HomeMy WebLinkAbout9A - Fish Point Park Pond Outlet Channel
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MEETING DATE:
AGENDA #:
PREPARED BY:
AGENDA ITEM:
DISCUSSION:
CITY COUNCIL AGENDA REPORT
AUGUST 6, 2007
9A
ROSS BINTNER, WATER RESOURCES ENGINEER
CONSIDER APPROVAL OF A FEASIBILITY REPORT REGARDING TWO
OPTIONS FOR THE FISH POINT PARK POND OUTLET CHANNEL.
Introduction
The purpose of this agenda item is for the City Council to approve one of two
construction alternatives presented in the attached Feasibility Report for the
improvement of the Fish Point Park pond outlet and order plans and
specifications for the preferred alternative.
Historv
As part of the CIP process this project was added to the CIP in 2006 for
construction in 2007. This drainage channel has been in place in some
capacity since before the 1950s. This region was developed in the mid 1970s.
Since that time the area has not changed significantly. In the late 1990s the
City improved the pond in Fish Point Park to further reduce the flow rate
through the channel. During the 2005 reconstruction project, the pond was
once again expanded to further cut peak flow rates. Since the channel
historically has drained this area, the City is not obligated to obtain easements
for this area. City staff and City Council have made fair offers through this
process to secure easements. Where public benefit and private benefit align,
costs can be justified however none of the proposals guarantees that the
property owners will sign easement documents.
The City Council requested that the City Engineer study costs and benefits of
different pipe solutions of no more than approximately 30 feet and asked that
the solutions include the granting of permanent easements and be acceptable
to both adjacent land owners.
Current Circumstances
The Engineering Department met with the affected property owners to gain
input on the design prior to creation of the revised Feasibility Report. After
sketching out two concepts, residents were invited back to review the two
options and provide further opinions. The attached Feasibility Report includes
a 20-foot pipe option and a 65-foot option as the property owners indicated
they would not support the 20-foot option. Attached is the Feasibility Report
describing both options.
www.cityofpriorlake.com
Phone 952.447.9800 / Fax 952.447.4245
ISSUES:
The following two options were created and studied at the request of the City
Council and are the subject of the attached Feasibility Report.
Option 3A: Construct Pipe approximately 20' within existing channel.
Option 3B: Construct Pipe approximately 65' to provide additional
resident benefit.
The scope of the latest Feasibility Report (Fish Point Park Elective Pipe
Options) went beyond that of the Preliminary Report by adding the goals of
improving the road slope for public safety and minimizing flow impacts to the
retaining wall to the existing goal of creating a stable flow path.
Prior to creating these two options, staff met with the residents to hear their
opinions on what would constitute an acceptable solution. Residents preferred
Option 38 and requested some changes and additions that would provide
additional private benefit.
FINANCIAL
IMPACT:
If permanent easements are granted, the City will take responsibility for the
drainage path in the future. The financial impact will vary dependent on the
option chosen. The process thus far has consumed 240 staff hours with an
estimated value of $7,200 and expenses of $934 for a wetland delineation
report and rental of survey equipment. Total cost to date is estimated at
$8,134.00.
Additional staff time for permitting, process, and construction management will
be needed under either option and additional expense will be incurred under
Option 38 for wetland permitting. This additional expense for wetland
permitting is estimated to cost an additional $900.00 in staff and consultant
time.
Estimated costs exclusive of staff time:
Option 3A is estimated to cost $12,724.50
Option 38 is estimated to cost $24,185.50
Resident-requested changes and additions are estimated to cost $2,690.50
over and above the cost estimated for option 38.
Comment From Citv Attornev
Under the "public purpose doctrine," the City cannot lawfully expend public
funds to create a private benefit. The City Engineering Department has
designed improvements to the drainage channel that will protect against
shoreline and channel erosion. It is the City's obligation, relying on the expert
advice of its staff and consultants, to determine what design and/or
methodology meets the goals of stabilizing and maintaining the channel and
increasing roadway safety. If the property owners in the vicinity of the channel
have a preferred design that (1) costs more, but (2) does not provide
appreciable benefit in relation to the cost - the Council must take into
consideration the "public purpose doctrine."
An alternative to the City ordering plans for an option that involved the
installation of a 20' or 65' pipe, is for the property owners to petition for their
preferred pipe solution and agree to have the difference between the
Engineers' recommendation and the pipe solution specifically assessed
against their property.
ALTERNATIVES:
1. Approve a resolution accepting the Feasibility Report and ordering the
preparation of plans and specifications for the Option 3A, 20' in-channel
pipe extension, contingent upon gaining easement for construction.
