HomeMy WebLinkAbout02946 - Technical Information Report - Drainage 1
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Section 1 Project �'
l.l Project Description .......................................................................... ]
1.2 Existing Conditions ......................................................................... 1
1.3 Developed Conditions...................................................................... 1
1.4 Challenging Site Parameters.......................................................... 2
Section 2 Core and Special Requirements........................................................3
2.1 Core Requirements..........................................................................3
2.1.1 Core Requirement#1 ........................................................3
2.1.2 Core Requirement#2........................................................3
2.1.3 Core Requirement#3........................................................4
2.1.4 Core Requirement#4........................................................4
2.1.5 Core Requirement#5........................................................4
2.2 Special Requirements......................................................................4
2.2.1 Special Requirement#1....................................................4
2.2.2 Special Requirement#2....................................................5
2.2.3 Special Requirement#3....................................................5
2.2.4 Special Requirement#4....................................................5
2.2.5 Special Requirement#5....................................................5
2.2.6 Special Requirement#6....................................................5
2.2.7 Special Requirement#7....................................................6
2.2.8 Special Requirement#8....................................................6
2.2.9 Special Requirement#9....................................................6
2.2.10 Special Requirement#10................................................6
2.2.11 Special Requirement#11 .................................................6
2.2.12 Special Requirement#12................................................ 7
2.2.13 Special Requirement#13................................................ 8
Section 3 Offsite Analysis.................................................................................9
3.1 Field Inspection...............................................................................9
Section 4 Inf'iltration and Water Quality Sizing Criteria and Results.......... 11
4.1 Infiltration Ponds .........................:................................................ 11
4.2 Water Quality Ponds..................................................................... 12
4.3 Filter Strips ................................................................................... 12
Section 5 Conveyance System Analysis and Design..................................... 13
5.1 Conveyance System....................................................................... 13
i Drainage Report
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List of Appendices
Appendix A....................................................... Contributing Area Maps
Appendix B.............................................. Infiltration Pond Calculations
Appendix C .........................................Water Quality Pond Calculations
Appendix D.......................................................Filter Strip Calculations
Appendix E ......................................... Conveyance System Calculations '
�i Drainage Report
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Section 1 Project Overvie��r
1. 1 Project Descrz:ptt:o��
The proposed King County� Re�io�lal C'.oiilmtulicati��ri� and Emei�genc�� Coordir:<lti:>?:
Center in Renton, WA, is intended to accommodate a full-time regional
communications staff, as well as an emergency coordination center for tempor<<���.
management of emergency response and communications. The Center will con� �
a single-story building with appurtenant parking and an approximately 200-foo
high communications tower. It is anticipated that approximately 4.40 acres of
existing surface area will be affected, resulting in 0.58 acres of new roadway, 0.��.
acres of landscaping, and 3.44 acres of new impervious surface (including parking
areas and the new building). The project is located within Zone 2 of an Aquifer
Protection Area within the City of Renton, and as such will comply with the
requirements and regulations set forth by the City of Renton Municipal Code, and
the King County Surface Water Design Manual (1990).
The project includes the installation of storm drainage pipes, filter strips, water
quality ponds, and inf"iltration ponds to convey and treat the stormwater from the
new impervious roadways, parking areas, and rooftops.
1.2 Existing Conditions
The existing property is located within the City of Renton in the vicinity of 2nd
Avenue NE and Monroe Avenue NE, southeast of the County maintenance facilities.
The site was apparently used as tank testing grounds during World War II, and is
currently used by King County Road Services Division as a storage and paint-stripe
testing area. The site is relatively flat, though the southern portion of the site is the
crest of a 250-foot high slope that descends toward the Cedar River. Much of the site
is currently wooded and overgrown with heavy vegetation. An existing paved
roadway cuts through the site. There are also several gravel foot paths across the
site.
The storm drainage from this property does not appear to leave the site via overland
flow. Field visits have indicated, and the geotechnical report have confirmed, that
the surface water inf"iltrates completely into the soil. Section 3: Offsite Analysis
contains a description of the downstream drainage conditions, and Section 2.2.12
describes the results of the Geotechnical Report prepared for this site.
1.3 Developed Conditions
In the developed condition, the property will have approximately 0.58 acres of ne���
roadway, 0.39 acres of landscaping, and 3.44 acres of new impervious surface
(including parking areas and the new building). Runoff from the roadway will be
treated for water quality in filter strips, and will be in�ltrated via drainage s�vales.
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Runoff from the new parking areas will be directed to water quality ponds through li
storm drain pipes, and will then be infiltrated via infiltration ponds. Runoff from
the roof of the proposed building will be routed directly to the infiltration ponds, as
pretreatment is not required.
1.4 Challenging Site Parameters
There are two site parameters that affect the location and size of the proposed
infiltration ponds. First, there are two existing 50-foot wide easements directly e<<
of the project site which accommodate a 16-inch and a 20-inch oil pipeline, owned E
Olympic Pipeline. The design of the eastern infiltration pond is intended to prevel�c
any changes in the groundwater elevation in the soil surrounding these pipelin��
Secondly, the steep slope to the south of the site is within 200 feet of the easter:
infiltration pond. Due to the high permeability of the existing soils and the eki5�i�;�
infiltration patterns of stormwater, the proximity of this western pond to the slopes
south of the site is not anticipated to affect the stability of the slope. See Section
2.2.11 for a discussion of the Geotechnical Report prepared for this site and the
infiltration pond locations near a steep slope.
