HomeMy WebLinkAboutDrainage Reports - 05/21/2008 (2)STORMWATER
City of Ft..Collinsrov Plans RECEIVED
Approved By. {^ t
Date 0 APR 2 5 2008
FINAL DRAINAGE STUDY
FOR
HAR SHALOM MINOR SUBDIVISION
LOT 1, PARKING LOT & DRIVEWAY EXPANSION
February 20, 2008
Revised April 18, 2008
Prepared for:
Congregation Har Shalom
725 West Drake Road
Fort Collins, CO 80527
Prepared by:
Mary Mateo, EI
Stewart & Associates, Inc.
PO Box 429
103 S. Meldrum St.
Fort Collins, CO 80521
Phone: (970) 482-9331
Fax: (970)482-9382
TABLE OF CONTENTS
PAGE
I. GENERAL LOCATION AND DESCRIPTION
A. SITE LOCATION 3
B. DESCRIPTION OF PROPERTY 3-4
II. DRAINAGE BASINS AND SUB -BASINS
A. MAJOR BASIN DESCRIPTION 4
B. SUB -BASIN DESCRIPTION 4-5
III. DRAINAGE DESIGN CRITERIA
A. REGULATIONS 5
B. HYDROLOGICAL CRITERIA 5
C. HYDRAULIC CRITERIA 6
D. VARIANCES GRANTED 6
IV. DRAINAGE FACILITY DESIGN
A. GENERAL CONCEPT 6-7
B. SPECIFIC DETAILS 7
VI. CONCLUSIONS 7
VII. REFERENCES 8
VIII. APPENDICES 9
2
CERTIFICATION
I hereby certify that this report for the final drainage design of the Har
Shalom was prepared by me (or under my direct supervision) in accordance
with the provisions of the City of Fort Collins Storm Drainage Design
Criteria and Construction Standards, for the owners thereof.
Kevin Forbes
Registered Professional Engineer
State of Colorado No. 35265
I. GENERAL LOCATION AND DESCRIPTION
A. Location
Har Shalom (Project Site) is located in the northwest quarter of
Section 26, Township 7 North, Range 69 West of the 6`s Principal
Meridian, City of Fort Collins, County of Larimer, State of Colorado.
It is Lot One of the Har Shalom Minor Subdivision. The Site is
bounded on the North by Drake Road, on the East by single-family
residences of the Meadowlark Heights Subdivision, and on the South
and West by the New Mercer Canal. A Vicinity Map is provided in
the Appendix.
B. Description of Property
The total Site area is approximately 1.64 acres. Existing infrastructure
on the lot includes asphalt parking areas, a gravel turn -around area,
concrete walkways, and three buildings. The Site currently drains to
two onsite inlets — one in the existing gravel turn -around area at the
southeast corner of the Site, and the other at the edge of the asphalt
parking area in the southwest corner of the Site. These flows are
carried from the Site via the outlet pipe from the Woodwest detention
pond south of the Site. This 60" RCP pipe drains north across Drake
Road and then east to the CSU Veterinary Hospital detention pond.
The outlet from the Veterinary Hospital pond drains north to Spring
Creek.
This project proposes to relocate one of the existing buildings
(modular), construct a new 2 1 00-square-foot building (modular), turn
the existing gravel tum-around area to asphalt parking, and extend a
drive from that parking area northward along the eastern boundary to
Drake Road. An increase of approximately 16,660 square feet in hard
surface will result from these improvements, creating an increase in
required detention volume. Detention is currently being provided
onsite in the parking area at the southeast corner of the Site.
There is also the possibility of another building being constructed at
the north end of the site along West Drake Road at some point in the
future. That building is not currently being considered for
3
construction, but is accounted for in the drainage calculations for this
report, including required detention volume.
As previously stated, the New Mercer Canal runs along the northern
and eastern boundaries of the Site. No runoff is currently being
directed to this canal, and no runoff to the canal will be created by the
proposed improvements to the Site.
