HomeMy WebLinkAboutPROSPECT INDUSTRIAL PARK, LOT 32, MIDPOINT SELF-STORAGE - PDP - 28-98B - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORT�7f!
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APPENDIX A
MAPS AND FIGURES
7. REFERENCES
1. City of Fort Collins, "Storm Drainage Design Criteria and Construction Standards"
(SDDCCS), May 1984.
2. "Final Drainage Report for Lot 15, Prospect Industrial Park", March 15, 1999,
Stewart & Associates.
3. "Final Drainage Report for Lots 28 & 29, Prospect Industrial Park", June 23, 1988,
Stewart & Associates.
4. "Prospect East Industrial Overall Drainage Plan", June 1978, Stewart & Associates.
5. Soil Survey of Larimer County Area, Colorado. United States Department of
Agriculture Soil Conservation Service and Forest Service, 1980.
6. Urban Drainage and Flood Control District, "Urban Storm Drainage Criteria
- Manual", Volumes 1 and 2, dated March 1969, and Volume 3, dated September
1992.
Preliminary Drainage and Erosion Control Report Page 10
Midpoint Self -Storage Solutions October 25, 2000
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improvement plans, with base material consisting of 6" coarse aggregate. The contractor will
be responsible for clearing mud tracked onto city streets on a daily basis.
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5.4 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.
5.5 Permanent Stabilization
■ A vegetative cover shall be established within one and one-half years on disturbed areas and
soil `stockpiles not otherwise permanently stabilized. Vegetation shall not be considered
established until a ground cover is achieved which is demonstrated to be mature enough to
control soil erosion to the satisfaction of the City Inspector and to survive severe weather
conditions.
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project will carry the peak flows of Lot 33 when it is developed in the future. The pipe
design for the future development is included in Appendix D of this report.
5. EROSION CONTROL
5.1 Erosion and Sediment Control Measures
Erosion and sedimentation will be controlled on -site by use of inlet filters, silt fences, straw
bale barriers, gravel construction entrances, and seeding and mulch. The measures are
designed to limit the overall sediment yield increase due to construction 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. Straw bale dikes will be placed along
proposed swales. Erosion control effectiveness, rainfall performance calculations and a
construction schedule will be provided with the final report.
5.2 Dust Abatement
' During the performance Hof 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 fiunish 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
Ithese specifications on right-of-way or elsewhere.
5.3 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 approved 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 Sheet 7 of the
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Midpoint Self -Storage Solutions October 25, 2000
4. HYDRAULIC ANALYSIS
4.1 Allowable Street Capacity
The theoretical street and gutter capacity was calculated using Manning's equation for open
channel flow. Allowable gutter flows and maximum street capacities for both the initial and
major storms were estimated and evaluated based on the specifications set forth in the
SDDCCS Manual. At the Northeasterly comer of Lot 32 the 2-year peak runoff rate is 11.7
cfs, which is greater than the capacity of the gutters (9.2 cfs). The peak 100-year runoff rate
is 51.4 cfs, which is less than the capacity of the street cross section, 72.64 cfs, at 6 inches
over crown, which is allowable flow depth in the 100-year storm for a collector street.
Because the 2-year street capacity is being exceeded in the existing condition, flows to the
front of Lot 32 are conveyed in a storm sewer to the existing borrow pond. See the street
capacity calculations in Appendix C for more detailed information.
4.2 Storm Sewer System
For the storm pipe design, the computer program StormCAD, developed by Haestad
Methods, Inc. was used. StormCAD considers whether a storm pipe is under. inlet or outlet
control and if the flow is uniform, varied, or pressurized and applies the appropriate
equations (Manning's, Kutter's, Hazen -Williams, etc). StormCAD also takes into account
tailwater effects and hydraulic losses that are encountered in the storm structures. It
calculates the losses through an inlet or manhole by allowing the user to assign a coefficient
for the equation,
hL = K*(VZ/2g)
Where hL = headloss
K = headloss coefficient
V = average velocity (ft/s)
g = gravitational constant (32.2 ft/sZ)
The storm pipe design was performed for two different scenarios, the first being the runoff
from the site into the borrow pond to the east of Lot 33 and the second being for the ultimate
build -out of Lot 33 just east of our site. This was done to ensure that the system for this
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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 C = t +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:
tt = [1.87(1.1 - CCr)Lo.51/(S)0a3 (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 Cr are as defined previously. -
All hydrologic calculations associated with the sub -basins shown on the attached drainage
plan are included in Appendix B of this report. A summaryof these calculations for the
basins is included in Table 3.1 below.
