe & Whitman, p. 284-285, for open borehole, uniform soil, constant head),
where "transformation ratio", m = ( K|/K,) °5, and D = hole diameter, L = saturated length, H< = constant head, and Q = water flow. Try in = 01, 1, and 10.
\\IHHI IK* XI.1
I'agt 1 oj I
AfO'J 7/2/Vrt 7 29AM
-------
Table 2
Green & Ampt Infiltration Equation
Pond Sizing Estimate
Assume Kt from Lambe & Whitman analysis corresponds to K^..^t:
0.35
3.01
2.19
2.60
-2.0
-2.0
-2.0
-2.0
2
2
2
2
10
10
10
10
Assume Kt from Lambe & Whitman analysis corresponds of v t;
0.49
4.20
3.06
3.63
1.28
11.04
7.96
9.53
0.82
7.02
5.08
6.03
0.66
5.65
4.11
4.88
-2.0
-2.0
-2.0
-2.0
-2.0
-2.0
-2.0
-2.0
-2.0
-2.0
-2.0
-2.0
0.67
0.67
0.67
0.67
0.67
0.67
0.67
0.67
0.67
0.67
0.67
0.67
1
1
1
1
2
2
2
2
3
3
3
3
0.35
3.01
2.19
2.60
0.35
3.01
2.19
2.60
0.35
3.01
2.19
2.60
Notes:
(l) Infiltration rate, v, = K (Hw + Lf - /» ) / Lf (Bouwer. 1978, p. 253).
m Required pond dimension, W = Q / !£
Required
flow.
Q
(gal/min)
250
250
250
250
250
250
250
250
250
250
250
250
250
250
250
250
Required pond
dimension.
W«
(ft)
371
126
148
136
194
66
78
71
243
83
97
89
270
92
108
99
-------
Elapsed
Time
min
1
2
3
5
7
9
13
16
19
23
Elapsed
Time
mm
1
2
4
6
8
10
13
16
19
sec
33
13
20
9
40
56
10
24
41
20
-
sec
55
46
30
13
35
55
30
20
15
1.550
2.217
3.333
5.150
7.667
9.933
13.167
16.400
19.683
23.333
1.917
2.767
4.500
6.217
8.583
10.917
13.500
16.333
19.250
Vol. Added
(liters)
13
1
1
1
1
1
1
1
1
1
._
Vol. Added
(liters)
13
1
1
1
1
1
1
1
1
,
Total Volume
(liters)
13
14
15
16
17
18
19
20
21
22
Total Volume
(liters)
13
14
15
16
17
18
19
20
21
Water
Depth
(ft bgs)
-8.5
-8.5
-8.5
-8.5
-8.5
-8.5
-8.5
-8.5
-8.5
-8.5
Water
Depth
{ft bgs)
-8.5
-8.5
-8.5
-8.5
-8.5
-8.5
-8.5
-8.5
-8.5
Infiltration Rates (Site #2, 10 feet
bgs)
25 -i 1
t A *
B 20 . *
< + * *
fp-v*
i =. 10
5
i 5
0
0.000 5.000 10.000 15.000 20.000 25.
Elapsed Time (mln)
000
Infiltration Rates (Site #1,10 feet
bgs)
^ 25 -i
i20 '«**
$« .«»*
| 10
i s-
0.000 5.000 10.000 15.000 20.
Elapsed Time (mln)
DOO
-------
Elapsed
Time
min
10
17
17
17
26
35
40
45
50
Elapsed
Time
mm
1
2
4
6
8
11
13
16
19
22
25
29
sec
0
15
45
58
50
0
0
0
0
sec
21
25
26
18
43
0
32
30
30
25
50
5
10.000
17.250
17.750
17.967
26.833
35.000
40.000
45.000
50.000
1.350
2.417
4.433
6.300
8.717
11.000
13.533
16.500
19.500
22.417
25.833
29.083
Vol. Added
(liters)
27
2
1
1
4
2
2
2
2
Vol. Added
(liters)
12
1
1
1
1
1
1
1
1
1
1
1
Total Volume
(liters)
27
29
30
31
35
37
39
41
43
Total Volume
(liters)
12
13
14
15
16
17
18
19
20
21
22
23
Water
Depth
(ft bgs)
-1
-1
-1
-1
-1
-1
-1
-1
-1
Water
Depth
(ft bgs)
-3.5
-3.5
-3.5
-3.5
-3.5
-3.5
-3.5
-3.5
-3.5
-3.5
-3.5
-3.5
Infiltration Rates (Site #1 , 5 feet bgs)
§40
j» 30
| 20
3 10
1
0.000 10.000 20.000 30.000 40.000 50.
Elapsed Time (min)
>
uoo
Infiltration Rates (Site #2, 5 feet bgs)
Cumulative VoL (liters)
o 01 o in o N
O.C
XX) 10.000 20.000 30.<
Elapsed Time (min)
-
XX)
-------
GEOLOGIC DRILL LOG
1SI
fo
')».»
3" 5"
/3>o -,
-?
AV. J/j
WATIft
PMCMUHC
i
AM ckA ***«* me*
jflf^ l/ft ^
^
/7
B «««/»<
2-
- s
'' *'> '-* ' -"V -' -^<-
2.5-'
rt,.
r.
7K
. <=« J£.,
-------
?/^ ,55
<7r*vy>(J7
r-:-
-zc
1 I
t
M
-i
M.HJL
NnMXI^
HIXVM
:
- T
901 11IHQ 31901039
-------
GEOLOGIC DRILL LOG
^r
T&k
«« JrrJ |r«T*ia«»Ti
/#
.,,,. ,,_- /_
WATIM
PltCMUItl
'
r
r
f.r
/
-------
MONITORIN6 WELL
JO. NO.
MOW
Wl
COUPLITto
Wl /» i
// fa..*
S-fl ll A f) l_ a <, , 'i^^ , . -J
1
l.J ' ' £
GENE RALIZED GEOLOGIC LOG
If
1 "*
V*
V*
\
j
T
A
i
*
i
t
c
K
*
1
f
4
1
j
i
i
^
J,.-
EUEV
l
4
J '
J
r
ATI ON TOP Of RISER CASINO ___
" ^ GROUND SURFACE
SURFACE CASING
TYPE: .. "f^ f^ { t*j r £ **t-*t-£w»/^ £A^}^-
f
BACKFILL MATERIAL
RISER CASING
DIA: 2 "
J
1
ANNULAR SEAL
0 Iti C 1 *-^ »- 1 »*t
FILTER PACK
TYPE:
L
r
SCREEN:
DIA: 2" TYPE: <>:4.1<> f"J^
OPENINGS" WIDTH: 0.019"
TYPE: A,!,. ,(. .- » .;.*
"TcfT^1 1
DEPTH
s-
^.r
'4ft
^?^
r^
r
__
ELEV.
