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HomeMy WebLinkAbout3. Prior Lake Outlet Channel Restoration Project and Revised Agreement 3. , CITY OF SHAKO PEE Memorandum TO: Mayor & City Council Mark McNeill, City Administrator FROM: Bruce Loney, Public Works Director SUBJECT: Prior Lake Outlet Channel Restoration Project and Revised Agreement between the Cities of Prior Lake and Shakopee, Prior Lake - Spring Lake Watershed District and the Shakopee Mdewakonton Sioux Community DATE: June 7, 2005 At the June 7, 2005 City Council work session, prior to the City Council meeting, staff will present a power point presentation on the Prior Lake Outlet Channel Restoration Project with a future cooperative agreement revision to the Joint Powers Agreement that currently exists. This agreement will have a cost sharing proposal for the construction and maintenance of the channel for all entities involved. Representatives from the Watershed District, the Cities of Shakopee and Prior Lake and more recently Shakopee Mdewakanton Sioux Community (SMSC) have been meeting for approximately five years to revise the existing Joint Powers Agreement, which was entered into in the early 1980's. A redesign of the outlet channel is necessary due to development and future uses of the channel by all entities and the fact is that the existing channel is not adequate to meet the needs of the Cities and the Watershed District in the future. Each entity has areas that drain into the channel and even different uses of the channel from a hydraulic perspective. Several meetings have been held in the past year, which have been more productive that the meetings in the previous fours years, to bring about a potential draft agreement which will be entered into between the Cities of Prior Lake and Shakopee and the Watershed District. The Watershed District would have a separate agreement with the SMSC. The design for the channel has been completed in concept with a bio-engineered channel for aesthetics and to match into the natural environment with armored portions of channel, as necessary, to control erosion and provide stability of the channel. Preliminary costs have been generated, based on this concept design, and these costs have been separated into eight segments of the channel from the outlet of Prior Lake to Blue Lake in Shakopee. Various models between the government entities have been reviewed and completed to a point where the various government agencies can agree on certain flows from each government area. The Technical Advisory Group has come to an agreement on a cost sharing percentage for each area with runoff goals and a cost sharing for each segment can then be calculated. Additionally, costs have been generated for the maintenance of the channel for on-going operation of this channel and cost sharing for each government entity. Finally, a construction phasing and annual costs have been generated for each partner that will use the channel and these costs will be presented to the Council in a draft form on June 7, 2005. The purpose of this agenda item is to bring the Council the information, which has been formulating for several years, and has made significant progress in the past few months It is important for the Council to enter into an agreement for ultimate channel improvements as there is development that is occurring in this area that will utilize the channel. Cost sharing with other entities will keep the City of Shakopee's costs to a minimum, yet serve all partners to their desired needs. At this point this memo is strictly informational to the Council as to the status of the revised Joint Powers Agreement. If there are any questions or Council wishes to provide staff direction as we move forward in this agreement that would be appropriate. Bruce Loney Public Works Director BL/pmp ENGR/EMPLOYEEFOLDER/PPENNINGTON/COUNCIL/OUTLETCHANNEL Prior Lake Outlet Channel Restoration Project Cooperative Agreement Summary of Technical Advisory Group Meetings and Cost Share Proposal May 2005 Presentation Outline Outlet Channel Project Need and Principles Project