HomeMy WebLinkAboutPETERSON PLACE (611 S. PETERSON) - PDP - 35-00 - SUBMITTAL DOCUMENTS - ROUND 3 - DRAINAGE REPORTIr 1.4k&
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Figure 51:
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FLOODED AREA MAPPING
OLD TOWN
I MASTER DRAINAGE
BASIN PLAN for the
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APPENDIX A
Preliminary Drainage Study
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1. Temporary seeding on all of the land to be developed
2. Silt fences installed on the Northern side of the development
3. Vehicle tracking control
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ICONCLUSION
The runoff that will be produced by 611 Peterson Street has been accounted for. The
allowable release rate from the detention pond was set such that the total runoff to South
Peterson Street will not exceed the current 100 year peak runoff.
EROSION AND SEDIMENT CONTROL
This report describes methods which are recommended to control wind erosion, water
erosion and sediment during and after the construction of drainage structures and site
grading.
1 DISCUSSION
The clearing and stripping of land for site grading, overlot grading, or for the construction
of drainage structures, may cause localized erosion rates with subsequent deposition and
damage to offsite properties. Uncontrolled, such erosion could destroy the aesthetic and
practical values of individual sites, and cause damage to downstream property.
In general, erosion and sediment control measures will consist of minimizing soil
exposure, controlling runoff across exposed areas, and sediment control at drainage
structures. Each of these measures is described below and should be utilized by the
developer and/or the contractor during any construction activity that occurs at this site.
GENERAL EROSION AND SEDIMENT CONTROL MEASURES
Minimizing Soil Exposure: Where practical, the construction area and duration of soil
exposure should be kept to a minimum. All other areas should have a good cover of
vegetation or mulch. Grading should be completed as soon as possible after
'I commencement. A temporary cover crop, a permanent vegetative cover crop, or other
landscaping should be established in the disturbed areas. Re -vegetation may consist of
native grasses, lawn grasses, or various winter wheat. Decorative rock, flower gardens, or
t shrubs may also be utilized in the final landscaping to cover the soil. Re -seeded areas
should be mulched with straw or hay to protect exposed soil until vegetation is
■ established.
IEROSION CONTROL PLAN
The proposed erosion control measures are presented on the Grading and Erosion Control
Plan located in the Appendix of this report.
In summary, the erosion control measures consist of:
I
least 1.5 feet above the revised 100 year flood elevation. Please refer to the flood plain
report for the site.
Offsite Basins
Due to the construction of the adjacent streets, the only offsite drainage basin that enter
this site are from the existing apartment building and parking lot located immediately
south of this project.
Onsite Basins
Sub -basin A- This sub -basin consists of the western 0.08 acre basin that drains to a
proposed curb -cut in the proposed parking lot. Sub -basin A is the onsite
area that drains to the proposed detention pond. The basin proposed land
use consists of %z of the proposed building with the remainder being either
parking lot or landscaped.
Sub -basin B- This sub -basin consists of the eastern 0.20 acre basin that drains undetained
to South Peterson Street. The basin proposed land use consists of %z of the
proposed building and all of the existing building with the remainder being
either asphalt driveway or landscaped.
Sub -basin OS1- This offsite sub -basin consists of the southern 0.02 acre basin that drains
from the existing parking lot to the proposed detention pond. The basin
proposed land use consists of asphalt paving.
OFFSITE RUNOFF
A small amount of runoff enters this site from the south and drains onto the site at the
southwest corner (Sub -basin OS1).
ONSITE RUNOFF
The runoff produced from Sub -basin A and the existing offsite Sub -Basin OS I, drains
into the proposed Detention Pond.
Detention Pond - The release rates for the detention pond has been set to equal the current
100 year peak runoff rate from Sub -basins A, B, and OS 1 (0.86 cfs) less the amount of
un-detained runoff from Sub -basin B (0.55 cfs) for a total release rate of 0.31 cfs. The
discharge from the detention pond will drain in a proposed concrete pan and through a
proposed sidewalk culvert to South Peterson Street.
