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10-21-96 WSFEASIBILITY REPORT FOR PROPOSED BITUMINOUS STREET RECONSTRUCTION OF 85TH STREET OTSEGO, MINNESOTA Prepared by: HAKANSON ANDERSON ASSOCIATES, INC. 3601 Thurston Avenue Anoka, Minnesota 55303 Telephone: (612) 427-5860 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 State of Minnesota -Statutes 32.6.02 to 326.16. ce G. KoshakV, PE Kevin P. Kielb, PE OT332.rpt //(96/ 1911 Reg. No. Date Z3z>> C h 9Ag Reg. No. Date CONTENTS PROJECT DESCRIPTION.......................................1 II STUDY AREA BOUNDARY......................................1 III ROADWAY IMPROVEMENT PROJECT .............................. 1 A Existing Conditions ....................................... 1 B Proposed Improvements...................................2 C Estimated Costs ......................................... 3 D Financing and Assessments ................................. 4 1 MSA Account......................................4 2 Assessment Policy .................................. 5 3 Projected Roadway Assessments ........................ 6 IV STORM SEWER IMPROVEMENT PROJECT ........................... 8 A B C D E F G 85th Street Storm Sewer .................................. Halls Pond Area Improvements .............................. Storm Sewer Assessments................................12 Projected Funding Balance.................................13 Special Considerations - Storm Sewer Sequencing of Improvements ..............................14 Sub -Regional and Local Improvements 8 9 ........................13 ........................ 14 1 Pond in NW/4 of SW'/+ of Section 21 .................... 14 2 Vasseur's Oak Grove Estates 3rd Addition Improvements ...... 15 3 Vasseur's Oak Grove Estates 2nd Addition East Improvements ... 16 4 Vasseur's Oak Grove Estates 2nd Addition West Improvements .. 17 5 Area west of OTSEGO Acres 1 st Addition Improvements ...... 18 6 Area west of Vasseur's Oak Grove Estates Improvements ...... 19 7 Otsego Acres and Vasseur's Oak Grove Estates Improvements ... 20 8 Vasseur's Oak Grove Estates 3rd Addition Pond Improvements 21 9 Area 5A and 5B (North Odean Avenue) Improvements ........ 22 H Assessments for Sub -Regional and Local Improvements ............ 23 1 Direct Benefit Assessment ............................ 23 2 Uniform Assessment .............. ............ ...... 24 V PROJECT SCHEDULE........................................26 CONCLUSIONS AND RECOMMENDATIONS ......................... 26 APPENDIX A Exhibit A Exhibit B Exhibit C Exhibit D Exhibit E Exhibit F Exhibit G Exhibit H Exhibit I Exhibit J Exhibit K Exhibit L Exhibit M Exhibit N Exhibit 0 Exhibit P APPENDIX B ATTACHMENTS - Project Location and Halls Watershed District Boundary - -Typical MSA Urban Street Section - Roadway Construction Benefitting Properties - Hall's Pond Watershed - 85th Street Storm Sewer and Area of Benefit - Regional Pond and Area of Benefit - Areas removed from or routed away from Hall's Pond - Sub -regional Pond in Area 3B and area of benefit - Area 3A Storm Sewer and area of benefit - Area 5H Storm Sewer and area of benefit - Area 4J Storm Sewer and area of benefit - Area 2C Storm Sewer and area of benefit - Area 4A and 4K Storm Sewer and area of benefit - Area 4C, 4D, 4E, 4F, and 4G Storm Sewer and area of benefit - Area 4B Storm Sewer and are of benefit - Area 5A and 5B Storm Sewer and area of benefit RESOLUTION ORDERING HEARING AND ADDITIONAL WORK I. OBJECTIVE The objective of this report is to determine the feasibility of upgrading 85th Street from Page Avenue to Nashua Avenue to Municipal State Aid (MSA) Standards. This study will also analyze the feasibility of constructing storm sewer improvements for areas tributary to the 85th Street storm, sewer system. This study will analyze existing conditions, required improvements, funding sources, and assessment policies. The study area boundary is depicted on Exhibit A. II. PROJECT LOCATION The roadway portion of the project is located within Sections 20, 21, and 22, Township 121 N, Range 23W, in Otsego, Minnesota. The roadway location, along with the Halls Pond Watershed District boundary, is depicted on Exhibit A at the back of this report. III. ROADWAY IMPROVEMENT PROJECT A. Existing Conditions The project consists of improving 85th Street from Page Avenue to approximately 700 feet east of Nashua Avenue. The project termini are the extents of previous MSA projects which improved 85th Street to MSA Standards. 85th Street is a 24 foot wide paved rural design street with ditch sections and culverts to provide drainage. The existing shoulders consist of 0.5' to 2' of topsoil in some areas, and are non-existent in others. Odean Avenue traverses the street, separating it into east and west segments. The West segment is located between Nashua Avenue and Odean Avenue and is designated as MSA route 217-102-015. The east segment is located between Page Avenue and Odean Avenue and designated as MSA route 217-102-020. The west segment is approximately 5,000 lineal feet. The east segment is approximately 4,025 lineal feet. Both segments of roadway have exhibited signs of pavement distress in recent years. The western segment has required patching in recent years to replace areas of severe alligator cracking. The alligator cracking is caused by structural failure of the roadway section, and may be attributable to the poor subgrade materials. 1 The soils in the project area appear to vary from fine sands, to sandy loams, to loams. Inclusions of silty clay loams were noted in the section of 85th Street between Nashua Avenue and Odean Avenue. The subgrade soils are thought to be generally unsuitable for roadway construction. Test borings must be performed during the design phase of the project to determine the exact subsoil characteristics. The National Wetland Inventory (NWI) Maps indicate that several of the low areas within the existing right-of-way are Wetland Conservation Act of 1991 (WCA) wetlands. These areas will require special attention during the project design phase. The wetland areas must be delineated and work must be performed within the guidelines of the WCA. The existing ROW is 66 feet along the length of the roadway. There are no known drainage and utility easements located adjacent to the ROW. The roadway profile exhibits sharp vertical curves, reducing site distances in some areas. Site distance is also limited at several roadway intersections along the project length due to horizontal obstructions, primarily tree growth. The average daily traffic along the roadway is expected to increase in the near future due to proposed development work. An executive style golf course is planned for the NW %4 of the SE %4 of Section 20. A residential development is in the conceptual stage for the NW %4 of the SW %4 of Section 21. Both developments, when completed, will cause an increase in traffic to 85th Street, and may burden the capacity of the roadway as it exists. B. Proposed Improvements The project involves constructing the roadway to Municipal State Aid (MSA) Standards. 