HomeMy WebLinkAboutSWALLOW OFFICE BUILDING - PDP - 45-00 - REPORTS - DRAINAGE REPORTPROJECT:
Swallow Office
CONSTRUCTION SEQUENCE
COMPLETED BY: B. Strand
STANDARD FORM C
DATE: 21-Dec-00
Indicate by use of a bar line or symbols when erosion control measures will be installed. Major modifications to an
approved schedule may require submitting a new schedule for approval by the City Engineer.
MONTH
1
2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
1 10
1 11
1 12
Demolition
Grading
Wind Erosion Control:
Soil Roughing
Perimeter Barrier
Additional Barriers
Vegetative Methods
Soil Sealant
Other
Rainfall Erosion Control
Structural:
Sediment Trap/Basin
Inlet Filters
Straw Barriers
Silt Fence Barriers
Sand Bags
Bare Soil Preparation
Contour Furrows
Terracing
Asphalt/Concrete Paving
Other
Vegetative:
Permanent Seed Planting
Mulching/Sealant
Temporary Seed Planting
Sod Installation
Netting s/Mats/Blankets
Other
BUILDING CONSTRUCTION
STRUCTURES: INSTALLED BY:
VEGETATION/MULCHING CONTRACTOR:
DATE SUBMITTED:
CONTRACTOR
TO BE DETERMINED BY BID
APPROVED BY CITY ON:
MAINTAINED BY: DEVELOPER
911606er.xls,12/21 /00
SWALLOW OFFICE
EROSION CONTROL COST ESTIMATE
JOB NO. 9116.06
EROSION CONTROL MEASURES
COMPLETED BY: B. STRAND
ITEM
DESCRIPTION
UNITS
I UNIT COST
IQUANTITY
I TOTAL COST
1
TEMPORARY SEED & MULCH
ACRE
$ 655.00
0.07
$ 44.45
2
SILT FENCE
LF
$ 3.00
292
$ 876.00
3
GRAVEL CONSTRUCTION ENTRANCE
EACH
$ 500.00
1
$ 500.00
4
INLET PROTECTION
EACH
$ 250.00
0
$ -
5
STRAW BALES
LF
$ 3.25
15
$ 48.75
6.
SEDIMENT TRAP
EACH
$ 500.00
0
$ -
COST $ 1,469.20
CITY RESEEDING COST FOR TOTAL SITE AREA
ITEM
DESCRIPTION
UNITS
UNIT COST
IQUANTITY
I TOTAL COST
1
RESEED/MULCH
I ACRE
1 $ 615.001
0.3
1 $ 166.05
COST
$ 166.05
SECURITY DEPOSIT $ 1,469.20
REQUIRED EROSION CONTROL SECURITY DEPOSIT WITH FACTOR OF 150% $ 2,203.80
JR Engineering
2620 E. Prospect Rd., Ste. 190, Fort Collins, CO 80525
EFFECTIVENESS CALCULATIONS
PROJECT:
SWALLOW OFFICE
STANDARD FORM B
COMPLETED BY:
B. STRAND
DATE: -Dec-00
EROSION CONTROL
C-FACTOR
P-FACTOR
METHOD
VALUE
VALUE
COMMENT
BARE SOIL
1.00
1.00
SMOOTH CONDITION
ROUGHENED GROUND
1.00
0.90
ROADSIWALKS
0.01
1.00
GRAVEL FILTERS
1.00
0.80
PLACED AT INLETS
SILT FENCE
1.00
0.50
SEDIMENTTRAP
1.00
0.50
STRAW MULCH (S = 1-5%)
0.06
1.00
FROM TABLE 8B
STRAW BARRIERS
1.00
0.80
EFF = (1-C'P)•100
MAJOR
SUB
BASIN AREA
EROSION CONTROL METHODS
BASIN
BASIN
(Ac)
101
0.02
ROADS/WALKS
0.00 Ac.
ROUGHENED GR.
0.00 Ac.
STRAWIMULCH
0.02 Ac.
GRAVEL FILTER
NET C-FACTOR
0.06
NET P-FACTOR
0.80
EFF = (I -C!P)• 100 =
95.6%
102
0.25
ROADS/WALKS
0.14 Ac.
ROUGHENED GR.
0.06 Ac.
STRAW/MULCH
0.05 Ac.
GRAVEL FILTER
NET C-FACTOR
0.27
NET P-FACTOR
0.79
EFF = (I -C'P)' 100 =
78.5%
TOTAL AREA = 0.27 ac
TOTAL EFF = 79.8% (£ (basin area • eti) / total area
REQUIRED PS = 77.8%
Since 79.8% > 77.8%, the proposed plan is o.k.
911606er.xls
JR Engineering, Ltd.
2620 E. Prospect Rd., Ste. 190. Fort Collins, CO 80525
RAINFALL PERFORMANCE STANDARD EVALUATION
r
PROJECT: Swallow Office STANDARD FORM A
COMPLETED BY: B. Strand DATE: 21-Dec
DEVELOPED
ERODIBILITY
Asb
Lsb
Ssb
AI • Li
All • Si
Lb
Sb
PS
SUBBASIN(s)
ZONE
(AC)
(FT)
(•/.)
