HomeMy WebLinkAboutBLD2004-00705 Stormwater Managment Plan STORMWATER SITE PLAN
Block 21; Irving Park Addition
Jefferson County, WA
aQvt�
to wAToRPiAti
$.FORA![
* $
COUNTY vs•
ifootSON oi. 'EIOP l
.
s ►
SIGstac
Prepared for: Mr. Arnold Wood
2155 Discovery Road
Port Townsend,WA 98368
Prepared by: Colette M. Kostelec,P.E.
P.O. Box 2085
APPROVED Port Townsend, WA 98368 <AA.`
STORMWATER PLAN ARrE
��o WAS 11?►
LDEC 2 1 2004 May 4,2001 c,''�,r��` 1lt o �
t60-1a0N-i 5— 0 so --z
JEFFERSON COUNTY ••
QiA`S 33515
DEPT.OF CON. N TY Et. P IENT •• 4sct mtsc
SIGNATURE:
SIONALG
IEXPIRES \Z 101 I
4
STORMWATER SITE PLAN
Block 21; Irving Park Addition
TABLE OF CONTENTS
I. PROJECT OVERVIEW ..........»....»».».».»..........»......1
II. PLOT PLAN ""...».»....""'.."1
HI. PRELIMINARY CONDITIONS SUMMARY ••-...•••....»»....•-•.»...»..».......~•.»1
IV. OFF-SITE ANALYSIS »• """~-••"" """'"""'"""""""'2
V. STORMWATER RUNOFF CONTROL FACILITIES ." »-•»•»•»•"--»••»»•••••••2
A. Minimum Requirement#2:Preservation of Natural Drainage Systems 2
B. Minimum Requirement#3:Source Control of Pollution. 2
C. Minimum Requirement#4:Runoff Treatment BMPs 3
D. Minimum Requirement#5:Streambank Erosion Control 3
E. Minimum Requirement#6:Wetlands 4
F. Minimum Requirement#7:Water Quality Sensitive Areas 4
G. Minimum Requirement#8:Off-Site Analysis and Mitigation 5
H. Minimum Requirement#9:Basin Planning 5
I. Minimum Requirement#10:Operation and Maintenance 5
J. Minimum Requirement#11:Financial Liability 5
VI. SPECIAL REPORTS AND STUDIES •--•»••••............»."....'"».»..»....."'"6
VII. BASIN AND COMMUNITY PLANNING AREAS »-•»»•••-••»••»»••••••"- 6
VIII. OTHER PERMITS...»...».»......»....».».......".......».....»..............................»...».......»......"..»".......»....»....»
IX. LARGE PARCEL EROSION AND SEDIMENT CONTROL PLAN..».».».......»»»»..» -•»•»•-»»6
A. ESC Requirement#1:Stabilization and Sediment Trapping 7
B. ESC Requirement#2:Delineate Clearing and Facment Limits 7
C. ESC Requirement#3:Protection of Adjacent Properties 7
D. ESC Requirement#4:Timing and Stabilization of Sediment Trapping Measures 88
E. ESC Requirement#5:Cut and Fill Slopes 8
F. ESC Requirement#6:Controlling Off-Site Erosion
G. ESC Requirement#7:Stabilization of Temporary Conveyance Channels and Outlets 88
H. ESC Requirement#8:Storm Drain Inlet Protection 9
I. ESC Requirement#9:Underground Utility Construction 9
J. ESC Requirement#10:Construction Access Routes ." 10
K. ESC Requirement#11:Removal of Temporary BMPs 10
L. ESC Requirement#12:Dewatering Construction Sites
M. ESC Requirement#13:Control of Pollutants Other Than Sediment on Construction Sites 10
N. ESC Requirement#14:Maintenance 11
11
O. ESC Requirement#15:Financial Liability
X. MAINTENANCE AND OPERATIONS .........»»..»....»»...».......".......»»»...11
APPENDIX A RESULTS OF COMPUTER SIMULATIONS OF STORM EVENTS AND SIZING OF
STORMWATER FACILITIES
Stormwater Site Plan i May 4,2001
Block 21;Irving Park Addition
STORMWATER SITE PLAN
Block 21; Irving Park Addition
I. PROJECT OVERVIEW
This Stormwater Site Plan has been prepared for Block 21 and it's adjacent vacated rights-of-
way in the Irving Park Addition in unincorporated Jefferson County,Washington (Parcel
Number 963302106). The site is generally located between the intersections of Discovery
Road, State Highway 20 and Florence Avenue.A vicinity map for the site is provided on
Figure 1.
The site is approximately 2.85 acres and is divided into 8 building lots. Sheet CO1 shows the
site boundaries and existing site topography.Following clearing of the site, a Notice of
Voluntary Correction was issued by Jefferson County. The Correction Order requires
submittal of a Large Parcel Erosion and Sediment Control Plan.
This is a comprehensive report that provides information and analysis for the successful
implementation of stormwater controls during and after construction at the site in fulfillment
of the requirements of the Department of Ecology's Stormwater Management Manual for the
Puget Sound Basin(the"Technical Manual")dated February 1992.
The proposed development of the site will include installation of a water service line with
eight service connection stub-outs from the Jefferson County Public Utility District's eight-
inch water main that currently exists along the site's southern property boundary. Also
proposed is a 16-foot wide access road terminating in a cul-de-sac with a radius of 40 feet.
Existing site grades will be modified to allow for drainage from the access road and creation
of an infiltration pond. Proposed grades are shown on Sheet CO3.
