HomeMy WebLinkAboutDAKOTA RIDGE PUD FIRST FILING FINAL - 60 91E - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTNo Text
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DRAINAGE SCHEMATIC
FIGURE 2
2. Tract "A" 4.81 Acres
3. West one-half Road "A" 0.37 Acres
(Horsetooth North 600')
Total 6.05 Acres
Flows in Basin A are calculated to reflect the proposed runoff from Tract "A" as if it
were developed. Flows in this basin will flow along the west curb line in Road "A" and into
Retention Pond "A". This retention pond will become a detention pond when the school site
is ultimately developed.
Basin "B"
Basin "B" includes the back yard drainage of the easterly lots, culd-de-sac A,
a portion of cul-de-sac "B" and the north one-half of Horsetooth road from Road "A"
to the east boundary as follows:
1. Back Yards (Grassed)
2. North One -Half of Horsetooth Road
(Road "A" to eastern boundary)
Total
7.50 Acres
0.63 Acres
8.13 Acres
Horsetooth runoff will be diverted by a curb chase at the eastern property line and
conveyed via a concrete lined swale to detention Pond "C". This concrete lined swale
will also intercept sheet runoff from back yards and keep these flows running offsite.
Basin "C"
Basin "C" includes the lots adjacent to the remaining east -west running cul-de-
sacs and the adjacent east one-half of Road "A". Flows from the cul-de-sacs run west
to
Road "A" and then north to a curb inlet. A concrete lined swale diverts the runoff
from the street to detention Pond "C". Approximately 6.01 acres contribute runoff in
this area.
Basin "D"
The remaining lots north of the 36" storm sewer line including the east one-half j
of Road "A" and Road "B" are included in Basin "D". This area includes 5.20 acres
and drains along Roads "A" & "B" to detention Pond "C". f
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Basin "E"
A 1370 feet length of the west one-half of Road "A" will drain to an inlet at the
intersection of Road "A" and Road "B". This runoff will be directed to Retention Pond
"B". This area includes 0.85 acres.
BASIN SUMMARY
BASIN
AREA
HIST.
Q2
HIST.
Q100
DEVEL.
Q2
DEVEL.
0100
DETEN.
RETEN.
REQUIRED
ACRES
CFS
CFS
CFS
CFS
FT
A
6.05
2.64
9.23
4.19
14.63
1 45,360
B
8.13
5.74
20.21
96,930
C
6.01
2.40
8.22
4.46
15.72
D
5.20
3.98
14.04
E
0.85
0.13
0.55
1.64
5.84
18,036
TOTAL
26.24
5.17
18.00
20.01
70.44
MR
14
Erosion Control
This project is located in an area designated by the City of Fort Collins as having
moderate potential for both wind and water erosion. This 26.24 acre project will be
developed in one phase during the late summer and fall of 1992. A summary of the
improvements necessary to minimize erosion follows:
Wind Erosion
This property is typically barren ground through the winter months when wind
erosion is the most severe. The construction of improvements in this area will provide
an area less likely to experience wind erosion than the surrounding area.
Water Erosion
A series of curbs and concrete swales will keep runoff controlled on -site. These
flows will be routed to temporary retention and detention ponds at various locations.
These facilities will also act as, sedimentation traps during the construction process.
M
F
Conclusions and Recommendations
The development of 66 single family lots will be the initial construction effort in the
Pinecone Overall Development plan. As such, the drainage system is designed to
accommodate this proposed project and function within the overall system. A summary of
the design concepts and proposed improvements which will accomplish that goal follows:
1 . The individual lots drain towards the street.
2. Curbed streets and concrete swales convey runoff to retention and detention
facilities.
3. Off -site flows are conveyed through the site to retention and detention
ponds.
4: Back lot swales are .concrete lined and prohibit water from running off -site.
5. Temporary retention ponds A & B will retain runoff from Basins A & E. These
ponds will be replaced by detention ponds to be built as part of the school site.
Ultimately these ponds will discharge into a 36" outlet pipe.
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144
6. Temporary detention pond "C" will detain flows from Basins B, C & D. This
pond will outlet into an existing concrete lined swale. This pond will be
eliminated when Phase II of Pincone is constructed and the permanent
detention pond is built.
7. This site is not located within an established floodway or floodplain.
8. The general drainage patterns for this area will remain intact.
9. The existing irrigation ditch along Horsetooth Road will be relocated and placed
in a pipe.
