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HomeMy WebLinkAboutResolution - 2012-R0055 - Amendment To Agreement - HDR Engineering - 01/26/2012Resolution No. 2012-ROO55 January 26, 2012 Item No. 5.12 RESOLUTION BE IT RESOLVED BY THE CITY COUNCIL OF "ITE CITY OF LUBBOCK: THAT the Mayor of the City of Lubbock is hereby authorized and directed to execute for and on behalf of the City of Lubbock, an Amendment No. 1 to a Professional Services Agreement between the City of Lubbock and HDR Engineering, Inc., and related documents. Said Amendment is attached hereto and incorporated in this Resolution as if fully set forth herein and shall be included in the minutes of the Council. Passed by the City Council on January 26, 2012 TOM MARTIN, MAYOR ATTEST: Rebe ca Garza, City Secretary APPROVED AS TC t_'ONTENT: Marsha Reed, P.E. Chief Operations Officer Aubrey Spear, . Director of Voer Utilities APPROVED AS TO FORM: gs/Amend-Agnnit-Professional Servs-HDR i_ngmcenng„res 112 1.11 Resolution No. 2012-ROO55 AMENDMENT No. 1 TO PROFESSIONAL SERVICES AGREEMENT This Amendment No. 1 to Professional Services Agreement ("Amendment") is entered into this 26th day of January, 2012, by and between the City of Lubbock (the "City"), a Texas home rule municipal corporation, and HDR Engineering, Inc. (the "Engineer"), a Nebraska corporation. WITNESSETH WHEREAS, the City and Engineer entered into a certain Professional Services Agreement, dated June 23, 2009, Resolution No. 2009-RO231 (the "Original Agreement"), wherein the City contracted with Engineer to perform activities related to the planning, evaluating, permitting, designing, constructing, and inspection of reservoirs and dams; WHEREAS, it has come to the attention of City and Engineer that certain Phase 2 activities in the scope of services of the Original Agreement are no longer desired by the parties; and WHEREAS, the City and Engineer now desire to amend the Original Agreement to substitute a revised portion of the scope of services that contemplates related, but originally unanticipated, work. NOW, THEREFORE, for good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged, the City and Engineer agree as follows: 1. The attached "Phase 2B - Hydrogeologic Evaluation of Lake 7" is substituted for all Phase 2B ("Post Reservoir Analyses") Tasks, Summary of Deliverables, and Project Schedule items listed and otherwise contained in Exhibit "A" to the Original Agreement, in relevant and corresponding part. 2. The attached "Phase 2B - Hydrogeologic Evaluation of Lake 7" is substituted for all Fees and Compensation items specific to Phase 2B ("Post Reservoir Amendment No. 1 to Professional Services Agreement City of Lubbock and HDR Engineering, Inc. Page I of 3 Analyses") that are scheduled and otherwise contained in Exhibit `B" to the Original Agreement, in relevant and corresponding part. 3. The Hourly Rate Schedule contained in the Original Agreement remains the same for the attached "Phase 2B — Post Reservoir Analyses" to the extent a fee schedule shall be required to calculate fees in connection with the revised Phase 2B activities. 4. All summaries, tasks, schedules, fees, deliverables, and other information specific as to "Phase 2B — Post Reservoir Analyses" listed or otherwise contained in Exhibits "A" and "B" of the Original Agreement are deleted and of no further force and effect. S. Except as amended hereby, all terms and conditions of the Original Agreement shall remain valid and subsisting as originally provided. IN WITNESS WHEREOF, the parties have executed this amendment by their duly authorized representatives as of the date first written above. IDR ENGINEERING, INC. Amendment No. I to Professional Services Agreement City of Lubbock and HDR Engineering, Inc. Page 2 of 3 CITY OF LUBBOCK �,�- Tom Martin, Mayor ATTEST: Rebe ca Garza, City Secretary APPROVED AS TO CONTENT: f /- /I �/ - � , , A Marsha Reed, P.E. Chief Operations Officer 7 Aubrey Spe :E. 77- Director outer Resources To WA / /�II,�4�� Amendment No. I to Professional Services Agreement City of Lubbock and HDR Engineering, Inc. Page 3 of 3 Resolution. No. 2012-R0055 City of Lubbock Phase 213 — Hydrogeologic Evaluation of Lake l Scope of Work (Revised) The HDR Team will perforin the professional engineering services described in this Scope of Work. The HDR Team includes: HDR Engineering, Inc (HDR); and Enprotec /Hibbs & Todd, Inc. (eHT). Services include the second phase of the preliminary engineering evaluation of the feasibility of constructing Lake 7, specifically a hydrogeological investigation to confirm the potential for leakage from the reservoir. Background The City is evaluating various water supply alternatives to meet the City's future water needs and those of its wholesale water customers. Lake 7 would develop a dependable supply by utilizing the City's "developed water resources," which consist of storm water collected within the City's playa lake system and discharged into Yellow House Canyon, groundwater pumped from beneath the Lubbock Land Application Site, and treated wastewater discharged into Yellow House Canyon that originates from Lake Meredith in the Canadian River Basin and groundwater