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Home My WebLink AboutAmendment to Professional Services Agreement with Tetra Tech, Soil Gas Investigation_Part7 Commission Memorandum REPORT TO: Honorable Mayor and City Commission FROM: Craig Woolard, Public Works Director Rick Hixson, City Engineer SUBJECT: Amendment to Professional Services Agreement with Tetra Tech Inc. for ongoing post-closure soil gas investigation at the Story Mill Landfill. MEETING DATE: February 24, 2014 AGENDA ITEM TYPE: Consent RECOMMENDATION: Authorize City Manager to sign. BACKGROUND: This winter air quality investigation work plan has been prepared for the purpose of evaluating the potential for vapor intrusion into residential structures in the Bridger Creek Phase 3 Subdivision and four residential structures in the Bridger Creek Phase 2 Subdivision during winter conditions. In addition, quarterly operation monitoring of mitigation systems installed by the City will be conducted. This work plan was prepared by Tetra Tech at the request of the City of Bozeman. Volatile organic compounds (VOCs) were discovered in soil gas at the south boundary of the Bozeman Landfill in 2012. Follow-up investigations have included a soil gas investigation in the Phase 3 Subdivision and air sampling of indoor, sub-slab, or crawlspace or outdoor locations. These samples have also been collected in four residential structures in the Bridger Creek Phase 2 Subdivision. Mitigation systems have been installed and are operating in 24 homes in the Bridger Creek Phase 3 Subdivision. Air quality information gained from this proposed monitoring event will contribute to the conceptual site model, the evaluation of the effectiveness of the mitigation systems (in homes where they exist) and provide preliminary information as to the temporal variation of VOCs in soil gas and in the sub-slab or sealed crawlspace locations. The evaluation of vapor intrusion in winter is considered by Montana Department of Environmental Quality (DEQ) to be the most optimal time period because homes are closed up and operating their heating systems. In addition, the ground is frozen reducing the escape of soil gas into the atmosphere. The costs in the attached task order cost are $58,363.68. These charges are for sample collection, analysis and reporting. 43 FISCAL EFFECTS: The entire project will be funded through the Solid Waste Landfill Closure/Post-Closure Fund. ALTERNATIVES: As suggested by the City Commission. Attachments: Task Order from Tetra Tech Inc. Report compiled on: 2/11/14 44 Task Order Work Plan for Winter Air Quality Investigation Bozeman Landfill Bozeman, Montana January 31, 2014 CLIENT: CONSULTANT: The City of Bozeman Tetra Tech, Inc. P.O. Box 1230 851 Bridger Drive, Ste 6 Bozeman, Montana 59711-1230 Bozeman, MT 59715 Attention: Mr. Rick Hixson Attention: Mr. Mark F. Pearson INTRODUCTION This winter air quality investigation work plan has been prepared for the purpose of evaluating the potential for vapor intrusion into residential structures in the Bridger Creek Phase 3 Subdivision and four residential structures in the Bridger Creek Phase 2 Subdivision during winter conditions. In addition, quarterly operation monitoring of mitigation systems installed by the City will be conducted. This work plan was prepared by Tetra Tech at the request of the City of Bozeman. Volatile organic compounds (VOCs) were discovered in soil gas at the south boundary of the Bozeman Landfill in 2012. Follow-up investigations have included a soil gas investigation in the Phase 3 Subdivision and air sampling of indoor, subslab, or crawlspace or outdoor locations. These samples have also been collected in four residential structures in the Bridger Creek Phase 2 Subdivision. Mitigation systems have been installed and are operating in 24 homes in the Bridger Creek Phase 3 Subdivision. Air quality information gained from this proposed monitoring event will contribute to the conceptual site model, the evaluation of the effectiveness of the mitigation systems (in homes where they exist) and provide