85th Street is proposed to be a 44 foot wide urban design section with concrete curb and gutter. Provisions for future sidewalks would be made within a 5' wide boulevard area. Provisions would also be made to allow for grading for a future bike -path on one side of the road. The typical design section will consist of a 3%" bituminous surface over 6" of Class 5 aggregate base course. A 2' layer of clean sand will be placed below the aggregate base to provide structural support where 2 C« subgrade soils are determined to be inadequate for roadway construction. Exhibit B depicts a typical MSA -urban design section. Right-of-way purchase will be required to expand the ROW from 66' to 80'. Slope easements and temporary construction easements will be required to allow for roadway construction. The extents of the easements will be determined during the design phase of the project. Estimated Costs Costs for street construction were analyzed for each segment of the proposed 85th Street. Our cost estimates are as follows: Table 111-1 85th Street Odean Avenue to Nashua Avenue MSA Segment 217-102-015 Cost Estimate Item Common Excavation and Subgrade_ Prep Class 5 Aggregate Base Course Bituminous Surfacing Concrete Curb and Gutter Erosion Control Revegetation Signs and Markings Total Estimated Construction Cost Construction Contingency at 10% ROW Acquisition Overhead at 20% TOTAL ESTIMATED PROJECT COST K3 Estimated Cost $262,400 82,200 132,500 70,000 22,500 71,000 8.500 $649,100 64,910 44,250 43.730 $801,990 A Table III -2 85th Street Page Avenue to Odean Avenue MSA Segment 217-102-020 Cost Estimate Estimated Lt�m Cost Common Excavation and Subgrade Prep $135,000 Class 5 Aggregate Base Course 66,300 Bituminous Surfacing 106,500 Concrete Curb and Gutter 57,000 Erosion Control 16,100 Revegetation 46,900 Signs and Markings 7.500 Total Estimated Construction Cost $435,300 Construction Contingency at 10% 43,530 ROW Acquisition 35,600 Overhead at 20% 78 .060 TOTAL ESTIMATED PROJECT COST $ 601,490 Financing and Assessments MSA Account The portion of 85th Street analyzed is currently on the City of Otsego's MSA system. The MSA segment designations are 217- 102-015 (Odean Avenue to Nashua Avenue) and 217-102-020 (Page Avenue to Odean Avenue). The roadway qualifies for MSA funding for construction, ROW acquisition, and engineering services. The unencumbered balance in the MSA construction account as of September 6, 1996 was $629,191.57. An amount of $4,671.28 is encumbered pending closeout of the CSAH37 and Odean Avenue intersection realignment project (MSA projects 217-105-01 and 217-020-02). In addition, approximately $25,400 has yet to be requested from MSA for ROW acquisition for that project. The actual MSA construction funds available at this time are estimated at $603,791.57. The City receives MSA allotments annually, 25% of which are 0 designed for maintenance. The remaining 75% are for utilization for construction activities. The 1996 MSA construction allotment was $229,489. MSA allotments are determined based upon population and roadway mileage within the City. The recent dissolution of Frankfort Township- resulted in a net gain of population and roadway mileage for the City of Otsego. This could provide for an increase in the total annual MSA allotment in the City receives. For purposes of this report, however, we have conservatively assumed that the 1997 allotment will be similar to the 1996 allotment. MSA allows City's advancements on funds for construction. The lesser of three years allotment or $500,000 can be advanced to Municipalities for construction projects. The maximum the City of Otsego could advance is $500,000. This is approximately 2%2 years of construction funds. As a result of this advance, the City would not receive the construction allotment in 1998 and 1999. The year 2000 construction allotment would be approximately $100,000. The advance in funds would not affect the maintenance allotment. The following table depicts the theoretical maximum MSA funding available for this project: - Table III -3 City of Otsego Estimated MSA Construction Funds Present unencumbered amount $629,191.00 Yet to be requested for CSAH37 ROW < 25,400.00> Theoretical 1997 apportionment ap33(P Potential advancement of funds 500,000.00 Total Theoretical MSA Construction Funds Available $.3 9 2. Assessment Policy The City of Otsego's Assessment Ordinance sets guidelines for determining assessment amounts for properties which abut MSA designated and eligible streets. The ordinance indicates that abutting properties shall be assessed for the costs of a typical street and any additional costs shall be paid for by the City. Because the roadway is located within the Urban Service Area, the typical roadway section would consist of a 34 foot wide 5 3 roadway with bituminous berms and 5' wide boulevards. Our estimated lineal foot cost for this type of roadway is as follows: Table III -4 City of Otsego Estimated Construction Costs Typical Urban Roadway Section I -u Common Excavation and Subgrade Prep Class 5 Aggregate Base Course Bituminous Surfacing with Curb Erosion Control Revegetation Signs Total Estimated Construction Cost Overhead and Contingency at 25% Estimated Cost per Lineal Foot $1.90 8.50 20.50 2.35 8.75 0.90 $42.90 10.73 TOTAL ESTIMATED PROJECT COST PER LF $53.63 By dividing the total estimated project cost by two, an assessment value per front foot of property is obtained. The estimated cost per front foot of property was determined to be $26.82. Projected Roadway Assessments _ Potential roadway assessments were determined based upon property access to 85th Street. Table III -5 was generated based upon half -section maps and costs described in section III -D-2. Where front footage could not be obtained from half -section maps, the distances were estimated based on aerial topography maps. The benefitting properties for the roadway construction portion of the project are depicted on Exhibit C. Based upon a front foot cost of $26.82, and a total assessable front footage of 12,597.92, the total potential revenue from street assessments was determined to be $337,876.21. 