HomeMy WebLinkAboutRIGDEN FARM, 7TH FILING, THE WILLOWS - PDP - 56-98N - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORT-10
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APPENDIX A
MAPS AND FIGURES
8. REFERENCES
1. City of Fort Collins, "Storm Drainage Design Criteria and Construction Standards"
(SDDCCS), May 1984.
2. "Drainage and Erosion Control Report for Rigden Farm Filing One, P.D.P.", JR
Engineering, September 1999.
3. "Drainage and Erosion Control Report for Rigden Farm Filing Six", JR Engineering,
Revised March 28, 2001 and has yet to be approved by the City of Fort Collins.
4. "Final Report for the Hydrologic Model Update for the Foothills Basin Master
Drainage Plan", April 27, 1999, Anderson Consulting Engineers, Inc.
5. "Foothills Basin (Basin G) Drainage Master Plan", February 1981, Resource
Consultants, Inc.
6. "Overall Drainage Plan for the Rigden Farm O.D.P.", JR Engineering, November
1999.
7. Soil Survey of Larimer County Area, Colorado. United States Department of
Agriculture Soil Conservation Service and Forest Service, 1980.
8. Urban Drainage and Flood Control District, "Urban Storm Drainage Criteria
Manual", Volumes 1 and 2, dated March 1969, and Volume 3, dated September
1999.
Drainage and Erosion Control Report Page 14
The Willows at Rigden Farm June 18, 2001
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.
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.
Drainage and Erosion Control Report Page 13
The Willows at Rigden Farm June 18, 2001
The storm pipe design was performed for the ultimate build -out of The Willows at Rigden
Farms and is included in Appendix E of this report. Riprap is provided at the outlet of all
storm pipes. (See Appendix F for calculations.)
5. EROSION CONTROL
5.1 Erosion and Sediment Control Measures
Erosion and sedimentation will be controlled on -site by use of 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 are provided in Appendix F.
5.2 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.
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 the Erosion Control
Drainage and Erosion Control Report Page 12
The Willows at Rigden Farm June 18, 2001
curb or the street crown for local streets. During the major storm, the depth of water over
the crown or curb is limited to six inches. The 2-year storm was used as the minor storm and
the 100-year storm was used as the major storm for street capacity calculations. See the
street capacity calculations in Appendix C for more detailed information.
4.2 Inlet Sizing
Inlets were sized using the computer program UDINLET that was developed by James C.
Y. Guo of the University of Colorado at Denver. Computer output files for the inlet sizing
are provided in Appendix D of this report. Inlets were designed to receive the 100-year peak
flows. All inlet locations and sizes are shown on the Utility Plans for the construction of this
project. All trench drains are Neenah Type R4990 — DX, with a type "P" grate, and are sized
to carry 1.0 cfs of flow from the private driveways. (See Appendix D for trench drain
capacity calculation.)
4.3 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/s2)
Drainage and Erosion Control Report
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Page 11
June 18,2001
n
where Q is the maximum rate of runoff in cfs, A is the total area of the basin in acres, Cf 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, Cf, 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
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
tC=t;+t,
(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 - CCf)Los[/(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. ,
All hydrologic calculations associated with the sub -basins shown on the attached drainage
plan are included in Appendix 13 of this report.
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. During the initial storm, runoff was not allowed to overtop either the
Drainage and Erosion Control Report Page I
The Willows at Rigden Farm June 18, 2001
Runoff from Offsite-basin OS-1, under ultimate conditions, will be conveyed via
overland and gutter flow to the south gutter of Chase Drive. The developed flow of
OS-1 will then be conveyed eastward toward the existing sump inlet at Design Point
4. The existing storm system conveys flows to the south releasing them in Existing
Water Quality Pond 1.
Runoff from Offsite-basin OS-2, under ultimate conditions, will be conveyed via
overland and gutter flow to the west gutter of Kansas Drive. The developed flow of
OS-2 will then be conveyed southward toward the proposed sump inlet at Design Point
17. The proposed storm system conveys flows to the south releasing them in existing
Water Quality Pond 2.
Runoff from Offsite-basin OS-3, under ultimate conditions, will be conveyed via
overland and gutter flow to the proposed area inlet at design point 1. The developed
flow of OS-3 will then be conveyed southward via pipe flow to existing Water Quality
Pond 2.
