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Hyland Facilities Associates - Decision 2, April 13, 1995

Decision 2, April 13, 1995

Decision of the Commissioner

This Decision is issued in relation to the application of Hyland Facility Associates (the "Applicant") for permits to construct and operate an incinerator ash monofill for the disposal of ash from municipal solid waste incinerators. The proposed facility would be located in the Town of Angelica in Allegany County, New York.

Upon careful review of the record of this proceeding and the attached Hearing Report (the "Report") of Administrative Law Judge ("ALJ") Susan DuBois, the Report, including its Findings of Fact and Conclusions, is adopted as my Decision in this matter, subject to my findings, conclusions and comments stated below. Concurrently, the Report, together with the Final Environmental Impact Statement ("FEIS") submitted in concert with the Report and the prior Commissioner's Decision and ALJ's Report/FEIS of June 21, 1993, as incorporated by reference in these proceedings, are adopted as the FEIS for this project.

The Commissioner's prior decision of June 21, 1993, denying issuance of the requested permits, noted that the hearing record did not support a finding that the site was unacceptable. The Decision found only that the Applicant did not satisfy the requirements of 6 NYCRR Part 360 and the State Environmental Quality Review Act ("SEQRA"). Upon reconsideration of that Decision, and subsequent appeals on newly raised issues, the application was remanded for further proceedings on the following issues: (1) separation to groundwater [former 6 NYCRR 360-2.13(d)]; (2) slope stability [former 6 NYCRR 360-2.12 (c)(4)]; (3) foundation analysis [former 6 NYCRR 360-2.13 (i)]; (4) liner performance [6 NYCRR 360-2.14(b)(1)(iii)]; and (5) soil testing and soil materials. At the remanded hearing, the following additional issues were also considered: (6) financial assurance [6 NYCRR 360-2.19]; and (7) turbidity requirements of the storm water general conditions in the State Pollutant Discharge Elimination System ("SPDES").

The ALJ found that there was no dispute concerning the Applicant's foundation analysis, the Applicant had agreed to comply with the regulatory standards for financial assurance and the Applicant had demonstrated, by a preponderance of the evidence, that its proposed project would comply with regulatory standards on the issue of liner performance. While the ALJ noted that the Applicant's analysis of the necessary and available soil quantities had "infirmities", the record amply demonstrates that sufficient soil material is available on site from the expanded mine areas.

The ALJ recommended denial of the application based upon an analysis of three specific areas: (1) separation to groundwater; (2) slope stability; and (3) storm water management regarding turbidity. Each of these topics are addressed below.

Introduction

The regulatory criteria specified in Part 360 are designed to provide environmental protection, as well as certainty to applicants who undertake landfill projects. The level of technical detail required in an application depends upon site conditions, to the extent they are known or can be reasonably inferred from borings, well logs, soil sampling and testing, and other data. Professional judgments supplement this information and assess the level of detail submitted to meet the regulatory criteria, the validity of the data and the probable environmental impacts expected.

To ensure regulatory compliance and conformity, the confidence level assigned to technical evidence must consider regulatory criteria, permit conditions and the reliability of the information. While scientific or engineering "certainty" is a laudable goal, it is an unrealistic expectation in complex environmental matters. Requiring an excessive level of confidence unacceptably delays a decision when the additional information requested would not demonstratively add substance. The burden imposed upon a permit applicant is to demonstrate, by a preponderance of the evidence, that its proposal will be in compliance with all applicable laws and regulations administered by the Department. 6 NYCRR 624.9(b) and (c).

The case now before the Department is illustrative of this point. The intricate geology of the Applicant's site necessitates complicated evaluation; to appreciate in full detail the entire spectrum of geological and geotechnical aspects would require a level of scrutiny that exceeds a reasonable standard of judgment on the application. As current data provides sufficient background, prudent use of resources demands a careful sifting of only the existing evidence to make a reasonable determination.

Separation to Groundwater

The Applicant has applied for a variance to former 6 NYCRR 360-2.13(d), regarding separation to groundwater. As part of the justification for the granting of the variance, the Applicant has included a pore pressure relief system beneath the liner of the ash monofill. The purpose of the pore pressure relief system is to remove groundwater and construction water before any hydrostatic pressure is exerted on the landfill. The proposed pore pressure relief system will consist of a geocomposite material installed in the subgrade to drain water that might otherwise reach the bottom of the landfill cell liner. If the head in the pore pressure relief system remains less than its thickness, it will perform as required.

To qualify for a variance under former Subdivision 360-2.13(d), the Applicant was to employ a worst case scenario in designing and analyzing the pore pressure relief system (Fourth Interim Decision, August 29, 1994). If the Applicant could show the pore pressure relief system would perform as required under the worst case scenario and met the standards of former 6 NYCRR 360-1.7(c), a variance would then be granted.

The ALJ was concerned that the Applicant had not demonstrated that the pore pressure relief system would perform as intended, based upon the presence of perched groundwater tables and varied low soil permeabilities found on the site. The information provided, regarding these permeabilities, allegedly raised serious questions as to whether the pore pressure relief system, as designed, was adequate. These conclusions do not, however, take into account the efficiency of the pore pressure relief system or a reasonable worst case scenario.

Pore pressure relief systems provide an extra margin of safety to alleviate groundwater pressures. The efficiency of the system, coupled with a reasonable worst case estimate of the amount of water the system may be called upon to transmit, do provide an adequate basis upon which to predict the functionality of the system.

The Applicant designed the pore pressure relief system based upon a worst case scenario, assuming that virtually the entire subgrade was saturated and the subgrade permeabilities would not be lowered by subgrade preparation activities. Additionally, the Applicant described contingency activities if saturated soils are found in the subgrade near the pore pressure relief system, thereby ensuring that capacity is not exceeded.

Utilizing a conservative approach, the Applicant also assumed the hydraulic gradient was parallel to the prepared subgrade. The Intervenors instead relied upon vertical gradients from wells that would be subject to over excavation, a less conservative method. The Applicant used reasonable values for permeabilities of the subgrade at the interface with the pore pressure relief system to assess whether the pore pressure relief system would handle flows anticipated at the facility. Moreover, the permeability for the soil calculations should be based upon a geometric mean, as utilized by the Applicant, and not upon an arithmetic mean. (Matter of Monroe County - Mill Seat Solid Waste Landfill, Commissioner's Ruling on Motion to Reopen the Hearing, April 14, 1993)

As a preponderance of the evidence illustrates that the Applicant assumed a worst case scenario, it is not necessary to require additional information. The Applicant has demonstrated the substantial conservatism of its design. Accordingly, I conclude that the Applicant has demonstrated, by a preponderance of the evidence, that the pore pressure relief system will function as intended. Based upon the foregoing analysis, the request for the variance is granted.

Slope Stability

The Applicant was required to demonstrate compliance with former 6 NYCRR 360-2.12(c)(4), regarding slope stability. As part of this demonstration, the Applicant was requested to identify clearly all input parameters utilized in the slope stability analyses. An evaluation of the slope stability is directly dependent upon such parameters (Fourth Interim Decision). A record was developed addressing this issue and is set forth below.

A reasonable evaluation of the input parameters for slope stabilization must be based upon sound engineering principles, generally accepted in landfill design and which account for specific site characteristics, to the extent they are known. The evaluation of input parameters, other than those proposed by the Applicant and approved by DEC staff, must be based upon sound engineering judgment and be relevant to the Applicant's proposed project.

The Applicant's analysis is based on sound engineering judgment. Sufficient evidence has been provided to conclude that it has met its burden concerning slope stability. Although the ALJ would have preferred that the Applicant supply additional information on this issue, she concluded, and I concur, that the Intervenors did not demonstrate that slope failure would occur.

In concluding that sufficient information was supplied by the Applicant to warrant approval, the Intervenors presented evidence on slope stability: the unit weight of ash per cubic foot; the friction angle to be ascribed to ash and the subgrade material; the presence of plastic tarps discarded in the ash; cover material; and the use of the undrained and unconsolidated case for analysis. However, a careful evaluation of the Intervenors' evidence on slope stability reveals a lack of reliability and trustworthiness. Information that contains analytical errors, methods of questionable reliability or the use of outdated computer software that does not adequately take into account all the constituents of the design, must be discounted when more reliable information is presented. The Applicant has provided this "more reliable" information.

The level of detail demanded by the ALJ for final resolution of this issue extends beyond what is required. As noted above, a standard of reasonableness is warranted when determining the level of detail for evidence to be deemed "sufficient". Inadequate or incomplete information should be considered in light of existing "valid" information. A proper balance imposed on this record must weigh the sound and legitimate methods and tests performed by the Applicant and the nature of the evidence offered to contradict them.

The predictions or estimates made by the Applicant and DEC staff are within the realm of reasonable certainty and reliability when evaluated in the foregoing context. Accordingly, the Applicant has supplied sufficient information to demonstrate that the slope stability analyses meet the regulatory standards.

Storm Water Management (Turbidity)

Information was required to determine whether the turbidity requirements of the storm water general SPDES permit would be met. As part of that showing, the Applicant was required to submit a description of the storm water management controls. In the event site conditions precluded gathering the information, reasonable assumptions would be adopted to perform the analysis. As part of that inquiry, sizing of the storm water retention basins would be evaluated.

Evaluation of the storm water turbidity issue was required as it is relevant to Part 360 and SEQRA compliance. An applicant must provide reasonable assurances and demonstrate that the devices it proposes will adequately control turbidity.

The ALJ concluded the Applicant had not met the burden of proof concerning turbidity, in regard to some portions of the Project life. It was claimed that the application lacked an estimate of the total suspended solids or other parameters which could be expected for the outfalls; this data was necessary to ascertain whether the turbidity requirements of the storm water general SPDES permits would be met.

The Applicant did, however, submit a description of storm water controls which included engineering techniques relating to soil stabilization, runoff control and sediment control. An integrated approach was established with specific measures to be taken to control turbidity. Detention pond sizing was to be accomplished through standard DEC guidelines governing such devices to control turbidity. The record reveals that even the Intervenors' expert agreed that the Applicant's submittals provided adequate assurances to control turbidity. Department staff also approved the Applicant's submission. Consequently, I am satisfied with the level of review performed on this issue in the remand hearing and conclude that the total storm water management control system, as proposed and addressed by staff, will meet the intent of the Fourth Interim Decision.

I must emphasize, however, that the Applicant must submit final design plans to the DEC for review and approval prior to the General Permit becoming effective. A special condition to this effect must be added to the permit to construct.

In summary, I find no evidence in the hearing record to conclude that the application should be denied and hereby approve the application. Staff are directed to amend the permits with the above referenced special permit condition and issue the permits for the project.

Based upon my review, I find that the requirements of Environmental Conservation Law ("ECL") 8-0109 and 6 NYCRR 617 have been met. Consistent with the social, economic and environmental considerations, the action being approved is that one, from among the reasonable alternatives, which minimizes or avoids adverse environmental effects to the maximum extent practicable. I am confident that the adverse environmental effects revealed in the environmental impact statement process will be minimized or avoided to the maximum extent practicable. Pursuant to 6 NYCRR 617.9(a), I direct that this Decision be effective 10 days after this date and that, as soon as possible thereafter, Staff shall issue the necessary permits for this Project consistent with this Decision.

IN WITNESS WHEREOF, the Department of Environmental Conservation has caused this Decision to be signed and issued and has filed the same with all maps, plans, reports, and other papers relating thereto in its office in the County of Albany, New York this 13th day of April, 1995.

