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Receive Feasibility Report / Order Plans & Spec's for Armory Site Storm Drain Utility Improvements, City Project #238CITY OF ROSEMOUNT EXECUTIVE SUMMARY FOR ACTION CITY COUNCIL MEETING DATE: August 18, 1992 AGENDA ITEM:Receive Feasibility/Order Plans & Specs -Armory Storm Drain Utility, Prj. 238 pgEpARED BY: Bud Osmundson City Engineer/Assistant Public Works Director ATTACHMENTS: Resolutions, Feasibility Report 0 AGENDA SECTION: Old Business AGENDA NO ITEC A # 5 plpB; wvEp BY s previously been apprised of the,concep The Council has p site. public utilities required to serve the Armory report Th todays agenda item is to receivtloflplans and drain utilities and authorize preparation 'ect ;/f or the purpose of for the storm specifications for this pro? ro ect s based on the premise that construction The timing of the p i 7 in in late September or October this year. the Armory building will beg lace for the Armory before We should wait until all signatures are in p awarding any contracts for the utilities. Brian Bourassa, P.E., of OSM will be present the alternatives investigated. The executive feasibility report gives a brief exp lanation funding. the feasibility report for plans and specifications for to give an overview summary in the of the alternatives of and Staff recommends Project No. 238 this project. that the Council receive and orders preparation of RECOMMENDED ACTION: MOTION TO ADOPT A RESOLUTION PROJECTNNO. 238BILITY R REPORT, ARMORY STORM DRAIN UTILITY IMPR SPECIFICATIONS FOR THE MOTION TO ADOPT DRAIN UTILITION TY IERING PLANS AND MPROVE CITY PROJECT NO. 238. ARMORY SITE COUNCIL ACTION: Orr Schelen Mayeron & 0IM!x-, Associates, Inc. 2021 East Hennepin Avenue August 11, 1992 Minneapolis, MN 55413 612-331-8660 FAX 331-3806 Engineers Architects Planners Honorable Mayor and Council sur<,evors City of Rosemount 2875 145th Street West Rosemount, MN 55068 Re: Armory Storm Drainage Improvements City of Rosemount City Project No. 238 OSM Project No. 4845.30 Dear Mayor and Council: Enclosed is the Feasibility Report for the Armory Storm Drainage Improvements. This report reviews stormwater facility improvements for the Armory Site Pond and Schwarz Pond. We would be happy to discuss this report with you at your convenience. Please call me at 378-6380 if you have any questions. Sincerely, ORR-SCHELEN-MAYERON & ASSOCIATES, INC. Brian J. Bourassa, P.E. Project Engineer dad enclosure cc: Mr. Bud Osmundson, City of Rosemount u CERTIFICATION SHEET I hereby certify that this plan, specification or report was prepared by me or under my direct supervision, and that I am a duly Registered Professional Engineer under the laws of the State of Minnesota. ""Brian J. Bourassa, P.E. Date: August 11, 1992 OSM Project No. 4845.30 Reg. No. 21816 Page i TABLE OF CONTENTS TITLE SHEET LETTER OF TRANSMITTAL CERTIFICATION SHEET ......................................... i TABLE OF CONTENTS ........................................... ii EXECUTIVE SUMMARY ........................................ 1 INTRODUCTION ............................................... 2 Authorization ............................................. 2 Data Available ............................................ 2 Background ............................................... 2 PROPOSED IMPROVEMENTS .................................... 3 Storm Drains .............................................. 3 Permits.................................................. 