Third Five-Year Review Report for Dakhue Sanitary Landfill ...Long-term protectiveness requires compliance with effective institutional controls. Long-term protectiveness will be ensured

EPA Region 5 Records Ctr.

1111I11111111111111111111111111111111111

317997

Third Five-Year Review Report

for

Dakhue Sanitary Landfill

Hampton Township Dakota County, Minnesota

January 2009

PREPARED BY:

United States Environmental Protection Agency Region 5

Chicago, Illinois

2-2.-- 0 7Approved by: Date: --------

Richard C. Karl, Director Superfund Division u.S. EPA

(THIS PAGE LEFT INTENTIONALLY BLANK)

Five-Year Review Report

Table of Contents

List of Acronyms E-3

Executive Summary E-5

Five-Year Review Summary Form E-6

I. Introduction 1

II. Site Chronology 2

III. Background 3 Physical Character.istics 3 Land and Resource Use 3 History of Contamination 3 Initial Response 3

IV. Remedial Actions 6 Remedy Selection 6 Remedy Implementation 6 System Operation/Operation and Maintenance 8 Institutional Controls 8

V. Progress Since the Last Five-Year Review 10

VI. Five-Year Review Process 11 Administrative Components 11 Community Invo1vement. 11 Document Review 11 Data Review 12 Site Inspection 12

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VII. Technical Assessment 12 Question A: Is the remedy functioning as intended by the decision documents? 12 Question B: Are the exposure assumptions, toxicity data, cleanup levels, and remedial action objectives (RAOs) used at the time of the remedy selection still valid? 12 Question C: Has any other information come to light that could call into question the protectiveness of the remedy? 13 Technical Assessment Summary 13

VIII. Issues 14

IX. Recommendations and Follow-up Actions 14

X. Protectiveness Statement(s) 15

XI. Next Review 16

Figure

Figure 1 Figure 2

Site Location Map Institutional Controls Map

Tables

Table 1 Table 2 Table 3 Table 4 Table 5 Table 6

Chronology of Site Events Annual Systems Operation! O&M Costs Institutional Controls Summary Table Actions Taken Since the Last Five Year Review Issues Recommendations and Follow-up Actions

Appendices

Appendix A Appendix B Appendix C Appendix D

List of Documents Reviewed Five Year Review Advertisement Completed Site Inspection Checklist Site Photos

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List of Acronyms

AOC ARAR CD CERCLA

U.S. EPA MCL Ilg/m3

mg/kg MNA NCP NPL O&M ppb ppm ppm-c PRP RD/RA RIIFS ROD RPM SVOC TCE TCL TDS UAO VOC MPCA

Administrative Order on Consent Applicable or relevant and appropriate requirement Consent Decree Comprehensive Environmental Response Compensation and Liability Act United States Environmental Protection Agency Maximum Contaminant Level Micrograms Per Cubic Meter Milligram Per Kilogram Monitored Natural Attenuation National Contingency Plan National Priorities List Operation and Maintenance Parts Per Billion Parts Per Million Parts Per Million - Carbon Potentially Responsible Party Remedial Design/Remedial Action Remedial InvestigationlFeasibility Study Record of Decision Remedial Project Manager Semi-Volatile Organic Compound Trichloroethylene Toxic Compound List Total Dissolved Solids Unilateral Administrative Order Volatile Organic Compound Minnesota Pollution Control Agency

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Executive Summary

The Dakue Sanitary Landfill Site (the Site) is a 80 acre landfill (only 25 acres were filled) which accepted 1.5 million cubic yards of mixed municipal and industrial solid wastes from October 1, 1971 to May 31,1988. On June 30, 1994, construction completion at the Site was achieved with the signing of the Preliminary Closeout Report. The triggering action for this statutory review is the date ofthe second five year review signature as shown in u.S. EPA's WasteLAN database: February 27,2004. This is the third five-year review for the Site.

The remedy consists of two operable units (OU)s documented in Records ofDecision (ROD) dated June 28, 1991 and June 30, 1993.

The first OU addressed the source of the contamination by containing the on-site wastes and contaminated soil. The function of this OU is to provide a final cover for the Site which is to prevent or minimize groundwater contamination and risks associated with exposure to the contaminated materials.

The second OU consisted of the following major components:

Institutional Controls contained in Dakota County Ordinance No.114 and Minnesota Rules 4725.2000 and 4725.4300 which restrict well development; and Long term groundwater monitoring to: (1) determine the migration of contamination; (2) assess trends in water quality in the Sand and Gravel aquifer; (3) verify that the deep aquifer is not affected; and (4) monitor contaminant levels in Judicial Ditch no. 1.

All components are currently operational, arid are being operated by the State. After issuance ofthe RODs, Minnesota Rules 4725.2000 and 4725.4300 have been repealed and have been replaced by Minnesota Rule 4725.3650. Moreover, a Land Management Plan (LMP) was developed for the Dakhue Landfill during 2004 as required by Minn. Stat. 115B.412, subdivision 9, to provide for protection of the cap. Also, an active gas extraction system replaced a passive system and perimeter fencing has been installed.

OU1 is protective of human health and the environment. The remedy for OU2 is expected to be protective upon attainment of MCLs, and in the interim, exposure pathways that could result in unacceptable risks are being controlled. Based upon the review of annual groundwater monitoring data, other data reviews, and the October 22, 2008 site inspection conducted for this five-year review, there are no current exposures to human health and the environment. The remedy currently protects human health and the environment because the landfill cap, active gas extraction system, groundwater monitoring system, and institutional controls are in place and operating properly; the existing use of the Site property is consistent with the objectives of the RODs; and there is no evidence of unacceptable levels of groundwater contaminants away from the Site property. Long-term protectiveness requires ~ompliance with effective institutional controls. Longterm protectiveness will be ensured by assuring that institutional controls are monitored and enforced by developing long-term stewardship procedures, and consideration be given to additional proprietary controls to prohibit disturbance of the remedy. The site-wide remedy is expected to be protective uponattainment of MCLs.

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Five-Year Review Summary Form

Site name (from WasteLAN): SITE NAME Dakhue Sanitary Landfill

EPA ID rom WasteLAN): MND981191570

State: MN City/County: Dakota

NPL status: J Final I8l Deleted =Other (specify)

Remediation status (choose all that apply): :::::: Under Construction I8l Operating I8l Complete

Construction com letion date: 06/30/1994

Lead agency: D EPA I8l State LJ Tribe [Other Federal Agency

Author name: Thomas G. Williams

Author affiliation: U.S. EPA

Review eriod: Se tember 3, 2008 to December 1, 2008

Date(s) of site ins ection: October 22, 2008

Type of review: I8l Post-SARA 0 Pre-SARA D NPL-Removal only D Non-NPL Remedial Action Site 0 NPL State/Tribe-lead D Regional Discretion

Review number: 0 1 (first) i] 2 (second) I8l 3 (third) D Other (specify)

Triggering action: 0 IJ Actual RA Onsite Construction 0 Actual RA Start o Construction Completion I8l Previous Five-Year Review Report o Other (specify) Record of Decision Signature

Tri gering action date (from WasteLAN): 02/27/2004

Due date (five years after triggering action date): 02/27/2009

Five-Year Review Summary Fonn, cont'd.