101 TABLE III -5 City of Otsego 85th Street Improvement Project Estimated Roadway Assessments Cost' LQ t Block Subdivision Front Cost Total Per Footage Per FF Cost 1�� 1 1 James Addition 160.00 $26.82 $4,291 $639 2 1 James Addition 160.00 26.82 4,291 639 3 1 James Addition 160.00 26.82 4,291 639 4 1 James Addition 160.00 26.82 4,291 639 5 1 James Addition 160.00 26.82 4,291 639 6 1 James Addition 160.00 26.82 4,291 639 7 1 James Addition 155.00 26.82 4,157 620- A of NW A Section 22 1,340.00 26.82 35,939 5356 5 3 Hall's Addition 200.00 26.82 5,364 799 6 3 Hall's Addition 200.00 26.82 5,364 799 Y4 of NE Y4 Section 21 1,300.00 26.82 34,866 5196 10 1 Vasseur's Oak Grove Estates 267.00 26.82 7,161 1067 2 1 Vasseur's Oak Grove Estates 250.00 26.82 6,705 999 3 1 Vasseur's Oak Grove Estates 250.00 26.82 6,705 999 4 1 Vasseur's Oak Grove Estates 250.00 26.82 6,705 999 5 1 Vasseur's Oak Grove Estates 250.00 26.82 6,705 999 3 1 Vasseur's Oak Grove Estates 250.00 26.82 6,705 999 7 1 Vasseur's Oak Grove Estates 218.40 26.82 5,857 873 8 1 Vasseur's Oak Grove Estates 217.00 26.82 5,820 867 1 4 Vasseur's Oak Grove Estates 367.00 26.82 9,843 1467 28 2 Vasseur's Oak Grove Estates 1 st Add 300.00 26.82 8,046 1 199 10 1 Vasseur's Oak Grove Estates 2nd Add 258.52 26.82 6,934 1033 E A of SW Y4 Section 21 660.00 26.82 17,701 2638 Y4 of SW Y4 Section 21 2,010.00 26.82 53,908 8034 3726 85th St Section 20 300.00 26.82 8,046 1 199 3776 85th St Section 20 300.00 26.82 8,046 1 199 3830 85th St Section 20 300.00 26.82 8,046 1 199 3882 85th St Section 20 300.00 26.82 8,046 1 199 3922 85th St Section 20 270.00 26.82 7,241 1079 3984 85th St Section 20 275.00 26.82 7,376 1099 Y4 of SE Y4 Section 20 1,150.00 26.82 30,843 4597 Total Estimated Amount from Roadway Assessments Based on equal annual payments for 10 years at an interest rate of 8%. $337,876 N IV. STORM SEWER IMPROVEMENT PROJECT The proposed roadway improvements will occur primarily in the Hall's Pond Watershed area. The long range watershed improvements must be considered for the design of the 85th Street improvements. The 85th Street storm sewer will serve as a trunk facility to convey stormwater from the Hall's Watershed to the Hall's Pond area. Additional improvements to the Hall's Pond Watershed are required to correct local drainage problems. Subarea descriptions utilized in this report represent the same areas as detailed in the Storm Water Drainage Report prepared in 1995 for this area. Exhibit D depicts the Hall's Pond Watershed and associated subareas. Exhibit D also depicts the physical and proposed political boundaries of the watershed. A brief analysis of the recommended storm sewer system improvements are as follows: A. 85th Street Storm Sewer The storm sewer system in 85th Street will be sized as a trunk storm sewer facility. A storm drainage system must be constructed to carry the stormwater from the proposed urban design street section. Oversizing of the storm sewer is recommended to account for future local improvements within the Hall's Pond Watershed. A preliminary storm sewer design was completed based upon data included in a Stormwater Drainage Report prepared in 1995 for the Hall's Pond Watershed. The construction costs for the storm sewer was estimated at $98,527 for the area between Page Avenue and Odean Avenue and $138,050 for the area between Odean Avenue and Nashua Avenue. The 85th Street storm sewer and area of benefit are depicted on Exhibit E. Estimated project costs for the storm sewer are listed below: Table IV -1 City of Otsego 85th Street Storm Sewer Estimated Costs Estimated Construction Cost Construction Cont. @ 10% Overhead @ 20% Total Estimate Project Cost : Page to Odean to Odean Nasha Total $98,527 $138,050 $236,577 9,853 13,805 23,658 19,705 27,61047.315 $128,085 $179,465 $307,550 B. Hall's Pond Area Improvements Construction of the 85th Street storm sewer will increase the rate and volume of water entering the Hall's Pond area. Hall's Pond is presently at or near full capacity, meaning improvements would have to be made to the pond area to allow for the extra stormwater. The low water level of Hall's Pond is set by the Department of Natural Resources (DNR) to insure that a minimum surface area of the pond is maintained. The high water elevation is governed by the low floor elevations of surrounding residences to insure flooding does not occur. The difference in these elevations is presently 1.5 feet. This is the allowable "bounce" in the pond. This bounce is very small and causes a significant hinderance to routing additional stormwater to the pond. The existing outlet from the pond is a 24" RCP pipe, 7,586 feet in length, and at a slope of 0.12%. The pipe discharges to the Mississippi River at a point north of the Mississippi Shores Addition. The present capacity of the pipe is approximately 8.5 cfs at maximum allowable pond elevation. Several options were analyzed to allow for added stormwater to the Hall's Pond area. These options are described below: 1 . Construct a regional pond in the SW %4 of the '/4 of Section 21 This alternative allows for full development of the Hall's Pond Watershed with restrictions as described ins Section IV -E of this report. The excavation work would be performed in conjunction with the 85th Street roadway project. A portion of the material excavated would be utilized as clean fill for the 85th Street roadways, and the remaining material would be hauled off-site or graded into the pond easement area. Approximately 110,000 cubic yards of material would be excavated. The project would also include site grading, topsoil import, re -vegetation, and landscaping. Our estimated costs for this project are as follows: 41 2. 