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HomeMy WebLinkAboutCity Council Packet 12-07-1987 SpecialA G E N D A CITY COUNCIL/STAFF MEETING December 7, 1987 5:00 p.m. 5:00 p.m. - Dinner 5:30 p.m. - I. I & I Study Discussion II. Legal ramifications of allowing storm water to flow into street - City Attorney III. Information regarding Amber Woods - remaining street life expectancy, storm water capacity analysis, prevalent water flow, analysis of total storm water which can be eliminated from sanitary sewer system and savings, appreciation to homesteads by mitigation of problem, and methods of assessing costs for such improvements. 7:30 p.m. - Adjourn CITY OF PLYMOUTH 3400 PLYMOUTH BLVD., PLYMOUTH, MINNESOTA 55447 TELEPHONE (612) 559-2800 MEMO DATE: December 4, 1987 TO: James G. Willis, City Manager FROM: Fred G. Moore, Director of Public Works SUBJECT: SEWER SYSTEM EVALUATION I/I ANALYSIS AMBER WOODS AREA The City Council has set a dinner meeting for 5:00 P.M. December 7 for further discussion on the sewer system evaluation which was done for the Amber Woods Area. I am attaching a summary of the report which was presented to the City Council at the November 2nd Meeting. You and Council Members should also bring your copy of the entire report to the study meeting. The following is additional information to questions raised by Council Members on November 2nd: 1. Legal ramifications. Attached is a letter from Jim Thompson, City Attorney discussing the legal ramifications of sump pumps discharging their water to the City streets. There may be some liability for the City especially if we specify how property owners shall disconnect their sump pump which is discharging to the sanitary sewer system. It is against the City and State codes to discharge a sump pump to the City Sanitary System. 2. Street Condition. The City's pavement evaluation study rated the streets in the Hughes Johnson Addition as No. 1 priority and the streets within the Amber Woods Addition as No. 16 priority relative to the 65 areas of the City in the report. All of the streets in the Hughes Johnson Addition require partial reconstruction. Within the Amber Woods Addition, approximately one-half of the streets require resurfacing, one-fourth of the streets require partial reconstruction and the remaining one-fourth of the streets require only routine maintenance. Although part of the streets are a No. 1 priority, they have deteriorated beyond the condition where only resurfacing is required. For this reason, neither area was choosen as a high priority in the program where the intent is to do work in areas where the street system can be protected from further deterioration at a minimum cost. 3. Cost Saving for reduction in flow to Waste Water Treatment Plant. Based upon the estimated flow contained within the report for a home which has a discharge to the sanitary sewer system, the estimated savings in treatment cost would be $800.00 per year. This is based upon a flow of 547,500 gallons per year, at our current rate of 1.46 per one thousand gallons. 4. Affect on property values. Currently each property owner has taken whatever steps are necessary in their opinion to protect their property value. In many instances their solution has been to connect the sump pump to the sanitary sewer system. There would be a decline in property values if by disconnecting the sump pumps, water problems were caused on the individual lots. In order to prevent this decline in property values, the solution must not transfer the problem from the sanitary sewer system to the rear yards of the properties. 5. Capacity of storm sewer system. Storm sewer systems within the City of Plymouth are designed for a rainfall event with a return frequency of once every five years. For this reason, we know the storm sewer system will be overloaded on occasions of larger event rainfalls. During these larger storms, there is water flowing or ponding within the streets for a short period of time. Since the houses, which are subject to damage, are higher than the streets this does not cause a problem. The six inch curb along the street is high enough to contain the larger rainfall events and we know of no problems of water overtopping the curb into the yard area. Since the peak discharge of the sump pumps into the storm sewer system would very unlikely occur at the same time of the peak discharge of a rainfall, it is very unlikely a problem would