Offsite-basin OS-4 is Basin,108 from "Final Drainage and Erosion Control Report for
Rigden Farm Filing One, P.D.P." This basin picks up a carryover of 4.42 cfs from
Design Point R8c and 6.60 cfs of carryover from Design Point R7e. The existing
sump inlet on Custer Drive captures these flows and routes them to the existing Water
Quality Pond 1 via storm pipe. The revised flows to the existing sump inlet were
checked and do not show any negative impacts to the inlet or the pipe system installed
with Rigden Farm First Filing. (See calculations in Appendix E.)
3.4 Hydrologic Analysis of the Proposed Drainage Conditions
The Rational Method was used to determine the 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 = CrCIA
Drainage and Erosion Control Report
The Willows at Rigden Farm
(1)
Page S
June 18, 2001
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the pipe flow software and the system was still capable of handling the flows
comfortably. (See Appendix D for grate calculation)
Runoff from Sub -basin 120a, 120b, 120c, and 120d will flow to on -grade trench
drains at Design Points 30, 31, 32 and 33 respectively. A concrete chase will carry
each of these flows eastward to Kansas Drive. These Sub -basins all contribute to the
flow at Design Point 17 which joins the flow of DP 16 before entering the proposed
sump inlet. The pipe system will then carry these flows to south releasing them into
the existing Water Quality Pond 2.
Runoff from Sub -basin 121 will be conveyed via gutter flow to Design Point 16.
Flows from Design Point 16 will join that of Design Point 17 before entering a
proposed sump inlet and pipe system, which conveys flows to the existing Water
Quality Pond 2.
Runoff from Sub -basin 122 will be conveyed via gutter flow to a proposed sump inlet
at Design Point 10. Flows from Design Point 10 will join that of Design Point 8
before entering a proposed sump inlet and pipe system, which conveys flows to the
existing Water Quality Pond 1.
Runoff from Sub -basin 123 will be conveyed via gutter flow to a proposed sump inlet
at Design Point 8. Flows from Design Point 8 will join that of Design Point 10 before
entering a proposed sump inlet and pipe system, which conveys flows to the existing
Water QualityPond 1.
Runoff from Sub -basin 124 will be conveyed via gutter flow to a proposed on -grade
combination inlet at Design Point 22. Flow will then enter a storm sewer system,
which conveys flows to the existing Water Quality Pond 1.
Runoff from Sub -basin 125 will be conveyed via overland flow, directly into Existing
Water Quality Pond 1 designed with Rigden Farm Filing One P.D.P.
Runoff from Sub -basin 126 will be conveyed via overland flow, directly into Existing
Water Quality Pond 2 designed with Rigden Farm Filing One P.D.P.
Drainage and Erosion Control Report
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Page 8
June 18, 2001
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18 before entering the proposed sump inlet. These flows are then conveyed via pipe
flow to the existing Water Quality Pond 2.
Runoff from Sub -basin 115b flow southeastward to Design Point 27. Flow is released
onto proposed Parkside Drive and conveyed to the proposed sump inlet at Design
Point 18. The flows will then be conveyed to the south via pipe flow to the existing
Water Quality Pond 2.
Runoff from Sub -basins 115c & 115d flows westward to Design Points 28 and 29,
respectively and into proposed trench drains. These trench drains release into concrete
chases which in turn release on to Kansas Drive. The flow from each of these Sub -
basins is conveyed along the easterly gutter of Kansas Drive to the proposed sump inlet
at DP 18 & DP 15. After entering the sump inlet, flows are then conveyed via pipe
flow to the existing Water Quality Pond 2.
Runoff from Sub -basin 116 is conveyed via overland and gutter flow to Design Point
15, a proposed sump inlet. The flow joins that of DP 18 and the other Sub -basins
contributing to DP 15 before entering the sump inlet. The flow is then conveyed via
storm pipe to the existing Water Quality Pond 2.
Runoff from Sub -basin 117 will be conveyed via overland and swale flow to a curb
cut at Design Point 19. Flow will then be conveyed along the northern gutter of
Parkside Drive eventually joining the remaining flows contributing to DP 18 & 15
before entering the proposed storm sewer.
Runoff from Sub -basin 118 ultimately will be conveyed via overland flow eastward
toward Kansas Drive. Flow will then be conveyed via gutter flow toward design point
17 where it will join the remaining flows contributing to DP 17 and also join those of
DP 16 before entering the proposed sump inlet on Parkside Drive. The storm system
releases into the Water Quality Pond 2.