Issues:

• The remedy includes leaving contaminated media in place, which does not support unlimited use and unrestricted exposure. Although Ordinance # 114 and MN Rule 4725.3650 provide the County and the State, respectively, with authority to restrict well development at the site and a Land Management Plan has been developed to preclude disturbance of the landfill cover, additional proprietary controls should be considered to restrict future development of the site.

• Ownership of the Site is in dispute. The ownership issue needs to be resolved and consideration should be given to placing an environmental restrictive covenant (restricting use of the site) on the Site.

• An easement should be placed on the property to ensure that U.S. EPA and the State retain the right to carry out future response actions in the event the property is transferred. Moreover, because MN Rules 4725.2000 and 4725.4300 have been repealed, consultation

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with MPCA should occur concerning whether public notice should be provided concerning the modifications to the ROD requirements resulting from the enactment ofMN Rule 4725.3650 and installation ofthe active gas extraction system and perimeter fencing.

• Long-term stewardship which includes maintaining monitoring and enforcing effective institutional controls must be assured.

Recommendations and Follow-up Actions:

• Discussions should be commenced with MPCA to discuss what additional land use controls on the property may be necessary. In addition, consideration should be given to provide public notice of the modifications of the ROD requirements referred to above.

• Resolve ownership of the Site that is currently in dispute.

• Consultation with MPCA should occur concerning whether public notice should be provided concerning the modifications to the ROD requirements resulting from the enactment ofMN Rule 4725.3650 and installation of the active gas extraction system and perimeter fencing.

• Develop a Long-Term Stewardship Plan or update the O&M Plan to oversee and monitor institutional controls to ensure long-term stewardship. This may include developing and implementing a communication strategy with appropriate state/local governmental agencIes.

Protectiveness Statement:

OUI is protective ofhuman health and the environment. The remedy for OU2 is expected to be protective upon attainment ofMCLs, and in the interim, exposure pathways that could result in unacceptable risks are being controlled. Based upon the review of annual groundwater monitoring data, other data reviews, and the October 22,2008 site inspection conducted for this five-year review, there are no current exposures to human health and the environment. The remedy currently protects human health and the environment because the landfill cap, active gas extraction system, groundwater monitoring system, and institutional controls are in place and operating properly; the existing use of the Site property is consistent with the objectives of the RODs; and there is no evidence of unacceptable levels of groundwater contaminants away from the Site property. Long-term protectiveness requires compliance with effective institutional controls. Long-term protectiveness will be ensured by assuring that institutional controls are monitored and enforced by developing long-term stewardship procedures, and consideration be given to additional proprietary controls to prohibit disturbance of the remedy. The site-wide remedy is expected to be protective upon attainment of MCLs.

Date of last Regional Review of Human Exposure Indicator: 912812006 Human Exposure Survey Status: Current Human Exposure Controlled and Protective Remedy in Place Date of last Regional review of Groundwater Migration Indicator: 6/07/07 Groundwater Migration Survey Status: Contaminated Groundwater Migration Under Control Ready for Reuse Determination Status: SWRAU on TBD

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Five-Year Review Report

I. Introduction

The purpose of a five-year review is to determine whether the remedy at a site is protective of human health and the environment. The methods, findings, and conclusions of reviews are documented in Five-Year Review reports. In addition, Five-Year Review reports identify issues found during the review, if any, and recommendations to address them.

The Agency is preparing this five-year review pursuant to CERCLA §121 and the National Contingency Plan (NCP). CERCLA §121 states:

If the President selects a remedial action that results in any hazardous substances, pollutants, or contaminants remaining at the site, the President shall review such remedial action no less often than each five years after the initiation ofsuch remedial action to assure that human health and the environment are. being protected by the remedial action being implemented. In addition, if upon such review it is the judgment of the President that action is appropriate at such site in accordance with section [104] or [106], the President shall take or require such action. The President shall report to the Congress a list offacilities for which such review is required, the results ofall such reviews, and any actions taken as a result ofsuch reviews.

The agency interpreted this requirement further in the National Contingency Plan (NCP); 40 C.F.R. § 300,430(f)(4)(ii) states:

If a remedial action is selected that results in hazardous substances, pollutants, or contaminants remaining at the site above levels that allow for unlimited use and unrestricted exposure, the lead agency shall review such action no less often than every five years after the initiation of the selected remedial action.

The United States Environmental Protection Agency (U.S. EPA) Region 5 has conducted a five-year review of the remedial actions implemented at the Site, located in Dakota County, Minnesota. This statutory review was conducted by the Remedial Project Manager (RPM) from September 3,2008 to October 22,2008. This report documents the results of the review.

This is the third five-year review for the Site. The triggering action for this statutory review is the date of the second five year review signature as shown in U.S. EPA's WasteLAN database: Febmary 27, 2004. This review is required because certain response actions are ongoing and hazardous substances, pollutants, or contaminants are or will be left on site above levels that allow for unlimited use and unrestricted exposure.

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II. Site Chronology

Table 1: Chronology of Site Events

Event Date

Proposal to the NPL 10/2611989

Removal Assessment 8109/1990

NPL listing 8/30/1990

PRPSearch 12/30/1987

RIIFS complete for OU1 3/31/1991

RIIFS complete for OU2 3/31/1993

ROD signature for OU1 6/28/1991

ROD signature for OU2 6/30/1993

Remedial action start for OU1 6/2311992

Remedial action complete for OU1 3/30/1993

Remedial action start for OU2 8/1111993

Remedial action complete for OU2 9/09/1993

Preliminary Close Out Report 6/30/1994

Deletion from NPL 7/2411995

First five-year review 3/2511999

Second five-year review 2/27/2004

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III. Background

Physical Characteristics

The Site is located approximately 6 miles north of Canon Falls, Minnesota, 30 miles south of St. Paul, Minnesota. The Site is located in Section 24 and 25 Township 113 North, Range 18 West, in Hampton Township, Dakota County, Minnesota. See Figures 1 and 2.

Land and Resource Use

The Site is located within the Rochester Till Plain Physiography region of Minnesota. The area of the landfill is associated with a topographic ridge trending northwest-southeast across the Site. At the southern edge of the landfill the topographic ridge ends abruptly forming a series of gullies which drain into a dry creek bed. Farther to the east and south of the landfill the telTain is relatively flat, composed of open and cultivated fields.

The adjacent land is used primarily for agriculture with some residential plots intermixed.