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Section 2 Core and Special Requireinents
2.1 Core Requirements
2.1.1 Core ftequirement#1: Discharge at Natural Location
Requirement: All surface and storm cvater runoff from a project must be discharged
at the natural location so as not to be diuerted onto or away from downstream
properties, except that surface and storm runoff from new or existing irrapervious
surfaces subject to vehicular use or storage of chemicals should be discharged at the
location and in the manner whic�e cvill provide the most protection to the aquifer. The
manner in which runoff is discharged from the projecl site must not create a
significant aduerse impact to downhill properties or drainage systems.
There is no existing concentrated drainage flow away from the project site.
Currently, stormwater that falls on the site is in�ltrated into the ground. The
design for the proposed stormwater ma�agement facilities is to install infiltration
ponds which will mimic the existing infiltration process. Runoff will not be diverted
onto any downstream properties, nor will any existing runoff be diverted away from
downstream properties.
Runoff from the proposed impervious surfaces that are subject to vehicular use or
storage of chemicals will be routed to a treatment water quality pond prior to
infiltration. The water quality pond will be lined in order to prevent infiltration into
the aquifer during the treatment stage.
The project is not located within a Landslide Hazard Drainage Area, nor is it
adjacent to or containing Sensitive Areas Ordinance (SAO)-defined landslide, steep
slope, or erosion hazard areas.
The project is located within Zone 2 of an Aquifer Protection Area as defined by City
ordinance, and the methods of analysis and design are in compliance with those
standards set forth in Special Requirement#13: Aquifer Recharge and Protection
Areas.
2.1.2 Core Requirement#2: Offsite Analysis
Requirement: All proposed projects must su6mit an offsite analysis report that
assesses potential o�'fsite drainage impacts associated r.vith deuelopment of the project
site and proposes appropriate mitigations of those impacts.
See Section 3 for an Offsite Analysis of the proposed project area.
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2.1.3 Core Requirement#3: Runoff Control
Requirement: Proposed projects must prouide runoff control through d combination
o(pe�k rate rurzoff control and on-site biofillration. Proposed project rurioff resulting
from more than 5,000 sf of imperuious surface, and subject to uehicular use or storage
of chemicals, shall be treated prior to discharge from the project site by on-site
biofiltration measures as described in Section 4.6.3. of the KCSWDM
Peak rate runoff control will be provided through infiltration ponds in order to
mimic the existing natural drainage condition of the site, designed in accordance
with KCSWDM Section 4.5.2. Runoff resulting from areas subject to vehicular use
or storage of chemicals will be pretreated using water quality ponds as described in
Section 4.6 of the KCSWDM. See Section 4: Infiltration and Water Quality Sizing
Criteria and Results.
2.1.4 Core Requirement#4: Conveyance System
Requirement: All conveyance systems for proposed projects m ust be analyzed,
designed and constructed for existing tributary off-site runoff and developed on-site
runoff from the proposed project. .
See Section 5: Conveyance System Analysis and Design conveyance system design
criteria and calculations.
2.1.5 Core Requirement#5: Temporary Erosion and Sedimentation Control
Requirement: TESC measures shall be prouided that minimize the transport of
sediment to drain.age facilities, water resources, and adjacerct properti.es.
A Temporary Erosion and Sediment Control Plan has been prepared for this project,
and is included in the Design Drawings.
2.2 Special Requirements
2.2.1 Special Requirement#1: Critical Drainage Area
Threshold: Proposed project lies within a designated Critical Drainage Area as
indicated on Critical Drainage Area maps at the BALD Diuision Permit Center.
N/A. Project does not meet threshold criteria.
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2.2.2 Special Requirement#2: Compliance With an Existing Master
Drainage Plan
Threshold: Proposed project lies within an area covered by an approved Master
Drainage Plan as listed at the BALD Division Permit Center..
N/A. Project does not meet threshold criteria.
2.2.3 Special R,equirement#3: Conditions Requiring a Master Drainage
Plan
' Threshold: Proposed project is a Master Planned Development, a Planned Unit
Deuelopment, or will clear an area more than 500 acres within a contiguous drainage
subbasin.
N/A. Project does not meet threshold criteria.
2.2.4 Special Requirement#4: Adopted Basin or Coinmunity Plans
Threshold: Proposed project lies cvithin an area with an adopted Basin or
Community Plan as listed at the BALD Division Permit Center.
NIA. Project does not lie within an area with an adopted Basin or Community Plan
as listed at the BALD Division Permit Center
2.2.5 Special Requirement#5: Special Water Quality Controls
Threshold:Discharge area contains ►nore than 1 acre of new impervious surface that
r.uill be subject to vehicular use or storage of chemicals and (a)proposes direct
discharge of runoff to a regional facility, receiving wdter, lahe, wetland, or closed
depression without on-site peak rate runoff control; or (b)proposes discharge of runoff
through overland flow or on-site infiltration into d Class 1 or 2 stream, or Class 1
wetland, within one mile radius downstreanx from the project site.
