INTRODUCTION

East Bay Municipal Utility District (EBMUD) and the Central Valley Regional Water Quality Control Board (CVRWQCB) jointly submitted to the State Water Resources Control Board (SWRCB) on May 16, 1997 a proposal for remediation of the Penn Mine site pursuant to California Water Code (CWC) Section 13397 et seq., hereinafter referenced as the Remediation Plan. EBMUD and the CVRWQCB have identified themselves jointly as the remediating agencies. The SWRCB is the oversight agency for the Remediation Plan and must determine if it satisfies the conditions of CWC 13398.3(a) through (m).

The purpose of this staff report is to determine if the Remediation Plan complies with the conditions of CWC 13398.3(a) through (m).

BACKGROUND

Penn Mine operated intermittently from the 1860s to the mid-1950s for the production of copper and zinc ore. Activities in the mined area included mining from numerous shafts and adits, and processing of copper and zinc ore. Penn Mine has since been abandoned from further production and processing of copper and zinc ore as a surface mining operation. The Penn Mine site is located in northwestern Calaveras County near the inlet to Camanche Reservoir on the Mokelumne River. In the early 1960s, EBMUD acquired a portion of the Penn Mine site to facilitate development of Camanche Reservoir. The remainder of the site is owned by New Penn Mines, Inc., a defunct Nevada Corporation.

Significant Acid Rock Drainage (ARD) problems have developed at the Penn Mine site resulting in adverse environmental impacts to several water bodies. ARD is characterized by low pH and elevated metal concentrations. ARD is generated when sulfide-bearing (pyritic) mine waste, such as that existing at Penn Mine, is exposed to water and oxygen to initially oxidize the mine waste. The products of this initial reaction are ferrous ion, sulfate, hydrogen ion, and heat. Bacteria that thrive in these products can act to increase the rate of reaction and allow pyrite to be oxidized in the absence of oxygen. These bacteria are most active in the low pH waters that are generated in this process. The ARD generation process then proceeds as long as the mine waste is in contact with water. In turn, metals are leached from waste ore that is in contact with the ARD.

The Penn Mine site contains an area of approximately 22 acres of mine waste piles, mill tailings, mixed soil and fill, and affected soil and fill that have been contaminated by ARD. Diversion facilities bypass storm water runoff from approximately 442 acres of upstream watershed around the contaminated area. However, most of the diversion facilities are unlined and some lack the grade necessary for an efficient carrying capacity.

Some diversion facilities are locally in contact with ARD generating waste. Mine Run Diversion, which at times exhibits some characteristics of ARD, is used to divert stream runoff from North Fork and South Fork Mine Run Creeks to Oregon Gulch in order to prevent that runoff from coming into further contact with waste rock material and the Penn Mine impoundments.

Currently, ARD is collected behind Mine Run Dam (MRD) that forms Mine Run Dam Reservoir (MRDR) at the confluence of Mine Run Creek and Hinkley Run Creek. MRD was completed in 1979. MRDR has a capacity of approximately 38 acre-feet. Several other impoundments that collect ARD within the contaminated area exist upstream of MRDR on both creeks. The combined capacity of those impoundments is approximately 24 acre-feet. To reduce the volume of ARD collected at MRDR, ARD is diverted from MRDR to the two most upstream impoundments on Mine Run Creek to utilize their available surface area for evaporation. In spite of the various efforts to reduce the volume of ARD collected upstream of MRD, MRDR and most of the other impoundments often carry a significant amount of ARD during the wet season, and their full capacities often are not available to collect all of the ARD that is generated after storms.

In 1993, an In-Line System treatment plant (ILS) was installed to treat ARD collected at MRDR for discharge to Camanche Reservoir and the Mokelumne River. Under this treatment method, the pH of the influent ARD is raised by the addition of a lime slurry to neutralize its acidity and precipitate metal hydroxides from the ARD in a clarifier arrangement.

