HomeMy WebLinkAboutREGISTRY RIDGE PUD, PHASE I - FINAL - 32-95B - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTRegistry Ridge P.U.D. Page 8
Final Drainage Report
APPENDIX
PAGE
SWMMModeling..........................................................
Al- A23
On -Site Hyrology..........................................................
B1- B21
Street Capacity..........................................................
C1- C20
Designof Inlets..........................................................
D1- D44
Design of Swales..........................................................
E1- E42
Design of Culverts..........................................................
Fi- F21
Design of Storm Sewers ...............................................
G1- G65
Detention Pond Rating Curves .....................................
H1- H10
YI
Registry Ridge P.U.D. Page 7
Final Drainage Report
REFERENCES
Preliminary Drainage Report for Registry Ridge P U.D., Fort
Collins, Colorado, Northern Engineering Services, Inc.,
October 4, 1995.
2. Fossil Creek Drainage Basin Master Drainagewav Planning
Study, City Of Fort Collins, Simons, Li & Associates, Inc.,
August 1982.
3. Storm Drainage Design Criteria and Construction
Standards, City of Fort Collins, Colorado, May, 1984.
4. Drainage Criteria Maunal, Urban Drainage and Flood
Control District, Wright -McLaughlin Engineers, Denver,
Colorado, March, 1969.
to
tRegistry Ridge P.U.D. Page 6
Final Drainage Report
under Shields Street will be required, the Off -Site Storm Sewer Line and Culvert 603.
Runoff from Basin 404 is routed undetained to Lang Gulch and runoff from Basins' 405
and 406 is routed to Pond 605 and released directly to Lang Gulch.
The streets adjacent to Registry Ridge P.U.D. (Shields Street on the east and
Trilby Road on the north) have been designed for both an "Interim" and "Future"
Condition. Plans for the street design can be found in the set, "Utility Plans for Registry
Ridge P.U.D. Off -Site Arterial Street Improvements" by Northern Engineering Services,
Inc., submitted to the City of Fort Collins on June 24, 1996. The storm drainage system
for the streets has also been designed for both "Interim" and "Future" conditions. Plans
' and supporting calculations for the storm drainage improvements can be found in the set
"Utility Plans for Registry Ridge P.U.D." by Northern Engineering Services, Inc..
V. EROSION CONTROL
5.1 Erosion Control Plan
Permanent riprap will be provided at the outlet of all culverts. Grass -lined swales
shall be seeded immediately upon completion with the permanent seed mix specified on
the Grading Plan.
Temporary sediment control consisting of straw bale dikes will be used in swales
until permanent vegetation is established. Gravel filters will be required at all curb inlets
and silt fencing installed adjacent to ponds and drainageways.
VI. CONCLUSIONS
6.1 Compliance with Standards
All drainage analyses have been performed according to the City of Fort Collins
Storm Drainage Design Criteria Manual (SDDCM) and the Urban Drainage and Flood
Control District's Drainage Criteria Manual.
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Registry Ridge P.U.D. Page 5
Final Drainage Report
Onsite are newly recontoured/designed facilities one releasing to Smith Gulch
(Pond 601) and the second releasing to Lange Gulch (Pond 605). Pond 601 is using the
original Trilby Road pipe crossing while Pond 605 is a completely new design. All rating
cures have been developed with existing outlet conditions and modified grading where
applicable, or the design grading and outlets structures proposed. Please reference the
following table for a summary of basin constants and conveyance element modifications
and/or inclusions.
The consequence of development of Registry Ridge has minimal impact to offsite
adjacent and downstream property owners. The use of onsite detention and improvement
to offsite developer owned historic detention ponds are a necessity. These facilities are
being built and improved as design requirements dictate to ensure proper downstream
security.
4.4 Hydraulic Criteria
The City 'of Fort Collins Storm Drainage Design Criteria has been referenced for
all hydraulic calculations. In addition, the following computer programs have been
utilized:
• The computer program "HY8" by the U.S. Department of
Transportation, Federal Highway Administration has been used to
size all culvert crossing,
• The computer program "UDINLET" has been used to analyze inlet
capacities,
• The computer program "Flowmaster" has been used to analyze the
capacity of proposed swales,
4.5 Drainage Concept
Detention is not a requirement within the Fossil Creek Major Drainage Basin. The
developer of Registry Ridge however, desires to incorporate both on and off -site detention
1 facilities into the drainage system to provide a water quality mechanism as well as negate
the possibility of further bank erosion along Lang Gulch and Smith Creek.
Developed stormwater will be conveyed through the streets and proposed on -site
stormwater sewer system to swales and either an on -site or off -site detention facility.
The site is divided into six (6) major drainage basins 401-406. Developed
stormwater runoff from Basin 401 is routed to proposed Pond 601 and released to Smith
Creek Tributary. Downstream property owners have been contacted in order to
coordinate the necessary downstream easements and potential improvements.