History of Contamination

The Site is an 80 acre landfill (only 25 acres were filled). The landfill accepted an estimated 1.5 million cubic yards of mixed municipal and industrial solid wastes from October 1, 1971 to May 31, 1988. The landfill was used for the disposal of mixed municipal and commercial waste and small amounts of industrial waste. The landfill was open on a part-time basis until 1973, when operations were extended to six days a week. The exact quantity and disposal area of hazardous substances is unknown. The area surrounding the site consists mainly of single family dwellings or farms. Residential drinking water supply wells, municipal water supply wells, and irrigation wells draw groundwater from a shallow aquifer and from the hydraulically connected aquifers beneath it. Approximately 650 people use the aquifer as their primary source of drinking water within a three-mile radius of the site, and about 6,600 acres of major cropland are ilTigated with water from the aquifer. Pine Creek, located three-quarters of a mile south of the site, and the Cannon River, located 2.75 miles south of the site, are used for recreational purposes.

Results from the analysis of monitoring well samples document the presence of a variety of compounds within the plume on Site. The most common of these compounds are benzene, methylene chloride, cis-trans 1,2, dichloroethene, ethyl ether, tetrahydrofuran and thrichloroethene. Residential wells near the Dakhue Sanitary Landfill were sampled by Minnesota Pollution Control Agency (MPCA) staff on several separate occasions. The samples were analyzed for volatile organic compounds (VOCs) by the Minnesota DepaItment of Health (MDH). None of the residential wells samples were known to be contaminated.

There is no discrete source of contamination other than mixed municipal waste at the Dakhue Sanitary Landfill. Most of the waste that was present at the landfill was household trash and garbage. A small quantity of industrial and commercial waste was disposed of at this site. The chemicals detected at the site are consistent with some of the waste streams paint and solvents thought to have been disposed of in the landfill.

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Initial Response

The U.S. EPA funded the MPCA to conduct Remedial Investigation (RI) and Feasibility Study (FS) activities. RI work involves determining the nature and extent of contamination and FS work involves developing and evaluating remedial alternatives. During the course of those activities, U.S. EPA and MPCA decided to divide the remedy for the Site into two units or discrete actions, referred to as "operable units" (OUs). They are as follows:

OU One: Source control of contaminates from the landfill. au Two: Contaminated groundwater migration management.

A focused FS was completed in March 1991 for the first OU and a Record of Decision (ROD) was issued on June 28, 1991 outlining work necessary to address the source of the contamination, wastes disposed in the landfill itself.

A RI was completed for the second OU in August 1992 and a FS was completed on March 31,1993. A ROD was issued on June 30, 1993 outlining work necessary to address the potential migration of contaminated groundwater.

Basis for Taking Action

Twelve carcinogens were detected at the Site in the groundwater. In a residential use setting, the excess cancer risk associated with ingestion of water was estimated to be 6 x 10-4

.

Eleven of the following carcinogens were detected at concentrations greater than 1 x 10-6.

Groundwater

Carbon Tetrachloride Chloroform Methylene chloride 1,1,1- Trichloroethane 1,1,2- Trichloroethane 1,1-Dichloroethane 1,1-Dichloroethene 1,1,2,2-Tetrachloroethene Toluene Chlorobenzene Xylenes

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IV. Remedial Actions

Remedy Selection

On June 28, 1991, EPA issued a Record of Decision (ROD) which documented remedial actions for OU 1 (source control). The first operable unit addresses the source of the contamination by containing the wastes and contaminated soil on site. The function of this operable unit is to provide a final cover for the Dakhue Sanitary Landfill which will prevent or minimize groundwater contamination and risks associated with the exposure to the contaminated materials. The major components of the selected remedy for this operable unit include: Capping with a final cover system consisting of a gas control layer, a barrier layer of low permeable material, a drainage layer, topsoil cover and vegetation.

EPA issued the ROD for the second operable unit on June 30,1993, and includes the following components. The institutional controls contained in Dakota County Ordinance No. 114 and Minnesota Rules 4725.2000 and 4725.4300 which restricted well development. A long-term groundwater monitoring program to: (1) ensure that contaminated groundwater is not migrating off-site; (2) assess trends in water quality in the Sand and Gravel aquifer; (3) verify that the deep aquifer is not affected: and (4) provide adequate protection to aquatic life in Judicial Ditch No.1 from adverse effects resulting from possible discharge of contaminated groundwater.

Remedy Implementation

Final construction of the landfill cover under OU one at Dakhue started on June 24, 1992. The work included construction of approximately 28 acres of final cover over the landfill. The landfill cover consisted of a gas vent system, a barrier layer of geosynthetic clay liner and geomembrane, subsurface drainage, and cover soils with vegetation. Construction activities occurred from June 24, 1992 until the completion of the final cover and site restoration on October 21, 1992. All final cover construction activities at the Dakhue landfill have been completed. All components of the final cover system are operational and functional.

An inspection of the Site was conducted in the spring of 1993, which verified that the final vegetative cover had been established on the landfill. On March 29, 1993, Barr Engineering submitted a Remedial Action Report documenting successful completion of construction activities. The report documents and discusses the construction of the 28 acre final landfill cover, surface water controls which included a sedimentation basin, and a site access road. The final cover consists of a gas vent system, a barrier layer of geosynthetic clay liner and geomembrane, subsurface drainage, and cover soils with vegetation.

In addition, 13 groundwater monitoring wells were installed for the long-term groundwater monitoring system under OU two. The installation and development of the wells at the Site were completed the week ending August 13, 1993. The first round of sampling was completed the week ending August 26,1993. Monitoring of groundwater will continue on a long term basis. Presently, 13 groundwater monitoring wells are sampled three times per year to evaluate the impact of the final cover. This sampling is done under direction of the MPCA. Long term operation and maintenance of the landfill cover continues to be performed under the direction of the MPCA.

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The Site achieved construction completion with the signing of the Preliminary Close Out Report on June 30, 1994. The Site was deleted from the NPL on July 24, 1995. A Five Year Review was issued for the Site on March 25,1999. A second Five Year Review was issued on February 27, 2004.

Since issuance of the RODs, Minnesota Rules 4725.2000 and 4725.4300 have been repealed and have been replaced by Minnesota Rule 4725.3650. In addition, an active gas extraction system replaced a passive system and perimeter fencing has been installed.

A Land Management Plan (LMP) was developed for the Dakhue Landfill during fiscal year 2004 as required by Minn. Stat. 115B.412, subd. 9. The purpose of the LMP is to protect the integrity of the landfill's remediation systems, help protect the health and safety of persons involved with activities at the landfill, and accommodate local government needs and desires for land use with consideration for public health and safety. The MPCA worked closely with Hampton Township and recommended the Township adopt a new zoning district and ordinance specific to the permitted property. This district, called Closed Landfill Restricted, does not allow any permitted uses within the district but allows conditional uses that are approved by the MPCA Commissioner and Hampton Township. Also, the MPCA recommended the Township adopt a setback ordinance around the landfill permitted boundary to not allow structures to be built within 100 feet of the boundary on the north, east, and west sides, and within 200 feet of the boundary along the south side.

