HomeMy WebLinkAbout06-22-20 City Commission Packet Materials - C13. TO for FY21 Groundwater and Methan Monitoring at Story Mill (Bozeman) Landfill
Commission Memorandum
REPORT TO: Honorable Mayor and City Commission
FROM: Shawn Kohtz, City Engineer SUBJECT: Task Order – Fiscal Year 2021 Groundwater and Perimeter Methane Monitoring, Assessment of System Performance and
Effectiveness Bozeman Landfill AGENDA ITEM TYPE: Consent MEETING DATE: June 22, 2020 RECOMMENDATION: Authorize the City Manager to execute the attached Task Order for fiscal year 2021 Groundwater and Perimeter Methane Monitoring, Assessment of System Performance and Effectiveness at the Story Mill Landfill. BACKGROUND: The purpose of this task order is to continue semi-annual groundwater monitoring and monthly perimeter methane monitoring through June 2021 and to evaluate performance of the remediation systems and their effect on adjacent groundwater quality. The purpose of the semi-annual groundwater monitoring and monthly perimeter methane monitoring activities is to maintain regulatory compliance. The purpose of the evaluation of the remediation
systems is to document performance and effectiveness of the Air Sparging and Soil Vapor Extraction systems. Additionally, fiscal year 2020 monitoring indicates the need to further evaluate hydrogeology and refuse distribution in the southeast corner of the landfill. This need is triggered by observed increases in volatile organic compound (VOC) concentrations near the corner of the landfill. Additional remediation system upgrades may be needed in the future as a
result of this investigation work. This task order will be implemented under the professional services agreement referenced here: http://weblink.bozeman.net/WebLink8/0/doc/63070/Electronic.aspx. UNRESOLVED ISSUES: None. FISCAL EFFECTS: The cost of this work will be $94,800.00. This work will be paid for with solid waste funds dedicated to this purpose. Approval of this task order is contingent on approval of this element of the Final Budget.
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ALTERNATIVES: As suggested by the City Commission. Attachments: Task Order – 2020-2021 - Groundwater and Perimeter Methane Monitoring, Assessment of System Performance and Effectiveness
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Tetra Tech
851 Bridger Drive, Suite 6; Bozeman, MT 59715
Tel 406.582.8780 Fax 406.582.8790 tetratech.com
TASK ORDER 2020 - 2021 GROUNDWATER AND PERIMETER METHANE MONITORING ASSESSMENT OF SYSTEM PERFORMANCE AND EFFECTIVENESS BOZEMAN LANDFILL May 26, 2020 CLIENT: CONSULTANT: The City of Bozeman Tetra Tech, Inc.
P.O. Box 1230 851 Bridger Drive, Ste 6 Bozeman, Montana 59711-1230 Bozeman, MT 59718
Attention: Mr. Shawn Kohtz, PE Attention: Mr. Kirk A. Miller INTRODUCTION
The purpose of this task order is conduct semi-annual compliance groundwater monitoring and monthly perimeter methane monitoring at the Bozeman Landfill and to conduct detailed evaluations of the performance of the remediation systems and their effect upon groundwater remediation. These activities will be conducted between July 1, 2020 and June 30, 2020 and are directed at meeting DEQ Solid Waste rules and the requirements of DEQ’s June 6, 2014 letter requiring the City of Bozeman to conduct a Corrective Measures Assessment and implement remedial measures. The purpose of the evaluation of the remediation system is to document performance and effectiveness and progress towards meeting groundwater and soil gas remediation goals. The
remediation system is comprised of the expanded landfill gas (LFG) collection system, the soil vapor extraction (SVE) system, and the air injection (AI) system.
Groundwater monitoring wells were installed, and a groundwater monitoring program was implemented beginning in 1981. Monitoring results have shown that groundwater quality has been impacted primarily by VOCs originating from the Bozeman Landfill’s unlined waste cell.