TABLE OF CONTENTS

Summary Statement

Proceedings

Remanded and New Issues

Findings of Fact, Discussions and Conclusions

Summaries of issues that were not remanded

Recommendations

Appendices

Comments on DEIS *

Responses to Comments on the DEIS *

1993 Hearing Report and Final EIS *

November 18, 1993 Ruling on Motion for Reconsideration *

March 7, 1994 Addendum to Application *

May 11, 1994 Ruling on Motion for Reconsideration *

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* The Final Environmental Impact Statement ("FEIS") for this project, as supplemented during the remanded hearing, consists of the following: the DEIS and application (Exhibits 5 through 23 of the hearing record); the comments on the DEIS; the Applicant's responses to the comments on the DEIS (Exhibits 129 and 129B of the hearing record); the 1993 Hearing Report and FEIS which was issued on June 21, 1993 with the original Decision; the November 18, 1993 Ruling on Motion for Reconsideration which superseded the original Decision; the March 7, 1994 Addendum to the Application; the May 11, 1994 Ruling on Motion for Reconsideration; and the present Hearing Report/FEIS.

Due to their volume, the DEIS and other documents identified above are not included as attachments with the present supplemental Hearing Report/FEIS, but are on file in the Department's Office of Hearings in Albany as of the date of the Department's Decision on the remanded hearing, along with the complete hearing file. The entire hearing file is available for inspection during normal business hours (Monday through Friday, 8:30 A.M. through 4:45 P.M.) at the New York State Department of Environmental Conservation, Office of Hearings, Room 409, 50 wolf Road, Albany, New York 12233-1550, Attention: Susan J. DuBois, Administrative Law Judge, telephone 518-457-3468.

Copies of portions of the hearing file are also available for inspection during normal business hours at the Region 9 Office of the Department at the following address: 270 Michigan Avenue, Buffalo, New York 14203-2999, Attention: Regulatory Affairs Unit, telephone 716-851-7165.

Summary Statement

The following is a summary of the Hearing Report and Final Environmental Impact Statement ("FEIS") for the remanded review of the Hyland Facility Associates application for a solid waste management facility permit. The present report is based on the record of the hearing which took place initially in 1992 and 1993 plus the record of additional hearing dates in 1994 which took place after the application was remanded for further hearing on certain issues. The present report supplements the earlier Hearing Report/FEIS which was issued with the Department of Environmental Conservation's June 21, 1993 Decision on the application.

Hyland Facility Associates (the "Applicant"), P.O. Box 68, Belmont, New York 14813, applied to the New York State Department of Environmental Conservation (the "Department") for permits for a proposed landfill to be located on Herdman Road in the Town of Angelica, Allegany County. The Applicant proposes to construct and to operate a monofill for the disposal of incinerator ash from municipal solid waste incinerators. The Applicant would also mine clay on the site for use in construction of the monofill.

The project would require permits to construct and to operate a solid waste management facility, pursuant to Environmental Conservation Law ("ECL") Article 27 Title 7 and Part 360 of the Official Compilation of Codes, Rules and Regulations of the State of New York ("6 NYCRR Part 360"). When the hearing began, the project also required a mined land reclamation permit pursuant to ECL Article 23 Title 27 and 6 NYCRR Parts 420 through 423, but the mining activities would now be regulated under the Part 360 permit. The project would require water quality certification pursuant to 6 NYCRR Section 608.7. Storm water runoff from the site would be subject to the Department's August 1, 1993 General Permits (GP-93-05 and GP-93-06) under the State Pollutant Discharge Elimination System ("SPDES", ECL Article 17 Title 8).

The proposed ash monofill would consist of two contiguous cells on an approximately 28 acre area, located on a 289 acre parcel of land. Approximately 62 acres of the site would be used as support facilities including buildings, roads, leachate containment structures, borrow areas and sediment ponds.

The Applicant proposes to accept only ash from municipal waste incinerators. The waste accepted at the facility would include treated fly ash, bottom ash and combined ash, and the maximum disposal rate would be 500 tons per day. The expected life of the monofill is 19 years.

The Department, as lead agency for the review of the project under the State Environmental Quality Review Act ("SEQR"), required preparation of a Draft Environmental Impact Statement. The Department accepted the DEIS on March 19, 1991.

On June 21, 1993, following the initial portion of the hearing, the Commissioner of Environmental Conservation accepted a Final EIS on the project and made findings that the project as proposed did not satisfy the requirements of SEQR. The Applicant subsequently moved for reconsideration of the June 21, 1993 Decision. The acceptance of the FEIS and the SEQR findings were rescinded by the Commissioner on November 18, 1993 in his ruling on the motion for reconsideration.

The November 18, 1993 ruling remanded the application for further hearing, which would take place after the Applicant submitted certain additional information. The ruling identified five issues which would be addressed in the hearing and gave the parties the opportunity to raise additional issues limited to compliance with new operational requirements in Part 360 (which had been amended), changes in the proposal and changes in the draft permit other than those directed by the ruling.

In March 1994, the Applicant submitted a application addendum. Additional correspondence regarding identification of issues for the remanded hearing, clarification of the November ruling, and other matters took place in the spring and summer of 1994.

The hearing resumed on October 11, 1994 before an Administrative Law Judge from the Department's Office of Hearings, pursuant to 6 NYCRR Part 624. The hearing continued for an additional nineteen days, concluding on November 23, 1994.

The following issues were considered in the remanded adjudicatory hearing: (1) the requested variance from the requirement for five foot separation between seasonal high groundwater and the landfill's liner system; (2) stability of the landfill slopes; (3) the foundation analysis conducted for the landfill; (4) water accumulation in the liner system; (5) soil testing and materials; (6) financial security for closure and post-closure care; and (7) compliance with the turbidity requirements of the SPDES general permits for storm water.

The first five of these issues were issues that had been adjudicated in the initial portion of the hearing and were remanded. The last two were new issues.

In the March 1994 application addendum, the Applicant requested a variance from the requirement for five foot separation between seasonal high groundwater and the liner system. The Applicant modified the project to include a pore pressure relief system which would consist of a layer of geocomposite drainage material located in the subgrade six inches below the bottom of the liner system and which would drain water into the groundwater suppression system trenches.

Evaluating whether the pore pressure relief system would function as intended involves a number of factors including the permeability of the subgrade soil. The 1993 Report/FEIS had described inadequacies associated with the in situ permeability data which was in the record of the 1992-93 hearing. In the remanded hearing, the Applicant relied on a limited subset of these data, adding to the unreliability of its assumption about the average permeability of the subgrade. The value for average permeability did not take into account the data from soils which could be expected to remain in the subgrade after the landfill is built and which could be expected to have higher permeabilities than the ones used in the average.

Because of this and other problems, the Applicant has not demonstrated that the pore pressure relief system would function as intended and the record indicates that in at least some portions of the landfill the groundwater flowing into the pore pressure relief system could exceed the capacity of the system to carry it away. Under certain other conditions, the groundwater could be prevented form entering the pore pressure relief system and pressure could build up a short distance below it. If the pore pressure relief system does not function properly there could be adverse effects on the stability of the liner and of the landfill in general. Although the Applicant demonstrated that the alternative of placing additional fill to raise the level of the subgrade would be very costly, it did not demonstrate that the proposal would meet the portion of the variance standard concerning adverse impacts and consistency with the performance expected from application of Part 360.

In remanding the slope stability issue, the November 18, 1993 ruling stated that the Applicant would need to perform analyses which reflect the current design of the monofill and the soil types anticipated to be underneath the facility down to the bedrock interface. The hearing record, from both 1992-93 and the remanded hearing, indicates that there are several different soil types which would exist in the subgrade after the landfill is built and that the range of properties of these soils would need to be taken into account in analyzing the stability of the landfill.

The Applicant's slope stability analyses in the remanded hearing again treated all of the subgrade soils as one material and used a non-conservative input for it. The record still does not contain relevant tests that represent the soil types that would be in the subgrade. The Intervenors demonstrated the need for analysis of two additional types of slope failure but these have not been done in a manner which would produce results that could be compared with the appropriate factors of safety. Some of the problems with the analyses in the remanded hearing were also identified in the initial portion of the hearing. The Applicant has not demonstrated compliance with the Part 360 requirement concerning landfill stability.

Part 360 also requires that a foundation analysis be performed to determine the structural integrity of the subgrade to support the weight of the landfill and to support the overlying facility components. The facility components include the leachate collection system pipes. In the remanded hearing, the Applicant presented results of additional analyses which demonstrated compliance with this requirement. This issue was the subject of relatively little testimony in the remanded hearing. The preponderance of the evidence indicates that the weight of the landfill will not cause the leachate collection system pipes nor the liner immediately under them to settle to an unacceptable extent.

The November 18, 1993 ruling stated that the Applicant had been unable to demonstrate that the site contained sufficient materials to meet all cover, berm and liner system requirements. The ruling required that the Applicant provide an analysis of expanding the mined area or of the traffic impacts of importing off-site materials. In the remanded hearing, the Applicant chose to evaluate expanding the mine, rather than importing materials. Although the expanded mine would provide larger amounts of materials, the Applicant's analysis of the available and required materials was similar to that in the initial portion of the hearing and had some of the same infirmities. The soil quantities were also based to a large extent on the assumption that all of the materials would be available at the same time, which would not occur. The impacts of either of two possible mine expansions would not be significantly greater than those of the mine as initially proposed. Impacts of truck traffic for importing additional off-site materials were not reviewed.

With regard to the issue of the water balance and leachate in the liner system, the Applicant presented additional modeling of leachate generation and leachate head. The Applicant also modified the application with regard to the permeability of the drainage layer materials of the liner system. The additional modeling demonstrated compliance with the relevant requirement of Part 360, which requires that the leachate head on the liner not exceed one foot at the expected flow capacity except during storm events.

The General Permits for discharge of storm water from construction or from industrial sites came into effect on August 1, 1993. The issue in the remanded hearing was whether the project would meet the turbidity requirements of the General Permits. Turbidity is the amount of light that is scattered or absorbed by a water sample, and it serves as an indirect measure of the amount of suspended material in the water. Both General Permits require that the regulated activity produce no increase in turbidity that will cause a substantial visible contrast to natural conditions.

The project as described in the application and the application addendum would not comply with the provisions regarding turbidity during at least some portions of the project life. The Applicant relied to a significant degree on statements that it would modify the project in ways to be determined at some future time, in order to comply with the turbidity-related requirements of the General Permits. The ways in which the project would need to be modified in order to comply have not been identified sufficiently to demonstrate that the project, as it stood at the close of the record in January 1995, would comply with the turbidity requirements of the General Permits.

The issue of financial security for closure and post-closure care involved two questions: use of a mechanism other than a trust fund for these costs, and whether the methods proposed for accruing funds were sufficient to assure that the funds would be available when needed. After this issue was identified, the Applicant proposed to use a trust fund in place of the forms of financial assurance which it had proposed in its March 1994 documents. Following further discussion and modifications at the hearing, the issue was resolved and no testimony on this issue was necessary.

The Hearing Report and FEIS which was prepared following the remanded portion of the hearing recommends that the requested permit be denied. The record of the remanded hearing does not demonstrate that the project would comply with relevant requirements of Part 360, the SPDES General Permits or the State Environmental Quality Review Act.