Runoff from Basins' 402 and 403 is routed off -site to Pond 303. Two (2) crossings
Registry Ridge P.U.D. Page 4
Final Drainage Report
100 year SWMM model for Fossil Creek, written as part the Fossil Creek Master Plan,
was also used to model the effects of the Registry Ridge Development on the overall
master plan.
The modeling revisions for the project area are based on, and included in the
original Fossil Creek Drainage Basin Master Drainageway Planning Study (the Master
Plan), prepared by Simons & Li Associates circa 1982. The project resides on the western
most reaches of the regional master plan on Lange and Smith Gulch's. Hydraulic
connections are made west of South Shields Street, or south of Trilby Road. Original
basin constants have been used with only inclusions of developed basins and elements
rather than modification to the original "developed condition" parameters used. All
modeling revisions meet the accepted standards required by the City of Fort Collins
Stormwater Utility and/or the applicable SDDCCS design requirements. The UDSWMM
version used for this design is the program MODSWMM developed for Urban Storm
Drainage and considered the standard for the City of Fort Collins. The MODSWMM run
was undertaken to clarify any downstream impacts and for the sizing and recontouring
of detention ponds influenced by this development.
Basin hydrologic conditions in this macro analysis are shown in the accompanying
table with a total of six developed basins shown. This number is consistent with the
preliminary report presented in October 1995. Refinements of those individual basins from
the grading plan and actual impervious conditions are now part of this final design model.
Additionally, embedded basin elements are now shown for each of the seven developed
basin identified. Lengths and slopes are based on the averages for the individual sub -
basins within the major seven areas. A spreadsheet was developed that establishes the
averages and the major basins widths to be included in the model. A copy of this data
is included as part of the report for your use.
Existing pipes have not been modified at the two pipes crossing of Trilby, the
single Shields pipe nor the two Colorado and Southern Railroad (CSR crossing) pipe
crossing east of the project area. One new Shields Street crossing is included, that
connects to the existing pond 302 offsite. Naturally occurring ponding is indicated in the
original Master Plan and in the revisions presented. Ponding historically occurs at the
upstream end of the existing Shields Street crossings (Ponds 301), the CSR crossing
(Pond 302), the easterly Trilby crossing (Pond 303) and the westerly crossing of Trilby
(Pond 601). Three of the historic ponds 302, 303 & 601 are part of the Developers
property, while only one naturally occurring pond, Pond 301 resided offsite. All pond
facilities that are on part of the Developer's property are being improved to better adapt
to the runoffs directed to them. Rating curves for those improved ponds have been
modified to account for the recontouring, while the offsite Pond 301 rating curve has not
been changed.
Registry Ridge P.U.D. Page 3
Final Drainage Report
402-406 and to Lang Gulch. There is an existing forty-eight (48) inch RCP under
Trilby Road at the outlet of proposed Detention Pond 601. This pipe will be extended
upon development of the site. The existing culvert under Shields Street at Lang Gulch
is a sixty-six (66) inch RCP and the existing pipe under Trilby Road at the outlet of
proposed off -site detention pond 303 is a seventy-two (72) inch RCP.
There are existing wetlands located on the site adjacent to Lang Gulch. A
separate report by Riverside Technology has been submitted with the Preliminary
submittal for Registry Ridge P.U.D. and have been delineated on the Preliminary
Drainage Plan.
IV. DEVELOPED DRAINAGE
4.1 Developed Conditions
Planned development within Registry Ridge P.U.D. includes:
• Low and Medium Density Single Family Residential Homes,
• Tracts set aside for Future Multi Family, Future Commercial,
Future Daycare, Future Recreation, Future School and Parks,
0 new local streets,
• and culvert crossings,
The downstream parcel of land, from the east side of Shield Street to the C&S
Railroad tracks, is owned by Colorado Land Source Ltd. which is also the developer of
Registry Ridge P.U.D..
4.2 Design Criteria and References
Drainage criteria outlined in both the City of Fort Collins Storm Drainage Design
Criteria Manual,(SDDCM) and Storm Drainage Criteria Manual by the Urban Drainage
and Flood Control District have been referenced for this Final Drainage Study.
4.3 Hydrologic Criteria
The Rational Method has been used to estimate peak stormwater runoff within
the developed site. The initial 2-year and major 100-year design storms have been
used in the evaluation of the proposed drainage system. Rainfall intensity data for the
Rational Method has been taken from IDF curves and equations generated specifically
for the Registry Ridge P.U.D. site by the computer program "Watershed Modeling" by
Eagle Point. Input of precipitation amounts have been taken from the NOAA Atlas 2,
Volume III- Colorado. Compared to Figure 3-1 in the SDDCM, rainfall intensities
generated for the Registry Ridge site were approximately 15% higher than intensities
given in Figure 3-1.