preliminary information as to the temporal variation of VOCs in soil gas and in the subslab or sealed crawlspace locations. The evaluation of vapor intrusion in winter is considered by Montana Department of Environmental Quality (DEQ) to be the most optimal time period because homes are closed up and operating their heating systems. In addition, the ground is frozen reducing the escape of soil gas into the atmosphere. The information gained from this indoor air investigation will allow Tetra Tech to confirm or modify its conceptual model of soil gas transport. Tetra Tech’s current model identifies landfill gas migration directly from the Unlined Cell as the primary transport mechanism for VOCs into the adjacent residential neighborhood. The data from this investigation could also support the development and comparison of remedial alternatives during a Revised Corrective Measures Assessment (CMA) process within the Bozeman Landfill property. Mitigation systems have been installed in 26 homes in the Bridger Creek Phase III neighborhood, to date. These need to be monitored quarterly for the first year of operation, semiannually for the second year, and annually thereafter. This work plan includes four operational quarterly monitoring events. 45 Task Order – Winter Air Quality Investigation Bozeman Landfill, Bozeman, Montana January 31, 2014 Page 2 of 4 SCOPE OF WORK This work plan proposes one monitoring event consisting of the following: Field Investigation The collection of air samples will be conducted by Tetra Tech field personnel from nine Phase III homes and four Phase II homes. Two field crews will be used to shorten the sample period. The types of air samples collected will consist of the following: ■ A subslab or sealed crawlspace air sample will be collected from each residence. In residences with operating mitigation systems, one air sample will be collected from the mitigation system exhaust pipe. This sample will be considered the subslab air sample or sealed crawlspace air sample. In residences that do not have a mitigation system, one sample will be collected from the previously installed vapor monitoring point. ■ One indoor air sample will be collected from the lowest living level of each residence. We do not feel it is necessary to collect the multiple indoor air samples as was the case during previous sample events. ■ One ambient outdoor air sample will be collected during each day that indoor air sampling is being conducted in a residence. ■ Air samples will be collected from methane monitoring wells BLG-3, 4, 5, and 10 and nine soil gas probes (to be selected from primarily, the shallower depth intervals of BSV- 1 through 12). ■ Ten percent of the sampling train will consist of duplicate samples. ■ Samples will collected in 6-liter SUMMA canisters with 24-hour and ½-hour flow controllers, depending on whether the sample is an indoor or ambient and system exhaust or subslab sample. ■ Sampling equipment will be obtained from Eurofins Air Toxics Laboratories (ATL). Each piece of sampling equipment (canisters and flow controllers) will be individually certified by ATL for TO-15 SIM method analysis. ■ Following sample collection, canisters and flow controllers will be shipped back to ATL for laboratory analysis of selected VOCs in accordance with the TO-15 SIM method. The VOCs to be analyzed will be consistent with past indoor air sampling. ■ Work will be conducted in accordance with Tetra Tech’s Sampling and Analysis Plan prepared for air monitoring activities conducted on the Bozeman Landfill project. As mentioned above, air in indoor, subslab, and system exhaust has been collected for laboratory analysis on a scheduled basis (i.e. following mitigation system installation). This work plan will assume that residences with air sampling conducted in January 2014 or scheduled to have the post-mitigation air sampling conducted in February or March, will not be included in this event because those samples already qualify as satisfying DEQ’s winter 46 Task Order – Winter Air Quality Investigation Bozeman