Challlenges Technical Advisory Group Technical Advisory Process, Summary and Recommendations Model Evaluation Construction cost share Maintenance cost share Construction phasing JPA language Current Status of JPA agreement [including cost share] Estimated construction schedule Questions/Discussion . Outlet Channel Project Need Outlet Channel operated under existing JPA since early 1980's In 2003, partners completed a study of existing and future needs and the conceptual re-design of the Outlet Channel Re-Design of the Outlet Channel is necessary because: Development in the watershed leading to: Forcasted increase in frequency of lake outlet discharges Cities need for a reliable outlet of storm water Need to address existing erosion Opportunity to improve water quality aesthetics and channel habitat Outlet Channel Project Principles A durable Outlet Channel that meets partners needs Fair distribution of costs among partners Based on use of the channel includes construction and maintenance Cost responsibility begins at point of entry into the outlet channel and extends downstream Meet easement needs through development process Outlet channel design is based on ecological principles Design & maintenance based on ecological principles Native vegetation /bioengineering meets channel needs at a resonable cost, while making the channel a local amenity & improving habitat and aesthetics Acceptable to regulatory entities 2 JPS Challenges Patners have different needs Differences between hydrologic and hydraulic models constructed by partners Construction phasing, and timing of cooperative agreement to meet construction schedule Developing a fair cooperative agreement Modeling Challenges Intended to use one H&H model to determine cost share Each partner had their own H&H model Each model was created for different purposes and showed different results The cost to merge all the new information from each partner's model was >$50,000 No guarantee of satisfactory results Approach Convened Technical Advisory Group to discuss modeling differences Devised a cost share approach that relies on existing information Technical Advisory Group Prior Lake Spring Lake Watershed District Shannon Lotthammer, District Administrator, Ed Matthiesen, District Consulting Engineer, Rebecca Kluckhohn, Consulting Engineer City of Prior Lake Steve Albrecht, City Engineer Shakopee Mdewakanton Sioux Community Stan Ellison, Land Manager; Scott Walz, Hydrologist; Dave Pogg, Consulting Engineer City of Shakopee Bruce Loney, Public Works Director; Todd Hubmer, Consulting Engineer Technical Advisory Group Process Evaluated partner's models Used existing data to explore cost share options Technical advisory group met to review findings Additional information developed between meetings to address technical group questions Mettings held March 17, 2005 April 15, 2005 May 3, 2005 Meeting Highlights March 17, 2005 Discussed parnter's models Discussed overall elements of a fair cost share breakdown Reviewed potential cost share scenarios April 15, 2005 Reviewed proposed partner runoff goals Discussed basis for construction cost share Developed recommendation for construction cost share May 3, 2005 Discussed basis for maintenance cost share and reviewed analysis Developed recommendation for maintenance cost share Discussed annual costs and construction schedule Summarized next steps (JPS language and review process) Modeling Discussion Modeled areas The red shaded area shows the PLSLWD Outlet Channel Model extent and sub-watersheds Prior Lake Outlet modeled at 65 cfs continuous outflow. Note that this is a maximum flow rate Modeled Areas Partner land areas tributary to Prior Lake Outlet Channel Locations for comparison Blue Lake Inlet McKenna Rd (Blue Lake Channel) . Summary of Model Comparison Model input: The models are close on total areas and curve numbers, though individual sub-watershed delineations differ. Model Output: The model results are very different, runoff volumes and flow rates differ between each model because of Differences in the model computations Assumptions Base information