Runoff from Sub -basin 119 will be conveyed via swale flow to design point 20 where
an existing manhole lid will be replaced by an open grate. The revised flows to this
manhole and pipe pose no negative impacts. The inlet capacity check was re -run with
Drainage and Erosion Control Report
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June 18,2001
turn releases on to Parkside Drive where it joins the flows from DP 9 & DP 7 and
enters the proposed sump inlet. These flows are then conveyed via pipe flow to the
existing Water Quality Pond 1.
Runoff from Sub -basin 111 is conveyed via overland and gutter flow to Design Point
11, an on -grade trench drain. The trench drain releases into a concrete chase which in
turn releases on to Parkside Drive where it joins the flows from DP 9 & DP 7 and
enters the proposed sump inlet. These flows are then conveyed via pipe flow to the
existing Water Quality Pond 1.
Runoff from Sub -basin 112 will be conveyed via overland and gutter flow southward
to Design Point 13 and then flow easterly to the proposed sump inlet eventually
joining with the remaining flows at DP 7 & DP 9. The pipe system will carry the
flows to the existing water quality ponds to the south.
Runoff from Sub -basin 113 will be conveyed southward to Design Point 14 via
overland and gutter. From here, the flows will follow the north flowline of Parkside
Drive to Design Point 15. The flow at Design Point 15 will join that of Design Point
18 and enter the proposed sump inlet. The flow will then be conveyed via storm pipe
southward to the existing Water Quality Pond 2.
Runoff from Sub -basin 114 will be conveyed via overland and Swale flow to a curb
cut at Design Point 12. Flow will then be conveyed along the western side of
Parkfront Drive, eventually joining the remaining flows from DP 15 & DP 18, before
entering the proposed storm sewer.
Runoff from Sub -basin 115 is conveyed via overland and gutter flow to Design Point
18, a proposed sump inlet. The flow joins that of DP 15 and the other Sub -basins
contributing to DP 18 before entering the sump inlet. The flow is then conveyed via
storm pipe to the existing Water Quality Pond 2
Runoff from Sub -basin 115a is conveyed via overland and gutter flow to Design Point
26, an on -grade trench drain. The trench drain releases into a concrete chase which in
turn releases on to Parkside Drive where it joins the remaining flows from DP 15 & DP
Drainage and Erosion Control Report Page 6
The Willows at Rigden Farm June 18, 2001
Inlet (DP 18) designed with the `Final Drainage and Erosion Control Report for
Rigden Farm Filing Six", which is still awaiting city approval. The revised flows to
the proposed sump inlet were checked and do not show any negative impacts to the
inlet or the pipe system installed with Rigden Farm First Filing. (See Appendix D for
the revised inlet capacity calculation.)
Runoff from Sub -basin 106a will be conveyed via overland flow directly on to Rigden
Parkway. A flow of 1.6 cfs will be released onto Rigden Parkway and picked up by
the proposed 10' Type R Inlet (DP 18) designed with the "Final Drainage and Erosion
Control Report for Rigden Farm Filing Six", which is still awaiting city approval
Runoff from Sub -basin 107 will flow southward to Design Point 5. Flow is release
onto the proposed Parkside Drive and conveyed to the on -grade combination inlet at
Design Point 21. The flows will then be conveyed to the south via pipe flow to the
existing Water Quality Pond 1.
Runoff from Sub -basin 108 will flow westward and then southward to design point
6. An on -grade trench drain will pick up this flow and direct it to a concrete chase
which will outlet on the north flowline of Parkside Drive. The flows will follow the
north gutter of Parkside Drive to the west, to the proposed sump inlet at Design Point
7. The flows will be conveyed via storm pipe southward to the existing Water Quality
Pond 1.
Runoff from Sub -basin 109 will be conveyed via overland and gutter flow to a sump
inlet, at Design Point 7. The flow will then be carried via pipe flow to the existing
Water Quality Pond 1.
Runoff from Sub -basin 110 is conveyed via overland and gutter flow to design point
9, a proposed sump inlet in Parkside Drive. These flows are joined by those flows
from Design Point 7 and conveyed via pipe flow to the existing Water Quality Pond
1.
Runoff from Sub -basin 110a is conveyed via overland and gutter flow to Design Point
23, an on -grade trench drain. The trench drain releases into a concrete chase which in
Drainage and Erosion Control Report Page 5
The Willows at Rigden Farm June 18, 2001
Runoff from Sub -basin 100 will be conveyed via overland and gutter flow eastward
to design point 4 on Custer Drive, where an existing sump inlet will ultimately convey
these flows south to the existing Water Quality Pond 1.
Runoff from Sub -basin 101 will be conveyed via overland flow to design point 1,
where a sump inlet will ultimately convey these flows to the existing Water Quality
Pond 1.