Table 3.1 Drainage Summary
Design
pbint
r hAary
SWr6asin
Area
(ac)
c(z),
c(10)
C(100)
tc(2)
(rnlN
tc(1q
(nin)
tc(100)
(rrin)
g2)tot
(cfs)
g1o)tot
(cfs)
g10*d
(cte)
DRAINAGE
STFWT ti7E
flEM IRKS
OS-1
7.55
0.47
0.47
0.58
21.7
21.7
21.7
5.4
9.26
23.7
2
OS-2
8.25
0.35
0.35
0.44
21.6
21.6
21.6
4.5
7.67
19.6
1
101
1.35
0.88
0.8B
1.00
al
6.1
5.0
3.2
S43
13.5
F ndAM
3
102
1.76
0.80
0.80
1.00
7.3
7.3
5.0
3.5
6.03
17.5
FtndBM
OS3
17.54
0.30
0.30
0.38
24.4
24.4
24.4
7.6
13.02
33.2
4
1024CS3
19.30
0.35
0.33
0.41
24.4
24.4
24.4
9.2
15.70
40.1
Pm SAde C.epedty
5
103
1.55
0.94
0.94
1.00
11.9
50
5.0
3.0
7.14
15.5
tot 33 daMoped
6
104
0.12
0.74
0.74
0.93
9.8
9.8
5.0
0.2
0.34
1.1
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Runoff from Subbasin 104 is conveyed via sheet and gutter flow to Midpoint Drive
where it will then travel down the gutter of Midpoint Drive to the intersection of Sharp
Point Drive where a drainage ditch will carry the flows into the existing borrow pond
east of the site. The 2-year historic runoff rate for the front portion of Lot 32 is 0.24
cfs. The 2-year release rate for subbasin 104 is 0.20 cfs. Therefore, the flow releasing
onto Midpoint Drive from Lot 32 has decreased.
Runoff from Subbasin OS-1 is conveyed via sheet flow and gutter flow and was
calculated to determine the capacity of Midpoint Drive.
Runoff from Subbasin OS-2 is conveyed via sheet flow and gutter flow to Midpoint
Drive, DP 2. The flow at DP 2 was used to check the capacity of Midpoint Drive.
Runoff from Subbasin OS-3 is conveyed via sheet flow and gutter flow to the existing
trickle pan and Swale which Subbasin 102 will combine with at DP 4. The flow at DP
4 was used to check the capacity of the existing trickle and Swale in the rear of the lot.
3.4 Hydrologic Analysis of the Proposed Drainage Conditions
The Rational Method was used to determine both 2-year and 100-year peak runoff values for
each sub -basin. Runoff coefficients were assigned using Table 3-2 of the SDDCCS Manual.
The Rational Method is given by:
Q = CfCIA (1)
where Q is the maximum rate of runoff in cfs, A is the total area of the basin in acres, C f 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, Ct, is 1.0 for the initial 2-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
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(back of lot) will sheet flow to a proposed water quality pond which will release into an
existing 1' trickle pan and Swale which has a 100 year capacity of 88.8 cfs as designed by
■ James H. Stewart & Associates in June 1978. The rate of runoff at Design Point 4, the
southeasterly corner of Lot 32, is 40.1 cfs, which is less than the trickle pan and Swale
capacity of 88.8 cfs.
3.3 Proposed Drainage Plan
A qualitative summary of the drainage patterns within each sub -basin and at each design
point is provided in the following paragraphs. Discussions of the detailed design of drainage
facilities identified in this section are included in the following sections.