(Ft)
(%)
(%)
101
MODERATE
0.02
85
1.5
1.7
0.0
102
MODERATE
0.25
180
1.5
45.0
0.4
Total
1
0.27 1
1
46.70
0.41 1
173 1
1.5
77.8%
Asb = Sub -basin area
Lsb = Sub -basin flow path length
Ssb = Sub -basin slope
Lb = Average flow path length = sum(Ai Li)/sum(Ai)
Sb = Avenge slope = sum(Ai Si)/Sum (Ai)
PS is taken from Table 8-a (fable 5.1, Erosion Control Reference Manual) by interpolation.
An Erosion Control Plan will be developed to contain PS% of the rainfall sedimentation
that would normally flow off a bare ground site during a 10-year, or less, precipitation event
Erosion.xls
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HISTORIC
DRAINAGE SUMMARY
TABLE
Des Ign
Tributary
Area
C (10)
C (100)
to (10)
le (100)
Q(10)tot
QO 00)(at
Sub-basln
Point
ac
min
min
cfe
efs
1
H/
0.02
0.85
1.00
5.0
5.0
0.10
0.23
2
H2
O.25
0.68
1.00
5.0
5.0
1.08
2.51
20' 10' 0 20' AO'
SCALE: I' - 20'
PROJECT NAME: SWALLOW OFFICE
PROJECT NO: 39116.06
DATE: 12/21 /00
SHEET: 1 OF 1
JREngineering
2620 E. Prospect Rd., Suite 190
Fort Collins, Colorado 80525
Tel. (970) 491-9868
FAX (970) 491-9984
SUMMARY
DRAINAGE SUMMARY TABLE
Design
Point
Tributary
Sub -basin
Area
(ac)
c (10)
c (100)
tc (10)
(min)
tc (100)
(min)
Q(10)tot
(cfs)
Q(100)tot
(cfs)
Existing
1
H1
0.02
0.85
1.00
5.0
5.0
0.10
0.23
2
H2
O.25
0.88
1.00
5.0
5.0
1.08
2.51
Proposed
1
101
0.02
0.19
0.24
5.8
0.02
0.05
2
102
0.25
0.79
0.98
5.8
E5.6
0.91
2.48
Page 1
RATIONAL METHOD PEAK RUNOFF
(City of Fort Collins, 100-Yr Storm)
LOCATION:
Swallow Office
PROJECT NO:
9116.06
COMPUTATIONS BY:
B. Strand
DATE:
12/19/00
100 yr Storm, C1=
1.25
JR Engineering
2620 E. Prospect Rd., Ste. 190
Fort Collins, CO 80525
DIRECT RUNOFF
CARRY OVER
ITOTAL
REMARKS
Des.
Point
Area
Design.
A
(ac)
C Cf
tc
(min)
i
(inthr)
Q (100)
(cfs)
from
Design
Point
Q (100)
Ids)
a<100)tot
(ds)
Existing
1
H1
0.02
1.00
5.0
9.95
0.23
0.23
2
H2
O.25
1.00
5.0
9.95
2.51
2.51
Proposed
1
101
0.02
5.6
9.49
0.05
0.05
2
102
0.25
EO.24
5.0
9.95
2.48
2.48
Q=CiA
Q = peak discharge (cfs)
C = runoff coefficient
i = rainfall intensity (in/hr) from City of Fort Collins IDF curve (4/16199)
A = drainage area (acres) i = 64.682 / (10+ tCf A1v
9 1 1606flow.xls
RATIONAL METHOD PEAK RUNOFF
(City of Fort Collins, 10-Yr Storm)
LOCATION: Swallow Office
PROJECT NO: 9116.06
COMPUTATIONS BY: B. Strand
DATE: 12/19/00
10 yr storm, Cf = 1.00
JR Engineering
2620 E. Prospect Rd., Ste. 190
Fort Collins, CO 80525
DIRECT RUNOFF
CARRY OVER
TOTAL
REMARKS
Design
Point
Tributary
Sub -basin
A
(ac)
C Cf
It;
(min)
i
(in/hr)
Q (10)
(cfs)
from
Design
Point
Q (10)
(ds)
Q(10)t0t
(cfs)
Existing
1
H1
0.02
0.85
5.0
4.87
0.10
0.10
2
H2
O.25
0.88
5.0
4.87
1.08
1.08
Proposed
0.00
1
101
1 0.02
0.19
5.8
4.58
0.02
0.02
2
102
0.25
0.79
5.8
4.59
0.91
0.91
Q=CtC1A
Q = peak discharge (cfs)
C = runoff coefficient
Ct = frequency adjustment factor
i = rainfall intensity (in/hr) from City of Fort Collins IDF curve (4/16/99)
A = drainage area (acres) i = 41.44 f (10+ tCf i9"
911606fl w.xis
4
STANDARD FORM SF-2
TIME OF CONCENTRATION -100 YR
LOCATION: Swallow Office
PROJECT NO: 9116.06
comPi ITATIONS BY: B. Strand
DA'FL: 12/ 19/00
100-yr storm Cf = 1.25
JR Engineering
2620 E. Prospect Rd., Ste. 190
Fort Collins, CO 80525
SUB -BASIN
DATA
INITIAL (OVERLAND
TIME (ti)
TRAVEL TIME I GUTTER OR CHANNEL FLOW
(tt)
to CHECK
(URBANIZED BASIN)
FINAL
tc
REMARKS
DESIGN
PONIT
SUBBASIN(s)
(1)
Existing
Area
(ac)
(2)
C
(3)
C'Cf
Length
(ft)
(4)
Slope
I%)
(5)
ti
(min)
(6))
Length
(7)
Slope
(8))
n
Manning
Val,
((9)
l9)
It
(min)
(10)
tc =
It tt
It 1)
Total L
12ft)
(12)
tc=(Vl80)+10
(min)
(13)
(min)
(14)
1
2
H1
H2
0.02
O.25
0.85
0.08
1.00
1.00
100
150
2.6
2.6
1.4
1.7
0
0
1.0
1.0
0.016
0.016
2.0
2.0
0.001
0.00
1.4
1.7
100
150
10.6
10.8
5.0
5.0
Proposed
1
101
0.02
0.19
0.24
15
2.0
5.0
70
1.0
0.016
2.0
0.58
5.6
85
10.5
5.6
2
102
0.25
0.79
0.96
70
1.0
1.8
110
1.0
0.016
2.0
0.91
2.7
160
11.0
5.0
EQUATIONS:
tc=ti+tt
li=[1.87(1.1-CCf)L0.51/S1re
tt = L/Vel.
