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Home My WebLink About15.B.3. Shakopee High School Infiltration System Cost Participation JS:6~3, CITY OF SHAKOPEE Memorandum TO: Mayor & City Council Mark McNeill, City Administrator FROM: Bruce Loney, Public Works Director SUBJECT: Shakopee High School Infiltration System Cost Participation DATE: September 6, 2005 INTRODUCTION: Attached to this memo is a memorandum from Todd Hubmer and Todd Witkowski of WSB & Associates on infiltration system cost participation and justification for the City of Shakopee. Also attached is a letter from Jon McBroom, Shakopee School District Superintendent, in regard to the cost of the infiltration system on the high school project and their comments in regard to the infiltration system. This agenda item is for Council to authorize the stormwater trunk funds to be expended for the regional or multi-site infiltration system, and to direct staff to modify the fee schedule to recoup the cost of infiltration system and future developments. BACKGROUND: The City of Shakopee's staff along with its hydraulic consultant, WSB & Associates, Inc., has been working with the Shakopee School District #720 and their engineer on a ponding and infiltration system that would serve the high school site and other sites in the City of Shakopee. As mentioned, previously, a memo is attached from WSB & Associates, Inc. on the justification for a regional stormwater system in this vicinity. The main reason being that the soils at the high school site are ideal for an infiltration system and could accommodate a high infiltration which could be used throughout the region. The cost for the School District to construct the infiltration system is $145,014.00. The administration, engineering and other indirect costs that the City has incurred in developing this infiltration system is estimated to be an additional 25%. Also, from the analysis, the City's share of the infiltration system cost is 83.9% of the total cost, while the School District is responsible for the remaining 16.1 %. In the WSB & Associate's analysis, the infiltration system would provide approximately 165 acres of new impervious area for future development that could be infiltrated in this regional system. The cost per acre of those 165 acres would be approximately $922.00 or approximately 2.1 cents per square foot of new impervious area. As mentioned previously, the soils in the area below the bluff line are predominately sandy or sandy loam soils which are ideal for infiltration of stormwater, after the stormwater has been treated in the stormwater pond area. "Clean" water would then infiltrate through the infiltration system into the ground. By infiltrating in one large ponding area, the City will have less maintenance cost and will have easy access to the high school ponding site versus many multiple infiltration sites located in future developments. The School District would also like to reserve future infiltration system credits for future School District's site that will be coming on line in the future for their additional school facilities. Per the letter :from Jon McBroom, it is estimated that the school district would like to reserve 75 acres for future school projects. Also attached to this memo is a drainage map of the area that is in the vicinity of the Countryside development and Shakopee High School. ALTERNATIVES: 1. Approve a motion authorizing the City to reimburse the School District for its share of the regional infiltration ponding system in the amount of $121,667.26, and direct staff to revise the fee schedule to include an infiltration ponding fee for developments using the regional ponding system. 2. Do not approve this expenditure at this time. 3. Make a motion to reserve 75 acres of development site acreage for the School District to be used in future school projects using the infiltration credits generated by the regional pond on the new high school site. 4. Table for additional information. RECOMMENDATION: Staff recommends Alternative No. 1 and No.3, to authorize the Stormwater TrUnk Funds for the regional infiltration system, and to revise the fee schedule to include a fee for developments to purchase infiltration system credits associated with the regional ponding infiltration system. Staff believes this is a good cooperative effort between the School District and the City. The regional infiltration pond will be able to serve other developments in the future that are in more difficult infiltration areas. ACTION REQUESTED: 1. Approve a motion authorizing the City to reimburse the School District for its share of the regional infiltration ponding system in the amount of $121,667.26, and direct staff to revise the fee schedule to. include an infiltration ponding fee for developments using the regional ponding system. 