6 Right -of -Way and Easements .................................. 6 RECOMMENDATIONS .......................................... 7 FINANCING................................................... 8 Cost Estimate ............................................. 8 Funding.................................................. 8 PROJECT SCHEDULE .......................................... 9 APPENDIX OSM Project No. 4845.30 Page ii ARMORY STORM DRAINAGE IMPROVEMENTS ROSEMOUNT, MINNESOTA CITY PROJECT NO. 238 EXECUTIVE SUMMARY This report addresses the feasibility of providing stormwater facility improvements for the Armory Site Pond (Pond SCH 153) and Schwarz Pond (Pond SCH 151). The project is feasible from an engineering standpoint. The recommended project includes the construction of an 8.4 Ac -Ft pond which has an estimated project cost of $81,500.00. The funding for the project will come from the stormwater utility. The project will require approximately one month to complete. OSM Project No. 4845.30 Page 1 1. INTRODUCTION 1.1. Authorization - City Council authorized the preparation of the engineering feasibility report on August 20, 1991. 1.2. Data Available - Information and materials used in the preparation of this report include: • City of Rosemount Record Plans • City of Rosemount Aerial Photo/Topography Maps • City of Rosemount Drainage Plan - West Drainage Area - May 1989 • Rosemount Armory Site Plan 1.3. Background - The Proposed Armory Site is located in the SCH 153 subwatershed within the Schwarz Pond Drainage District (see attached drainage map). For the purpose of this analysis we considered this area to be fully developed. The City of Rosemount - Drainage Plan - West Drainage Area (May 1989) delineates the flow direction from SCH 153 (Armory Site) to SCH 151 (Schwarz Pond). The Drainage Plan also indicates that subwatershed SCH 152, located north of the Armory Site, flows into SCH 153. The pond within subwatershed SCH 151 is a land -locked pond. There is approximately 330 acres tributary to Pond SCH 151. According to the Drainage Plan the Normal Water Level (NWL) of Pond SCH 151 is 921.5. The most current City topographic maps show the existing water level for Pond SCH 151 to be 924.8 Directly south of Pond SCH 151 is Pond SCH 178. Pond SCH 178 is located on the Rosemount High School property and is approximately 35' from the existing building which has a low entry elevation of 930.2. According to the Drainage Plan the NWL for Pond SCH 178 is 924.8 and the High Water Level (HWL) is 935.0. During a critical storm event Pond SCH 178 act as one land -locked basin. In the past, critical storm events have produced flooding conditions at Rosemount High School. IOSM Project No. 4845.30 Page 2 L ti 2,. PROPOSED IMPROVEMENTS 2.1. Storm Drains - Storm sewer will be installed on the Armory Site as part of the Armory Building Bid Package. The proposed storm drainage improvements for the Armory Building Bid Package include the construction of 950 L.F. of storm sewer, catch basins, and a 2.4 Ac - Ft pond. No outlet is proposed for the Armory Site Pond with the Armory Building project. The cost of the storm drainage improvements for the Armory Building described above are not included in this report. We have reviewed four drainage alternatives for providing stormwater facility improvements for the Armory Site Pond (Pond SCH 153) and Schwarz Pond (Pond SCH 151). The four alternatives are described as follows and the corresponding Alternative Exhibits