Proceedings

Hyland Facility Associates (the "Applicant"), P.O. Box 68, Belmont, New York 14813, applied to the New York State Department of Environmental Conservation (the "Department") for permits in connection with a proposed landfill to be located on Herdman Road in the Town of Angelica, Allegany County. The Applicant proposes to construct and to operate a monofill for the disposal of incinerator ash from municipal solid waste incinerators. The Applicant would also mine clay on the site for use in construction of the monofill.

The application was initially determined to be complete in early 1991. The Department's initial hearing on the project occurred on dates in 1991, 1992 and 1993. A Decision was issued on June 21, 1993 which denied the application. The Applicant subsequently moved for reconsideration of the Decision. On November 18, 1993, the Commissioner of Environmental Conservation issued a Ruling which superseded the Decision and remanded the proceeding for further hearings on a set of issues identified in the ruling.

The present Hearing Report and Final Environmental Impact Statement was prepared after the remand portion of the hearing and is a supplement to the original Hearing Report and Final Environmental Impact Statement (the "1993 Report/FEIS"). The present Hearing Report/FEIS makes reference to sections of the 1993 Report/FEIS that need not be restated here, and includes both additional findings and changes in certain findings.

Permits

The permits for which the Applicant initially applied are permits to construct and to operate a landfill, pursuant to Environmental Conservation Law ("ECL") Article 27, Title 7 and pursuant to Part 360 of Title 6 of the Official Compilation of Codes, Rules and Regulations of the State of New York ("6 NYCRR Part 360"), and a mined land reclamation permit pursuant to ECL Article 23, Title 27 and 6 NYCRR Parts 420 through 423. Procedures governing hearings on applications for these permits are contained in ECL Article 70 and in 6 NYCRR Part 624. The application is designated as DEC Application No. 9-0232-3/1-0.

In September, 1991, after the initial two hearing sessions, the Applicant also applied for a Water Quality Certification pursuant to 6 NYCRR Section 608.7, in conjunction with its application to the U.S. Army Corps of Engineers for a permit to fill approximately 1.9 acres of wetland on the site which are under federal jurisdiction.

As of the time of the remanded hearing, an additional requirement was in effect regarding regulation of storm water discharges under the State Pollutant Discharge Elimination System ("SPDES", ECL Article 17, Title 8). The Department Staff determined that the Project was subject to the General Permits for storm water discharges (GP-93-05 and GP-93-06).

Pursuant to ECL Article 8 (State Environmental Quality Review Act, "SEQR") and 6 NYCRR Part 617, the Department, as lead agency, required the Applicant to prepare a Draft Environmental Impact Statement ("DEIS"). The Department accepted the DEIS on March 19, 1991.

Proceedings in 1991 - Early 1993

The events regarding the hearing notices, the initial hearing session and issues conference, subsequent correspondence, and the 1992-93 adjudicatory hearing are summarized on pages 1 through 5 of the 1993 Report/FEIS and need not be restated in the present Report/FEIS.

The 1993 Report/FEIS also contains a summary of the positions taken by the parties in the 1991-1993 hearing, a discussion of certain relevant portions of Part 360, and a summary of several appeals which were addressed to the Commissioner and which were pending at the time of the 1993 Report/FEIS (see pages 5 through 9 of the 1993 Report/FEIS).

The Remanded Hearing

The initial Decision in this matter was issued on June 21, 1993 by former Commissioner Thomas C. Jorling. The Decision stated that the application suffered from a number of defects. The Decision concluded as follows:

On August 20, 1993, the Applicant transmitted to the Commissioner a Motion for Reconsideration. The Motion requested a determination that permits should be issued to the Applicant. The Motion also requested, if the permits were not issued, that the matter be remanded for further consideration of only those issues which the Commissioner determines are outstanding and that the matter be remanded to an Administrative Law Judge ("ALJ") other than the one who held the initial hearing.

After providing an opportunity for the other parties to respond to the Motion, on November 18, 1993 Commissioner Jorling issued a Ruling on Motion for Reconsideration (the "November Ruling"). This Ruling superseded the June 21, 1993 Decision and was made retroactive to the time of the Decision. The acceptance of the Final Environmental Impact Statement and the SEQRA determination on the Decision were rescinded. The Ruling remanded five issues for additional hearing, before the same ALJ who had held the initial hearing (Susan J. DuBois). The Ruling also concluded that several other issues which were adjudicated in the initial hearing had been resolved or could be resolved. The Ruling required the Applicant to submit certain supplemental information, and provided for an opportunity for new issues to be raised concerning new operational requirements of 6 NYCRR Part 360 or project changes.

The five issues which were remanded were as follows: (1) the requirement for five foot separation between seasonal high groundwater and the liner system; (2) slope stability; (3) foundation analysis; (4) water accumulation on the liner system; and (5) soil testing and soil materials.

On December 29, 1993, the Applicant submitted supplemental application materials in response to the November Ruling. The Applicant further revised and supplemented these materials in response to questions by the Department Staff. On March 31, 1994 the Department Staff stated that its review of the materials was complete and that the application was approvable and ready for further adjudication.

A notice of completion of the Final EIS had been published in the Department's Environmental Notice Bulletin on June 30, 1993. A notice of revision of the Final EIS was published in the February 9, 1994 Environmental Notice Bulletin. A notice of the application addendum and the reconvened adjudicatory hearing was published on April 13, 1994 in the Environmental Notice Bulletin and on April 14, 1994 in both the Wellsville Daily Reporter and the Olean Times Herald.

On March 2, 1994, the Town of Angelica (the "Town") and Concerned Citizens of Allegany County ("CCAC") submitted a Motion for clarification and reconsideration of the November Ruling and related matters. The Motion argued that the October 9, 1993 version of Part 360 should govern the application, requested clarification of the status of the hearing report, requested reconsideration of the November Ruling as it related to the environmental monitoring plan for the landfill, and stated that two corollary issues should be included in the remanded hearing.

On May 11, 1994, Acting Commissioner Langdon Marsh issued a Ruling on the Motion (the "May Ruling") which, among other things, provided that the application would be subject to the standards contained in the prior version of Part 360 plus the operational requirements of the new Part 360. The May Ruling also stated that the findings of fact in the hearing report remain valid although the November Ruling did reach different conclusions based on the facts in the hearing report. The May Ruling stated that additional information or changes made to the project might require revision of the findings or might make some of them irrelevant. The May Ruling further discussed the environmental monitoring plan and stated that the two proposed issues were already subsumed in the issues that were remanded.

Following an opportunity for comment on the supplemental application materials, I issued Rulings dated June 24, 1994 regarding the proposed new issues and certain matters related to the five remanded issues. The June 24, 1994 Rulings added the new issue of the financial assurance for closure and post-closure care of the landfill and stated that portions of several proposed issues were actually parts of issues that had been remanded. The June 24, 1994 Rulings also stated that the proposed issues of the construction of the monitoring wells and airborne ash fugitivity were precluded by the two Rulings on the Motions for Reconsideration and would not be adjudicated in the reconvened hearing. The ruling declined to require that the Applicant apply for an individual State Pollutant Discharge Elimination System ("SPDES") permit for storm water discharges, and referred to the Commissioner a question regarding the SPDES general permits and the hearing procedures.

Various parties appealed portions of the June 24, 1994 Rulings. On August 29, 1994, Commissioner Marsh issued a Fourth Interim Decision on the appeals which modified some of the issues. It also required the Applicant to submit a description of the storm water management controls that addresses the matters covered by an appendix to the SPDES general permit for construction activities. The parties would then be provided an opportunity to raise issues regarding whether the turbidity requirements of the general permits would be met. The Fourth Interim Decision also stated that the Applicant would not need to submit revised hydrogeologic documents as part of the hearing process, as had been required by the June 24, 1994 Rulings, but that a permit condition should be added requiring the Applicant to submit revised depictions to the Department for approval prior to initiation of operation.

On September 2, 1994, the Applicant proposed to stipulate to a permit condition regarding the financial assurances issue. The Applicant offered to stipulate to the adjudicability of the storm water issue rather than consume additional time in the process of identifying issues.

The hearing reconvened on October 11, 1994 before ALJ Susan J. DuBois, at the Allegany County Museum in Belmont, New York, and continued on the following dates at either the Museum or the Allegany County Office Building, also in Belmont: October 12 through 14, October 18 through 20, October 25 through 28, November 1 through 4, November 14, 16, and 21 through 23, 1994.

The parties to the hearing were the same as those in the initial portion of the adjudicatory hearing in 1992-93 (see 1993 Report/FEIS page 3). The Intervenors had consolidated or coordinated their participation for the hearing sessions in 1994.

The Applicant called the following witnesses: Michael F. Leydecker, P.E., Chief Engineer, TGVA Engineering, Surveying, P.C.; Michael J. Mann, P.E., of McMahon & Mann Consulting Engineers; and Donald R. McMahon, P.E., of McMahon & Mann Consulting Engineers.

The Department Staff called the following witnesses: Kevin R. Hintz, P.E., Environmental Engineer II; Paul E. Eismann, Deputy Regional Permit Administrator; Gerard A. Palumbo, P.E., Environmental Engineer III; and Theodore A. Myers, P.E., Environmental Engineer II; all from the Department's Region 9 Office in Buffalo. The Department Staff also called as a witness Robert J. Phaneuf, P.E., Supervisor of the Eastern Permitting Section in the Department's Bureau of Municipal Waste Permitting, Albany.

The Town and CCAC called the following witnesses: Jeffrey C. Evans, Ph.D., Professor of Civil Engineering, Bucknell University; and Christopher M. Kenney, P.E., of Van Der Horst Geotechnical Engineering, P.C..

The Allegany County Soil and Water Conservation District (the "District") called as its witness John Wulforst, Soil Scientist.

The hearing record closed on January 9, 1995, the date of receipt of the reply briefs.

Issues

The issues which were adjudicated in the initial portion of the hearing in 1992-93 were as follows: (a) hydrogeology of the Cuba formation, a bedrock formation found under part of the site; (b) compliance with 6 NYCRR Paragraph 360-2.12(d) which specifies that in siting landfills, bedrock subject to rapid or unpredictable groundwater flow without thick, low permeability cover must be avoided; (c) location of monitoring well screens; (d) stability of the landfill slopes; (e) the foundation analysis conducted for the landfill; (f) soil tests and the acceptability of on-site soil materials for use in various components of the landfill; (g) pipe penetration of the liner system; (h) ash fugitivity; (i) blasting; (j) noise; (k) plant species conservation; and (l) compliance with the requirement for five feet of vertical separation between the base of the constructed liner system and the seasonal high groundwater table (6 NYCRR Subdivision 360-2.13(d)).

All but the last of these issues were described in more detail in the June 23, 1992 Issues Ruling and some were modified by the August 20, 1992 Interim Decision. The last issue was added by a ruling dated December 3, 1992.

The issues in the remanded hearing are as identified in the November 18, 1993 Ruling, the May 11, 1994 Ruling, the June 24, 1994 Rulings and the August 29, 1994 Fourth Interim Decision. These issues may be summarized as follows: (1) the requested variance from the requirement for five foot separation between seasonal high groundwater and the liner system; (2) slope stability; (3) foundation analysis; (4) water accumulation on the liner system; (5) soil testing and soil materials; (6) financial security for closure and post-closure care; and (7) compliance with the turbidity requirements of the SPDES general permits for storm water.

