HomeMy WebLinkAbout1995-12-23 BRAA Ltr to OPH Re Annexation Area Surface Water Mgmt PlanBonestroo
a:: M Rosene
Anderlik
Associates
Engineers Architects
December 23, 1995
Honorable Mayor Council Members
City of Oak Park Heights
14168 57th Street North
Stillwater MN 55082 -2007
Otto G. Bonestroo, P.E.
Robert W. Rosene, P.E.*
Joseph C. Anderlfk, P.E.
Marvin L; Sorvala, P.E.
Richard E. Turner, P.E.
Glenn R. Cook, P.E.
Thomas E. Noyes, P.E.
Robert G. Schunicht, P.E.
Susan M. Eberl €n.
Senior Consultant
Re: Annexation Area Surface Water Management Plan
Our File No. 55121
Dear Mayor Council Members:
Bonestroo, Rosene, Anderllk and Associates, Inc. Is ,an Affirmative Action /Equal Opportunity Employer
Howard A. Sanford, P.E.
Keith A. Gorr
Robert R, Pfe
Richard W. Foster, r.t.
David O. Loskota, P.E.
Robert C. Russek, A.I.A.
Jerry A. Bourdon,•P.E,
Mark A. Hanson, P.E.
Michael T, Rautrnann, P.E.
Ted K. Field, P.E.
Thomas R. Anderson, A.I.A.
James R. Rosenmerkel, P.E.
Donald C. Burgardt, P.E.
Thomas A Syfko, P.E.
Frederic J. Stenborg, P.E,
Ismael Martinez, P.E.
Michael P. Rau, P.E.
Thomas W. Peterson, P,E.
Michael C. Lynch, P.E.
James R. Maland, P.E.
Jerry D. Pertzsch, P.E.
Scott J. Arganek; P.E.
Kenneth P. Anderson, P.E.
Mark R. Rolls, P.E.
Mark A. Selp, P,E,
Gary W. Mor €en, P.E,
Paul J. Gannon, ALA.
Daniel J. Edgerton, P.E.
A. Rick Schmidt, P.E.
Dale A. Grove, P.E.
Philip J. Caswell, .P.E,
Mark D. Wal €Is, P.E.
Miles B. Jensen, P.E.
L. Phillip Gravel, •P.E.
Karen L. Wiemeri, P.E.
Gary D. Krlstof€tz, P.E.
Bran K. Gage, P.E. I
F. Todd Foster, P.E.
Keith R, Yapp, P.E.
Douglas J. Benoit, P,E,
Shawn D. Gustafson, P.E.
Cecil €o Olivier, P.E.
Kent J. Wagner, P.E.
Paul G. Heuer, P.E.
John P. Gorder, P.E.
Dan D. Boyum, P.E,
Jeffrey J.. Ehleringer, P.E.
Joseph R. Rhein, P.E.
Lee M. Mann, P.E.
Charles A. Erickson
Leo M. Pawelsky
Harlan M. Olson
Agnes M. Ring
James F. Engelhardt
Submitted herewith is the Surface Water Management Plan for the portion of oak. Park Heights west
of Oakgreen Avenue, hereinafter referred to as the "annexation area." The information presented in
this report is intended to provide a basis for the construction of a cost effective trunk stormwater
system for this area.
1. Introduction
This report presents a Surface Water Management Plan for the annexation area of oak. Park Heights.
This area, shown in Figure No. 1, is defined by Oakgreen Avenue on the east, State Highway 36 on
the north, State Highway 5 on the west, and the natural drainage boundaries along the city limits on
the south.
The report contains a discussion of the hydrologic and water quality modeling, including assumptions
about design storms and land use. It also presents cost estimates to pay for the proposed facilities.
The proposed storm sewer system is presented in Figure No. 1, and detailed design information is
contained in the report tables,
II. System Analysis
Physical Environment and Land Use
The annexation area is at the headwaters of three watersheds. The northern portion of the area, in
the Browns Creek Watershed, flows north under Highway 36. The southeastern portion of the area,
in the Middle St. Croix Watershed, flows northeast and southeast. The southwestern portion of the
area, in the Valley Branch Watershed, flows south to Cloverdale Lake,
2335 West Highway 36 if St. Paul, MN 55113 m 612 636-4600
The area is gently rolling, with a number of landlocked depressions. The soils in the e area are
generally well drained. Many of the depressions contain ponds and wetlands. Land cover
P consists of agricultural area, open space, forested area, commercial development along Highway P g g y 3 6, the
Stillwater High School, and single-family residential area. Long-term land use was assumed d to be
commercial north of 58th Street North, and single family residential lus the high school south
P of
58th Street North.