II. PLOT PLAN
The following Sheets are included as part of this Stormwater Site Plan:
Sheet CO1 —Existing Site Plan
Sheet CO2—Erosion&Sediment Control Plan
Sheet CO3 —Permanent Stormwater Control Plan
Sheet C04—Construction Details
III. PRELIMINARY CONDITIONS SUMMARY
The project site is approximately 2.85 acres and slopes down approximately 12 feet from the
northern property boundary to the southwest corner at a 3%grade. A gentle ridge-line runs
north-south in the center of the property. Sheet CO1 shows existing topographic contours.
Surrounding land uses are single-family residential.
Stormwater Site Plan 1 May 4,2001
Block 21;Irving Park Addition
S
h
4 ,
PROJECT SITE
1
` � TRACE i 18 11 �Op� /it 11-j
SrV w uzx ,a,.•s
v cc 4 I
°� Y. N
cc
•
\ACA110
-. 4-,3-93 - { SPRUCE STREET
J� .aan HOR 'LAI QaQ p� a cd
j \�G I.1
139.90 '
19 ° 10 o ce
illT I' a
a
u. \.7 A m
),/ ALDER STR ET inn ill k •yyy
gEaa
cn
r 6 1111111 44+�
o C 30REN
k.
N
vAc T..s.-.0 AR srnccA
YY �o ±iiir - CEDAR STREET _ 11
I
36 K�, adQ� , $ > >�►JYe?P1 ''''
' 'j rm
�R� H AVENUE vo� FLORENCE AVENUE if
_ o`er 1 LAWRENCE AVENUE
al
1 28 �� „_, 4 A goy 2
/ LAKE AVE �+co)
NNE
I I
' CARROLL "a1
II,•
0 A rs
a 3
AVE 1 hg
. Alliiii Eli
Pc" IIF- AI III
MAPLE 5T. STEVENS AV �•
.2—N I 3—N w 2 NEE 5�,�l / ill 4
— 11.11N4) O > I 2•• ,�� RAILROAD .I1111� In/ NM �i Q
ov
4 q
'I'- ^
Ei
.1 r_-c-d I;.11)
I_I : ,• •IN.:._.li: Vj
•
...._.,,::::,:.„..,
...„... ::::.....,--_7::-=il!::1:.1.:!,:,
11111'1,. .•�.
...-::........„-:;;;.::-
, . __ . •: ! ......
SEE MAP ABOVE
if.-ig„ter.+;..friC�,
MUMSCAM A.19101.71
NOT TO SCALE ,j
The site soils are mapped by the Soil Conservation Service as Dick loamy sand. These soils
have a standard profile of loamy sand to a minimum of 60 inches in depth. They are
excessively drained and according to the Soil Survey have a permeability range of 6 to 20
inches per hour. However,Table III-3.1 of the Technical Manual provides an infiltration
rate of 2.41 inches per hour for loamy sand and this was used in the hydrologic modeling for
the site.
IV. OFF-SITE ANALYSIS
No off-site water currently impacts the project site.
V. STORMWATER RUNOFF CONTROL FACILITIES
The Technical Manual identifies 11 minimum requirements that must be addressed in all
stormwater management plans. These requirements are identified,described and addressed
below. Minimum Requirement#1 is Erosion and Sediment Control and that is addressed in
Section IX of this report(Large Parcel Erosion and Sediment Control Plan).
A. Minimum Requirement#2: Preservation of Natural Drainage Systems
[Technical Manual-Natural drainage patterns shall be maintained, and discharges from the
site shall occur at the natural location, to the maximum extent practicable.
Objective: To preserve and utilize natural drainage systems to the fullest extent because of
the multiple stormwater benefits these systems provide.]
As described above,topography slopes toward the southwest corner of the property at a
grade of approximately 3 %. However,based on the soil types typical of the Dick Series,
runoff from the site is currently very low. This stormwater plan proposes collection,
treatment and infiltration of the runoff caused by the development,thereby preserving the
natural drainage pattern.
B. Minimum Requirement#3: Source Control of Pollution
[Technical Manual-Source control BMPs shall be applied to all projects to the maximum
extent practicable. Source control BMPs shall be selected, designed, and maintained
according to an approved manual.
Objective: The intention of source control BMPs is to prevent stormwater from coming in
contact with pollutants. They are a cost-effective means of reducing pollutants in
stormwater, and therefore should be a first consideration in all projects.]
The only anticipated on-site pollutant source will be the access road. Runoff from the road
will be collected and treated in a bioswale adjacent to the access road. Sheet CO3 shows
Stormwater Site Plan 2 May 4,2001
Block 21;Irving Park Addition
proposed stormwater control and treatment improvements. The recommended grass seed
mix(hydroseeding preferred)for the bioswale is provided on Sheet C04.
C. Minimum Requirement#4: Runoff Treatment BMPs
[Technical Manual-All projects shall provide treatment of Stormwater. Treatment BMPs
shall be sized to capture and treat the water quality design storm, defined as the 6-month, 24-
hour return period storm. The first priority for treatment shall be to infiltrate as much as
possible of the water quality design storm, only if site conditions are appropriate and
groundwater quality will not be impaired.
Objective: The purpose of runoff treatment is to reduce pollutant loads and concentrations
in stormwater runoff using physical, biological, and chemical removal mechanisms.]
See Item C above.
D. Minimum Requirement#5: Streambank Erosion Control
[Technical Manual-Stormwater discharges to streams shall control streambank erosion by
limiting the peak rate of runofffrom individual development sites to 50 percent of the existing
condition 2-year, 24-hour design storm while maintaining the existing condition peak runoff
rate for the 10-year, 24-hour and 100-year, 24-hour design storms.
Objective: To reduce streambank erosion that results from increased runoff due to
development. The standard is intended to reduce the frequency and magnitude of bankfull
flow conditions, which are highly erosive and increase dramatically as a result of
development.]
