HomeMy WebLinkAbout5.b. Accept Feasibility Report, Hawkins Pond Drainage, City Project #176DATE: OCTOBER 5, 1987
TO: CITY COUNCIL
C/O STEVE JILK, CITY ADMINISTRATOR
FROM: RICH HEFTI, CITY ENGINEER/PUBLIC WORKS DIRECTOR
RE: ACCEPT SECTION 30 ENGINEERING STUDY ON DRAINAGE
ACCEPT FEASIBILITY REPORT, PROJECT 176, HAWKINS POND DRAINAGE
Attached are copies of the following reports that Council authorized at their
September 1, 1987 meeting on the following:
I. Engineering Report for Storm Sewer Improvements in Section 30
2. Report on Drainage Improvements for Sections 19 & 30, City Project #176
The Engineering Report does indicate the feasibility of draining the entire
Section 30 into Hawkins Pond. The Project #176 Report maintains the feasibility
of the concept for the Hawkins Pond area to provide the ultimate drainage to
Section 30, and surrounding area as noted within the report. However, the scope
of the Project #176 Report increase some because of more accurate information
obtained from the engineer report for Section 30 storm sewer drainage. The Pond
volume increased over what was originally anticipated and the easement.estimates
were also increased based on recent experience.
Though it is evident that Project #176 is necessary and feasible to provide a
ponding area for storm water run-off from developed and potential developable
surrounding property rather than to continue using property that we do not own to
provide the same service. Also, it is evident from the Engineer Report on
Section 30 drainage that we need to construct storm sewer to relieve some trouble
areas and retrieve the best use of other areas by transporting the storm water to
the Project #176 ponding area. The Project #176 feasibility report recommends,
and I agree, that the Section 30 storm sewer engineering study be implemented
with the Project #176 drainage basin construction. In order to accomplish that,
we need to expand the "Engineering Report for Storm Sewer Improvements in Section
30" to a full-fledged feasibility report.
I would recommend that Council receive both the report and the feasibility study
and authorize a feasibility study for the "Storm Sewer Improvements in Section 30
Project #177". Upon the completion of the feasibility study for Project #177
Council could set a Public Hearing date to consider storm sewer improvements for
both projects at the same time.
I will be available at the October 6, 1987 Council meeting if Council has
questions regarding this matter.
REPORT
ON
DRAINAGE IMPROVEMENTS
FOR
SECTIONS 19 & 30
CITY PROJECT NO. 176
ROSEMOUNT, MINNESOTA
Revised: September, 1987
SEH FILE NO: 88026
(Revision of Previous Report Supplement - Files: 81.027 & 81030)
I hereby certify that this report was prepared
by me or under my direct supervision and that I
am a duly Registered Professional Engineer under
the laws of the State of Minnesoto.
DATE: October 2. 1987 REG. NO. 12691
REVIEWED BY:
DATE: 0 g --,
INDEX
LETTER OF TRANSMITTAL
PAGE NO.
AUTHORIZATION
- 1
SCOPE
- 1 -
DATA AVAILABLE
- 1 _
DESIGN CONSIDERATIONS
- 1 -
TABLE A
Generated Storm Water Runoff Volumes
-_3 -
PROPOSED IMPROVEMENTS
- 3 -
EASEMENTS
_ 5 _
CONSTRUCTION TIMING
_ 5 -
COST ESTIMATES
- 5 -
PROJECT DISTRICT
_ ( _
CONCLUSIONS
- 8
APPENDIX:
Estimate of Cost
Drawing #1 - Assessment District Boundry
Drawing #2 - Hawkins Pond Drainage Area
AW
AMW
AAASEH
ENCINEERS 2ARCNITECTS8PLANNERS 222 EAST LITTLE CANADA ROAD, ST PAUL, MINNESOTA 55117 612 484-0272
October 2, 1987 RE: ROSEMOUNT, MINNESOTA
HAWKINS POND DRAINAGE IMP.
SEH FILE NO: 88026
Honorable Mayor and Council
City of Rosemount
2875 145th Street West
Rosemount, MN 55068
Attn: Rich Hefti, City Engineer
Gentlemen:
In accordance with your authorization we have revised our
previous report on drainage improvements in Sectins 19 & 30
initially presented in December, 1981. This report specifically
discusses improvements to Hawkins Pond as well as associated
construction. The report includes conclusions, cost estimates
and drawings for your review.
We would be available to review this report in detail with you
upon request:
Respectfully submitted,
SHORT-ELLIOTT-HENDRICKSON, INC.
Steve Campbell
SDC/cih
Enclosure
SHORT ELLIOTT ST. PAUL, CHIPPEWA FALLS,
HENDRICKSON INC. MINNESOTA WISCONSIN
I
AUTHORIZATION
At the Rosemount City Council meeting of September 1, 1987, the
Council authorized the preparation of a revised drainage study
for portions of Sections 19 & 30. The report was authorized to
address existing drainage flows from the developed area south of
145th Street West and the potential for additional flows from
future development in the area.