2. Approve a resolution accepting the Feasibility Report and ordering the
preparation of plans and specifications for the Option 38, 65' in-channel
pipe extension, contingent upon gaining easement for construction.
3. Deny this item for a specific reason and provide staff with direction.
4. Defer action and consider a special assessment project.
5. Table this item until some date in the future.
6. Remove this project from the 2006 CIP.
RECOMMENDED
MOTION:
As the Council deems appropriate.
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4646 Dakota Street SE.
Prior Lake, MN 55372-1714
RESOLUTION 07 -xx
A RESOLUTION APPROVING A FEASIBILITY REPORT FOR THE IMPROVEMENT OF
THE FISH POINT PARK POND OUTLET AND ORDERING PLANS AND SPECIFICATIONS
FOR ITS IMPROVEMENT.
Motion By:
Second By:
WHEREAS, The improvement of the fish Point Park pond outlet was include in its Capital
Improvement Plan, and;
WHEREAS, Improvement of this outlet will promote a stable and safe flow path that lessens risk of
property damage, and;
WHEREAS, The City will attempt to gain permanent easements frbm nearby residents for the
perpetual maintenance of this flow path, and;
WHEREAS, The project will proceed only if permanent easements are obtained, and;
WHEREAS, The improvement of the outlet will improve safety on the slope near fish Point Road.
NOW THEREFORE, BE IT HEREBY RESOLVED BY THE CITY COUNCIL OF PRIOR LAKE,
MINNESOTA as follows:
1. The recitals set forth above are incorporated herein.
2. The Feasibility Report titled "Feasibility Report for the City of Prior Lake Fish Point Park Pond
Outlet Elective Pipe Options" and dated July 27,2007 is hereby approved.
3. Council hereby approves Option #_'
4. The Staff is directed to obtain easements for said improvements.
5. Once easements are granted, the Staff is directed to prepare plans and specifications for said
improvements.
PASSED AND ADOPTED THIS 6th DAY Of AUGUST 2007.
YES
NO
Haugen Haugen
Erickson Erickson
Hedberg Hedberg
LeMair LeMair
Millar Millar
Frank Boyles, City Manager
www.cityofpriorlake.com
Phone 952.447.9800 / Fax 952.447.4245
FEASIBILITY REPORT
FOR THE CITY OF PRIOR LAKE
FISH POINT PARK POND OUTLET
ELECTIVE PIPE OPTIONS
JUL Y 2007
I hereby certify that this Feasibility Report was prepared by me or under my direct supervision
and that I am a duly licensed Professional Engineer under the laws of the State of Minnesota.
~~
7-- 27- 01
Date
Ross T. Bintner, P.E.
Reg. No. 44570
G:IWater ResourceslDrainage Issuesl07-02 Fish Point Park OutletlFish Point Park Elective Pipe Report.doc
Page 1 of 4
INTRODUCTION
This report was requested by the Prior Lake City Council to study feasibility of providing a pipe
extension to the existing road culvert draining Fish Point Park Pond. This report goes into
further detail on the previous report titled "Preliminary Report for the City of Prior Lake Fish
Point Park Pond Outlet."
BACKGROUND & HYDROLOGY
The proposed project area is shown on Exhibit 1. The existing channel location is southwest of
Fish Point Road and South of Frost Point Circle. Currently the drainage system includes a pond
outlet structure, 45' of 30" culvert, and 220' of unimproved channel. The outlet structure,
culvert and channel drain the pond in Fish Point Park. The Fish Point Park outlet channel drains
87 acres of single family residential area. Two ponds in the park function to dampen peak rates
draining from the subwatershed. The outlet pipe from the downstream pond drains under Fish
Point Road and has capacity to carry the 25-year storm (Runoff from a 4.8" rainfall in normal
conditions, over 24 hours). The outlet channel from the pipe outlet to Lower Prior Lake is a
natural channel with miscellaneous vegetation ranging from grasses, to shrubs, to trees. A flow
constriction exists at the mouth of the channel where it meets the Lake, this feature is primarily
made up of sandy soil and is well vegetated with tall shrubs. It is this tlow constriction that is
responsible for much of the risk to private property.