Off -site runoff has been estimated through the use of SWMM. The developed
Registry Ridge P.U.D. Page 2
Final Drainage Report
II. SITE LOCATION AND DESCRIPTION
2.1 Site Location
The site is located within the East Half of Section 15, Township 6 North, Range
69 West of the 6th Principal Meridian in Fort Collins, Colorado. The project is
bounded by Trilby Road on the north and Shields Street on the east. (See Vicinity
Map).
2.2 Site Description
Registry Ridge P.U.D. is approximately 244.459 acres and has historically been
furrowed agricultural land. Existing structures on the site include a metal pole barn
located in the northeast corner of the site.
2.3 Irrigation Ditches and Reservoirs
Lang Gulch traverses the south end of the site flowing from west to east. The
City of Fort Collins has delineated the 100-year floodplain for Lang Gulch which is
reflected on the Drainage and Grading Plans. There are no existing irrigation laterals
on the site.
III. HISTORIC DRAINAGE BASIN
3.1 Maoor Basin Description
The site is located in the Fossil Creek Drainage Basin and is included in the
report entitled Fossil Creek Drainage Basin Master Drainageway Planning Study, by
Simons, Li & Associates, Inc., August, 1982. The SWMM model developed as part of
the Master Study has been updated by Northern Engineering to reflect proposed
developed conditions.
3.2 Historic Drainage Patterns
The site historically drains from west to east at slopes ranging from 1.4 to 8.8%.
' The majority of the site is tributary to Lang Gulch (Developed Basins' 402- 406).
Basin 401 which is located in the northwest corner of the site adjacent to Trilby Road
drains to a tributary of Smith Creek. This tributary joins with Smith Creek
' approximately 2000' north of Trilby Road. The confluence of Smith Creek and Lang
Gulch is located approximately 2000 feet east of South Shields Street. Ponding
presently occurs along Lang Gulch west of South Shields, west of the C&S Railroad
' and south of Trilby Road. Ponding also occurs along the Smith Creek tributary south
of Trilby Road.
Off -site runoff enters the site along the west property line. Approximately 49.5
acres of this off -site runoff will be routed through proposed Detention Pond 601 and to
Smith Creek Tributary. Roughly 228.6 acres will be routed through developed Basins'
Final Drainage Report
for
Registry Ridge P.U.D.
I. INTRODUCTION
1.1 Objective
To provide a final drainage scheme for the proposed Registry Ridge
planned unit development based on master drainageway planning and overall/
preliminary drainage concepts. Specific objectives as part of this study are:
To adopt the drainage concepts contained in the Fossil Creek
Drainage Basin Master Drainagewy Planning Study, (Reference
1),
2. To consider the drainage schemes of all adjacent properties,
3. To perform SWMM modeling to reflect proposed developed
conditions,
4. To consider any possible adverse effects downstream of the
development due to developed stormwater,
1.2 Mapping and Surveying
A field survey of the site was conducted by Landstar Surveying, Inc.
Loveland, Colorado. Based on this field survey information, topographic mapping was
computer generated with a contour interval of one (1) foot.
1.3 Site Reconnaissance
A site visit was conducted on Monday June 10, 1996 by the project
engineer. Based on the topographic mapping, existing drainage basins and land use
' were confirmed as well as existing structures. The location and dimensions of existing
culverts and storm inlets were verified as well as their condition and flow direction.
VICINITY MAP
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June 24, 1996
City of Fort Collins
Stormwater Utility
235 Mathews
Fort Collins, Colorado 80522
RE: Registry Ridge P.U.D.
Fort Collins, Colorado
Project Number: 9615.00
Dear Staff:
Northern Engineering Services, Inc. is pleased to submit this Final Drainage
Report for Registry Ridge P.U.D. for your review.
This report was prepared in compliance with technical criteria set forth in the
City of Fort Collins Storm Drainage Design Criteria and Construction Standards
manual.
If you should have any questions or comments as you review this report, please
feel free to contact me at your convenience.
Sincerely,
NORTHERN ENGINF��B�AICES, INC.
'sue 30325
Mary B. Wohnrade,
0
420 SOUTH HOWES, SUITE 202, FORT COLLINS, COLORADO 80521, (970) 221-4158, FAX (970) 221-4159
Final Drainage Report
for
Registry Ridge P.U.D.
Fort Collins, Colorado
June 24, 1996
Prepared For:
Colorado Land Source Ltd.
8101 East Prentice Ave. Suite M180
Englewood, Colorado 80111
Prepared By:
Northern Engineering Services, Inc.
420 South Howes, Suite 202
Fort Collins, Colorado 80521
(970)221-4158
Fax (970)221-4159
Project Number: 9615.00
First Final Submittal
I
Final Drainage Report
for
Registry Ridge P.U.D.
Fort Collins, Colorado
June 24, 1996