SCOPE
This report was originally presented in December, 1981. Since
then, the study area has been expanded to include additional
areas in Section 30 to accommodate long range planning. The
purpose is to study,' make recommendations and provide cost
estimates for the construction of drainage facilities within the
study area as well as to assist in the future planning of
drainage and land development for this area.
DATA
AVAILABLE
Information and materials used in the preparation of this report
include:
1.
Report on
Drainage Improvements for Sections 19 & 30
(December, 1981).
2.
Feasibility
Report for Highpointe First Addition Utilities
and Shannon
Parkway Grading and Utilities (May 19, 1981).
3.
Topographic
maps of Section 30.
4.
Preliminary
utility plans for Highpointe First Addition.
5.
Preliminary
grading and utility plans for Shannon Parkway.
6.
Grading and
drainage plans for Country Hills 1st and 2nd
Additions.
7.
Engineering
Report for Storm Sewer Improvements in Section
30.
DESIGN CONSIDERATIONS
The study area consists of three
which have been topographically
shown on Drawing No. 3.
internal drainage districts
divided into subdistricts as
The subdistricts are listed below with their respective areas:
SUBDISTRICT AREA
B-1 12 ACRES
B-2 188 ACRES
B-3 24 ACRES
B-4 11 ACRES
DISTRICT B TOTAL 235 ACRES
C 40 ACRES
D-1 38 ACRES
D-2 32 ACRES
DISTRICT D TOTAL 70 ACRES
For the purpose of this report a 100 year frequency, 24 hour
duration design storm has been used to determine the runoff
volumes for ponding. A 10 year frequency storm was used to size
the proposed storm sewer. This is consistent with the past
design practices within the city.
On the following page, Table A shows the runoff generated from
the subdistricts from the design storm for existing and future
conditions. Existing conditions are defined as those which exist
today. Future conditions are those which will ultimately exist
after the complete development of the entire study area. For the
purposes of this report all areas not currently proposed for -
development have been considered to be ultimately residential.
- 2 -
TABLE A
GENERATED STORM WATER RUNOFF VOLUMES (IN ACRE-FEET)
ULTIMATE
SUBDISTRICT
LAND USE
EXISTING
PROPOSED
B-1
RESIDENTIAL
1.9
3.0
B-2
RESIDENTIAL
29.8
47.0
B-3
RESIDENTIAL
6.0
6.0
B-4
RESIDENTIAL
2.8
2.8
DISTRICT
B TOTALS
40.5
58.8
C
RESIDENTIAL/
INDUSTRIAL PARK
8.0
10.0
D-1
RESIDENTIAL
9.5
9.5
D-2
RESIDENTIAL
8.0
8.0
DISTRICT
D TOTALS
17.5
17.5
TOTAL
66.0
86.3
Although not all of the subdistricts currently drain directly to
the proposed ponding area, the pond should be sized to accomodate
all runoff within the study area as discussed in the Section 30
Engineering Report.
PROPOSED IMPROVEMENTS
The drainage facilities proposed as a part of this improvement
are shown on Drawing No. 3. These facilities consist of the
creation of a storm water retention pond (Pond 30-P1) and a
drainage channel.
Pond 30-P1 is proposed in an existing low area between Country
Hills Addition and 145th Street and lies west of Shannon Parkway.
An existing small pond surrounded by trees is located within the
proposed Pond. The stage/storage relationship for Pond 30-P1 is
as follows:
- 3 -
STAGE (ELEVATION) STORAGE (ACRE -FEST)
910 0
912 5
914 12
916 19
918 28
920 37
922 48
924 59
926 72
928 86
Construction of a drainage channel is proposed as shown to the east
from the pond to transport runoff from the Shannon Parkway storm
sewer system across private property.
The construction of Pond 30-P1 will provide for the abandonment of
the existing pond in Sub -district B-4. This pond will be drained by
the storm sewer in proposed Shannon Parkway.
The construction of Pond 30-P1 will also provide for the abandonment
of the existing pond in District C. This existing pond can be
drained by the construction of a storm sewer to transport flows from
District C to the proposed Pond 30 -PI. A detailed discussion of
this storm sewer is provided in the Section 30 Storm Sewer Report.
District D includes two minor retention areas located on either side
of Dodd Boulevard in Twin Puddles Park. These areas will ultimately
be abandoned when storm sewer is constructed to transport runoff
from District D to the proposed Pond 30-P1. A detailed discussion
of this storm sewer is also provided in the previously mentioned
engineering report.
The drainage swales, which are proposed herein, will generally have
a depth of 3 to 4 feet with a flat bottom approximately 5 to 10 feet
wide. The side slopes will be relatively flat for easy maintenance.
These swales will normally remain dry except during and temporarily
after storm events.
All areas disturbed in the construction of the ponding areas and
swales are proposed to be restored to prevent erosion once they
become operational.
- 4 -
EASEMENTS
The ponding areas, storm sewer, and drainage swales proposed
herein will serve all properties within their respective drainage
districts and should be considered as City drainage facilities.
It is therefore recommended that the City secure easements from
the property owners, for the construction, operation, and
maintenance of these facilities. In the case of the ponding
areas, the easements should extend to the maximum ponding stage,
plus an additional 50+ feet around the perimeter as shown in the
drawings to serve as a buffer. In the case of the storm sewer
and drainage swales, a 30 foot wide drainage easement should be
obtained concurrent with the alignment of the facility.