In March 1993, the U.S. Environmental Protection Agency (U.S. EPA) issued a Finding of Violation and Order for Compliance (309 Order) to EBMUD, pursuant to Sections 308 and 309 of the Clean Water Act (CWA). The 309 Order includes requirements for diversion of storm water, criteria for operation and maintenance of the ILS, requirements for long-term pollution control, and monitoring and reporting requirements. The U.S. EPA modified the 309 Order several times since 1993 to reflect conditions most current to the project.

In December 1993, the Ninth Circuit Court of Appeals upheld a decision of the U.S. District Court for the Eastern District of California, holding that defendants, EBMUD and the CVRWQCB, were required under the CWA to obtain a National Pollutant Discharge Elimination System (NPDES) permit for the discharge of ARD from MRDR into Camanche Reservoir and the Mokelumne River. The Committee to Save the Mokelumne River (CSM) was the plaintiff in that court action. Certiorari was subsequently denied by the U.S. Supreme Court. In March 1994, EBMUD and the CVRWQCB submitted a Report of Waste Discharge and applied for authorization to discharge waste under an NPDES permit. Supplemental information was submitted to support the application in May and July 1994. A draft NPDES permit was circulated by the SWRCB in February 1995.

In August 1995, the U.S. District Court issued an order approving a stay to the NPDES permitting process. Additionally, a separate action before the Sacramento Superior Court was stayed. Both actions were stayed in accordance with the terms of an Agreement to Stay Proceedings stipulated among the above-referenced parties.

That agreement allowed EBMUD, the CVRWQCB and the SWRCB, in conjunction with the U.S. EPA and CSM, to develop a long-term plan for the Penn Mine site and to negotiate its implementation and a final settlement agreement. This was conditioned on the completion of a Draft Environmental Impact Report (Draft EIR) pursuant to the California Environmental Quality Act (CEQA) within a year of execution of that agreement. Pending completion of the Draft EIR, additional time was allowed for negotiation of a final settlement agreement. The intent of the parties since has been to achieve a consensus-based solution that provides for the long-term protection of the water quality at the site.

EBMUD and the CVRWQCB served as lead agencies under CEQA for the Penn Mine Site Long-Term Solution Project. Volume I of the Draft EIR was circulated for public review in May 1996. Volume I describes and evaluates seven primary alternatives for a long-term solution project at the Penn Mine site. Volume II of the Draft EIR, circulated for public review in September 1996, provides a description and rationale for the selection of the preferred alternative, known hereinafter as Alternative 5A. A Comment Response Document (CRD), circulated for public review in February 1997, contains copies of all comments received by the lead agencies, responses to all comments, and text revisions to the Draft EIR that have been made as a result of the comments received. EBMUD certified the Final EIR, comprised of the above referenced CEQA documents, and approved the project at its meeting on February 25, 1997. The CVRWQCB certified the Final EIR and approved the project at its Board Meeting on February 28, 1997.

A letter dated February 18, 1997 from Alexis Strauss, Acting Director for the Water Division of U.S. EPA, Region 9, expressed support for the measures undertaken to develop a comprehensive long-term pollution control project for the abandoned Penn Mine and belief that the project will have substantial water quality and other environmental benefits. U.S. EPA's letter further expressed that Alternative 5A is the preferred project which, if fully implemented, should achieve a complete and final remediation and should comply with all applicable laws.

The Settlement Agreement for the project was signed by representatives for EBMUD, the CVRWQCB, the SWRCB, and CSM on February 25, 1997.

SATISFACTION OF REMEDIATION PLAN REQUIREMENTS

The following analysis cites the submittal requirements required by CWC 13398.3 and provides a brief description of how the Remediation Plan supports the requirements: [CWC 13398.3(a) Identification of the remediating agency, and a certification that the remediating agency is a remediating agency as defined in this chapter.]. EBMUD and the CVRWQCB have identified themselves as the remediating agencies and have certified that they are public agencies which have prepared and submitted a remediation plan to the SWRCB in accordance with CWC Section 13397.5.

[CWC 13398.3(b) Identification of the abandoned mined lands that are the subject of the plan.]