N/A. Project proposes to discharge to on-site inf'iltration ponds that will provide
peak rate runoff control for 100-year, 24-hour and 100-year, 7-day storms.
2.2.6 Special Requirement#6: Coalescing Plate OiUWater Separators
Threshold: Proposed project will construct more than 5 acres of impervious surface in
any threshold discharge area that cvill be subject to (a)petroleum storage or transfer,
or (b) high uehicular use, or(c) heavy equipment use, storage or maintenance.
N/A. Site does not meet threshold criteria.
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2.2.7 Special Requirement#7: Closed Depressions
Threshold: Proposed project will discharge runoff to an existing closed depression
that has greater than 5,000 sf of water surface area at oz�erflocu eleuation.
N/A. Project does not meet threshold criteria.
2.2.8 Special Requirement#8: Use of Lakes, Wetlands or Closed �
Depressions for Peak Rate Runoff Control
Threshold: Project proposes to use a lake, wetland or closed depression for peak rate
runoff eontrol, to reeeiue a direct discharge, or to increase the uolume of runoff to an
off-site closed depression.
. N/A. Project does not meet threshold criteria.
2.2.9 Special Requirement#9: Delineation of 100-year FloodF�lai��
Threshold: Proposed project contains or abuts a stream, lake, wetland, or closecl
depression, or if other King County regulations require study of flood hazardti.
The project site does contain closed depressions, as there is no overland flow path i�
evidence within the proposed site area. However, the inf"iltration rates through
these soils and the depth of the water table suggests that there would be no standi�,
water on the site during a 100-year storm event. See Sectioil 22.1? f��r a de�ci-iption
of the Geotechnical Report findings for the project site.
2.2.10 Special Requirement#10: Flood Protection Facilities for Type 1 and
2 Streams
Threshold: Proposed project contains or abuts a Class 1 or 2 stream that has an
existing flood protection facility, or proposes to construct a new, or modify an existing,
flood protection facility.
N/A. Project does not meet threshold criteria.
2.2.11 Special R.equirement#11: Geotechnical Analysis and Report
Threshold: Proposed project will construct (1) a pond or infiltration system cuithin
200 feet from the top of a steep slope, or on a slope with a gradient steeper than 15%,
or using a berm higlxer than 6 feet, or(2) modifies an existing flood protection facility.
The proposed project will construct an infiltration pond approximately 130 feet from
the top of the steep slope south of the project area. This slope is inclined at
approximately 2H:1V. A Geotechnical Report was prepared for this site by HWA
GeoSciences, Inc., as is described in Section 2.2.12. In regards to the proximity of
the steep slope, the results of their analysis were summarized in a correspondence
from the geotechnical engineer as follows:
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Infiltrated water will seep down through the permeable recessional
outwash until it encounters the relatively impermeable glacial
tilUdrift, and will then seep in the direction of gravity along this
contact. Our borings indicate that the top of the Glacial TilUDrift,
below the proposed facilities, slopes down to the northwest as
illustrated in our Figure 6 [of the Geotechnical Report]. Thus, water
seepage from the easterly inf'iltration pond is not likely to flow toward
the south slope. It is our opinion, therefore, that storm water
infiltration at either infiltration pond location will not result in a
reduction of the stability of the south slope.
The location of the infiltration ponds is not anticipated to have any adverse impacts
on the steep slope.
2.2.12 Special Requirement#12: Soils Analysis and Report
Threshold: Soils underneath proposed project haue not been mapped, or the existing
soils rnaps are in error or not of sufficient resolution to allow the proper engineering
analysis of the proposed site to be performed.
A geotechnical report was prepared for this project by HWA GeoSciences, entitled
Geotechnical Report; Kin� Countv Re�ional Communications and Emergencv
Coordination Center; Renton, Washin�ton (June 20, 2001). This report is still in the
draft stage. j
The Geotechnical Report results indicate that the receptor soils in the areas of the
proposed ponds are unsaturated recessional outwash soils which exhibit "high
permeability," with a groundwater table at a depth of approximately 20 feet.
According to the field investigation included in Appendix A of the Geotechnical
Report, infiltration testing was performed with the following results:
HWA completed a single pilot infiltration test (PIT) in the proposed
easterly inf"iltration area in general accordance with Draft Ecology
guidelines (Ecology, 2000)...The relatively large-scale test was
conducted at a depth of approximately 6 feet below the ground surface,
or approximate elevation 327 feet. The test pit was excavated with a
bottom area of approximately 10 feet by 10 feet, and the sidewalls
were trimmed to about 1%H:1V. A 2-inch diameter fire hose with a
flow meter and butterfly valve were attached to a nearby hydrant
located in the City of Renton maintenance facility. The free end of the
hose was inserted into a 6-inch rigid pipe and splash bucket anchored
to the test pit bottom. A 6-inch pipe marked with 1-inch increments
was installed vertically in the bottom of the test pit to measure the
water level.
Water was added to the test pit at a ma�imuin flo« rate of about 12�
gallons per minute for 22'/z hours. The cunlulative volume and
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instantaneous flow rate were recorded every 30 minutes for the
duration of the test. Approximately 20,000 cubic feet of water flowed
into the pit over the 22%z hour test. There was no accumulation of
standing water in the pit throughout the entire test.
