HomeMy WebLinkAboutSHOPKO P.U.D., PAD B - PDP - 28-03 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTPROJECT SITE
VICINITY MAP
APPROXIMATE SCALE: 1' - 1000'
SHEET 1 OF 1
DATE: 07/15/03 PARCEL •B• %North Star
SCALE: 1" = 1000' design, inc.
AT SHOPKO P.U.D. 700Automation aneso IDRAWN BY: TDS os
VICINITY MAP Phone: 970-686-6939
JOB NO.: 170-03 Fax: 970-686-1188
VICINITY MAP
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7. REFERENCES
1. City of Fort Collins, "Storm Drainage Criteria Manual", (SDCM), dated March, 1986.
2. The Final Drainage and Erosion Control Report for ShopKo P. U.D. by TST, Inc
dated May 11, 1993.
3. Urban Drainage and Flood Control District, "Urban Storm Drainage Criteria
Manual", Volumes 1 and 2, dated June 2001, and Volume 3 dated September, 1999.
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onto the paved surface. A stabilized construction entrance is required per the detail
shown on the Detail Sheet with base material consisting of 6" coarse aggregate. The
contractor will be responsible for clearing tracked mud on a daily basis.
5.5 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. Silt
fences will require periodic replacement. Maintenance is the responsibility of the
contractor.
6. CONCLUSIONS
6.1 Compliance with Standards
All computations that have been completed within this report are in compliance with the
City of Fort Collins Storm Drainage Design Criteria Manual.
6.2 Drainage Concept
The proposed drainage concepts presented in this report and on the construction plans
adequately provide for the detention and transmission of developed onsite runoff to the
existing storm system. The impact of the development of this site on existing
downstream facilities is has been minimized. Detention is being provided to meet
requirements set by the City of Fort Collins in accordance to the most recent rainfall
criteria standards.
If, at the time of construction, groundwater is encountered, a Colorado Department of
Health Construction Dewatering Permit would be required.
6.3 Erosion Control Concept
Since the site is less than 5.0 acres, a NPDES permit is not required. During
construction, erosion control shall be maintained to minimize erosion on this site and
transport of silt downstream.
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4.4 Variance Requests
No variances are being requested at this time.
EROSION CONTROL
5.1 General Concept
This site lies within the Moderate Rainfall and Wind Erodibility Zone per the City of Fort
Collins Zone Maps. A potential exists for silt movement from the site to be transported
into the onsite detention pond located in the southeast portion of the site. All erosion
control measures necessary to minimize sediment transport have been shown on the
Erosion Control Plan.
5.2 Specific Details
To limit the amount of silt leaving the site, several erosion control measures shall be
implemented during construction. Silt fence shall be installed along the southern, eastern
and western sides of the proposed site. Vehicle -tracking pads shall be installed at the
entrances to the existing asphalt area to control mud being tracked onto existing
pavement. During overlot grading, disturbed areas are to be kept in a roughened
condition and watered to reduce wind erosion.
5.3 Dust Abatement
During the performance of the work required by these plans, the contractor shall carry out
proper efficient measures wherever and as necessary to prevent dust nuisance, which 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 plans, on right-of-
way or elsewhere.
5.4 Tracking Mud
Wherever construction vehicles access routes intersect paved public roads, provisions
shall be made to minimize the transport of sediment (mud) by runoff or vehicles tracking
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curb & gutter and flow south in a swale near the east property line. Runoff will enter
' Storm 1 and will be conveyed to the East Pond. Runoff from this basin is undetained and
therefore flow is deducted from the allowable release rate for the detention pond.
Sub -basin 3 contains the east central portion of the site including half of the east building
and landscaped area. Runoff from this basin flows to the south in a Swale to the detention
pond.
Sub -basin 4 contains the southeast portion of the site including the remainder of the east
building and the water quality / detention area. Runoff from this basin sheet flows into
the detention pond. In the event that the detention pond should overtop, runoff will be
conveyed to Boardwalk Drive over the spillway located on the south side of the detention
pond. This overflow will flow west in curb & gutter to College Avenue and eventually
into Fossil Creek.
Sub -basin 5 contains the southwest building. Runoff from this basin will be collected in
roof drains and discharged directly to Storm 3. Storm 3 connects to Storm 2 and conveys
runoff to the detention pond.
Sub -basin 6 contains the south portion of the site and consists entirely of landscaped
area. Runoff from this basin will be conveyed south to Boardwalk Drive, west to College
Avenue and eventually to Fossil Creek. Runoff from this basin is undetained and
therefore flow is deducted from the allowable release rate for the detention pond.
Runoff from Basins 1, 3, 4 & 5 enter the onsite detention area. After being detained, the
water will enter Storm 1 and will be conveyed to the East Pond. Release from the East
Pond is conveyed to the No. 2 Canal.
4.3 Drainage Summary
The storm conveyance system is a surface and sub -surface system and has been designed
for minimal maintenance. The proposed storm sewer system and the detention pond will
be owned and maintained by the property owner(s).