-------
-------
1
*
" " * ' \
v'
_ f
1'
2
a
a
FIELD PERMEABILITY TEST REPORT BECHTEL INCORPORATED
PROJECT:. 5 £t-Mfr P^wr^Tmed,'-*
LOCATION:. tfL /U A C fir
CLIENT: /rPA
CONTRACTOR:
DRILLER:
&{Y~ INSPECTOR:
INSTALLATION DATE : (, 111 lit' TEST DATE : C 1 * T~ If (,
TJPE INSTAL
IATTOM BOREHOLE
1 _^^* ft 1 ^} 1" ' J
TYPE TEST Cpv^ 7 O~vA r S&A \^il
RELATIVE TO GROUND SURFACE
> Ground Surface
i Ground Surface
STATIC h
NG BOTTOM C
(FEET):
fATFR A)rv£^
E CASING
-XO'' BOTTOM OF TEST- 5". fl '
5-0"
JOB NO. 2o3 ^^ -c>3V
TEST
NO. *^L
BORING NO. 7/-J7-- 1
LOCATION
SHEET / OF
REMARKS ? SKETCH
^4?'
w^ «r-^
PERMEABILITY TEST DATA
TIME
(HOURS-MINS!
&-5~ ^.^
0-2? _,^
? ^;<^
» ^*^ p' *
f '
r*;^
ELAPSED
TIME
(MIN..SCC.)
l^.'OO.'fiO
/^'.p
_2 ^*: 5-^
3O :«?r
J?-? ,TJ
35"; ot3
3$',£~O
unioo
f/r"; *0 /"7
_T<5: «o
rr :o6
MCTER
READINO
(+ 2. li-Kdj
f-( 1 l:lw«.)
f-dfi+lr*.
f-f-t] l;fo,e$\
'
/"fA l,K*i}
/4- 3. )^c^
iT/2 /./^j
r+s, AVv#$)
WATER
QUANTITY
(GALLONS)
^-Sf. J^e^
<2. °l ///twr
3^ :^t
35- ///^
5-9. /;A,tfJ.
19 /iVv^S
^J /;^e >;-^^s
DEPTH TO WATER
FROM TOP OF CASING
(FEET1 - :
- 1..4
--2.3
-2 , C,
-2.3
.
- 3. 2_
-2. i
- 2. ?-
- 2 . O
- a. 2.
- 2* 3
-a. /
^ V
- .2 /
-^.. ^9
''1,1
- 2.. 2-
REMARKS
^/ $, 7 iQ, H
12. 13 '^ /f / £.
lit /A 14
-------
X
\
.i
!
t
1
I
1
1
«
FIELD PERMEABILITY TEST REPORT BECHTEL INCORPORATED
PROJECT:. StsLMA : JOB NO. 2.03 -j. f
LOCATIONr, ' TEST NO. .2-
CLIENT- __pP~K " - '" BORING NO. -TZ Ground Surface
^ Ground Surface
STATIC M
NG BOTTOM C
BOTTOM 0
(FEET):
ATPJI
F CASING?^
F TEST '3,0 '
REMAW
.i^i«
^
3 7 SKETCH
i i
r
\W
3't.
r1
PERMEABILITY TEST DATA
' TIME
(HOURS-WINS!
io-~lo
0. '' »,.-
h '- C" i_ ' -v
. }. C u- . .«-
2.. 3
3-'.'~3~*-<~
'^.L'-'.^.
2 .^ u..--
^ . £) v'-u
V '
ELAPSED
TIME
(MIN.-SEC.)
/: r <
?:i6
t'l $o
i'. 13
? ' ^ e"
IO:'.±0
1 4 \3.(J
11 '-if.
METER
READ IN 0-
** -1 I.-H.
-h I' 1 / l**e
4-1 i,+v*-
4- . /'hrt.
-4 ' l."tfc^
fl Jl-^vr
+/ l.'-n-t
J. 1 /.** fi~
WATER
. QUANTITY
' /? j-4- c-
' Of // ' i- «5
/V .'.'TV-S
/ r /.-^w-j
/ t. ^.A-_
/'7- /,-n-e.
i O i ^
'? A4wej
J?^ llf.tf '
2\ J.+V2.J
DEPTH TO WATER
FROM TOP OF CASINO
(FEET) =>
~~ & O
- i^O
- f. o
' o O
-Y-^
--?. o ' -
-f.o
-r. o
~ ' .
'
REMARKS
-------
FIELD PERMEABILITY TEST REPORT
BORING NO.
.TEST NO..
SHEET
OF
LOCATION.
DRILLING CONTRACTOR.
DRILLING Fimn A A
ftr
.TEST DATE.
.DRILLER _
.SUPERVISOR.
TYPE OF TEST.
TYPE OF CASING
LENGTH OF CASING
TEST SECTION LENGTH
J.D..
I.D..
.SOIL DESCRIPTION.
DEPTH OF TEST (FT.).
r.
ELEVATIONS (FT.AMSL):
SURFACE ELEVATION i
.BOTTOM OF CASING^.
"^ f
TOP OF TEST V 5 RftTTOM OF TEST.
STATIC WATER 1 FVFL "J. 5" 4 c. J
REMARKS /SKETCH
PERMEABILITY TEST DATA
CLOCK TIME
(HOUR&MINS.)
ELAPSED TIME
(MIN.)
METER
READING
WATER
QUANTITY
DEPTH TO
WATER (FEET)
REMARKS
/2
2.0
/ (f
://
-il.
-3.
30
+1
- ?.
j.
-3.
-------
' I
r
-A
5
i i
VA)
^H^S^XJ^- :A
o
P
u
0
O!
\A i
$ fi
\ tA
Jf
i)t
(°
-------
ATTACHMENT 2
PERCOLATION POND INFILTRATION TEST DATA
-------
-------
POND INFILTRATION TEST DATA
SELMA PRESSURE TREATING Page 1 of 5
Date
(1996)
07/09
Time
(hr.)