The results of this test indicate that the high permeability of the soil would preclude
saturated soil as an antecedent condition to a precipitation event, and that standing
water would not be an issue on the site.
2.2.13 Special Requirement#13: Aquifer Recharge and Protection Area
Threshold: Proposed project lies within an Aquifer Recharge and/or Protection Area
as defined and designed by City ordinance and as indicated on the Aquifer Recharge
and Protection Map at the City permit Counter.
Proposed project lies within Zone 2 of an Aquifer Protection Area as indicated on the
Aquifer Protection Map. Infiltration pond and water quality pond analyses, sizing,
and liners have been designed in accordance with the special requirements, methods
of analysis and design standards as outlined in the KCSWDM and the City of
Renton Municipal Code, as modified for inf'iltration within Zone 2 of an Aquifer •
Protection Area. See Section 4: Infiltration and VVater Quality Sizing Criteria and
Results.
07/17/01 8 Drainage Report
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Section 3 Offsite Analysis
3.1 Field Inspection
The site includes the King County Roads campus along with the area south of the
City of Renton Shops site. Also included are the steep slopes that drop down
towards the Maplewood area at the bottom of the valley. At the time that this report
was printed, the King County parcel was being subdivided. For the purpose of this
report, the site includes the full, roughly 100-acre parcel owned by King County.
Following subdivision, the subject project will occupy a lot of roughly 5 acres. Along
with the primary site, two off-site areas were visited, the Sunnydale Community,
entrance located at 375 Union Ave. SE and Leisure Estates located at 201 Union
Ave. SE.
The site was examined during a visit on January 5, 2001. The following surface
water features were observed:
There is an existing depression immediately north of the proposed easterly pond.
The depression is fed by an existing 12-inch corrugated metal flume about 70 feet
long that crosses diagonally over the Olympic Pipeline Company easement on the
east edge of the subject property. At the upstream end of the flume are two pipes,
one 18-inch diameter the other 12-inch diameter. These pipes appear to originate in
the RV storage lot that is shared by the mobile home parks. The flume was running
about one inch deep or less at the time of the site visit. Weather at the time was
intermittent rain.
Based on the City of Renton's stormwater map, number F5, the area tributary to the �I
closed depression is about 5 acres. It is probable that most of the rainfall originating
in the tributary area is intercepted by the storm drainage system in the Surinydale
Mobile home park. The Sunnydale system conveys the stormwater to a moderately
large detention pond that is a prominent feature on map number F5. It is
interesting to note that the outfall pipe downstream of this pond is slated for
replacement within the next year. The existing deteriorated CMP pipe will be
abandoned. A new on-grade HDPE pipe will convey flows from the pond down the
steep slope to the Cedar River Valley.
The other surface water feature observed was the ephemeral stream that parallels ,
the existing deteriorated pipe mentioned above. This stream was followed upstream �
to its source which proved to be a series of seeps emanating from the steep slopes
due south of the building site. The seeps were located about 20 or 30 vertical feet
down from the top of the slope. Approximately 3 or 4 were seen arrayed along the �I
head of the ravine, each at roughly the same elevation. Based on conversations with �
the geotechnical engineer, it is believed that the elevation of the seeps corresponds
with the top of the existing glacial till soil that is shown on Figure 7 in the ��
geotechnical report. When the seeps were again observed on March 14th of 2001, I��
they had nearly dried up.
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Section 4 Infiltration and Water Quality
Sizing Criteria and Results
4.1 Infiltration Ponds
Peak rate runoff control for the proposed project will be achieved through infiltration
ponds within the project site. Runoff from the project area will be directed to one of
three inf'iltration ponds. The contributing areas to these ponds are indicated in
Appendix A.
The infiltration ponds were sized according to the requirements of KCSWDM
Section 4.5.2, using the StormShed'" Stormwater Analysis software as developed by
Engenious Systems, Inc. StormShed utilizes the Santa Barbara Urban Hydrograph
(SBUH) method of runoff analysis.
The following table summarizes the contributing areas and hydrologic flow
characteristics for the developed site. Complete calculations have been included in
Appendix B.
Im ervious Area (ac) Pervious Peak Flow Rate Peak Volume
PGIS Non-PGIS Area (ac) (Qpeak, cfs) (Vpeak, ac-ft)
Western Pond 1.29 0.71 0.13 1.90 0.635
Eastern Pond 1.28 0.18 0.21 1.46 0.487
Central Pond - 0.23 - 0.23 0.070
Table 4-1
Hydrological Characteristics
100-year, 24-hour storm event
The infiltration ponds were preliminarily sized to inf'iltrate the 100-year 24-hour
storm and the 100-year 7-day storm, using infiltration only through the bottom area.