CONSTRUCTION TIMING
The facilities proposed herein should be operational at the time
of completion of the Shannon Parkway storm sewer construction.
It is anticipated at this time that the Shannon Parkway utilities
will be completed during the 1988 construction season.
Therefore, it is recommended that these improvements be
constructed under separate contract in the spring of 1988 so as
to assure the establishment of adequate ground cover on these
facilities prior to the completion of the storm sewer
construction.
COST ESTIMATES
Detailed estimated costs of the improvements proposed herein can
be found in the appendix of this report. It should be noted that
this estimate assumes that excavated materials can be disposed of
in adjacent areas. These estimates have been based on projected
unit prices for the 1988 construction season and include a 10
percent allowance for contingencies and other indeterminate costs
plus an additional allowance for engineering, administration, and
other overhead costs. This estimate includes the cost of
easements for the rights of operation of these facilities. The
total estimated cost of the proposed construction is $300,000.
5
PROJECT DISTRICT
The following properties are located within the project district.
Unplatted Lands
NW 1/4 - Section 30
010-30
010-35
010-36
010-38
010-39
010-40
010-41
010-42
010-43
010-44
010-45
011-25
013-37
014-37
020-30
020-35
020-40
020-44
NE 1/4 - Section 30
010-12
SE 1/4 Section 30
012-80
013-80
014-80
SW 1/4 - Section 30
001-55
002-55
003-55
004-55
010-52
010-54
020-52
020-54
030-52
031-54
040-52
050-52
060-52
061-52
080-52
090-52
100-52
110-52
Platted Property
Broback
Addition
Blk
1
Lot
1
Blk
2
Lots
1-3
Blk
3
Lots
1-11
Blk
4
Lots
1-7
Broback
2nd
Addition
Blk
l
Lots
1-3
Blk
2
Lots
1-4
Blk
3
Lots
1-10
Blk
4
Lots
1-14
Blk
5
Lots
1-7
Outlot 1
Broback
3rd
Addition
Blk
1
Lots
1-11
Blk
2
Lots
1-11
Blk
3
Lots
1-17
Blk
4
Lots
1-8
Broback
4th
Addition
Blk
1
Lots
1-17
Blk
2
Lots
1-13
Broback
5th
Addition
Blk
1
Lots
1-13
Blk
2
Lots
1-18
Blk
3
Lots
1-12
Broback
6th
Addition
Blk
1
Lots
1-8
Blk
2
Lots
1-13
Broback
7th
Addition
Blk
1
Lots
-1-6
Blk
2
Lots
1-15
Blk
3
Lot
1
Blk
4
Lots
1-2
Broback
8th
Addition
Blk
1
Lots
1-5
Blk
2
Lots
1-7
Outlot A
Broback
11th
Addition
Blk
1
Lots
1-8
Blk
2
Lots
1-3
Blk
3
Lots
1-5
Broback
12th
Addition
Blk
1
Lots
1-19
Outlot A
Broback
Industrial
Park
Blk
1
Lots
1-5
Blk
2
Lots
1-5
Outlot B
Evergreen Acres
Blk
l
Lots
1-3
Shannon
Park
1st Addition
Blk
1
Lots
1-4
7
CONCLUSIONS
As a result of the investigation and study associated with this
report, it is concluded that:
1. The construction of the proposed drainage facilities
described herein is feasible.
2. The ponding areas and drainage swales proposed herein should
be considered as city drainage facilities.
3. The facilities proposed herein should be operational at the
time of completion of the Shannon Parkway storm sewer
construction.
4. The total estimated cost of the proposed improvements is
$300,000.
5. Consideration should be given to combining the provisions of
this report and the Section 30 Storm Sewer Report into one
improvement nroieet_
ESTIMATE OF COST
HAWKINS POND DRAINAGE IMPROVEMENTS
SECTION 30
ROSEMOUNT, MINNESOTA
UNIT
DESCRIPTION
UNIT
QUANTITY
PRICE
AMOUNT
Pond Excavation
C.Y.
100,000
1.50
$150,000
Channel Excavation
C.Y.
900
3.00
2,700
Salvaged Topsoil
C.Y.
5,400
4.00
21,600
42" RC Pipe Sewer
L.F.
125
100.00
12,500-
42" RC Apron
EACH
2
1,500.00
3,000
Seeding
ACRE
10
200.00
2,000
Seed
LB.
400
4.00
1,600
Mulch
TON
11
400.00
4,400
Disc Anchoring
ACRE
10
100.00
1,000
SUBTOTAL
$198,800
_ PLUS 10$ CONTINGENCIES
21,200
ESTIMATED CONSTRUCTION COST.
$220,000
PLUS 15% ENGINEERING, ADMIN.
& OVERHEAD
30,000
EASEMENTS
50,000
TOTAL ESTIMATED COST
$300,000
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ENCIN CHITECTS 0 PLANNERS ASSESSMENT DISTRICT 60UNDRY oRG.'No