occur. If a problem did occur, it would only be more flow or flooding in the streets for a longer period of time. Alternate 3 and Alternate 4 contained within the study provided for additional storm sewer systems for the discharge of sump pumps. The cost estimate for these systems is approximately $600,000. This is a cost of approximately 3,000 per dwelling unit. For this reason it will be very unlikely that any assessment program with the full cost being paid for by the property owners will be accepted. I believe this City cannot continue to disregard the illegal connection of sump pumps within this area. For this reason I would recommend the following: 1. During 1988, the Engineering Division contact each homeowner that has a sump pump connected to the sanitary sewer system or the homeowners which were not contacted as part of the initial survey. That a recommendation be made to each one of these homeowners on alternate discharges for their sump pump. The existing surface drainage around the house would be reviewed in making this recommendation. Each homeowner would be required to disconnect their sump pump from the sanitary sewer system within 120 days after receiving the recommendation. 2. The City consider providing a low interest funding program to pay the cost for each property owner to remove their connection. 3. If there are property owners which have not disconnected their sump pumps that the City inact an ordinance placing a surcharge for the use of the sanitary sewer system for sump pump discharges. I believe this surcharge should reflect at least the $800.00 per year treatment cost. Sump pump discharges to the sanitary sewer system are problems for many communities. Through my various meetings and discussions with representatives of other cities, no one has an easy solution. It is my opinion that it is to our benefit to initiate the recommended program in lieu of spending thousands of dollars on the construction of a new storm sewer system. FGM:sm 2000 First Bank Place West Minneapolis Minnesota 55402 Telephone (612) 333-0543 Telecopier (612) 333-0540 Clayton L. LeFevere Herbert P. Lefler J. Dennis O'Brien John E. Drawz David J. Kennedy Joseph E. Hamilton John B. Dean Glenn E. Purdue Richard J. Schieffer Charles L. LeFevere Herbert P. Lefler III James J. Thomson, Jr. Thomas R. Galt Dayle Nolan Brian F. Rice John G. Kressel James M. Strommen Ronald H. Batty William P. Jordan Kurt J. Erickson William R. Skallerud Rodney D. Anderson Corrine A. Heine David D. Beaudoin Paul E. Rasmussen Steven M. Tallen Mary F. Skala Christopher J. Harristhal Timothy J. Pawlenty Rolf A. Sponheirr LcI orrc LcflcI henlicd\ O,Brien K; Dram a Proic"wr.I: A. ociaiiun November 30, 1987 Mr. Fred Moore Director of Public Works City of Plymouth 6400 Plymouth Blvd. Plymouth, MN 55447 Re: Donohue Storm Sewer Study Proposals Dear Fred: At its meeting on November 2, 1987, the city council asked me to report to you concerning the legal ramifica- tions of one of the options contained in the Donohue con- sulting firm in its report pertaining to the Amber Woods/Hughes Additions drainage problems. Alternative 2 of the Donohue report proposes that the city require property owners to reroute their sump pumps from the city's sanitary sewer system and instead discharge the water so that it will flow into city streets, where it will eventually flow into the storm water drainage system. The report notes that in winter nonths the water is likely to freeze in the street before it reaches the storm sewer system. Cities are immune from claims based on snow or ice conditions on public streets or sidewalks, except when the condition is affirmatively caused by the negligence of the city. Minn. Stat. Sec. 466.03, subd. 4. If the city council adopts Alternative 2, and if water from one of the sump pumps freezes in the street,, resulting in an accident, there is some risk that the city would not be immune from liability. A court or jury might find that the city affirmatively and negligently created, or contributed to the creation of, the icy condition by requiring property owners to discharge water into city streets when it was foreseeable that the water would freeze during winter months. The city's risk of liability is significantly reduced if the city merely requires the property owners to discon- nect their sump pumps from the sanitary sewer system, Mr. Fred Moore November 30, 1987 Page 2 without specifying where