Rather than provide for an overflow conveyance system downstream from the ponds,
an additional factor of safety of two (2) is applied to the infiltration rate in the event
that the infiltration areas become plugged, effectively doubling the calculated size of
the ponds. The pond sizing is summarized in the following table. ',
Initial Peak Peak Outflow, Active Min. Bottom
Bottom Stage (ft) Infiltration Volume Dimension,
Area (ft2) (cfs) (ac-ft) ftxft)
Western Pond 1625 3.02 0.28 0.13 99 x 33
Eastern Pond 1200 3.03 0.21 0.14 85 x 28
Central Pond 300 0.97 0.05 0.01 60x10
Table 4.2
Infiltration Pond Characteristics
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4.2 Water Quality Ponds
The proposed project will result in an increase of pollution generating impervious
surfaces (PGIS) for the areas contributing to the western and eastern ponds. These
areas will be pretreated using water quality ponds, sized and designed according to
the KCSWDM Section 4.6. The ponds will act as water quality facilities to improve
the quality of the stormwater prior to the infiltration ponds. The ponds will be lined
in order to prevent inf'iltration of untreated surface water into the ground.
Water quality pond volumes are designed, at minimum, to contain the total vol��r„�
of runoff from the water quality design storm, having a total precipitation of on�
third of the 2-year, 24-hour design storm. The surface area of the pond is, at I
minimum, one percent of the impervious surface area in the drainage sub-basi�
contributing to the facility. Only that portion of impervious surface within the :aU-
basin that is pollution generating is routed through the water quality ponds.
The following table summarizes the design parameters for the water quality ponds.
Complete calculations have been included in Appendix C.
Contributing Peak Flow Peak Min. Surface Min. Surface
Area, PGIS Rate (cfs) Volume Area(a� 3' Dimension (ft x
ft2 ft3) de th (ft2 ft
Western 56,320 0.170 2182 727 15 x 49
Pond
Eastern 55,657 0.169 2164 721 15 x 48
Pond
Table 4.3
Water Quality Pond Characteristics
The Central Pond will not have a water quality pond prior to infiltration since none
of the contributing area is pollution generating.
4.3 Filter Strips
Runoff from the proposed roadway will be treated for water quality with a filter strip
along the western edge of the roadway. The width of the filter strip is a fraction of
the tributary area draining to the strip. For the 24-foot wide roadway proposed for
this project, the filter strip must be a minimum of 5.5 feet wide. See Appendix D for
filter strip sizing calculations.
07/17/O1 12 Drainage ReE�ort
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Section 5 Conveyance System
Analysis and Design
5.1 ConUeyance Design
They conveyance system was preliminarily sized using the Manning's equation,
assuming a minimum slope of 1%. The conveyance pipes are 12-inch diameter, and
are of adequate capacity to convey the 25-year 24-hour storm, as well as the 100-
year 24-hour storm without overtopping. See Appendix E for preliminary
conveyance sizing calculations.
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APPENDIX A
CONTRIBUTING AREA MAPS �I
RCR ECC Con��eyance Capacity Check Project No. Ol-Ol 1
?5-y7 �4-hr design storm
EASTERN POND CONVEYANCE CAPACITY CHECK
24HR Event Summary:
BasinlD Peak Q Peak T Peak Vol Area Method Raintype
Event ,
------- {cfs) __. (hrs) (ao-ft) ac /�oss
24HR 1.28 ; 8.00 0.4259 1.67 SBUHlSCS User1 25 yr
,-f -•
Drainage Area: 24HR
Hyd Method: SBUH Hyd Loss Method: SCS CN Number
Peak Factor: 484.00 SCS Abs: 0.20
Storm Dur: 24.00 hrs Intv: 10.00 min
Area CN TC
Pervious 0.2100 ac 85.00 0.17 hrs
Impervious 1.4600 ac 98.00 0.17 hrs �
Total 1.6700 ac
Supporting Data: '
Pervious CN Data: ,
On-Site Pervious 85.00 0.2100 ac
Impervious CN Data:
On-Site Impervious 98.00 1.4600 ac
Pervious TC Data:
Flow type: Description: Length: Slope: Coeff: Travel Time
Fixed On-Site Pervious 0.00 ft 0.00% 10.0000 10.00 min
Impervious TC Data:
Flow type: Description: Length: Slope: Coeff: Travel Time
Fixed On-Site Impervious 0.00 ft 0.00% 10.0000 10.00 min
� �
Conveyance Capacity.doc 2 of 2 07/13;01
KING COUNTY, W AS HINGTON, 5 UR FACE W ATER DES IGN 1vt ANUAL
FIGURE 3.S.1F 25-YEAR 24-HOUR ISOPLUVIALS .
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APPENDIX B
INFILTRATION POND CALCULATIONS
I .