DISCUSSION OF AL TERNA TIVES
Options I and 2 were the focus of the previous report and were titled thus:
Option 1: Regrade and Stabilize Open Channel
Option 2: Construct Pipe to Prior Lake
During its consideration of the matter, the Prior Lake City Council deemed an extension
appropriate and requested that the Engineer look into different pipe options that extend pipe
approximately 30'. The resolution was premised off of remedying a potential safety issue for
retaining wall near the roadway, working with the nearby property owners and gaining permanent
easement for the outlet channel. As directed by Council, the Engineer completed a design
survey, worked with residents, and now proposes two additional options for discussion. Since
the original report the Engineer has preformed a survey of the site and a wetland scientist
delineated the extent of wetland in the channel. With this additional information and through the
use of specific design options, more accurate cost estimates are provided. Below are the two
options numbered and listed, followed by a summary of each.
Option 3A: Construct Pipe approximately 20' within existing channel.
Option 3B: Construct Pipe approximately 65' to provide additional resident benefit.
Each option consists of a storm water system consisting of concrete pipe designed to convey the
25-year storm event and a stabilized overtlow channel designed to convey the 100-year storm
event. The options vary in alignment and length of pipe. Option 3A is shown in Exhibit 2 and
Option 3B is shown in Exhibit 3. Cost estimates for each option follow in Exhibits 4 and 5.
Option 3A: Construct Pipe approximately 20' within existing channel.
Summary
This option consists of installation of approximately 20' of pipe within the existing channel. The
benefits to the public include improved safety on the road slope and a stabilized channel tributary
to Prior Lake. The benefits to the property owners include reduced length of retaining wall and
corresponding reduced future maintenance cost.
Engineering feasibility: This option consists of partial filling of the eXlstmg channel and
placement of a 30" pipe from the current outlet location to a point in the channel. Due to the
energy loss in the pipe bend and the additional length of pipe, there is expected to be a decrease
in flow capacity in the pipe; however it is expected to be minor. A bend will be placed in the
existing pipe and an attempt will be made not to disturb the existing curb line or road; however,
this may not be possible given the geometry of the current culvert. In addition to the bend,
approximately 20' of concrete pipe and apron will be installed.
Regulatory requirements: This alternative is required to meet DNR requirements, and State and
Federal wetland rules. This alternative also requires a Wetland Conservation Act permit for the
fill of approximately 50 sf.
Option 3B: Construct Pipe approximately 65' within existing channel to increase resident
benefit.
Summary
This option consists of installation of approximately 65' of pipe within the existing channel. The
benefits to the public include improved safety on the road slope and a stabilized channel tributary
to Prior Lake. The benefits to the property owners include an even greater reduced length of
retaining wall, an increase in usable lawn or landscaped area, elimination of an additional 50' of
channel that was seen as a nuisance, and the elimination of unwanted trees.
Engineering feasibility: This option consists of partial filling of the existing channel and
placement of a 30" pipe from the current outlet location to a point in the channel. Due to the
energy loss in the pipe bend, manhole, and the additional length of pipe, there is expected to be a
decrease in flow capacity in the pipe. A bend will be placed in the existing pipe and an attempt
will be made not to disturb the existing curb line or road; however, this may not be possible
given the geometry of the current culvert. In addition to the bend, approximately 65' of pipe and
apron will be installed as well as a 5.5' diameter manhole
Regulatory requirements: This alternative is required to meet DNR requirements, and State and
Federal wetland rules. Due to net fill being placed under 904.00, this alternative results in a
reduction of flood storage for Lower Prior Lake and results in a marginal increased risk of flood
events around the lake. A variance will be needed from City rules and the variance request will
be forwarded on to the Prior Lake Spring Lake Watershed District for their review and approval.
This option also proposes the fill of approximately 1000sf of wetland. This wetland will have to
be mitigated 2.5: I based on new revisions to the Wetland Conservation Act (WCA). This
application could be approved by the City Council as they are the Local Governmental Unit
(LGU) defined by the WCA.
ESTIMA TED COST
The estimated costs for Option 3A is detailed in Exhibit 4 and estimated costs for Option 3B is
detailed in Exhibit 5.
PROJECT SCHEDULE
Upon approval of this Feasibility Report and a recommendation of which alternative to pursue,
the Engineering Department will move forward with final design of the chosen alternative in
effort to maintain the following schedule:
Work item
Obtain Easements
Design
Advertise Bid
Bid
A ward Contract
Construction
Start Date
August
September
September
October
October
November
If work were done using City equipment and personnel, this project schedule would not include
bid or contract work and construction would take place based on staff availability.
CONCLUSION
This report details elective pipe options requested by the City Council. The goal of the previous
report was to address the stability of the channel only. The design has changed because the goal
of improving the safety of the slope near the road was added.
In requesting this report, conditions were put on the design by the City Council. Option 3A
represents a modest approach to solving both goals while keeping costs reasonable; however, it
may still fail to meet acceptability by the residents.