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PRELIMINARY DRAINAGE STUDY
FOR 611 SOUTH PETERSON STREET
Introduction
611 South Peterson Street is a proposed multi -family residential subdivision in the City
of Fort Collins, Colorado. The site is generally located on the West side of South
Peterson Street midway between East Myrtle Street and East Laural Street. The entire site
is located within the Northwest'/4 of Section 13, T7N, R69W, Sixth Principal Meridian,
Larimer County, Colorado. The Site consists of approximately 0.28 acres.
The purpose of this drainage study is to evaluate and present the drainage impacts from
611 South Peterson Street on the adjacent downstream properties. In the evaluation, a site
description of the project and its relationship to the Master Drainage Basin will be
presented. The drainage report will present the changes to the developed flow conditions
and proposed improvements to resolve the impact of the drainage flow condition.
Existing Condition Description
Currently the ground is nearly flat and covered with a grass lawn as well as an existing
house and out buildings. The site is bound by South Peterson Street on the East, existing
apartment building and parking lot on the South, existing single family homes on the
North and an alley on the West.
In the present state, a majority of the site drains from the West to the East at slopes from
0% to 0.4%. The current runoff drains across the existing sidewalk and onto South
Peterson Street.
A small portion of the existing parking lot for the apartment development to the south
drains onto this site.
Drainage Impact
Proposed Site Conditions
611 South Peterson Street consists of 1 new building with 3 dwelling units. In addition to
the 1 additional residential building, there are 6 proposed parking spaces. The proposed
development is accessed by an alley adjacent to the western boundary.
Major Drainage Basins
' 611 South Peterson Street lies within the Old Town Master Drainage Basin. More
particularly, it is within Reach 3 of the Old Town Basin. The Old Town Master Drainage
Basin has delineated the 100 year flood plain for this area. The site is entirely within the
City's designated 100 year flood plain. The proposed finish floor elevation will be at
Table of Contents
I
Introduction................................................................................page 1
ExistingCondition.........................................................................page 1
DrainageImpact...........................................................................page 1
Proposed Site Conditions
Major Drainage Basins
Offsite Basins
Onsite Basins
1 Offsite Runoff.............................................................................page 2
OnsiteRunoff.............................................................................:page 2
1
Conclusion.................................................................................page 3
Erosion and Sediment Control.......................................................... page 3
APPENDIX A
Preliminary Drainage Study
A 0. 96; 270852
57w eo& a, ed 80527
(970) 493-2909
57,4X (970)495- l735
' September 12, 2000
Project No. 0029
I
Mr. Donnie Dustin
City of Fort Collins
Stormwater Utility Department
700 Wood Street
Fort Collins, CO 80522
Dear Mr. Dustin:
On behalf of our client we are submitting the attached Preliminary Drainage
Study for 611 South Peterson Street. The purpose of this report is to evaluate and present
the drainage impacts from the proposed Construction of 611 South Peterson Street. The
drainage report will present the changes to the developed flow conditions and proposed
improvements to resolve the impacts of the drainage flow condition.
The Preliminary Drainage Study for 611 South Peterson Street was prepared in
accordance with the provisions of the City of Fort Collins Storm Drainage Criteria —
revised January 1997.
Loonan and Associates, Inc.
James R. Loonan, P.E.
Registered Professional Engineer
Colorado P.E. 19195
PRELIMINARY DRAINAGE STUDY
AND 'EROSION:=CONTROL REPORT
FOR 611 SOUTH PETERSON
..
Prepared For
Mr Bruce Froseth
524 Spring Canyon Court
Fort Collins, Q0, 80525
Date: September 12,:•2000
Project No, 0029
Con"sulking Engineer
Loonan and Associates, Inc.
:-
. 1631 South College Ave..
_
P .O:.Box 270852
Fort Collins, CO :80527
U
In general, erosion and sediment control measures will consist of minimizing soil
exposure, controlling runoff across exposed areas, and sediment control at drainage
structures. Each of these measures is described below and should be utilized by the
developer and/or the contractor during any construction activity that occurs at this site.