Typically,hydrologic analysis is used to design a stormwater control system that limits site
runoff to less than pre-development conditions. In this case,since infiltration is proposed as
the permanent stormwater control system,pre-existing conditions are not relevant. The
proposed system is based on infiltrating all of the stormwater runoff during a 100-year,24-
hour storm event.
Hydrologic modeling has been performed to size the infiltration pond(see Appendix A for
modeling assumptions and results). The modeling was performed using the computer model
HydroCad. For modeling purposes, it was assumed that all of the access roid runoff plus the
runoff from the individual building sites would go to the infiltration pond. Based on the
Technical Manual's Table III-1.3, impervious surface coverage of 33%can be assumed for
single-family residential development at a density of 2.8 dwelling units per acre(2.85 acres/8
units). The remaining 67%of each building site is assumed to be landscaped with runoff
calculated assuming 75% lawn in good condition.
For the purpose of the design of the system for this site, a permeability of 2.41 inches per
hour(0.003 feet per minute)has been used.
Stormwater Site Plan 3 May 4,2001
Block 21;Irving Park Addition
Based on a 100-year storm event(2.75 inches of precipitation), a pond with bottom
dimensions of 20 feet x 120 feet and side slopes of 2 horizontal:1 vertical and a depth of 2
feet will be required. That configuration will provide for one foot of freeboard during the
100-year storm event.
The pond configuration and location is shown on Sheet CO3. The pond should be seeded
(hydroseeding preferred)with the recommended grass seed mix provided on Sheet C04.
E. Minimum Requirement#6: Wetlands
[Technical Manual-Stormwater discharges to wetlands must be controlled and treated to
the extent necessary to meet the State Water Quality Standards, as appropriate. Discharges
to wetlands shall maintain the hydroperiod and flows of existing site conditions to the extent
necessary to protect the characteristic uses of the wetland. Created wetlands that are
intended to mitigate for loss of wetland acreage,function and value shall not be designed to
also treat stormwater. In order for constructed wetlands to be considered treatment systems,
they must be constructed on sites that are not wetlands and they must be managed for
stormwater treatment. Stormwater treatment BMPs shall not be built within a natural
vegetated buffer, except for necessary conveyance systems as approved by the local
government.
Objective: To ensure that wetlands receive the same level of protection as any other waters
of the state. Wetlands are extremely important natural resources which provide multiple
stormwater benefits, including groundwater recharge,flood control, and streambank erosion
protection. They are easily impacted by development unless careful planning and
management are conducted. Wetlands can be severely degraded by stormwater discharges
from urban development due to pollutants in the runoff f'and also due to disruption of natural
hydrologic functioning of the wetland system. Changes in water levels and the duration of
inundations are of particular concern.]
No wetlands have been identified at the project site.
F. Minimum Requirement#7: Water Quality Sensitive Areas
[Technical Manual- Where local governments determine that the Minimum Requirements do
not provide adequate protection of water quality sensitive areas, either on-site or within the
basin, more stringent controls shall be required to protect water quality.
An adopted and implemented basin plan (Minimum Requirement#9) may be used to develop
requirements for water quality sensitive areas that are tailored to a specific basin.
Objective: To ensure protection of water quality in sensitive areas.]
No basin study is available for the analysis of impacts to potential water quality sensitive
areas. The proposed stormwater control facilities are designed to meet the requirements of
Stormwater Site Plan 4 May 4,2001
Block 21;Irving Park Addition
the Technical Manual for treatment and infiltration of stormwater runoff generated by the
development.
G. Minimum Requirement#8: Off-Site Analysis and Mitigation
[Technical Manual-All development projects shall conduct an analysis of off-site water
quality impacts resulting from the project and shall mitigate these impacts
Objective: To ensure that future impacts from the project will be controlled and/or existing
impacts will not be aggravated by the project.]
Since the proposed on-site stormwater control facilities will treat and infiltrate stormwater
runoff,thereby mimicking existing site conditions,it is anticipated that no mitigation will be
necessary off site.
H. Minimum Requirement#9: Basin Planning
[Technical Manual-Adopted and implemented watershed-based basin plans may be used to
modem any or all of the Minimum Requirements,provided that the level of protection for
surface or groundwater achieved by the basin plan will equal or exceed that which would be
achieved by the Minimum Requirements in the absence of a basin plan.
Objective: To promote watershed-based planning as a means to develop and implement
comprehensive water quality protection measures. Primary objectives of basin planning are
to reduce pollutant loads and hydrologic impacts to streams and wetlands.]
No basin studies are available related to stormwater for this area.
I. Minimum Requirement#10: Operation and Maintenance
[Technical Manual-An operation and maintenance schedule shall be provided for all
proposed stormwater facilities and BMPs, and the party(or parties) responsible for
maintenance and operation shall be identified.
Objective: To ensure that stormwater control facilities are adequately maintained and
operated properly.]
Operation and maintenance of all stormwater control facilities, including erosion and
sediment control BMPs are discussed in Section X of this report(Maintenance and
Operations).
J. Minimum Requirement#11: Financial Liability
[Technical Manual-Performance bonding or other appropriate financial instruments shall
be required for all projects to ensure compliance with these standards.
Stormwater Site Plan 5 May 4,2001
Block 21;Irving Park Addition
Objective: To ensure that development projects have adequate financial resources to fully
-� implement stormwater management plan requirements and that liability is not unduly
incurred upon local governments.j
The property owner(s)will assume all fmancial liability associated with the operation and
maintenance of the temporary erosion and sediment control and permanent stormwater
quality control facilities.
VI. SPECIAL REPORTS AND STUDIES
No special reports or studies are available for the site.
