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HomeMy WebLinkAboutItem 06.jevi'T l Date: 12 March 2014 Item No. APPROVAL OF AN ENGINEERING SERVICES AGREEMENT WITH BARR ENGINEERING CO. FOR GROUND WATER MODELING AND WELL SITING Proposed Action Staff recommends adoption of the following motion: Move to approve an engineering services agreement with Barr for groundwater modeling and well siting. Approval of this agreement enables Barr Engineering Co. to evaluate the siting for Wells 20, 21, and 22 and the effect pumping will have on source water aquifers. Overview In 2013, Short Elliot Hendrickson Inc. completed a comprehensive water supply plan update for the City. The plan looked at existing water utility facilities and looked at future system needs based on anticipated growth. The recommendations from that plan included 10 new water supply wells. This agreement with Barr Engineering Co. will look at the siting for the first 3 of those wells and determine the best locations and best sources of supply for the wells. Specifically, Barr Engineering Co. will evaluate what will be the best aquifer for installation of Wells 20, 21, and 22 with a view to avoiding well interference with other public and private wells and model the effects of the City's pumping on the aquifer at current and future demand levels. The result of the work completed by Barr Engineering Co. will assist the City in placing future water supply wells in the best location and aquifer to support City needs and maintain the viability of groundwater resources. Cost. of engineering services is $35,200.00. Primary Issues to Consider • Are these services necessary? Yes, to properly locate and install wells the City needs to understand the hydrology affecting the local aquifers and the effect pumping the additional wells will have on both public and private wells using the aquifer. Supporting Information • A cop of the Barr rin . agreement is. attached. Christop . etree Public Works Director Financial Impact: $35,200 Related Documents (CIP, ERP, etc.): Notes: Groundwater modelinq Budgeted: Yes Source: Water Trunk Funds 2014 - 2018 Capital Improvement Plan and well resourceful. naturally. BARR engineering and environmental consultants February 21, 2014 Mr. Chris Petree Public Works Director City of Lakeville 18400 Ipava Avenue Lakeville, MN 55044 Re: Groundwater Modeling of Future Water Demand Scenarios Dear Mr. Petree: Per your request, this letter is a proposal and definition of scope of services that Barr Engineering Co. (Barr) will provide to the City of Lakeville (City). The services to be provided are generally described as a study to evaluate the siting of wells 20, 21 and 22 and the effect projected pumping to meet future City water demand may have on the source water aquifers used by Lakeville. The services include groundwater modeling to assess the effect projected pumping in 2020, 2030 and 2050 may have on the viability of the Prairie du Chien -Jordan (PDCJ) aquifer and preparation of a report summarizing the findings of the work. This letter is also intended to serve as a work order to be completed according to the terms of our master agreement between Barr and the City. This letter includes: • Project Understanding • Project Team • Assistance Provided by the City of Lakeville • Scope of Services • Cost • Project Schedule Project Understanding This Scope of Services is based on the following project understanding: • The City is planning to meet future water demand and is currently planning for the installation of Wells 20, 21, and 22. The City is interested in evaluating the potential effects on the PDCJ aquifer due to pumping required to meet projected 2020, 2030 and 2050 water demand. Concerns regarding the long term viability of the PDCJ aquifer have been raised due to groundwater modeling previously conducted by the Metropolitan Council's Environmental Services Division (MCES) and groundwater levels that show a declining trend in regional aquifers. Barr Engineering Co. 4700 West 77th Street, Suite 200, Minneapolis, MN 55435 952.832.2600 www.barr.com Chris Petree Public Works Director February 21, 2014 Paae 2 As part of this study Barr will 1) evaluate whether proposed Wells 20, 21 and 22 can be installed in the PDCJ aquifer or if one of the wells would need to be installed in the deeper Tunnel City - Wonewoc (TCW) aquifer to avoid well interference and 2) review the results of the modeling of the effects of pumping to meet projected 2030 and 2050 water demand on the PDCJ and TCW aquifers in the Twin Cities Metropolitan Area completed by MCES in 2010 using Metro Model 2. Model scenarios will include proposed Lakeville Wells 20, 21 and 22 in the PDCJ aquifer and a scenario that includes proposed Well 22 in the TCW aquifer (as the City currently plans). Multiple modeling runs will be performed for this study. One will include current demands to simulate the incremental increase by only installing wells 20 -22, while additional runs will be included that simulate future demands. In those runs, we will include any additional wells required to meet projected future Lakeville demands as well as increase demands in other cities commensurate to what is needed to meet their demands. The City's 2013 Comprehensive Water Plan Update completed by SEH will be used to guide selection of new well locations for the modeling of future pumping. Metro Model 3 (an updated groundwater model for the Twin Cities metropolitan area Barr recently completed for MCES) will be used for this study. Finally, the work will be summarized in a report that includes tables and figures to assist you in communicating the work to your City Council or others who may need to approve budgets. The scope of services presented below is based on the following assumptions. Please note that this is not a complete listing of all assumptions, just those most critical to the work and the cost estimate. • Based on the 2013 Comprehensive Water Plan Update, new wells analyzed are assumed to be completed in the PDCJ or TCW aquifer. • Barr will identify potential new well locations based on the 2013 Comprehensive