Soil classifications for the Site are made up of Nunn clay loam (0-1 %
slopes). See the Soil Conservation map and descriptions provided in
the Appendix. This soil belongs to the hydrologic soil group C, as
assigned by the Natural Resources Conservation Service. They are
deep and well drained, with slow permeability. Runoff is slow, and
the hazard of erosion is slight.
II. DRAINAGE BASINS AND SUB -BASINS
A. Major Basin Description
This site lies within the Spring Creek drainage basin of the City of Ft.
Collins. It is not within any floodplain boundary, as evidenced by the
City of Fort Collins Flood Map and the FEMA Flood Insurance Rate
Map #08069CIND2A. The Site is located on Panel 1000F of the
FEMA map, which is an imprinted panel and contains "no special
flood areas." Previous drainage studies have been done for this Site,
with the most current being done in 1995. That report addressed
changes created by the addition of a building and some walks at that
time.
B. Sub -Basin Description
Drainage patterns for this Site will not change significantly with the
proposed construction. Existing drainage conditions are shown on the
attached Grading, Drainage and Erosion Control Plan for the Site,
which is dated 07/28/95. The Site was divided into two basins. Basin
1 lies on the western side of the Site and is approximately 0.60 acres
in area. This basin drains to the inlet at the southwest comer of the
Site. Proposed construction will affect Basin 1 so minimally, that
calculations have been completed only for changes to Basin 2.
4
Basin 2 includes the eastern portion of the Site, and is approximately
1.05 acres in area. Most construction will occur within this basin,
which drains to the area inlet in the gravel turn -around area. This inlet
box was constructed with a 2.7" diameter restriction over the outlet
pipe in order to allow only the historic release rate of 0.27 cfs from
this area of the Site. No changes will be made to this restriction, and
the current release rate will remain virtually unchanged. With the
increase in depth at the outlet in the major storm, the release is 0.30
cfs. Flows will continue to be directed from this area inlet to the curb
inlet box for Basin 1, and to the outlet pipe from the Woodwest pond.
Detention will continue to be provided in the parking area at the
southeast comer of the Site, as well as in the road along its eastern
boundary. A watertight barrier curb will be constructed along the
southern boundary in order to provide the required detention volume.
Runoff will be conveyed overland to the inlets and detention area, and
then released via the 60" outlet pipe from the Westwood pond.
III. DRAINAGE DESIGN CRITERIA
A. Regulations
The analysis and design of the storm drainage system for this project
was prepared in accordance with the criteria set forth in the City of
Fort Collins Storm Drainage Design Criteria and Construction
Standards and the Urban Drainage and Flood Control District's
Urban Storm Drainage Criteria Manual (USDCMJ.
B. Hydrological Criteria
1. Design Rainfall City of Fort Collins Rainfall
Intensity -Duration -Frequency
Table for the Rational Method
(Figures 3-la and 3-1b)
2. Runoff Method Rational
3. Design Storms
a. Minor 2-year
b. Major 100-year
C. Hydraulic Criteria
The increase in necessary pond volume was calculated utilizing a
stage/storage spreadsheet provided by the City of Fort Collins. The
currently proposed improvements to the Site, in addition to the future
addition of the building along West Drake Road, create an increase in
required detention of 8,458 cubic feet, for a total required volume of
11,088 cubic -feet. The current outlet structure design will remain
unchanged.
E. Variances Granted
Two variances were granted for this project by the City of Fort
Collins' Stormwater Department. The first variance is the allowance
of parking spaces in areas where the 100-year water surface elevation
will be greater than one foot in depth. In some areas of the southeast
parking area, the water may be as deep as 1.55 feet. Signs will be
posted in these areas that read "During Large Rain Storms, Water
May Pond An Excess Of 12" in This Area."