System Operation/Operation and Maintenance

Long term operation and maintenance of the landfill cover, active gas extraction system, and groundwater monitoring wells are being conducted by MPCA. Presently, 13 groundwater monitoring wells are sampled three times per year (spring, summer and fall events) to evaluate groundwater contamination. This sampling is done under the direction of the MPCA.

Table 2: Annual System Operations/O&M Costs Dates

Total Cost rounded to nearest $1,000 From To

Julv 2003 June 2004 21,000

July 2004 June 2005 74,000

Julv 2005 June 2006 55,000

July 2006 June 2007 60,000

July 2007 June 2008 64,000

Institutional Controls

Institutional Controls are non-engineered instruments, such as administrative and/or legal controls, that help minimize the potential for exposure to contamination and protect the integrity of the remedy. Compliance with institutional controls is required to assure long-term protectiveness for any areas which do not allow for unlimited use or unrestricted exposure (UUIVE).

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The table below summarizes the institutional controls for those restricted areas.

PhIVSlcaIArea- summary Table 3 Map of Media, Engineered Controls, & Areas that Do Not Support UUlUE Based on Current Conditions. Landfill Cap

Groundwater

IC Objective in Decision Document

Physical Area covered by Implemented Institutional Control

Prohibit interference with landfill cap.

Institutional control objective applies to and covers the landfill and surrounding area in Figure 2.

Prohibit groundwater use. Current area that exceeds groundwater cleanup standards are identified in the 2006 Annual Report .

All Non-UUIUE areas are addressed effectively by institutional controls as determined by the institutional controls evaluation activities which are discussed below. A Land Management Plan (LMP) was developed for the Dakhue Landfill during fiscal year 2004 as required by Minn. Stat. 115B A12,subd. 9. The purpose of the LMP is to protect the integrity of the landfill's . remediation systems, helps protect the health and safety of persons involved with activities at the landfill, and accommodate local government needs and desires for land use with consideration for public health and safety. Also, ordinance # 114 and MN Rule 4725.3650 provide the County and the State, respectively, with authority to restrict well development at the site. The Site is managed by the MPCA who has placed limitations on the use of the Site. For now the Site is used as open space with a prairie, woodland or a combination environment and for scientific and/or ecological study relating to the management of reclaimed landfills. No public use of the Site is allowed. The MPCA worked closely with Hampton Township and recommended the Township adopt a new zoning district and ordinance specific to the permitted property. The district, called Closed Landfill Restricted, would not allow any permitted uses within the district but allows conditional uses that are approved by the MPCA Commissioner and Hampton Township. Also, the MPCA recommended the Township adopt a setback ordinance around the landfill permitted boundary to not allow structures to be built within 100 feet of the boundary. The ordinance was adopted by the Hampton Township Board of Supervisors on July 20th 2004. See Figure 2.

The holder of title to the permitted property at the Dakhue Landfill is the State of Minnesota, although the County will not allow the State to record the deed due to a dispute as a result of a tax issue. Discussions between the State and Dakota County are ongoing to resolve the Issue.

In addition, as discussed below, the development of long-term stewardship procedures and adoption of additional proprietary controls will ensure that effective institutional controls are maintained and monitored. Maps which depict the current conditions of the Site and the areas which do not allow for UUIUE will be developed as part of the Long-Term Stewardship Plan discussed below.

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Current Compliance

Based on inspections and interviews, U.S. EPA is not aware of any uses of the Site, including groundwater uses, which are inconsistent with the objectives which will be served by the institutional controls. No one is being exposed to Site-related contaminants. There are no drinking water supply wells installed within the impacted groundwater area. The Site has been fenced to restrict and prohibit access and the Site is inspected to ensure that the cap is not damaged. Also, groundwater restrictions appear to be functioning as intended. Long-term compliance with institutional controls will be accomplished by preparing a monitoring plan which will include various activities such as mapping, and by providing for long-term stewardship of the Site, which includes maintaining and monitoring effective institutional controls. Consideration should be given to additional proprietary controls.

Long-Term Stewardship Plan

Since compliance with the institutional controls is necessary to assure the protectiveness of the remedy, planning for long-term stewardship is required. Long-term stewardship involves assuring effective procedures are in place to properly maintain and monitor the site. Long-term stewardship will ensure effective institutional controls (lCs) are maintained and monitored and that the remedy continues to function as intended with regard to the institutional controls. A LongTerm Stewardship Plan shall be developed, or the O&M plan updated, that includes procedures to ensure long-term institutional controls stewardship such as regular inspection of institutional controls at the Site and certification to U.S. EPA that the institutional controls are in place and are effective.

Landfill Cover O&M

Operation and maintenance of the landfill cover system includes inspection of the landfill surface, vegetation conditions, and surface water drainage features. Inspections of the landfill cover are performed twice a year.

V. Progress Since the Last Review

Table 4: Actions Taken Since the Last Five-Year Review

Issues from Previous Review

Recommendations! Follow-up Actions

Party Responsible

Milestone Date

Action Taken and Outcome

Date of Action

The Site required an active gas extraction system

Installation of an active gas extraction system

PRP 1112003 Extraction System Installed

1112003

New fencing required installation.

Install Fence PRP 2004 Fence Installed 2004

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Protectiveness Statement from Last Review

The remedy is protective in the short term of human health and the environment. All immediate threats at the site have been addressed. All threats at the Site have been addressed with Site capping, the gas collection system, groundwater monitoring, and institutional controls.

Long term protectiveness of the remedial action will be verified by conducting site monitoring of groundwater, surface water and the landfill.

Status of Recommendations and Follow-Up Actions from Last Review

The MPCA replaced the Dakhue Landfill passive gas venting system and upgraded to an active gas extraction system to remediate landfill gas migration and remove additional VOCs from the waste before it can leach into the groundwater. The upgrade consists of 25 new vertical gas extraction wells and connecting the wells with a buried pipe system that terminates at a new blower/flare skid. The landfill gas is combusted in a new enclosed flare capable of destroying at least 98% of the VOCs that are present in the gas (See Appendix D, Site Photos). Two new double walled underground gas condensate tanks will be installed to collect landfill gas condensate. The condensate is pumped as needed and hauled to a municipal wastewater treatment facility for proper treatment and disposal. The existing passive gas venting system was removed and the landfill cover barrier geomembrane patched to prevent water and air infiltration into the waste mass. A property boundary fence was installed as part of this project.