Velocity from Manning's Equation with R=0.1 (corresponds to Figure 3-3 of City of Fort Collins Design Manual)
final tc = minimum of ti + It and urbanized basin check
min. tc = 5 min. due to limits of IDF curves
911606flow.xls
STANDARD FORM SF-2
TIME OF CONCENTRATION -10 YR
LOCATION: Swallow Office
PROJECT NO: 9116.06
COMPUTATIONS BY: B. Stmnd
DATE: 12/19/00
10-yr storm Cf = 1.00
JR Engineering
2620 E. Prospect Rd., Ste. 190
Fort Collins, CO 80525
SUB -BASIN
DATA
INITIAL /OVERLAND
TIME (tl)
TRAVEL TIME I GUTTER OR CHANNEL FLOW
00
to CHECK
(URBANIZED BASIN)
FINAL
to
REMARKS
DESIGN
PONIT
SUBBASIN(s)
(1)
Existing
Area
(ac)
(2)
C
(3)
Length
(8)
(4)
Slope
(%)
(5)
ti
(min)
(8)
Length
(8)
(7)
Slope
(%)
(8)
n
Manning
rough.
Vel.
(Ns)
1 (9)
tt
(min)
1 (10)
to =
tl+tt
(11)
Total
(it)
(12)
tc=(1/180)+10
(min)
(13)
(min)
(14)
1
H1
0.02
0.85
100
2.6
3.4
0
1
0.016
2.0
0.00
3.4
100
10.8
5.0
2
H2
O.25
0.88
150
2.6
3.7
0
1
0.016
2.0
0.00
3.7
150
10.8
5.0
Proposed
1
101
0.02
0.19
15
2
5.2
70
1
0.016
2.0
0.58
5.8
85
10.5
5.8
2
102
0.25
0.79
70
1
4.9
110
1
0.016
2.0
0.91
S.
180
11.0
5.8
EQUATIONS:
tc=III +It
ti = [1.87 (1.1 - CCI ) Le'5 ] /. S 113
It = L/Vel.
Velocity from Manning's Equation with R=0.1 (corresponds to Figure 3-3 of City of Fort Collins Design Manual)
final tc = minimum of ti + It and urbanized basin check
min. It: = 5 min. due to limits of IDF curves
911606flow.xls
J
RUNOFF COEFFICIENTS & % IMPERVIOUS
LOCATION: Swallow Office
PROJECT NO: 9116.06
COMPUTATIONS BY: B. Strand
DATE: 12/19/00
Recommended Runoff Coefficients from Table 3-3 of City of Fort Collins Design Criteria
Recommended % Impervious from Urban Storm Drainage Criteria Manual
Streets, parking lots (asphalt):
Sidewalks (concrete):
Roofs:
Lawns (flat <2%, sandy soil):
Runoff
%
coefficient
Impervious
C
0.95
100
0.95
96
0.95
90
0.10
0
JR Engineering
2620 E. Prospect Rd., Ste. 190
Fort Collins, CO 8525
SUBBASIN
DESIGNATION
TOTAL
AREA
(ar—)
TOTAL
AREA
(sq.ft)
ROOF
AREA
(sq.ft)
PAVED
AREA
(sq.ft)
SIDEWALK
AREA
(sq.ft)
LANDSCAPE
AREA
(sq.ft)
RUNOFF
COEFF.
(C)
%
Impervious
Existing
Hi
0.02
996
0
883
0
113
0.85
89
H2
O.25
10,971
1,215
6,853
0
903
0.88
91
Proposed
101
0.02
954
0
0
99
855
0.19
10
102
0.25
11,014
2,775
5,359
75
2,101
0.79
78
Equations
- Calculated C coefficients & % Impervious are area weighted
C=E(Ci Ai) /At
Ci = runoff coefficient for specific area, Ai
Ai = areas of surface with runoff coefficient of Ci
n = number of different surfaces to consider
At = total area over which C is applicable; the sum of all Ai's
911606flow.xls
LARIMER COUNTY AREA, COLORADO
Capability units IIe-1, irrigated, and IIIe-6, dryland;
Clayey Foothill range site; windbreak suitability group
1.
75—Nunn clay loam, 3 to 5 percent slopes. This
gently sloping soil is on high terraces and fans. This
soil has a profile similar to the one described as rep-
resentative of the series, but the combined thickness
of the surface layer and subsoil is about 24 inches.