Ten additional monitoring wells were installed during 2014 and increased the total number of monitoring stations to 33. Monitoring results indicate a southwesterly to westerly groundwater flow. Tetrachloroethene has exceeded regulatory standards in groundwater, on City of Bozeman park property adjacent to the landfill property. Based upon recommendations from the Initial Remediation System Evaluation report (March 9, 2018), we recommend two additional groundwater monitoring events be conducted for the next year or two so that quarterly data is available for water quality trending analysis. Hence, September 2020 and March 2021 groundwater monitoring events are proposed to supplement the December 2020 and June 2021 monitoring events, which are conducted for compliance with DEQ’s landfill closure requirements. SCOPE OF SERVICES This task order includes the following work activities:
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Task Order – 2020 to 2021 Groundwater and Methane Monitoring and Assessment Bozeman Landfill, Bozeman, Montana May 26, 2020
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• Task 100 - Perimeter Methane Monitoring
• Task 200 - Additional Groundwater Monitoring Events
• Task 300 - December 2019 Compliance Groundwater Monitoring
• Task 400 - June 2020 Compliance Groundwater Monitoring
• Task 500-Evaluate hydrogeology and refuse distribution in southeast corner of landfill
• Task 600 - Project Management, Statistical Analysis, and Reporting The scope of work for these tasks are outlined below. Task 100 Perimeter Methane Monitoring
Task 1 includes 12 months (from July 2020 to June 2021) of methane monitoring activities. Monitoring is conducted on a monthly basis in eight gas monitoring wells (designated BLG- wells). Gas collected in these wells will be monitored for methane, carbon dioxide and oxygen (with remaining balance as nitrogen) in percent by volume using City of Bozeman’s landfill gas (LFG) analyzer. Monitoring results will be entered into a database and forwarded to City of Bozeman and DEQ - Solid Waste Bureau following each monitoring event. Task 200 Additional Groundwater Monitoring Events - September 2020 and March 2021
Two additional groundwater monitoring events are included in this task order to provide for quarterly data for the year. This data will contribute to the continued assessment of the
performance of the remediation system. Groundwater monitoring will be conducted in wells LF-2, LF-3, MW-12, MW-17, MW-18, and MW-20.
The wells will be purged prior to sampling, have field parameters measured (including temperature, pH, specific conductivity, dissolved oxygen, and oxidation reduction potential), and have samples collected for volatile organic compounds (VOCs in accordance with Method 8260 low level). Two quality assurance/quality control (QA/QC) samples will be collected and prepared during this monitoring event. These will be 1) a duplicate sample collected at a monitoring site and submitted for VOCs in accordance with Method 8260 and 2) a trip blank prepared by Pace Analytical Laboratories, shipped with the sample bottles, traveling with sample bottles in the field, and returned to the laboratory for analysis of VOCs. Task 300 December 2020 Compliance Groundwater Monitoring The first groundwater monitoring event contained in this task order will be conducted in December
2020 as part of the routine groundwater monitoring at the Bozeman Landfill. Tetra Tech will perform groundwater monitoring in accordance with Tetra Tech’s Groundwater Monitoring Sampling Analysis Plan. Groundwater monitoring will be conducted in existing groundwater
monitoring wells or stations. The scope of the monitoring event will be similar to the typical June monitoring events but will have additional analyses for metals, cations, and nitrogen. A monitoring, sampling, and analysis matrix for the December 2019 monitoring event is presented in Table 2.
Tetra Tech will request reductions in the frequency of analysis for some parameters that have not been observed at the landfill in several years, in an effort to reduce costs.
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Task Order – 2020 to 2021 Groundwater and Methane Monitoring and Assessment Bozeman Landfill, Bozeman, Montana May 26, 2020
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Field parameter monitoring and collection of water samples will be conducted in 24 monitoring sites/wells as specified in Table 2. Water levels will be measured in all monitoring wells at the site. Wells will be purged prior to sampling. Field parameters including temperature, pH, and specific conductivity. Field parameters will generally be measured during and at the conclusion of purging the monitoring wells. The field parameters: dissolved oxygen and oxidation reduction potential will be measured if winter weather conditions are at or above freezing. Water samples will be collected and shipped to Pace Analytical Laboratories (in Billings, Montana) for analysis of constituents shown in Table 2. The scope of analysis includes many of the constituents listed in Appendix I, 40 CFR Part 258 (July 1, 2008) in ARM 17.50.1306. Table 2
also reflects DEQ approved changes to the monitoring schedule of specified monitoring wells. Five quality assurance/quality control (QA/QC) samples will be collected and prepared during the
December 2019 assessment monitoring event. These will be 1) three duplicate samples collected at selected monitoring sites and submitted for analysis of all constituents included in Table 2; 2) two trip blanks prepared by Pace Analytical Laboratories, shipped with the sample bottles,
traveling with sample bottles in the field, and returned to the laboratory for analysis of VOCs; and 3) one decontamination blank collected from decontaminated, non-dedicated sampling equipment. Task 400 June 2021 Compliance Groundwater Monitoring
A groundwater monitoring event will be conducted in June 2021 as part of the routine groundwater monitoring at the Bozeman Landfill. Tetra Tech will perform groundwater monitoring in accordance with Tetra Tech’s Groundwater Monitoring Sampling Analysis Plan. Groundwater monitoring will be conducted in existing groundwater monitoring wells or stations. A monitoring, sampling, and analysis matrix for the June 2020 monitoring event is presented in Table 1.