0605
0705
0810
0902
0955
1104
1211
1310
1408
1505
1602
1659
1808
1900
2003
2100
A Time
(hr.)
1.00
1.08
0.87
0.88
1.15
1.12
0.98
0.97
0.95
0.95
0.95
1.15
0.95
1.05
0.95
Water Level
(in. from hue)
0.0
14.3
21.0
28.0
31.9
33.1
33.0
33.0
33.0
32.9
32.9
32.9
32.8
32.5
32.4
Meter
(ft1)
792580
793345
794000
794580
795240
795875
796048
796082
796117
796150
796184
796217
796278
796303
796339
796370
&VoL
(ft1)
765
655
580
660
635
173
34
35
33
34
33
61
25
36
31
Ave,Flow
(*P»»)
95.4
75.6
83.1
93.5
68.8
19.3
4.3
4.5
4.3
4.5
4.3
6.6
3.3
4.3
4.1
Depth to
Groundwater
(in. from ToC)
TH.1
(South)
45.85
45.86
45.83
45.82
,
45.85
Pan Evaporation
Water HL (in.)
intt.
6.5
end
Water
Temp
CF)
Evap.
(inches)
- /»»_'.'1
BSK
-------
POND INFILTRATION TEST DATA
SELMA PRESSURE TREATING Page 2 of 5
(continued)
Date
(199«)
07/10
Time
0>r.)
21S9
2258
2400
0058
0158
0300
0400
0500
0600
0700
0804
0858
1000
1103
1210
1306
140-1
A Time
(kr.)
0.98
0.98
1.03
0.97
1.00
1.03
0.97
1.00
1.00
1.00
1.07
1.10
1.03
1.05
1.12
0.93
0«J7
Water Level
(In. from bate)
32.5
32.6
32.8
32.8
32.9
33.0
33.0
33.1
33.3
33.3
33.3
33.0
33.0
32.9
32.9
32.9
125
Meter
(ft*)
796418
796466
796521
796571
796623
796678
796731
796786
796841
796870
796892
796912
796935
796959
796985
797008
7')7
-------
POND INFILTRATION TEST DATA
SELMA PRESSURE TREATING Page 3 of 5
(continued)
Date
(1996)
07/10
07/11
Time
(hr.)
1504
1605
1703
1756
1900
2000
2100
2159
2259
2400
0101
0200
0300
0359
0500
0600
1300
A Time
(hr.)
1.00
1.02
0.97
0.88
1.07
1.00
1.00
0.98
1.00
1.03
1.00
0.98
1.00
0.98
1.02
1.00
700
Water Level
(In. from bate)
32.4
32.5
32.5
32.4
32.4
32.4
32.4
32.4
32.3
32.4
32.4
32.4
32.4
32.4
32.4
32.4
325
Meter
(ft1)
797058
797096
797133
797168
797213
797250
797290
797327
797367
797410
797451
797493
797534
797576
797613
797651
797940
AVoL
(If)
27
38
37
35
45
37
40
37
40 ,
43
41
42
41
42
37
38
289
Ave.Flow
(gpm)
3.4
4.6
4.8
4.9
5.2
4.6
5.0
4.7
5.0
5.2
5.1
5.3
5.1
5.3
4.5
4.7
51
Depth to
Groundwater
(In. from ToQ
TH.1
(South)
45.85
45.84
45.%
45.99
45.99
45.99
45.99
45.99
45.99
45.95
Pan Evaporation
Water Ht. (in.)
init.
6.1
5.8
end
6.1
5.8
Water
Temp
CF)
97
74
-
Evap.
(inches)
0.4
0.3
Job 01 -40-022H
-------
POND INFILTRATION TEST DATA
SELMA PRESSURE TREATING Page 4 of 5
(continued)
Date
(1996)
07/11
07/12
07/13
07/14
Time
(hr.)
1410
1500
1600
1700
1800
1900
2000
2100
2202
2305
2359
0830
1100
1430
1432
1630
1436
A Time
(hr.)
2.17
0.83
1.00
1.00
1.00
1.00
1.00
1.00
1.03
0.95
0.98
8.52
1.50
3.50
24.03
1.97
22 10
Water Level
(In. from bate)
32.5
32.5
32.5
32.5
32.3
32.4
328
32.4
32.3
32.4
32.4
32.4
32.4
32.5
33.1
33.1
325
Meter
(If)
797990
798020
798070
798120
798150
798190
798230
798270
798320
798350
798386
798755
798824
799002
800255
800350
801408
AVoL
(ft1)
50
30
50
50
30
40
40
40
50
30
36
369
69
178
1253
95
1058
Ave.Fkm
(SP*»)
2.9
4.5
6.2
6.2
3.7
5.0
5.0
5.0
6.1
3.9
4.6
5.4
5.7
6.3
6.5
6.0
60
Depth to
Groundwater
(in. from ToQ
TH.1
(South)
45.92
45.92
45.92
45.92
45.92
45.92
45.93
45.95
45.98
45.97
45.99
45.99
45.99
45.98
45.89
45.89
4588
Pan Evaporation
Water Ht. (In.)
Intt
5.6
5.4
6.6
5.9
6.2
end
5.6
5.4
5.9
6.2
Water
Temp
fF>
88
77
99
" 98
Evap.
(inches)
0.2
0.2
0.7
0.5
BSK
-------
POND INFILTRATION TEST DATA
SELMA PRESSURE TREATING Page 5 of 5
(continued)
Date
(1996)
07/15
07/16
07/17
07/19
07/22
07/24
07/28
07/31
08/02
08/05
08/08
08/09
08/13
08/18
08/23
Time
(hr.)
1010
1040
1030
0830
1830
1831
0630
1400
1702
1803
1558
1430
1820
(128
1332
A Time
(hr.)
19.57
24.33
24.13
48.13
82.00
48.00
84.00
79.50
51.00
71.00
48.01
22.51
99.83
113.17
122.01
Water Level
(In. from bate)
38.8
35.8
33.8
32.3
30.2
32.5
35.3
39.8
33.5
30.0
30.0
29.0
33.3
35.0
38.3
Meter
(If)
802581
803902
804842
806771
809690
811966
820612
828230
848297
*VoL
(If)
1173
1321
940
1929
2919
2276
8,646
7,618
20.067
Ave. Flow
(ipm)
7.5
6.8
4.9
5.0
4.4
5.9
7.5
4.4
7.5
Depth to
Groundwater
(In. from ToC)
TH.1
(South)
45.86
45.85
45.83
45.80
45.73
4569
45.63
45.55
45.50 .
