7. Pinewood Circle Drainage UpdateI MEMORANDUM
CITY OF �
CHANHASSEN
690 COULTER DRIVE * P.O. BOX 147 • CHANHASSEN, MINNESOTA 55317
(612) 937 -1900 • FAX (612) 937 -5739
1 TO: Charles Folch, Director of Public Works
FROM: Dave Hempel, Assistant City Engineer
1 DATE: June 5, 1996
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ALTERNATIVE A
the grade from Mr. Larson's
nately 0.5 feet of fall over 350 feet
% to 6 %) between Mr. Larson's
s also created a drainage pond on
lem. A roof drain in the front of
m should be redirected away
Upon review of the i ce Water Management Plan (SWMP), a trun sewer system
is proposed in the future for thi convey runoff fro opment The
SWMP estimates the cost of this trunk sys $8 epared a revised cost
estimate which follows the SWMP plan for the o art. The pipe length has been reduced to a
point which is only needed to for
with this s property. This alternative would be a
component of the overall final trunk storm sewe ystem in accordance with the City 's SWMP.
The final trunk sewer system would not need to be constructed until the area develops into an
urban setting. The existing plat dedicated a 10 -foot wide drainage and utility easement centered
upon the common property lines. An additional 10 feet of easement will be required with all of
the alternatives. In addition, temporary construction easements would be needed from three
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Charles Folch
June 5, 1996
Page 2
properties easterly of Mr. Larson. This alternative would be a permanent solution for the ground
water and surface water runoff from the area. The estimated cost of this alternative is $56,228,
assuming that all disturbed areas would be sodded. Replacing the sod with seed and mulch would
be a cost savings of approximately $9,000. It is likely that storm sewer assessments would need
to be levied to fund a portion of the costs.
Cost Esti - Altern A
1. 200 L.F. - 24" RCP @ $ 35/ L. F ................................................ ............................... $7,000
2. 200 L.F. - 27" RCP @ $ 40/ L. F .................................................. ............................... 8,000
3. 175 L.F. - 30" RCP @ 45/ L. F . .................................................................................. 7,875
4. 1- 30" FES @ $ 1250 /EA ................................ ............................... ..........................1,250
5. RIPRAP - 5 C.Y. @ $ 45/ C. Y ........................... ............................... ............................225
6.
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8A.
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12.
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1- 60" DIAM: MANHOLE @ $1,850 EA ....... ............................... ..........................1,850
2 - 48" DIAM. MANHOLES @ $1,300 EA ..... ............................... ..........................2,600
RESTORATION SEED/MULCH - 0.80 AC. @ $1500 /AC . ..................................... 1,200
SOD - 3,900 S.Y. @ $ 2. 75/ S. Y . ............................................................................. 10,648
PERMANENT DRAINAGE EASEMENTS - 6,000 S.F. @ . 75/ S. F . ........................ 4,500
TEMPORARY CONSTRUCTION EASEMENTS - 6,000 S.F. @ .10 /S.F ..................600
TRENCH AGGREGATE = 20 TONS @ $9/ TON ............................ ............................180
15% ENGINEERING FEES ............................ ............................... ..........................6,900 ,
10% CONTINGENCY .................................... ............................... ..........................4,600
GRAND TOTAL W /SOD VS. SEED /MULCH ..... ............................... ........................ $56
GRAND TOTAL W /SEED/MULCH VS. SOD ..... ............................... ........................ $46
ALTERNATIVE B
This alternative involves extending-a storm sewer from Lukewood Drive in the Minger Addition
which is adjacent to Timberwood Estates. This alternative will only address potentially ground
water in the area south of Mr. Larson's pond. The problems with this alternative is the grade
between the existing storm sewer in Lukewood Drive (942.8) and the existing grade in Mr.
Larson's property (946.4±) and the limited capacity of the storm sewer. This alternative proposes
to extend a 12 -inch RCP storm sewer on the common property line of Lots 4 and 5, Block 1,
Minger Addition from the existing catch basin in Lukewood Drive. This construction would
result in the loss of a couple of significant oak trees along the property line. Additional drainage
easements would also be required with this proposal. The estimated cost of this alternative is
$19,765. 'The drawback of this proposal is that it limits the use of the drainage system to really
only ground water. There are concerns with the depth of the drainage system (approximately 2'h
r
' Charles Folch
June 5, 1996
' Page 3
'
feet). At this depth the pipe would be subject to freezing in the winter and therefore not a year -
round solution. In addition, it may be very difficult to acquire easements from the property
owners in Minger Addition due to the significant tree loss.