VII. BASIN AND COMMUNITY PLANNING AREAS
No basin studies are available related to stormwater for this area.
VIII. OTHER PERMITS
This report is being prepared to accompany a Master Land Use Application Form for a
Stormwater Permit. Building and septic permits will be obtained from the County by the
individual lot owners.
IX. LARGE PARCEL EROSION AND SEDIMENT CONTROL PLAN
Since the proposed new development involves creation of greater than 5,000 square feet of
impervious surfaces and greater than one acre of land disturbing activities,it requires a Large
Parcel Erosion and Sediment Control Plan("LPESC Plan"). This section of the Stormwater
Site Plan, in conjunction with Sheets CO2 and C04 of this report,constitutes the LPESC Plan
for this development.
The purpose of the LPESC Plan is to provide for the interception and treatment of all
potential silt-laden runoff that could occur during clearing,grading,construction,and site
stabilization. The goal of the LPESC Plan is to assure that no silt-laden runoff leaves the site
during construction and site stabilization.
Sheet CO2 identifies Erosion and Sediment Control Best Management Practices(BMPs)to be
used during construction and site stabilization at the site. Sheet C04 provides construction
details for the BMPs. Erosion and Sediment Control BMPs are designed first and foremost
to prevent erosion and secondly to deal with sediment produced from unavoidable erosion.
The Technical Manual identifies 15 minimum requirements for erosion and sediment control
that must be addressed in an LPESC Plan. Each of these requirements is described and
addressed below.
Stormwater Site Plan 6 May 4,2001
Block 21;Irving Park Addition
A. ESC Requirement#1: Stabilization and Sediment Trapping
[Technical Manual-All exposed and unworked soils shall be stabilized by suitable
application of BMPs. From October 1 to April 30, no soils shall remain unstabilized for
more than 2 days. From May 1 to September 30, no soils shall remain unstabilized for more
than 7 days. Prior to leaving the site, stormwater runoff shall pass through a sediment pond
or sediment trap, or other appropriate BMPs.]
The following BMPs will be used at the site to meet this requirement:
• Mulching(with straw)is to be used for all exposed areas of the site during
construction and after seeding to protect and insulate geminating seeds. The straw
application rate shall be 75 to 100 pounds or two to three bales per 1,000 square feet
of exposed area. The depth of application shall be a minimum of two inches. Straw
mulch must be kept moist or will be tacked down to prevent it being blown away by
wind.
• Gravel base on the access road shall be applied as soon as feasible after grading.
• Soil stockpiles will be stabilized or protected with sediment trapping measures to
prevent soil loss.
B. ESC Requirement#2: Delineate Clearing and Easement Limits
[Technical Manual-In the field, mark clearing limits and/or any easements, setbacks,
sensitive/critical areas and their buffers, trees and drainage courses.]
Silt fencing will be used for protection of adjacent properties(as discussed in the next
section).
C. ESC Requirement#3:Protection of Adjacent Properties
[Technical Manual-Properties adjacent to the project site shall be protected from sediment
deposition.]
The following BMPs will be used on-site to meet this requirement. .
Silt Fencing
Silt fencing shall be installed as shown on Sheets CO2 and C04 to prevent sediment carried
by stormwater runoff from leaving the site.
Filter fabric shall be purchased in a continuous roll cut to the length of the barrier to avoid
use of joints. When joints are necessary, filter cloth shall be spliced together only at a
support post,with a minimum six-inch overlap,and both ends securely fastened to the post.
Stormwater Site Plan 7 May 4,2001
Block 21;Irving Park Addition
Posts shall be spaced a maximum of six feet apart and driven securely into the ground a
minimum of 30 inches,where physically possible.
A trench shall be excavated approximately 8 inches wide and 12 inches deep along the line of
posts and upslope from the barrier. The trench shall be constructed to follow the contour.
D. ESC Requirement#4: Timing and Stabilization of Sediment Trapping Measures
[Technical Manual-Sediment ponds and traps,perimeter dikes, sediment barriers, and
other BMPs intended to trap sediment on-site shall be constructed as a first step in grading.
These BMPs shall be functional before land disturbing activities take place.]
The silt fencing will be constructed and installed prior to all other site disturbing activities.
E. ESC Requirement#5: Cut and Fill Slopes
[Technical Manual- Cut and fill slopes shall be designed and constructed in a manner that
will minimize erosion. In addition, slopes shall be stabilized in accordance with ESC
Requirement#1.]
Cut and fill slopes will be constructed around the infiltration pond and bioswale. Slopes will
be seeded and mulched as described in"A"above.
F. ESC Requirement#6: Controlling Off-Site Erosion
[Technical Manual-Properties and waterways downstream from development sites shall be
protected from erosion due to increases in the volume, velocity, and peak flow rate of
stormwater runoff from the project site.]
No increase in the volume,velocity or flow rate of runoff is anticipated from the project site.
G. ESC Requirement#7: Stabilization of Temporary Conveyance Channels and
Outlets
[Technical Manual-All temporary on-site conveyance channels shall be designed,
constructed, and stabilized to prevent erosion from the expected velocity offlow from a 2-
year, 24-hour frequency storm for the developed condition. Stabilization adequate to prevent
erosion of outlets, adjacent streambanks, slopes and downstream reaches shall be provided
at the outlets of all conveyance systems.]
No temporary conveyance channels are anticipated.
Stormwater Site Plan 8 May 4,2001
Block 21;Irving Park Addition
H. ESC Requirement#8: Storm Drain Inlet Protection
[Technical Manual-All storm drain inlets made operable during construction shall be
protected so that stormwater runoff shall not enter the conveyance system without first being
filtered or otherwise treated to remove sediment.]