Final Environmental Impact Statement

The Final Environmental Impact Statement ("FEIS") for this project, as supplemented during the remanded hearing, consists of the following: the DEIS and application (Exhibits 5 through 23 of the hearing record); the comments on the DEIS; the Applicant's responses to the comments on the DEIS (Exhibits 129 and 129B of the hearing record); the 1993 Hearing Report and FEIS which was issued on June 21, 1993 with the original Decision; the November 18, 1993 Ruling on Motion for Reconsideration which superseded the original Decision; the March 7, 1994 Addendum to the Application; the May 11, 1994 Ruling on Motion for Reconsideration; and the present Hearing Report/FEIS.

Findings of Fact

The 1993 Report/FEIS contained findings of fact, discussions and conclusions regarding the issues which were adjudicated in the original hearing. The Commissioner's June 21, 1993 Decision accepted the FEIS as defined in the 1993 Report/FEIS, and made reference to the 1993 Report/FEIS, but did not adopt it as part of the Decision.

The November 18, 1993 Ruling on Motion for Reconsideration superseded the June 21, 1993 Decision. On March 2, 1994, CCAC and the Town requested clarification of the status of the findings of fact and conclusions of the 1993 Report/FEIS. The Commissioner's May 11, 1994 Ruling on Motion for Reconsideration stated that:

In the present supplemental Report/FEIS, some of the findings, discussion and conclusions of the original hearing report are incorporated by reference but not restated. These would include findings which relate only or primarily to issues that were not remanded. It would also include material which is not being changed but which is not necessary to restate in the supplemental Report/FEIS. Some findings, discussion or conclusions are noted as having been amended. In some of these, deleted text is indicated by dashed lines through the letters and new text is indicated by underlining. (Please note in the web version of this Report/FEIS, deleted text is in brackets and new text is in italics.)

The conclusions related to each subject area are stated immediately following the findings and discussion regarding that subject area.

Description of the Project

1. Hyland Facility Associates (the "Applicant"), P.O. Box 68, Belmont, New York 14813, submitted applications for permits in connection with the proposed construction and operation of a landfill for the disposal of ash from municipal solid waste incinerators (the "Project"). The Project would be an ash monofill for the disposal of bottom ash, combined ash and fly ash treated consistent with former 6 NYCRR Paragraph 360-3.5(g)(2) [sic, see also former 360-3.5(g)(3)]. The monofill would consist of two cells, each of which would have four subcells which would be filled in sequence, and would operate for 19 years, receiving up to 500 tons of ash per day. The Project would also include an on-site mine for excavation of soil materials to be used as liner materials, as cover and for other construction uses on site.

2. The Site of the proposed Project is located in the Town of Angelica, Allegany County, New York. The Site is on Herdman Road, south of the Village of Angelica. The Site is on a surface water drainage divide, with part of the Site draining towards the north and part towards the south. The proposed landfill cells would be on the portion of the site which slopes to the south (see maps, Appendix A and B of [this hearing report] the 1993 Report/FEIS). At the present time, the Site is primarily pasture and hayfields, with some forested areas.

3. The area of the Site is 289 acres, of which 28.27 acres would be occupied by the monofill cells and 17 acres by the soil mine. The facility would be a commercial facility and the municipal solid waste incinerators from which the facility would accept ash are not identified in the hearing record. The facility would operate on Monday through Friday, 52 weeks per year, from 7:00 A.M. to 9:00 P.M.

4. The monofill would have a double composite liner system consisting of drainage material, 60 mil synthetic liner material and low-permeability soil, with a leachate collection pipe system in each of the two liners (see Appendices C and D of [this hearing report] the 1993 Report/FEIS, and Appendix H of the present report). The leachate would be pumped into leachate holding tanks and transported away for treatment. Ditches would be used to divert surface water runoff away from the disposal and operation areas. In addition, there would be a groundwater suppression system consisting of five underground drainage lines, oriented in a north-south direction and buried in trenches filled with coarse stone drainage material. Two of the groundwater drainage lines would be located underneath the outer slopes of the east and west berms, respectively, and the other three would be located under the cell area (see Appendices C and E of the 1993 Report/FEIS). In the March 1994 Addendum to the application, the Applicant proposed to add a pore pressure relief system consisting of a geocomposite layer which would be under the entire liner, six inches below the subgrade surface, and which would drain into the groundwater suppression system trenches (see Appendix H of this hearing report). Parts of the groundwater suppression system and most of the surface water ditches south of the drainage divide would drain to a pair of sedimentation ponds located south of the cell areas. The ponds would discharge to a stream which flows off site through a ravine. The central groundwater suppression pipe would drain directly into the ravine. During construction, some of the water would be diverted to the north in order to prevent it from running onto the construction area.

5. [The subgrade, or the soil layer immediately under the liner, would be prepared as one construction process for all of cell 1, along with construction of the berms associated with cell 1.] The subgrade, or the soil layer immediately under the liner, would be prepared in as many as eight stages, corresponding to the four subcells in each of the two cells. The perimeter and interior berms for each subcell would be prepared when they became necessary, but the Applicant no longer intends to construct the berms associated with Cell 1 as one construction process. Although it is not clearly stated in the application documents or in the description of storm water controls, the Applicant stated on the record that its intention is to reserve the flexibility to prepare the subgrade of more than one subcell at a time and to do the rough preparation (i.e., excavation but not proof-rolling or installation of the pore pressure relief system) of more than one subcell at a time (transcript, p. 8262-8264). [The entire groundwater suppression system] The five groundwater collection pipes and trenches would be installed in the initial construction. Cell 1 is the northern part of the landfill and cell 2 is the southern part. The four subcells or areas within cell 1 are designated as A through D, with Area A being the west-central subcell and Area D the east subcell. As described in the operation and maintenance manual, the double composite liner system for cell 1 would be installed in phases as ash disposal progresses. The liner for Area A would be built immediately, the liner for Area B in the following construction season, and the liners for Areas C and D would be built in later construction seasons. Intermediate cover would be placed on the slopes which would receive additional ash in later phases. As filling of each Area was completed, final cover would be placed on the slopes that would not receive additional ash as the adjacent subcells were filled. Intermediate cover would be placed on landfill surfaces where filling operations would be inactive for thirty days or more. Cell 2 would follow a similar sequence, [with the subgrade being prepared all at once] with the subgrade preparation and berm construction taking place in as many as four phases, and the liner installation and filling occurring in four phases. The initial portion of the Cell 2 subgrade would be built while ash disposal is occurring in Area D of Cell 1. (The subcell operating sequence is shown in Appendix J of the present report).

Variance from Groundwater Separation Requirement

This section supplements the section in the 1993 Report/FEIS which was entitled "Hydrogeology of the Site". That section of the 1993 Report/FEIS pertains primarily, but not exclusively, to the issues of the hydrogeology of the Cuba formation, of the vertical separation between the liner system and the seasonal high groundwater table, and of compliance with 6 NYCRR Paragraph 360-2.12(d)(2) (of Part 360 as it read prior to October 1993) which states that bedrock subject to rapid or unpredictable groundwater flow without thick low-permeability cover must be avoided.

The only one of those issues which was remanded was the issue of separation between the liner and groundwater (former 6 NYCRR 360-2.13(d)). This section reads as follows:

A minimum separation of five feet must be maintained between the base of the constructed liner system and the seasonal high ground water table. At landfill sites where it has been adequately demonstrated that the underlying soils are homogeneous and have representative coefficients of permeability of less than 5 x 10-6 centimeters per second and exhibit a minimum thickness of 10 feet, this minimum five feet separation requirement may be reduced or waived. In such cases, the department will require additional groundwater drainage systems to ensure that the seasonal high ground water table does not come in contact with the lowermost portion of the landfill liner during construction and until the hydrostatic pressures are equalized by the weight of the liner system and waste.

During the initial portion of the hearing, the Applicant requested a waiver of this requirement, but withdrew the request for a waiver prior to the close of the record (see 1993 Report/FEIS, p. 5) In the 1993 Report/FEIS, the proposed project was being evaluated with respect to the requirement for five feet of separation, not with respect to the conditions for reducing or waiving the requirement. In the remanded hearing, the Applicant applied for a variance from the requirements of former Subdivision 360-2.13(d), under the variance provision of Part 360 (360-1.7(c)).

The introduction the "Hydrogeology" section of the 1993 Report/FEIS is incorporated but not repeated in the present report, as a summary of the record on these issues as it stood on March 29, 1993 when the record initially closed.

The findings concerning the remanded issue may be summarized as follows: the Applicant modified the project to include a pore pressure relief system in the subgrade, six inches below the bottom of the liner system. Evaluating whether the pore pressure relief system would function as intended involves a number of factors including the permeability of the subgrade soil. The 1993 Report/FEIS described inadequacies associated with the in situ permeability data in the record of the 1992-93 hearing. In the remanded hearing the Applicant relied on a limited subset of these data, adding to the unreliability of its assumption about the average permeability of the subgrade. Because of this and other problems, the Applicant has not demonstrated that the pore pressure relief system will function as intended and the record indicates that at least in some portions of the landfill the groundwater flowing into the pore pressure relief system could exceed the capacity of the system to carry it away.

The 1993 Report/FEIS made findings regarding the soils and water movement in them, which are restated here with changes that reflect the record developed in the remanded hearing.

6. The site is located on Peacock Hill, at elevations above sea level between approximately 1825 feet (in the ravine draining the southern part of the site) and 2000 feet (on the hill northwest of the cell area). The site is within the Allegheny Plateau physiographic province. The site is underlain by sedimentary bedrock with glacial sediments over the bedrock. The bedrock formations underlying the site are, in descending order, the Wellsville formation, the Cuba formation and the Machias formation.

7. The northern edge of the cell area is just south of a col or saddle between the 2000 foot hill and the higher top of Peacock Hill which is southeast of the cell area. The cell area is in a shallow valley through which a stream runs. The stream is shown on the U.S. Geological Survey quadrangle map as an intermittent stream but a witness for the Applicant, who had been on the site on numerous occasions including during summers, had never seen the stream go dry. The testimony in the remanded hearing includes observations of the stream being dry, but at least one of these occasions was a day on which the witness whose testimony was originally cited in this finding was also on the site. The record as a whole is inconclusive on the question of whether and under what conditions the stream dries out. South of the cell area and immediately south of the proposed sedimentation ponds, the stream flows down a relatively steep ravine. It ultimately flows into Angelica Creek a short distance above the creek's confluence with the Genesee River.

8. The stream is fed by rain runoff and by springs on the site. The main group of springs is located approximately 200 to 300 feet east of and uphill from the cell area, at test pits A-A', B-B', C-C' and J-J' (see map, Appendix G of [this hearing report] the 1993 Report/FEIS). There are at least four springs, each of which flows at a rate of about one gallon per minute. Water from these springs formerly flowed over the surface to the stream and also through the ground and into a perched water zone in the center of the shallow valley. In 1989 or 1990, during the course of the Applicant's site investigation work, a ditch was dug between the springs and the cell area, diverting the water to the south and around the cell area.

9. Although the ditch diverted the surface water, the stream has not dried out. It is not known to what extent the ditch cut off the flow of water through the soil to the perched groundwater zone but it is possible that the spring water is still recharging the perched water by moving through desiccation cracks in the altered till. As of 1994, some of the monitoring wells in the central part of the valley still had water levels near, and in some instances above, the ground surface. The stream receives water which is discharged from the perched water zone back to the surface. The amount of this discharge varies with the seasons. Groundwater flow at the bedrock-overburden interface and in the bedrock are discussed in Findings 18 to 25 below.