Water Plan Update completed for the City by SEH. These locations will be provided to the City for review before any model scenarios of future pumping are run. • No additional field data will be gathered for this study. • The City will provide Barr with water demand projections for 2020, 2030 and 2050 (if available). • Barr recently completed Metro Model 3. This model is a MODFLOW groundwater model of the Twin Cities metropolitan area that Barr developed for MCES. This model includes additional hydrogeologic detail not included in the older Metro Model 2. Metro Model 3 will be used without modification, other than adjusting pumping rates for Lakeville wells and high capacity wells within five miles of Lakeville. Project Team Barr proposes to utilize staff who have been involved with the most recent groundwater studies performed for Lakeville, including your wellhead protection planning. Key Staff dedicated to this project will include: • Brian LeMon, PE - Barr's principal -in- charge; Brian will be responsible for overall project quality and client satisfaction. In addition, Brian will be the primary project contact. Chris Petree Public Works Director February 21, 2014 Paqe 3 • John Greer, PG - Barr's project manager and lead hydrogeologist/groundwater modeler • Evan Christianson, PG — Hydrogeologist/groundwater modeler. Evan will assist John Greer with the groundwater modeling scenarios. We will use other Barr staff as needed to assist the key staff with completing project tasks as efficiently as possible. Assistance Provided by the City This proposal is based on the assumption that the City will provide the needed information requested by Barr to perform the tasks required to meet the stated goals. Once the project is initiated, and following the project kickoff meeting, a full list of data needed will be sent to the City. At this time we. expect that the following data/tasks will be provided by the City: 1. Provide Barr with historic annual water demand and well pumping data for the period 2011 — 2013. 2. Provide Barr with the most current projected water demands for 2020, 2030, and 2050 or ultimate water demand (if different than the 2030 projection). 3. Provide Barr with the most current population projection for 2020, 2030, and 2050 or ultimate population projection (if different than the 2030 projection). 4. Review of the preliminary list of prospective well locations for PDCJ and TCW wells developed by Barr prior to any modeling scenarios being run. 5. If needed, assist Barr in obtaining future demand and well location information from nearby communities whose wells are most likely to have an impact on Lakeville water supply. Scope of Services The scope of services is further described below. Task 1 Kickoff Meeting Following approval of this scope of work we will schedule a kickoff meeting with you. The purpose of the kickoff meeting will be to: • Review proposed well locations, • Review projected water demands and population projections, • And, if needed, refine the scope defined in this document to make sure it meets your needs. Deliverables from Barr to City: A meeting agenda, minutes from the meeting and a revised scope, schedule, and budget if needed. Deliverables from the City to Barr: Data from the list above. Chris Petree Public Works Director February 21, 2014 Paae 4 Task 2 Water Demand Analysis The City's 2013 Comprehensive Water Plan Update includes population and water demand projections for 2030 as well as projected annual average growth rates for 2020 and 2030. Barr will take this data and use it to develop projected future water supply demands for the years 2020, 2030 and 2050. If the City's ultimate population and water demand projections are the same as the 2030 projections, Barr will work with the City to develop a 2050 annual water demand projection based on available demand and population projections and the City's current per capita water demand. Once the future demands are calculated Barr will work with the City to divide the future demand between existing and proposed wells for use in the groundwater flow modeling effort. In addition to this, Barr will contact nearby communities whose wells are likely to have the greatest impact on Lakeville and verify with them what their planned future demand is for 2020, 2030 and 2050 and also where future wells are planned to be constructed. This will be compared to the rates and well locations used by MCES in their previous work. Information provided by the neighboring cities in this effort will be assumed to be more current and accurate than that used by MCES if there is a discrepancy. Results of this analysis will be compiled into tables and figures for the final report. As part of this task we will also work with you to develop the planned location of all future wells to be modeled to supply Lakeville's demands. Deliverables from Barr to City: Tables and figures to be included in the final report completed under Task 4. This will include a snap of proposed future well locations. Task 3 Future Pumping Scenarios With the water demand analysis and preliminary well site selections complete, we will move to evaluation of the effects of future pumping on the PDCJ and TCW aquifers. A baseline steady state scenario using the annual average pumping rate for each of the City's existing water supply wells for the period 2009 -2013 will be run using Metro Model 3. For this baseline scenario, no changes beyond updating the pumping rates for regional and City's wells and refining the model grid in the vicinity of Lakeville will be made to Metro Model 3. The results of the future pumping scenarios described below will be compared to the results of the baseline scenario. Three steady state future demand scenarios will be modeled: 2020, 2030 and 2050 water demand. For each scenario, it will be assumed that the existing City wells will pump at their annual average rates for the period 2009 -2013, except for Wells 3 and 7. Well 3 is out long term and Well 7 is classified as an.emergency well so it is assumed that neither well will pump in the future demand scenarios. The City's 