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
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