The second variance involves the need for water quality measures for
the new runoff created by the development. Because the water exits
the Site at the area inlet in the middle of the southeast parking lot,
there will be no water quality plate at the outlet as would normally be
the case if detention were being provided in a pond. Water quality
measures will, however, be provided for the existing runoff by adding
a bio-swale to Basin 2 that will capture runoff from rooftops and open
areas, filtering it and directing it to the outlet via sidewalk chase along
the north side of the parking area.
IV. DRAINAGE FACILITY
A. General Concept
The intent of the proposed drainage system is to safely convey the 2-
year (minor) and 100-year (major) design storm runoff. Runoff will
be conveyed by surface drainage structures (i.e. drives, swales, curb
and gutter). Existing drainage patterns will be maintained and utilized
1.1
as practicality permits. The general pattern of flow is to the south,
with inlets located at the southeast and southwest corners of the Site.
B. Specific Details
The drive along the eastern side of the Site will be 24' wide near the
access at Drake Road and 20' wide to the south, with 6" vertical curb
and gutter along both sides. The proposed detention facility will be
privately owned and maintained.
Onsite detention will be developed within the drive and parking areas
at the south and east sides of the Site. A barrier curb will be installed
along the southern boundary in order to provide the required detention
volume of 11,988 cubic feet. At elevation 5040', approximately
22,897 cubic feet of detention volume is provided. This results in a
100-year water surface elevation of 5039.35' and 0.65' of freeboard.
The outlet from the detention area (Basin 2) is designed to release at
the historic rate, and will continue to do so with the proposed
improvements to the Site. As previously stated the inlets drain to the
outlet pipe from the Westwood pond. Detention will be released at
0.30 cfs. Outfall is ultimately to Spring Creek.
Erosion control measures will be utilized to mitigate erosion and
control sediment in compliance with City specifications. Standard
Best Management Practices will include, but are not limited to,
perimeter silt fencing, vehicle tracking control, and inlet protection.
V. CONCLUSIONS
The analysis and design of the storm drainage system for this project was
prepared in accordance with the criteria set forth in the City of Fort Collins
Storm Drainage Design Criteria and Construction Standards and the
USDCM. No adverse affects to surrounding properties are anticipated from
the development of this site. The design, if properly maintained and
constructed, conveys, releases and protects the quality of storm water runoff
up to and including the 100-year storm event in a safe manner to protect life
and limit damage to property.
li
VI. REFERENCES
1. Urban Storm Drainage Criteria Manual Volumes I and 2,
Urban Drainage and Flood Control District, June 2001, and
Volume 3, September 1999.
2. City of Fort Collins Storm Drainage Design Criteria and
Construction Standards, Department of Public Works and
Water Utilities, Storm Drainage Division, May, 1984.
3. Soil Survey of Larimer County Area, Colorado, U.S.
Department of Agriculture, Soil Conservation Service and
Forest Service, December, 1980.
t8
VII. APPENDICES
Vicinity Map
Soils Data
2. Proposed Storm Drainage Calculations
Detention Pond Calculations
3. Historic Drainage Map (insert)
Proposed Drainage Map (insert)
HAR SHALOM
VICINITY MAP
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]05^07'30"
LARIMER COUNTY AREA, COLORADO
sandy loam. Depth to calcareous material is 0 to 4
inches.
71—Nelson fine sandy loam, 3 to 9 percent slopes.
This gently sloping to moderately sloping soil is on
uplands.
Included with this soil in mapping are small areas
of soils that are more sloping or less sloping. Also in-
cluded are some small areas of Otero and Tassel soils.
Runoff is medium, and the hazard of erosion is
severe.
If irrigated, this soil is suited to pasture and, to a
lesser extent, barley and wheat. Under dryland man-
agement it is suited to pasture or native grasses. Capa-
bility units IVe-2, irrigated, and VIe-2, dryland;
Sandy Plains range site; windbreak suitability group
2.