Included with this soil in mapping are small areas
of soils that are more sloping or less sloping and a few
small areas of soils that have a surface layer of light
clay. Also included are a few small areas of Satanta
and Ulm soils.
Runoff is medium. The hazard of water erosion is
moderate, and the hazard of wind erosion is slight.
If irrigated, this soil is suited to barley, alfalfa, and
wheat and, to a lesser extent, corn, sugar beets, and
beans. Under dryland management it is suited to wheat
or barley. It is also well suited to pasture and native
grasses. Capability units IIIe-2, irrigated, and IIIe-7,
dryland; Clayey Foothill range site; windbreak suit-
ability group 1.
76—Nunn clay loam, wet, 1 to 3 percent slopes. This
nearly level, somewhat poorly drained soil is on low
terraces and alluvial fans, commonly adjacent to
drainageways. This soil has a profile similar to the one
described as representative of the series, but a seasonal
high water table is at a depth of 20 to 30 inches during
part of the growing season.
Included with this soil in mapping are a few small
areas of soils that have a strongly alkaline surface
layer and a few small areas of soils that are moderately
well drained. Also included are a few areas of soils
that have a surface layer of loam or clay and a few
areas of soils that are less sloping.
Runoff is slow, and the hazard of erosion is slight.
This soil is suited to pasture and hay. If the water
table is lowered by management practices, corn, sugar
beets, wheat, and barley can be grown. Capability unit
IIIw-1, irrigated; Wet Meadow range site; windbreak
suitability group 5.
Otero Series
The Otero series consists of deep, well drained soils
that formed in alluvium and wind -deposited material.
These soils are on alluvial fans and terraces. Elevation
ranges from 4,800 to 5,600 feet. Slopes are 0 to 15
percent. The native vegetation is mainly blue grama,
needlegrass, bluestems, and some forbs and shrubs.
Mean annual precipitation ranges from 13 to 15 inches,
mean annual air temperature ranges from`48° to 50'
F, and the frost -free season ranges from 135 to 150
days.
In a representative profile the surface layer is brown
sandy loam about 4 inches thick. The underlying
material is pale brown sandy loam about 13 inches
thick over light brownish gray sandy loam.
Permeability is rapid, and the available water ca-
pacity is medium. Reaction is mildly alkaline above a
depth of about 4 inches and moderately alkaline below
that depth.
These soils are used mainly for native grasses and
for dryfarmed crops. A few areas are used for ir-
rigated crops.
43
Representative profile of Otero sandy loam in an
area of Otero -Nelson sandy loams, 3 to 25 percent
slopes, in native grass, about 300 feet south and 1,420
feet west of the northeast corner of sec. 11, T. 10 N.,
R. 68 W. :
A1=0 to 4 inches; brown QOYR 5/3) sandy
loam, dark brown (10YR 3/3) moist;
weak very fine granular structure; soft,
very friable; calcareous; mildly alka-
line; clear smooth boundary.
Clca--4 to 17 inches; pale brown (10YR 6/3)
sandy loam, brown (10YR 5/3) moist;
weak medium and coarse subangular
blocky structure; hard, very friable; cal-
careous; visible calcium carbonate as few
soft spots; moderately alkaline; gradual
smooth boundary.
C2ca-17 to 60 inches; light brownish gray
(10YR 6/2) sandy loam, dark grayish
brown (10YR 4/2) moist; massive; hard,
very friable; calcareous; visible calcium
carbonate as few soft spots; moderately
alkaline.
The A horizon is sandy loam or fine sandy loam 8 to
12 inches thick in cultivated areas. The C horizon is
sandy loam or fine sandy loam. The soil is generally
calcareous throughout, but the surface layer is leached
in places. Distribution of lime in the profile is erratic.
Soft sandstone is at a depth of 40 to 60 inches in some
profiles.
77—Otero sandy loam, 0 to 3 percent slopes. This
nearly level soil is on uplands and fans. This soil has a
profile similar to the one described as representative of
the series, but the surface layer is about 10 to 12
inches thick.
Included with this soil in mapping are some small
areas of soils that have a surface layer of loam or fine
sandy loam. Also included are some areas of soils that
are redder and a few small areas of Ascalon, Nelson,
and Kim soils.
Runoff is slow. The hazard of water erosion is slight,
and the hazard of wind erosion is moderate.
If irrigated, this soil is suited to corn, barley, sugar
beets, wheat, and beans. Under dryland management
it is suited to pasture and native grasses and, to a
lesser extent, wheat and barley. Capability units
IIIe-5, irrigated, and IVe-5, dryland; Sandy Plains
range site; windbreak suitability group 2.
78—Otero sandy loam, 3 to 5 percent slopes. This
gently sloping soil is on uplands and fans. This soil
has a profile similar to the one described as representa-
tive of the series, but the surface layer is about 8
inches thick.
Included with this soil in mapping are a few small
areas of soils that are more sloping or less sloping.
Also included are some small areas of soils in which
sandstone is at a depth of 40 to 60 inches and a few
small areas of Ascalon, Nelson, and Kim soils.
Runoff is medium, and the hazard of erosion is
moderate.
If irrigated, this soil is suited to barley, wheat,
alfalfa, and pasture and, to a lesser extent, corn and
beans. Under dryland management it is well suited to
pasture and native grasses. Capability units IIIe-4,
irrigated, and VIe-2, dryland; Sandy Plains range
site; windbreak suitability group 2.
