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HomeMy WebLinkAboutAECOM Proposal No. 572170 AECOM 920.235.0270 tel ASCOM 558 North Main Street 920.235.0321 fax Oshkosh,Wisconsin 54901 October 31,2016 Mr.John Ferris,PE Civil Engineer Supervisorri �,�� City of Oshkosh - 215 Church Avenue Oshkosh,Wisconsin 54903-1130 Subject: Contract Documentation for the Johnson Avenue Watershed Storm Water Management Plan Project for the City of Oshkosh,Wisconsin AECOM Proposal No.OPP-572170 Dear Mr.Ferris: Please find attached the necessary documentation to execute the agreement between the City of Oshkosh and AECOM Technical Services,Inc.(AECOM)for completion of the Johnson Avenue Watershed Storm Water Management Plan project. The attachments are described as follows: • Scope of Services for the Johnson Avenue Watershed Storm Water Management Plan • Authorization Form Services described in this proposal will be performed on a time-and-expense/unit-cost basis. Based upon the below scope of services,and discussed with the City of Oshkosh,the estimated budget for this project to provide Storm Water Management Plan services to the City of Oshkosh is$126,420. The project will be performed in accordance with the 2016 Negotiated Fee Schedule and the April 2009 Negotiated Terms and Conditions between AECOM and the City of Oshkosh,which are expressly incorporated into,and are an integral part of,contract for professional services. AECOM can begin providing these services immediately upon receipt of the signed Authorized Form (attached). Please indicate your acceptance of this proposal by having authorized individuals of the City execute the attached Authorized Form and return it to our Oshkosh office. We appreciate the opportunity to provide these engineering services to the City of Oshkosh. If you have any questions regarding the attachments provided,please call Paul Timm at 920-716-1338 or Paul Drew at 414-944-6152. ncerely yours, �,, /J P(/i/t/ bucvj _P I F.Timm Paul D.Drew, EP K—f � unt Man er Project Manager Thomas J. tan,PE Senior Project Manager Attachments AECOM Scope of Services Authorization Form Cc:Tracy Taylor,City of Oshkosh Department of Public Works OPP-572170_Johnson Avenue Watershed Contract Documentation Proposal.docx Johnson Avenue Watershed Storm Water Management Plan Scope of Services 1. Collect survey information necessary to assist in the construction of the storm sewer network model. A. Utilize NAVD 88 vertical datum and NAD 1983 Ham Wisconsin CRS Winnebago County horizontal datum. B. Roadside ditches,including culvert crossings: i. Survey up to 15 primary culverts within the drainage system. Shoot upstream and downstream inverts and measure size and note material. it. For culverts under the railroad tracks,AECOM wit[work with the City to secure right of entry and flagman services. iii. Survey cross sections upstream and downstream of each culvert to represent the channel shape. Cross sections will be extended outside of the channel what is determined to generally be the top of slope or beyond. iv. Survey up to 10 additional roadside ditch cross section locations to aid in defining the drainage system, 2. Construct conveyance network model(XPSWMMTM).Utilizing"2D"modeling overland flow methodology. A. Model all storm sewer,and culvert segments 18 inches in diameter(or equivalent)and larger.Figure 1 shows the location of the storm sewer within the watershed. B. Incorporate existing storm water management facilities(public and private)into the model.Figure 2 shows the sites that have approved Drainage Plans on file. C. The City of Oshkosh will provide storm sewer and culvert GIS information to assist in the network building.The information contained in the GIS may be utilized without the need for field verification. D. The City of Oshkosh will provide tiff images of development Grading and Drainage Plans to assist in the input of existing detention facilities.These images typically do not contain a stage-storage table,but do contain contours which can be utilized to calculate the stage-storage information. E. The City of Oshkosh will provide tiff images of utility and paving plans,if needed and available. F. The City of Oshkosh will provide the LIDAR data necessary to utilize the"2D"modeling. G. The Lake Winnebago tailwater elevation to be utilized is 747.56. 3. Construct Watershed Characteristics. A. The City of Oshkosh will provide most recent GIS information relating to the impervious area for parcels within the city limits. B. The City of Oshkosh will provide GIS information relating to the land use characteristics for all parcels within the study area. C. The watershed boundary will initially be developed following the City's Johnson Avenue Subbasin delineations as shown on Figure 1. Following the initial model development, OPP-572170_Johnson Avenue Watershed Contract Documentation Proposal-dou AECOM 3 the potential interconnection between the Gallups/Merritts Creek Watershed and the drainage area immediately south of the Johnson Avenue watershed,particularly that area along W.Ripple Avenue will be evaluated and potentially force the expansion of the study area and watershed boundary limits to account for the interaction. The incorporation of major additional drainage areas and components(such as modeling the entire Gallups/Merritts Creek Watershed)is not included in this scope of work. D. The major sub-basins will be subdivided as needed in order to properly execute the model. 