3. Table IV -2 City of Otsego Regional Pond Cost Estimate Construction Easement Acquisition Construction Contingency @ 10% Overhead @ 20% Total Project Cost $175,000 32,500 17,500 35.000 $260,000 The costs shown consider simultaneous roadway construction and pond construction. Pond construction costs will increase if the pond is constructed as a separate project. Purchase Surrounding Residences This alterative would allow for increasing the high water level of Hall's Pond to provide increased storage volume in the pond. Our preliminary analysis indicates that approximately 10 residences would be affected by an increase in the high water line of Hall's Pond. The City would be required to purchase these properties and incur relocation costs of the residents. Based upon the relatively high number of residences involved, this option becomes significantly more costly than Alternative 1. We did not pursue this option further. Auxiliary Gravity Outlet System This alternative involves construction of a gravity sewer outlet pipe, parallel to the existing 24" outlet pipe, from Hall's Pond to the Mississippi River. The existing outlet pipe is 24" RCP, 7,586 feet in length, and at a slope of 0.12%. Because Hall's Pond is at full capacity, the auxiliary outlet pipe would have to be sized to convey the proposed additional inflow to the pond. The additional peak inflow is estimated at 43.9 cfs. Based upon a computer model of the drainage, a gravity outlet alone will not convey the additional stormwater without increasing the pond elevation. We have estimated the cost for a 48" RCP pipe for discussion purposes only. 10 0 5. Table IV -3 City of Otsego Auxiliary Gravity Outlet for Hall's Pond Cost Estimate Construction Construction Contingency @ 10% Overhead @ 20% Total Project Cost Lift Station with Forcemain $769,472 76,947 153.894 $1,000,313 A lift station with a forcemain could be utilized to pump the additional inflow from Hall's Pond to the Mississippi River. The lift station would be designed to pump the additional peak inflow to Hall's Pond. The forcemain would also be sized to handle the additional peak inflow flow. A 36" diameter forcemain would be required to convey the 20,000 gpm peak flow. The lift station would require four primary and one backup pump to provide adequate capacity to handle the additional peak flow. We have estimated the cost of this alternative as follows: Table IV -4 City of Otsego Hall's Pond Lift Station Estimated Costs Lift Station Structure with Pumps & Controls Forcemain with Outlet Structure Construction Construction Contingency @ 10% Overhead @ 20% Total Estimated Project Cost Review of Alternatives $ 200,000 845,000 - 1,045,000 104,500 209.000 $1,358,500 Based upon our review of the alternatives, pond excavation appears to be the most cost-effective means of expanding the storage capacity of the Hall's Pond area. Non -quantifiable 11 C implications, such as creation of a scenic park area and recreational benefits also make this a desirable alternative. The pond size, location, and area of benefit are depicted on Exhibit F. 6. MSA Participation for Stormwater Improvements The MSA participation for storm sewer improvements is based upon the percentage of area contributing to a storm sewer system vs. the ROW area contributing to the storm sewer system. MSA participates up to a maximum of 100%, and to a minimum of 55%. Because of the size of Hall's Pond Watershed in relation to the ROW, the minimum of 55%will be utilized for this project. Storm Sewer Assessment The City's assessment ordnance indicates that the cost for construction of storm sewers shall be assessed against the property in the area serviced by the sewer on the basis of equivalent square footage of the property. For the trunk facilities in 85th Street, and for the regional pond expansion, all properties who have the potential to access these facilities would be considered to be served by them. We have estimated that the area of benefit for the proposed trunk facilities is approximately 468.6 acres of land. This does not include existing or proposed ponding or easement areas. This also does not include City ROW areas for roads. Based on an MSA contribution of 55% of the trunk facility costs, a breakdown of costs was determined as follows: Table IV -5 City of Otsego Trunk Storm Sewer Facilities Hall's Pond Watershed Cost Estimate Item 85th Street Trunk Facility Regional Pond Expansion Required MSA Assessment $169,153 $138,397 143.000 117000 W*M. Total $312,153 $255,397 $567,550 Based upon an assessment amount of $255,397 and an assessment acreage of 468.6, an assessment per acre of property was determined 12 a E at $ 545.02. This equates to a cost per square foot of property of $0.013/SF. Projected Funding Balance Based upon our initial review of the project, we have prepared the following table: Table IV -6 City of Otsego 85th Street Project Projected Funding Balance Special Considerations - Storm Sewer The extra capacity provided by the proposed regional pond alone will not allow for the entire Hall's Pond Watershed District to be directly routed to the Hall's Pond area. We recommend several conditions or changes be made to the watershed to allow for construction of a functional system: 1 . Area 51 (NW Y4 of the SW'/4, Section 22) be diverted to the Lefebvre Watershed at the time this land is developed. -- 2. Areas 5G, 6A, 6B, 6C, and 6D continue to drain away from Hall's Pond for stormwater ponding. 3. A sub -regional pond be developed in area 3B (NW'/4 of the SWY4, Section 21) to detain all stormwater from areas 3A, 3B, 3C, 3D, and 3E. The pond will have an outlet to the 85th Street stormwater system, but the outflow will be at a reduced rate. 4. All presently undeveloped lands must pond the entire 100 year storm, and release at a reduced rate. We recommend reducing 13 Total MSA Assessment Item Cost Cost cost 85th Street Construction $1,403,480 $1,065,614 $337,866 85th Street Storm Sewer 307,550 169,153 138,397 Regional Pond Expansion 260.000 143.000 117,000 Project Totals $1,971,030 $1,377,767 $ 593,263 Special Considerations - Storm Sewer The extra capacity provided by the proposed regional pond alone will not allow for the entire Hall's Pond Watershed District to be directly routed to the Hall's Pond area. We recommend several conditions or changes be made to the watershed to allow for construction of a functional system: 1 . Area 51 (NW Y4 of the SW'/4, Section 22) be diverted to the Lefebvre Watershed at the time this land is developed. -- 2. Areas 5G, 6A, 6B, 6C, and 6D continue to drain away from Hall's Pond for stormwater ponding. 3. A sub -regional pond be developed in area 3B (NW'/4 of the SWY4, Section 21) to detain all stormwater from areas 3A, 3B, 3C, 3D, and 3E. The pond will have an outlet to the 85th Street stormwater system, but the outflow will be at a reduced rate. 4. All presently undeveloped lands must pond the entire 100 year storm, and release at a reduced rate. We recommend reducing 13 the outflow rate to twice the average annual rainfall amount, released over a six month period. This will ensure that the localized ponds do not flood and will lessen the impacts to the downstream storm sewer system. By implementing the above strategies, the proposed improvements to the Hall's Pond Watershed should provide a long term solution to the drainage problems in the area. Exhibit G depicts the proposed restrictions listed in Items 1 and 2 above. F. Sequencing of Improvements This report describes many improvements to the Hall's Pond Watershed area. The improvements vary from local, to sub -regional to regional in nature. Although there is no specific sequential order in which many of the improvements can be made, there is a general order which must be followed. Downstream improvements must be made prior to upstream improvements occurring. This will insure that downstream areas are not flooded due to the upstream improvements. A description of a portion of the required sequencing follows: 1 . The 85th Street Storm Sewer and regional pond expansion must be constructed prior to localized or sub -regional improvements. 