45.44
45.33
45.20
44.91
44.79
Pan Evaporation
Water Ht (in.)
Init
5.9
5.7
5.6
5.5
4.7
6.1
4.8
5.1
5.5
6.0
5.6
3.4
6.1
5.5
end
6.2
6.1
6.6
6.4
7.0
6.6
6.8
6.6
7.4
7.1
5.6
8.5
7.7
5.5
Water
Temp
CF)
78
78
80
79
92
90
72
86
88
88
87
90
80
82
Evap.
(Inchet)
0.3
0.5
0.5
1.1
1.4
0.9
1.8
1.7
1.1
1.4
1.5
1.8
2.4
2.2
Job oi-io-u::fi
BSK
-------
-------
ATTACHMENT 3
CALCULATION OF RECHARGE TEST INFILTRATION RATE AND
TREATMENT PLANT POND SIZE
-------
-------
CALCULATION COVER SHEET
PROJECT
AKCSWEST - Selma Pressure Treating
JOB NO.
20376434
SUBJECT
Recharge Test Infiltration Kale A Treatment Plant Pond Size
CALCNO.
C-003
SHEET
/
DISCIPLINE
Ceotech. & Environ. Technologies
CALCULATION PRELIMINARY
STATUS | Xj
DESIGNATION
CONFIRMED
. cn
SUPERSEDED
cu
' VOIDED
COMPUTER SCP
PROGRAM/TYPE [T] YES \ | NO
MAINFRAME PC
i i m
PROGRAM NO.
EXCEL
VERSION/RELEASE NO.
5.0
No.
Initial calculation
Ftotson tor Revision
9
Tool Nad
Stab
9
US She*
No.
^7*^ffuOut
&Tr
OMCked
AppraMd
Data
Record of Revisions
-------
-------
SUBJECT
CALCULATION SHEET
Kediargt Tea Infiltration Rate & Treatment Plant Pond Sat
BY Michael Sholley DATE 9/11/96
PROJECT
JOB NUMBER
CALCNO.
SHEET NO.
SHEET REV
AKCSWEST-Selma
20376-034-023
C-O03
2 of 9
0
Table of Contents
1. Purpose ~ 3
2. Methodology 3
3. Results 4
4. Conclusions 4
5. References 5
Table 1 Recharge Test Data and Results
Figure 1 Average Pond Water Depth, Flow Rate, and Infiltration Rate
Figure 2 Depth to Ground-Water Table
-------
-------
0 CALCULATION SHEET
SUBJECT Recharge Tta Infiltration Rale A Treatment Plant Pond Size
BY Michael StoUey DATE 9/11/96
PROJECT
JOB NUMBER
CALCNO.
SHEET NO.
SHEET REV
ARCSWEST-Selma
20376-034-023
C-003
3 of 9
0
1. Purpose
The purpose of this calculation is to determine the infiltration rate during the pond recharge test
conducted July 10 through August 23,1996, at Selma Pressure Treating site, and to estimate the
required pond dimensions for the groundwater treatment system design capacity of 300 gal/min.
This work is conducted as part of Subtask 023, "Percolation Tests", based on the Activity Work
Plan (Bechtel, 1995b). Additional work completed for Subtask 023, installation of test
monitoring wells and borehole permeability tests, are reported in Bechtel memorandum from
Matt Janowiak, dated July 1,1996. The design capacity requirement of 300 gal/min includes a
contingency of 50% above the expected full-scale extraction system rate of 200 gal/min, based on
an expected maximum of ten extraction wells at 20 gal/min per well (Bechtel, 1995a, pg. 6-1).
2. Methodology
Field measurements of cumulative flow at various times were used to determine average flow
rate and to estimate the infiltration rate for the 45-day recharge pond test. Data was also
collected on pah evaporation, ground-water table response, and potential perched mounding in
the vadose zone. The recharge test was conducted within a test pit with dimensions of 5-ft depth
and 25-ft by 25-ft bottom area, and side slopes of 2.5H:1 V. The water depth in the test pond was
maintained between 29 to 40 inches, but was typically 30 to 36 inches.
The data measurements (BSK, 1996) are summarized in Table 1. From the time that the pond
was filled (to a water depth of 33 inches), the following parameters were calculated using ah
EXCEL spreadsheet (Table 1):
elapsed time (days),
average pond depth (in.),
average flow rate (gal/min),
average evaporation rate (ft/day), and
average infiltration rate (ft/day).
The infiltration rate was determined by dividing the average flow rate by the bottom area of the
test pond plus one-half of the side slope area under water. Because of side slope compaction
during excavation, the contribution of this portion of the pond area to infiltration is uncertain.
The infiltration rate was adjusted for evaporation by multiplying the pan evaporation rate by a
pan coefficient of 0.7 (Hjelmfelt and Cassidy, 1975).
This method of estimating the infiltration rate does not evaluate the effects of horizontal
infiltration through pond sides or alternate pond water depths. As a result, this method of
analysis may slightly overestimate the actual infiltration rate for a larger pond with shallower
-------
SUBJECT
CALCULATION SHEET
Recharge Tat Infiltration Kate & Treatment Float Fond Size
BY Michael Shollty DATE 9/11/96
PROJECT
JOB NUMBER
CALCNO.
SHEET NO.
SHEET REV
ARCSWEST-Selma
20376-034-023
C-O03
4 of 9
0
water depth. Recharge through the pond sides compared to through the pond bottom would be
proportionally less for a larger pond than the test pond size (assuming vertical hydraulic
conductivity is significantly lower than the horizontal conductivity, and neglecting side slope
compaction effects). The infiltration rate for a pond water depth less than the test pond depth of
2.5 to 3 feet would be slightly less, but the reduction is much less than the proportional difference
in head because of unsaturated flow conditions beneath the pond (i.e., mounded water table does
not intercept the recharge pond).