are located in the Appendix of this report. Alternative No. 1 - Increase the storage capacity of the Armory Site Pond to 8.4 Ac -Ft. It was assumed, for this alternative, that the Armory Site Pond would be constructed on the adjacent commercial parcels along State Trunk Highway No. 3 (S.T.H. No. 3). a This alternative would improve the flooding conditions at the Rosemount High School by eliminating approximately 37 acres (SCH 152 and 153) of drainage from Pond SCH 151. A 100 year - 10 day IOSM Project No. 4845.30 Page 3 The City of Rosemount Drainage Plan recommends that low floor elevations near land -locked basins be at least 5 feet above the basin's 100 year flood elevation. We used a 100 year - 10 day rainfall event to analyze this alternative. The managed NWL in this pond was assumed to be 956.0 and the HWL was calculated at 962.5. Any stormwater Pond SCH 151 from flooding over the HWL (962.5) will flow into the emergency overflow area located in the rear parking lot on the west side of the Armory Building. The proposed low floor elevation for the Armory building is 963.00. a This alternative would improve the flooding conditions at the Rosemount High School by eliminating approximately 37 acres (SCH 152 and 153) of drainage from Pond SCH 151. A 100 year - 10 day IOSM Project No. 4845.30 Page 3 rainfall event for this alternative would result in a HWL at Pond SCH 178 (Adjacent to Rosemount High School) of approximately 932.3. A berm could be constructed between the School and Pond SCH 178 to reduce the chance of flooding. Estimated Project Cost = $81,500.00 (Including Contingencies and Admin.) 1 The estimated project cost for this alternative does not include the costs for relocation of the existing businesses along S.T.H. No. 3, the acquisition or the parcels of the demolition of the existing buildings. Alternative No. 2 - Construct a gravity storm sewer outlet for the 2.4 Ac -Ft pond at the Armory Site, proposed to be graded as part of the Armory Site Building project. Approximately 1700 L.F. of 21" storm sewer would be constructed from the Armory Site Pond to the east, across S.T.H. No. 3 to Pond ERN 190 in Erickson Park. Pond construction for this alternative would not require the acquisition of the commercial parcels along S.T.H. No. 3. This alternative produces a HWL at the Armory Site Pond of 961.8. C� r IOSM Project No. 4845.30 Page 4 This alternative would have the same impact on Pond SCH 151 as in Alternative No. 1. However, the 21" storm sewer outlet for the Armory Site would also provide an outlet for a future storm sewer pumping system at Pond SCH 151. The City of Rosemount Drainage Plan lists the NWL for Pond ERN 190 at 920.8 and the HWL at 940.7. With this alternative assuming the same NWL at 920.8 the HWL for a 100 year - 10 day rainfall event was C� r IOSM Project No. 4845.30 Page 4 n t i i III calculated to be 935.9. The City of Rosemount Drainage plan lists Pond ERN 190 as a land -locked basin. Estimated Project Cost = $99,100.00 (Including Contingencies and Admin.) Alternative No. 3 - Construct a stormwater lift station and forcemain system at Pond SCH 151 that would pump 1.0 cfs of stormwater from Pond SCH 151 to the 2.4 Ac -Ft Armory Site Pond. As with alternative No. 2, construct a 21" storm sewer outlet from the Armory Site Pond to Pond ERN 190. This alternative would lower the HWL at Pond SCH 151, adjacent to Rosemount High School, to approximately 930.5. A berm would still need to be constructed in this