2. The pond in area 3B must be constructed prior to any of the localized area 3A, 3B, 3C, 3D, and 3E improvements. 3. Any localized improvements which will utilize downstream facilities cannot be constructed until the downstream facilities are in place. These restrictions may limit development of land within the Hall's Pond Watershed. G. Sub -Regional and Localized Improvements 1 . Pond in the NW Y4 of the SW Y4, Section 21 This pond is located in Subarea 3B of the Stormwater Drainage Report. The pond will be created around an existing wetland area and will serve to provide stormwater control for Subareas 3A, 3B, 3C, 3D, and 3E. The pond will be created to provide stormwater retention of the entire 100 year storm runoff, and will release at 14 a rate of two times the average annual precipitation rate over a six month period. We have estimated the cost of this improvement as follows: Table IV -6 City of Otsego Sub -Regional Pond Construction Hall's Pond Watershed District 3B Cost Estimate Estimated Item Cost Construction $249,700 Easement Acquisition 50,000 Overhead and Contingency @ 25% 62.425 Total Project Cost $362,125 The area of benefit for this project would include areas 3A, 3B, 3C, 3D, and 3E. We have estimated the total area of benefit, less roadways ponds and easements, to be 196.87 acres. This yields a cost of $1,839.41 per acre, or a cost of $0.0422 per square foot. Pond location, easement area, and area of benefit are depicted on Exhibit H. Based on an interest rate of 8% and a 10 year payoff period, an annual cost of $274.13 per acre would be incurred. 2. Vasseur's Oak Grove Estates 3rd Addition Improvements This is area 3A of the Stormwater Drainage Report. The 85th Street storm sewer improvements, the regional pond improvements and the sub -regional pond improvements in area 3B would have to be constructed prior to this improvement being implemented. The recommended improvements consist of constructing a drainage ditch west of and south of the existing platted lands to prevent direct off-site runoff from entering the platted properties. Localized ponds would be created south of and west of the platted lands to aid in buffering this stormwater flow. A stormwater collection pond would be created within the platted lands to collect stormwater to be discharged to the sub -regional 15 0 pond in area 36. Storm sewer pipe would be utilized to connect the local ponds and also to connect the collection pond to the sub -regional pond. Improvements to the existing ditch system would also be required to direct flows from the platted lands to the collection pond. We have estimated the cost of these improvements as follows: Table IV -7 City of Otsego Area 3A Drainage Improvements Cost Estimate Estimated Item Cost Construction $143,230 Easements 20,000 Overhead and Contingencies @ 25% 35.808 Total Project Cost $199,038 These improvements would benefit areas 3A and 3C. We have estimated the total area of benefit, less roadways, ponds, and easements to be 60.47 acres. This yields a cost of $3,291.52 per acre or $0.0756 per square foot. Pond locations, pipe size and locations, easement areas, and area of benefit are depicted on Exhibit I. Based on equal annual payments, an interest rate of 8%, and a 10 year payoff period, an annual cost of $490.54 per acre would be incurred. Vasseur's Oak Grove Estates 2nd Addition East Improvements This is area 5H of the Stormwater Drainage Report. The regional pond expansion and the 85th Street Storm Sewer would have to be constructed prior to installation of this system. The recommended improvements consist of construction of a stormwater collection pond between Ogren Avenue and Packard Avenue. Storm Sewer pipe would convey water from this pond to the 85th Street system, and ultimately to the regional pond. Localized ditch grading and storm sewer pipe would be required to convey water to the collection pond. We have estimated the costs of these improvements as follows: U101 EN Table IV -8 City of Otsego Area 5H Drainage Improvements Cost Estimate Estimated km Cost Construction $49,500 Easements 10,000 Overhead and Contingencies @ 25% 12,375 Total Project Cost $71,875 The area of benefit would be limited to area 5H of the Stormwater Drainage Report. The estimated acreage of this sub- district, less roadways, ponds, and easements, is 32.54 acres. This yields a cost of $2,208.82 per acre or $0.051 per square foot. Pond locations, pipe sizes and locations, easement areas, and area of benefit are depicted on Exhibit J. Based on equal annual payments, an interest rate of 8%, and a 10 year payoff period, an annual cost of $329.18 per acre would be incurred. Vasseur's Oak Grove Estates 2nd Addition West Improvements This is area 4J of the Stormwater Drainage Report. The Regional Pond expansion and the 85th Street Storm Sewer system would have to be constructed prior to implementation of this system. This system would require utilization and protection of existing ponding areas within the subarea. An outlet pipe would be constructed from these ponding areas to the 85th Street storm sewer system and ultimately to the regional pond. Localized ditch grading would occur to direct flows to the local ponds and to the proposed storm sewer. We have estimated the costs of these improvements as follows: 17 5 Table IV -9 City of Otsego Area 4J Drainage Improvements Cost Estimate Estimated ltem Cost Construction $53,585 Easements 5,500 Overhead and Contingency @ 25% 13.396 Total Project Cost $ 72,481 The area of benefit would be limited to area 4J of the Stormwater Drainage Report. The estimated acreage of this sub -district, less roadways, ponds, and easements, is 31.55 acres. This yields a cost of $2,297.34 per acre and a cost of $0.053 per square foot. Pond locations, pipe sizes and locations, easement areas, and area of benefit are depicted on Exhibit K. Based on equal annual payments, an interest rate of 8%, and a 10 year payoff period, an annual cost of $342.37 per acre would be incurred. Area West of Otsego Acres 1 st Addition Improvements