Using this approach, the pond size required for discharge of the treatment plant rate of 300
gal/min was estimated from the approximate steady-state flow rate indicated by the recharge test:
required discharge pond size = 300 gal/min treatment plant discharge rate / (test
pond flow rate / test pond area - evaporation rate), and
test pond area = (25 ft + 33.5 in712 x 2.5) = (32 ft) , where the pond area includes
one-half of the side slopes under water during testing; average pond depth is 33.5
inches, and side slopes are 2.5H:1V.
3. Results
The 45-day recharge test indicated an average flow rate of 6.02 gal/min into the test pond (Table
1). The average evaporation rate was estimated to be 0.03 ft/day. The infiltration rate, adjusted
for evaporation, was estimated to be 1.11 ft/day, based on an infiltration area of 32 ft by 32 ft.
By direct extrapolation of the test results, the required pond bottom dimensions for the treatment
plant discharge of 300 gal/min are 228 ft by 228 ft.
Significant decreases in the flow rate/infiltration rate during the test did not occur, and in fact, the
final rate was slightly higher than during the earlier testing period (Figure 1). A relatively steady
rate of increase in the water table level was indicated to begin about 4 days after starting the test
(Figure 2), but the change (about 1 ft in 45 days) may reflect seasonal variation in the local water
table in combination with water table mounding. The shallow monitoring well (screened 8 to 18
ft bgs) remained dry throughout the test, indicating absence of perched water mounding.
4. Conclusions
Pond bottom dimensions of 200 ft by 260 ft are recommended for recharge of the groundwater
treatment plant discharge. A duplicate pond is recommended to allow continuous operation of
the treatment plant during maintenance activities in one recharge pond. Maintenance activities
are expected because of eventual partial clogging resulting from anticipated progressive
accumulation of fines in the pond bottom. Because the required treatment discharge capacity of
-------
^ CALCULATION SHEET
SUBJECT Recharge Ten Infiltration Kate A Treatment Plant Pond Size
BY.
Michael Sholley DATE 9/11/96
PROJECT
JOB NUMBER
CALCNO.
SHEET NO.
SHEET REV
ARCSWEST - Selma
20376-034-023
C-003
5cf9
0
300 gal/min already includes a 50% contingency beyond the expected full-scale extraction rate of
200 gal/min, additional conservatism in pond dimensions was not warranted.
The infiltration capacity of the constructed ponds must be verified during startup. Activities
during pond construction, such as unintended excessive compaction of the pond bottom during
excavation, could result in infiltration rates different than those estimated from the recharge test.
Such activities which would tend to reduce the infiltration rate are to be avoided.
5. References
Bechtel, 1996, Description of borehole permeability tests and monitor wells for recharge test,
July 1, 1996 (interoffice memorandum from M. Janowiak to M. Sholley and W. Sweet-Dodge).
Bechtel, I995a, Submittal #1 - Evaluation of Full-Scale and Pilot-Scale Groundwater Treatment
Plant and Extraction/Reinjection System Designs, June 16,1995 (letter transmittal to Michelle
Lau from Wileen Sweet-Dodge).
Bechtel, 1995b, Selma Pressure Treating Activity Work Plan, December 1995.
-BSK & Associates, 1996, "Results of Pond Infiltration Test," August 26, 1996 (fax to Bechtel).
Hjelmfelt, A.T., Jr., and J.J. Cassidy, 1975, Hydrology for Engineers and Planners, Iowa State
University Press.
-------
^ CALCULATION SHEET
SUBJECT Kecha^ Tta Infiltration Ratt A Trtatment Plant Poiui Size
BY MichatlSMIfr DATE 9/11/96
PROJECT
JOB NUMBER
CALCNO.
SHEET MO.
SHEET REV
ARCSWEST-Stlma
20376-O34-O23
C-OOJ
6 of 9
0
Table 1 - Recharge Test Data and Results
Field Measurements
Date
9-Jul
9-Jul
9-Jul
9-Jul
9-Jul
9-Jul
9-Jul
9-Jul
9-Jul
9-Jul
9-Jul
9-Jul
9-Jul
9-Jul
9-Jul
9-Jul
9-Jul
9-Jul
9-Jul
10-tal
10-Jul
10-Jul
10-Jul
10-Jul
10-Jul
10-Jul
10-Jul
10-Jul
10-Jul
10-Jul
10-Jul
10-Jul
10-Jul
10-Jul
10-Jul
10-Jul
10-Jul
10-Jul
10-Jul
10-Jul
10-Jul
10-Jul
10-Jul
11-Jul
11-Jul
Time
6:05
7:05
8:10
932
935
11:04
12:11
13:10
14:08
15:05
16:02
1639
18:08
1930
2033
21:00
2139
2238
24:00
038
138
3.-00
4:00
5:00
6:00
730
834
838
10:00
11:03
12:10
1336
1434
1534
16:05
1733
1736
19:00
20:00
2130
2139
2239
24:00
1:01
2:00
Depth
(in.)
.
0.0
14.3
21.0
28.0
31.9
33.1
33.0
33.0
33.0
3X9
3X9
3X9
3X8
323
32.4
323
3X6
32.8
3X8
3X9
33.0
33.0
33.1
333
33.3
333
33.0
33.0
-$2.9--
3X9
3X9
323
3X4
323
323
32.4
32.4
32.4
3X4
3X4
32.3
32.4
32.4
32.4
Flow
(en. ft)
79X580
793.345
794.000
794380
795040
795375
796.048
796.082
796.117
796.150
796.184
796J17
796378
796303
796339
796370
796.418
796.466
796321
796371
796.623
796.678
796.731
796,786
79*841
79*870
79*892
79*912
79*935
79*959
79*985
797.008
797X131
797.058
797.096
797.133
797.168
797313
797350
797390
797327
797367
797,410
797.451
797.493
Depth
to
: Grand- Pan
water EraporadoB
(ft) (in.)
.
-
45.85
-
-
45.86
-
-
-
45.83
-
-
45.82
0
45.85
-
45.88
.
45.89
-
45.89
-
45.89
-
45.91 0.1
-
45.93
-
45.92
O.I
45.89
'
45.88 0.1
.
45.85
-
45.84 O.I
.
45.96
45.99
-
45.99
45.99
-
45.99
Elapsed
Time
(days)
.
-
-
-
-
-
0
0.04
0.08
0.12
0.16
0.20
0.25
038
0.33
0.37
0.41
0.45
0.49
033
037
0.62
0.66
0.70
0.74
0.78
0.83
0.87
0.91
0.95
1.0
1.0
1.1
l.t
1.2
1.2
1.2
1.3
1.3
1.4
1.4
13
1.5
1.5
1.6
Infiltration Eftii
Average
POod
Depth
(In.)