2013 Comprehensive Water Plan Update projects that ten new wells (Wells 20 -29) will be installed by 2030. Therefore, both the 2030 and 2050 scenarios will include all ten of these new wells. For each scenario, the difference between the average annual demand for the period 2009 -2013 and the future scenario's projected demand will be distributed uniformly among the new wells. Available 2030 and 2050 pumping projections for Chris Petree Public Works Director February 21, 2014 Pacae 5 non - Lakeville municipal wells used by MCES for their previous modeling of projected 2030 and 2050 water demand in the metropolitan area will be used to simulate projected future demands of other cities in the region. In addition, if projected land use for 2020, 2030 and 2050 is available, the recharge boundary condition in the groundwater model will be updated to account for the projected changes in land use from current conditions. Each of these scenarios will be run using Metro Model 3. For the results of each of these future pumping scenarios the following analyses will be done: • Average annual drawdown for future demand with new wells in place as compared to the baseline scenario. • Comparison of the future pumping scenario drawdown to the corresponding scenario results previously presented by MCES. We will also use the groundwater model to evaluate whether proposed Wells 20, 21 anc 22 can all be installed in the PDCJ aquifer or if one of the wells will need to be completed in the deeper TCW aquifer to avoid well interference issues. Both steady state and transient scenarios will be run as part of this evaluation. The steady state scenarios will be as follows: • Proposed Wells 20, 21, and 22 will be added to the baseline model with all three wells in the PDCJ aquifer. Each well will be assumed to pump at the highest individual annual average pumping rate for any of the existing City wells in the PDCJ aquifer during the period 2009 -2013. This configuration for Wells 20, 21, and 22 will be modeled for the current demand scenario as well as for the 2020, 2030 and 2050 scenarios. • Proposed Wells 20, 21, and 22 added to the baseline model with Wells 20 and 21 in the PDCJ aquifer and Well 22 in the TCW aquifer. Wells 20 and 21 will be assumed to pump at the highest individual annual average pumping rate for any of the existing City wells in the PDCJ aquifer during the period 2009 -2013. Well 22 will be assumed to pump at the highest annual average pumping rate for Well 18 (the only existing City well that pumps from the TCW aquifer). This configuration for Wells 20, 21, and 22 will be modeled for the current demand scenario as well as for the 2020, 2030 and 2050 scenarios. The transient scenarios will be as follows: Proposed Wells 20, 21, and 22 added to the baseline model with all three wells in the PDCJ aquifer. All existing and proposed City wells in the PDCJ aquifer will be assumed to pump at 1,000 gallons per minute continuously for a period of four weeks. The rate at which the wells pump at will be confirmed with. the City so that it approximates conditions observed by the City during heavy summer use conditions. This configuration will be modeled for the current demand scenario as well as for the 2020, 2030 and 2050 scenanos. Chris Petree Public Works Director February 21, 2014 Paae 6 Proposed Wells 20, 21, and 22 added to the baseline model with Wells 20 and 21 in the PDCJ aquifer and Well 22 in the TCW aquifer. All existing and proposed City wells in the PDCJ aquifer will be assumed to pump at 1,000 gallons per minute continuously for a period of four weeks. Well 18 and proposed Well 22 will be assumed to pump continuously at the Well 18 capacity rate for a period of four weeks. The rate at which the wells pump at will be confirmed with the City so that it approximates conditions observed by the City during heavy summer use conditions. This configuration will be modeled for the current demand scenario as well as for the 2020, 2030 and 2050 scenarios. Deliverable: A report describing each scenario and the comparisons to the baseline scenario along with maps that show the results for each scenario (see Task 4 below). The report will also include recommendations for future work needed to better define trigger points for when additional work will be needed related to water supply planning. In effect, this will be a preliminary decision tree and road map to finishing out your water supply as you move to the future so that you understand when additional future action is needed on your part to reduce the risk of problems with your wells. Task 4 Prepare Project Report Barr will summarize the results of the work performed in a report that will be submitted to the City. A DRAFT report will be submitted to the City for review. Any comments received from the City will be addressed in the final report. Deliverables: The DRAFT report will be submitted to the City for review electronically in .pdf format either via our FTP site or on CD. The final report will be provided to the City electronically on CD. Paper copies of the report can be provided upon request but are not included in our estimated project cost. Cost The tasks listed in this subagreement will be performed for a lump sum cost not to exceed $35,200 without prior approval from the City. Bills will be sent once every 4 weeks according to Barr's standard billing schedule. Project Schedule The intention of this project is to have the work described in this subagreement completed within 140 days after notice to proceed is received from the City. Chris Petree Public Works Director February 21, 2014 Paqe 7 If the terms of this subagreement are acceptable to the City of Lakeville, please date and sign in the space provided below. Keep one copy for your records and return the other to Barr Engineering Co. If you have any comments or questions, please contact me at 952- 832 -2774. Sincerely yours, BARR ENGINEERING COMPANY Brian K. LeMon Its Vice President Accepted this _ day of , 201 CITY OF LAKEVILLE LIM Its EADocmnents\Barr Work\Proposals \Lakeville \Lakeville Future Drawdown Scenarios Proposal.docx