Hydrologic Analysis
Hydrologic modeling was performed to design the trunk storm sewer system. The trunk system y y is
defined as the stormwater detention ponds plus the storm sewers necessary to connect them with the
y
various outlets from the annexation area. The detention ponds were designed to store and release
the runoff from a 100 -year storm event without flooding of adjacent buildings.
Both the 5.9 -inch, 24 -hour rainfall. and the 7.2 -inch, 10-day runoff were investigated, with g w th the more
critical high water level used for each pond. In the majority of the ponds, the 24 -hour rainfall event
proved to be more critical. We recommend a minimum 2 -foot freeboard from the on
p d high water
level to the lowest opening in adjacent buildings.
The hydrologic modeling software HydroCAD was used for the modelin g Drainage e areas were
determined from 2 -foot contour maps. Pond normal water levels were set to match existing
conditions to the greatest extent possible. As -built or proposed development plans were used where
appropriate. The model was used to size pond outlet facilities and compute pond high water levels,
storage volumes, and peak outflows.
The proposed trunk storm sewer system is presented in Figure No. 1. Drainage areas are given
in
g g
Table 1. Detention pond data are presented in Table 2.
Water Quality Analysis
A water quality analysis was performed to ensure that the stormwater leaving the annexation area will
be of good quality. A goal of less than 200 parts per billion (ppb) of phosphorus in the stormwater
P P
leaving the area was selected as a design criterion, as this corresponds to typ ical natural
concentrations.
Because a number of the existing depressions and wetlands have ponded water, these were
incorporated into the water quality system. In other areas with less capacity for P ollutant removal,
water quality ponds are proposed to be excavated.
The proposed water quality ponding system is shown in Figure No. 1 and is conceptual in nature and
not necessarily to scale. Detailed information on the water quality ponds is presented in Table 3.
Ponds 11, 21, 31, and 42, representing flows out of the study area, all have outflow hos horus
P P
concentrations less than 200 ppb.
Four ponds (13a, 13b, 15a, and 32a) are proposed to be excavated strictly for water ualit purposes.
yp oses. P
Four ponds (15, 22, 23, and 44) are proposed to be excavated for both water uantit and quality
q q y
Oak Park Heights Annexation Area Swface Water Management Plan
purposes. The remainder of the ponds have already been designed or constructed (11, 12, 21, 42,
and 43) or rely primarily on existing, natural contours. A grading plan has been submitted for Pond
15a, but this is for a small pond to handle local runoff only. This Surface Water Management Plan
calls for Pond 15a to be expanded in the future to handle more regional flows.
The 12 -inch outlet from Pond 31 has been designed to maximize storage and water quality treatment.
The contour maps indicate a number of trees in this area. Without further field survey information,
it is difficult to estimate the elevations of the lowest trees. If necessary, it would be possible to lower
the normal water level in Pond 31 from the proposed 903 to about 901 to prevent flooding of
adjacent trees. This reduction in normal water level would not have a significant effect on the water
quality leaving the pond.
III. Cost Estimates
Cost estimates for the proposed facilities were developed and are presented in Table 4. The estimated
total project cost for the storm sewer system is $894,200, including engineering, administration,
interest during construction, and contingencies. Land and easement acquisition costs are not
included. The costs are based on 1995 construction costs and can be related to an ENR Index of
Construction Costs of 5,432 (June 1995). Future changes in the index are expected to reflect fairly
accurately cost changes in the proposed facilities.
No Cost Allocation
Table No. 1 identifies 685 acres of land within the study area of which 260 acres has been platted
and/or developed and assigned area charges. After subtracting land consumed in collector street and
highway right of-way and deducting undevelopable land consisting of steep slopes, wetlands and
ponds, the resulting assessable land is approximately 320 acres broken down as follows:
Low Density 230 acres
High Density 40 acres
Commercial- Industrial 50 acres
If the existing stoma. sewer area charges are applied to the assessable land area, the following revenue
will be generated:
Low Density 230 ac x 2,405.00 /ac $553,150.00
High Density 40 ac x 3,935.00/ac 157,400.00
Comm. -Ind. 50 ac x 4,650.001ac 232500.00
Total Revenue $943,050.00
Based on this analysis, the charges currently in place should fund the trunk storm sewer and ponding
requirements defined for the study area.