Results of Implemented Actions, Including Whether They Achieved the Intended Effect

As discussed above the passive gas venting system was replaced with an active gas extraction system to remediate landfill gas migration and remove additional VOCs from the waste before it can leach into the groundwater. A property boundary fence was installed as part of this project. Groundwater quality has improved significantly, likely from the installation of the active gas extraction system.

VI. Five-Year Review Process

Administrative Components

MPCA was notified of the initiation of the five-year review on September 3, 2008. The Dakhue Sanitary Landfill Five-Year Review was led by Tom Williams of the U.S. EPA, Remedial Project Manager for the Site and Don DeBlasio, Community Involvement Coordinator (CIC). Joe Julik, of the MPCA, assisted in the review as the representative for the MPCA.

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The review, which began on September 3,2008, consisted of the following components:

Community Involvement; Document Review; Data Review; Site Inspection; and, Five-Year Review Report Development and Review.

Community Involvement

Activities to involve the community in the five-year review were initiated with a meeting in late 2008 between the RPM and CIC for the Site. A notice was published in the local newspaper, the Shopper and Beacon on November 24th and the 2i\ 2008 respectively, stating that there was a fiveyear review and inviting the public to submit any comments to U.S. EPA. No comments were received from the public. The results of the review and the report will be made available at the Site information repository located at Minnesota Pollution Control Agency, 520 Lafayette Road North, S1. Paul, MN.

Document Review

This five-year review consisted of a review of relevant documents including O&M records and monitoring data (Appendix A), and applicable soil and groundwater cleanup standards, as listed in the ROD, were also reviewed.

Data Review

Groundwater

Groundwater quality has dramatically increased since the last the last Five- Year Review when seven contaminants exceeded their MCLs. A sampling event performed in the summer of 2006 resulted in MCL exceedances of arsenic and nitrate+nitrite as nitrogen only at concentrations of 17 ppb and 11 ppb respectively. Further, nitrate+nitrite may not be a site contaminant. The MCL for arsenic is 10 Ilg/L and the Health Risk Limit (HRL) for nitrate+nitrite as nitrogen is 1011gIL. Groundwater sampling performed in 2007 and 2008 had similar results with minor exceedances of both contaminants. This is indicative of continued improvements to groundwater quality beneath and down gradient of the Dakhue Landfill.

Site Inspection

The inspection at the Site was conducted on October 22, 2008. In attendance was Tom Williams. The purpose of the inspection was to assess the protectiveness of the remedy, including the presence of fencing to restrict access, the integrity of the landfill cover, and general condition of the LFG extraction system.

The Site in general was in very good condition and undisturbed. No new uses of groundwater were observed. The lock and fences were in good condition. The vegetative cover was in very good condition with no bare spots or stressed vegetation observed.

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VII. Technical Assessment

Question A: Is the remedy functioning as intended by the decision documents? Yes

The review of documents, ARARs, risk assumptions, and the results of the Site inspection indicates that the on-site equipment is functioning as intended by the ROD. There have been no changes in the physical conditions ofthe Site that\would affect the protectiveness of the remedy. There have been no changes in the toxicity factors for the contaminants of concern that were used in the health assessment, and there have been no changes to the standardized health assessment methodology that could affect the protectiveness of the remedy. There is no other information that calls into question the protectiveness of the remedy.

Institutional controls are in place. Disruption of the cap through well development is prohibited because the Site is operated by MPCA and Dakota County Ordinance No. 114 and MN Rule 4725.3650 regulates the construction, operation, maintenance, repair, sealing, and permitting of all wells within Dakota County. In addition, the LMP developed for the site and Hampton Township ordinances restrict the ability to develop the site in such a way as to disturb the landfill cover, active gas extraction system, and groundwater monitoring wells.

Question B: Are the exposure assumptions, toxicity data, cleanup levels, and remedial action objectives (RAOs) used at the time of remedy selection still valid? Yes

There have been no changes in the physical conditions of the Site that would affect the protectiveness of the remedy. The institutional controls restrict the property and groundwater uses at the Site.

Changes in Standards

The MCL standard for arsenic was changed from 50 Ilg/L to 10 Ilg/L. All of the ARARs for groundwater, with the exception of arsenic, and nitrate + nitrite nitrogen have been met. The chemical specific ARARs for groundwater are the Minnesota Department of Health (MDH) Health Risk Limits (HRL)s, Federal Safe Drinking Water Act MCLs, 40 C.F.R. § 141.1116; Maximum Contaminant Level Goals (MCLGs) in 40 C.F.R. § 141.50-51, and Secondary MCLs in 40 C.F.R. § 143.3. There have been no other changes in these ARARs and no new standards or TBCs affecting the protectiveness of the remedy have been adopted.

Changes in Exposure Pathways, Toxicity, and other Contaminant Characteristics

The exposure assumptions used to develop the Human Health Risk Assessment included both current exposures and potential future exposures for recreational users, trespassers, employees, and off-site residents. There have been no changes in the toxicity factors for the contaminants of concern that were used in the baseline risk assessment. These assumptions are considered to be conservative and reasonable in evaluating risk and developing risk-based cleanup levels. No change to these assumptions or the cleanup levels developed from them is warranted. There has been no change in the standardized risk assessment methodology that could affect the protectiveness of the remedy.

11

Question C: Has any other information come to light that could call into question the protectiveness of the remedy? No

The RODs determined that there appears to be little risk to ecological communities and or populations in those communities at the Site from organic chemicals in environmental media at the Site. No weather related events have affected the protectiveness of the remedy. There is no other information that calls into question the protectiveness of the remedy.

Technical Assessment Summary

According to the data reviewed, the Site inspection, the remedy is functioning as intended by the RODs. There have been no changes in the physical conditions of the site that would affect the protectiveness of the remedy. All ARARs cited in the OU two ROD have been met, with the exception of the two exceedances of arsenic, and nitrate + nitrite nitrogen based on the 2006 Annual Report. There have been no changes in the toxicity factors for the contaminants of concern that were used in the baseline risk assessment, and there have been no changes to the standardized risk assessment methodology that could affect the protectiveness of the remedy. There is no other information that calls into question the protectiveness of the remedy.

VIII. Issues

The following issues are noted but do not affect the protectiveness of the remedy. The remedy includes leaving contaminated media in place, which does not support unlimited use and unrestricted exposure. Although Ordinance # 114 and MN Rule 4725.3650 provide the County and the State, respectively, with authority to restrict well development at the site and a Land Management Plan has been developed to preclude disturbance of the landfill cover, additional proprietary controls should be considered to restrict future development of the site. At this point, recording of the deed is in dispute. The recording of the deed issue needs to be resolved and consideration should be given to placing an environmental restrictive covenant (restricting use of the site) on the Site. In addition, an easement should be placed on the property to ensure that u.S. EPA and the State retain the right to carry out future response actions in the event the property is transferred. Moreover, because MN Rules 4725.2000 and 4725.4300 have been repealed, consultation with MPCA should occur concerning whether public notice should be provided concerning the modifications to the ROD requirements resulting from the enactment ofMN Rule 4725.3650 and installation of the active gas extraction system and perimeter fencing.