This is area 2C of the Stormwater Drainage Report. Improvements to areas 4D, 4F and 4G, as well as the 85th Street trunk system and the regional pond expansion would have to be completed prior to these improvements occurring. This area would also require complete ponding of the 100 year storm event for undeveloped portions of the subareas. This system would include construction of a stormwater retention pond and construction of an outlet from the pond. The outlet would discharge into Subarea 4D, and be conveyed to 85th Street and eventually to the regional pond. We have estimated the costs of these improvements as follows: C Table 1V-10 City of Otsego Area 2C Drainage Improvements Cost Estimate Estimated Item Cost Construction $55,860 Easements 10,000 Overhead and Contingency @ 25% 13.965 Total Project Cost $ 79,825 The area of benefit would be limited to area 2C of the Stormwater Drainage Report. The estimated acreage of this subarea, less roadways, ponds, and easements, is 35.69 acres. This yields a cost of $2,236.62 per acre or a cost of $0.0513 per square foot. Pond locations, pipe size and location, easement areas, and area of benefit are depicted on Exhibit L. Based on equal annual payments, an interest rate of 8% and a 10 year payoff period, an annual payment of $333.32 per acre would be required. Area West of Vasseur's Oak Grove Estates Improvements This is area 4A of the Stormwater Drainage Report and also contains improvements to area 4K of the same report. The improvements to area 4F and 4G, as well as the 85th Street system and regional pond would have to be constructed prior to this system being installed. The improvements would consist of constructing a localized pond and protecting several other small ponding areas within the subdistricts. An outlet from the ponds would be constructed to discharge into Subarea 4F and eventually into the 85th Street storm sewer system and to the regional pond. We have estimated the cost of this system as follows: 19 7 Table IV -11 City of Otsego Area 4A and 4K Drainage Improvements Cost Estimate Estimated Item Cost Construction $47,220 Easements 10,000 Overhead and Contingency @ 25% 11,805 Total Project Cost $69,025 The area of benefit would be limited to area 4A and 4K of the Stormwater Drainage Report. The estimated acreage of these subareas, less roadways, ponds, and easements, is 32.72 acres. This yields a cost of $2,109.57 per acre and a cost of $0.0484 per square foot. Pond locations, pipe size and location, easement area, and area of benefit are depicted on Exhibit M. Based on equal annual payments, an interest rate of 8%, and a 10 year payoff period, an annual payment of $314.39 per acre would be required. Otsego Acres and Vasseur's Oak Grove Estates Improvements This is area 4C, 4D, 4E, 4F, and 4G of the Stormwater Drainage Report. This system will also serve to carry stormwater from areas 2C and 4A to the 85th Street Storm Sewer system and ultimately to the regional pond. The improvements to the 85th Street system and construction of the regional pond will be required prior to construction of this local system. The improvements will require protection and cleaning of existing drainage swales and ponding areas. Several stormwater collection ponds will be created to channel stormwater to a pipe system. The pipe system will carry stormwater from the collection ponds to 85th Street system and eventually to the regional pond. Inflow from areas 2C and 4A will be accounted for in the pipe system. We have estimated that the cost of this system will be as follows: 20 Table IV -12 City of Otsego Area 4C, 4D, 4E and 4G Drainage Improvements Cost Estimate Estimated Item Cost Construction $135,250 Easements 12,500 Overhead and Contingency @ 25% 33,813 Total Project Cost $181,563 The area of benefit would include areas 2C, 4A, 4C, 4D, 4E, 4F, and 4G. The combined estimated acreage of these subareas, less roadways, ponds, and easements, is 157.08 acres. This yields a cost of $1,155.86 per acre or $0.0265 per square foot. Pond location, pipe size and location, easement areas, and area of benefit are depicted on Exhibit N. Based on equal annual payments, an interest rate of 8%, and a 10 year payoff period, an annual payment of $172.26 per acre would be required. Vasseur's Oak Grove Estates 3rd Addition Pond Improvements This is area 4B of the Stormwater Drainage Report. This system will outlet to the 85th Street system and will ultimately discharge to the regional pond. The 85th Street system and the regional pond will have to be constructed prior to this system being implemented. This system will consist of constructing a local pond system and related ditch work to convey water to the pond. We have estimated the cost of constructing this system as follows: 21 9 Table IV -13 City of Otsego Area 4B Drainage Improvements Cost Estimate Estimated AIM Cost Construction $16,500 Easements 5,000 Overhead and Contingency @ 25% 4,125 Total Project Cost $25,625 The area of benefit would be area 4B as shown in the Stormwater Drainage Report. The estimated area of Subdistrict 4B, less roadways, ponds, and easements, is 19.64 acres. This yields a cost of $1,304.74 per acre or $0.030 per square foot. Pond locations, pipe size and location, easement area, and area of benefit are depicted on Exhibit 0. Based on equal annual payments, an interest rate of 8%, and a 10 year payoff period, an annual amount of $194.45 per acre would be incurred. Area 5A and 5B (North Odean Avenue) Improvements Areas 5A and 5B of the Stormwater Drainage Report are located adjacent to Odean Avenue, North of 85th Street. The system will discharge into Hall's Pond and is an improvement to the existing drainage system. The regional pond expansion should occur prior to this improvement to insure adequate storage is available at the Hall's Pond site. This system will consist of protecting and improving existing ponding areas and constructing a pipe system from the local ponds to the regional pond. The existing ditch system will be improved to carry stormwater runoff to the localized ponding areas. We have estimated the cost of this improvement as follows: 22 W Table IV -14 City of Otsego Area 5A and 56 Drainage Improvements Cost Estimate Estimated Item Cost Construction $39,385 Easements 6,500 Overhead and Contingency @ 25% 9.846 Total Project Cost $55,731 The area of benefit would be areas 5A and 5B of the Stormwater Drainage Report. The total estimated area of 5A and 5B, less roadways, ponds, and easements, is 28.71 acres. This yields a cost of $1,941.17 per acre or $0.045 per square foot. Pond location, pipe size and