.
-
-
-
-
-
33.1
33.0
33.0
33.0
33.0
33.0
33.0
33.0
3X9
3X9
3X8
32.8
3X8
3X8
32.8
3X8
3X8
3X8
3X9
3X9
3X9
3X9
3X9
3X9
3X9
3X9
3X9
3X9
3X9
3X9
3X8
3X8
3X8
32.8
3X8
3X8
3X8
3X8
3X7
Average
Flow
Batf
(galtain.)
Begin flow
Pond filling
Pond filling
Pond filling
Pond filling
Pond filling
.
43
4.4
4.4
4.4
4.4
4.8
4.7
4.6
4.6
4.7
4.8
5.0
5.1
5.2
53
5.4
53
53
5.4
53
S3
5.1
5.0
4.9
4.8
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.8
ate
Average Avenge
Evaporation Infntntfoa
Rate* Rat*'
(ft/day) (ft/day)
.
-
-
-
-
-
-
0.8
0.8
0.8
0.8
0.8
0.9
0.9
0.9
0.8
0.9
0.9
0.9
. 1.0
1.0
1.0
1.0
1.0
0.01 1.0
1.0
1.0
1.0
0.9
0.01 0.9
0.9
0.9
0.02 0.9
0.9
0.9
0.9
0.02 0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
-------
SUBJECT
CALCULATION SHEET
Recharge Ttn hftitmtio* Knit A Treatment Plant Pond Size
BY Michatl SMolUy DATE 9/11/96
PROJECT
JOB NUMBER
CALC NO.
SHEET NO.
SHEET REV
AKCSWEST-Selma
20376434-023
C-003
7of9
0
Table 1 - Recharge Test Data and Results
Date
I l-Jul
Il-Jul
1 l-Jul
tl-Jul
1 l-Jul
1 l-Jul
Il-Jul
1 l-Jul
1 l-Jul
1 l-Jul
1 l-Jul
Il-Jul
1 l-Jul
1 l-Jul
U-Jul
1 l-Jul
12-Jul
12-Jul
12-Jul
* 13-Jul
13-Jul
14-Jul
15-Jul
16-Jul
17-Jul
19-Jul
22-Jul
24-Jul
28-Jul
3 l-Jul
2-Aug
5-Aug
8-Aug
9-Aug
13-Aug
18-Aug
23-Aug
S-Sep
Time
3:00
349
5:00
6:00
13:00
14:10
15:00
16:00
17:00
18:00
19.-00
20:00
21:00
22.-02
23:05
2349
8:30
11:00
14:30
14:32
16:30
14:36
10:10
10:40
10:30
8:30
18:30
18:31
6:30
14:00
17:02
18:03
1548
14:30
18:20
11:28
13:32
11:00
Field
Pood (
Depth
(In.)
32.4
32.4
32.4
32.4
324
324
324
32J
3X5
324
32.4
32.8
32.4
3X3
32.4
32.4
32.4
32.4
32.5
33.1
33.1
324
38.8
35.8
33.8
324
307
3X5
35 Jr
39.8 -
33S
304)
30.0
29.0
33.3
35.0
384
0.0
MevureiD
^unaUttre
Flow
(Ctt.fl)
797434
797476
797.613
797.651
797.946
797.990
798.020
798.070
798.120
798.150
798.190
798,230
798.270
798.320
798450
798,386
798.755
798.824
799.002
800755
800350
801.408
802481
803,902
804,842
806.771
809,690
811,966
-
82Q£12
.
.
-
828730
-
-
848797
-
eott
Depth
to
Ground-
water 1
(ft)
45.99
45.99
45.95
45.92
45.92
45.92
45.92
45.92
45.92
45.93
45.95
45.98
45.97
45.99
45.99
45.99
45.98
45.89
45.89
45.88
45.86
45.85
45.83
45.80
45.73
45.69
45.63
45.55
4540
45.44
45.33
4570
44.91
44.79
44.45
Pan
EvBpontkm
(In.)
-
-
04
-
-
-
.
-
07
-
.
-
-
-
.
0.2
-
.
0.7
.
04
04
04
04
.1
.4
0.9
.8
.7
.1
.4
14
-
1.8
2.4
27
Ebpted
Time
(dm)
1.6
1.7
1.7
1.7
2,0
2.1
2.1
27
27
27
24-
2.3
2.4
2.4
24
24
2.8
3.0
3.1
4.1
4.2
5.1
5.9
6.9
7.9
9.8
13.3
15.3
18.8
22.1
247
277
307
31.1
35.3
40.0
45.1
.58.0
Infil
Avenge
Pood
Depth
(in.)
3i7
3X7
32.7
32.7
32.7
32.7
32.7
32.7
32.7
32.7
32.7
32.7
32.1
32.6
32.6
32.6
32.6
3X6
3X6
3X6
3X7
3X7
33.1
33.7
33.8
33.7
33.1
3X8
33.0
33.7
34.0
33.7
33.4
337
33.0
33.1
334
tradon Estta
Avenge
Flow
Rate
(raVmin.)
4.8
4.8
4.8
4.8
4.8
4.8
4.8
4.9
4.9
4.9
4.9
4.9
4.9
4.9
4.9
4.9
4.9
4.9
5.0
5.3
54
54
5.7
5.9
5.8
5.7
54
5.4
5.8
5.4
6.02
aate
Avonge
ctaycMiioii
Rate*
(ft/day)
0.02
0.02
0.02
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
M
Avenge
InBhntkM
Rale*
(ft/day)
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
.0
.0
.0
.1
.1
.1
.0
.0
.0
1.1
1.0
1.11
Notes:
* Evaporation rate estimate assumes paa coefficient of 0.7.
Infiltration nte estimate assumes effective area of infiltration during testing of 32 ft x 32 ft
-------
^ CALCULATION SHEET
SUBJECT Recharp Tea Infiltration Kate A Treatment Plant Pond Size
BY Michael SholUy DATE 9/11/96
PROJECT
JOB NUMBER
CALCNO.
SHEET NO.