10. The glacial sediments on the site vary in their origin, composition and depth. The glacial sediments are relatively thin (5 to 10 feet deep) west of the proposed cell 1 and east of both proposed cells. The sediments are thicker at the center of the cell area, particularly under the west-central part of cell 2, and are up to 129 feet deep at a monitoring well several hundred feet south of the cell area.

11. The sediments can be described in terms of both their origin and their degree of weathering. The terms which witnesses for the Applicant and the Department Staff used in describing the origin of the sediments changed over the course of the 1992-93 portion of the hearing. The change in terms caused ambiguity in the testimony regarding the hydrogeology and other issues. The glacial sediments were described in the application documents primarily in terms of lodgement till and glaciofluvial sediments, without reference to ablation till. During cross-examination of the Applicant's soils and hydrogeology witnesses, these witnesses revised their description of the soils to include ablation till. As used by these witnesses, the ablation till would include some materials which the application described as glaciofluvial and some which it described as till (presumably lodgement till).

11a. The above finding relates to the record as of March 29, 1993. In the remanded hearing, the Applicant's witnesses avoided use of any "geomorphological" terms other than till and classified the soils primarily by use of the Uniform Soil Classification System (USCS). The logs for the monitoring wells which the Applicant installed in 1993 did not include descriptions of the soil in terms of its geologic origin, although these descriptions had appeared in the "Water table and remarks" column of the logs used by the Applicant in the initial hearing, and although the soils had been described in terms such as "unaltered till" and "glaciofluvial sediments" in crucial portions of the application documents. With a few exceptions, the test pit and monitoring well logs in the application documents from the initial hearing did not include the USCS classifications, although these classifications were included in some supplemental test pit logs which the Applicant used in the initial part of the hearing. In the remanded hearing, the District presented a depiction of the soil types found in some of the monitoring wells which divided the soils into more categories than were used in the initial hearing. The District's categories were based on the geologic origin and texture of the soils, and were assigned based on an interpretation of the well logs.

12. Some key terms were used with the following meanings. Lodgement till (also known as basal till) is material which was deposited under an advancing glacier and which consists of clay, silt, sand, and larger rock particles. Glaciofluvial sediments are those which were deposited by meltwater streams flowing from wasting glacial ice, both within the glacier and away from the glacier. Ablation till consists of soil and rock materials which had been carried within the glacial ice and which were deposited as the glacier melted. Glaciolacustrine sediments¹ are defined as glacial sediments carried by water and deposited in a lake or still water. Ablation till and lodgement till can be similar in appearance but can be distinguished based on their location relative to glaciofluvial sediments. Some of the near-surface sediments were described as glacial drift, which a witness for the applicant stated was a term which encompassed glacial deposits generally and which was used to describe clayey soils found in the top few feet at some parts of the site. Use of this last term was relatively consistent in the initial portion of the hearing. In the remanded hearing, the Applicant's documents and witnesses referred to the soil layer below the topsoil and extending to various depths of several feet as the "weathered soil strata" and described it as soil with a "blocky soil structure which has been disturbed by previous agricultural operations". The Applicant's project engineer testified that he would have no understanding of what "drift" means. This additional change in terminology was depicted by the Applicant as an effort to avoid confusion by avoiding the use of geomorphological terms, but the change did not have this effect.

13. A large proportion of the sediments on the site are basal till, including the relatively thick sediments underlying other sediment types. The site also has ablation till at locations nearer to the surface and at least in the center of the valley. The horizontal extent of this till is unclear in the record. The map (Exhibit 19A) which was characterized by the Applicant on January 27, 1993 as showing unaltered basal till was actually drawn, on December 10, 1992, to show the extent of unaltered till without reference to whether the till was basal or ablation till. The center of the valley also has glaciofluvial sediments and some glaciolacustrine sediments. The horizontal extent of the glaciofluvial sediments is larger than that shown on Exhibit 18A. Glaciolacustrine sediments were found a monitoring well located within the proposed cell 2 area (monitoring well ("MW")-I2) and in some wells south of the cell area.

14. At some time during the melting of the glaciers, a part of the site may have been the location of a pond or lake which was created by ice blocking the flow of melting water. The size and boundaries of the lake would have changed over the years. The site at least had areas of still water which were large enough that glaciolacustrine deposits up to six feet thick could be deposited within them. Some of the small areas of still water may have been located under the ice.

15. The center of the valley contains a mixture of glaciofluvial sediments, glaciolacustrine sediments, and till. The glaciofluvial and glaciolacustrine sediments occur as lenses whose size and degree of connection to each other are not known but their size is not negligible and there is at least some connection among them. These sediments are interlayered with the till (for example, at monitoring wells H, D2, [and] J, 6, 15, and 20). Glaciofluvial and glaciolacustrine sediments can be found below layers of unaltered till on the site (for example, at MW-D2). In the central part of the valley, having reached unaltered till is not a reliable indication that the only material further down is unaltered till extending to bedrock. The maximum depth at which the glaciofluvial and glaciolacustrine sediments occur in the central part of the valley is not known, both under the cell area and south of it. Two well logs which were included in the Addendum indicate that these sediments occur at considerable depth in the central part of the valley, within the landfill footprint and at the south berm. Alluvial outwash and silty lake sediments occurred in MW-15 at various depths between 70 feet and the bedrock at 116 feet deep. A layer of clayey lake sediment occurred in MW-20 at a depth between 41 to 46 feet below the surface.²

16. The till on the site is also described in terms of its degree of weathering, which can be identified by the soil color and in some places by the presence of desiccation cracks. The terms altered till and unaltered till could be applied to either lodgement till or ablation till. The glacial drift and the upper portion of the till contain desiccation cracks, which are silt-lined cracks formed by drying of the soil and by freezing of water in the soil. These cracks form a network of connected cracks, which was described as the reverse of a honeycomb. The cracks are both wider and more frequent near the surface and they taper until they disappear at deeper depths in the soil. The desiccation cracks are an avenue of water movement through the soil and can be saturated even if the soil matrix which they surround are unsaturated. Till containing desiccation cracks has a higher permeability than similar till without desiccation cracks. Weathered till also has a mottled color. The mottling can extend to greater depths than the depths at which one can readily detect desiccation cracks, particularly in core samples, and mottling is the main indicator of weathered till. The Applicant's witnesses used the terms "desiccated till" and "altered till" as having the same meaning.

17. A perched water table exists in the glaciofluvial and glaciolacustrine sediments in the center of the valley. In addition, some of the soil in which the perched groundwater existed as of the August 1990 water level data was altered till. The perched groundwater is depicted on a drawing of a west-east cross section of the site at a line of wells which would be at the berm between Cell 1 and Cell 2 (Exhibit 68, west-east profile B, also shown in Appendix F of [this Report] the 1993 Report/FEIS). The cross-section is based on water level readings taken during August, 1990. The perched water table would be at higher elevations in wetter times of the year and the water table as depicted on the profile is lower than the seasonal high groundwater table. A seasonally fluctuating water table also exists at Monitoring Well ("MW") I2, which is west of the western limit of the perched water as depicted on west-east profile B. The application documents do not contain a depiction of the seasonal high level of this perched water table. The revised groundwater contour map [(Exhibit 38, sheet 11)] (Exhibit 207, App. 1.5 as revised on 3/7/94) does not show the perched water table but instead shows the groundwater level near and within the bedrock, based on [December 1989] November 1993 data. The lateral extent of the perched water has not been defined but it is larger than the area labeled as glaciofluvial on exhibit 18A.

17a. The record of the remanded hearing also does not contain a depiction of the seasonal high groundwater table, as that term was defined in the applicable version of Part 360 (see definitions quoted at pages 8 and 9 of the 1993 Report/FEIS). The record does contain a sketch map of the contours of the piezometric surface in the overburden as measured in May 1994. This map shows a general pattern of groundwater flow towards the valley center. Depicting the groundwater table as that is defined in former 6 NYCRR 360-1.2(b) would require additional interpretation, to identify where the top of the saturated zone is.

17b. The evidence in the remanded hearing is consistent with the presence of a perched groundwater table in the overburden. With the exception of MW-C and possibly MW-3, the May 1994 water levels indicate the presence of a continuous water system draining towards the center of the valley and south. In most of the wells in and near the cell area, the water levels indicated either that the screen was in saturated soil or, for the wells screened in desiccated till, that the water would be continuous through the cracks although the pores of the soil itself might or might not be saturated. The fact that the water levels in the overburden wells do not all rise and fall at the same time may be due to a lag effect related to differences in permeability. The data indicate connections among various water-bearing soils in the overburden, although the connections may be complex.

Findings 18 through 25 of the 1993 Report/FEIS pertain primarily to the hydrogeology of the bedrock and the bedrock/overburden interface. These findings are incorporated but not restated in the present report (with the exception that the word "artisan" in these findings should be corrected to read "artesian").

26. The landfill subgrade would be excavated to elevations below the August 1990 elevation of the perched water table in part of cell 2 (see, for example, Appendix F of [this report] the 1993 Report/FEIS, a portion of west-east profile B). It is likelier than not that this would also be the case in part of cell 1 and the Applicant has not demonstrated that this would not occur. A portion of the perched water zone is located below the subgrade elevation. West-east profile B has not yet been revised to reflect the data from the monitoring wells which were installed in 1993. Pursuant to the August 29, 1994 Fourth Interim Decision, the Applicant will be required to submit a revised version of this profile and certain other depictions for approval by the Department prior to initiation of operation.

Findings 27 through 30 of the 1993 Report/FEIS dealt primarily with the preparation of the subgrade (as proposed in former Section 02210 of the Quality Assurance/Quality Control Manual) and with an exploratory program for replacing saturated or "unsuitable" soils in the subgrade (as stated in Special Condition 46 of the January 26, 1993 version of the draft permit). These findings have become moot, since the Applicant revised Section 02210 of the QA/QC Manual (see Addendum, section III, found in Exhibit 206) and since the draft permit no longer includes the condition requiring the exploratory program. Except as noted below, Findings 27 through 30 are omitted from the present report. If, however, the provisions discussed in these findings were again included in the proposed project, the findings would again become relevant.

The following new findings are added (27a through 27g):

27a. The Applicant now proposes to construct the subgrade and the pore pressure relief system as described in Addendum sections 1.3 and 3.4 and in the revised Section 02210 of the Quality Assurance/Quality Control (QA/QC) Manual. In some portions of the landfill footprint, referred to as cut areas, the proposed subgrade surface is below the existing grade. In other areas, referred to as fill areas, the proposed subgrade surface is above the existing grade. The depths of the cut would be 20 feet or more at places.

27b. In preparing the subgrade, the topsoil would be removed and stockpiled for later uses (cover, landscaping, etc.). In both cut areas and fill areas, the soil would be excavated to a depth of at least 2.5 feet below the existing grade in order to remove the soil strata that have been disturbed by agricultural operations and weathering (the "weathered soil strata"). If this material extends deeper than 2.5 feet below the surface, the excavation would be made deeper in order to remove it. The removed material would be stockpiled for other uses, including as subgrade fill or liner, after being reworked and/or mixed with other soils. The term "weathered soil strata," as used by the Applicant in the remanded hearing in the context of the subgrade preparation, does not necessarily mean the material which was described as "desiccated till" or "altered till" in the original application documents and the initial portion of the hearing, and the Applicant is not proposing to remove all of the desiccated till.