area to provide the recommended two feet of "free -board" as stated in the Drainage Plan. Using a 100 year - 10 day rainfall event to analyze this alternative a HWL at Pond ERN 190 was calculated at 944.6. Estimated Project Cost = $217,800.00 (Including Contingencies and Admin.) Alternative No. 4 - Increase the storage capacity of the Armory Site Pond to 8.4 Ac -Ft. As with Alternative No. 1, it was assumed that the Armory Site Pond would be constructed on the adjacent commercial parcels along S.T.H. No. 3. Construct a 1.0 cfs lift station and forcemain system at Pond SCH 151 that would pump to the Armory Site Pond. Approximately 1700 L.F. of 18" storm sewer would be constructed from the Armory Site Pond to the east, across S.T.H. No. 3 to pond ERN 190 in Erickson Park. IOSM Project No. 4845.30 Page 5 G, 2.2. Permits - Permits will be required for this project from Mn/DOT for i work within the S.T.H. No. 3 right-of-way. 2.3. Right -of -Way and Easements - Permanent drainage and utility easements will be needed from the following parcels: 060-60 012-81 014-55 050-60 Temporary construction easements will also be needed from the parcels This alternative produces a HWL at the Armory Site Pond of 959.1. The HWL at Pond SCH 151 and Pond ERN 190 would be the same as those in Alternative No. 3. easementacquisition costs. Estimated Project Cost = $289,000.00 (Including Contingencies and Admin.) The estimated project cost for this alternative does not include the costs for relocation of the existing businesses along S.T.H. No. 3, the acquisition or the parcels of the demolition of the existing buildings. A gravity outlet from Pond SCH 151 to Pond ERN 190 was considered, however, the deep excavation (over 40') made this alternative cost prohibitive. 2.2. Permits - Permits will be required for this project from Mn/DOT for i work within the S.T.H. No. 3 right-of-way. 2.3. Right -of -Way and Easements - Permanent drainage and utility easements will be needed from the following parcels: 060-60 012-81 014-55 050-60 !J IOSM Project No. 4845.30 Page 6 Temporary construction easements will also be needed from the parcels along the project route. The estimated project costs listed in this report do not include- ncludeeasement easementacquisition costs. !J IOSM Project No. 4845.30 Page 6 a Site Pond will be constructed to Pond ERN 190 and Pond SCH 151 then could 3. RECOMMENDATIONS For this type of land use, Nationwide Urban Runoff Program (NURP) water We recommend Alternative No. 1 - Constructing an 8.4 Ac -Ft pond on the Armory Site. This alternative will initially provide the Armory Site with enough stormwater storage capacity to handle a 100 year - 10 day rainfall event, provided the water elevation in the land locked basin is not allowed to exceed elevation 956.0 except following significant rainfall events. It is anticipated the City will pump this basin within five days to lower its water elevation to 956.0 should the water in the basin exceed this elevation. As part of this recommendation it is also anticipated a future outlet for the Armory Site Pond will be constructed to Pond ERN 190 and Pond SCH 151 then could 1 t IOSM Project No. 4845.30 Page 7 be pumped to the Armory Site Pond. For this type of land use, Nationwide Urban Runoff Program (NURP) water quality standards require an open water area of about 4% of the direct drainage area to achieve removals of approximately 95% solids, 60% phosphorus and 40% metals such as lead and copper. The 8.4 Ac -Ft pond would have an open water area of 0.9 acres which is 6% of the direct drainage area and would meet NURP standards. 