Newfork Series
The Newfork series consists of deep, somewhat
poorly drained soils that formed in alluvium. These
soils are on low terraces and flood plains and are
underlain by sand and gravel at a depth of 10 to 20
inches. Elevation ranges from 7,800 to 8,800 feet.
Slopes are 0 to 3 percent. The native vegetation is
mainly timothy, redtop, sedges, rushes, and water -
tolerant grasses. Mean annual precipitation ranges
from 12 to 16 inches, mean annual air temperature
ranges from 42' to 44' F, and the frost -free season
ranges from 60 to 85 days.
In a representative profile a 1-inch-thick layer of
organic material is on the surface. The surface layer
is mottled grayish brown sandy loam about 4 inches
thick. The subsoil is mottled dark brown heavy sandy
loam 6 inches thick. Below this is mottled sand and
gravel.
Permeability is moderately rapid above a depth of
about 10 inches and very rapid below that depth. The
available water capacity is low. Reaction is slightly
acid.
These soils are used for irrigated hay.
Representative profile of Newfork sandy loam, 0 to 3
percent slopes, in native grass, about 1,500 feet west
and 1,300 feet south of the northeast corner of sec. 18,
T. 11 N., R. 76 W.:
01-1 inch to 0; undecomposed and partly de-
composed organic material.
Alg-0 to 4 inches; grayish brown (10YR 5/2)
sandy loam, very dark grayish brown
(10YR 3/2) moist; common medium
distinct yellowish red (5YR 4/6) mot-
tles; weak medium subangular blocky
structure parting to weak fine and
medium granular structure; slightly
hard, very friable; 5 percent gravel;
slightly acid; clear smooth boundary.
B2g-4 to 10 inches; dark brown (7.5YR 4/2)
heavy sandy loam, dark brown (7.5YR
3/2) moist; moderate fine distinct red
(2.5YR 5/8) mottles; moderate medium
subangular blocky structure; hard, very
friable; 10 percent gravel; slightly acid;
gradual wavy boundary.
IICg-10 to 60 inches; sand and gravel; many
41
medium distinct bright colored mottles;
slightly acid.
The A horizon is loam, sandy loam, or sandy clay
loam 3 to 10 inches thick. The B2g horizon is sandy
loam or light sandy clay loam. The A and B horizons
range from slightly acid to neutral. Content of rock
fragments ranges from 0 to 15 percent in the upper
part of the profile and from 35 to 70 percent in the
lower part.
72—Newfork.sandy loam, 0 to 3 percent slopes. This
nearly level soil is on low terraces, flood plains, and
fans.
Included with this soil in mapping are small areas
of gravel bars. Also included are a few small areas of
soils in which gravel and sand is at a depth of 20 to
40 inches and a few small areas of Foxcreek soils.
Runoff is slow, and the hazard of erosion is slight.
If irrigated; this soil is suited to hay or pasture.
Capability unit VIw-1, irrigated; Mountain Meadow
range site; not assigned to a windbreak suitability
group.
Nunn Series
The Nunn series consists of deep, well drained soils
that formed in alluvium. These soils are on terraces and
alluvial fans. Elevation ranges from 4,800 to 5,600 feet.
Slopes are 0 to 5 percent. The native vegetation is
mainly blue grama, buffalograss, needlegrass, and
wheatgrasses. 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 gray-
ish brown light clay loam about 6 inches thick. The
subsoil is grayish brown or pale brown clay loam about
23 inches thick. The underlying material is light
yellowish brown clay loam.
Permeability is slow and the available water capac-
ity is high. Reaction is neutral above a depth of 10
inches, mildly alkaline between depths of 10 and
24 inches, and moderately alkaline below a depth of 24
inches.
These soils are used mainly for irrigated and dry -
farmed crops and for pasture. A few areas are used for
native grasses.
Representative profile of Nunn clay loam, 1 to 3
percent slopes, in grass, near the east quarter -corner
of sec. 5, T. 6 N., R. 68 W.:
A1-0 to 6 inches; grayish brown (10YR 5/2)
light clay loam, very dark grayish brown
(10YR 3/2) moist; moderate medium
granular structure; soft, very friable;
noncalcareous; neutral; clear smooth
boundary.