27c. The soil surface would be brought to a level six inches lower than the proposed final subgrade surface, by additional excavation or by placement of fill as necessary. (This surface six inches below the subgrade surface is the location at which a geocomposite material would be installed, as part of the pore pressure relief system.) In fill areas, the undercut surface on which the fill would be placed would be tested by proof rolling. Additional excavation would be performed in areas where the surface would not support the proof roller, and this process would be repeated until the surface exhibits suitable support for the proof roller. The surface would then be compacted and tested for density. Layers of fill (Type A embankment material) would then be placed, compacted and tested for density. In cut areas, the undercut surface would also be proof rolled, additionally excavated if necessary to support the proof roller, compacted and tested for density. Some shallow cut areas would require fill to replace a portion of the 2.5 foot over-excavation.

27d. Once the operations in the preceding Finding are finished, the geocomposite layer would be installed. The geocomposite is approximately 0.2 inches thick and consists of a plastic (HDPE) geonet between two layers of geotextile filter fabric. The installation process for the geocomposite is described in Section 1.3 of the Addendum to the application. An additional six inch layer of Type A embankment material would be placed on top of the geocomposite and would be compacted in a manner intended not to damage the geocomposite. The resulting surface would be the top of the prepared subgrade.

27e. Finding No. 29 of the 1993 Report/FEIS stated, in part, that, "As proposed in the Quality Assurance/ Quality Control Manual, the process of over-excavating and replacing subgrade would occur based on the results of subgrade compaction, and is not tied to the origin of the material nor to its permeability. QA/QC Manual page 02211-4 only requires that the backfill material have a permeability less than or equal to that of the remaining subgrade, but the remaining subgrade could be any material that can be satisfactorily compacted, regardless of its permeability." Section 02211 (clay liner) of the QA/QC Manual was not amended. The revised section 02210 (excavation and embankment) provides for proof rolling, which would test the ability of the upper several feet of the subgrade to support weight, and provides for testing of the compacted subgrade's density. The application documents do not, however, specify the permissible permeabilities of the subgrade and do not include permeability among the testing which would be done on the subgrade.

27f. The testimony by witnesses for the Applicant described an additional subgrade preparation process which is mentioned only in passing in the supplemental application documents. This process would involve excavating wet material or "blebs" of glaciofluvial material and replacing them with Type A embankment material. If the material was too extensive to excavate and was being recharged with groundwater, a drain similar to the groundwater suppression system drains would be installed to drain the water into the groundwater suppression system. The Application Addendum, however, does not include wet material or non-till soils in its definitions of unsuitable material, which also mention saturation only in the context of the near-surface weathered soil strata (see Addendum, p. 3.7 and revised QA/QC Manual page 02210-2). The Addendum mentions the additional drains only by stating that, "Alteration of naturally occurring unsuitable subgrade soils will be accomplished by draining excess pore pressure or excavation and recompaction" (p. 3.7). The additional drains are not specifically mentioned in the section of the QA/QC Manual which deals with subgrade preparation, except to the extent that they could be read into general references to corrective measures (pp. 02210-10 and -11).

27g. These additional drains would be a further change in the project. In the initial portion of the hearing, witnesses for the Applicant testified that in constructing a landfill, drains could be extended to areas having artesian conditions but that in such situations there would probably be a separate outlet for this drain rather than connecting it into the rest of the system. One of the witnesses stated his belief that such conditions did not exist at the site.

Findings 31 and 32 are revised as noted by the underlined text:

31. Although the application documents describe the groundwater suppression system, they do not contain any projection of the depth to which the perched groundwater table would be lowered by the five groundwater suppression system pipes and trenches and the drainage ditches other than conclusory statements in the engineering report. Although a witness mentioned having done such a calculation, the calculation apparently no longer exists and no such analysis nor its result was put into the record. The speed with which the groundwater suppression system pipes and trenches would lower the perched groundwater table is also unknown but it would be relatively slow.

32. The relationship between the depth of the drainage ditches and groundwater suppression system and the depth of the strata through which water moves into the perched groundwater zone is not well understood, and there are places, particularly north and east of the cells, at which groundwater may still be able to enter the cell area even after construction of the landfill. In the initial part of the hearing, the Applicant's witnesses had not analyzed the degree to which the soil compaction processes would cut off water movement through the desiccation cracks in the soil but relied on this as preventing recharge of the perched groundwater. This concept relies on the idea that the cracks are simply voids on the order of one-thirty second of an inch across, but this idea is contradicted by the description of the cracks as being silt-lined and the resistance which the silt offers to collapsing the cracks, even apart from other evidence indicating that the cracks may be wider. The soil compaction process would be expected to affect the permeability of only the top one or two feet of the soil. There is evidence of a groundwater table at the bedrock-overburden interface near the western part of the cell's northern boundary and at elevations below the bottom of the proposed drainage ditch near the eastern end of this boundary. Along part of the northern boundary, the desiccation cracks extend to the bedrock and farther east along this boundary there may be is a water table in the overburden. These observations suggest that groundwater would still be able to move into the cell area even after construction, and the Applicant has not demonstrated that this would not occur.

The following additional Findings pertain to the current request for a variance (32a through 32n).

32a. The functioning of the pore pressure relief system can be evaluated by comparing the predicted inflow to the system with the allowable flow capacity of the system. The inflow would consist of "subgrade inflow" (water flowing to the geocomposite from saturated areas of the subgrade) plus consolidation flow (pore water squeezed from the lower liner and subgrade as the soil consolidates under the weight of the overlying liners and ash). The subgrade inflow from saturated areas may be calculated based on the soil permeability and the gradient of the groundwater. In unsaturated areas, no water would flow into the pore pressure relief system. The allowable flow capacity is obtained by calculating the flow capacity of the geocomposite based on factors including the transmissivity and the slope of the material, and then applying reduction factors to account for field conditions which impact the long-term performance of the geocomposite.

32b. The predicted consolidation flows are significantly less than the predicted flow capacity of the geocomposite, and the Applicant's calculation of consolidation flow was not contested.

32c. The Applicant estimated the subgrade inflow by means of what it described as a worst case analysis, but for reasons discussed below this analysis was not worst case. The Applicant also used a permeability value which was unreliable, in addition to being non-conservative. The Applicant's estimate assumed that the entire subgrade was saturated, which is a conservative assumption since there would be both saturated and unsaturated areas of the subgrade. It also assumed, however, that all of the subgrade had a permeability equal to the geometric mean of permeabilities of the altered till and that the gradient was equal to the slope of the subgrade, which are not conservative assumptions. This would underestimate the inflow, in comparison with the range of permeabilities measured at the Site and possibly the gradients at certain well locations. The permeabilities have a particularly strong influence on the result.

32d. The soil at the subgrade elevation includes altered till, unaltered till, and glaciofluvial materials. These soil types have different average permeabilities, as discussed in the Hydrogeology Report Vol. 2. The subgrade preparation process would not ensure that the subgrade would have a uniform permeability nor that it would have a permeability similar to that of the altered till. The Hydrogeology Report Vol. 2 reported the following arithmetic mean values for these soil types: Altered till, 2.29 or 2.9 x 10-6 cm/sec; Glaciofluvial sediments, 8.5 x 10-5 cm/sec; Unaltered till, 8.0 x 10-8 cm/sec.

32e. As discussed in the 1993 Report/FEIS, the values for the altered till and the glaciofluvial sediments are based on very few measurements that are clearly in the stratum being described and the classifications of some of the wells are doubtful to varying degrees. The permeability of the altered till is based on four wells (4BT, I, I2 and C1). One of these wells has its screen in material which was most reliably described as glaciolacustrine material (MW-I2) and another is in till which was described as having retained some characteristic of unaltered till (MW-4BT). The permeabilities of these wells range from 3.41 x 10-9 (MW-4BT) to 6.94 x 10-6 (MW-C1).

32f. The Applicant used the arithmetic mean of each set of permeability values in the initial hearing, but used the geometric mean in the remanded hearing. The arithmetic mean gives more weight to the more permeable values. The permeability value which the Applicant used in estimating subgrade inflow was 3.85 x 10-7 cm/sec, which the Hydrogeology Report Vol. 2 reported as the geometric mean for the altered till.

32g. Despite installing five additional monitoring wells which were screened in the overburden in or near the cell area, the Applicant did not test the permeability in these wells. This information would have been useful in evaluating the subgrade inflow to the pore pressure relief system.

32h. In evaluating the subgrade inflow, the Applicant assumed that the gradient was equal to the slope of the subgrade, and described this as a conservative approach since the slope of the subgrade would be steeper than that of the existing ground surface. The slope of the subgrade, however, would be the relevant slope once the subgrade is excavated. The gradient used in the Applicant's evaluation of the subgrade inflow is a horizontal gradient. At places in the subgrade, vertical gradients exist which are larger than the horizontal gradient associated with the subgrade slope. The significance of these vertical gradients with regard to the inflow estimates is unclear in the record.

32i. Various adverse combinations of permeabilities and gradients which are not unrealistic in view of the data for the Site indicate that, for portions of the subgrade, the inflow could be greater than the Applicant's prediction of the allowable capacity of the pore pressure relief system. If the gradient is assumed to be the same as that used by the Applicant (0.09) and the permeability is assumed to be 7.7 x 10-5 cm/sec, the allowable capacity would be exceeded. To the extent that the Applicant has information about the permeability of the glaciofluvial soils, the reported arithmetic mean is a higher permeability than this, as are the permeabilities at two of the four wells which were used in arriving at the mean (MW-H and MW-H1). The reported geometric mean is 6.1 x 10-5. The only well which was unambiguously identified as being screened in glaciofluvial material was MW-K, where the permeability was reported as 4.96 x 10-5 cm/sec.

32j. The soil types and the groundwater which were found at certain monitoring well locations cannot be dismissed as isolated conditions which will be eliminated during construction. Some of these well locations (the "D" cluster and the "H" cluster) are near the proposed location of a groundwater suppression system pipe or a manhole, where there would be excavation below the general subgrade elevation and these soils might be exposed. The possibility that the wet and/or glaciofluvial deposits at these wells might be removed during this additional excavation does not, however, eliminate the likelihood that similar deposits exist and would remain a short distance below the subgrade in the area of the site whose conditions are represented by the data from these wells. The data from individual wells can be extrapolated and interpolated in order to assess the conditions in the surrounding area.

32k. In evaluating the allowable capacity of the geocomposite, the Applicant obtained a value for the capacity of the geocomposite and then applied reduction factors for intrusion (soil forcing the geotextile into the flow pathway of the geonet) and for creep (the long-term deformation of the material). The recommended reduction factor for creep is based partially on how much pressure was applied in testing the transmissivity of the geocomposite, which in turn is used in obtaining the original capacity of the geocomposite before the reduction factors are applied. The Applicant used a lower-than-recommended reduction factor for creep on the basis that the way in which the transmissivity testing was done had already included the effect of intrusion, since the material was tested between two soil layers rather than between two metal plates which was described as being the standard test. It is not clear from the record whether these factors compensate for each other in the manner proposed by the Applicant, and the effect of creep may be underestimated. Although this was in dispute at the hearing, the outcome of the dispute would not have a bearing on the outcome of the variance issue since the comparison of inflow to capacity which was cited above involved the Applicant's own estimate of the capacity.

32l. If the subgrade preparation procedures caused the soil immediately under the geocomposite to have the permeability which the Applicant assumed, but the soil below that still had a higher permeability and was saturated, the groundwater could be prevented from entering the pore pressure relief system as intended and pressure could build up under the layer of lower-permeability soil.