the property owner should discharge the water. In that instance, any property owner who discharges water into city streets would be acting independently rather than at the direction of the city council. In deciding whether to adopt Alternative 2 or one of the other alternatives proposed in the Donohue report, the city council should weigh the potential increased risk of liability as one factor in its decision-making process If you have any questions, please call me. Sincerely, LeFEVERE, O'BRIEN J mes J. JJT:cah LEFLER, KENNEDY, DRAWZ Thomson, Jr. cc: James G. Willis wyului vwi ii 1,1cct_111y RESOLUTION NO. 87-746 November 2, 1987 SETTING CONDITIONS Page 339 DIVISION AND REGAb,ING A SUBDIVI- LOT DIVISION Fiber LAND BY METES AND BOXS DESCRIP- VARIANCE, JOHNSON & MOTION was made by Councilmember Zitur, seconded by Councilmem- RESOLUTION NO. 87-744 Crain,o adopt RESOLUTION NO. 87-744 AWARDING BID FOR AWARD BID RECYCLING 15,000 RECYCLICONTAINERS to "We Recycle, Inc." in the amount CONTAINERS of $4.91 each forte total amount of $73,650. Item 6-N Motion carried on a Nil Call vote, four ayes. Councilmember Vasiliou voted nay. `N MOT10N was made by Councilmefhkr Sisk, seconded by Councilmember RESOLUTION NO. 87-745 Zitur, to adopt RESOLUTION N0:',Q87-745 APPROVING VARIANCES FROM SUBDIVISION CODE VARI- THE SUBDIVISION CODE AND URBADEVELOPMENT POLICY RESOLUTION ANCE, LAND DIVISION NO. 75-664 AND LAND DIVISION FOR 3b SON & SCHROEDER PARTNERSHIP JOHNSON & SCHROEDER 87077). (87077) F Item 6-0* Motion carried on a Roll Cal A.-ote, five 'ayes. MOTION was made by Courlolimember Sisk, secoi`ided by Councilmem- RESOLUTION NO. 87-746 ber Zitur, to adopt RWLUTION NO. 87-746 SETTING CONDITIONS TO SETTING CONDITIONS BE MET PRIOR TO FIL THE LOT DIVISION AND REGAb,ING A SUBDIVI- LOT DIVISION SION VARIANCE AND IVISION OF LAND BY METES AND BOXS DESCRIP- VARIANCE, JOHNSON & TION FOR JOHNSO & SCHROEDER PARTNERSHIP (87077). ', R SCHROEDER 87077) Item 6-0* Motion carr'fed on a Roll Call vote, five ayes. REPORTS OF OFFICERS, BOARDS AND COMMISSIONS Thomas Wolf, Project Manager with Donohue & Associates, Inc., presented a synopsis of their report which was submitted on October 22. The purpose of the survey was to examine the sani- tary sewer system to locate infiltration and inflow sources within the study area, Amber Woods. The slides he presented were typical of what they look for and were not of the area they surveyed in Plymouth. He summarized the findings and alterna- tives. Discussion followed on the amount of water being put into the sanitary sewer per sump pump. Director Moore stated the study to date has cost approximately 17,500. Discussion continued on at what point to discuss the alterna- tives with the Amber Woods Homeowners Association. Manager Willis noted that it is illegal to have connections to the sanitary sewer. All consumers of the sewer service are pay- ing for the treatment of that water because it goes to the treatment plant in St. Paul. This will only get worse as rates increase. Mayor Schneider asked for more information from the street report for this area to brief the Council on the remaining street life expectancy. The Public Works Director's analysis of the storm sewer capacity in the area, and the legal ramifica- tions of letting the water flow into the street (including freezing and how prevalent would it be and where.) SEWER SYSTEM REPORT I/I ANALYSIS, AMBER WOODS AREA Item 7-A riegu lar Lounci L Meet tng November 2, 1967 Page 340 Councilmember Sisk asked for an estimate of how much storm water is going to St. Paul for which City residents are paying and what the reduction would be on that charge with the various alternatives. He wants an estimate of the appreciation to home- owners property by mitigating the water problem on their prop- erty. Mayor Schneider also wants to know how this cost would be assessed. He established a study meeting for December 7 at 5:00 p.m. to discuss this further. MOTION was made by Councilmember Sisk, seconded by Councilmember RESOLUTION NO. 87-747 Zitur, to a t RESOLUTION NO. 87-747 AUTHORIZING RETENTION *•"` RETENTION OF EHLERS EHLERS AND ASSO TES FOR CONSULTIVE SERVICES REGARDING DEVELOP- & ASSOC. SENIOR MENT OF SENIOR CIT N HOUSING. CITIZEN HOUSING Item 7-B* Motion carried on a Roll'" -Call vote, five ayes. MOTION was made by Councilmem6er,.Sisk, seconded by Councilmember RESOLUTION NO. 87-748 Zitur, to adopt RESOLUTION NO. 87tg48,AMENDING