42
SOIL SURVEY
4/3) moist; moderate medium and coarse
prismatic structure parting to moderate
medium subangular blocky; very hard,
firm, very sticky and very plastic; thin
nearly continuous clay films on peds ;
noncalcareous; mildly alkaline; clear
smooth boundary.
B3ca-24 to 29 inches; pale brown (10YR 6/3 )
clay loam, brown (10YR 5/3) moist;
weak medium subangular blocky struc-
ture; very hard, firm, very plastic; few
thin patchy films. on ped faces; visible
calcium carbonate occurring as small
nodules; calcareous; moderately alka-
line; gradual smooth boundary.
Clca-29 to 47 inches; light yellowish brown
(10YR 6/4) clay loam, dark yellowish
brown (10YR 4/4) moist; massive; very
hard, firm, sticky and plastic; visible
calcium carbonate occurring as nodules,
thin seams, and streaks; calcareous;
moderately alkaline; gradual smooth
boundary.
C2ca-47 to 60 inches; light yellowish brown
(2.5Y 6/3) clay loam, light olive brown
(2.5Y 5/3) moist; massive; very hard,
firm, sticky and plastic; some visible
calcium carbonate but less than in the
Clca horizon; calcareous; moderately
alkaline.
The A horizon is light clay loam or clay loam 10 to
12 inches thick in cultivated areas. The combined thick-
ness of the A and B horizons ranges from 16 to 40
inches. The B2t horizon is heavy clay loam or light
clay. Depth to calcareous material ranges from 10 to
30 inches. Sand and gravel are below a depth of
inches in some profiles. Some profiles have substx
with a redder hue.
73---Nunn clay loam, 0 to 1 percent slopes. 7
level soil is on high terraces and fans. This soil hs
profile similar to the one described as representative
the series, but the combined thickness of the surf
layer and subsoil is about 35 inches.
Included with this soil in mapping are small ax
of soils that are more sloping. Also included are a :
small areas of Satanta, Fort Collins, and Ulm soils;
a few small areas of soils that have a surface layer;
subsoil of silty clay loam.
Runoff is slow, and the hazard of erosion is slight.
If irrigated, this soil is suited to corn, sugar be
beans, barley, wheat, and alfalfa. Under dryl;
management it is suited to wheat or barley. It is
suited to pasture and native grasses. Capability ui
IIs-1, irrigated, and IIIc-1, dryland ; Clayey Foot
range site; windbreak suitability group 1.
74—Nunn clay loam, 1 to 3 percent slopes. 7
nearly level soil is on high terraces and fans. This ;
has the profile described as representative of
series.
Included with this soil in mapping are a few sn
areas of soils that are more sloping or less sloping.
a few small areas of soils that have a surface layer.
subsoil of silty clay loam. Also included are small ar
of Satanta, Fort Collins, and Ulm soils.
Runoff is slow to medium, the hazard of wind eros
is slight, and the hazard of water erosion is moderal
If irrigated, this soil is suited to corn, sugar beq
beans, barley, alfalfa, and wheat. Under dryly
management it is suited to wheat and barley. It is a
well suited to pasture or native grasses (fig. 1
l'/���T,.:
Figure 10.—Alfalfa bales on Nunn clay loam, 1 to 3 percent slopes.
12
SOIL SURVEY
sloping to strongly sloping soil is on terrace edges,
fans, and benches. This soil has a profile similar to the
one described as representative of the series, but the
combined thickness of the surface layer and subsoil
is about 18 to 19 inches.
Included with this soil in mapping are some areas
of soils that are more sloping and some areas of soils
that have a surface layer of sandy loam. Also included
are small areas of Larimer, Stoneham, and Larim soils.
Runoff is medium, and the hazard of erosion is mod-
erate to severe.
This soil is suited to wheat and barley under dryland
management. If irrigated, it is also suited to alfalfa.
It is well suited to pasture and native grasses. Capabil-
ity units IVe-1, irrigated, and IVe-3, dryland; Loamy
Plains range site; windbreak suitability group 1.
3—Altvan-Satanta loams, 0 to 3 percent slopes. This
complex consists of nearly level soils on terraces and
high benches. It is about 45 percent Altvan loam and
about 30 percent Satanta loam. The soils are inter-
mingled throughout the mapped areas, but Altvan
loam commonly is more sloping and Satanta loam is
more nearly level and is in some depressions. The
Altvan soil has a profile similar to the one described as
representative of the Altvan series, but, the surface
layer commonly is about 8 to 11 inches thick and is
loam or sandy loam. The Satanta soil has a profile
similar to the one described as representative of the
Satanta series, but the surface layer is about 8 to 11
inches thick and is sandy loam in places. In places
both soils are redder than is typical of their respective
series.
Included with these soils in mapping is about 15
percent Nunn soils.
Runoff is slow to medium, and the hazards of wind
and water erosion are slight to moderate.
If irrigated, these soils are suited to corn, sugar
beets, dry beans, alfalfa, and small grain. Under dry -
land management they are suited mainly to wheat,
but other small grain, such as barley and oats, is some-
times grown. The soils are also well suited to pasture
and native grasses. Capability units IIIe-3, irrigated,
and IIIe-6, dryland; Loamy Foothill range site; wind-
break suitability group 1.