Table S- Issues-

Issues

Affects Current

Protectiveness (YIN)

Affects Future Protectiveness

(YIN)

Long-term stewardship which includes maintaining and monitoring effective institutional controls must be assured

N Y

12

IX. Recommendations and Follow-up Actions

The following follow up actions are noted but do not affect the protectiveness ofthe remedy. Discussions should be commenced with MPCA to discuss the issue with regard to recording of the deed for the Site and what additional land use controls on the property may be necessary. In addition, consideration should be given t6 provide public notice of the modifications of the ROD requirements referred to above.

Table 6: Recommendations and Follow-up Actions

Issue

Recommendations and Follow-up

Actions Party

esponsible Oversight

Agency Milestone

Date

Mfects Protectiveness

(YIN)

Current Future

Long-term Develop a PRPs U.S. EPA 1/31/09 N Y stewardship Long-Term which includes Stewardship maintaining Plan or update monitoring the O&MPlan and enforcing to oversee and effective monitor institutional institutional controls must controls to be assured ensure long

term stewardship. This may include developing and implementing a communication strategy with appropriate state/local governmental agencIes.

13

X. Protectiveness Statement

OUI is protective of human health and the environment. The remedy for OU2 is expected to be protective upon attainment ofMCLs, and in the interim, exposure pathways that could result in unacceptable risks are being controlled. Based upon the review of annual groundwater monitoring data, other data reviews, and the October 22, 2008 site inspection conducted for this five-year review, there are no current exposures to human health and the environment. The remedy currently protects human health and the environment because the landfill cap, active gas extraction system, groundwater monitoring system, and institutional controls are in place and operating properly; the existing use of the Site property is consistent with the objectives of the RODs; and there is no evidence of unacceptable levels of groundwater contaminants away from the Site property. Long-term protectiveness requires compliance with effective institutional controls. Long-term protectiveness will be ensured by assuring that institutional controls are monitored and enforced by developing long-term stewardship procedures, and consideration be given to additional proprietary controls to prohibit disturbance of the remedy. The site-wide remedy is expected to be protective upon attainment of MCLs.

XI. Next Review

The next five-year review for the Dakhue Sanitary Landfill Site is required within five years from the signature date ofthis review.

14

FIGURE 1

Superfund Site Location U.S. Environmental Protection Agency

Dakhue Sanitary Landfill Dakota County, MN

/1

! ')

\ Wisconsin St. Paul <

Minne.sota ~~ "---\

l--------:-----------' ~~~d~c;1 g~;i~~e 5~~I~ctober 27 2008 I ImageDate-20Q4 . I _____.. ._.. ~_. __.._ _ __ . J

N

+

3

MND981191570

DAKOTA r:::1 ~I:ID

® GO·ODHUE

County

Site

15

FIGURE 2

Institutional Control (IC) Review Superfund Map Depicting Required and U.S. Environmental Protection Agency Implemented Institutional Controls

Dakhue Sanitary Landfill Dakota County, MN MND981191570

410 820 ___===,Feeto N

+o Setback Ordinance - 100ft·

Legend

r;::] ~ko~ Cou';!\>: Ordinance No. 114 (1988~ - Required and Jmpiemented IC a~~r~lfringt~ i'~~~~~~in°~=ntou~wenance. repaIr. sealing.i.:. Site Boundary/Fence -Access Control

o landfill Cap· Required and Implemented Ie -Disruption of cap prohibited

~ Setback Ordinance - 200 ft'

'See Hampton Township Dakhue Landfill Ordinance (2004), Attachment B Crt!at2d by Julie S&hilt

EPA Disclaimer: Please be advised that areas depided in the map have been estimated. The map does U.S. EPA ReviDn 5 en 12/1612C08 not: create any rights enforceable by any party. EPA may refine ()( change this data and map at any time. Image Date: 2OD8

16

APPENDIX A

Documents Reviewed

MPCA, "Dakhue Sanitary Landfill Annual Report 2006".

U.S. EPA, "Second Five-Year Review, Dakhue Sanitary Landfill" February 27, 2004.

U.S. EPA, "Five-Year Review, Dakhue Sanitary Landfill" March 2,1999.

U.S. EPA, "Record of Decision, Operable Unit 2, Dakhue Sanitary Landfill", September 30, 1993.

U.S. EPA, "Record of Decision, Operable Unit 1, Dakhue Sanitary Landfill", June 28, 1991.

17

APPENDIXB

EPA Starts Third Five-year Review of Dakhue Sanitary Landfill

Hampton Township, Minnesota

U.S. Environmental Protection Agency is starting the third five-year review of the Dakhue Sanitary Landfill, Superfund site, 260th Street East and Hogan Avenue, Cannon Falls, Minn. The Superfund law requires regular checkups of sites that have been cleaned - with waste managed onsite - to make sure the cleanup continues to protect people and the environment.

EPA's cleanup of benzene, lead, PCE (perchloroethylene), TCE (trichloroethylene), toluene and volatile organic chemicals included installation of an erosion control system, capping and a landfill gas extraction system currently in operation. Twelve monitoring wells are sampling to evaluate the effectiveness of the control measures.

EPA expects to have the review completed by late Febmary. The five-year review is an opportunity for you to tell EPA about site conditions and concerns you have. Site information is available at Minnesota Pollution Control Agency, 520 Lafayette Road N., St. Paul, and on the Web at www.epa.gov/superfund/sites/npllnar674. You may call Region 5 toll-free at 800-621-8431,8:30 a.m. - 4:30 p.m., weekdays. Contact:

DOll de Blasio Thomas Williams Community Involvement Remedial Project Manager Coordinator EPA Region 5 (SR-6J) EPA Region 5 (P-19J) 77 W. Jackson Blvd. 77 W. Jackson Blvd. Chicago, IL 60604 Chicago, IL 60604 312-886-6157 312-886-4360 williams. [email protected]. [email protected]

18

http://www.epa.gov/superfund/sites/npl/nar674

mailto:[email protected]

mailto:[email protected]

APPENDIXC

Completed Site Inspection Checklist with Detailed Annual Systems Operations/O&M Costs

OSWER No. 9355.7-03B-P

Please note that "O&M" is referred to throughout this checklist. At sites where Long-Term Response Actions are in progress, O&M activities may be referred to as "system operations" since these sites are not considered to be in the O&M phase while being remediated under the Superfund program.