Runoff from Subbasin 101 will be conveyed via sheet flow and gutter flow to the
water quality structure located at Design Point (DP) 1. This storm flow will be
conveyed via storm pipe to the existing borrow pond east of the site
Runoff from Subbasin 102 will be conveyed via sheet flow and gutter flow to a
proposed water quality structure located at.DP 3. Flow will be conveyed from DP 3
via storm pipe and gutter flow to the existing trickle pan and swale in the rear of the
lot. Flow will join that from sub -basin OS-3 and discharge into the existing borrow
pond to the east of the site.
Subbasin 103 encompasses the front of Lot 33, which is owned by the developer of
Midpoint Self -Storage Solutions. Subbasin 103 was delineated and a connection to
the storm sewer was provided for future development of Lot 33. Runoff from
Subbasin 103 in the future will be conveyed via sheet flow and gutter flow to the storm
sewer manhole at DP 5. This storm sewer has been sized to carry developed peak
flows from subbasin 103. From here, flow will be conveyed via 24" storm sewer pipe
to the existing borrow pond east of Lot 33
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detention. The resultant runoff coefficient for the 17.54 acres of rear lot drainage is C=0.30.
The resultant runoff coefficient for the 8.25 acres of front lot drainage is C=0.35.
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 Appendix A.
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 2-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. A detailed description
of the hydrologic analysis is provided in Section 3.4 and Appendix B of this report.
3.21 General Flow Routing
Flows within this site will take the form of overlot, gutter, and pipe flow. The proposed
drainage patterns from the Prospect East Industrial Overall Drainage Plan have been
maintained as much as possible.
Stormwater Detention is not required or provided for Lot 32 because it is in the Poudre River
Basin. A storm sewer system will be designed to carry peak 100-yr flows from the front of
Lot 32 and proposed Lot 33. This system is being provided because Midpoint Drive does
not have capacity to convey the 2-year runoff (see Appendix C).. Water Quality will also
be provided.
The proposed drainage facilities for this site consist of proposed sump inlets, swales and
drainage pipes. The northern portion of the site (front of lot) will sheet flow to a curb cut at
the northeast comer of the lot and into a water quality pond. A proposed storm pipe will then
carry the storm water from the water quality pond at the southeast corner of the site to an
existing borrow pond approximately 350' east of Lot 32. The southern portion of the site
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Midpoint Self -Storage Solutions October 25, 2000
1.4 Design Criteria
■ This report was prepared to meet or exceed the submittal requirements established 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.
1.5 Master Drainage Basin
Midpoint Self -Storage Solutions lies in the Poudre River Drainage Basin. There is no City
of Fort Collins master plan for the Poudre River Drainage Basin and detention is not required
for this basin. However, releases from the site must not cause negative impact to
downstream drainage facilities and adequate conveyance must be shown from this site to a
major drainage outfall.
2. HISTORIC (EXISTING) DRAINAGE
' The historic (existing) flows for Lot 32 consist of the flows from the site and some offsite
flows from the northwest. The drainage pattern for the property is via overland flow in a
southeasterly and northeasterly direction at approximately 1 percent slope. The -site has a
very good ground cover of native grasses and weeds. An existing 1' trickle pan conveys
flows from the back of Lots 24-32 to an existing borrow pond. This trickle pan was designed
by James H. Stewart & Associates and approved in June 1978. Lots 24-31 are upgradient
from Midpoint Self -Storage Solutions (Lot 32). The capacity of the existing trickle pan &
Swale, at Lot 32, for the 100-yr event is 88.8 cfs as calculated by Stewart & Associates. The
front drainage of lots 24-31 are directed to release into Midpoint Drive which in turn
discharges into the same existing borrow pond via a drainage ditch on the south end of the
Midpoint Drive and Sharp Point Drive intersection.