4—Altvan-Satanta loamy, 3 to 9 percent slopes. This
complex consists of gently sloping or strongly sloping
soils on high terraces, benches, and fans. It is about
55 percent Altvan loam and 35 percent Satanta loam.
Altvan loam is mainly more sloping, and Satanta loam
is smoother. These soils have profiles similar to the
ones described as representative of their respective
series, but the surface layer is sandy .loam and loam
and the surface layer and subsoil are thinner. Many
areas of both soils are redder than is typical of their
respective series.
Included with these soils in mapping is about 10
percent Nunn and Larimer soils.
Runoff is medium to rapid, and the hazards of wind
and water erosion are moderate.
If irrigated, these soils are well suited to alfalfa,
small grain, and pasture. Under dryland management
they are suited to wheat and barley. They are also
suited to pasture and native grasses. Capability units
IVe-1, irrigated, and IVe-3, dryland; Loamy Foothill
range site; windbreak suitability group 1.
Aquepts, Loamy
5—Aquepts, loamy. These nearly level or gent
sloping, poorly drained soils are in depressional are
on uplands, along drainageways, and on side slop
below large canals. The surface layer is fine san.
loam, loam, or clay loam. The underlying layer
mainly loam or clay loam extending to a depth of
to 60 inches or more. A water table is at or near t
surface in spring and summer.
Included with these soils in mapping are a few sm;
areas of Stoneham, Fort Collins, and Kim soils ai
Nunn clay loam, wet.
Runoff is slow to medium, and the hazard of wat
erosion is slight to moderate.
These soils are suited to pasture and native grassi
A few areas are used for hay. If drained, the soils a
suited to crops. The main irrigated crops are bark
corn, sugar beets, and wheat. Capability units IIIw-
irrigated, and Vw-1, dryland; Wet Meadow range sit
windbreak suitability group 5.
Aquepts, Ponded
6—Aquepts, ponded. These nearly level soils a
near stream channels and drainageways. A wat
table is at or near the surface most of the year. T
soils are extremely variable. The native vegetation
mainly cattails, sedges, and rushes.
These soils offer very little grazing but are suital
for wildlife habitat. Capability unit,VIIIw-1, drylan
not assigned to a range site or windbreak suitabili
group.
Ascalon Series
The Ascalon series consists of deep, well drain
.soils that formed in mixed wind -deposited materi
These soils are on uplands and foot slopes. Elevati
ranges from 4,800 to 5,700 feet. Slopes are 0 to 5 p(
cent. The native vegetation is mainly blue grama a:
other short grasses and forbs. Mean annual precipil
tion ranges from 13 to 15 inches, mean annual i
temperature ranges from 480 to 500 F, and the fro.
free season ranges from 135 to 150 days.
In a representative profile the surface layer is broi
sandy loam about 6 inches thick. The subsoil is broi
and pale brown sandy clay loam about 14 inches thi4
The underlying material is pale brown or very p.
brown sandy loam.
Permeability is moderate, and the available wal
capacity is medium to high. Reaction is neutral abc
a depth of about 16 inches and moderately alkali
below that depth.
These soils are used mainly for irrigated and di
farmed crops. Some small areas are used for nat'.
grasses.
Representative profile of Ascalon sandy loam, 0
3 percent slopes, in a cultivated area, about 400 f8
east and 650 feet south of the northwest corner of s
36, T. 5 N., R. 68 W.:
Ap-0 to 6 inches; brown (10YR 5/3) san
loam, dark brown (IOYR 3/3) moi
weak medium subangular blocky str
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APPENDIX
5. REFERENCES
1. City of Fort Collins, "Storm Drainage Design Criteria and Construction Standards"
(SDDCCS), May 1984.
2. "Final Report for Hydrologic Model Update for the Foothills Baisn Master Drainage
Plan", July 15, 1999, Anderson Consulting Engineers. .
3. Soil Survey of Larimer County Area, Colorado. United States Department of
Agriculture Soil Conservation Service and Forest Service, 1980.
4. .Urban Drainage and Flood Control District, "Urban Storm Drainage Criteria
Manual", Volumes 1 and 2, dated March 1969, and Volume 3, dated September
1992.
Final Drainage and Erosion Control Report Page 7
Swallow Office March 20, 2001
4.5 Permanent Stabilization
All soils exposed during land disturbing activity (stripping, grading, utility installations,
stockpiling, filling, etc.) shall be kept in a roughened condition by ripping or disking along
land contours until mulch, vegetation or other permanent erosion control is installed. No
soils in areas outside project street rights of way shall remain exposed by land disturbing
activity for more than thirty (30) days before required temporary or permanent erosion
control (e.g. seed/ mulch, landscaping, etc.) is installed, unless otherwise approved by the
Stormwater Utility. Vegetation shall not be considered established until a ground cover is
achieved which is demonstrated to be mature and stable enough to control soil erosion as
specified in paragraph 11.3.10 of the City of Fort Collins Storm Drainage Constnzction
Standards.
Final Drainage and Erosion Control Report Page 6
Swallow Office March 20, 2001
included in the Appendix. Water quality will be controlled by routing as much runoff as
possible through grass swales and in sheet flow across proposed landscape areas.