Field parameter monitoring and collection of water samples will be conducted in 26 monitoring sites/wells as specified in Table 1. Water levels will be measured in all monitoring wells at the site.
Wells will be purged prior to sampling. Field parameters including temperature, pH, specific conductivity, dissolved oxygen, and oxidation reduction potential will be measured at all monitoring wells/stations where water samples will be collected. Field parameters will generally be
measured during and at the conclusion of purging the monitoring wells. Water samples will be collected and shipped to Pace Analytical Laboratories (in Billings, Montana) for analysis of constituents shown in Table 1. The scope of analysis includes many of the constituents listed in Appendix I, 40 CFR Part 258 (July 1, 2008) in ARM 17.50.1306. Table 1 also
reflects DEQ approved changes to the monitoring schedule of specified monitoring wells. Five quality assurance/quality control (QA/QC) samples will be collected and prepared during the June 2018 assessment monitoring event. These will be 1) three duplicate samples collected at selected monitoring sites and submitted for analysis of all constituents included in Table 1; 2) two trip blanks prepared by Pace Analytical Laboratories, shipped with the sample bottles, traveling with sample bottles in the field, and returned to the laboratory for analysis of VOCs; and 3) one decontamination blank collected from decontaminated, non-dedicated sampling equipment.
The purchase of one dedicated pump is included in this monitoring event, in the event of failure of a dedicated pump. Currently, pumps are used in wells LF-3, MW-4, MW-5, MW-6, MW-6B, and MW-8C.
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Task Order – 2020 to 2021 Groundwater and Methane Monitoring and Assessment Bozeman Landfill, Bozeman, Montana May 26, 2020
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Task 500 Evaluate hydrogeology and refuse distribution in southeast corner of landfill The 2018/2019 Remedial System Evaluation Report (dated March 11, 2020) identified increases in VOC concentrations in groundwater in well MW-17, including the appearance of methylene chloride above Montana groundwater protection standards for the first time since a single occurrence in 2015. This indicates the need to improve landfill gas capture in the southeast corner of the landfill. This task will entail a brief evaluation into whether increasing air flow from nearby LFGES wells and/or installing one or two additional landfill gas extraction wells in that area will reduce VOC concentrations in groundwater in the southeast corner of the landfill. It will also evaluate the distribution of VOC impacted groundwater in the area in order to better understand the source of the VOC in MW-17. Tetra Tech will evaluate the source and distribution of the VOCs with particular focus on
methylene chloride. We see two possible scenarios: landfill gasses are not being fully captured by the LFGES (GW-20 was removed from the system to accommodate the convenience site), or landfill gasses are migrating offsite along the eastern property boundary, contacting groundwater
which allows phase transfer of VOCs, which subsequently migrate back onto the landfill site. Our analysis will include investigating the potential to adjust flows in nearby LFGES wells to affect a vacuum across a larger portion of the southeast corner of the property. This analysis will be based on the extent and thickness of refuse in the area. The possibility of installing a horizontal LFG well in the thin areas of refuse will also be evaluated. To evaluate the possibility that VOCs are reaching groundwater upgradient of well MW-17, an offsite, a new upgradient monitoring well will be evaluated. Tetra Tech will evaluate well logs from the following locations: SVE 8, -9, and -16, MW-5 and -17, BSV-9, and -13, BLG-1 and -2 and GW-10, -15, -19, -20 and -26 to identify interbeds, changes in lithology or other indications for preferential pathways for either landfill gas or groundwater. Based on this analysis, Tetra Tech will identify LFG, SVE, groundwater monitoring and methane
monitoring wells where landfill gas/soil gas can be collected to map the distribution of evaluate potential offsite migration of LFG along eastern boundary of landfill. Following sample collection and laboratory analysis we will compile this new data with existing methylene chloride data from
SVE or LFG gas samples. Typical sources of methylene chloride in landfills will also be researched and compared to historical information on past landfill disposal practices in this area of the landfill and possible degradation The data collected by this program will be used to identify if more groundwater monitoring wells are needed in the area to better understand the source of the VOCs observed in MW-17, if flow from existing LFG wells can be adjusted to increase the capture zone without pulling oxygen into the cell, and if new LFG wells are needed. The use of horizontal wells in areas of thin refuse will also be evaluated. Our recommendations will be submitted to the City, then based upon approval from the City, we will develop a scope of work for our recommendations. This might include developing specifications for drilling a monitoring well, modifying existing wells to act as LFG wells or installation of additional LFG wells. Tetra Tech will assist the City with contractor management, oversight and construction QC as needed. Task 600 Project Management, Statistical Analysis, and Reporting