B1-6 to 10 inches; grayish brown (10YR 5/2)
clay loam, very grayish brown (10YR
3/2) moist; weak medium prismatic
structure parting to moderate medium
subangular blocky; hard, very friable,
plastic and sticky; few thin patchy clay
films on peds; noncalcareous; neutral;
clear smooth boundary.
B2t-10 to 24 inches; pale brown (10YR 6/3)
heavy clay loam, dark brown (10YR
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.
133ca-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 40
inches in some profiles. Some profiles have substrata
with a redder hue.
73—Nunn clay loam, 0 to 1 percent slopes. This
level soil is on high terraces and fans. 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 35 inches.
Included with this soil in mapping are small areas
of soils that are more sloping. Also included are a few
small areas of Satanta, Fort Collins, and Ulm soils and
a few small areas of soils that have a surface layer and
subsoil of silty clay loam.
Runoff is slow, and the hazard of erosion is slight.
If irrigated, this soil is suited to corn, sugar beets,
beans, barley, wheat, and alfalfa. Under dryland
management it is suited to wheat or barley. It is also
suited to pasture and native grasses. Capability units
Its-1, irrigated, and IIIc-1, dryland; Clayey Foothill
range site; windbreak suitability group 1.
74—Nunn clay loam, 1 to 3 percent slopes. This
nearly level soil is on high terraces and fans. This soil
has the profile described as representative of the
series.
Included with this soil in mapping are a few small
areas of soils that are more sloping or less sloping and
a few small areas of soils that have a surface layer and
subsoil of silty clay loam. Also included are small areas
of Satanta, Fort Collins, and Ulm soils.
Runoff is slow to medium, the hazard of wind erosion
is slight, and the hazard of water erosion is moderate.
If irrigated, this soil is suited to corn, sugar beets,
beans, barley, alfalfa, and wheat. Under dryland
management it is suited to wheat and barley. It is also
well suited to pasture or native grasses (fig. 10).
Figure 10—Alfalfa bales on Nunn clay loam, 1 to 3 percent slopes.
132 SOIL SURVEY
4
TABLE 8. Soil and water features —Continued
Flooding
Depth to
Bedrock
Soil name and
Hydro-
seasonal
Potential
map symbol
logic
high
frost
group
Frequency
Duration
Months
water
table
Depth
Hardness
action
Feet
Inches
Kirtley—Continued:
*58:
Kirtley part ________
C
None ________
______________
______________
>6.0
20-40
Rippable __
Moderate.
Purner part --------
D
None ________
______________
______________
>6.0
10-20
Hard _____
Low.
LaPorte:
*59:
LaPorte part -------
C
None ________
______________
______________
>6.0
10-20
Rippable -_
Low.
Rock outcrop part.
Larim:
60---------
A
None --------
--------------
--------------
>6.0
>60
Low.
----------
Larimer:
6I-------------------
B
None ----------------------
--------------
>6.0
>60
-----------
Low.
*62:
Larimer part _______
B
None ________
______________
_____
>6.0
>60
-----------
Low.
Stoneham part -----
B
None ________
______________
______________
>6.0
>60
___________
Moderate.
Longmont:
63 ___________________
C
Common ____
Brief _______
March -July __
2.0-2.5
>60
-----------
High.
Loveland:
64 -------------------
C
Common _-__
Very brief ___
March-
1.5-2.5
>60
______ ____
High.
September.
Midway:
65 ___________________
D
None ________
--------------
_
>6.0
10-20
Rippable __
Moderate.
Minnequa:
66 ___________________
B
None --------
--------------
--------------
>6.0
20-40
Rippable __
Low.
*67:
Minnequa part -----
B
None ________
______________
______________
>6.0
20-40
Rippable __
Low.