The above analysis does not provide for any costs for land acquisition. Ponding areas are generally
dedicated as a part of the development process because they are normally located in or around
existing wetlands. However, because there has been some objection to dedicating land for regional
Oak Park Heights Annexation Area Surface Water Management Plan
ponding, it is suggested that the following additional charge for storm water ponding be initiated in
is P g
the event land s not dedicated without cost.
V. Summary
ary
This report presents a proposed trunk stormwater system for the annexation area of Oak. Park
Heights. The system, shown in Figure No. 1, includes storm sewers and stormwater ponds for both
flood control and water quality purposes. Tables 1 to 3 .present design information on the system.
Cost estimates are presented in Table 4. The total estimated cost of the proposed system is $894,200.
VI. Recommendations
Land Use Ponding Charge
Low Density $1,600.00/acre
High Density $2,400.00/acre
Commercial- Industrial $3 ,200.00/acre
It is recommended that the City adopt this Surface Water Management Plan and use it for the design
and implementation of surface water drainage facilities to serve the study area west of Oakgreen
Avenue. It is further recommended that the current system of area charges be continued and that an
additional charge be initiated to encourage land dedication for ponding and/or to secure funding for
land acquisition.
Respectfully submitted,
B ONI S1 1 1 0, ROSENE, ANDERLIK ASSOCIATES, INC.
Daniel J. Bdg rto n,
1 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 innesota
f
Josep F C derlik, P.E.
Date: December 23, 1995
Reg, No. 6971
Oak Park Heights Annexation Area Surface Water Management Plan
Area
-rr� I�eszgnatian
Drainage
Area
(acres)
.�wp�� wpw ra �rr+inmarmea
111
59
112
20
121
29
131
33
132
26
141
64
151
19
152
19
211
8
221
23
231
8
241
13
311
55
321
63
331
32
341
11
351
18
421
81
431
26
441
45
451
19
461
14
TABLE 1. DRAINAGE AREAS.
Pond
Tributary Area (acres)
Normal
Water
Level
High
Water
Level
Storage
Volume
Above NWL
(ac -ft)
Pond Peak
Outflow
(cfs)
Direct
Ponded
Total
11
79
190
269
917.0
9215
29.4
35.5
12
29
0
29
933.2
936.8
4.6
5.5
13
59
0
59
927.0
930.0
12.9
2.7
14
64.
0
64
926.0
930.8
11.6
5.5
15
38
29
67
918.0
924.1
6.4
54.3
21
8
44
52
915.6
918.6
0.5
21.2
22
23
21
44
928.0
933.3
4.2
6.4
23
8
13
21
931.0
935.4
2.0
3.9
24
13
0
13
932.9
935.9
1.7
4.2
31
55
124
179
903.0
908.2
45.8
4.3
32
63
0
63
911.0
913.3
9.4
17.1
33
32
29
61
904.5
908.3
13.8
2.9
34
11
18
29
912.0
918.1
1.7
6.8
35
18
0
18
926.0
928.5
2.6
5.4
42
81
104
185
915.0
923.5
33.5
12.0
43
26
45
71
924.0
929.1
4.2
45.5
44
45
0
45
931.0
934.9
13.2
7.2
45
19
14
33
934.0
935.2
4.5
3.1
46
14
0
14
935.0
936.0
2.6
1.8
TABLE 2. DETENTION POND DATA.
Pond
Direct
Tributary
Area
(acres)
Normal
Water
Level
Pond Area
NWT
(acres)
Wet
Volume
(ac --ft)
Outflow
P -conc.
(ppb)
Total
Efficiency
11 (3-cell)
59.0
917.0
2.82
10.3
192
68
12
29.0
9312
1.09
2.0
232
.51
13(2 -cell)
34.5
927,0
2.45
t 3
179
64
13a
24.5
929,0
0.50
207
59
13b
26.0
945.0
0.50
184
59
14 (3 -cell)
64.0
926.0
0.97
164
64
15
19.0
918.0
1.00
228
62
15a
19.0
937.5
070
238
60
21
8.0
915.6
0.20
199
58
22
23.0
928.0
0.48
196
59
23
21.0
931.0
0.24
274
42
31
55.0
903.0
6.00
12.0
143
66
32
15.6
911.0
3.90
6.2
156
67
32a
47.4
911.0
0.70
2.9
206
57
33
32.0
904.5
2.20
9.5
146
69
34
29.0
912.0
0.23
0.8
255
46
42
81.0
915.0
2.40
15.8
158
68
43
26.0
924,0
0,62
2.0
261
56
44
45.0
931.0
1.70
6.6
239
60
45
19.0
934.0
3.50
L8
152
66
46
14.0
935.0
2.90
14.5
135
70
TABLE 3. WATER QUALITY POND DATA.