DEVELOPMENT CONT- AMENDING DEVELOPMENT— RACT FOR PARKERS LAKE 2ND ADDITJ,t` (87006) changing sidewalk CONTRACT, PARKERS LAKE width to 5 ft. / "`.a 2ND ADDN. (87006) 4. Item 7-C* Motion carried on a Rol all vote, five ayes._, The meeting adjo fed at 10:00 p.m. City Clerk Donohue SEWER SYSTEM EVALUATION SURVEY AMBER WOODS/HUGHES ADDITIONS (DISTRICT 21) CITY OF PLYMOUTH, MINNESOTA A. Sewer System Evaluation Survey (SSES) - systematic examination of sanitary sewer system to locate infiltration and inflow (I/I) sources within the District 21 study area, determine the flow rate from each source identified and determine the cost of correction to rehabilitate infiltration and inflow sources within the District. 1. Authorization to Proceed - letter dated March 27, 1987. B. Elements of SSES to be Completed 1. Physical Survey and Records Review - conduct necessary engineering inspections in order to appraise inflow potential at sanitary manholes. a. Physically inspected 61 manholes to document loca- tion, size, type of construction, depth from surface to sewer invert, structural condition, groundwater height, location of visible sources of I/I and special problems or conditions that may exist. Appendix A - Manhole Location and Inspection Report - documents results of said inspections. b. Review location to identify covers subject to flooding or surface water inflow. C. Evaluate inflow sources such as frame/masonry interface of each manhole. d. Review flow records, past records, past reports including City's 1982 I/I Analysis Report and records documenting I/I conditions in the sanitary sewer system. e. Findings: 1) 48 of 61 manholes (79%) - evidence of infiltration in form of stains and deposits, generally not cost effective to rehabilitate. 2) 32 of 61 manholes (52%)- potential inflow sources, not sealed between manhole frame and chimney interface and/or frame misaligned. 3) No structurally defective manholes found. 4) No manholes subject to ponding or surface runoff found. Donohue 2. Smoke Testing - locate and identify sources of I/I such as roof, yard and area drains, and storm sewer catch basins and manholes which may be directly connected to the sanitary sewer system and to estimate degree of inflow contribution from manhole frame/chimney interface defects. a. Smoke tested 100% of sanitary sewer system within District 21 (approximately 14,000 lineal feet). b. Findings 1) 5 instances of smoke from pavement cracks adjacent to sanitary manholes. Confirming unsealed manhole frame/chimney interface. 2) 1 uncapped service lateral cleanout. 3. Building Inspections - to determine if foundation drains, sump pumps, area drains, downspouts or other building conditions are contributing I/I to sanitary sewer system. a. Attempted inspections at 210 buildings of which 207 were residential units. b. 166 buildings (79%) actually inspected, 44 inspec- tions not completed (39 residents not home, 5 home- owners refused entry). C. 3 attempts were made during week at those buildings where no one was home at time of inspection, final follow-up attempt made on Saturday, August 22, 1987. d. Findings (Appendix B - Building Inspection Report): 1) 43 of 166 sump pumps (26%) connected to sanitary sewer. 2) 11 additional sumps to sanitary sewer assumed 26% of 44 buildings not inspected). 3) 10 cases piping configurations from sump pump temporarily rerouted prior to inspections. 4. Defect Rehabilitation Methods and Costs a. Manhole frame/chimney interface - install internal rubber boot at interface; 32 manholes @ $431/defect = $13,800. b. Service lateral cleanout - cap or seal exposed structure. 1 cleanout @ $100/defect = $100. C. Sump pump disconnection - Donohue 1) Alternative 1 - reroute discharge piping to ground surface. 54 sump pumps @ $75/sump pump = $4,050 o Advantages: inexpensive. easily completed. reduce basement backups during peak wet weather periods. o Disadvantages: yards may remain saturated for extended periods. ponding of yards possible to greater degree than currently exists. recycling process of clearwater due to migration. surface discharges susceptible to freezing during colder months. 2) Alternative 2 - reroute discharge piping to ground surface in front of house at street or driveway. 