Purpose Construction Cost-Share Discussion Cooperative Agreement Funding Breakdowns could be based on: Runoff Rate, Runoff Volume, Area Contributed by each partner (The Cities of Prior Lake and Shakopee, Prior Lake Spring Lake Watershed District and The Mdewakanton Sioux Community) . Cooperative Agreement Funding Breakdowns could be based on: Runoff Rate: Runoff Volume: Modeled flow rates Modeled volume (differ based on model Expected runoff volume assumptions etc.) using Curve Numbers and Runoff Rate Goals. areas from the model, and For example, Shakopee has a SCS runoff methodology runoff goal of 0.1 cfs/acre. for the chosen storm. Multiplied by the area covered by the city, this translates into a flow rate. Multiply it by a period of time and we get a volume. Potential Scenarios (For Discussion) PLSLWD Model - Outlet Channel SMSC Prior Lake (Trust City of Spring Lake Lands Prior City of Watershed Percent of Total Cost Only) Lake Shakopee District Total Original Proposal 0% 10% 45% 45% 100% Option 1: Volume* 6% 29% 46% 19% 100% Option 2: Flow Rate Goals** 7% 32% 55% 6% 100% *100 year event, plus 65 cfs through outlet for 5 days (based on curve numbers) **Rate goal x area no duration factor TAG Discussion The Technical Advisory Group agreed: The potential benefits of additional modeling did not justify the costs There is no perfect answer, and the goal is to develop a cost share that everyone finds reasonable To employ a simplified approach using runoff rate goals (specified by each partner) and areas to determine the cost share Runoff Rate Goals Provided by Partners Partner Goal Prior Lake Spring Lake 65 cfs constant outflow, vary the Watershed District duration [10 days] City of Shakopee 0.1 cfs/acre for the Direct Tributary Area and Sub-watersheds south of Dean Lake 0.33 cfs/acre for all areas of the city entering the channel north of Dean Lake City of Prior Lake 0.17 cfs/acre [from model] Shakopee Mdewakanton Sioux 0.05 cfs/acre from both Fee & Community Trust lands Used the idea of a duration factor to calculate construction cost-share by segment. Results: Segment based construction Cost Share Segment PLSLWD City of City of Prior SMSC Total Shakopee Lake 1 $650,170 $0 $55,910 $2,819 $708,900 2 $363,996 $14 $43,739 $1,751 $409,500 3 $263,196 $7,626 $71,046 $1,482 $343,350 4 $245,211 $204,966 $92,715 $68,807 $611,700 5 $331,122 $353,990 $125,199 $93,290 $903,600 6 $161,364 $162,936 $61,013 $51,937 $437,250 7 $218,445 $378,201 $82,595 $70,309 $749,550 8 $102,459 $182,674 $38,740 $32,977 $356,850 Percentage of Cost Share 51.7% 28.5% 12.6% 7.2% 100% Total $2,335,963 $1,290,407 $570,957 $323,373 $4,520,700 Notes: Does nto include easement acquisition (need at least 75' centered on the channel). Capital costs are based on est. $150/ln foot of channel, which reflects our experience so far with the project. Maintenance Cost-Share Discussion 12 Basis for Maintenance Cost Share Estimate unit costs Considered breakdowns for wet & dry years annual precipitation and measured outlet flows from one wet year and one dry year. Compared to the breakdown for construction Discussed annual and partner costs by segment Developed recommendation Estimated Maintenance Costs (unit costs) $250,000 maintenance fund; funded over 5 year period; replenished annually based on work done in segment (replenishment should account for inflation). $10/lf of channel annually for the first 5 years of vegetative establishment & maintenance $5/lf of channel annually after the first 5 year period Notes 1. $10/lf is based on a 150-foot wide buffer (ideal width, 75 is minimum); and a cost of $3,000/acre for 0-5 year maintenance - this is included in construction costs 2. $5/lf is based on the same width, and a cost of $1,500/acre for 5+year maintenance 13 Estimated Maintenance Costs per Partner Dry Construction Stakeholders COnditions Wet Conditions Agreement Prior Lake Spring Lake 8% 54% 52% Watershed District City of Shakopee 31% 19% 29% City of Prior Lake 46% 18% 13% Shakopee Mdewakaton 15% 9% 7% Dry Condition assume 15% of precipitations as runoff volume. Wet conditions assume 35% of