HomeMy WebLinkAboutSOUTH SHIELDS VETERINARY CLINIC PUD - FINAL - 44-89B - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTFINAL DRAINAGE INVESTIGATION
FOR
LAURIE SUBDIVISION
FORT COLLINS, COLORADO
Prepared for
Dr. William Musslewhite
5001 S. Sheilds Street
Fort Collins, Colorado 80526
December 29, 1989
Commission No. 1180-01-01-02
CONSULTING ENGINEERS
FOUNDATION ENGINEERING
320 N. CLEVELAND AVENUE
LOVELAND, COLORADO 80537
December 29, 1989
Commission No. 1180-01-01-02
Dr. William Musslewhite
5001 S. Shields Street
Fort Collins, Colorado 80526
Dear Dr. Musslewhite,
The enclosed report represents the results of the final drainage investigation
for the LAURIE SUBDIVISION located in the Northeast Quarter of Section 3,
Township 6 North, Range 69 West of the 6th P.M. Larimer County, Colorado.
This investigation was based upon the proposed site development plan and plat;
proposed site development construction plans; on -site observations; and
available topographic information. The investigation was performed in
accordance with the criteria established in the City of Fort Collins -"Storm
Drainage Design Criteria and Construction Specification Standards" manual.
It is our opinion that the proposed construction is feasible provided that the
recommendations contained in the attached report and the incorporated final
design are performed in accordance with the final approved plans for the
project.
If you should have any questions, please call.
)rson, P.E.
ENGINEERING
KW P/drm
TABLE OF CONTENTS
Letter of Transmittal i
Table of Contents
Scope 1
Site Description 1
Existing Conditions 1
Proposed Development 2
Conclusions and Recommendations 2
EXHIBITS
Vicinity Map Exhibit A
Calculations Exhibit B
Drainage Plan Exhibit C
COPE
The following report represents the results of a drainage investigation for a
proposed development to be known as the LAURIE SUBDIVISION located on a
parcel of land situated in the Northeast Quarter of Section 3, Township 6 North,
Range 69 West of the 6th P.M., Larimer County, Colorado. The investigation was
performed for Dr. William Musslewhite. The purpose of this investigation is to
determine the effects of the proposed development on the areas existing
drainage conditions and to determine the improvements, if any, and the
appropriate sizing for proposed improvements so that it may be incorporated
with the construction of the project. The conclusions and recommendations
presented in this report are based upon the proposed site development plan and
plat; proposed site development construction plans; on -site observations; and
the available topographic information. The analysis was performed in
accordance with the City of Fort Collins- "Storm Drainage Design Criteria and
Construction Standards" manual.
SITE DESCRIPITION
The site is generally rectangular in shape and contains approximately eight
acres. The sites East-West dimension is approximately 1,150 feet and its
North -South dimension varies from approximately 390 feet at the westerly
boundary to approximately 280 feet at the easterly boundary. The site abuts the
westerly right-of-way of Shields Street at a point approximately one-half mile
south of Harmony Road. The site is located on the Burns Tributary of the FOSSIL
CREEK DRAINAGE BASIN.
EXISTING CONDITIONS
The site is presently used as a large residential tract with the existing
structures located at the southeast corner of the site near Shields Street. The
Pleasant Valley and Lake Canal passes through the adjacent property to the
north with a lateral of that ditch flowing through the site. Near the center of
the site is a ravine that has been created by scouring action associated with an
overflow discharge from the Canal as it flows across the site toward the South.
According to the irrigation company's officials the overflow to the ravine is
designed to discharge a maximum flow of 30 c.f.s. (cubic feet per second)
East of the lateral ditch passing through the site, the property slopes gently to
the East toward Shields Street at a slope of approximately 2%. The area below
the ditch is irrigated and is used for pasture except for the residence and
out -buildings at the southeast corner of the site.
1
s 0
The portion of the site that lies West of the ravine is not irrigated and slopes
rather steeply at approximately 15% toward the Burns Tributary of FOSSIL
CREEK. The area is sparsely vegitated with ground cover consisting mainly of
native grasses and sage brush. The site abuts THE RIDGE Subdivision at the West
and South.