The abandoned mined lands that are the subject of the Remediation Plan correspond to those that are associated with implementation of Alternative 5A, which is described in Volume II of the EIR and the CRD. The Penn Mine site qualifies as abandoned mined land because: (1) it is an area where surface mining operations have been conducted; (2) mining operations have ceased for a period over one year; (3) there is no interim management plan in effect at the site; (4) there are no financial assurances that are adequate to perform reclamation at the site; and (5) the mined lands at the site are adversely affected by past mineral mining.

[CWC 13398.3(c) Identification of the waters of the state, if any, that are affected by the abandoned mined lands.]

The Remediation Plan identifies Hinkley Run Creek, Mine Run Creek, Oregon Gulch, and Camanche Reservoir as waters of the State that are affected by the abandoned mined lands.

[CWC 13398.3(d) A description of the physical conditions at the abandoned mined lands that are causing or have caused adverse water quality impacts.]

Volume I of the Draft EIR, which is incorporated by reference in the Remediation Plan, contains an extensive, detailed description of physical conditions at the site. ARD has been and is generated on site where mine waste materials are exposed to oxygen and surface and ground water. The ARD is collected on-site by several surface impoundments. However, the capacity of the ponds has been exceeded during high or sustained precipitation events, and pond solutions have been discharged from the mine site to Camanche Reservoir and the Mokelumne River.

[CWC 13398.3(e) A description of the practices, including system design and construction plans, and operation and maintenance plans, proposed to reduce, control, mitigate, or eliminate the adverse water quality impacts and a schedule for implementing those practices. If the plan is prepared for an existing remediation project, the remediation plan shall include a description of practices that have been implemented and the practices that are proposed to improve the existing project, if any.]

The preferred alternative, Alternative 5A, is described in detail within the EIR in Sections 2.1 and 2.2 of Volume II, and the CRD. Alternative 5A provides water quality protection at the Penn Mine site through the excavation and removal of all waste materials, estimated to be from 300,000 to 332,000 cubic yards, and disposal in a landfill constructed on site. The CRD indicates that hydraulic flushing or an equivalent means of removing fine or residual waste materials will be incorporated in the project as mitigation; the extent of which will be determined following inspection of mechanical excavation. The landfill will comply with the requirements of Title 23, California Code of Regulations, Chapter 15, Article 7. MRD and all impoundments in the area affected by ARD shall be removed to allow water runoff from Hinkley Run Creek and Mine Run Creek to flow into Camanche Reservoir and the Mokelumne River. The ILS shall be operated and maintained during construction as necessary; its use will be terminated following removal of MRD. A soil cover will be placed over areas disturbed by remediation. The site shall be restored in a manner that approximated pre-mining conditions with respect to vegetation and habitat. A plug shall be installed at Shaft No. 4. Mine Run and Hinkley Run diversions shall be removed, and natural surface water flow through the restored stream channels shall be reinstituted. Alternative 5A is estimated to require three construction seasons, as detailed in Section 2.2 of Volume II of the EIR.

[CWC 13398.3(f) An analysis demonstrating that the implementation of the practices described in the plan have caused, or are expected to cause, a substantial improvement in water quality for the identified waters.]

The Remediation Plan provides a demonstration that implementation of Alternative 5A is expected to cause a substantial improvement in water quality for the identified waters. Section 4.5 in Volume I of the EIR used a geochemical model and representative site surface and ground water concentrations of copper and zinc to estimate loads that could have discharged to Camanche Reservoir and the Mokelumne River, except for the presence of MRD and the ILS treatment system. Using data from 1992 through 1995, the model estimated that the copper loads that could have been discharged to Camanche Reservoir would have ranged from about 16,000 pounds in 1992 to more than 24,000 pounds in 1993. The zinc loads that could have been discharged ranged from 30,000 pounds in 1992 to more than 45,000 pounds in 1993. The ILS currently achieves a 98 percent or greater treatment efficiency which reduces the surface water component of estimated metal loads in the model.