Straw bales will be installed in the bioswale as shown on Sheets CO3 and C04 until the grass
is established to prevent erosion of the swale and to protect the cross-culvert leading to the
infiltration pond.
I. ESC Requirement#9: Underground Utility Construction
[Technical Manual- The construction of underground utility lines shall be subject to the
following criteria.
Where feasible, no more than 500 feet of trench shall be opened at one time. Where
consistent with safety and space considerations, excavated material shall be placed on the
uphill side of trenches.
Trench dewatering devices shall discharge into a sediment trap or sediment pond.]
No more than 500 feet of trench shall be open at any time during underground utility
construction. No dewatering is anticipated at this site.
J. ESC Requirement#10: Construction Access Routes
[Technical Manual- Whenever construction vehicle access routes intersect paved roads,
provisions must be made to minimize the transport of sediment(mud) onto the paved road If
sediment is transported onto a road surface, the roads shall be cleaned thoroughly at the end
of each day. Sediment shall be removed from roads by shoveling or sweeping and be
transported to a controlled sediment disposal area. Street washing shall be allowed only
after sediment is removed in this manner.]
A stabilized construction entrance will be provided as shown on Sheets CO2 and C04 in order
to prevent erosion by construction vehicles and tracking of sediment off-site.
Material used for the stabilized construction entrance shall be quarry spalls, four inches to
eight inches in size. The rock pad shall be at least 12 inches thick and 100 feet long;the
width shall be the full width of the vehicle ingress and egress area.
Additional rock shall be added periodically to maintain proper function of the pad.
Any sediment that is transported to paved areas will be swept and deposited in a controlled
area.
Stormwater Site Plan 9 May 4,2001
Block 21;Irving Park Addition
I
K. ESC Requirement#11: Removal of Temporary BMPs
[Technical Manual-All temporary erosion and sediment control BMPs shall be removed
within 30 days after final site stabilization is achieved or after the temporary BMPs are no
longer needed. Trapped sediment shall be removed or stabilized on site. Disturbed areas
resulting from removal shall be permanently stabilized]
The silt fencing will be removed within 30 days after the site is stabilized. All disturbed
areas resulting from the removal of the BMPs shall be stabilized.
L. ESC Requirement#12: Dewatering Construction Sites
[Technical Manual-Dewatering devices shall discharge into a sediment trap or sediment
pond.]
No dewatering is anticipated during construction at this site.
M. ESC Requirement#13: Control of Pollutants Other Than Sediment on Construction
Sites
[Technical Manual-All pollutants other than sediment that occur on-site during
construction shall be handled and disposed of in a manner that does not cause contamination
of stormwater.]
Other potential pollutants besides sediment associated with construction activities include
chemicals(pesticides, fertilizers,paints,oils,gasoline,etc.)and wastes such as paper,wood,
concrete debris, garbage, and sanitary wastes. These must be controlled to prevent damage
to neighboring properties and off-site watercourses. Although the construction of the access
road and installation of underground utilities are not anticipated to be a source of other
pollutants, it is anticipated that this Stormwater Site Plan will be applied to development of
the individual lots and therefore the following best management practices are recommended.
Good housekeeping practices are the most economical and effective way to control these
potential pollutants. Weather—resistant storage will be provided for chemicals to be used on-
site. Wastes will be removed promptly and will be disposed of at authorized facilities.
Storage sheds and dumpsters will be regularly monitored for leaks and repaired as necessary.
Workers will be reminded about proper storage and handling of materials.
Washout from concrete trucks will be disposed of into a designated area that will later be
backfilled(slurry pit),or in an area where the material can harden,be broken up and then put
in a dumpster. In no case will concrete washout occur in a location subject to surface water
runoff or closer than 50 feet from a storm drain.
Storniwater Site Plan 10 May 4,2001
Block 21;Irving Park Addition
N. ESC Requirement#14: Maintenance
[Technical Manual-All temporary and permanent erosion and sediment control BMPs shall
be maintained and repaired as needed to assure continued performance of their intended
function. All maintenance and repair shall be conducted in accordance with an approved
manual.]
Operation and maintenance of all stormwater control facilities, including erosion and
sediment control BMPs,are discussed in Section X of this report(Maintenance and
Operations).
O. ESC Requirement#15: Financial Liability
[Technical Manual-Performance bonding, or other appropriate financial instruments, shall
be required for all projects to ensure compliance with the approved erosion and sediment
control plan.]
The developer/property owners assume responsibility for the continued maintenance of the
erosion control BMPs identified in this report.
X. MAINTENANCE AND OPERATIONS
The major reason for BMP failure is poor maintenance. For this site, all of the Large Parcel
Erosion and Sediment Control BMPs will be inspected regularly,particularly before,during
and after a major storm event. In addition,a routine"end of day check"will be implemented
during construction to make sure that all control practices are working properly,and to repair
any that are not,prior to leaving the site unsupervised overnight or over a weekend.
All temporary erosion and sediment control measures shall be removed within 30 days after
fmal site stabilization is achieved or after the temporary BMPs are no longer needed.
Trapped sediment shall be removed or stabilized on-site. Disturbed soil areas resulting from
removal shall be permanently stabilized.
Straw mulching:mulched areas shall be checked periodically,especially following severe
storms. Additional straw shall be added and damaged areas shall be repaired as necessary.
Seeded areas: seeded areas shall be inspected for failure and reseeded as necessary. A
follow-up survey shall be made after one year and areas shall be reseeded as necessary.
Construction access road:the construction entrance and exit shall be maintained in a
condition that prevents tracking of mud onto the public rights-of-way. Periodic top dressing
with two-inch stone,as conditions demand, shall be made. All materials spilled,dropped,
washed,or tracked from vehicles onto roadways or into storm drains shall be removed
immediately.