Presently, Lot 32 has 7 lots upstream contributing to these calculations. Of these 7 lots, one
is presently being developed, two remain undeveloped, three have existing development
which have provided on -site detention, and two existing developments have provided no
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1. INTRODUCTION
1.1 Project Description
Midpoint Self -Storage Solutions is a proposed storage facility located on Lot 32 in Prospect
Industrial Park. The site is located in the Poudre River Drainage Basin and contains
approximately 3.23 Acres. The site is zoned I-G, General Industrial. The proposed site is
located at the southwest intersection of Midpoint Drive and Sharp Point Drive. The project
is a portion of Section 20, Township 7 North, Range 68 West of the Sixth Principal
Meridian, in the City of Fort Collins, Larimer County, Colorado. A location map is provided
in Appendix A.
1.2 Existing Site Characteristics
According to the "Soil Survey for Larimer County Area, Colorado" (USDA) soils for onsite
and off site basins include: Caruso loam (22) & Loveland clay loam (64). The Caruso series
consist of deep, poorly drained soils that formed in alluvium. The Loveland series consist
fo deep somewhat poorly drained soils that formed in material weathered from alluvium.
The characteristics of the Caruso clay loam and Loveland clay loam include slow runoff and
slight 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 Midpoint Self Storage
Solutions. 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 is
consistent with the design concepts of the Prospect East Industrial Overall Drainage Plan.
(Stewart & Associates, 1978)
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' Midpoint Self -Storage Solutions October 25, 2000
TABLE OF CONTENTS
PAGE
TRANSMITTAL LETTER............................................................................................................. i
TABLE OF 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................................................................................................................2
1.5
Master Drainage Basin....................................................................................................2
2. HISTORIC (EXISTING) DRAINAGE.........................................................................I.......2
3. LOCAL DEVELOPED DRAINAGE DESIGN...................................................................3
3.1
Method............................................................................................................................3
3.2
General Flow Routing.....................................................................................................3
3.3
Proposed Drainage Plan ..................................................................................................4
3.4
Hydrologic Analysis of the Proposed Drainage Conditions...........................................5
4. HYDRAULIC ANALYSIS....................................................................................................7
4.1
Allowable Street Capacity...............................................................................................7
4.2
Storm Sewer System.......................................................................................................7
5. EROSION CONTROL...........................................................................................................8
5.1
Erosion and Sediment Control Measures........................................................................8
5.2
Dust Abatement...............................................................................................................8
5.3
Tracking Mud on City Streets.........................................................................................8
5.4
Maintenance....................................................................................................................9
5.5
Permanent Stabilization..................................................................................................9
7. REFERENCES.....................................................................................................................10
Appendix A: Maps and Figures
Appendix B: Pond Calculations
Appendix C: Street Capacity Calculations
Appendix D: Pipe and Inlet Calculations
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VICINITY MAP
N.T.S.
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J•R ENGINEERING
A Subsidiary of Westrian
October 25, 2000
Mr. Basil Hamdan
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, CO 80521
RE: Preliminary Drainage and Erosion Control Report for Midpoint Self Storage Solutions.
Dear Basil,
We are pleased to submit to you for your approval, this Preliminary Drainage and Erosion Control
Report for Midpoint Self -Storage Solutions, a zoned I-G, General Industrial, site located in Prospect
Industrial Park. 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
Prepared ,
David Holloway
Design Engineer I
attachments
Reviewed by,
Randall Provencio
Project Manager
2620 East Prospect Road, Suite 190, Fort Collins, CO 80525
970-491-9888 • Fax: 970-491-9984 • w Jrcngineering.com
PRELIMINARY DRAINAGE AND
EROSION CONTROL REPORT
Midpoint Self -Storage Solutions -
Lot 32 Prospect Industrial Park
Prepared for:
DCB Construction Company, Inc.
909 East'62°d Avenue
Denver, Colorado 80216
(303) 287-5525
Prepared by:
JR Engineering
2620 E. Prospect Road, Suite 190
Fort Collins, Colorado 80525
(970) 491-9888
October 25, 2000
Job Number 9287.00
PRELIMINARY DRAINAGE AND
EROSION CONTROL REPORT
Midpoint Self -Storage Solutions -
Lot 32 Prospect Industrial Park
fV
J•R ENGINEERING
A Subsidiary of Westrian