LaPorte part _______
C
None ________
______________
______________
>6.0
10-20
Rippable __
Low.
Miracle:
68 ___________________
B
None ________
--------------
_____---__ ___
>6.0
20-40
Hard -----
Moderate.
Naz:
69, 70 ________________
A
None ----------------------
_
>6.0
>60
Hard __— _
Moderate.
Nelson:
71 ___________________
B
None --------
_ -------------
--------------
>6.0
20-40
Rippable __
Low.
Newfork:
72 ___________________
D
Occasional ___
Brief _______
April -July ___
0.54.0
>60
-----------
Low.
N :
73 74, 75_____________
C
None ----------------------
--------------
>6.0
>60
_______-- _
Moderate.
------------------
C
None -----------------------------------
1.5-2.5
>60
----------
Moderate.
Otero:
77, 78, 79 ------------
B
None ---------------------------------
>6.0
>60
----------
Low.
*80:
'
Otero part ---------
B
None --------
-------------
--------------
>6.0
>60
-----------
Low.
Nelson part ________
B
None ________
_ ____
______________
>6.0
20-40
Rippable __
Low.
Paoli:
81 ___________________
B
Rare --------
Very brief ___
May -June ___
>6.0
>60
-----------
Moderate.
Pendergrass:
*82:
Pendergrass part __-
D
None ______________________
__
>6.0
10-20
Hard -----
Low.
Rock outcrop part.
Soil name and
map symbol
*62—Cont.:
Stoneham part ----
Longmont:
63 -----------------
Loveland:
64 -----------------
Midway:
65 _________________
Minnequa:
66 _____ ___________
*67:
Minnequa part ----
LaPorte part -----
Miracle:
68 _________________
Naz:
69 _________________
70 -----------------
Nelson:
71 _________________
Newfork:
72 _________________
n:
76 -----------------
Otero:
77 -----------------
78, 79 ______________
*80:
Otero part ______-
Nelson part ------
LARIMER COUNTY AREA, COLORADO
TABLE 9. Building site development —Continued
�w Dwellings without Dwellings with Small commercial
:ions basements basements I buildings
Slight
Severe: wetness;
floods; too
clayey.
Severe: wetness;
floods.
Severe: slope;
too clayey.
Moderate: depth
to rock.
Moderate: depth
to rock; slope.
Severe: depth to
rock.
Severe- depthto
rock; slope.
Slight -----------
Severe: slope ___.
Severe: depth to
rock.
Severe: wetness;
small stones;
floods.
Moderate: too
clayey.
Severe:
wetness.
Moderate: frost
action; shrink -
swell.
Severe: wetness;
floods.
Severe: floods;
wetness.
Severe: slope;
shrink -swell.
Slight
Moderate:
slope.
Severe: depth to
rock.
Severe: slope
Slight __________-
Severe: slope ____
Moderate: depth
to rock.
Severe: floods;
wetness.
Severe:
shrink -swell.
Severe:
shrink -swell.
Slight ___________
Slight -------
Slight ___________
Slight ------
Severe: slope ____
Severe: slope
Severe: depthto
Severe: slope
rock; slope.
Moderate: frost
action;
shrink -swell.
Severe: wetness;
floods.
Severe: floods;
wetness.
Severe: slope,
shrink -swell-
depth to rock.
Moderate: depth
to rock.
Moderate: depth
to rock; slope.
Severe: depthto
rock.
Severe: slope;
depth to rock.
Slight -----------
Severe: slope ____
Severe: depth to
rock.
Severe: floods;
wetness.
Moderate: slope;
shrink -swell;
frost action.
Severe: wetness;
floods: corrosive.
Severe: wetness;
floods; corrosive.
139
Local roads and
streets
Severe: low
strength.
Severe: frost
action; wetness;
shrink -swell.
Severe: frost
action; wetness;
shrink -swell.
Severe: slope; Severe: slope;
shrink -swell;
shrink -swell.
corrosive.