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FINAL DRAINAGE &
EROSION CONTROL REPORT
FOR
DAKOTA RIDGE P.U.D. FIRST FILING
(NORTH SIDE OF HORSETOOTH ROAD
EAST OF TIMBERLINE ROAD)
PREPARED FOR:
CDL PARTNERSHIP
DICK PITNER
CHUCK BETTERS
LARRY O'DAU
FORT COLLINS, COLORADO
MAY 4, 1992
(REVISED MAY 26, 1992)
PREPARED BY:
PARSONS & ASSOCIATES
CONSULTING ENGINEERS
432 LINK LANE PLAZA
FORT COLLINS, COLORADO 80524
(303) 221-2400
PROJECT NUMBER: 92.08 PIN
TABLE OF CONTENTS
Introduction
Site Description
Historic Drainage
Master Drainage
Drainage Criteria
Drainage Under Developed Conditions
Erosion Control
Conclusions and Recommendations
Calculations
Grading and Drainage Plan
Figure 1 Vicinity Map
Figure 2 Drainage Schematic
I
FINAL DRAINAGE &
EROSION CONTROL REPORT
FOR
DAKOTA RIDGE P.U.D. FIRST FILING
FORT COLLINS, COLORADO
Introduction
This drainage report has been prepared along with final engineering drawings to provide
design information for the development of 66 single family residences along the north side of
Horsetooth Road just east of its intersection with Arctic Fox Drive. This report was prepared
in conformance with the City of Fort Collins "Storm Drainage Design Criteria and Construction
Standards" and in conformance with the Master Drainage Study prepared as part of the
Pinecone Overall Development Plan.
Site Description
This study area is located in the Southwest Quarter of Section 29, Township 7 North,
Range 69 West of the 6`h Principal Meridian, City of Fort Collins, Larimer County, Colorado
(see Figure 1.) This site, to be developed as Pinecone P.U.D.First Filing, is a 26.24 acre
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11 PROJECT SITE
VICINITY MAP
N.T.S.
FIGURE
parcel designated as planning areas F, G, and H, in the recently approved Pinecone Overall
Development Plan (ODP). This project will be the first development to take place within the
Pinecone ODP. The initial construction will provide for 66 single family residential tracts. A
4.81 acre parcel identified as Tract "A" will remain vacant at this time. Tract "A" will be
developed as a residential development with a proposed density of 7-8 D.U./Acre in the
future.
The southerly boundary of this project is adjacent to Horsetooth Road and the Fox
Meadows Subdivision. The remaining three sides are surrounded by vacant farm ground.
These adjacent areas are proposed for development and are currently under review by the City
of Fort Collins. The north and west boundaries are adjacent to areas currently being
considered as part of the Pinecone Overal► Development Plan. The westerly area will be the
site of the new Fort Collins High School and the northerly area will contain single family
residences similar in density to the Pinecone P.U.D. First Filing. The eastern boundary is
adjacent to the Webster Farm. Development plans for the Webster Farm call for residential
development with a slightly higher density adjacent to the Pinecone P.U.D. transitioning to
larger single family lots.
The site has been used as irrigated farm ground and planted with various crops. The
fields are typically bare from October through May. Surface drainage and site irrigation flow
from southwest to northeast. Grades approach one percent at the southwest corner of the
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site and become flat at the eastern edge of the property.
Historic Drainage
Although no development or drainage improvements exist on the site currently,
drainage patterns are controlled by adjacent streets and the irrigation ditches on the site.
Horsetooth Road provides a drainage barrier from runoff to the south. Flows from Horsetooth
Road and from the Fox Meadows Subdivision are directed to a detention pond at the
southwest corner of Caribou Road and Horsetooth Road. The existing centerline crown of
Horsetooth Road and curb and gutter along Horsetooth Road on the south side appear to be
effective in diverting runoff to this detention pond.
Timberline Road intercepts runoff from the development to the west and diverts these
flows to the Foothills Basin drainage facilities to the north of this site. The centerline of
Timberline Road and the curb and gutter along the west side of the roadway insure that runoff
is diverted to the north.
The runoff to the east on The Webster Farm runs away from this site. Runoff from
areas to the north also run away from this site. Existing irrigation ditches and collection
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ditches tend to collect runoff and direct flows to the east. These irrigation ditches will be
removed as development progresses and drainage flows will be routed through the proposed
street and drainage systems.
Master Drainage
The Pinecone Overall Development Plan Drainage Study identifies drainage basins and
storm water facilities for the entire Pinecone Development. At the heart of this plan is a 36"
outfall line which will convey stormwater from proposed detention ponds. Two major
affect this project. The first po
nd area Pond
detention and locations are identified whichP 1 P
p
213) collects water from the 70 acre school site to the west and from the Pinecone P.U.D
First Filing west of Road "A". The second pond area (Pond 214) is proposed to be located
I
i
at the southeast corner of the overall Pinecone site and will provide detention for the
jremaining 100 acres of single family residential development. Both of these ponds will
discharge into the proposed 36" outfall line which will convey historic runoff to the Fossil
Creek Ditch approximately one -quarter mile to the east. The Dakota Ridge P.U.D. First Filing
drainage system was designed to be in conformance with these guidelines.
ME
Drainage Criteria
The rational Formula was used to develop flows for this project. The Rational Formula
is an excellent predictor of runoff in basins less than 200 acres. Manning's formula was used
to determine the capacities of channels, curb sections and pipes.
Drainage Under Developed Conditions
The development of 66 single family residential lots and associated streets will create
five drainage basins (see figure 2). Flows from these basins are directed to retention and
detention facilities via streets or swales depending on their location. A summary of these
basins follows:
Basin "A"
Basin "A" is the area west of the main entrance Road "A". This area includes:
1. North one-half of Horsetooth Road 0.87 Acres
(School Parking Lot Drive at Arctic Fox to Road "A")
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