The site receives run-off from the properties to the North and West. For the
purposes of this investigation, the area above the Pleasant Valley and Lake
Canal was not considered to effect the conditions onsite since the ditch flow is
controlled to the extent that there is an existing overflow structure that
directs excess flow to the ravine through the site, as previously stated. The
area to the North consists of approximately 10.5 acres which drains easterly to
Shields Street and then southerly along the west side of Shields Street through
the site. An area of approximately 2.5 acres drains into the smaller side ravine
that enters the site at the mid -point of the the northern boundary.
Approximately 4.5 acres drains directly into the major ravine before it enters
the site near the northwest corner.
PROPOSED DEVELOPMENT
The proposed construction is to consist of a vetinary clinic with associated
parking that is to be located near the northeast corner of the site adjacent to
Shields Street. A new cul de sac street is to be constructed to serve the new
clinic and the existing residence. The cul de sac is to be extended to a circular
turn -around west of the existing and proposed construction in order to provide
access to the area to the west. At this time the future development to the west
is being proposed to be residential in nature with nine (9) lots to be platted.
CONCLUSIONS AND RECOMMENDATIONS
1. The proposed development will retain the existing drainage patterns.
2. The site is located in the FOSSIL CREEK DRAINAGE BASIN. The site is not
located within the floodway or flood plain.
3. All development is to be performed in accordance with City of Fort Collins
Standards and Specifications.
4. Onsite detention of stormwater is not recommended due to the sites
proximity to the existing "Major" drainage course.
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7
Dr. Musslewhite-Laurie Subdivision Commission No. 1180-01-01-02
By: DRM Date: Dec. 29, 1989
Calculations for Drainage Investigation for LAURIE SUBDIVISION located in the
NE1/4 of Section 3, Township 6 North, Range 69 West of the 6th P.M., City of
Fort Collins, Larimer County, Colorado
Total Site Area = 8 acres +/-
EXISTING CONDITIONS
Rational "C" Factor = 0.20 for Offsite Irrigated Areas
If
of
if = 0.25 for Off site Steeper Non -irrigated Areas
tv itit= 0.25 for Onsite Irrigated Areas
it to
of
= 0.30 for Onsite Steeper Non -irrigated Areas
PROPOSED DEVELOPMENT
Rational "C" Factor = 0.225 for Lawns and Landscaped Areas
if of it = 0.95 for Roofs, Decks, Patios, etc.
if V1 of = 0.95 for Streets, Drives, and Parking
Lawns and Landscaped Areas = 29,413 sq.ft.
Roofs, Decks, Patios, etc. = 4,400 sq.ft.
Streets, Drives, and Parking = 13,800 sq.ft.
Area of Site Consideration = 325' x 146.5' = 47,613 sq.ft.
"Q" avg = {(29,413 x 0.225) + (4,400 x 0.95) + (13,800 x 0.95)) / 47,613
"Q"avg = 0.50
Refer to following calculations for runoff quantity determination.
CULVERT SIZING
1.)New culvert to be installed at cul de sac street from Shields Street. The
culvert is considered to be at "Inlet Control". Based upon the runoff calculations
the design flows at this point are: Q2 = 6 cfs and Qloo = 20 cfs ; therefore -
Using the Design Nomograph for Circular Pipe at Inlet Control:
@ HW/D = 1.0 and Q = 6 cfs an 18" dia. pipe will be sufficient
@ HW/D = 1.5 and Q = 20 cfs a 24" dia. pipe will be required
USE a 24" dia. pipe to meet both conditions
Dr. Musslewhite-Laurie Subdivision
By: DRM
CULVERT SIZING(cont.)
Commission No. 1180-01-01-02
Date : Dec. 29, 1989
2.) Culvert at future cul de sac street crossing on major ravine.
Design "Q"= 49.5 cfs (19.5 + 30). Since irrigation flow is incorporated consider
only HW/D = 1.0
From Design Nomograph: @ HW/D = 1.0 and "Q" = 49.5 cfs a 42" dia. pipe will
be sufficient. Since a 48" culvert exists immediately downstream and
considering for trash build-up at he culvert entrance, recommend a 48" dia.
pipe.
USE a 48" dia. pipe to provide for combined drainage and irrigation flows.
EROSION CONTROL
The primary area of concern is the ravine running thru the site. This may require
some type of "drop structures" along its course and inlet and outlet protection
at the proposed culvert under the cul de sac street. Additional protection at the
inlet and outlet ends of the culvert at Shields Street should also be provided.
The City's Standard Erosion treatments for wind and storm -runoff should also
be incorporated during the course of construction.
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