Five-Year Review Site Inspection Checklist (Template)

(Working document for site inspection. Information may be completed by hand and attached to the Five-Year Review report as supporting documentation ofsite status. "NtA" refers to "not applicable. ")

I. SITE INFORMATION Lo'\NbI'/LL

Site name: V L1 v 1-1 v r- c:- b Date of inspection: /p!z;1-lo'B7,<\10;'-1

Lo<ationandRegion: C'1I,.1rJo.) {.~J,. ...H ~ EPAID: NtJD"7t!>/ /"11 ~70

Agency, office, or company leading the live-year Weatherltemperj;re: S;Zt>review: O>J!3Il!.CftST (,.pAINt).S,t'-'P1Cl.

/Remedy Includes: (Check all that apply)

G Landfill COVel/containment G Monitored natural attenuation G Access controls G Groundwater containment G Institutional controls G Vertical barrier walls G Groundwater pump and treatment G Surface water collection and treatment G Other

AttachmentS: G Inspection team roster alt.ched G Site map attached

II. INTERVIEWS (Check all that apply)

1. O&M site manager J" t -Iu L/ "- Ii 'fz>ao£ EOLo? 1ST 9ht/log Name Title Dale

Interviewed G at site ~ by phone Phone no. ,f'/· 29(" - "$ 'IS"t/ Problems, suggestions; G Report attached "v"rJ r-.

2. O&M staff Name Title Dale

Interviewed G at site G at office G by phone Phone no. Problems, suggestions; G Report attached

D-7

19

----

----

----

----

OSWER No. 9J55.7·OJB·P

3. Local regulatory authorities and respon.e agencies (i.e., State and Tribal offices, emergency response oflice, police departmenl, office of public health or environmental health, zoning oflice, recorder of deeds, or other city and county offices, etc.) Fill in alilhal apply.

Agency Contact

Name Title Date Phone no. Problems; suggestions; G Report attached

Agency Conlacl


Agency Contacl


Agency Contact

Name Title Date Phone no. !'Toblems; suggestions; G Report attached

4. Other Interviews (optional) G Report attached.

0-8

20

OSWER No. 9355.7.03B-P

III. ON-SITE DOCUMENTS & RECORDS VERIFIED (Check all that apply)

I. O&M Documents /

G O&Mmanual G Readily available ~Ptodate G N/A G As-built drawings G Readily available Up to date G N/A G Maintenance logs G Readily available d"Up to date G N/A Remarks

2. Site-Specific Health and Safety Plan J«Readily available ~UPtodate G N/A G Contingency plan/emergency response plan t4 Readily available Up to date G N/A Remarks

3. O&M and OSHA Training Records G Readily available G Up to date G N/A Remarks

4. Permits and Service Agreements G Air discharge permit G Readily available G Up to date G N/A G Effluent discharge G Readily available G Up to date G N/A G Waste disposal, POTW G Readily available G Up to date G N/A G Other permits G Readily available G Up to date G N/A Remarks

5. Gas Generation Records /t;;( Readily available trUp to date G N/A Remarks

..

6. Settlement Monument Records G Readily available G Up to date IfN/A Remarks

7. Groundwater Monitoring Records Ueadily available ty(jp to date G N/A Remarks

8. Leachate Edraction Records G Readily available G Up to date 4vN/A Remarks

9. Discharge Compliance Records G Air G Readily available G Up to date ~A G Water (effluent) G Readily available G Up to date ~/A Remarks

10. Daily Access/Security Logs G Readily available G Uptadate ~/A Remarks

D-9

21


IV. O&M COSTS

I. ~M Organization State in-house G Contractor for State

G PRP in-house G Contractor for PRP G Federal Facility in-house G Contractor for federal Facility G Other

2. O&M Cost Records G Readily available G Up to date G Funding mechanism/agreement in place Original O&M cost estimate G Breakdown attached

Total annual cost by year for review period if available

From To G Breakdown attached Date Date Total cost



From To G BTeakdown attached Date Date Total cost


3. Unanticipated or Unusually High O&M Costs During Review Period Describe costs and reasons: #v

V. ACCESS AND INSTITUTIONAL CONTROLS G Applicable G N/A

A. Fencing

I. Fencing damaged Aft) G Location shown on site map ~ates secured G N/A Remarks

B. Other Access Restrictions

I. Signs and other security measures G Location shown on site map G N/A Remarks

D-IO

22

OSWER No. 9355 7-03B-P

C. Institutional Controls (ICs)

l. Implementation and enforcement Site conditions imply ICs not properly implemented G Yes G N/A~oSite conditions imply ICs not being fully enforced G Yes No G N/A

Type ofmonitoring (e.g.• self-reporting, drive by) Frequency Responsible party/agency Contact

Name Title Date Phone no.

Reporting is up-to-date G Yes G No G N/A Reports are verified by the lead agency G Yes G No G N/A

Specific requirements in deed or decision documents have been met G Y~s G No G N/A Violations have been reported G Yes G No G N/A Other problems or suggestions: G Report attached

2. Adequacy G ICs are adequate G les are inadequate G N/A Remarks

D. General

I. VandalisnYtrespassing G Location shown on site map G No vandalism evident Remarks

2. Land use changes on site G N/A Remarks

3. Land use changes off siteG N/A Remarks

VI. GENERAL SITE CONDITIONS

A. Roads G Applicable G N/A

l. Roads damaged G Location shown on site map G Roads adequate G N/A Remarks

D-11

23


B. Other Site Conditions

Remarks Ke' o/E:

-,

VII. LANDFILL COVERS VApplicable G N/A

A. Landfill Surface

I. Settlement (Low spots) G Location shown on site map G Settlement not evident Areal extent "./&,,1 £ Depth.-

Remarks

2. Cracks G Location shown on site map vCracking not evident Lengths Widths Depths

Remarks

3. Erosion G Location shown on site map ~rosion not evident Areal extent Depth Remarks

4. Holes G Location shown on site map esAf~les not evident Areal extent Depth Remarks

5. Vegetative Cover tJ"'Grass riover properly established G No signs of stress G Trees/Shrubs (indicate size and locations on a diagram) Remarks

6. Alternative Cover (armored rock. concrete, etc.) G N/A Remarks

7. Bulges G Location shown on site map V'Bulges not evident Areal extent Height Remarks

D-12

24

8. G Wet areas G Ponding G Seeps G Soft subgrade Remarks

9. Slope Instability Areal extent Remarks

B. Benches

channel.)

I. Flows Bypass BeRemarks

nch

2. Bench Breached Remarks

3. Bench OvertoppRemarks

C. Letdown Channels

I. Settlement Areal extent Remarks

2. Material DegradMaterial type Remarks

3. Erosion Areal extent Remarks

ed

ation


g/Wet areas/water damage not evident G Location shown on site map G Location shown on site map G Location shown on site map G Location shown on site map

G Slides G Location shown on site map

G Applicable efN/A (Horizontally constructed mounds of earth placed across a steep landfill side slope to interrupt the slope in order to slow down the velocity of surface runoff and intercept and convey the runoff to a lined

G Location shown on site map



G Applicable o/N/A (Channel lined with erosion control mats, riprap, grout bags, or gabions that descend down the steep side slope of the cover and will allow the runoff water collected by the benches to move offof the landfill cover without creating erosion gullies.)