1 t IOSM Project No. 4845.30 Page 7 i 1 4. FINANCING 4.1. Cost Estimate - The cost estimates are based on 1991 and 1992 construction costs and includes a 10 percent contingency factor and related administrative costs. The administrative costs are estimated at 30 percent and include legal, engineering, interest and other administration. Detailed cost estimates can be found in the Appendix of this report. The following is a summary of the estimated project costs for each of the alternative described above: Alternative No. 1 .................................. $81,500 Alternative No. 2 .................................. $99,100 Alternative No. 3 ................................. $217,800 Alternative No. 4 ................................. $289,000 4.2. Funding - The entire project is proposed to be paid for by the stormwater utility. OSM Project No. 4845.30 Page 8 5.. PROJECT SCHEDULE The proposed schedule for the Armory Site Pond improvement is as follows: Approve Feasibility Report/Order Plans & Specifications ... August 18, 1992 Approve Plans and Specifications ................... September 1, 1992 Receive Bids and Award Contract .................... October 6, 1992 Begin Construction ................................. October, 1992 Complete Construction ................................ June, 1993 The above schedule is for constructing Alternative No. 1 - the 8.4 Ac -Ft pond only. OSM Project No. 4845.30 Page 9 ARMORY STORM DRAINAGE IMPROVEMENTS ROSEMOUNT, MINNESOTA CITY PROJECT NO. 238 PRELIMINARY COST ESTIMATES ALTERNATIVE NO. 1 ITEM QUANTITY UNIT PRICE AMOUNT 1. Pond Excavation 19000 C.Y. $3.00 $57,000.00 Sub -Total $57,000.00 + 10% Contingencies $5,700.00 Sub -Total $62,700.00 + 30% Administration $18,800.00 TOTAL ESTIMATED PROJECT COST $81,500.00 ALTERNATIVE NO. 2 ITEM QUANTITY UNIT PRICE AMOUNT 1. 21" RCP Storm Sewer 1700 L.F. $27.00 $45,900.00 2. 21" RCP FES 2 EACH $700.00 $1,400.00 3. CB/MH 7 EACH $1,000.00 $7,000.00 4. Jacking Across S.T.H. No. 3 60 L.F. $200.00 $12,000.00 5. Restoration 2 ACRE $1,500.00 $3,000.00 Sub -Total $69,300.00 + 10% Contingencies $6,930.00 Sub -Total $76,230.00 i+ 30% Administration $22,170.00 TOTAL ESTIMATED PROJECT COST $99,100.00 1 ALTERNATIVE NO. 3 ITEM QUANTITY UNIT PRICE AMOUNT 1. 21" RCP Storm Sewer 1700 L.F. $27.00 $45,900.00 2. 21" RCP FES 2 EACH $700.00 $1,400.00 3. CB/MH 7 EACH $1,000.00 $7,000.00 4. Jacking Across S.T.H. No. 3 60 L.F. $200.00 $12,000.00 5. Lift Station and Forcemain 1 LUMP SUM $80,000.00 $80,000.00 6. Restoration 4 ACRE $1,500.00 $6,000.00 Sub -Total Jacking Across S.T.H. No. 3 60 L.F. $152,300.00 + 10% Contingencies Lift Station and Forcemain 1 LUMP SUM $15,230.00 Sub -Total 7. Restoration $167,530.00 + 30% Administration Sub -Total $50,270.00 TOTAL ESTIMATED PROJECT COST + $217,800.00 ALTERNATIVE NO. 4 ITEM QUANTITY UNIT PRICE AMOUNT 1. Pond Excavation 19000 C.Y. $3.00 $57,000.00 1. 18" RCP Storm Sewer 1700 L.F. $23.00 $39,100.00 3. 18" RCP FES 2 EACH $500.00 $1,000.00 4. CB/MH 7 EACH $1,000.00 $7,000.00 5. Jacking Across S.T.H. No. 3 60 L.F. $200.00 $12,000.00 6. Lift Station and Forcemain 1 LUMP SUM $80,000.00 $80,000.00 7. Restoration 4 ACRE $1,500.00 $6,000.00 Sub -Total $202,100.00 + 10% Contingencies $20,210.00 Sub -Total $222,310.00 + 30% Administration $66,690.00 TOTAL ESTIMATED PROJECT COST $289,000.00 fr 100 YEAR FLOOD BOUNDARY ;CAWARZ POND I1 O 1 1. 