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3.4 Hydraulic Criteria
All hydraulic calculations within this report have been prepared in accordance with the
City of Fort Collins Drainage Criteria and are also included in Appendix B of this report.
4. DRAINAGE FACILITY DESIGN
4.1 General Concept
Runoff from this site will flow south in the parking lot via sheet flow and curb & gutter to
the proposed storm system. This system will convey runoff to the detention pond. The
existing storm sewer system has been modeled using Haestad Methods StormCad v4.1.1.
Basin 2 is not routed through the detention pond. The amount of runoff from basin 2 was
deducted from the allowable release rate for the design of the detention pond. Runoff
generated by basin 2 is detained in the East Pond as described in Final Drainage Report
for ShcpKo P. U.D. Due to site constraints and the desire to save existing landscaping
Basin 6 will also be allowed to release undetained.
4.2 Specific Flow Routing
A summary of the drainage patterns within each basin is provided in the following
paragraphs. For more specific details see Drainage and Erosion Control Plan located in
the back packet and Appendix B for calculations.
Sub -basin 1 contains the central portion of the site including all of the onsite parking lot
and a portion of the parking lot north of the site. Runoff from this basin flows to the
south central portion of this basin to an inlet located at a low point. In the event that this
inlet should fail, runoff will overtop at the west entry area and will flow south to
Boardwalk Drive. This overflow will eventually reach Fossil Creek. Runoff is conveyed
to the detention pond through Storm 2. Buildings have been placed at an elevation that
will provide protection in the event of flooding.
Sub -basin 2 contains the northeast portion of the site including a small area of parking
north of the site. Runoff from this basin flows to the southeast corner of this basin to an
inlet located at a low point. In the event that this inlet should fail, runoff will overtop the
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The streets and associated drainage systems surrounding the site are existing. There is a
storm system existing in the east portion of the site. Runoff from this site has been
accounted for in the design of the existing storm sewer system designed with ShopKo
P.U.D. However with the rainfall criteria adopted in March 1998 detention and water
quality will need to be provided due to City of Fort Collins requirements.
Onsite detention is proposed for this site to account for this new rainfall criteria for the
City of Fort Collins Area. Release for this site will not exceed the approved 21.44 cfs
(100yr release rate for the old rainfall data). Runoff flows will enter the existing storm
sewer system and will be detained in the East Detention Pond as described in Final
Drainage Report for ShopKo P. U.D.
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It has been found that the existing storm sewer will not convey the allowable release rate
to the existing pond with the proposed storm sewer layout. Therefore it is proposed to
reduce the release rate from the detention outlet structure to a point where the 100yr HGL
' is slightly below the flowline elevation in the existing inlet located in JFK Parkway.
Allowable release from this site is 21.44 cfs. minus undetained flows, (basins 2 & 6)
which equals 18.0 cfs. This minimum release rate causes surcharging on the existing inlet
located on JFK Parkway, therefore to avoid flooding a proposed release rate from the
detention pond is limited to 17.25 cfs.
Water quality is also provided in the form of extended detention. Water quality
calculations are included in Appendix C.
3.3 Hydrologic Criteria
Runoff computations were prepared for the 10-year minor and 100-year major storm
frequency utilizing the rational method.
All hydrologic calculations associated with the basins are included in Appendix B of this
report. Standard Form 8 (SF-8) provides time of concentration calculations for all sub -
basins. Standard Form 9 (SF-9) provides a summary of the design flows for all Sub -
basins and Design Points associated with this site.
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area contributing to the water quality pond is approximately 2.33 acres. The additional
area (0.60 acres) being treated for water quality is from the south wall of ShopKo Retail
store to the north property line of this site. There is an existing detention pond located in
the northeast comer of ShopKo P.U.D. that is labeled as East Pond in Final Drainage
Report for ShopKo P. U.D. Runoff from this proposed development will be conveyed to
the existing storm system and to the East Pond. Runoff from the East Pond is discharged
into the No. 2 Canal northeast of the site. In the event that the required water quality /
detention pond should overtop runoff will be conveyed to Fossil Creek in the Fossil
Creek Drainage Basin.
Due to existing landscaping that is required to be saved, the southern portion of the site is
unable to be graded so runoff is conveyed to the proposed detention pond. It is proposed
to allow this undetained flow to enter Boardwalk Drive and flow west on Boardwalk
Drive to College Avenue. This undetained runoff flows from landscape areas and
therefore runoff have maintained good water quality. Runoff from this undetained basin
will be conveyed to Fossil Creek. This undetained runoff is deducted from the allowable
release rate.
' 2.2 Sub -basin Description
Sub -basins are described thoroughly in Section 4.2.
3. DRAINAGE DESIGN CRITERIA
3.1 Regulations
This report was prepared to meet or exceed the "City of Fort Collins Storm Drainage
Design Criteria Manual' specifications. Where applicable, the criteria established in the
"Urban Storm Drainage Criteria Manual" (UDFCD), June 2001, developed by the Denver
Regional Council of Governments, has been used.