4. Execute Existing Conditions Hydrologic and Hydraulic Model A. Utilize Huff&Angel(Midwest Climate Center Bulletin 71)rainfall depths and distributions. B. Run and calibrate model with June 12-13,2008 rainfall amounts and soil conditions and compare with actual observed flooding conditions to fine tune model.The City of Oshkosh will provide the rainfall distribution based upon the Wittman Regional Airport recording station. C. Perform sensitivity analysis to determine which duration design storm is the most critical for conveyance system capacities(check the 30-minute,1-hour,2-hour,3-hour and 6- hour duration storm events). D. Utilize existing land use and coverage characteristics. E. Run model at the critical duration for the following design storm events: i. 1 year ii. 2-year iii. 5-year iv. 10-year v. 25-year vi. 50-year vii. 100-year F. Prepare color figures showing the maximum extent of flooding during each storm event and the June 12-13,2008 storm event.The figures shall be color coded to show depth of flooding(typical ranges utilized are:0.01'-0.25',.0.25-0.5',0.5'-1.0',and greater than G. Prepare table noting the flooding depth and duration for up to 15 locations for each design storm and for the June 12-13,2008 storm event.Locations will be determined through coordination with City Staff. 5. Evaluate Alternatives A. Review and coordinate(where appropriate)with previous studies within watershed and adjacent to the watershed. L 2000 Citywide Storm Water Management Study(Mead&Hunt). ii. 2008 Citywide Stormwater Management Plan and Ordinance Development(Earth UPROPOSA.\City of Oshkosh\CPP-572170_Johnson Ave Watershed contract Documentation\OPP-572170 Johnson Avenue Watershed Contract Documentation Proposal.dccc AECOM q Tech\AECOM). iii. 2014 Citywide Stormwater Management Plan Update(AECOM) B. Mitigation Goals: i. Keep runoff below the rim elevation in the 10-year design storm event. ii. Keep the peak water surface elevation less than 0.5-ft above the rim elevation during the 25-year design storm event. iii. Contain runoff within the right-of-way for up to the 100-year design storm. iv. Reduce Total Suspended Solids(TSS)and Total Phosphorus(TP) C. Develop a list of potential mitigation components. L Coordinate with City Staff to determine feasibility of potential components. ii. Utilize City approved list to develop up to three(3)mitigation alternatives. D. Mitigation alternatives may consist of a single component,or a combination of components.The components of the additional alternatives will be based upon discussions with City Staff during the review process. i. Alternatives analysis shall include executing the model at the critical duration for the 10- year,25-year,and 100-year design storm events. ii. Prepare table and/or figure showing the reduction in flooding for locations identified in 4.G. E. Analyze up to six(6)mitigation alternatives.The initial three(3)alternatives developed under 5.C.iii.above,and up to three(3)additional alternatives that will be developed in conjunction with City staff through the review and discussion process. F. Using WinSLAMM,evaluate how the potential flood mitigation alternatives can also enhance TSS and TP pollutant removal_ G. Prepare figures showing the locations and conceptual layouts for all alternatives and components of alternatives.If renderings are desired for the recommended alternative, they will be added via contract amendment at a later date. H. Prepare planning level cost estimates for all analyzed alternatives. L Coordinate with city staff for cost information to be used. I. Potential sanitary sewer and water conflicts shall be taken into account during the alternatives analysis.The City will provide available GIS information to assist in accounting for these potential conflicts. J. Potential utility conflicts other than listed above shall not be taken into account during the alternatives analysis. K. Coordinate with City Staff to recommend one alternative. 6. Execute Post-Mitigation Modeling(for the recommended alternative). A. Utilize existing land use and coverage characteristics unless otherwise directed and provided by the City. B. Run model at the critical duration for the following design storm events: L 1-year K\PROPOSAL\City of 0shkosh\OPP-572170_Johnson Ave Watershed Contract Documentaton\OPP-572170_John5on Avenue Watershed Contract Documentation Proposal.doex AECOM 5 ii. 2-year iii. 5-year iv. 10-year v. 25 year vi. 50-year vii. 100-year C. Prepare color figures showing the maximum extent of flooding during each storm event. The figures shall be color coded to show depth of flooding, D. Run model with June 12-13,2008 rainfall amounts and soil conditions. E. Prepare table and/or figure showing the reduction in flooding at the location identified in 4.G.for the June 12-13,2008 storm event. F. Using WinSLAMM,evaluate resulting potential TSS and TP pollutant reductions. G. Perform sensitivity analysis to determine which duration of 100-year design storm event is the most critical for detention facilities.Note the peak water surface elevation of this storm event for all detention facilities in addition to the other design storm events modeled. 7. Prepare detailed written report,including at a minimum: A. Executive Summary. KIPROPOSAL\City of OshkosMOPP-572170_Johnson Ave Watershed Contract Documentation\OPP-572170 Johnson Avenue Watershed Contract Documentation Proposal.doc \ \ ! ! ! ! § ! ! ! ! ! ! ! ! z ! ! ! ! ! • ! ; ! ! ! ; ! ! ; ! ! ! ! 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