0 I SCH ...r t NO NATIONAL GUARD / ARMORY WL=921.5 ujw t f• w W I SCH 153 I; cc _ i L°932'3 10 u. 1 1 U u. iNWL=956.0 �1 w r �HWL=962.5 ` I i R E I i RECREATION L r rin�, FIELD BERM �----.�_:-_--_----- fig• 1,RECREATION yFIELD �Ov L---------- as SCHOOL N 400 0 400 800 scale feet rl o3 Z Co r m r m m r m ALTERNATIVE NO. 1 ARMORY SITE DRAINAGE CITY OF ROSEMOUNT, MINNESOTA 8.4 AC -FT POND i V/ REATIO FIELD // ERN 177 _� 1 100 YEAR FLOOD 11-2 913HWL= 937.C/;/ - BOUNDARY /\ EX. 24 CMP Q \ \\ , N R E l.� ERICK�ON POND N ERN 190 ,y NWL= 920.8 t l\ -HWL= 934.4 100 YEAR FLOOD BOUNDARY ;CAWARZ POND 11 0 I 0 SCH 151 a o ; a o W L=921 .5, w w rr cw t f cc w_ L:93 c 2.3 + f U w I 0 w �t w w I cc I i cc t � � NATIONAL GUARD ARMORY i SCH 153 NWL=956.0 ;HWL=961.8 ALTERNATIVE NO. z ARMORY SITE DRAINAGE CITY OF z ROSEMOUNT, MINNESOTA U lL 2.4 AC—FT POND v SCHOOL N 400 0 400 800 arpla feet 21" RCP V/ r 177//) // 100 YEAR 937:C/ EtOUNDARY " CMP/ ��'CREAT►0tA � ERICKON POND f ERN 190 NWL= 920.8 rHWL= 935.9 � 1 FLOOD 1 t RE G REAT10 RECREATION c FIELD `+� FIELD(n �! BERM �------ti—=�--------- -- E R N W L= �5. [,RECREATION HWL= ti FIELD EX. 24 �%°� v SCHOOL N 400 0 400 800 arpla feet 21" RCP V/ r 177//) // 100 YEAR 937:C/ EtOUNDARY " CMP/ ��'CREAT►0tA � ERICKON POND f ERN 190 NWL= 920.8 rHWL= 935.9 � 1 FLOOD 100 YEAR FLOOD BOUNDARY NATIONAL GUARD ARMORY i SCH 153 NWL=956.0 �HWL=964.4 e I t '1 1 l� rR E j RECREATION L - r r1n, I r FIELD BERM !RECREATION FIELD �OJ� L ------___- SCHOOL N 400 0 400 800 of slo feet d Q 1 g" RCP 77"i 1 � .ERN 177 100 YEAR FLOOD NWL= 933. BOUNDARY HWL= 937. / REATIO FIELD Al TFRNATIVF N0= 4 ARMORY SITE Q.RAINAGE CITY OF ROSEMOUNT) MINNESOTA fEX. 24 CMP / Q \\ A.T1014 / I ERICKSON POND N ERN 190 NWL= 920.8 -HWL=944.6 La 1 � l 1O r za ND\ iCH�WARZ POND Ii 5151SCH fI a p WL=921. W T w w L=928.4 j � LL f U w �t U w -- r w cc i °C 1 f 18 t RCPT NATIONAL GUARD ARMORY i SCH 153 NWL=956.0 �HWL=964.4 e I t '1 1 l� rR E j RECREATION L - r r1n, I r FIELD BERM !RECREATION FIELD �OJ� L ------___- SCHOOL N 400 0 400 800 of slo feet d Q 1 g" RCP 77"i 1 � .ERN 177 100 YEAR FLOOD NWL= 933. BOUNDARY HWL= 937. / REATIO FIELD Al TFRNATIVF N0= 4 ARMORY SITE Q.RAINAGE CITY OF ROSEMOUNT) MINNESOTA fEX. 24 CMP / Q \\ A.T1014 / I ERICKSON POND N ERN 190 NWL= 920.8 -HWL=944.6 La 1 � l 100 YEAR FLOOD BOUNDARY 1 `� r Z • ; Z ;CAWARZ POND I O_ SCH WL=921.5 i a i i w w L=93 0.5, w II w i �r U w � � U w i w c , L J r cc TATIOjN FOK�EMAIN ll .� NATIONAL GUARD ARMORY SCH 153 NWL=956.0(� HWL=962.0 r_ 1l I R E RECREATION L FIELD BERM �c�• 1,RECREATION yFIELD P V SCHOOL N. 400 0 400 800 .ralA feet AL T E R N A T 1VE Ilk 1 J ARMORY SITE DRAINAGE CITY OF ROSEMOUNT, MINNESOTA 2.4 AC -FT POND C:�) 21" RCP - REATIO r—n/ FIELD �/ U ERN 177 _% i 100 YEAR WL= 933. BOUNDARY HWL= 937. EX. 24 CMP CREA SON ERICK'�ON POND ERN 190 ,2 f NWL= 920.8 t .HWL=944.6 w� J � J FLOOD 100 YEAR FLOOD BOUNDARY r� I ;CAWARZ POND 1 0 i 0 SCH 151 WL=921.5 w ' ccw t w L=930.5, I U w I U u. Ir w i I w j l cc I I cc TATIO� FOIR�EMAIN NATIONAL GUARD ARMORY i SCH 153 NWL=956.0 HWL=959.1 � - v l� IRE RECREATION L � � 1 FIELD --Jrn I BERM��----;–�--------- �c�• 1111ECREAT10N FIELD 0�� 5<,- V A' SCHOOL N 400 0 400 800 „► REAT1011 FIELD m m m m m m = ALTERNATIVE NO. 4 ARMORY SITE DRAINAGE CITY OF ROSEMOUNT, MINNESOTA co 8.4 AC—FT POND —>> 1+RCP 7/vv r_n ERN 177 _��i 100 YEAR W L = 933. \ 13OUNDARY HWL= 937. / EX. 24" CMP N CREA � / I f ERICK!�DN POND ERN 190 •''` f NWL= 920.8 -HWL=944.6 1 FLOOD