Runoff from Sub -basin 102 will flow along the western gutter of Willow Drive to
design point 2, where gutter flow will carry the flows east to an existing sump inlet on
Custer Drive (Design Point 4). These flows are to be ultimately conveyed to the
existing Water Quality Pond 1 designed with Rigden Farm Filing One P.D.P. The
revised flows to the existing sump inlet were checked and do not show any negative
impacts to the inlet or the pipe system installed with Rigden Farm First Filing. (See
calculations in Appendix E.)
Runoff from Sub -basin 102a will flow east to the western gutter of Parkfront Drive
to design point 2, where gutter flow will carry the flows east to an existing sump inlet
on Custer Drive (Design Point 4). These flows are to be ultimately conveyed to the
existing Water Quality Pond 1 designed with Rigden Farm Filing One P.D.P
Runoff from Sub -basin 103 will flow along the eastern gutter of Parkfront Drive to
Design Point 3. From here, the southern gutter of Chase Drive will carry flows to the
existing sump inlet (DP 4) and ultimately to the existing Water Quality Pond 1.
Runoff from Sub -basin 104 and 105 will be conveyed along the southern side of
Chase Drive to Design Point 4 and into the existing sump inlet. The flows will be
carved via pipe flow to the existing water quality ponds.
Runoff from Sub -basin 106 will be conveyed via overland and gutter flow the north
gutter of proposed Parkside Drive to a proposed on -grade combination inlet (DP 21),
which outlets to the south into the existing Water Quality Pond 1. A carryover of 0.24
cfs will be released onto Rigden Parkway and picked up by the proposed 10' Type R
Drainage and Erosion Control Report
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Page 4
June 18, 2001
U
Control Report for Rigden Farm Filing One, P.D.P." addressed the historic quantities and
routing of storm water within The Willows development and therefore, historic runoff
calculations are not included as part of this report.
3. LOCAL DEVELOPED DRAINAGE DESIGN
3.1 Method
The Rational Method was used to determine the 2-year and 100-year flows 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
the calculations are found in Appendix B of this report.
3.2 General Flow Routing
The proposed drainage patterns from the Overall Drainage Plan for the Rigden Farm O.D.P.
have been maintained as closely as possible with this development. Flows within this site
will take the form of overlot, gutter, swale and pipe flow. The proposed drainage facilities
for this site consist of proposed sump inlets, swales, sidewalk chases, drainage pipes, and
erosion control. The following summarizes proposed flow routing within the site. The
Overall Drainage Plan,, attached in the map pocket, depicts the locations of basins, design
points, and proposed storm sewer.
Runoff from the parcel will be conveyed to the south where it will then be collected by a
number of inlets and storm pipe, along proposed Parkside Drive. From here, the storm pipes
outlet into Water Quality Ponds 1 & 2, designed with Rigden Farm Filing One P.D.P.
1 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. Certain sub -basins are combined for
discussion purposes where practicable, and discussed relative to the design point to which
the sub -basins drain. Discussions of the detailed design methodologies for the drainage
facilities identified in this section are included in the following sections.
Drainage and Erosion Control Report Page 3
The Willows at Rigden Farm June 18, 2001
1 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 1969 and 1991, developed by the Denver Regional
Council of Governments have been utilized.
1.5 Master Drainage Basin
The Willows at Rigden Farms lies in Reach 2 of the Foothills Drainage Basin.
The master drainage basin study for this area is the "Foothills Basin (Basin G) Master
Drainage Plan" by Resource Consultants, Inc., 1981. Another applicable report is the "Final
Report for Hydrologic Model Update for the Foothills Basin Master Drainage Plan" by
Anderson Consulting Engineers, Inc. (ACE) dated July 15, 1999. The proposed site is also
included in the "Overall Drainage Plan for Rigden Farm O.D.P." by JR Engineering, dated
November 24, 1999. The ACE model incorporates the proposed build out of the Rigden
Farm subdivision as defined in the O.D.P. report.