GENERAL EROSION AND SEDIMENT CONTROL MEASURES
Minimizing Soil Exposure: Where practical, the construction area and duration of soil
exposure should be kept to a minimum. All other areas should have a good cover of
vegetation or mulch. Grading should be completed as soon as possible after
commencement. A temporary cover crop, a permanent vegetative cover crop, or other
landscaping should be established in the disturbed areas. Re -vegetation may consist of
native grasses, lawn grasses, or various winter wheat. Decorative rock, flower gardens, or
shrubs may also be utilized in the final landscaping to cover the soil. Re -seeded areas
should be mulched with straw or hay to protect exposed soil until vegetation is
established.
EROSION CONTROL PLAN
The proposed erosion control measures are presented on the Grading and Erosion Control
Plan located in the Appendix of this report.
In summary, the erosion control measures consist of:
1. Temporary seeding on all of the land to be developed
2. Silt fences installed on the Northern side of the development
3. Vehicle tracking control
i
I
Detention Pond - The release rates for the detention pond has been set to equal the current
100 year peak runoff rate from Sub -basins A, B, C, and D (0.75 cfs) less the amount of
un-detained runoff from Sub -basin B, C, and D (0.72 cfs) for a total release rate of 0.03
cfs. The required volume of detention for a 0.03 cfs release rate is 410 cubic feet.
However, only 385 cubic feet of detention volume can be provided. For 385 cubic feet of
storage, the release rate is 0.04 cfs. Therefore, there will be a net increase in runoff from
this site on 0.01 cfs during the 100 year storm. The discharge from the detention pond
will drain into a proposed concrete pan/curb and gutter, and through a proposed culvert to
South Peterson Street. We are requesting a variance from the City of Fort Collins
stormwater policy to allow an increase 100 year runoff of 0.01 cfs from this site as well
as the one foot freeboard for the detention pond. Due to the flatness of the site, it is not
feasible to provide 1.0 foot freeboard.
Stormwater Quality — Due to the flatness of the site and other restraints such as the size
of the project, the existing building location, and the limited grade difference to the
outfall point (flowline of Peterson Street), we propose using a grass lined Swale to
provide filtration of the stormwater. The swale will be located between the proposed
parking lot and the east -west conveyance gutter. The grass swale will be at a one percent
slope and will have a distance of 16 feet. The reason that a 1 percent slope was chosen
over the City's 2 percent policy was because of the potential impact to the flood plain.
Using a 2 percent slope would raise the parking lot 0.16 feet. Therefore, we are
requesting a variance to the City's 2 percent minimum grade for grass lined channels.
The flatter slope will provide better stormwater quality treatment.
CONCLUSION
The runoff that will be produced by 611 Peterson Street has been accounted for. The
allowable release rate from the detention pond was set such that the total runoff to South
Peterson Street will exceed the current 100 year peak runoff by only 0.01 cfs.
EROSION AND SEDIMENT CONTROL
This report describes methods that are recommended to control wind erosion, water
erosion and sediment during and after the construction of drainage structures and site
grading.
DISCUSSION
The clearing and stripping of land for site grading, overlot grading, or for the construction
of drainage structures, may cause localized erosion rates with subsequent deposition and
damage to offsite properties. Uncontrolled, such erosion could destroy the aesthetic and
practical values of individual sites, and cause damage to downstream property.
I
least 1.5 feet above the revised 100 year flood elevation. Please refer to the flood plain
report for the site.
rOffsite Basins
Due to the construction of the adjacent streets, the only offsite drainage basin that enters
this site is from the existing apartment building and parking lot located immediately
south of this project.
Onsite Basins
Sub -basin A- This sub -basin consists of the western 0.05 acre basin that drains to a
proposed curb -cut in the proposed parking lot. Sub -basin A is the onsite
area that drains to the proposed detention pond. The basin proposed land
use consists of a small portion of the roof from the proposed building with
the remainder being either parking lot or landscaped.
Sub -basin B- This sub -basin consists of the eastern 0.17 acre basin that drains undetained
to South Peterson Street. The basin proposed land use consists of the
proposed building and '/2 of the existing building with the remainder being
either concrete walks or landscaping.
Sub -basin C- This sub -basin consists of the northeastern 0.05 acre basin that drains un-
detained to South Peterson Street. The basin proposed land use consists of
%2 of the existing building with the remainder of the area being landscaping.