SHEET REV
AACSWEST Selma
20376434-02J
C-C03
8 of 9
0
Figure 1 - Average Pond Water Depth, Flow Rate, and Infiltration Rate
0
0
10
20 ' 30
Elapsed time, in days
40
0
50
Flow rate (gpm)
Infiltration rate (ft/day) A Pond water depth (inches)
-------
^ CALCULATION SHEET
fl ip.lFPT *tctuuit Tea Infiltration Kali A Treatment Plant Pond Sue
BY Michael SHoUey DATE Ml/96
PROJECT
JOB NUMBER
CALCNO.
SHEET NO.
SHEET REV
ARCSWEST-S*lma
20376434-O23
C-003
9 of 9
0
Figure 2 - Depth to Ground-water Table
44.0
47.0
0
10
20
30
40
50
60
Elapsed time, in days
-------
-------
ATTACHMENT A
USEPA/Selma Pressure Treating Superfund Site
Groundwater Extraction-Recharge Basin/Treatment
Construction Cost Estimate
BEI
November 6, 1996
-------
-------
Job 20376
USEPA/Sclma Pressure Treating Site
Protect Data
Client: USEPA Region IX
San Francisco, California
Work
Assignment: Selma Pressure Treating Superfund She
Location: Selma, California
Estimate The estimate scope includes construction of groundwater extraction system,
Scope: groundwater treatment plant and treated groundwater recharge basin.
A brief description of these three construction hems are;
(A-U Groundwater Extraction System
- Four (4) groundwater extraction wells and pumps
- 2,400 feet of HOPE piping delivering groundwater to treatment plant
- Leak detection system
- Bore/jack steel carrier pipe
Electrical and control
(A-2) Recharge Basin
- Two (2) basins, 200' x 260' each
- 600 feet of PVC piping connecting between treatment plant and basins
- Basin inlet valves & flowmeters in two (2) manholes
- 1,800 feet of cyclone fence and a gate around the basins
(B) Groundwater Treatment Plant
- Sized to treat 300 gpm of extracted groundwater by chemical precipitation,
clarification and filtration.
- Chromium is the contaminant of concern
Type of Order of magnitude construction cost estimate. The Bechtel estimate updates
Estimate: an estimate previously prepared by Weston to reflect the latest design.
Pricing Fourth Quarter 1 996 Price and Wage Level.
Level: The estimate has been escalated to 2Q 1997 at 3% per year.
Purpose of To provide the client with the updated total construction cost for
Estimate: the project. The original estimate was prepared by Weston, Inc. in 1 992.
Construction Project schedule has not been
Schedule:
11/7/96
SELMA.DOC
-------
Job 20376
USEPA/Selma Pressure Treating Site
1.0 General
Selma Pressure Treating Co. is a former wood preserving site, located 15
miles south of Fresno, California. Beginning in 1981, EPA performed
investigations at the site identifying both soil and groundwater contamination.
Chromium is the contaminant of concern. A full scale groundwater
extraction, treatment and reinjection scheme was proposed.
Roy F. Weston, Inc. (Weston) prepared a Remedial Action Design package
based on this scheme and prepared a construction cost estimate in 1992.
Subsequently, the decision was made by EPA to use a recharge basin concept
for the treated-water disposal, instead of reinjection wells.
This estimate package was prepared based on the design modifications made
by Bechtel Environmental, Inc (BEI) which includes use of a recharge basin
instead of reinjection wells, and use of a pressure piping system instead of a
gravity piping system (resulting in the elimination of 2 lift stations).
2.0 Estimate Methodology
This estimate has been prepared by escalating Weston's estimate from 1992 to
1996 and revising it to reflect the current modified scope.
The major cost revisions made on Weston's estimate are:
Groundwater
Extraction
Recharge Basin
Major
Modifications
-Piping
- Lift station
- Reinjection well
- Piping
- Recharging Basin
Weston's
Estimate
4,250 ft
2ea
8 each
6,900 feet
None
This Estima
2,400ft
deleted
Deleted
600 feet
Included
SELMA.DOC
11/7/96
-------
Job 20376
USEPA/Selma Pressure Treating Site
Major Weston's This Estimate
Modification Estimate
Groundwater -Row Rate 500 gpm 300 gpm
Treatment -Storage Tank - No modification
Plant -Piping - Minor modification
-Process Remove Remove total
hexavalant chromium
chromium
- Plot Arrangement - Minor modification
The cost of the Groundwater Treatment Plant has not been adjusted for
this estimate based on the assumption that the cost decrease due to the
lower flow rate may be offset by more sophisticated process equipment
required to meet a more stringent process (removal of total chromium
instead of hexavalant chromium). This assumption may require further
verification by the contractor.
3.0 Estimate Basis
- Estimate pricing is based on 4th quarter 1996 price and wage level.
- Future escalation is included in the estimate at 3% per year.
- The composite direct labor wage included in the estimate is $ 35/hr.
- Material pricing and unit man-hour rates for civil work (recharge basin) are
based on recent Means Construction Cost Data.
- The man-hours required for hazardous waste operator training is included in
the estimate.
- Indirect field cost is included in the estimate at 100% of direct labor.
- Engineering, Procurement and Construction Management cost (EPCM) is
excluded from the estimate per the original Weston estimate.
- Contingency is included in the estimate at 25% per the original Weston
estimate.
11/7/96
SELMA.DOC
-------
Job 20376
USEPA/Selma Pressure Treating Site
4.0 Qualifications and exclusions
- It is assumed that the demolished asphalt and excavated soil for the recharge
basin is not contaminated i.e. no hazardous waste disposal fee.
- It is assumed that the excavated soil can be disposed within 20 miles from the
job site with no fee.
- It is assumed that there will be no dewatering during the excavation of
recharge basins (water table at approximately 34 feet below the excavated
basin).
- Cost of relocation of any underground and above ground utilities is not
expected and therefore excluded.
- Agency oversight cost is excluded.