3.2 Development Criteria Reference and Constraints
Runoff from this site and the allowable release rate has been routed to conform to
existing drainage reports completed that have included this area, including the Final
Drainage Report for ShopKo P. U.D., Dated May 11, 1993 by TST Inc. Project Number
10-724-000.
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1. GENERAL LOCATION AND DESCRIPTION
1.1 Location
This site is located in Tract °B" in the ShopKo P.U.D. Situated in the Northwest Quarter
of Section 36, Township 7 North, Range 69 West of the Sixth Principal Meridian, in the
City of Fort Collins, County of Larimer, State of Colorado. See the vicinity map in
Appendix A.
The project is located north of Boardwalk Drive and west of JFK Parkway. The site is
bounded to the north by existing commercial development (ShopKo retail store), to the
east and south by existing JFK Parkway and Boardwalk Drive and an existing parking
access road to the west.
1.2 Description of Property
The entire project consists of approximately 1.76 acres of undeveloped land. This site
has existing curb and gutter along the eastern, western and southernboundaries. A 4.0'
high stockpile of dirt exists in the center of this site. Existing onsite flows are routed to
an existing inlet located in a sump the southeast comer. The site slopes from the north to
the southeast at slopes ranging from 0.5% to 4.0%. The proposed development consists
of two buildings that will be used as office space, retail and possible auto related uses.
The site will gain access from existing drives on JFK Parkway and Boardwalk Drive and
from -the existing ShopKo Parking lot.
1 2. DRAINAGE BASINS AND SUB -BASINS
2.1 Major Basin Description
The proposed development lies within the McClellands Mail Creek Drainage Basin and
Fossil Creek Drainage Basin. The site is included in the area covered by the Final
Drainage Report for ShopKo P. U.D. Portions of this report are included in Appendix E.
According to the above mentioned report, allowable release from this site is equal to
(21.44 cfs) the 100yr storm event for the old rainfall criteria. However since new rainfall
criteria ODF curves) have been adopted, it is required to detain for the difference between
the two rainfalls. Water quality is also required with the development of this site. The
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ITABLE OF CONTENTS
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TABLE OF CONTENTS.............................................................................................................................in
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1. GENERAL LOCATION AND DESCRIPTION
1.1 Location...............................................................................................................................I
1.2 Description of Property ........................................................................................................1
2. DRAINAGE BASINS AND SUB -BASINS
2.1 Major Basin Description......................................................................................................
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2.2 Sub -Basin Description.........................................................................................................2
3. DRAINAGE DESIGN CRITERIA
3.1 Regulations..........................................................................................................................2
3.2 Development Criteria Reference and Constraints................................................................2
3.3 Hydrologic Criteria..............................................................................................................3
3.4 Hydraulic Criteria................................................................................................................4
4. DRAINAGE FACILITY DESIGN
4.1 General Concept..................................................................................................................4
4.2 Specific Flow Routing.........................................................................................................4
4.3 Drainage Summary ..............................................................................................................5
4.4 Variance Requests...............................................................................................................6
5. EROSION CONTROL
5.1 General Concept..................................................................................................................6
5.2 Specific Details....................................................................................................................6
5.3 Dust Abatement...................................................................................................................6
5.4 Tracking Mud......................................................................................................................6
5.5 Maintenance........................................................................................................................7
6. CONCLUSIONS
6.1 Compliance with Standards................................................................................................7
6.2 Drainage Concept................................................................................................................7
6.3 Water Quality and Erosion Control Concept
.......................................................................7
7. REFERENCES.................................................................................................................................8
APPENDICES
A Vicinity Map
B Hydrologic & Hydraulic Calculations
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C Detention and Water Quality Calculations
D Erosion Control Calculations
E Figures and Tables
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F Excerpts from Previous Reports
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11 North Star
F1A.. design, inc.
July 25, 2003
Basil Hamdan
City of Fort Collins Stormwater
700 Wood Street
Fort Collins, CO 80522-0580
RE: Final Drainage Report for Parcel B at ShopKo P.U.D.
Dear Basil,
I am pleased to submit for your review and approval, this Final Drainage & Erosion Control
Report for Parcel B in ShopKo P.U.D. I certify that this report for the drainage design of Parcel
B in ShopKo P.U.D. was prepared in accordance with the criteria in the City of Fort Collins
Storm Drainage Manual.
I appreciate your time and consideration in reviewing this submittal. Please call if you have any
questions.
/Smcer
Tro praker, E.I.T.
Reviewed by:
Patricia Kroetch, P.E.
President
u
700 Automation Drive, Unit I Windsor, Colorado 80550
It 970-686-6939 Phone 970-686-1 1 88 Fax
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FINAL DRAINAGE AND
EROSION CONTROL REPORT
PARCEL B
SHOPKO P.U.D.
Prepared for:
Doberstein Lemburg
Dan Bernth
702 W. Drake Rd, Building E, Suite B-102
Fort Collins, CO 80525
Prepared by:
North Star Design, Inc.
700 Automation Drive, Unit I
Windsor, Colorado 80550
Ph# (970) 686-6939
Fax# (970) 686-1188
July 25, 2003
Job Number 170-03