RC&F.CC Infiltration Pond Project No. 01-01 1 �
Western Pond
CLEARHIS
RLPCOMPUTE [ROUTING] SUMMARY
100yr 7day MatchQ=PeakQ= 0.9748 cfs Peak Out Q: 02821 cfs - Peak Stg: 102.40 ft-Active Vol: 0.13 acft
100 yr MatchQ=PeakQ= 1.9005 cfs Peak Out Q: 0.2821 cfs - Peak Stg: 103.02 ft-Active Vol: 0.18 acft
Running P:12001101011\Civil\StormShed\ROUTING Report.pgm on Tuesday, July 10, 2001
Summary Report of all RLPooI Data I
Project Precips
[2 yrJ 2.10 in
[5 yr] 3.10 in
[10 yr) 3.65 in
(25 yr] 4.50 in i
[100 yr] 3.89 in
[100yr 7day] 9.75 in �
HYDLIST SUMMARY
[7DAY - 100yr 7day] [24HR- 100 yr] [7day Pondj [24hr PondJ
LSTEND
HydID Peak Q Peak T Peak Vol Cont Area
------- (cfs) (hrs) (ac-ft) (ac)
7DA-100yr 7day 0.97 55.00 1.6706 2.1300
24HR- 100 yr 1.90 8.00 0.6348 2.1300
7day Pond 0.28 50.33 1.6713 2.1300
24hr Pond 0.28 4.00 0.6348 2.1300
STORLIST
[PON D]
LSTEND
\�DA'I'ASVR�PROJECT�2001\01011\Civil\StormShed�PondWest.doc 1 of 2 07/10/Ol
RC&ECC Infiltration Pond Project No. 01-01 1
Western Pond
Node ID: POND
Desc: Infiltration Pond
Start EI: 100.0000 ft Max E1: 108.0000 ft
Contrib Basin: Contrib Hyd: �
Length ss1 ss2 Width ss3 ss4
65.0000 ft 3.00h:1 v 3.00h:1 v 25.0000 ft 3.00h:1 v 3.00h:1 v
Bottom area only with infiltration
DISCHLIST
[POND] �
LSTEND
Control Structure ID: POND - Infiltration control structure
Descrip: Infiltration Pond
Start EI Max EI Increment
100.0000 ft 108.0000 ft 0.10
Infil: 7.50 in/hr Multiplier: 1.00 �
\\DATASVR\PROJECT�2001\01011\Civil\StormShed�PondWest.doc 2 of 2 07/10/01
,
RCBECC Infiltration Pond 01-011
Western Pond
Contributing Area
Impervious Area
AP�,S = 1.29 acres
ARooF = 0.53 acres
AP�u= 0.18 acres
ATorn�iMa = 2.00 acres impervious
Pervious Area
AP�,= 0.13 acres pervious
TOTAL AREA A;,,,P= 2.00 acres
A��= 0.13 acres '
i
Design Storm
Per NOAA iso luvial ma s I�
100-year 24-hour storm: P= 3.89 in I
100- ear 7-da storm: P= 9.75 in '
Soil Type
Everett Material, T e B per Geotech email, 3/21/01
Infiltration Rate
I = 15 in/hr per Geotech Technical Memorandum, 1/17/01
I = 0.0003 ft/sec
Per KCSWDM pg 4.5.2-2, apply Factor of Safery of 2.0
I = 0.00017 ft/sec
Curve Number
Per KCSWDM Table 3.5.2B
CN perv= 85
CN im = 98
Time of Concentration (t�)
Assume 10 minute time of concentration.
P:12001/01011/Civil/OrainageWest.xls:90 KCSWO�A 1 of 1 7/10I01
`
RC&ECC Infiltration Pond Project No. O1-Ol 1
Eastern Pond ,
CLEARHIS I'�
RLPCOMPUTE [ROUTING] SUMMARY 'I
100 yr MatchQ=PeakQ= 1.4553 cfs Peak Out Q: 0.2083 cfs - Peak Stg: 103.03 ft-Active Vol: 0.14 acft
100yr 7day MatchQ=PeakQ= 0.7591 cfs Peak Out Q: 0.2083 cfs - Peak Stg: 102.49 ft-Active Vol: 0.11 acft
Running P:\2001\01011\Civil\StormShed\ROUTING Report.pgm on Monday, July 09, 2001
Summary Report of all RLPooi Data
Project Precips
[2 yr] 2.10 in
[5 yr) 3.10 in
[10 yr] 3.65 in '
[25 yr] 4.50 in
[100 yr] 3.89 in
[100yr 7day] 9.75 in
HYDLIST SUMMARY
[24HR - 100 yr] [7DAY- 100yr 7day] [24 hr outJ [7 day out�
LSTEND
HydID Peak Q Peak T Peak Vol Cont Area
------- (cfs) (hrs) (ac-ft) (ac)
24HR- 100 yr 1.46 8.00 0.4860 1.6700
7DAY-100yr 7day 0.76 55.00 1.2954 1.6700
24 hr out 0.21 4.17 0.4864 1.6700
7 day out 0.21 50.33 1.2954 1.6700
STORLIST
[POND]
LSTEND
P:�2001\01011\Civil\StormShed�PondEast.doc 1 of 2 07/09/O1
, �
RC&ECC Infiltration Pond Project No. 01-01 1 '
Eastern Pond
Node ID: POND
Desc: Infiltration Pond
Start Ei: 100.0000 ft Max EI: 104.0000 ft
Contrib Basin: Contrib Hyd:
Length ss1 ss2 Width ss3 ss4
60.0000 ft 3.00h:1 v 3.00h:1 v 20.0000 ft 3.00h:1 v 3.00h:1 v
Bottom area only with infiltration
DISCHLIST
[POND] ;
LSTEND �
Control Structure ID: POND - Infiltration control structure I
Descrip: Infiltration Pond
Start EI Max EI Increment
100.0000 ft 104.0000 ft 0.10
Infil: 7.50 in/hr Multiplier: 1.00
1':\2001\0101 1\Civil\StormShed�PondEast.doc 2 of 2 07/09/01
RC&ECC Infiltration Pond 01-011
Eastern Pond
Contributing Area
Impervious Area
�c�s = 1.28 acres
�aooF = 0.18 acres
Arorn�iMP = 1.46 acres impervious
Pervious Area
AuwoscnPwc= 0.21 acres pervious
TOTAL AREA A;mp= 1.46 acres
A�,= 0.21 acres
Design Storm
Per NOAA iso luvial ma s