Stormwater Site Plan 11 May 4,2001
Block 21;Irving Park Addition
Filter fence:the filter fence shall be inspected immediately after each rainfall,and at least
daily during prolonged rainfall, and repaired as necessary. Sediment shall be removed when
it reaches approximately one-third the height of the fence,especially if heavy rains are
expected. Any sediment deposits remaining in place after the filter fence is no longer needed
shall be dressed to conform to the existing grade,prepared and seeded.
Straw bales: straw bale barriers shall be inspected immediately after each runoff-producing
rainfall and at least daily during prolonged rainfall. Close attention must be paid to the repair
of damaged bales,end runs,and undercutting beneath bales. Necessary repairs shall be made
promptly. Sediment deposits shall be removed after each runoff-producing rainfall. They
must be removed when the level of deposition reaches approximately one-half the height of
the barrier. Any sediment deposits remaining in place after the straw bale barrier is no longer
required shall be dressed to conform to the existing grade,prepared and seeded.
Bioswales: the vegetated bioswales must be mowed regularly to promote growth and
pollutant uptake. Grass cuttings must be removed promptly and disposed in a way so that no
pollutants can enter the infiltration pond.
Sediment should be removed from the bioswale when they build up to 6 inches at any spot,
cover biofilter vegetation,or otherwise interfere with biofilter operation. Use of equipment
like a Ditch Master is recommended over a backhoe or dragline. If the equipment leaves
bare spots they must be re-seeded immediately.
Bioswales must be inspected periodically,especially after periods of heavy runoff. Sediment
removal and reseeding should be done as necessary. Fertilizer use must be done carefully to
avoid impacts to groundwater.
Homeowners in this development should be made aware of the maintenance
recommendations in this report.
Infiltration Pond: the infiltration pond should be inspected on a monthly basis,and more
frequently if a large storm occurs,when it is first placed into service. Thereafter,once it is
determined that there are no potential sediment problems, inspection can be reduced to a
semiannual basis with additional inspections following the occurrence of a large storm(e.g.
approximately 1 inch in 24 hours).
Establishing a healthy stand of vegetation on the basin side slopes and floor is important as it
will not only prevent erosion and sloughing,but will also provide a natural means of
maintaining relatively high infiltration rates. Inspection of the basin should include an
evaluation of the vegetation and follow-up with reseeding of bare spots. Grass bottoms in
infiltration basins seldom need replacement since grass serves as a good filter material.
Stormwater Site Plan 12 May 4,2001
Block 21;Irving Park Addition
APPENDIX A
RESULTS OF COMPUTER SIMULATIONS OF STORM EVENTS
AND SIZING OF STORMWATER FACILITIES
- Data for Wood: 100yr/postdev/entire site/pond Page 1
TYPE IA 24-HOUR RAINFALL= 2.75 IN
Prepared by Colette M. Kostelec, P.E. 4 May 01
HvdroCAD 5.11 001496 (c) 1986-1999 Applied Microcomputer Systems
WATERSHED ROUTING ---------- ----------- --- ------
O
\/(--
SUBCATCHMENT n REACH Q POND Ej LINK
SUBCATCHMENT 1 = Post-development -> POND 1
POND 1 = Infiltration Pond 20x120x2 ->
Data for Wood: 100yr/postdev/entire site/pond Page 2
TYPE IA 24-HOUR RAINFALL= 2.75 IN
Prepared by Colette M. Kostelec, P.E. 4 May 01
HvdroCAD 5. 11 001496 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCHMENT 1 Post-development
PEAK= .59 CFS it 8.02 HRS, VOLUME= .25 AF
ACRES CN SBUH METHOD
.25 98 access road TYPE IA 24-HOUR R
.86 98 33% imperv. bldg sites RAINFALL= 2.75 IN
1 .74 68 landscaped areas SPAN= 0-48 HRS, dt=.1 HRS
2.85 80
Method Comment Tc (min)
CURVE NUMBER (LAG) METHOD Segment ID: 8.8
L=400' s=.03 '/'
SUBCATCHMENT 1 RUNOFF
Pot-dmv Iopmmnt
.55 - AREA= 2 .85 AC
.50 - Tc= 8 . B MIN
CN= 80
.45
SBUH METHOD
35 - TYPE IA 24-HOUR
RAINFALL= 2. 75 IN
� .30 -
PEAK= .59 CFS
25 - a 6 .02 HRS
CD .20 - VOLUME= . 25 AF
r --J
. 1 5 -
. 1 0 -
.05 -
0 .00 —
Es) m Ln m m i ) m in
( t N rr) 01 Cr �f
TIME CIour-s)
Data for Wood: 100yr/postdev/entire site/pond Page 3
TYPE IA 24-HOUR RAINFALL= 2.75 IN
Prepared by Colette M. Kostelec, P.E. 4 May 01
HydroCAD 5. 11 001496 (c) 1986-1999 Applied Microcomputer $ystems
POND 1 . Infiltration Pond 20x120x2
Qin = .59 CFS @ 8.02 HRS, VOLUME= .25 AF
Qout= . 15 CFS @ 17.95 HRS, VOLUME= .25 AF, ATTEN= 75%, LAG= 595.8 MIN •
ELEVATION CON.AREA INC.STOR CUM.STOR WET.AREA STOR-IND METHOD
(FT) (SF) (CF) (CF) (SF) PEAK STORAGE = 2442 CF
0.0 0 0 0 0 PEAK ELEVATION= 1.0 FT
.2 2513 168 168 2513 FLOOD ELEVATION= 2.0 FT
.4 2627 514 681 2633 START ELEVATION= 0.0 FT
.6 2742 537 1218 2753 SPAN= 0-48 HRS, dt=.1 HRS
.8 2858 560 1778 2875 Tdet= 215.6 MIN (.25 AF)
1 .0 2976 583 2362 2999
1 .2 3095 607 2969 3125
1 .4 3215 631 3600 3251
1 .6 3337 655 4255 3380
1 .8 3460 680 4935 3509
2.0 3584 704 5639 3640 ,
a ROUTE INVERT OUTLET DEVICES
1 P 0.0' EXFILTRATION
V= .003 FPM over SURFACE AREA
POND 1 INFLOW 8. OUTFLOW
Infiltration Pond 20x120x2
55 STOR-IND METHOD
.50 - PEAK STOR= 2442 CF
45 - PEAK ELEU= I FT
.40 - QIn= .59 CFS
co-
.35 - Qout= . 15 CFS
`U 3@ LAG= 595. 8 MIN
.25 -
CD 20 -
1i . 15 - -- ----
. 10 - I' �1
.05 - 1 i1 Li,
m li 1 m - CV rn r,r) m[T V'-cr
TIME (hours)
: .