precipitations as runoff volume. This runoff volume is compared to the outflow volume from Prior Lake That value is based on flow measurements, days of flow, & gates open Simplify the agreement by using the same cost share that was used for construction Construction Phasing and Annual Costs Segment 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 1 Prior Lake to D C(winter M1 M1 M1 M1 M1 M2 M2 M2 M2 CR 42 05-06) 2 CR 42 to Pike D C(winter M1 M1 M1 M1 M1 M2 M2 M2 Lake inlet 06-07) 3 Pike Lake Inlet D C(winter M1 M1 M1 M1 M1 M2 M2 to Pike Lake 07-08) Trail 4 Pike Lake Trail D C(winter M1 M1 M1 M1 M1 M2 M2 to CR 16 07-08) 5 CR 16 to D C(winter M1 M1 M1 M1 M1 M2 M2 M2 M2 Deans Lake 05-06) outlet 6 Deans Lake D C(fall M1 M1 M1 M1 M1 M2 M2 M2 M2 Outlet to TH winter 05- 169 06) 7 TH 169 to TH D C(winter M1 M1 M1 M1 M1 M2 M2 M2 101 06-07) 8 TH 101 to Blue D C(winter M1 M1 M1 M1 M1 M2 Lake inlet 07-08) Notes D=Design, C=Construction, M1=0-5 yr. maintenance, M2, 6+ yr maintenance 14 Annual Costs for Each Partner 2005 2006 2007 2008 2009 2010 PLSLWD $904,095 $475,501 $398,591 $222,551 $181,567 City of Shakopee $434,533 $267,753 $209,692 $173,369 $100,299 City of Prior Lake $192,996 $114,185 $116,049 $59, 875 $44,379 SMSC $119,424 $68,427 $57,847 $38,326 $25,135 Total $1,651,048 $925,845 $780,980 $494,120 $351,380 2011 2012 2013 2014 2015 Partner Total PLSLWD $155,731 $117,642 $81,281 $81,281 $77,865 $2,696,105 City of Shakopee $86,027 $68,796 $49,103 $49,103 $43,014 $1,481,688 City of Prior Lake $38,064 $29,993 $20,323 $20,323 $19,032 $654,198 SMSC $21,558 $16,623 $11,878 $11,878 $10,779 $381,677 Total $301,380 $233,055 $162,585 $162,585 $150,690 $5,213,669 Note Annual costs shown here include capital and maintenance costs but not any easement acquisition costs Capital construction cost estimates are based on $150/linear foot of channel Annual Costs for Each Partner $1,000,000 PLSL WD $900,000 City of Shakopee $800,000 City of Prior Lake $700,000 SMSC $600,000 $500,000 $400,000 $300,000 $200,000 $100,000 $- 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 . TAG Recommendations Employ a simplified approach using runoff rate goals and relative drainage area to determine the cost share Calculate cost share by segment Only apply cost share from the point where partner's stormwater enters the channel and downstream Use same formula for construction and maintenance cost-share to simplify application Establish $250,000 fund for "hard" maintenance with reimbursement mechanism Plan/budget annually for vegatation maintenance Meet annually in March to discuss project plans and needs (both construction and maintenance) Current Status of Cost Share Recommendation Technical Advisory Group recommends using a cost share breakdown for construction and maintenance based on tributary land area and new development standards set by each Partner (runoff rate as a flow rate per area) The TAG also recommends meeting annually in March to review and budget for recommended work. Percent of Total Project Cost PLSLWD 51.7% City of Shakopee 28.5% City of Prior Lake 12.6% SMSC 7.2% 16 Current Staus of JPA Agreement PLSLWD will draft a revised agreement (May-June) JPA for the cities and the PLSLWD MOA for the SMSC and the PLSLWD (a separate agreement is necessary because under state law, SMSC cannot be a party to a JPA) PLSLWD attorney will review the agreements Draft revised JPA will be distributed to partners for review (July) Channel design and construction costs incurred while the JPA is under development will be reimbursed according to the cost-share agreement Current Status of Construction Schedule Proposed Construction Schedule by Channel Segment 1. Prior Lake to County Road 42: Winter 2005-2006 2. Country Road 42 to Pike Lake: Winter 2006-2007 3. Pike Lake Outlet to Pike Lake Trail: Winter 2007-2008 4. Pike Lake Trail to Country Road 16: Winter 2007-2008 5. County Road 16 to Deans Lake Inlet: Winter 2005-2006 6. Deans Lake Outlet to TH 169: Winter 2005-2006 7. TH 169 to TH 101: Winter 2007-2007 8. TH 101 to Blue Lake: Winter 2007-2008 17 Questions? Comments? Thank you!