EXHIBIT 1
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FISH POINT PARK OUTLET
This drawing is neither a legally recorded map nor a survey
and is not intended to be used as one. This drawing is a
compilation of records, information and data from various
city, county and state offices and other sources. This document
should be used for reference only. No representation is made
that features presented accurately reflect true location. The
City of Prior Lake, or any other entity from which data was
obtained, assumes no liability for any errors or omissions herein.
If discrepancies are found, please contact the City of Prior Lake.
AERIAL IMAGERY IS FROM A SPRING 2003
FLIGHT FOR SCOTT COUNTY.
200
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EXHIBIT 4: ENGINEERS ESTIMATE
CITY OF PRIOR LAKE
2007 FISH POINT PARK OUTLET IMPROVMENTS - OPTION 3A
2007 FISH POINT PARK OUTLET IMPROVMENTS
ITEM# SPEC. REF DESCRIPTION UNIT QTY UNIT PRICE TOTAL PRICE
1 2021.501 MOBILIZATION lUMP SUM 1 $ 300.00 $ 300.00
2 2101.502 CLEAR AND GRUB (TREE >6") TREE 9 $ 150.00 $ 1,35000
3 2104.501 REMOVE EXISTING SEWER PIPE (STORM) UN FT 8 $ 9.00 $ 72.00
4 0 REMOVE RETAINING WALL UN FT 50 $ 9.00 $ 450.00
5 2104.509 SALVAGE & REINSTAll MAilBOX EACH 3 $ 40.00 $ 120.00
6 2105.511 COMMON CHANNEL EXCAVATION CUYD 150 $ 6.00 $ 900.00
7 2105.521 COMMON BORROW TON 0 $ 18.00 $
8 2105.525 TOPSOil BORROW CUYD 30 $ 24.00 $ 720.00
9 2451.602 GRANULAR FOUNDATION MATERIAL CUYD 5 $ 22.00 $ 110.00
10 2501.515 SALVAGE AND REINSTAll 30" RCP APRON WITH TRASH GUARD EACH 1 $ 800.00 $ 800.00
11 2503.541 30" RC PIPE SEWER Cl V DESIGN 3006 (STORM) LlN FT 20 $ 67.00 $ 1,34000
11 0 30" RC PIPE SEWER Cl V 7-1/2 DEGREE BEND (STORM) EACH 2 $ 425.00 $ 850.00
12 2503.602 CONNECT TO EXISTING STORM SEWER, PIPE EACH 1 $ 500.00 $ 500.00
12 2504.602 ADJUST VALVE BOX EACH 1 $ 250.00 $ 250.00
13 2511.501 RANDOM RIPRAP Cl IV CUYD 7 $ 90.00 $ 630.00
14 0 CONST DRAINAGE STRUCTURE DES 54-4020 (INCl.CASTINGS) EACH 0 $ 2,400.00 $
15 2512.602 SALVAGE AND REINSTAll ARTICULATED CONCRETE MATTRESS EACH 1 $ 1,00000 $ 1,000.00
16 2574.505 SODDING TYPE lAWN SOYD 50 $ 2.15 $ 107.50
17 2575.505 SEEDING ACRE 0.5 $ 1,650.00 $ 825.00
18 2575.505 SEED MIXTURE ?? (WETLAND MIX) lB 10 $ 120.00 $ 1,200.00
19 2575.505 RAPID STABiliZATION METHOD 1 SOYD 20 $ 1.00 $ 20.00
20 2575.511 MULCH MATERIAL TYPE I TON 0.7 $ 500.00 $ 350.00
21 2575.523 SEED MIX 260CT, FERTiliZER 22-0-10 (NPK), AND TYPE 1 MULCH SOYD 50 $ 1.00 $ 50.00
22 2575.523 CATEGORY 3 EROSION CONTROL BLANKET SOYD 300 $ 2.00 $ 600.00
23 2575.523 CATEGORY 4 EROSION CONTROL BLANKET SOYD 40 $ 4.50 $ 180.00
24 0 WETLAND MITIGATION SO FT 0 $ 0.98 $
Contingency Items