so
1-
A
a
Q
a
DIII
\ .'11
1VD 1929
RVAL = 1. 00'
1
1RESI
PERFORMED BY FIELD TRAVERSE
y SECOND ELECTR❑NIC TOTAL
/ ITE AND STEEL TAPE.
El
/ \J 16, T. 30 N. , R. 1 W. , WM.
gpy2
// O�+vjb
WITH CAP 'A. WOOD PLS 23911' a o ,1,,
c,
�POGRAPHIC CONTOUR i p a
A
........ i REE 1 h R
r k H
i
0.
�— �NA
A ' %
U VAL i
D EASEMENT
WATER MAIN
. J NDERGR❑UND PHONE CABLE
UGT NDERGR❑UND POWER
q
FLORENCE % . it
AVE. C..,g , vtAVED ROAD
—I D
��7 3
rl 1-1
z = 5 0 DAIS XAY42001
G1 100' 150'
� SCAM AS SHOWN
col
4
I
et. 4
a
i g h A
a
lb
/ / O R WITH CAP 'A. WOOD PLS 2391 1' S
�oo
TDP❑GRAPHIC CONTOUR � OR a
� TREE 1 A
h
1 / N
1
( ; OF STRAW BALE
v EE SHEET CO3
1 CI a
1 rn N
gi
A al O O
J c 1 (
U VAULT
■ 'AD EASEMENT R
8' WATER MAIN y
J <UNDERGROUND PHONE CABLE
I/1 urTUNDERGR❑UND POWER
FL O R E N C E AAA**,�����,���'��►�'S I LT FENCE
A V E.
4r1W"
*���:;4w4,- 7.4,,PAVED ROAD O 64
70
rr i z �, 1" = 5 0'
`� —1 L 1 DAM MAY42001
100' 150' ASS
CO2HOIVN
s
_ :Ila
4
t
i .i
M
44
F g.
1
f'
/ Q
q2
/ Ai
TH CAP 'A. WOOD PLS 23911' S M
a
GRAPHIC CONTOUR 0 ti 3
_....., ( :
h
1 N
1
v 19s\ o a
NE
�LVERT AND SWALE OUTLETS TO POND c'H i g
C e 4) Ph
�_ " :' - GRADE
" W BALE BARRIER (SEE SHEET C04)
R ti 1
U A
y
$FLORENCE 40,w T % f**
CO N AVE. ,#,� 0A j�� q.4•Aisi•is D ROAD i N N v� 7 ` D ROAD (SEE SHEET C04)
Or Cf
rn 1-1 ,S. = 5 0' V
m z
—I 0 100' 150' n12 MAr4 To01
SCAM AS SHOWN
tel:
CO3
4
A
�-- Qo
,/// J MIX FOR BIOSWALE & POND
o
R
c��5 •o:�1: 'on. fescue (Festuca rubra) 40%
II
AZCIZ3.0 n niol bentgross (Agrostis tenuis) 20%
•�: •� ed hairgrass (Dechampsia cespitosa) 20% 41
..o .og3. o$1, 0 . g
-;•��p������.• adion bluegrass (Poo compressa) 10%
•^=f: 4 003 , og3 d$3 d <e clover (Trifolium hybridum) 10%,o o.o• .-o 00 0q0, 00. g.
• •: �23dow fescue (Festuca protensis) 40% glik
'`*: dow foxtail (Alopecurus protensis) 20% ;::1
12"MIN op bentgrass (Agrostis alba) 20% o
. rush (Juncus effusus) 10 %
4"to 8"OUARRY SPALLS side bentgross 10
PROVIDE FULL
INGRESS/EGI
CONSTRUCTION ACCESS ROA
q2
4'-'--A ' ova
as
1 h N
R
,it I II 11_ t 1 I III I i l-1 I I-1 11-
ril c4 is k
M id
1 ma q
n o
• Y.
v.
ti /W V- W V.
W .'e.
'".`/0 ,/ W 4"-6" QUARRY SPALLS
W vL �/s. "-
111 ELEVATION
W W
Y V- Y
I.