2. HISTORIC (EXISTING) DRAINAGE
The historic (existing) flows draining to or through the site consist primarily of on -site flows
with some off -site flows. The overall drainage pattern for the entire site is via overland flow
in a southerly direction at slopes that range from 0.5 to 10 percent. The site currently drains
directly into Water Quality Ponds 1 & 2 designed with the "Final Drainage and Erosion
Control Report for Rigden Farm Filing One, P.D.P." These Water Quality Ponds outlet
directly into the Foothills Regional Channel. The most recent HEC-2 hydraulic model for
the Foothills Regional Channel was developed by ACE in 1995 and was revised in 1999 to
reflect the new 3.67" 100-year rainfall discharges. The latest ACE model (file name
FHBRC99.dat dated 7/18/99) was converted to HEC-RAS for the Overall Drainage Plan for
the Rigden Farm O.D.P. (file name Foot6.prj). The HEC-RAS for the O.D.P. was modified
to reflect proposed improvements for Rigden II, which is awaiting city approval. The
"Overall Drainage Plan for the Rigden Farm O.D.P." and the "Final Drainage and Erosion
Drainage and Erosion Control Report Page 2
The Willows at Rigden Farm June 18, 2001
1. INTRODUCTION
1.1 Project Description
The Willows at Rigden Farm is located in the north half of Section 29, Township 7 North,
Range 68 West, City of Fort Collins, Larimer County, Colorado. The Willows is shown as
Tract D on Rigden Farm Filing One Final Plat. A location map is provided in Appendix A.
The site is bound by Custer Drive to the north, Water Quality Ponds 1 & 2 (from Rigden
Farm Filing One P.D.P.) to the south, Rigden Parkway to the east and, the soon to be,
Timberline Church site to the west.
1.2 Existing Site Characteristics
The site is primarily covered with native grasses. The parcel currently drains in a southerly
direction at slopes ranging from 0.5% to 3%. The site discharges into Water Quality Ponds
1 & 2 designed in Rigden Farm Filing One P.D.P. documents. The soil is predominately
Nunn clay loam (soil numbers 73 and 74) having slopes from 0 to 5% as shown on the soil
map included in Appendix A (USDA SCS, 1980). Nunn clay loam consists of nearly level
soils on high terraces and fans. Pertinent characteristics of this soil include slow to medium
runoff, a slight hazard of wind erosion, and a moderate hazard of water erosion. Nunn clay
loam is categorized as Hydrologic Group C. The other soil group found in the site area in
limited amounts is Fort Collins Loam (soil number 36). Runoff from the Fort Collins Loam
is moderate, and the hazards of wind and water erosion are moderate.
1.3 Purpose and Scope of Report
This report defines the proposed drainage and erosion control plan for Rigden II. The plan
includes consideration of all on -site and tributary off -site runoff and the design of all
drainage facilities required for these streets, lots, and open spaces. This drainage plan is
consistent with the design concepts of the drainage report prepared for Rigden Farm Overall
Development Plan (O.D.P.) and with the design concepts of the Drainage and Erosion
Control Report for Rigden Farm Filing One, P.D.P. (PDP).
Drainage and Erosion Control Report Page 1
The Willows at Rigden Farm June 18, 2001
I-
TABLE OF CONTENTS
PAGE
TRANSMITTALLETTER.................................................................................. 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................................................................................................................2
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.....................................................................................................3
3.3 Proposed Drainage Plan ..................................................................................................3
3.4 Hydrologic Analysis of the Proposed Drainage Conditions...........................................9
4. HYDRAULIC ANALYSIS..................................................................................................10
4.1 Allowable Street Capacity .............................................................................................10
4.2 Inlet Sizing....................................................................................................................11
4.3 Storm Sewer System.....................................................................................................I I
5. EROSION CONTROL.........................................................................................................12
5.1 Erosion and Sediment Control Measures......................................................................12
5.2 Dust Abatement.............................................................................................................12
5.3 Tracking Mud on City Streets.......................................................................................12
5.4 Maintenance..................................................................................................................13
5.5 Permanent Stabilization................................................................................................13
8. REFERENCES ...................................
Appendix A: Maps and Figures
Appendix B: Hydrologic Calculations
Appendix C: Street Capacity Calculations
Appendix D:"Inlet Calculations
Appendix E: Storm Pipe and Swale Calculations
Appendix F: Erosion Control
Appendix G: Excerpts from Other Reports
Drainage and Erosion Control Report
The Willows at Rigden Farm
.....................................................14
June 18, 2001
4
FINAL DRAINAGE AND
EROSION CONTROL REPORT
The Willows at Rigden Farm
Prepared for:
Slayt Construction
215 Union Boulevard, Suite 350
Lakewood, Colorado 80228
(303) 989-2026
Prepared by:
JR Engineering
2620 E. Prospect Road, Suite 190
Fort Collins, Colorado 80525
(970) 491-9888
June 18, 2001
Job Number 9304.00
Drainage and Erosion Control Report
The Willows at Rigden Farm
June 18, 2001