Total
Cost
00C*
008'LZ
00r6Z
1. 008'19
008'6E
000'17Z
006‘g9
OOL`L
IL 005' I Z
34,200
IF 00V5Z
000'81
00Z`17:
008'ZZ
0017' I E
00Z
009‘ZE
24,300 I
00Z`1768$
Other
Cost 4/
006'171
00E%
1 0006
20,600
00E`E I
000'8
000'Z
r 006'51
oozcL
11,400
0017'8
000'9
00
009'L
00g'0I
00I'EOI
10,900
001'8
00E'86Z$
1SOD
mows
008'6Z
00g'8I
0017'61
00Z' I ti
005'9Z
16,000
006'£17
008'1E
00£17I
008'ZZ
008'91
000'ZI
22,800
00Z
0060Z
00I '90Z
00L' 1Z
00V9I
006'g6g$
isop
puod
000'17
000'6
oosLLT
005 LI
000'8
000'6
008`ZZ
00g'0I
00g‘E
00E'9E
00E`ZZ
005'6
005'6
005'6
000'ZI
005'6
005'6
00c`6
r 204,000
005'6
00g'6
00VZ517$
Outlet
Cost 3/
($/each)
000't7
000'6
005'6
00g'6
000'8
000'6
005'6
00g‘E
00g'6
00g'6
00g'6
005'6
005'6
005'6
005'6
00g'6
000'6
005'6
00g'6
Pond Unit
Cost 2/
($/CY)
057
OCZ
OCZ
05' 1 Z
i
i
Og'Z
ocz
1
Og:Z 1
Og•Z
OcZ
Og`Z
o
ocz
05'Z
Og'
OCZ
00'g
Og•Z
OCZ
Pond
Excavation
(CY)
1 00z:'
I ooz‘
00E' g
00V•17
0000 I
001
008'17
0
c
Q
000'6E
Ca
C7
isop
odid
00E'L
005'6
000'1
1 006'1
20,400 1
oos`c
00L'E
000‘z
OWL
00g'6
008'17
00E'ET
00E
Ca
00E' E I
00L'g
001'
0OCZ
00Z‘ZI
00L9
00C'Ef7I
Pipe Unit
Cost 11
($/ft)
0063
1 00'61
00•61
00
0061
00'LE
00'gZ
00
00'6I
00'61
0061
r 00
00'61
00'61
00•61
00`TZ
00
00
(1j)
14
odId
OgZ
00g
Og
OOT
00i7
00Z
001
08
0017
00g
OgZ
OOL
05Z
OOL
00E
009
001
Ot79 I
ocz I
NI
t7Z
Z I
Z I
1 11
Z I
OE
81
Z1
Z
Z1
T
17Z
Z I
Z1
Z I
g I
Z I
MOH
I I Puod
puod
Pond 13 1
1 u puo d
puod
T puod
I Z Puod
Pond 22
rPond 23
loPno
Pond 31
ZE Puod
[Pond 31
Pond 33
!Pond 34
Pond 43
I Pond 42
j7 jUOJ
TOTALS
I
W014
MOE
ET puodl
l[Pond 13a 1
liPond 13b 1
11Pond 14 1
pc pUOd
11Pond 22
IIPond 23
11Pond 24
puodl
ZE Puod
l[Pond 32a
EE puodi
IiPond 34
puodil
IIPond 44
l[Pond 45
917 Puol
czt
td
0
0
0
4
r 7;]
W
f'4
0
C7Q tC1
ct1
0 Cd
c5L
(1)
0
N
0
[l1
ta
Cl]
"0
0
0
04
1 tO cid
8 Yw
0
0 i.
G
0 3.
;4 v o
0 0
0 0
st
0 Q 1.-,
ti cl 0
ai ,...4 .H
49 7,,, go
8 h
C7 4 cl
yam t --1 h
E CI
0
0 !L]
r
rin
ri) Q
al 0 Q Q
0
C3 0 b4
cz 0 0
Q rn al
0 Ca-4
0 0
0 Q C
0
CCU
X
a
Q c
0 ii 03
G b
a a
TABLE 4. COST ESTIMATES.
N
M y
N i
I i di
g i i
px
p 0. tit gd
d w
1 e 8 1
a
111 P8
0 o o a" 1
E
LL
co
0 0)
4=
ai
O)
W c
C
e
0)
L
b'
id
a