Cost Estimate - Alternative B
1.
CONNECT TO EXISTING SYSTEM
$250
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2.
........................................ ...............................
200 L.F. - 12" RCP @ $28/L.F.. ..5,600
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1 - 27" DIAM. MANHOLE .............................. ............................... ............................750
4.
SOD - 467 S.Y. @ $ 2. 75/ S. Y . ..................................................................................
1,285
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EASEMENTS - 2,000 S.F. @ $ 1. 50/ S. F .......... ............................... ..........................3,000
6.
TREE REPLACEMENT ................................. ............................... ..........................5,000
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7.
10% CONTINGENCY .................................... ............................... ..........................1,500
8.
15% ENGINEERING FEES ............................ ............................... ..........................2,380
GRAND TOTAL ..................................................... ............................... ........................$
ALTERNATIVE C
This alternative involves constructing an open drainage ditch from Mr. Larson's easterly property
line out towards Timberwood Drive basically using the same alignment as Alternative A. The
drainage ditch was designed with a 3 -foot ditch bottom with 3:1 side slopes. Permanent and
temporary construction and drainage easements would also be needed to be acquired with this
proposal. One of the drawbacks of this alternative would be the wet, open ditch year round. This
alternative is very cost effective in comparison to the storm sewer (Alternative A). The cost of
this proposal is $19,705
Cost Estimate - Alternative C
1. EXCAVATION - 650 C.Y. @ $ 51C. Y ..................................... ............................... $3,250
2. PERMANENT EASEMENTS - 6,500 S.F. @ .75 /S.F . ............................................. 4,875
3. TEMPORARY CONSTRUCTION EASEMENTS - 6,000 S.F. @ .10 /S.F . .............. 6,000
4. SOD - 2,800 S.Y. @ $ 2. 75/ S. Y . ............................................................................... 7,700
5. 10% CONTINGENCY ............................................................. ............................... 1,640
5. 10% ENGINEERING FEES ..................................................... ............................... 1,640
GRAND TOTAL ..................................................... ............................... ........................$19,705
Charles Folch
June 5, 1996
Page 4
FINANCING
Allocation of funds for this type of project is very limited. The project specifically addresses the
needs of a single property owner initially. Assessing all or a portion of the cost of this work as a
public improvement project would be a possibility. Typically, storm drainage improvements are
assessed back at 50% to the benefiting properties. The contributing drainage area is
approximately 17 acres. The other 50% has been paid for by the City. SWMP funds have been
allocated toward a 5 -year CIP. Funding this project with SWMP funds may jeopardize other
projects earmarked for this year. With the platting of Chanhassen East Business Center (Dell
Road/Lake Drive East), the SWMP fund will owe the developer approximately $95,000 that was
not projected in the 1996 SWMP budget. The Timberwood Estate residents are charged
quarterly SWMP fees at a rate of $5.00/lot (38 lots). This generates a revenue of $760 /year. The
question is also raised whether or not the use of SWMP funds for this individual use would set a
precedent in resolving other individual drainage problems throughout the City.
CONCLUSION
Given the financial constraints of the SWMP budget and the time of year, in order to address Mr.
Larson's problem staff recommends either Alternatives A or C be pursued with a portion of the
costs assessed back to the benefiting property owners. Alternative C would prepare the area for
future trunk storm sewer when the conditions warranted. Alternative A or C could be completed
yet this year. If the project costs are proposed to be assessed, the public hearing process will need
to be initiated by the property owners with a petition to the City. With all three alternatives Mr.
Larson will still need to extend a drain file or re -grade his property to provide for drainage away
from his home. If it is the City Council's desire to see this matter resolved as a public
improvement project, staff recommends that a neighborhood meeting and public hearing be held
to discuss the alternatives and potential special assessment necessary to complete the work.
Attachments: Location maps
c: Mr. Richard Larson
g engld"e'"Mm Am
O.FFINAL ENGINEERING Copy
Received
Revision No.
APProved City Engineer
Date ( 'P /& 4A
APProved by City Councli
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