Landfill, Bozeman, Montana January 31, 2014 Page 3 of 4 monitoring requirement. Table 1 provides information on the status of mitigation systems for Phase 3 and the homes that would be sampled as part of this work plan. It is proposed that all of the monitoring take place during the month of February and efforts will be made to collect the samples during as short a time period as possible. Samples collected assume that homeowners will be present and cooperate with this investigation. Mitigation System Operational Monitoring Mitigation systems have been installed in 26 homes in the Bridger Creek Phase III neighborhood, to date. The operation of these systems will be monitored quarterly for the first year of operation. Monitoring consists of a visual inspection of the entire system, measurement of vacuum at the extraction point and any vacuum monitoring points installed in the home, identification and repair of leaks in the structure slab or the system itself, and inspection of the exhaust or discharge point to verify no air intakes have been located nearby. This work plan includes four operational quarterly monitoring events. System repairs will be made as needed. The scope of system repairs (e.g., repair cracked pipes, replace damaged monitoring points, replace faulty fans) is difficult to predict, therefore, for costing purposes we have developed a rough estimate. Project and Database Management and Reporting Tetra Tech’s management team for this work plan will consist of Kirk Miller as the Project Manager and Mark Pearson as the Assistant Project Manager and field team leader. Project management will consist of sampling equipment and materials procurement; site preparation; client, public, and regulatory liaison; review/approval of invoicing, and scheduling Tetra Tech personnel and access to residences among other activities. Data management will include validation of analytical data and entry of the analytical data into the project database (Microsoft Access) along with all of the other air quality data for the project. This will in turn support generation of data tables, maps and GIS analysis as needed throughout this work plan and other phases of the project. Reporting Individual results letters will be prepared for each homeowner using a similar format as the post mitigation letters currently being produced. These results will also be incorporated in an air quality investigation report that includes all post mitigation sampling results, when such report is produced later in 2014. The quarterly operational monitoring will entail just a few vacuum measurements and a few notes about system status. Since, that data does not need to be validated, we propose to create a system inspection form that is left with the homeowner at the time of the inspection. This form will include the vacuum data, status of system, any repairs made or recommended, any cracks grouted close etc. Schedule Tetra Tech’s anticipated schedule to complete the field portion of the winter air quality investigation in February will be dependent upon approvals from the City of Bozeman, the availability of sampling equipment from ATL and homeowner access. Following completion of the field activities, the air quality results letters would be submitted to homeowners within six weeks sample collection. The performance monitoring will be conducted at the same time as the indoor air sampling, then on a quarterly basis thereafter. 47 Task Order – Winter Air Quality Investigation Bozeman Landfill, Bozeman, Montana January 31, 2014 Page 4 of 4 Compensation Estimated costs to complete the foregoing scope of services are not to exceed $58,364. A breakdown of these proposed expenditures is contained in the attached cost estimate. The services will be conducted on a time and materials basis. 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 January 3, 1994 and Amendment Nos. 1, 2, 3, and 4 of the Professional Services Agreement dated July 31, 1995; January 1, 1996; March 17, 1997; and December 10, 2001, respectively. CLIENT: CONSULTANT: City of Bozeman Tetra Tech By: By: Its: Its: Sr. Project Manager Date: Date: January 31, 2014 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. 