4.2 Dust Abatement
During the performance of the work required by these specifications or any operations
appurtenant thereto, whether on right-of-way provided by the City or elsewhere, the
contractor shall furnish all labor, equipment, materials, and means required. The Contractor
shall carry out proper efficient measures wherever and as necessary to reduce dust nuisance,
and to prevent dust nuisance that has originated from his operations from damaging crops,
orchards, cultivated fields, and dwellings, or causing nuisance to persons. The Contractor
will be held liable for any damage resulting from dust originating from his operations under
these specifications on right-of-way or elsewhere.
4.3 Tracking Mud on City Streets
It is unlawful to track or cause to be tracked mud or other debris onto city streets or rights -of -
way unless so ordered by the Director of Engineering in writing. Wherever construction
vehicles access routes or intersect paved public roads, provisions must be made to minimize
the transport of sediment (mud) by runoff or vehicles tracking onto the paved surface.
Stabilized construction entrances are required per the detail shown on the Erosion Control
Plan, with base material consisting of 6" coarse aggregate. The contractor will be
responsible for clearing mud tracked onto city streets on a daily basis.
4.4 Maintenance
All temporary and permanent erosion and sediment control practices must be maintained and
repaired as needed to assure continued performance of their intended function. Straw bale
dikes or silt fences will require periodic replacement. Sediment traps (behind straw bale
barriers) shall be cleaned when accumulated sediments equal approximately one-half of trap
storage capacity. Maintenance is the responsibility of the developer.
Final Drainage and Erosion Control Report Page 5
Swallow Office March 20, 2001
3.2 General Flow Routing
Flows within this site will take the form of overlot and gutter flow. The existing drainage
patterns have been maintained as much as possible.
Stormwater Detention is not required for Swallow Office because impervious values are not
increased. Flows to the north (Subbasin 101) will travel overland to Swallow Road. Flows
to the south (Subbasin 102) will be conveyed via overland flow and gutter flow to the
concrete pan on Remington Street. The existing concrete trickle pan will be removed.
A swale has been graded along the west property line to convey flows south. The 10-year and
100-year existing and future flows are provided in the appendix and summarized in Table
3.1.
Table 3.1 Drainage Summary
HISTORIC DRAINAGE SUMMARY TABLE
Design
Point
Tributary
Sub -basin
Area
(ac)
C (10)
c (100)
tc (10)
(min)
tc (100)
(min)
Q(10)tot
(cfs)
Q(100)tot
(ds)
1
H1
0.02
0.85
1.00
5.0
5.0
0.10
0.23
2
H2
O.25
0.88
1.00
5.0
5.0
1.08
251
4. EROSION CONTROL
4.1 Erosion and Sediment Control Measures
Erosion and sedimentation will be controlled during construction by inlet filters, silt fences,
gravel construction entrances, seeding and mulching. These measures are designed to limit
the overall increase in sediment yield due to construction activities as required by the City
of Fort Collins. During overlot and final grading, the soil will be roughened and furrowed
perpendicular to the prevailing winds. The required. erosion control escrow is $2,130.67.
Construction is scheduled to begin in Spring 2001 and be completed by Winter 2001. The
erosion control cost estimate, effectiveness calculations and a construction schedule are
Final Drainage and Erosion Control Report Page 4
Swallow Office March 20, 2001
3. LOCAL DEVELOPED DRAINAGE DESIGN
3.1 Method
Since the subbasins are less than 160 acres, the Rational Method was used to determine both
the 10-year and 100-year runoff rates for the sub -basins indicated in this drainage report.
Drainage facilities were designed to convey the 100-year peak flows. The Runoff coefficients
were assigned using Table 3-2 of the SDDCCS Manual. The Rational Method is given by:
Q = CrCIA (1)
where Q is the maximum rate of runoff in cfs, A is the total area of the basin in acres, Cr is
the storm frequency adjustment factor, C is the runoff coefficient, and I is the rainfall
intensity in inches per hour for a storm duration equal to the time of concentration. The
frequency adjustment factor, Cr, is 1.0 for the initial 10-year storm and 1.25 for the major
100-year storm. The runoff coefficient is dependent on land use or surface characteristics.
The rainfall intensity is selected from Rainfall Intensity Duration Curves for the City of Fort
Collins (Figure 3.1 of SDDCCS). In order to utilize the Rainfall Intensity Duration Curves,
the time of concentration is required. The following equation is used to determine the time
of concentration
t'=ti+tt
(2)
where t. is the time of concentration in minutes, t; is the initial or overland flow time in
minutes, and t, is the conveyance travel time in minutes. The initial or overland flow time
is calculated with the SDDCCS Manual equation:
t = [1.87(1.1 - CQL0.5)/(S)0.33
(3)
where L is the length of overland flow in feet (limited to a maximum of 500 feet), S is the
average slope of the basin in percent, and C and Cf are as defined previously.
Final Drainage and Erosion Control Report Page 3
Swallow Office March 20, 2001
1.5 Master Drainage Basin
Swallow Office lies in the Foothills Drainage Basin. The site lies in Basin 25 as defined by
the Final Report for Hydrologic Model Update for the Foothills Basin Master Drainage Plan
(Anderson, 1999). Basin 25 is a commercial basin with 90 % imperviousness and a 1.5%
slope that drains to the Foothills Regional Channel east of Stanford Road.