32m. If the capacity of the pore pressure relief system is exceeded by the flow from the subgrade, or if pressure builds up at the base of less permeable soil adjacent to the pore pressure relief system, the pressures would have a detrimental effect on liner construction and on stability of the landfill. Such additional pressures would need to be considered in the stability analyses.

32n. The Applicant requested a variance from the five foot separation from groundwater requirement since the exploratory program which had been under review in the hearing in 1992-93 had not been accepted (see former Finding No. 30 of the 1993 Report/FEIS) and since using additional fill to raise the base of the liner system would be costly. The cost for placing the additional subgrade material was estimated as approximately three million dollars. There would also be costs associated with the loss of available air space, estimated at an additional ten to twelve million dollars. Additional soil would be irretrievably used in the process.

Discussion

The Discussion section regarding the Hydrogeology issues from the 1993 Report/FEIS is incorporated but not restated in the present report, as a discussion of how the record as it stood as of March 29, 1993 was evaluated in arriving at the Findings and Conclusions of the 1993 Report/FEIS. The following additional discussion pertains to the record including the new evidence which was presented in the remanded hearing.

One of the key factors in evaluating the proposed pore pressure relief system is the permeability of the subgrade soil. The 1993 Report/FEIS described the problems with the then-existing data on the hydraulic conductivity (permeability) data for the overburden soils and the mean permeability values for the soil types described in the application. No finding about the average or representative permeability was necessary at that time, in view of the standards which were at issue at that time. The Commissioner's November 18, 1993 Ruling remanded the issue of the five foot separation from groundwater but gave the Applicant the option of demonstrating compliance with the requirement or requesting a variance.

The Applicant then requested a variance and initially submitted the application addendum at the end of 1993. On March 2, 1994, the Town and CCAC submitted a motion for reconsideration which, among other things, requested that the hearing include the additional issue of proper characterization of the hydraulic conductivities of the soil and bedrock strata. The Commissioner's May 11, 1994 Ruling on this motion stated that this proposed issue and a second one "...are already subsumed in the issues that were remanded. Both are relevant, for instance, to the question of whether a variance can be granted to the five foot separation from groundwater requirement. The findings of fact demonstrate problems with respect to both matters which will have to be addressed in the context of the remanded proceeding." The second proposed issue, of the depiction of seasonal high groundwater, was later limited as discussed in the Fourth Interim Decision.

Neither my June 24, 1994 rulings nor the Commissioner's Fourth Interim Decision excluded the sub-issue of soil permeabilities.

In the remanded hearing, the Applicant presented no additional data on soil permeabilities but instead used only a subset of the data it had used in the 1992-93 portion of the hearing. The figure which it used for the average permeability of the subgrade was based on the permeabilities for the four wells which the Applicant classified as having their screens in altered till (see Finding 32e). This number is based on only two or three measurements in this material. It also omits consideration of any of the permeabilities of the wells which were classified as representing the glaciofluvial sediments, which wells have higher permeabilities.

Despite installing five new wells which have screens in the overburden, three of which contained water on most of the dates they were measured, the Applicant has not done permeability tests on these wells. None of the witnesses who were questioned about this provided a convincing reason for why the new wells were not tested.

The Applicant's position regarding the effects of the subgrade preparation processes is both that these would produce a more or less uniform subgrade and that these would not significantly alter the soil permeability. The permeabilities measured in the wells in the subgrade soils vary significantly from each other and could not be considered to be even approximately uniform.

The application addendum stated that saturated soils exist in the subgrade only as small, isolated, discontinuous pockets and that there is not a groundwater table with a hydraulic gradient. The testimony which the Applicant presented in support of this position had less weight than the testimony which identified the presence of a perched groundwater table. The testimony which was accepted in making the Findings on this subject is also more consistent with the application documents and with the subsequent information on the site's soils and groundwater.

In the remanded hearing, the standard in question is the variance standard found in former 6 NYCRR 360-1.7(c)(2), as applied to the requirement for five feet of vertical separation between the base of the constructed liner system and the seasonal high groundwater table (former 360-2.13(d)). At the close of the 1992-93 portion of the hearing, the standard in question was the five foot separation requirement itself. At neither time was a waiver or reduction of the five foot separation requirement in question, nor the standards for such a waiver which are found in the latter part of former 360-2.13(d).

Both the 1993 Report/FEIS and the present report conclude that the five foot separation requirement itself (as opposed to the conditions on a waiver or reduction) is not limited to the time before the hydrostatic pressures are equalized by the weight of the liner system and the waste. Although variances of the five foot separation requirement can be and have been granted, the review of the impacts of granting the variance would need to take into account the long-term functioning of the pore pressure relief system or other measures which would substitute for physical separation. If the system would function for a limited time period, this would not necessarily rule out a variance but the evaluation of the impacts would need to take this into account.

The record on the variance issue includes disputes about numerous facts related to this issue. In making the findings of fact on this issue, it has not been necessary to make findings on all of these disputed facts. The record as a whole has been taken into account in making the findings, but to discuss each contention would unnecessarily lengthen the hearing report.

Conclusions - Variance from Groundwater Separation Requirement

Conclusions 1 through 4 of the 1993 Report/FEIS pertain primarily to the issue of the hydrogeology of the Cuba formation and Conclusions 7 through 11 pertain primarily to the issue of compliance with former 360-2.12(d) (avoiding areas with bedrock subject to rapid or unpredictable groundwater flow without thick, low permeability cover). Neither of these issues were remanded for further hearing. The above Conclusions are incorporated but not restated in the present report, and their significance is as modified by the Commissioner's November 18, 1993 and May 11, 1994 Rulings on the motions for reconsideration.

Conclusions 5, 6 and the last sentence of Conclusion 11 pertain to the remanded issue of 6 NYCRR Subdivision 360-2.13(d).

5. 6 NYCRR Subdivision 360-2.13(d) requires that a minimum separation of five feet must be maintained between the base of the constructed liner system and the seasonal high groundwater table. This provision applies not only at the time of construction but indefinitely. The provision at the end of the subdivision, regarding what is allowed once the hydrostatic pressures are equalized by the weight of the liner system and the waste, pertains specifically to those cases in which the separation requirement has been reduced or waived. There has been no such reduction or waiver in the present case, and the site is not eligible for such a waiver for the present permit application, including the application as modified by the Addendum documents. No waiver or reduction was requested in the remanded hearing. Instead, the Applicant applied for a variance from the requirements of 6 NYCRR 360-2.13(d).

[6. The project as described in the application would fail to comply with the five foot vertical separation requirement. The Applicant has not demonstrated that the additional conditions in the January 26, 1993 draft permit would bring the project into compliance with the five foot vertical separation requirement.] Former Conclusion No. 6 is moot since the Applicant has applied for a variance and is no longer attempting to show that the project would comply with the five foot vertical separation requirement.

Conclusions 6a through 6c are all additional conclusions related to the remanded hearing, but are written without underlining since all of the text is new.

6a. Conclusion 11 of the 1993 Report/FEIS stated that the permeability of the altered till is poorly characterized. The Commissioner's May 11, 1994 Ruling did not change this conclusion but instead said that the findings of fact demonstrate problems with respect to the data on the hydraulic conductivity of the soils (Ruling, p.3). This conclusion also has not been changed by the evidence presented in the remanded hearing. The permeabilities of the subgrade soils need to be taken into account in evaluating whether the pore pressure relief system will function as intended. The altered till is one component of the subgrade soil. The permeabilities of other soil types which will be in the subgrade are also poorly characterized. What data there is regarding the permeability of the subgrade leads to a conclusion that the Applicant, in evaluating the pore pressure relief system, has used a weakly supported and non-conservative value for the average subgrade permeability.

6b. The Applicant has demonstrated that the alternative of placing additional fill in the subgrade to ensure the five foot separation from groundwater would impose a large economic burden. The Applicant has not, however, demonstrated that the pore pressure relief system would function as intended and the record indicates that it might not function properly in the full range of conditions which could be expected in the subgrade. If the pore pressure relief system does not function properly there could be adverse effects on the stability of the liner and of the landfill in general.

6c. The project as proposed in the application addendum does not meet the standards for granting the requested variance (former 6 NYCRR 360-1.7(c)(2)).

Monitoring Wells

This issue was not remanded. The introductory section, findings and discussion in the "Monitoring Wells" section of the 1993 Report/FEIS are incorporated but not restated in the present report. Conclusions 12 and 13 of the 1993 Report/FEIS are incorporated but not restated in the present report, and their significance is as modified by the Commissioner's November 18, 1993 and May 11, 1994 Rulings on the motions for reconsideration. The Rulings precluded further adjudication of the environmental monitoring plan.

Slope Stability

This issue has to do with the question of whether the landfill and the materials on which it would be built can support the weight of the landfill without collapsing, sliding or otherwise failing. 6 NYCRR Paragraph 360-2.12(c)(4) states that: "A landfill must not be located in unstable areas where inadequate support for the structural components of the landfill exist or where changes in the substrate below or adjacent to the landfill may result in failure of the facility... Factors to be considered when determining unstable areas include: soil conditions that may result in differential setting and subsequent failure of dikes, berms, or containment structures; geologic or man-made features or events that may result in sudden or gradual failure of dikes, berms or containment structures; the anticipated loading due to height and density of waste deposition; and the stability characteristics of the waste to be deposited."

In remanding this issue, the November Ruling stated that the Applicant would need to perform analyses which reflect the current design of the monofill and the soil types anticipated to be underneath the facility down to the bedrock interface. As stated in the following section of the report, the Applicant again treated all the soils as one material and used a non-conservative input for it. The record still does not contain relevant tests that represent the soil types that would be in the subgrade. The Intervenors demonstrated the need for analysis of two additional types of failure, but these have not been done in a manner which would produce results that could be compared with the appropriate factors of safety. Some of the problems with the analyses in the remanded hearing were also identified in the initial portion of the hearing. The Applicant has not demonstrated compliance with the cited requirement.

Findings 40 through 43 of the 1993 Report/FEIS are incorporated but not repeated in the present report. Findings 40 through 43 describe the sets of slope stability analyses which were included in the record of the initial portion of the hearing, and discuss the use of textured liner material and the choice of a value used in the seismic analyses.

New Findings 43a and 43b are added:

43a. In the remanded hearing, the Applicant presented an additional set of slope stability analyses as part of the application Addendum, and made reference to an additional slope stability run which the Town and CCAC introduced into evidence. A witness called by the Town and CCAC also presented a set of slope stability analyses. The analyses presented by all of the parties treated the subgrade soil as one unit, as had been done in the initial hearing. The subgrade could be divided into multiple layers to account for differences in the soil strength.

43b. The slope stability analyses calculate a factor of safety for various slope failures. The factor of safety, in this context, is a ratio comparing the forces which cause the slope to become unstable with the forces which resist the instability. A factor of safety equal to 1.0 indicates that, if the modeling is correct, the forces causing instability equal the forces resisting instability.

Findings 44 through 46 are revised as follows (strike-through indicates deleted text, underlining indicates new text.)