Moderate:
Moderate: low
slope.
strength.
Severe: slope ____
Moderate: low
strength; slope.
Severe: depthto
Severe: depth to
rock.
rock.
Severe: slope
Slight __________-
Severe: slope ----
Moderate: depth
to rock; slope;
corrosive.
Severe: floods;
wetness. .
Moderate:
Severe:
shrink -swell.
shrink -swell;
corrosive.
Severe:
Severe:
wetness.
shrink -swell;
corrosive.
Slight ___________
Slight -------
Slight ___________
Moderate:
slope.
Severe: slope ____
Severe: slope
Severe: depth to
Severe: slope
rock; slope.
Severe: slope.
Moderate: frost
action.
Severe: slope.
Moderate: depth
to rock; frost
action.
Severe: floods;
wetness.
Severe: shrink -
swell; low
strength.
Severe: shrink -
swell; low
strength.
Slight.
Slight.
Severe: slope.
Severe: slope.
STEWARTMSSOCIATES
Consulting Engineers and Surveyors
103 S. MELDRUM, FORT COLLINS, CO 80521
PH. 482-9331 FAX 482-9382
By: A"W"`` Date: Z I1 IC0 Client: N(V '�\Oyvls Sheet No. of Z
Project: �JIC c _ I (-Y�i" � ✓t-%,ie A\aAA-iu-N
Subject:
�11
Arm _ I .L'1S AC.
j1cldl�oln a c Sz`� �L �- P rapos�etb Cr�r�s�ruc.�I'on
T = IO nri,\
QIo = o.-Jolt'00)1.05 = ?— .9 4 Cts
Qtco = o .v605mAl .05 = � .51e cis
1-�w E = 5o3q, 35
STEWART&kSSOCIATES
Consulting Engineers and Surveyors
103 S. MELDRUM, FORT COLLINS, CO 80521
PH. 482-9331 FAX 482-9382
By: ryl\ (Yl Date: Z.' f t I,96 Client: 144OL ZAeWklOrvs Sheet No. Z of Z
Project:
Subject:
SO, 1Iwk4
( tco' 7 . She r-!�s
C= 3.LA f-�Vezord�l We,r
14 _ c .s
100 Year
This is to convert % imp. to a C value
100-year
(must insert % imp. and C pervious).
Required detention
ft'
acre-ft.
'C'value
0.7
11988.0
0.2752
'C'1.25
0.875
Area
1.05
acres
Modified
Modified
Release Rate
0.27
M. FATER
D. JUDIS
C. 1.1
5/95
Nov-97
Nov-98
DETENTION
POND SIZING
TIME
TIME
INTENSI
Q 100
Runoff
Release
Required
Required
cum
100 year
Volume
Cum total
Detention
Detention
(mins)
(secs
(in/hr)
(cfs)
(W3)
(ftA3)
ft"3
(ac-ft
0
0
0
0.00
0
0.0
0.0
0.0000
5
300
9.950
9.14
2742.469
81.0
2661.5
0.0611
10
600
7.720
7.09
4255.65
162.0
4093.7
0.0940
15
900
6.520
5.99
5391.225
243.0
5148.2
0.1182
20
1200
5.600
5.15
6174
324.0
5850.0
0.1343
25
1500
4.980
4.58
6863.063
405.0
6458.1
0.1483
30
1800
4.520
4.15
7474.95
486.0
6989.0
0.1604
35
2100
4.080
3.75
7871.85
567.0
7304.9
0.1677
40
2400
3.740
3.44
8246.7
648.0
7598.7
0.1744
45
2700
3.460
3.18
8582.963
729.0
7854.0
0.1803
50
3000
3.230
2.97
8902.688
810.0
8092.7
0.1658
55
3300
3.030
2.78
9186.581
891.0