5.0 Estimate Results
Table 1
Table 2
Construction Cost Estimate for Groundwater
Extraction/Recharge Basin
Construction Cost Estimate for Groundwater Treatment Plant
Attachment A Construction Cost Estimate detail for Recharge Basin
SELMA.DOC
11/7/96
-------
Table 1
USEPA/Sekna Pressure Treating Site
Oroundwatar Extraction/Recharge Basin
const
rucDon MMI csonaie
I Weston Estimate*
Item
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
Scope
Clearing & grubbing
Reflection wel
12" PVC reJnjectton piping
Including deanoute and sumps
4- PVC reinfection piping
Pressurized water system
Wei head piping
Wei vault
Bore/jack steel carrier pipe
Extraction well
4V2" extraction piping
10V6" extraction piping
12"/8" extraction piping
Leak detection system for
extraction system
Uft station 1
Security fencing and gates
Lift station 2
Electrical & control (50 HP)
Not used
Subtotal Construction Cost
round
Total Construction Cost. 4Q 96
Only
1
1
8
4.454
2.419
1
12
12
200
4
2,170
280
1.800
4.250
1
152
1
1
UnK
Is
Is
es
If
If
Is
ea
ea
If
ea
If
If
If
If
Is
If
Is
Is
UnK
Cost
281.475
5,629
23.644
39
11
135.108
6.868
Z815
563
22,518
68
126
169
12
128,353
23
188.025
394,065
* Original Weston's estimate of 1992 escalated to 4Q 96
Total
Cost
281.475
5.629
189.152
173.706
26,609
135.108
82,416
33,780
112,600
90.072
147,560
35.280
304,200
51.000
128,353
3.496
188,025
394,065
2,382,526
595.632
21.842
3.000.0QQ
Estimate for Extraction/Recharge Basin Concept |
UnK
Scope Only UnK Cost
Mobization 1 Is 281,475
Clearing & grubbing 1 Is 5.629
Dett.
8" PVC dass 150 piping 600 If 39
Delete
Delete
Wei head piping 4 ea 6.868
WelvauK 4 ea 2.815
Bore/tock steel carrier pipe 200 If 563
Extraction wen 4 ea 22,518
fOT extraction piping 100 If 68
10"/6T extraction piping 2,300 If 126
Delete
.ask detection system for 2,400 If 12
extraction system
Delete
Delete
Delete
Electrical & control (20 HP) 1 Is 160,000
Recharge basin (see Attach A) 1 I* 800,000
Subtotal Construction Cost
l^riiBttnnamr*! atf ^Wfaf
wU mM lyM IV y ( &ym
round
Total Construction Cost, 4Q 96
- Escalate to 2Q 97 at 3«/yr
Total Construction Cost, 2Q 97
Total
Cost
281,475
5,629
23,400
27,472
11.260
112.600
90.072
6.800
289,800
28,800
160.000
600,000
1.637.308
408,327
53.365
2,100.000
31,500
2.1 31 .500
11/7/96
SELMA-IOLSTabtel
-------
Table 2
USEPA/Selma Pressure Treating Site
Groundwater Treatment Plant
Construction Cost Estimate
Item
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Description
Mobilization
Equalization Tank
Chemical Storage Tank
Dirty Water Tank
Reactor Modules
Plate Separator/Thickener
Sand Filters
Effluent Storage Tanks
Rlter Press
Foundation and Sitework
Pumps and Equipment
Piping and Valves
Electrical and Controls
O & M Trailer
Monitoring/Analysis System
Subtotal Construction Costs
Contingency at 25%
round
Total Construction Cost, 4Q 96*
Total Cost
$
225,180
55,169
81,065
30,399
340,022
263,461
283,727
247,698
90,072
285,979
213,921
90,072
281,475
11,259
45,036
2,544,534
636,133
19,333
3.200.000
* Original Weston's estimate of 1992 escalated to 4Q 96
11/7/96
SELMA-1.XLSTable2
-------
FILE :
DATE:
QTYBY:
EST BY:
J:\COMMON\YJYIM\ARCS\(SELMA-1 JCLSJTtbte 1
04-NOV-96
Attachment A
USEPA/Selma Preaawe TrMting Site
Recharge Baahi
Construction Co«t Estimate
Locaton Sekne. CA
ProducUvty 1.00
Labor Wage 36.00
PAGE
ITEM
10
DESCRIPTION
Rectum Basin. 2 ea. 200* x 2W eidl
DemoHah ndsUna aephal eurteoe, SOff x 25a
RMTWM exMkig bean, ISwxJhx 430" tang
Excavate lor basin No. 1& 2. 20ffx260'x8>l 2 ea
BedcM wth Mod lor beeln No. 1 A 2, Hoot thick
Construct 2 ramp*, ItTw x SOT long each
Construct epMway. 18Vrx401ong
- FMw fabric. lO-xSff
- 6" Reno rrwttreM. KTxSff
. Gabon, yvvWedTntehxiecriono
Mtfto MM wonc, wow
Provkto manhole*. S db x T deep
Construct naw Mrth d»».15V» x J Moh x 1 .000* tono
Provto* new cyclone fence, ff high. 6 ge
Haul A dhpoee demotahed nprwlt end excavated
eol (Olepoee wthki 20 mtee wXh no fee)
Alow for cM work required for level control and
otncr mtoc unw
HazardouewaHe operator traWna. alow
at 8 people, 50 hour* each
Total Direct FMd Cost
Indirect FMd Coat at 100% of Direct Labor Coat
Roundoff
TOTAL THIS PAGE. 4Q 96
QTY
14.000
750
22.222
3.700
500
600
60
20
100
2
1.700
1,800
25.000
1
1
UNIT
ay
cy
cy
cy
cy
af
ay
cy
cy
ea
cy
It
cy
R
R
UNIT COST
EQUIPT
1.40
1.40
0.60
1.20
1.40
1.20
5.30
MATLS
12.00
0.50
10.00
20.00
1,200
2.500
SIC
2.2C
18.0C
MANHOURS
UNIT MH
0.06
0.06
0.02
0.05
0.10
0.05
2.00
0.06
16
0.05
0.06
50
400
TOTAL
45
1.333
74
25
SO
3
40
8
32
85
2,075
50
400
4.218
WAGE
RATES
COSTS IN $
EbUiPT
1.050
31.111
2.220
600
140
2.040
132.500
169,661
MATLS
44.400
250
800
400
2,400
2.500
50,550
LABOR
1,575
46,666
2.590
875
1,750
105
1.400
210
1.120
2.975
72,625
1.750
14,000
147,641
S/C
30.800
32.400
63.20C
TOTAL
$30.800
$2.625
$77.777
$49,210
$1.475
$2.000
$705
$1.800
$35|
$3.520
$5.015
$32.400
$206.125
$4.25C
$14,OOC
$431,052
$147,641
$21.307
$600,000
11/7/96
SELMA-1 XLSAtt-A
-------
-------
-------
------- |