Sub -basin D- This sub -basin consists of the western 0.004 acre basin that drains un-
detained to the existing Alley. The basin proposed land use consists of
concrete driveway and landscaping.
Sub -basin OS1- This offsite sub -basin consists of the southern 0.18 acre basin that drains
from the existing parking lot and the rooftop of the existing apartment
building to the proposed conveyance channel. The basin proposed land use
consists of asphalt paving, roof tops, and landscaping.
OFFSITE RUNOFF
A small amount of runoff enters this site from the south and drains onto the site along the
southern property line (Sub -basin OS1).
ONSITE RUNOFF
The runoff produced from Sub -basin A drains into the proposed Detention Pond.
2
FINAL DRAINAGE STUDY
FOR 611 SOUTH PETERSON STREET
IIntroduction
611 South Peterson Street is a proposed multi -family residential subdivision in the City
of Fort Collins, Colorado. The site is generally located on the West side of South
Peterson Street midway between East Myrtle Street and East Laural Street. The entire site
is located within the Northwest ''/< of Section 13, T7N, R69W, Sixth Principal Meridian,
Larimer County, Colorado. The Site consists of approximately 0.28 acres.
The purpose of this drainage study is to evaluate and present the drainage impacts from
611 South Peterson Street on the adjacent downstream properties. In the evaluation, a site
description of the project and its relationship to the Master Drainage Basin will be
presented. The drainage report will present the changes to the developed flow conditions
and proposed improvements to resolve the impact of the drainage flow condition.
Existing Condition Description
Currently the ground is nearly flat and covered with a grass lawn as well as an existing
house and out buildings. The site is bound by South Peterson Street on the East, existing
apartment building and parking lot on the South, existing single family homes on the
North and an alley on the West.
In the present state, a majority of the site drains from the West to the East at slopes from
0% to 0.4%. The current runoff drains across the existing sidewalk and onto South
Peterson Street.
A small portion of the existing parking lot as well as a portion of the building for the
apartment development to the south drains onto this site.
Drainage Impact
Proposed Site Conditions
611 South Peterson Street consists of 1 new building with 3 dwelling units. In addition to
the 1 additional residential building, there are 4 proposed parking spaces. The proposed
development is accessed by an alley adjacent to the western boundary.
Major Drainage Basins
611 South Peterson Street lies within the Old Town Master Drainage Basin. More
particularly, it is within Reach 3 of the Old Town Basin. The Old Town Master Drainage
Basin has delineated the 100 year flood plain for this area. The site is entirely within the
City's designated 100 year flood plain. The proposed finish floor elevation will be at
Table of Contents
Introduction................................................................................page 1
ExistingCondition.........................................................................page 1
DrainageImpact...........................................................................page 1
Proposed Site Conditions
Major Drainage Basins
Offsite Basins
Onsite Basins
OffsiteRunoff.............................................................................page 2
OnsiteRunoff..............................................................................page 2
Conclusion.................................................................................page 3
Erosion and Sediment Control.......................................................... page 3
APPENDIX A
Erosion and Sediment Control Calculations
APPENDIX B
Final Drainage Study Calculations
P. 0, Tax 270852
57ne Via, eO 90527
�! (970) 493-2808
5742 (970) 495- 9735
June 28, 2001
Project No. 0029
Mr. Donnie Dustin
City of Fort Collins
Stormwater Utility Department
700 Wood Street
Fort Collins, CO 80522
Dear Mr. Dustin:
On behalf of our client we are submitting the attached Final Drainage Study for
611 South Peterson Street. The purpose of this report is to evaluate and present the
drainage impacts from the proposed construction of 611 South Peterson Street. The
drainage report will present the changes to the developed flow conditions and proposed
improvements to resolve the impacts of the drainage flow condition.
The Final Drainage Study for 611 South Peterson Street was prepared in
accordance with the provisions of the City of Fort Collins Storm Drainage Criteria —
revised January 1997.
Loonan and Associates, Inc.
es R. Loon41�.
Registered Professional Engineer
Colorado P.E. 19195
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