54 sump pumps @ $300/sum pump = $16,200 o Advantages: discharge farther from building reduces recycling process. relatively inexpensive and easy to complete. reduce basement backups during peak wet weather periods. removes discharge from back yards and away from homes. o Disadvantages: surface discharge susceptible to freezing during colder months. discharge near roads and drives may cause icing conditions on driving surfaces. discharge near pedestrian ways may create hazardous situation. existing stormwater drainage facilities may become overburdened. 3) Alternative 3 - discharge to existing storm, or new 12" storm if no existing storm available. New installation requires 12 -inch plastic pipe behind street curb and gutter; intended for sump pump discharge only; storm laterals from each residential building to new collector, installation on 1 side of street only; approximately 4 feet deep. Donohue For existing storm sewered areas, storm laterals required from building to main. Total cost = $639,500 (207 units) o Advantages: eliminates basement sewage backups during peak wet weather periods. reduces ponding of streets and yards. eliminates icing and freezing conditions in yards, on pedestrian ways and on driving surfaces. o Disadvantages: high installation cost. inconvenience to local residents during extended construction period. significant surface disruption and restoration required. 4) Alternative 4 - discharge to existing storm, or new 8" storm if no existing storm available. New installation requires 8 -inch plastic pipe behind street curb and gutter; intended for sump pump discharge only; storm laterals from each residential building to new drain pipe; installation both sides of street; approximately 4 feet deep; install insulation top and sides; install cleanouts every 100 feet. For existing storm sewered areas, storm laterals required from building to main Total Cost = $601,100 (207 units) o Advantages: eliminates basement sewage backups during peak wet weather periods. reduces ponding of streets and yards. eliminates icing and freezing conditions in yards and on pedestrian ways. o Disadvantages: high installation costs. inconvenience to local residents during extended construction period. significant surface disruption and restoration required 5) Alternative 5 - surface discharge during warmer months, discharge to sanitary sewer during colder months. Installation of T -valve on sump pump discharge line required to divert flow to appropriate source. Donohue For existing surface discharge - piping to stationary tub or floor drain required. For existing sanitary sewer discharge - piping to surface required. Total Cost - 207 units @ $400/unit = $82,800 o Advantages: lower installation costs than new storm sewer. reduces or eliminates basement sewage backups during peak wet weather periods. reduces or eliminates icing conditions associated with surface discharge in colder months. o Disadvantages: requires approval by local authorities and the Metropolitan Waste Control Commission requires extensive educational program to ensure understanding of procedures and goals. requires nearly 100 percent compliance for success of program. requires routine inspections by City per- sonnel to confirm proper discharge at appropriate time. 6) Alternative 6 - expand existing storm sewer system to ensure sufficient capacity to convey stormwater runoff and I/I from sump pumps. Total Cost - cannot be determined at this time. o Advantages: eliminates basement sewage backups during peak wet weather periods. reduces ponding of streets and yards. reduces or eliminates icing conditions associated with surface discharge in colder months. o Disadvantages: most costly of all alternatives. inconvenience to local residents during extended construction period. significant surface disruption and restoration required. requires detailed study of existing storm sewer, storm drainage system, and down- stream areas where flooding may occur prior to implementation. Donohue SUMP PUMP ANALYSIS CITY OF PLYMOUTH AMBERWOODS/HUGHES SUBDIVISIONS Alternative No. 1 (54 units) Surface discharge 3 feet from foundation 4,050 Alternative No. 2 (54 units) Surface discharge Front of house to street 16,200 Alternative No. 3 (207 units) Discharge to storm 12 inch collector pipe 639,500 Alternative No. 4 (207 units) Discharge "mini" storm system 601,100 Alternative No. 5 (207 units) T -valve system 82,800 Alternative No. 6 Expand existing storm sewer system Cost N/A C. I. STEPS (E Ite" CTR NEENAH R- MSO-C- oR EQUAL_ 42" DIA. PRECAST MANHOLE SEG -TION X02 -IAA ATE V!-v..-.- - - --"-V, --- - ---- m] PRECAST MANHOLE DE:TAIL% Af