2. HISTORIC (EXISTING) DRAINAGE
The historic (existing) flows for Lot 2, Block 3, Thunderbird Estates Ninth Subdivisiodare
split north and south. A small portion of the lot drains north to Swallow Road, with the
remainder draining south to a concrete pan .which runs through Southmoor Village 5' Filing
(Ross Department Store). Both flow paths join downstream at the Foothills Regional
Channel, east of Stanford Road. The site has an average slope of 2.6 percent. The majority
of the site is paved with a small amount of landscaping. An existing 2' trickle pan conveys
flows toward the south lot line. This trickle pan ends short of the Ross Department Store
Parking Lot and currently cascade over bare soil. .
A small portion of the back of Lot 1, Block 3, Thunderbird Estates Ninth Subdivision
(Diamond Shamrock Filling Station) drains to the west property line of the site. This offsite
flow (Offsite Basin 01) appears to pond near the middle of the lot line until it spills to the
south. However, this area is intended to drain to the south and would function properly with
some corrections to the Diamond Shamrock site.
According to the Flood Insurance Rate Map (FIRM) for the area, the site lies out of the 100-
YR Floodplain. The site is shown on a portion of the FIRM Map Panel No. 0801020012C
in the Appendix.
Final Drainage and Erosion Control Report Page 2
Swallow Office March 20, 2001
1. INTRODUCTION
1.1 Project Description
Swallow Office is a proposed redevelopment located on Lot 2, Block 3, Thunderbird Estates
Ninth Subdivison. The site is located in the Foothills Drainage Basin and contains
approximately 0.27 Acres. The site is zoned C, Commercial. The proposed site is located
at the southwest comer of Swallow Road and Remington Street. The project is a portion of
Section 25, Township 7 North, Range 69 West of the Sixth Principal Meridian, in the City
of Fort Collins, Larimer County, Colorado. A vicinity map is provided in the Appendix.
1.2 Existing Site Characteristics
According to the "Soil Survey for Larimer County Area, Colorado" (USDA) soils include:
Altvan-Santana loam (3) & Nunn clay loam (74). These soils have slow to moderate runoff
and slight to moderate erosion. The site is within the moderate wind erodibility zone
according to the Wind Erodibility Map for the City of Fort Collins.
1.3 Purpose and Scope of Report
This report defines the proposed drainage and erosion control plan for Swallow Office. The
plan includes consideration of all on -site and tributary off -site runoff and the design of all
drainage facilities required for this development. This drainage plan maintains existing
drainage patterns.
1.4 Design Criteria
This report was prepared to meet or exceed the submittal requirements establislied in the City
of Fort Collins' "Storm Drainage Design Criteria and Construction Standards" (SDDCCS),
dated May 1984. Where applicable, the criteria established in the "Urban Storm Drainage
Criteria Manual" (UDFCD) dated 1984, developed by the Denver Regional Council of
Governments have been utilized.
Final Drainage and Erosion Control Report Page 1
Swallow Office March 20, 2001
TABLE OF CONTENTS
PAGE
TRANSMITTALLETTER..................:.......................................................................................... i
JREngineering......................................................................................................... i
TABLEOF CONTENTS................................................................................................................ ii
1.
INTRODUCTION
..................................................................................................................1
1.1
Project Description..........................................................................................................1
1.2
Existing Site Characteristics................................................................................:..........1
1.3
Purpose and Scope of Report ......................................................................:...................1
1.4
Design Criteria................................................................................................................1
1.5
Master Drainage Basin....................................................................................................2
2.
HISTORIC
(EXISTING) DRAINAGE................................................................................2
3.
LOCAL DEVELOPED DRAINAGE DESIGN
...................................................................3
3.1
Method............................................................................................................................3
3.2
General Flow Routing.....................................................................................................4
4.
EROSION
CONTROL.
........ o ......... — ...................... 4
4.1
Erosion and Sediment Control Measures........................................................................4
4.2
Dust Abatement...............................................................................................................5
4.3
Tracking Mud on City Streets.........................................................................................5
4.4
Maintenance....................................................................................................................5
4.5
Permanent Stabilization..................................................................................................6
5. REFERENCES.......................................................................................................................7
Appendix
March 20, 2001
Mr. Basil Harridan
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, CO 80521
j-R ENGINEERING
A Subsidiary of Westriao
RE: Final Drainage and Erosion Control Report for Swallow Office - Revised
Dear Basil,
We are pleased to submit to you for your approval, this revised Final Drainage and Erosion Control
Report for Swallow Office, a redevelopment of an existing car wash site. The site is located in Fort
Collins, Colorado at the southwest comer of the intersection of Swallow Road and Remington Street.
This report includes revisions based on Stormwater's review comments dated January 25, 2001.
All computations within this report have been completed in compliance with the City of Fort Collins
Storm Drainage Design Criteria.
We greatly appreciate your time and consideration in reviewing this submittal. Please call if you
have any questions.
Sincerely,
JR ENGINEERING
1;2W
David W. Klockema , PE
Division Manager
Attachments
2620 East Prospect Road, Suite 190, Fort Collins, CO 80525
970-491-9888 • Faz: 970-491-9984 • w ..jrengineering.com
FINAL DRAINAGE AND
EROSION CONTROL REPORT
Swallow Office -
Lot 2, Block 3, Thunderbird Estates Ninth Filing
Prepared for:
Lagunitas Companies
3950 JFK Parkway
Building 12B
Fort Collins, Colorado 80525
(970)226-5000
Prepared by:
JR Engineering
2620 E. Prospect Road, Suite 190
Fort Collins, Colorado 80525
(970)491-9888
December 21, 2000
Revised: March 20, 2001
Job Number 9116.06