from the Ogallala Aquifer. To take advantage of the City's developed water resources, Lake 7 would be built to impound and store the water. Lake 7 would be located southeast of the City, just upstream of Buffalo Springs Lake and F.M. 835. Preliminary plans call for the dam to be approximately 80- to 100 -feet (ft) high, composite construction, with a concrete center spillway section and earthen dams on each side. Several alternative sizes and configurations were considered in initial phase of the feasibility analysis, which is documented in a report that was delivered to the City in September 2011 . Conservation capacities of 8,000 acre-feet (acft), 13,000 acft, and 20,000 aeft are considered to provide estimates of the firm yield water supply that could be made available. A secondary purpose of the project would be to partially control and mitigate small, nuisance floods downstream of Lake 7. For each of the conservation storage capacities evaluated, an alternative, larger configuration was evaluated, whereby sufficient storage would be available to capture flood events having recurrence intervals of two years or less. In support of the Lake 7 feasibility analysis, preliminary geotechnical investigations were conducted by Fugro Consultants, Inc. (Fugro) to determine the extent of and to better understand the major geologic units at the proposed dam site. A limited amount of laboratory testing was conducted to characterize the engineering properties of the materials comprising the geologic ' HDR Engineering, Inc., Feasibility of Constructing the Proposed Lake 7, City of Lubbock, Texas, September 2011. 2 Fugro Consultant, Inc., Preliminary Geotechnical Investigation — Feasibility Evaluation of Lake No. 7, City of Lubbock, Texas, March 18, 2010. HDR Engineering, Inc. Page 1 City of Lubbock units encountered at the site. A total of four borings were drilled along the proposed dam alignment, consistent with the original conceptual design for the dam. The relatively limited preliminary geotechnical investigations performed by Fugro provided a substantial amount of information regarding the proposed site and its suitability for dam construction. Nearly all the findings revealed conditions that will make the design and construction of a dam at the site more challenging • than was initially assumed. The September 2011 feasibility report describes conceptual design features that would mitigate many of the challenges that have come to light based on the geotechnical results from the four preliminary borings. This proposed scope of work is intended to address the issues of lateral and vertical leakage of water that would impounded in the proposed reservoir. Organization of Scope of Work Under this Scope of Work, the HDR Team will perform hydrogeological and geotechnical evaluations to further determine the feasibility of constructing Lake 7. Task 1: The HDR Team will characterize the area surrounding the Lake 7 reservoir pool by accumulating existing hydrogeologic data and developing an initial groundwater flow model. The results from the initial model simulations will guide the location of up to eight (8) groundwater monitoring wells to be installed in Task 2. Task 2: The HDR Team will conduct a field investigation to refine estimates of the hydrogeologic characteristics of the strata surrounding the Lake 7 reservoir pool. Task 3: Using the additional information obtained in Task 2, the HDR Team will refine the groundwater flow model developed under Task 1, and use the model to estimate the extent of lateral leakage into the Ogallala Aquifer and underfloor through the valley floor and beneath the dam under several different reservoir operating scenarios. For the proposed scope, all deliverables will be in both "hard copy" and "electronic copy." Task 1. Characterize Site and Develop -Initial Model The potential for lateral leakage from the lake into the canyon sidewalls is a major consideration and unknown at this time. During Phase I of the Lake 7 feasibility analysis, groundwater was encountered at a depth that likely corresponds with the level of the adjacent North Fork of the Brazos River. Groundwater also occurs as seeps out of the Ogallala Formation from the canyon sidewalls that may be laterally transmitted through porous (sand and gravel) layers atop relatively harder (cemented) layers. Seeps out of the canyon sidewalls exist in several locations, including one on the V-8 Ranch property near the base of canyon at the proposed north abutment. Conceptually, the Ogallala Aquifer may function as a bank storage reservoir where water flows into the Ogallala for temporary storage _during the rising limb of inflow into the lake and the water returns from storage during the recession of the lake's stage. This may, in effect, actually increase the effective storage of Lake 7. However, the concern of lake water temporarily stored in the aquifer moving downdip and past Lake 7 remains. HDR Team will construct a new, local -scale groundwater model that will be used to estimate the magnitude for lateral leakage of Lake 7 into the Ogallala Aquifer, leakage around the abutments HDR Engineering, Inc. Page 2 City of Lubbock