100-year 24-hour storm: P= 3.89 in
100- ear 7-da storm: P = 9.75 in
Soil Type
Everett Material, T e B per Geotech email, 3/21101
Infiltration Rate
1 = 15 in/hr per Geotech Technical Memorandum, 1/17/01
I = 0.0003 ft/sec
Per KCSWDM pg 4.5.2-2, apply Factor of Safety of 2.0
I = 0.00017 ft/sec
Curve Number
Per KCSWDM Table 3.5.2B
CN perv= 85
CN im = 98
Time of Concentration (t�)
Assume 10 minute time of concentration
PJ2001?01011/Civil/DrainageEast.xls: 9G KCS'.�'JD��1 1 of ', 7I1G/01
RC&ECC Infiltration Pond Project No. 01-011
Central Pond
CLEARHIS
RLPCOMPUTE [ROUTING] SUMMARY
100yr 7day MatchQ=PeakQ= 0.1060 cfs Peak Out Q: 0.0521 cfs - Peak Stg: 100.70 ft -Active Vol: 273.06 cf
100 yr MatchQ=PeakQ= 0.2343 cfs Peak Out Q: 0.0521 cfs - Peak Stg: 100.97 ft -Active Vol: 417.53 cf
Running P:12001101011\Civil\StormShed\ROUTING Report.pgm on Wednesday, July 11, 2001
Summary Report of ail RLPooI Data
Project Precips
(2 yr] 2.10 in
[5 yr] 3.10 in
[10 yr] 3.65 in
[25 yr] 4.50 in
[100 yr] 3.89 in
[100yr 7day] 9.75 in
HYDLIST SUMMARY
[7DAY- 100yr 7day] [24HR- 100 yr] [7DAY- 100yr 7day] [24HR - 100 yr] [7day Pond] [24hr Pond]
LSTEND
HydID Peak Q Peak T Peak Vol Cont Area
' ------- (cfs) (hrs) (ac-ft) (ac)
7DAY- 100yr 7day 0.11 55.00 0.1823 0.2300
24HR- 100 yr 0.23 7.83 0.0701 0.2300
7day Pond 0.05 52.50 0.1822 0.2300
24hr Pond 0.05 6.83 0.0701 0.2300
STORLIST
[POND]
LSTEND
\\DA"fnSVRU'ROJECT�2001\01011\Civil\StormShed�PondCentral.doc 1 of2 07/11/Ol
RC&ECC Infiltration Pond Project No. 01-011
Central Pond
Node ID: POND
Desc: Infiltration Pond
Start EI: 100.0000 ft Max EI: 108.0000 ft
Contrib Basin: Contrib Hyd:
Length ss1 ss2 Width ss3 ss4
30.0000 ft 3.00h:1 v 3.00h:1 v 10.0000 ft 3.00h:1 v 3.00h:1 v
Bottom area only with infiltration
DISCHLIST
[POND]
LSTEND
Control Structure ID: POND - Infiltration control structure
Descrip: Infiltration Pond
Start EI Max EI Increment •
100.0000 ft 108.0000 ft 0.10
Infil: 7.50 in/hr Multiplier: 1.00
\\DA1'ASVR�f'ROJECT�200 110 1 0 1 1\Civil\StormShed�PondCentral.doc 2 of 2 07/1 1/O1
RCBECC Infiltration Pond p�_p��
Central Pond
Contributing Area
Impervious Area
ARooF = 0.23 acres
Arorn��MP = 0.23 acres impervious
TOTAL.AREA A;mp= 0.23 acres
Design Storm
Per NOAA iso luviai ma s
100-year 24-hour storm: P= 3.89 in
100- ear 7-da storm: P=9.75 in
Soil Type
Everett Material, T e B per Geotech email, 3/21/01
infiltration Rate
I = 15 in/hr per Geotech Technical Memorandum, 1/17/01
I = 0.0003 ft/sec
Per KCSWDM pg 4.5.2-2, appiy Factor of Safety of 2.0
I = 0.00017 ft/sec
Curve Number
Per KCSWDM Table 3.5.26
CN im = 98
Time of Concentration (t�}
Assume 10 minute time of concentration
PJ2GC�;C�'�',1,Ci��,�J!DrainaaeCentral x's: 9��;�(CS'v"vC^.1 1 of 1 '�1G�01
\
KING COUhTY. W ASHfNGTON. SURFACE WATER DESIGN M .ANU ,q �
FIGURE 3.S.1C 2-YEAR 24-HOUR [SOPLU�`IALS
- - - _ � - "`- �'�� ;�-�, � , _ =S� = r =
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2-YEAR 24-HOUR PRECIPITATION 1
f� '- e ��.+ '
,. 3.4 �" ISOP�UVIALS OF 2-YEAR 24-HOUR �' � � - - � • -- - _ 35
TOTAL PRECIPITATION IN INCHES "� � ' , � ,
----- - � ry A.�� . ;, - ' �
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cy ni �7`� ,, . � -
ry � _ � - - \�
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K 1 N G C O U N T 1". �4� A S ii I ."J G T O N, S U R F A C E W A T F R D E 5 i G N P•t A i� U A L
FICURE 3.S.1H 100-YEAR 24-HOUR ISO('LUVIALS
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100—YEAR 24—HOUR PRECIPITATION � � • ' � 6�
- 3.4 ISOPLUVIALS OF 100-YEAR 24HOUR ! � p�� � \ � � ;, $,5
TOTAL PRECIPITATION IN INCHES 0�� � �" � _ ,
-- ---- — � �`� � � �� , \ :" /s..1
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K [ ` G C O U N T Y. �4' ,� S H I h' G T O N. S U R F A C E ��' .� T E h D E S [ G ti' f�1 A N l� A L
-- --- -- - _--
I�IGURE3.�.1[ 100-YEAR 7-DAY ISO['LUVIALS
82 1_�. ;r� .�y � �_�, �� ' , �'`
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,� �' �. , `�tL� , �
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---- --- - �p• �.. , - -- .� �. •~� L �,- ` - '�� .