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Task Order – 2020 to 2021 Groundwater and Methane Monitoring and Assessment Bozeman Landfill, Bozeman, Montana May 26, 2020
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Project management will include progress reporting, scheduling of personnel, preparation/calibration of monitoring equipment/meters, supplies procurement, and other related activities; communication with City of Bozeman and DEQ; data management; administration/ invoicing; and task order preparation for 2020 monitoring activities. Following the completion of each groundwater monitoring event and receipt of laboratory results, DEQ will also be notified, in a letter report, as to which monitoring stations have regulatory exceedances of VOCs, metals, and/or inorganic constituents. Groundwater monitoring data will be entered into the project database and two reports will be prepared for the June 2020 and December 2021 groundwater monitoring events. Note that the data for the June 2020 report will be collected under the existing Task Order for the 2019/2020 period. The June 2021 data collected under this Task Order will be compiled into a report under a subsequent Task Order for the 2021/2022 period. This is necessary due to the start of the
new fiscal year being just weeks after the June groundwater monitoring event is conducted, which does not provide adequate time for the report to be completed before the end of the fiscal year covered by this Task Order. A statistical analysis of analytical constituents exceeding the
groundwater protection or regulatory standards will be conducted in each of these groundwater monitoring events. The statistical analysis has been and will continue to be conducted in accordance with DEQ requirements (ARM 17.50.1305 (7-11)). In addition, a third remediation evaluation report will be prepared evaluating 2020 system data. The third remediation evaluation report will be briefer than previous reports since we have developed the tables, graphs and analyses necessary to assess remediation system effectiveness and there will be limited new analysis in 2020. The report will take a longer term look at the remediation system and develop a 5-year plan for system maintenance, equipment replacements and upgrades to assist the City in longer term budget planning. This report will be submitted to the City of Bozeman in early 2021 in time to develop recommendations for the City’s FY2022 budget setting process. It will also be submitted to DEQ, following City of Bozeman approval. PERIOD OF PERFORMANCE Assuming approval of this Task Order prior to the start of the 2020 fiscal year, Tetra Tech’s
anticipated schedule to complete the above described activities will be the following: Deliverable Completion Date
Methane Perimeter Monitoring July 1, 2020 to June 30, 2021
September Groundwater Monitoring September 30, 2020
December Groundwater Monitoring December 31, 2020
March Groundwater Monitoring March 31, 2021
June Groundwater Monitoring June 30, 2021
June 2020 Groundwater Monitoring Report September 30, 2020
December 2020 Groundwater Monitoring Report March 31, 2021
2020 Remediation System Evaluation Report March 31, 2021
Southeast Corner LFG recommendations November 1, 2020
COSTS
Estimated costs to complete the foregoing scope of services are in shown below:
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Task Order – 2020 to 2021 Groundwater and Methane Monitoring and Assessment Bozeman Landfill, Bozeman, Montana May 26, 2020
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Task Description Estimated Cost
Task 100 Perimeter Methane Monitoring $6,342
Task 200 Quarterly Monitoring Events - March and September 2019’ $9,428
Task 300 December 2019 Groundwater Monitoring $21,485
Task 400 June 2020 Groundwater Monitoring $17,485
Task 500 Evaluate hydrogeology and refuse distribution in southeast corner of landfill $62,100
Task 600 Project Management, Statistical Analysis, and Reporting $40,060
Total $94,800
Our costs will be on a time and materials basis. A detailed cost estimate can be provided upon request. SPECIAL CONDITIONS: Execution of this Task Order constitutes acceptance of all terms and conditions contained in Tetra Tech’s Professional Services Agreement with the City of Bozeman, dated April 15, 2014. CLIENT: CONSULTANT:
City of Bozeman Tetra Tech By: By:
Printed Name: Printed Name: Kirk A. Miller Its: Its: Senior Project Manager Date: Date:
NOTICE OF CONFIDENTIALITY This Task Order (including attachments) contains information confidential to Tetra
Tech, Inc., its subsidiaries, and subcontractors. It is intended only for City of Bozeman to consider Tetra Tech providing professional services at the Bozeman Landfill. Any other use is prohibited, without the prior written consent of Tetra Tech.
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