of the dam, and underflow beneath the dam. One of the uses of the model is to determine if the Comanche Peak Limestone is of sufficient thickness and composition to minimize seepage losses through the floor of the canyon beneath the proposed lake. Specific subtasks associated with this effort are as follows. Task 1.1 Review Hydrogcologic Data Relevant to Existing Dams near Lake 7 Research will be conducted to determine if existing reservoirs in the region have dealt with potential lateral leakage into the Ogallala Formation. Specific reservoir sites to be researched include Palo Duro, Buffalo Springs, and Ransom Canyon Reservoirs. Reports that analyze the groundwater flow system in the vicinity of the Ogallala Aquifer in the High Plains region will be reviewed and studied in context with water level and discharge data. Task 1.2 Review Groundwater Resource Reports and Compile Hydrogeologic Data Hydrologic reports, including the recent TWDB Groundwater Availability Model (GAM), will be reviewed to understand the occurrence and structure of major hydrogeologic units (Ogallala Formation, Comanche Peak, and Antlers Sand) in the vicinity of Lake 7. Other information of interest is estimates of aquifer properties, recharge, and discharge. Well and groundwater level data from the Texas Water Development Board (TWDB), High Plains Underground Water Conservation District (HPUWCD), USGS, or other agencies will be compiled for the area surrounding the proposed Lake 7. Data of particular interest include base of Ogallala Formation, lithology, recharge, pumping, and groundwater levels. Data will also be obtained from the City's monitoring of the Lubbock Land Application Site (LLAS). Task 1.3 Groundwater Model Development To gain a better understanding of the potential leakage into the Ogallala Aquifer and underlying formation and groundwater movement toward and away from Lake 7, a groundwater flow model using MODFLOW will be constructed. The framework of the model will include up to three members of the Ogallala Formation, Comanche Peak, and Antlers Sand. The model will extend sufficiently far to be beyond any significant effects of Lake 7. Discretization of the model area will include boundary conditions that are based on a conceptual understanding of the area hydrogeology. Calibration will be with recent (approximately last 10 years) water level data. Aquifer properties will be based on the TWDB GAM, available well data, reports, and results of studies in Task 1. Information collected and utilized in the model will be coordinated with ongoing work by other City consultants and staff monitoring groundwater conditions in the area. Preliminary sensitivity test simulations will be conducted with the model to guide the location of monitoring wells to be developed in Task 2. HDR Engineering, Lnc. Page 3 City of Lubbock Task 2. Field InvestiLyation of Local Hydro-aeoloeic Characteristics Guided by the results of the initial groundwater flow model, the HDR Team will conduct a field hydrogeologic investigation of the area surrounding Lake 7, which will include drilling test holes to better define the lithology and geology of the subsurface, conducting field tests in the test holes to refine estimates of aquifer permeability, and installing piezometers (monitor wells) to monitor groundwater levels in the area. Primary Task 1 deliverables will include a Hydroceologic Characteristics Summary Report. Subconsultant (eHT) will conduct the test drilling, field analyses and testing, and will install the monitor wells. Plans are to conduct the investigations at six (6) to eight (8) sites in the vicinity of the proposed Lake 7 dam. Specific subtasks associated with this effort are as follows. Task 2.1 Location of Test Sites Between six (6) and eight (8) test holes will be drilled and piezometers installed in the vicinity of the proposed dam site. Tentatively, six (6) sites are planned, with two of the sites located in the valley, and two on each of the banks. Based on the LLAS monitoring information identified in Task 1, test holes may not be needed on the north bank, allowing more holes to be located on the south bank. The additional two (2) sites are contingencies to investigate unusual conditions. The sites selected will need to be accessible with standard drilling and support vehicle equipment, assuming minimal clearing will be required. It is further assumed that the City of Lubbock will obtain necessary property access permissions with assistance from the HDR Team. Task 2.2 Survey Test Site Locations The proposed test site locations will be established by surveying the horizontal coordinates and surface elevations of each. Task 2.3 Drill and Sample Test Holes and Install Monitor Wells Test holes will be drilled with a light mud rotary rig to depths ranging from 50 to 150 feet. After the drilling has been completed, a monitor well will be installed in the test hole. The well will be constructed with two-inch diameter PVC. Screen intervals lengths will be determined in the field, based on the soil/rock conditions encountered, and the estimated depth to groundwater. Each screen interval will be surrounded by a filter pack material (e.g. sand) to facilitate hydraulic connection with the water -bearing zone. Well development will consist of purging and pumping to obtain a better hydraulic connection with the surrounding geologic materials. Monitor wells will be completed with above ground steel protective casing with locking covers. Placement and construction of the monitoring wells (diameters, screening intervals, etc.) will be coordinated with other monitoring work being conducted by the City so that the wells can be utilized for future monitoring activities to the extent practicable. The current fee estimate assumes specific construction features of the wells. To the extent that any individual well is modified from this assumed design, the HDR Team will notify the City in advance of any need to adjust the fee estimate for this project. HDR Engineering, Inc. Page 4 City of Lubbock Task 2.4 Borehole Logging During the drilling process, drill cuttings will be collected and studied to determine soil/rock stratigraphy and the presence of groundwater. Pertinent data, such as, difficult drilling conditions, loss of drilling fluid, and rock fractures or seams will be noted. Task 2.5 Single or Double Unlined Packer Tests After the drilling of the test hole has been completed, single or double unlined packer tests will be conducted to estimate the in-situ permeability of significant geologic stratum or strata of interest. Task 2.6 Record Groundwater Levels Groundwater levels in each of the piezometers will be recorded at four (4) consecutive monthly intervals. Task 2.7 Prepare Technical Memorandum A Hydrogeologic Characterization memo will be prepared and will include: • Stratigraphic, lithologic and hydraulic test data; • Calculation of water -bearing properties; • Initial assessment of the general water holding capability of the target impoundment area; and • The results of the field testing (included in an appendix). Task 3. Characterize Potential Underflow and Leakage from Lake 7 Task 3.1 Refine Groundwater Model After completion of the test drilling and field tests, the preliminary groundwater model will be refined with updated aquifer property and groundwater level data. Four (4) Lake 7 scenarios will be tested, including:. filling, long-term stable conditions, typical withdrawal cycle, and potential operational plan. While the model will not include any water quality components, the HDR Team will make determinations regarding how the hydrologic interaction between Lake 7 and the geologic strata intersecting the reservoir pool through the walls of Yellowhouse Canyon may affect the water quality of both. It is anticipated that since little mixing would occur in the interaction of the reservoir with local groundwater, that any effects would be minimal. Task 3.2 Prepare Technical Memorandum A memo addressing estimates of groundwater movement near the lake and dam will be prepared and will include: • Tabular or graphical summaries of aquifer properties and water level data; • Discussion on the development, calibration and application of the groundwater model; • Estimates of groundwater movement for the above scenarios; • Discussion of key findings; and • Recommendation as to the impact of any groundwater movement on the feasibility of Lake 7. HDR Engineering, Inc. Page 5 City of Lubbock Task 3.3 Present Findings to LWAC and/or Council The final results of all work related to leakage and underflow will be presented to the Lubbock Water Advisory Commission (LWAC). A PowerPoint presentation of the findings and conclusions of the work effort will be prepared. This presentation will be reviewed with City staff prior to presentation to the LWAC. This scope of work anticipates that two members of the HDR Team will attend the presentation in Lubbock and be available to answer questions. Deliverables include a PowerPoint presentation and associated boards and visual aids, including handout packages for the LWAC. The project budget includes an allowance for an additional presentation to the City Council, which can be scheduled following the presentation to the LWAC. Phase 2B — Schedule The following are estimated times for completion of the three tasks. The time to complete Task 1 is from notice to proceed. The time to complete Task 2 accounts for the four months of groundwater level monitoring, and follows completion of Task 2. The time to complete Task 3 follows completion of Task 2. Task Task Description Time for 1 Site Characterization and Development of Initial Model Completion 1 Site Characterization and Development of Initial Model 16 weeks 2 Field Investigation of Local Hydrogeologic 20 weeks 3 Characteristics $62,530 ' 3 Characterize Potential Underflow and Leakage from g weeks Lake 7 $251,630 Total Time to Complete Tasks 1 — 3 44 weeks Phase 2B — Fee Estimate The following table summarizes the fee estimated to be required to complete the above scope of work. Task Task Description Fee 1 Site Characterization and Development of Initial Model $53,100 2 Field Investigation of Local Hydrogeologic $136,000 Characteristics 3 Characterize Potential Underflow and Leakage from $62,530 ' Lake 7 Total Fee $251,630 HDR Engineering, Inc. Page 6 City of Lubbock