2. Make a motion to reserve 75 acres of development site for the School District to be using future school projects using the infiltration credits generated by the regional pond on the new high school site. ~~ Public Works Director BUpmp ENGRl2005PROJECT/17TH -15-791lNFIL TRA TION SI1AKOPEE Superintendent: Jon McBroom PUBLIC SCHOOLS Business Manager: Mike Burlager District Office Human Resources Manger: Shaleen Roth Mr. Bruce Loney City of Shakopee August 29, 2005 Dear Mr. Loney, This letter will serve as a letter of agreement regarding the infiltration system in the pond at the new high school site. The cost ofthe infiltration system is $145,014.62. We agreed upon the WSB recommendation ofa City 83.9% share ($121,667.26) and District 16.1 % share ($23,347.34). I understand that you will be taking this recommendation to the council in September. I will approve the system with the contractor and get them started, so it does not delay our project. Upon Council approval of the sharing agreement, we can sign off on this letter and detennine a time frame for the City to reimburse the District for their share of the system. I also request, as part of this agreement, that the City reserve 75. acres of infiltration credit for the School District to be used with future school building projects. This assumes that the infiltration capacity the City is securing by sharing in the cost of the infiltration system will be used for future developments in the City. Thanks for you work on this project. I believe it will pay dividends for the City and School District into the future. For the City: For the School District: Date: Date: 505 Holmes St. S. . Shakopee MN 55379 952)496-5101 . fax: (952)4445-8446 AN EQUAL OPPORTUNITY EMPLOYER TTY: (952)496-5006 ~ WSB & Associates, Inc. Infrastructure I Engineering I Planning I Construction 701 Xenia Avenue South Suite 300 Minneapolis, MN 55416 Tel: 763-54F4800 Fax: 763-54 H 700 Memorandum To: Mr.lJruce Loney, City of Shako pee From: ..-.--- . t.... ToddB.Hubmer, P.B. I ~ I Ted Witkowski Date: August 29, 2005 Re: ShakopeelIigh School Infiltration System Cost Participation and Justification City of Shako pee, MN WSB Project No. 1281-81 Based on our reviewofthe anticipated annexation areas to the City of~hakopee, Sc{)tt County Watershed. Management. Organization rules,.. and Minnesota Pollution.Control. Agency NPDES rules, 'Yeofferth~follo\Vingjustification for a regional storm waterinfiltratioIlsystem in the vicinity of the newShakopee High School: "-", "'--~ " ".,.-<: , .,-.," -,'".',,-- . . . " '. , 1. The.niailltenaIlce, inspection and monitoring of a single regionalillfilt]"atibt1.syst~mwili.. reduce future operation and maintenance costs to the City of Shakopee. ". Monitoring a single facility over many multiple facilities will provide added value to the City. 2. The location of the proposed infiltration system is easily accessible by City crews for future operation and maintenance with little disturbance to adj acent residences or interruption of high school activities. 3. The soils atthe High School site are ideal for an infiltration system. The clay soils located south of the High. School site contain limited potential for infiltration. 4. The proposed regional infiltration systelllhas the capacity to infiltrate approximately 8.1 acre/feet of storm water runoff. The High School site is required to provide .1.3 acre-feet of infiltratioIl forthe future fully developed condition of the High School property. The remaining 6.8 acre-feet ofstorm water runoff volume credit provides the capacity to. infiltrate approximately 165 acres of new impervious area for future development within thewatershed.This equates to550 acres ofland being developed into residential land uses with 30% being impervious area. , " ,:: -', "::,;: . " ~'_: "":-"-":"--,0' . "_:: "," ,'. :" ,--.'--__:'., . . . ,- " ',-' i- " . . - -'.. ....'.-.. . ,-: -'_< _:", : , ',"':---,':_,-,' .,. , ," --, ',- .... .............:'-.: TheCityof Shakopee Storm Water Trunk Fee could be increasedtoincorporate the cost of providing the regional infiltration system for developments within the City of Shakopee. Based on an initial review, it would appear that the storm water trunk fess K:\01281-81\Admin\Docs\MEMO - bloney - 082905.doc Minneapolis I St. Cloud Equal Opportunity Employer Mr. Loney Page 2 of2 would be increased less than one (1) penny making this system very cost effective for both the City and future developers within the Jackson Township area. 6. Incorporating infiltration into the High School ponding areas will assist the City of . .... Shakopee in meeting the NPDES requirements for non-degradation that are anticipated to be issued this fall. The current draft rules indicate that infiltration will be a key component ill reducing runoff volumes. For the reasons stated above we recommend that a regional infiltration system be constructed within the High School ponding areas. The cost of the regional infiltration system should be reimbursed through future storm water trunk fees. If you have any questions, please call me at (763) 287-7182. kw K:loI 28 I -8 I !Admin IDocslMEMO - b/oney - 082905.doc I 0 15,00 , seAL E IN L LEGEND c::J COUNTRYSIDE DEVELOPMENT - 178 ACRES 11II SHAKOPEE HIGH SCHOOL - 90 ACRES .. 840 ACRES 16 ACRES c D 118 ACRES 0> D 29 ACRES ~ u 1>1 233 ACRES I iJ) I I 2969 ACRES <( - 0 ,- (J) +- :c; :c x w ,- U 0 Drainage Area to High School & Countryside Dev. u ,- m A 701 Xenia Avenue South, Suite 300 "" , ro WSB Minneapolis, MN 55416 Shakopee, Minnesota SHAKOPEE 0J www.wsbeng.com (5 ,- Q...~ - - "" ~~~iate8,Irt(;. 763-541-4800-Fax7G3-5llf-1700 Date: April, 2005 INFRASTRUCTURE, ENGINEERING PLANNINa CONSTRUCTION WSB Project No. 1281-79