1 2104.501 REMOVE CONCRETE CURB AND GUTTER LlN FT 0 $ 5.00 $
2 2104.513 SAWING BITUMINOUS PAVEMENT (FUll DEPTH) LlN FT 0 $ 3.50 $
3 2331.508 TYPE 41 A BITUMINOUS WEAR COURSE TON 0 $ 36.00 $
4 2331.521 BITUMINOUS DRIVEWAY RESTORATION SOYD 0 $ 15.00 $
5 2531.501 CONCRETE CURB AND GUTTER REPlACEMENT- B618 LlN FT 0 $ 20.00 $
TOTAL $ 12,724.50
ENG EST OP3A 7/27/2007
5A
EXHIBIT 5: ENGINEERS ESTIMATE
CITY OF PRIOR LAKE
2007 FISH POINT PARK OUTLET IMPROVMENTS - OPTION 38
2007 FISH POINT PARK OUTLET IMPROVMENTS
ITEM# SPEC. REF DESCRIPTION UNIT QTY UNIT PRICE TOTAL PRICE
1 2021.501 MOBILIZATION LUMP SUM 1 $ 300.00 $ 300.00
2 2101.502 CLEAR AND GRUB (TREE >6") TREE 12 $ 150.00 $ 1,800.00
3 2104.501 REMOVE EXISTING SEWER PIPE (STORM) L1N FT 8 $ 9.00 $ 72.00
4 0 REMOVE RETAINING WALL L1N FT 120 $ 9.00 $ 1,080.00
5 2104.509 SALVAGE & REINSTALL MAILBOX EACH 3 $ 40.00 $ 120.00
6 2105.511 COMMON CHANNEL EXCAVATION CUYD 80 $ 6.00 $ 480.00
7 2105.521 COMMON BORROW TON 110 $ 18.00 $ 1,980.00
8 2105.525 TOPSOIL BORROW CUYD 40 $ 24.00 $ 960.00
9 2451.602 GRANULAR FOUNDATION MATERIAL CUYD 18 $ 22.00 $ 396.00
10 2501.515 SALVAGE AND REINSTALL 30" RCP APRON WITH TRASH GUARD EACH 1 $ 800.00 $ 800.00
11 2503.541 30" RC PIPE SEWER CL V DESIGN 3006 (STORM) UN FT 75 $ 67.00 $ 5,025.00
11 0 30" RC PIPE SEWER CL V 7-1/2 DEGREE BEND (STORM) EACH 2 $ 425.00 $ 850.00
12 2503.602 CONNECT TO EXISTING STORM SEWER, PIPE EACH 1 $ 500.00 $ 500.00
12 2504.602 ADJUST VALVE BOX EACH 1 $ 250.00 $ 250.00
13 2511.501 RANDOM RIPRAP CL IV CUYD 7 $ 90.00 $ 630.00
14 0 CONST DRAINAGE STRUCTURE DES 54-4020 (INCL.CASTINGS) EACH 1 $ 2,400.00 $ 2,400.00
15 2512.602 SALVAGE AND REINSTALL ARTICULATED CONCRETE MATTRESS EACH 1 $ 1,000.00 $ 1,000.00
16 2574.505 SODDING TYPE LAWN SQYD 50 $ 2.15 $ 107.50
17 2575.505 SEEDING ACRE 0.5 $ 1,650.00 $ 825.00
18 2575.505 SEED MIXTURE ?? (WETLAND MIX) LB 8 $ 120.00 $ 960.00
19 2575.505 RAPID STABILIZATION METHOD 1 SQYD 20 $ 1.00 $ 20.00
20 2575.511 MULCH MATERIAL TYPE I TON 0.7 $ 500.00 $ 350.00
21 2575.523 SEED MIX 260CT, FERTILIZER 22-0-10 (NPK), AND TYPE 1 MULCH SQYD 50 $ 1.00 $ 50.00
22 2575.523 CATEGORY 3 EROSION CONTROL BLANKET SQYD 300 $ 2.00 $ 600.00
23 2575.523 CATEGORY 4 EROSION CONTROL BLANKET SQYD 40 $ 4.50 $ 180.00
24 0 WETLAND MITIGATION SQ FT 2500 $ 0.98 $ 2,450.00
Contingency Items
1 2104.501 REMOVE CONCRETE CURB AND GUTTER L1N FT 0 $ 5.00 $
2 2104.513 SAWING BITUMINOUS PAVEMENT (FULL DEPTH) LIN FT 0 $ 3.50 $
3 2331.508 TYPE 41 A BITUMINOUS WEAR COURSE TON 0 $ 36.00 $
4 2331.521 BITUMINOUS DRIVEWAY RESTORATION SQYD 0 $ 15.00 $
5 2531.501 CONCRETE CURB AND GUTTER REPLACEMENT- B618 L1N FT 0 $ 20.00 $
TOTAL $ 24,185.50
ENG EST OP3B 7/27/2007
5A