8295.6
0.1904
60
3600
2.860
2.63
9459.45
972.0
8487.5
0.1948
65
3900
2.720
2.50
9746.1
1053.0
8693,1
0.1996
70
4200
2.590
2.38
9994.163
1134.0
8860.2
0.2034
75
4500
2.480
2.281
10253.25
1215.0
9038.3
0.2075
80
4800
2.380
2.19
10495.8
1296.0
9199.8
0.2112
85
5100
2.290
2.10
10730.08
1377.0
9353.1
0.2147
90
5400
2.210
2.03
10964.36
1458.0
9506.4
0.2182
95
5700
2.130
1.96
11154.54
1539.0
9615.5
0.2207
100
6000
2.060
1.89
11355.75
1620.0
9735.8
0.2235
105
6300
2.000
1.84
11576.25
1701.0
9875.3
0.2267
110
6600
1.940
1.78
11763.68
1782.0
9981.7
0.2291
115
6900
1.890
1.74
11981.42
1863.0
10118.4
0.2323
120
7200
1.840
1.69
12171.6
1944.0
10227.6
0.2348
125
7500
1.790
1.64
j 12334.22
2025.0
10309.2
0.2367
130
7800
1.750
1.611
12540.94
2106.0
10434.9
0.2396
135
8100
1.710
1.57
12726.61
2187.0
10538.E
0.2419
140
8400
1.670
1.53
12888.23
2268.0
10620.21
0.2438
145
8700
1.630
1.50
13028.79
2349.0
10679.81
0.2452
150
9000
1.600
1.47
13230
2430.0
10800.0
0.2479
155
9300
1.570
1.44
13414.67
2511.0
10903.7
0.2503
160
9600
1.540
1.41
13582.8
2592.0
10990.8
0.2523
165
9900
1.510
1.39
13734.39
2673.0
11061.4
0.2539
170
10200
1.480
1.36
13869.45
2754.0
11115.5
0.2552
175
10500
1.450
1.33
13987.97
2835.0
11153.0
0.2560
180
10800
1.420
1.30
14089.95
2916.0
11174.0
0.2565
185
11100
1.400
1.29
14277.38
2997.0
11280.4
0.2590
190
11400
1.380
1.27
14453.78
3078.0
11375.8
0.2612
195
11700
1.360
1.25
14619.15
3159.0
11460.2
0.2631
200
12000
1.340
1.23
14773.5
3240.0
11533.5
0.2648
205
123001
1.320
1.21
14916.83
3321.0
11595.8
0.2662
210
12600
1.300
1.19
15049.13
3402.0
11647.1
0.2674
215
12900
1.280
1.18
15170.4
3483.0
11687.4
0.2683
220
13200
1.260
1.16
15280.65
3564.0
11716.7
0.2690
225
13500
1.240
1.14
15379.88
3645.0
11734.9
0.2694
230
13800
1.220
1.12
15468.08
3726.0
11742.1
0.2696
235
14100
1.210
1.11
15674.79
3807.0
11867.8
0.2724
240
14400
1.200
1.10
1587E
3888.0
11988.0
0.2752
Page 1
Pond Volume
Her Shalom
Elevation Area (tt2) Volume (0) Total Volume (M)
37.8 0
38 1780 119 119
39 11490 5930 6049
40 22850 16848 22897
Total Volume in Ac-Ft 0.53
UM
STEWART$ ASSOCIATES PH. 82-93311RF FAX 482-938OLLINS, CO 80521
Consulting Engineers and Surveyors
By: MM Date: W Client: I-�1,r Om Sheet No. —Lof
Project: 4ctr
Subject: or` -/ 1 ' C% t G �C,C
)Co �l,- wZL > 3q 3S
Dfs:, �-eJ Q--O Z'% c�5
pp. too
S
��VAl.t -cr C �a5a)� o.c.C,a►)�Le�(.4 C�.y�►li - D,3o Gas
P1--a rz
All
Q O,Z7 cSs 0,30 c-�S
N�o G e Kjeeded