CR 88-216 Storm Sewer Recommendations
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November 8, 1968
Council Report 88-216
STORM SEWER RECOMMENDATIONS
RETAINING OF DESIGN ENGINEER
mPooed Action.
Staff recommends the f'ollowing motion: Hove that the Engineer'lS
reoommendations for storm sewers on 6th Avenue and on County Road 3 be
approved and that the Ci ty Manager be authorized to enter into a
contract with an engineering firm to. design and superviae oonstruotion
of those sewers.
This nction would begin the process of constructing sewers to re11e.e
flooding conditions ia these two areas.
Overview.
A complete study of the storm sewers in Hopkins was ordered by the
Council in 1987. The first report was presen tad to the CouDcil in
August, 1988. This report recommended the installation ot a large
sever on 6th Avenue from 1st Street North to Valley Park and tbence
into Nine Mile Creek. The r~port also recommended the installation ot
a box oulvert crossing County Road 3 at 13th Avenue South. This box
oulvert vould replace the existing culvert at that location.
Statt will be soliciting proposals f~om qualified engineeriDI tirms to
do the design work alld to supervise the installation of these systeMs.
Reco..endation will be to direct tbe City Manager to enter into It
oontract with a firm to do th1~ work.
P~i.arY
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Issues to Consider.
Should the recommendations of the engineer be
implemented?
Should the projects be combined?
How should the engineer be selected?
What 1s the timetable for plans and construction?
What are the sources of funding?
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Support1n~ Information.
Map of proposed, projeots
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CR:88-216
Page 2
Baokground.
Flooding from rainstClrms haa been an inoreasing problem in recent
years with tho continued buildup of the City. The City Couno11 111
1987 ordered that a oomplete Stor~ Water Management Flan be developed
for adoption. Two portions of that plan haye been completed and
presented to the Council.
One part of the plan addresses the flooding problem around 6th Avenue
North "nd 1st Street North and around 6th Avenue South around 2nd
Street Sou th. The engineer recommended tha t a large 8 tora .ewer be
installed from 6th Avenue North, south along 6th Avenue to the alley
south of 7th Street South, and thence east into Valley Park into a
stilling basin. From there the water would go into Nine Mile Creek.
The recommendation ia to control the flooding during a 10 year stor..
The estimated costs for this storm interval is 1.15 million dollars.
Te adequately handle a 25 year storm, the estima~8d cost is 3.25
million dollars. Based on the difference in cost, it 1s recoa.ended
that the design would be to control flooding at the 10 year interval.
At that rate, some flooding would occur during heavier storms.
A second part of the plan addresses the flooding that occurs near 13th
Avenue South, north of County Road 3. This area receives runoff fro.
zost of the central part of the business district whioh, during heav,
rainfalls, doesn I t all get. in to the catch basins and stora water
pipes. Yhe present culvert across County Road 3 has a design capacity
of approximately 250 cubic teet per second (cfa).
The engineer has recommended that a new culvert be plaoed seross the
county road with a capacity of 360 cfs. Tbis would be the lar.eat
that would be allowed by the Hine Mile Creek Watershed District. The,
have placed a control at the Chicago Northwestern Railroad oUlvert,
saying that no more water is allowed into south Hopkins than can drain
through the an culvert. The recommended Culvert would control
flooding during a ten year sto~m with a minor amount of flOOding.
Analysis.
Items that the Council should consider are:
o Should the recommendations of the engineer be implemented?
The engineer has recommended a system that would control flooding tor
a ten year storm. For heavier storms, ~ome flooding would occur, tbe
am~unt of which would depend on the intensity of the storm. For those
beavier storms, the capacities of the pipef] would allow the flooded
areas to drain at a much more rapid rate. The staff agrees with the
recommendations of the engineer in designing for a ten year event.
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CR:88-216
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Should the projects be combined?
The projects should be combined for EngineeriQg purposes. There will
be qui te a few meetings wi th the Watershed and wi th the County and
others. These could all be combined during the design process. The
stafr recommends that only one engineering firm be 001l1lie810ne<1 to
design and supervise the installation of the storm sewers.
The two projsct8 are differant in the type of WQrk and pipe to be
iostallede the working conditions and the eqUipment needed. It .&7 be
to the City's best intereat to have two contractors working on the two
projects. As t:f.ming 1s very important to the City to get tbese
projects completed as rapidly as Possible, the staff recommends that
the two projects be bid separately aod contracted separately.
o How should the engineer be selected?
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Section 4 of the Hopkins Legislative Policy Manual gets out gUidelines
and requirements for contracting with consultants on a non-recur1ng
basis. Section 4.02 states that "All other DOD-reCurring consultant
service oontracts shall be approved by the City Council." Statt 1.
requesting that that provision be waived tor this project in tbe
interest of timing to get the projects started as soon as po.sible.
Statt ViII be requesting Scope ot Service Proposala trom thrae
engineering t1rms tami~iar with tbe area and capable in the deSign and
construction ot storm sewe~8. Statt would then recommen~ on. fira to
do the work in vol ved, based on experience, 8 tatt'J,ng, tiaetabl. and
tees. Staff i8 reques ting that the Ci ty Manager be authorized to
enter into a contract for services without prior approval ot the City
Council. The three i"irlJ'5 that will be con taated are ReM. the fira
that did the stUdy; TKDA, the firm that is presently retained as City
Engineer; and Barr Engineering, the engineer for the Nine Mile Creek
Watershed.
o What is the timetable for plans and consruction?
The timetable set up ~or the implementation of recommendations in the
Storm Water Management Plan is to bave relief for potential flooding
in place in 1989. To achieve that timetable7 it is important to keep
the ball rolling.
Staff would like to be working with a consultant in the planniog stage
as soon as possible so plana could be completed for early spring award
of contracts. The planning stage will be long in that thcl'e are
numerous agencies to contact and to work with to get approval before a
design can be completed. If contracts can be awarded in early spring,
the projects should be completed in early summer, 1989.
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CR:88-216
Page 4
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What are the sources of fuca~ng for thase projeots?
So.. funds are available in the Storm Sewer fund. The a.ount vill not
be adequate for the proJeots reoommended above and tor other projeota
tbat ar$ anticipated. It 1$ suggested that a Storm Sever Ot1litl be
aeveloped. This utility would cbarge montbly charges tor stor. aever
a1st.. in~t&ll&tion ~nd ma1ntenace. The rates would be aa tbe Couna11
would eet aa needed. Utilities ot this type are now 1n exist.noa in
Bloo.lngtoD, Edina, Ricb~1eld and Roaeville.
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