W 1 rNw W
3 FT N' / a* V. W �/ R CULVERT; 12" FOR SWALE A
64SE- /..,.,_
'TION DAM MAE41 zoo
BIOSWALE CROSS-SECTION 'WALE scAut AS SHOWN
'OND SWIM
C04
au-usr 89£86VM VM'Alm )Nonatax NV7d70?LLNOO ri
QQ ^'
• snout- ➢UXI UAP7SNMO.L2NOd NOLLIOQVYXVdDAlIi1Xl i ` v
pCP6 YAl YAY6NMQL1YQY CWOWAN3AOJsIarrrt .LNENIGUS O
OfY=nd IzxO07a
a .., ..... , g'd"J178LSUY7YHLl8'll117 a00M O70N NV7d SLIS XSLVMIYXO.Ls 4'NOISO?Ig 1 11 V
u� s eoWxv,r 89£86VM VM ALNf00NOSN9dd9£
srrslLYYSK)= CINEISAMICALM al NOLLIQQVYXVd°MAXI Nd7d ! 1
+911,6rr Y21.4644402.11,04 GOl o Re ItX007s HLISONLLSIX�7 rO\
a o a Ti=L$OY NHLL87I0.7 nm V7
r Nd ELLIS XS lYXO.L LVMs 1 1 1 U
w
N
K
>J Z f`) c
KI 2 N w
~I- J
Q ULi s 6 ce Cu
LiZ- .r 0 7
W 0I- Cu 0 F- Z W
.1--_, - o pp
p al
WW Z Q U Z CL Cu
g JI- 0 .Uy I- a Cu a 0 .r
WN
CZ~ U W K CN II 0ZZ Q W in
WoQ I Cu N 1.- l7 to-I to w ,o a a OC CZ a II
Cu W WLW p Li W 3 W W W
Q > 0 aNH 3 6. W Cu ca >
I-" W jN q
HtiU O U l7 lD
W Z Z 7 .. 7
7H N---1[] >-.wW W Cu ._ .. Li .-. ./i
n
F- F- - 1-
I- (40 ', W aO A in La W Li W W d 47
�• W-r y"'Qy 0, Z W W II U
U ~ y .. LA to I Crs I I J p T—
• 7 J p
Ln
11 1
1
c. 195- I
fi
oo oc 195 v 1--� J
_IW WO N.V' III
Cu11 s.
a
w / CO
CO
w ce .r
a • _,H
CZ
w �.
U
u • _
_�Cu / I—
>
LI
F- L` L_ t :(• C'� (lJ II
W
v p J s. L. d
0
co to N
W Eli N U IL
In Ce
.- m L7 Nr(Op CO •Q ^ . I '
\\)
Q •. .M-I I "" • I .
CO h C]
at n
MI 1111a 13
-- "'n.a _ FLAMINGO
• STREET
LU
U
z
Li U
>
a a
J
L.
/ '
• nowtl'` os°"e")xvi $106vM vm;i.wno.9nrOSItali f Atrld 7OMINOD 1 N
sum(09uac ONHSNMQtdXOa NOLLICKIV IVd°NM!
"'�"'" "" Y; avoaaaIaa1siarrn !z]rJ07& . Argfri IQgS O
4, .,, -... Iry soy xaua a00M Q7 nmaaus aratvtislvaraLs HOIS020.
En 0
M t—
N Li
0 J
J en
a a
a' U
a D
O ❑ W K
3 Z J ❑ 2
Q ❑U m M Z d M Z.
O o
u 3 v 1- a a a p
• x ¢� w > j Q a in
U a Kw X W ❑ ❑ o
a H w w w a' K w a
o-. o W w N W Z W W H W I I
W O a a -I >
a I-- d W Q M 7 M N 6a.Q Ce
1 qq—
XI ❑ 0 Z ❑ a 0
w ZZO cn ZZZW Z a ~ N Fcc N . . r -
^ aW WNNNp0 N CC U . . r O mX X O XXXax a in w w J Q a w W W a W d
J I U
II ' II
Lt1—
•
u 195-, g
• • 16'1'
ii
!195 ,' �
g, i 1
\`� I.W / lig N v
11)
A
lli
yi `� %wu •
0 , g.
U
i
i' li).Pc
LkoO 'iJiLi4'
O '•
,.,, ,... s, a 1..,&4.&4.4.4w11). .____
IPI I,I,I,sJ,OSII•
'as Isla l� I,I�,I,I,.r,./V)A
►IIIIII�
�� rsts e` FLAMING❑
'SW STREET
w
z w w.
o ¢
J
lL
•
8E86V VAt;I.1.1003NOSN 91gf 1W7d 70 03 il i (�.ttt anm sncacu Lxal Noura Ta�� ai�l61hW?IOLS Otuna(reOat QVOYAWEE ISICIDIC zomtV�m� �i�t LN �afl kV)tIOYOPOd QOOM QONNYNV7dWS X£LLVAtJ17ALS
aroI v ... .,Far S'd 978IdO31 71,8GIC7CO
13
Z
❑ a
a 0
U
I-0
w
m 1- _
7 W N V O
Cu J 0
N Ii
LI
al 2
0 I-
o
Q' U• ,
" w a �0 7 "'¢ a j II
a❑ w 0 UU s w w
> >
a a °
In
2' I- 1,4
/- (4 1-1- Z N .--1
o
¢W
�' .Zi '-' N ¢N N (4 LI
.Z-,• Li
.- F- ❑ o arn
I-Li 0
Cu o aw o o (4 o N
\ X X OL Vl Cu d' X p_'
(a N W W d K v a d Li O. d
z :• U
•
G a
•.cv
]95-- N
/
•
pZ uice' , z g
y i• — 111 r
M'/6
simaer
(��y7]
III1iipJA$!
limiLi
%.,........74).Wr z iiir 1111. 1
,k fi. i
0
U- OA\I
i�i��'ii
vaism1� ItSW
•
IIIIIIIIIIIIIti
IIM
—"•""C4zil4OgED----"'nr"
►$ S�� FLAMING❑
,�I�I�V STREET
w •
u
z
ww
o
J
L_