Section 7.10.1.5 in Volume I of the EIR likewise predicts that implementation of Alternative 5A will achieve or exceed a 98 percent metal load reduction from the site due to waste removal and stream bed restoration. This is predicted to occur after soluble metal contributions from residual acidic salts, which are present in shallow bedrock and alluvium, are reduced through flushing. Factors that will affect the actual degree of water quality improvement include: (1) the completeness of waste removal; (2) the extent and quantity of residual acidic salt; deposits; (3) the quantity of water runoff in the reclaimed area; and (4) the degree and timing of revegetation success. The Remediation Plan has been developed in consideration of these factors.

An additional improvement in water quality through implementation of Alternative 5A is expected from the removal of pyritic waste materials and their isolation from contact with water. There will be a significant reduction in the generation of the products from the ARD process, which include hydrogen ion and sulfate. Accordingly, the restored site should not be capable of generating the low pH waters that currently characterize the site. Lower total dissolved solids, suspended solids, and turbidity are also expected. The additional run-on from the watershed surrounding the site, provided by the removal of diversions, should provide dilution to residual metals and the other constituents that remain after implementation of the Remediation Plan. Diversions to Oregon Gulch will no longer be necessary.

The Remediation Plan should restore the site including Hinkley Run and Mine Run Creeks to conditions approximating a pre-mining environment due to the improvement of water quality and revegetation. Accordingly, significant environmental benefit should be achieved with respect to beneficial uses that may be reestablished at the site, including recreation, water supply, riparian vegetation, aquatic habitat, and animal habitat. Restoration of beneficial uses at the site will be strong evidence of improved water quality.

[CWC 13398.3(g) A description of monitoring or other assessment activities to be undertaken to evaluate the success of the implemented practices during and after implementation, including an assessment of baseline conditions.]

The Remediation Plan describes that the monitoring program will be designed to be in compliance with the requirements of the U.S. EPA 309 Order. It will build upon the baseline monitoring that has been performed to date, including parameters currently being sampled, as well as others related to verification of performance of site restoration. This monitoring program will exceed the monitoring requirements of CWC 13398.3 which only must confirm the Remediation Plan's success at improving water quality.

[CWC 13398.3(h) A budget and identified funding to pay for the implementation of the plan.]

The Remediation Plan has identified a budget of $10,000,000 for the project, whereby EBMUD and the CVRWQCB have each agreed to fund up to $5,000,000 of the total project costs. Detailed cost estimates will be developed as final designs are prepared.

[CWC 13398.3(i) Remediation goals and objectives.]

The objectives of the Remediation Plan are: (1) to develop a long-term solution that provides for water quality protection of the Mokelumne River and Camanche Reservoir; (2) to develop a solution that is consistent with applicable laws and regulations; (3) to develop a solution that provides ecological and habitat restoration to the extent reasonably achievable; and (4) to develop a solution that is economically feasible to install, operate, and maintain. These objectives support the primary goal to provide long-term water quality protection from ARD at the Penn Mine site.

[CWC 13398.3(j) Contingency plans.]

The Remediation Plan refers to Section 5.2 of Volume II of the EIR for mitigation measures which may be implemented, depending on the effectiveness of the project. There is no contingency plan to restore the site to pre-remedial conditions because the Remediation Plan includes removal and isolation of all waste materials.

[CWC 13398.3(k) A description of the remediating agency's legal right to enter and conduct remedial activities.]

The legal right for the remediating agencies to enter property to conduct remedial activities under the Remediation Plan shall be pursuant to provisions under CWC 13304(b)(2) and (b)(3).

[CWC 13398.3(l) The signature of an authorized representative of the remediating agency].

The Remediation Plan has been signed by authorized representatives of both EBMUD and the CVRWQCB.

[CWC 13398.3(m) Identification of the pollutants to be addressed by the plan.]

The Remediation Plan has listed pollutants to be addressed by the project.

CONCLUSIONS

SWRCB staff concludes that the Remediation Plan satisfies the requirements for submittal pursuant to CWC 13393.3(a) through (m). Evidence in the record supports that implementation of the Remediation Plan will substantially improve water quality that has been affected by the Penn Mine site.