48 Table 1 Residence Count for Winter Air Quality Investigation Bozeman Landfill, Bozeman, Montana Resident Site ID Mitigation System Installed /Operating Post-Mitigation Samples Collected Collection of Post-Mitigation Samples in 2013 Collection of Post-Mitigation Samples in 2014 Residences to be Sampled in February 2014 Bridger Creek Subdivision Phase 3 Moriarity SAI-1 √√ Steckmest SAI-2 √√√ Keller Trust SAI-3 √√√√ Beebe SAI-4 √√√ Vanuka SAI-5 √√√√ Cook SAI-6 √√√ Olsen SAI-7 Out of town until April 2014 Rostad SAI-8 √√√ Bottcher/Leep SAI-9 √√ (1) Kitowski SAI-10 √√√√ Hokanson/Spitzer SAI-11 √√√ Fischer SAI-12 √√√√ Wilson SAI-13 √√√ McNally SAI-14 √√ Kelleher SAI-15 √√√√ Bowen SAI-16 √√√√ Daenen SAI-17 √√√√ Verellen SAI-18 √√√√ McClaughry SAI-19 √√ (1) Woloszyn SAI-20 √√ Perkins TI-1 √√√ Hoy TI-2 √√ Russell TI-3 √√ Slate TI-4 √√ McGovern TI-5 √√√ Rydberg CI-1 √√ (1) Bowman CI-2 √ (1) Schutter SMI-1 √ Bridger Creek Subdivision Phase 2 Letang AI-1 √ Bottcher AI-6 √ Racow AI-7 √ Carne AI-11 √ Number of Residences :13 (1): Mitigation system under construction, post-mitigation sampling pending Tetra Tech 49 ESTIMATED BUDGET WORKPLAN FOR WINTER AIR QUALITY INVESTIGATION AND MITIGATION SYSTEM OPERATIONAL MONITORING BOZEMAN LANDFILL BOZEMAN, MONTANA Date Submitted: 1/31/2014 Field Investigation Field Work Units Rate Cost Project Manager/Senior Hydrogeologist, per hour 4 $150.00 $600.00 Assistant Project Manager/Hydrogeologist, per hour 24 $95.00 $2,280.00 Environmental Scientist, per hour 80 $95.00 $7,600.00 Field Technician, per hour 80 $65.00 $5,200.00 Clerical, per hour 4 $55.00 $220.00 Subtotal $15,900.00 DIRECT COSTS Tetra Tech Vehicle Mileage, per mile 608 $0.56 $340.48 Per Diem and Lodging, per person per day 10 $140.00 $1,400.00 Sampling Media and Analytical Costs 6L SUMMA Canister, certification & rental, each 53 $55.00 $2,915.00 24-hr Flow Controller, certification & rental, each 20 $20.00 $400.00 1/2-hr Flow Controller, certification & rental, each 33 $15.00 $495.00 TO-15 Analysis, each 53 $140.00 $7,420.00 Client Specific EDD, each 4 $5.00 $20.00 Duplicate Sampling T, certification & rental, each 4 $8.00 $32.00 Sampling Disposables - Miscellaneous, each 33 $10.00 $330.00 Helium Meter, per week 1 $375.00 $375.00 Helium, estimate 1 $300.00 $300.00 Miscellaneous Shipping, estimate 1 $100.00 $100.00 Lab Sample Shipping (overnight to lab), estimate 1 $1,325.00 $1,325.00 TetraTech Subcontractor Markup (10%)$1,371.20 Subtotal $16,823.68 TOTAL $32,723.68 Mitigation System Operational Monitoring (4 events) Project Manager/Senior Hydrogeologist, per hour 16 $150.00 $2,400.00 Assistant Project Manager/Hydrogeologist, per hour 80 $95.00 $7,600.00 Field Technician, per hour 80 $65.00 $5,200.00 Administrative Personnel, per hour 12 $55.00 $660.00 Subtotal $15,860.00 TOTAL $15,860.00 Field Equipment Vacuum meter, per day 20 $25.00 $500.00 Vehicle, mileage 500 $0.60 $300.00 TetraTech Subcontractor Markup (10%)$80.00 Subtotal $880.00 TOTAL $16,740.00 Project Management, Database Management and Data Validation Project Manager/Senior Hydrogeologist, per hour 24 $150.00 $3,600.00 Assistant Project Manager/Hydrogeologist, per hour 24 $95.00 $2,280.00 Environmental Chemist, per hour 24 $110.00 $2,640.00 Database/GIS Analyst, per hour 28 $95.00 $2,660.00 Administrative Personnel, per hour 4 $55.00 $220.00 Subtotal $11,400.00 TOTAL $11,400.00 Reporting (indoor air and operational monitoring) Tetra Tech 50 Project Manager/Senior Hydrogeologist, per hour 16 $150.00 $2,400.00 Assistant Project Manager/Hydrogeologist, per hour 40 $95.00 $3,800.00 Environmental Scientist, per hour 24 $110.00 $2,640.00 Database/GIS Analyst, per hour 24 $95.00 $2,280.00 Field Technician, per hour 32 $65.00 $2,080.00 Administrative Personnel, per hour 12 $55.00 $660.00 DIRECT COSTS Photocopies, estimate 800 $0.10 $80.00 Reprographics, estimate 6 $50.00 $300.00 Subtotal $14,240.00 TOTAL $14,240.00 TOTAL OF ALL TASKS $58,363.68 Tetra Tech 51