location, easement areas, and area of benefit are depicted on Exhibit P. Based on equal annual payments, an interest rate of 8% and a 10 year payoff period, an annual amount of $289.29 per acre would be incurred. Assessments for Sub -Regional and Local Improvements The improvements described in Section G provide benefit to local and sub -regional areas. We have analyzed two methods of assessments for these improvements. These alternatives for assessments are as described below: 1 . Direct Benefit Assessment This method would apply assessments directly against the areas which benefit from improvements. These are the areas described under each improvement detailed in Section G. This leads to an uneven assessment throughout the watershed. Areas farthest away from Hall's Pond would be assessed for all improvements between their properties and the regional pond. An analysis for local and sub -regional improvements is provided in Table IV -15. The areas shown correspond to the areas listed in the Stormwater Drainage Report. The assessment amount varies from $545 to $5,676, depending upon the distance from the regional pond. 23 2. Uniform Assessment This alternative would utilize a uniform assessment rate for all improvements to areas tributary to the proposal regional pond. Areas 5A and 5B do not flow to the proposed regional pond and are not included in this analysis. The total estimated cost of the remainder of the improvements are depicted in Table IV -16. Based upon an estimated area of 468.6 acres, a uniform assessment of $2,810.40 per acre or $0.065 per square foot would be required to pay for the storm sewer improvements for areas tributary to the proposed regional pond. Based upon a uniform annual payment, an interest rate of 8% and a 10 year payoff period, an annual payment of $418.83 per acre would be incurred. This includes all local improvements as well as costs for the 85th Street Storm Sewer and regional pond. The regional pond and 85th Street Storm Sewer will require an estimated $545.03 assessment per acre. Based on equal annual payments, an interest rate of 8% and a 10 year payoff period, an annual payment $81.23 per acre would be incurred. Table IV -16 City of Otsego Assessment Alternative #2 Uniform Assessment Estimated Improvement Cost Regional Pond $117,000 85th Street Storm Sewer 138,397 Pond in NW %4 of the SW'/4 of Section 21 362,125 Vasseur's Oak Grove Estates 3rd Addition 199,038 Vasseur's Oak Grove Estates 2nd Addition East 71,875 Vasseur's Oak Grove Estates 2nd Addition West 72,481 Area West of Otsego Acres 1 st Addition 79,825 Area West of Vasseur's Oak Grove Estates 69,026 Otsego Acres and Vasseur's Oak Grove Estates 1 81 ,563 Vasseur's Oak Grove Estates 3rd Addition Pond 25.625 Total $1,316,954 24 Table IV -15 City of Otsego Assessment Alternative #2 Direct Benefit Assessment 25 Sub- Otsego Reg. Trunk Regional Acres & Vasseur's Pond Storm Pond Vasseur's Vasseur's Vasseur's Area W Area W of Vasseur's Oak Grove Near Sewer located Oak Grove Oak Grove Oak Grove of Otsego Vasseur's Oak Grove Estates Areas Total Hall's Facility in Sub- Estates Estates Estates Acres 1 st Oak Grove North 3rd Add 5A & 5B per Subarea Pond 85th St Dist 3B 3rd Add 2nd Add E 2nd Add W Addition Estates Pond Ave N Odean Subarea 2C ... $249.68. $295.35 ......................................... $2,236.62 ........... $1,155.86 .................. ...... $3,937.51 3A ... $249.68. $295.35 $1,839.41 $3,291.52 3B ...$249.68. $295.35 ....................................................... .............. $1,839.41 $5,675.96 3C ... $249.68. $295.35 ..................................................................... • .. • . • . • $1,839.41 $3,291.52....................................................... $2,384.44 3D...$249.68 $295.35 ..................... $1,839.41..................................................................................... $5,675.96 3E ...$249.68. $295.35 $1,839.41......................................................... $2,384.44 4A $249.68. $295.35 ......................... $2,384.44 ... ................................................... $2,109.57 . $1,155.86 ... ............. $3,810.46 4B ...$249.68. $295.35 ......................................................................$1,304.74............. $1,849.77 4C ... 4D $249.68. $295.35 $295.35 ............................................................. $1,155.86 ....... ................. $1,700.89 ...$249.68. 4E $295.35 ............................................................. $1,155.86 ........................ $1,700.89 ...$249.68. 4F $295.35 ............................................................. $1,155.86 ........................ $1,700.89 ...$249.68. 4G...$249.68. $295.35 ............................................................. $1,155.86 ........................ $1,700.89 4H...$249.68. $295.35 ............................................................. $1,155.86 ........................ $1,700.89 41 ...$249.68. $295.35 ............................................................. ......................... ................................. $545.03 4J...$249.68. $295.35 ....................................................... $545.03 4K $295.35 ................................ $2,297.34 ..................................................... $2,842.37 ...$249.68. 5A.................................................................................. ................................................... $2,109.57......................... $2,654.60 5B ................ ............. $1,941.17. $1,941.17 5H $295.35 ................................................................$1,941.17. $1,941.17 ...$249.68. .................... $2,208.82................................................................ $2,753.85 25 V ul PROJECT SCHEDULE The following schedule would allow for project construction to begin in 1997 and be completed in 1998: Event Date Accept Feasibility Study & Order Survey Work September 23, 1996 Hold Public Hearing November 12, 1996 Order Plans and Specifications November 25, 1996 Accept Plans and Order Bids April, 1997 Accept Bids and Award Contract May, 1997 Begin Construction June, 1997 Suspend Construction November, 1997 Resume Construction May, 1998 End Construction August, 1998 Hold Assessment Hearing October, 1998 CONCLUSIONS AND RECOMMENDATIONS This report analyzed the feasibility of reconstructing 85th Street from Page Avenue to Nashua Avenue to meet Municipal State Aid (MSA) Standards. Stormwater drainage within the Hall's Pond watershed was also reviewed. The 85th Street storm sewer will serve as a trunk facility for that watershed. The improvement is technically feasible as described in this report. Reconstruction of 85th Street is necessary due to the recent structural deterioration of the existing pavement section. Potential development in the area may tax the capacity of the existing roadway, which makes the improvement desirable. The project would be funded by assessments and by MSA funding. The project appears to be cost-effective if an advancement of MSA construction funds is obtained by the City. The estimated MSA funds available are slightly less than estimate construction contribution required of the MSA account. The MSA funds available were estimated conservatively, and may exceed the amount listed. We recommend that this study be forwarded to an appraiser for review of the assessment amounts recommended in this report. The appraiser should determine if the proposed assessment amounts are equivalent to or less than the benefit of the improvement. The storm sewer system improvements to be made in conjunction with this project include oversizing the 85th Street storm sewer to serve as a trunk facility and construction of a regional pond to allow for added capacity to the 26 Hall's Pond area. Both storm sewer improvements would be best made in conjunction with the 85th Street reconstruction project. Improvements to sub -regional and local storm sewer improvements within the Hall's Pond Watershed were reviewed. Methods of assessments for these improvements were discussed. The City should determine a fair and equitable assessment policy for these improvements. 4 27 ATTACHMENTS APPENDIX A / z V M N Q No==ao 3NI-I XiJ]dOdd / O v v cu N a'0 N W C/') � m 2to w o r � N X W n N � cn Co o N t5 r r� c W - L W 0 Q a- d �t t- W W W 0 in Of 4�i O � a- Q 0 Of N W LLJF-- Q W o Z zo Q m < o o W CDo Fn p CD Q LLf LLI J - Z ¢ CD W � � (� 1 - N Ln m �/ U) i- O m Q [if Z N U Q � J JT flo Z < Q U N — N J Lr) _ - W � F- W � Q Z U Ln N pp M (DD ]NIS J,1�JldO�Jd 1 mU ,,...�:..,�..r,-. a wJ i `- AREA OF BENEFIT EXHIBIT H SUB -REGIONAL POND IN AREA 313 AND AREA OF BENEFIT 800 0 800 1600 SCALE IN FEET Hakanson Anderson Assoc.,inc. Engineers, Surveyors L Landscape Architects 3601 Thurston Ave. Anoka, Minnesota 55303 612-427-5860 FAX 612-427-0520 0 �4 via 8 v ' aU '( 0 '00P ww CONSTRUCT DRAINAGE SWALE AND OBTA EASEMENT OVER E SAME o a,o cS P OBTAIN EMENT� r 2� • 1 AND CO UCT COLLECTION,, O °a s 5G a POND D PROTECT �n 70 'S� '' 2 a EXISTING Cr J d AIN LOW AREA wdo. Lj D NADEO/J_y (•�^^ ' z 3 [LOW 160 _4• LFDEVELOPER • TO IMPROVETLOUET ToSWALEPROTECT AND CLEAR EXISTI LOW AREAS NG ROTECT PROTECT EXISTING AREA EXISTING r 1 (I 14N' ;f LOW AREAS[ I .01 AREA OF BENEFIT EXHIBIT I AREA 3A STORM SEWER AND AREA OF BENEFIT I Hakanson Anderson 800 0 800 1600 Assoc.,Inc. Engineers, Surveyors L Landscape ArcNtects 3601 Thurston Ave. Anoka, Mnnesota 55303 SCALE IN FEET 612-427-5860 FAX 612-427-0520 600 0 600 1200 SCALE IN FEET EXHIBIT J AREA 5H STORM SEWER AND AREA OF BENEFIT Hakanson Anderson Assoc.,Inc. Engineers, Surveyors t Landscape Architects 3601 Thurston Ave, Anoka, Minnesota 55303 612-427-5860 FAX 612-427-0520 600 0 600 1200 SCALE IN FEET EXHIBIT K AREA 4J STORM SEWER AND AREA OF BENEFIT Hakanson Anderson Assoc.,inc. Engineers, Surveyors L Landscape Architects 3601 Thurston Ave. Anoka, Minnesota 55303 612-427-5860 FAX 612-427-0520 Y111%Lr1 vl UL1141_I NI 600 0 600 1200 SCALE IN FEET AREA 2C STORM SEWER AND AREA OF BENEFIT Hakanson 1"111 Anderson Assoc.,Inc. Engineers, Surveyors L Landscape Architects 3601 Thurston Ave. Anoka, Mftesota 55303 612-427-5860 FAX 612-427-0520 r11 \ l_P1 lJ i LJ L I `I L— I I I 600 0 600 1200 SCALE IN FEET EXHIBIT M AREA 4A AND 4K STORM SEWER AND AREA OF BENEFIT Hakanson Anderson Assoc.,Inc. Engineers, Surveyors L Landscape Architects 3601 Thurston Ave. Anoka, Minnesota 55303 612-427-5860 FAX 612-427-0520 600 0 600 1200 SCALE IN FEET EXHIBIT N AREA 4C, 4D, 4E, 4F, AND 4G STORM SEWER AND AREA OF BENEFIT Hakanson Anderson Assoc.,inc. Engineers, Surveyors 6 Landscape Architects 3601 Thurston Ave, Anoka, Minnesota 55303 612-427-5860 FAX 612-427-0520 4R EA 800 0 800 1600 SCALE IN FEET NEFIT EXHIBIT 0 AREA 4B STORM SEWER AND AREA OF BENEFIT Hakanson Anderson Assoc.,Inc. Engineers, Surveyors 6 Landscape Architects 3601 Thurston Ave, Anoka, Minnesota 55303 612-427-5860 FAX 612-427-0520 i l � l 800 0 800 1600 SCALE IN FEET NEFIT EXHIBIT 0 AREA 4B STORM SEWER AND AREA OF BENEFIT Hakanson Anderson Assoc.,Inc. Engineers, Surveyors 6 Landscape Architects 3601 Thurston Ave, Anoka, Minnesota 55303 612-427-5860 FAX 612-427-0520 0290—/21,-219 Xdd 0989—L24-219 COESS o;osaULMW 'oryouy 'any uo}sJnyl 109E s;Da;iy»y adoxpuoj I s.ro Can.nS •sJaawBu3 .Oul"Dossd I I Ll uosaapuy uosuDJoH ilAINIB A0 dI�Jd GN`d �JIMIS MJO1S 89 GNd VS V3JV d 1181HX3 1333 NI 3-IVDS OOZI 009 0 009 APPENDIX B RESOLUTION NO. RESOLUTION ORDERING PUBLIC HEARING AND ORDERING ADDITIONAL PRELIMINARY WORK ON AN IMPROVEMENT WHEREAS, pursuant to a resolution of the council adopted April 8, 1996, a report has been prepared by Hakanson Anderson Associates, Inc. with reference to the improvement of 85th Street between Page Avenue and a point 700 feet east of Nashua Avenue, and this report was received by the Council on September 23, 1996, and, WHEREAS, the report provides information regarding whether the proposed project is necessary, cost-effective and feasible, a NOW THEREFORE, BE IT RESOLVED BY THE CITY COUNCIL OF OTSEGO, MINNESOTA: 1. The council will consider the improvement of such street in accordance with the report and the assessment of both abutting and non -abutting properties as detailed in the report for all or a portion of the cost of the improvement pursuant to Minnesota Statutes, Chapter 429 at an estimated total cost of $1 ,971 .030. 2. A public hearing shall be held on such proposed improvement on the day of , 1996, in the council chambers of the city hall at p.m. and the clerk shall give mailed and published notice of such hearing and improvement as required by law. 3. The engineer, Hakanson Anderson Associates, Inc., shall proceed with obtaining additional information related to the project to include the following: A. Obtain an appraiser to review the proposed assessments and comment as to the relative benefit to the properties. B. Perform soil test borings along the length of the roadway. C. Obtain entry rights to the area of the regional pond and perform soil test borings in this area. D. Perform field survey work necessary for preparation of plans and specifications for the proposed improvement. Adopted by the council this day of Norm. F. Freske, Mayor 1996. Elaine Beatty, Clerk