44. During the testimony regarding the fifth analysis presented by the Applicant in the initial part of the hearing, the Applicant's witnesses Mr. Kogler and Mr. McMahon stated that glaciofluvial soils would have angles of internal friction similar to or greater than those for the till since glaciofluvial materials are granular, and that consequently it was not necessary to analyze the glaciofluvial soils further with regard to slope stability. This portion of the testimony did not include discussion of glaciolacustrine soils or their strength. There are no test results in the record regarding the angles of internal friction for glaciofluvial materials nor for glaciolacustrine materials, even following the remanded hearing. In addition, none of the samples used in laboratory tests which provided values for cohesion were done on glaciofluvial or glaciolacustrine materials.

45. As discussed in this Hearing Report's section on the hydrogeology issues, glaciolacustrine and glaciofluvial soils exist on the site and are not eliminated by [the procedure described in special condition number 44 of the January 26, 1993 draft permit] the procedures described in the Addendum and the revised QA/QC Manual. The application, in the map which was designated as Exhibit 18A, identifies glaciofluvial soils as being present in a small part of Cell 1, in the central part of cell 2, and south of (downhill from) the cell area. This map does not illustrate the entire area in which glaciofluvial and glaciolacustrine soils have been observed or might be expected. The logs for several of the monitoring wells in this area describe the wells as intersecting "clayey lake sediment" (MW-D, MW-D2, MW-K). The soils which would be considered glaciofluvial or glaciolacustrine have a range of textures.

46. The well logs also report the presence of some soils that tend to liquify when disturbed (MW-H, MW-H1, MW-D2, MW-2) or that are loose when disturbed (including MW-6).³ One of the Applicant's witnesses dismissed the phenomenon of liquefaction as being impossible for the soils which his colleague had sampled from the site since liquefaction happens in saturated sand but not in clay. This witness was assuming that the soil on site was uniform, which it is not. In the remanded hearing, the log entries about soils that tend to liquify were identified as being the result of a soil classification technique used in the field to test for fine- grained soils that are largely silt as opposed to clay, and as not indicating the potential for liquefaction in a slope stability context.

The following new findings (46a through 46k) are added:

46a. For the remanded hearing, the Applicant obtained new data regarding the Atterberg limits (measurements related to soil plasticity) and grain size distribution for various soil types sampled from some of the new monitoring wells, but did no additional testing of the strength of the soils. All of the test data regarding friction angles or unconfined compressive strength were data from the initial hearing. These data are from tests of till and do not include any tests of glaciofluvial or glaciolacustrine material. A deposit of wet, stratified soil was excavated in Test Pit (TP) JJJ in August 1993, but this material was not tested. To the extent that the Unified Soil Classification System ("USCS") classification was identified for the soils used in the strength tests, these soils were CL (lean clay, also referred to in the testimony as clay of low plasticity) or clay soil obtained from a stratum classified as GC (clayey gravel), the latter in the test pit labeled as both TP-8 and TP-K-K'. Field methods exist which allow measurement of various strength parameters in soils which are difficult to sample and/or are too far below the surface to sample by means of a test pit but no such tests were done despite encountering glaciofluvial and glaciolacustrine soils in three of the new monitoring wells.

46b. The soils which would remain in the subgrade may be classified as CL (lean clay) which is the group most commonly reported in the logs, CL-ML (silty clay), ML (silt), SC (clayey sand), GC (clayey gravel) and GM (silty gravel). As stated at Finding No. 11A above, relatively few of the Applicant's test pit and monitoring well logs contain both a USCS classification and a geomorphological description of the soil strata. There is not a one-to-one correspondence between the USCS classifications and the geomorphological description of the soil, as can be seen by comparing the USCS classifications with both the District's depiction of the soil strata and the Applicant's choice of soil layers to be used in evaluating the friction angle of the glaciofluvial and glaciolacustrine soils.

46c. The Applicant assessed the friction angle of the glaciofluvial and glaciolacustrine soils by using a table from a reference book which gives approximate ranges of friction angle for various types of cohesionless soils (for example, sand and silt). This table is not, however, of use for cohesive soils, and some of the glaciofluvial and glaciolacustrine soils are cohesive soils.

46d. The stability of slopes in construction projects can be analyzed in a number of ways, depending on whether or not the soils have consolidated under the weight which was placed on them during construction and depending on whether the failure which is being modeled progresses fast enough that pore water pressures associated with the failure do not have a chance to dissipate.

46e. The unconsolidated, undrained case (also known as the "end of construction" case) needs to be evaluated in situations where all of the following exist: the soils are cohesive, the soils are nearly or fully saturated, and the rate at which loads are applied to the soil is faster than the rate of consolidation or pore pressure dissipation. Most of the soils in the subgrade are cohesive soils. Some of the soils are saturated. In the context of the slope stability analyses, saturation relates to whether the pores of the soil themselves are saturated, in addition to there being continuous water through the cracks in the soil. Although the extent of such saturated soil has not been specifically defined, significant portions of the subgrade have this condition.

46f. In the present project, ash and cover material would be placed at various locations in the landfill as it is developed. Each additional load which is applied in a particular area begins an additional process of consolidation. Lower soil permeability is related to a slower consolidation rate. Estimates of the length of time for the subgrade at this site to be ninety percent consolidated range from less than six years to over 200 years, based on different thicknesses of subgrade material and on dissipation of pressure in two directions or one direction, respectively. Under some portions of the landfill pressure dissipation would occur downward as well as upward, but if there is an aquaclude between the upper subgrade and the bedrock/overburden interface this would greatly inhibit pressure dissipation downward where this aquaclude exists. Cracks in the soil would allow more rapid dissipation. Radial dissipation of pore pressure would need to be taken into account if the area being loaded is not large in comparison with the depth of the subgrade, as may be the case since the landfill would be filled a subcell at a time, but no data were available for quantifying radial dissipation.

46g. The landfill would be developed as subcells⁴ which would be filled in time periods that are comparable to or shorter than the estimated times for the subgrade to substantially consolidate. Although it would take nine years for Cell 1 to be entirely filled, portions of Cell 1 would be filled to almost their final height in shorter times, on the order of a few years. This would be so at the cross section of the landfill which was used in the slope stability analyses in the remanded hearing. Similarly, although filling of Cell 2 would be completed nineteen years after construction began on Cell 1, the subcells of Cell 2 would be brought from empty to nearly their fill height in a few years (see Appendix J of this report for subcell operating sequence).

46h. Conditions which would create a need to analyze the unconsolidated, undrained case exist in at least a portion of the subgrade. The Applicant has not done such an analysis and has only limited data which would be useful for it. The standard penetration test values from the monitoring wells can be used to obtain a crude approximation of the strength parameter (cohesion) used in this type of analysis. The Intervenors presented a set of slope stability analyses done using this approximation. In addition to the standard penetration test data, the Applicant does have unconfined compressive strength data for soil from three test pits (TP-V-V', W-W', and X-X'). The unconfined compressive strength can be divided by two to obtain the cohesion. The Applicant does not, however, have data which reflects the range of soils that would need to be considered in this analysis since these samples are from the base of test pits where the soil at the bottom of the pit was desiccated till and was described as "hard." None of the three test pits were in glaciofluvial or glaciolacustrine soil, none were in other than CL soil, and there is no indication that they reflect the soils in which the standard penetration test values were relatively low (indicating weaker soil).

46i. The standard penetration test ("SPT") involves driving a sampling device into the soil in a specified manner and counting the number of blows required to drive the sampler through a specified distance in the soil. The resulting blow count can increase if the sampler hits gravel particles. In gravelly soil, the SPT results obtained at two nearby locations can vary widely, but the lower values are significant. The SPT blow counts can be approximately correlated to cohesion. The choice of which of several possible correlations should be used depends on the type of soil, and the way in which this should be done was in dispute between the Applicant and the Town/CCAC. Under either interpretation, however, some of the soils in which relatively low blow counts were observed are in soil types for which one would use the correlation that produces the lowest cohesion values.

46j. The areas which the Town/CCAC witness described as having "relatively low blow count" materials were ones in which the blow counts at various depths in the soil were either less than 30 or less than 25. These occur in portions of the cell area, particularly in the center of the valley, and in some places at depths which would be below the subgrade elevation. In some locations in and near the cell area, blow counts in the teens were observed. The relatively low blow counts reported in the logs do not necessarily correspond to a particular USCS soil group nor to glaciofluvial or glaciolacustrine soil, although the area in the center of the valley is the same general area of the site that was described as having glaciofluvial sediments or ablation till. These materials would need to be taken into account in some manner in a stability analysis, whether they exist as a continuous stratum or whether they are randomly located in the areas of the site where they appear in the monitoring wells.

46k. The strength estimates which are obtained using the SPT results are unreliable in comparison with other testing of the soil materials in question. In the present case, however, only one kind of soil was tested by other methods which provide a value for cohesion. The SPT correlations provide the only indication of cohesion values for the areas of the subgrade in which the SPT values were relatively low. The slope stability analyses presented by the Town and CCAC assigned one strength value to the entire subgrade, as had the Applicant's analyses. The Town/CCAC analyses used several different cohesion values which were based on the materials which have relatively low blow counts. While the subgrade could be divided into additional layers in some manner to better reflect the variability in its strength, the evidence demonstrates the importance of taking into account the variability of the soil and performing the unconsolidated, undrained analyses. The Applicant has done neither of these things in its analyses. The evidence also demonstrates that the role of the subgrade soils in potential failures is not negligible or speculative.

Findings 47 and 48 from the 1993 Report/FEIS are revised and supplemented as follows:

47. The fifth slope stability analysis which the Applicant presented in the initial portion of the hearing took into account the presence of artesian pressure at the bedrock overburden interface but only evaluated this effect with regard to one location at the landfill (along north-south station 8+25). This location was described as corresponding with the maximum height of the landfill and the maximum potentiometric head, but at this location the data used in the analysis show no artesian pressure under the landfill itself, only to the south of it. No similar analyses were run at other locations during the initial part of the hearing.

48. As of the close of the record in March 1993 none of the slope stability analyses, including the last one, considered pore water pressure due to the perched water table. As discussed in the section of this report regarding the hydrogeology issues, the Applicant has had not demonstrated that this water table will even be lowered to five feet below the bottom of the liner. The Applicant is now seeking a variance from the five foot separation requirement. The groundwater table's horizontal extent and depth below the subgrade, and changes in these over the lifetime of the landfill, are not known.

New Finding 48a is added:

48a. In the application addendum, the Applicant's analyses considered the piezometric head under the landfill by using the water level data from wells which have their screens in the bedrock or possibly at the bedrock overburden interface. None of these analyses included a piezometric head associated with perched groundwater, on the assumption that perched groundwater would be drained and would not exist at the site. An additional slope stability analysis, which the Applicant presented in its rebuttal case, included perched groundwater in an analysis which was otherwise the same as one in the application addendum. Including the perched groundwater reduced the predicted factor of safety. The evidence regarding the variance request indicates that the perched groundwater will be present at some places in the subgrade, up to a level six inches below the liner system (i.e., at the pore pressure relief system's geocomposite material) even if the pore pressure relief system works as intended, and that at some places in the subgrade the inflow into the geocomposite could exceed the geocomposite's capacity. The perched groundwater would need to be taken into account.

Finding No. 49 of the 1993 Report/FEIS related to pressure resulting from leachate buildup in the primary drainage layers of the liner. This Finding has become moot since runoff from the interim cover slopes will no longer be directed into the drainage material (see Finding 72b). Finding 49 is omitted from the present report.

Finding 50 from the 1993 Report/FEIS is revised and supplemented as follows:

50. In the initial portion of the hearing, the slope stability analyses assumed that the contents of the landfill were solely ash. The properties of cover materials which would become mixed with the ash