G Location shown on site map Depth

G Location shown on site map Areal extent

G Location shown on site map Depth

Areal extent Areal extent Areal extent Areal extent

~o evidence of slope instability

6/A or okay

G N/Aorokay

Wet AreaslWater Damage

G N/A or okay

G No evidence of settlement

G No evidence ofdegradation

G No evidence of erosion

D-13

25


G Location shown on site map G No evidence of undercutting Depth

Type G No obstructions Areal extent

Type

4. Undercutting Areal extent Remarks

5. Obstructions G Location shown on site map Size Remarks

6. Excessive Vegetative Growth G No evidence of excessive growth G Vegetation in channels does not obstruct flow G Location shown on site map Remarks

D. Cover Penetrations

\. Gas Vents G Properly securedllockedG Functioning G Evidence ofJeakage at penetration G N/A Remarks

2. Gas Monitoring Probes

Areal extent

G Applicable G N/A

~Active G Passive G Routinely sampled G Good condition

G Needs Maintenance

G Properly securedilockedG Functioning .~outinelYsampled ~oOd condition G Evidence ofJeakage at penetration G Needs Maintenance G N/A Remarks

3. Monitoring Wells (within surface area OfJ~) G Properly secured/lockedG Functioning Routinely sampled ~OOd condition

G Needs Maintenance G N/A G Evidence of leakage at penetration Remarks

4. Leachate Extraction Wells G Properly securedllockedG Functioning G Evidence of leakage at penetration Remarks

5. Settlement Monuments Remarks

G Routinely sampled G Good ~ition G Needs Maintenance N/A

G Located G Routinely surveyed ~N/A

0-14

26


E. Gas Collection and Treatment G Applicable G N/A

1. ~s Treatment Facilities Flaring G Thermal destruction G Collection for reuse

G Good condition G Needs Maintenance Remarks

2. ~ Collection Wells, Manifolds and Piping Good condition G Needs Maintenance

Remarks

3. Gas Monitoring Facilities (e.g., gas monitoring ofad~ent homes or buildings) G Good condition G Needs Maintenance N/A Remarks

F. Cover Drainage Layer G Applicable u/N/A

I. Outlet Pipes Inspected G Functioning G N/A Remarks

2. Outlet Rock Inspected G Functioning G N/A Remarks

G. Detention/Sedimentation Ponds G Applicable "'N/A

1. Siltation Areal extent Depth G N/A G Siltation not evident Remarks

2. Erosion Areal extent Depth G Erosion not evident Remarks

3. Outlet Works G Functioning G N/A Remarks

4. Dam G Functioning G N/A Remarks

0-15

27

OSWER No 9355 7-038·P

H. Retaining Walls G Applicable ~N/A

1. Deformations G Location shown on site map G Deformation not evident Horizontal displace!TIent Vertical displacement Rotational displacement Remarks

2. Degradation G Location shown on site map G DegTadation not evident Remarks

I. Perimeter Ditches/Off-Site Discharge G Applicable ~N/A

I. Siltation G Location shown on site map G Siltation not evident Areal extent Depth Remarks

2. Vegetative Growth G Location shown on site map G N/A G Vegetation does not impede flow Areal extent Type Remarks

3. Erosion G Location shown on site map G Erosion not evident Areal extent Depth Remarks

4. Discharge Structure G Functioning G N/A Remarks

VIII. VERTICAL BARRIER WALLS G Applicable vN/A

J. Settlement G Location shown on site map G Settlement not evident Areal extent Depth Remarks

2. Performance MonitoriogType of monitoring G Performance not monitored Frequency G Evidence of breaching Head differential Remarks

0-16

28


IX. GROUNDWATER/SURFACE WATER REMEDIES G Applicable ~N/A ..

A. Groundwater Extraction Wells, Pumps, and Pipelines G Applicable <YN/A

1. Pumps, Wellhead Plumbing, and Electrical G Good condition G All required wells properly operating G Needs Maintenance G N/A Remarks

2. Extraction System Pipelines, Valves, Valve Boxes, and Other Appurtenances G Good condition G Needs Maintenance Remarks

3. Spare Parts and Equipment G Readily available G Good condition G Requires upgrade G Needs to be provided Remarks

B. Surface Water Collection Structures, Pumps, and Pipelines G Applicable $""N/A

J. Collection Structures, Pumps, and Electrical G Good condition G Needs Maintenance Remarks

2. Surface Water Collection System Pipelines, Valves, Valve Boxes, and Other Appurtenances G Good condition G Needs Maintenance Remarks

3. Spare Parts and Equipment G Readily available G Good condition G Requires upgrade G Needs to be provided Remarks

D-17

29


c. Treatment System G Applicable G N/A

1. Treatment Train (Check components that apply) G Metals removal G Oil/water separation G Bioremediation G Air stripping G Carbon adsorbers G Filters G Additive (e.g., chelation agent, flocculent) G Others G Good condition G Needs Maintenance G Sampling ports properly marked and functional G Sampling/maintenance log displayed and up to date G Equipment properly identified G Quantity ofgroundwater treated annually G Quantity of surface water treated annually Remarks

2. Electrical Enclosures and Panels (properly rated and functional) G N/A l;> Good condition G Needs Maintenance Remarks

3. Tanks, Vaults, Storage Vessels G N/A G Good condition G Proper secondary containment G Needs Maintenance Remarks

4. Discharge Structure and Appurtenances G N/A G Good condition G Needs Maintenance Remarks

5. Treatment Building(s) G N/A G Good condition (esp. roof and doorways) G Needs repair G Chemicals and equipment properly stored Remarks

6. Monitoring Wells (pump and treatment remedy) G Properly secured/lockedG Functioning G Routinely sampled G Good condition G All required wells located G Needs Maintenance G N/A Remarks

D. Monitoring Data

1. Monitoring Data G Is routinely submitted on time G Is of acceptable quality

2. Monitoring data suggests: G Groundwater plume is effectively contained G Contaminant concentrations are declining

D-18

30


C. Early Indicators of Potential Remedy Problems

Describe issues and observations such as unexpected changes in the cost or scope ofO&M or a high frequency of unscheduled repairs, that suggest that the protectiveness of the remedy may be compromised in the future.

"/P IV tG-

D. Opportunities for Optimization

Describe possible opportunities for optimization in monitoring tasks or the operation ofthe remedy. eON €.

0·20

31

APPENDIXD Site Photos

LAND FILL) L- ooK/Nt. NW F~oM Se-

No'"£ A c.~ I 'J E.. L> A.s S '1'''5. If M r M 0 N I TE. f<.. (Nb

WE-LL.S

34