; 100–YEAR 7–DAY PRECIPITATION I � —� � ' ' � �
� -� 3.4 =ISOPLUVIALS OF 10aYEAR 7-DAY , ,�Q� , ,�E . - 1 ` �J�,�
TOTAL PRECIPITATION IN INCHES .`0���_�;. ' �__i .,. ��\__ -: ' r3.O
� __-- _ - -- O' �o � ' - -
0 1 2 3 4 5 6 7 8 Mlles � �� (b - ' � ' '`
. � ` t "
i: 300.000 3.�.1-l�l � � O '. - _ `- _ \ ...J, ,
�1i _ � �-
• +� � I/9f)
� K i N G C O U N T Y, �1' ,A S H I V G l� O N, S U R f= A C E ��' A T E R D E S f G ti �1 A �ti U :� l_
TABLF: 3.S.Z[3 SCS �VESTERN \VASIfINGTON RUNOFf� CURVE NUTt9QERS
SCS WESTERN WASHINGTON RUNOFF CURVE NUMBERS (Published by SCS in 1982) I�I
RunoH curve numbers tor selected agricultural, suburban and urban land use lor Type �A
rain(all distribution, 24-hour storm duration.
CURVE NUMBERS BY I'i
HYDROLOGIC SOIL GROUP
LANO USE DESCRIPTION A B C D
Cultivated land(t): winter condaion 86 91 9a 95
Mountain open areas: low growing brush and grasslands 74 82 89 92
Meadow or pasture: 65 78 85 89
Wood or forest land: undisturbed or older second growth a2 6a 76 gt �
Wood or torest land: young second growth or brush 55 72 8t 86
Orchard: with cover crop 8� 88 92 94
� il
Open spaces, lawns, parks, gol( courses, cemeteries. �
landscaping.
good condition: grass cover on 75%
or more of the area 68 80 86 90
fair cond4ion: grass cover on 50°�6
to 75°� of the area 77 85 90 92 I
Gravel roads and parking lots 76 SS 89 91
Dirt roads and parking lots 72 82 87 89
Impervious suriaces, pavement, roots, etc. 98 9 98 98
Open water bodies: lakes, wetlands, ponds, etc. �00 00 t00 �00
Single Family Residential (2)
Dwel�ing Unit/Gross Acre °,6 Impervious (3)
1.0 DU/GA t 5 Separate curve number
1.5 DU/GA 20 shall be selected
2.0 DU/GA 25 for peniious and
2.5 OU/GA 30 impervious portion
3.0 OU/GA 3a of the site or basin
3.5 OU/GA 38
a.o ou/ca a2
a.5 DU/GA a6
S.0 OU/GA 48 -
5.5 DU/GA 50
6.0 DU/GA 52
6.5 DU/GA 54
7.0 DU/GA 56 e�--
Planned unit developments. �6 impervious
condominiums, apartments, must be computed
commercial business and
industrial areas.
(1) For a more detailed description of agr�cultural land use curve numbers refer to National Engineering
Handbook, Section 4, Hydrology. Chapter 9, August 1972.
(2) Assumes rool and driveway runoH is directed into street/storm system.
(3) The remaining pervious areas (lawn) are considered to be in good condition for these curve numbers.
�n 3.�.2-3 11/92
�J'
APPENDIX C
WATER QUALITY POND CALCULATIONS
I
RC�ECC Infiltration Pond Project �Io. Ol-Ci11
��'et Ponds
CLEARH IS I
East Event Summary:
BasinlD Peak Q Peak T Peak Vol Area Method Raintype
Event
------- (cfs) (hrs) (ac-ft) ac /Loss
East 0.17 7.83 0.0497 1.28 SBUH/SCS User1 WQ
Drainage Area: East
Hyd Method: SBUH Hyd Loss Method: SCS CN Number
Peak Factor: 484.00 SCS Abs: 0.20
Storm Dur: 24.00 hrs Intv: 10.00 min
Area CN TC
Pervious 0.0000 ac 78.00 0.00 hrs
Impervious 1.2800 ac 98.00 0.08 hrs
Total 1.2800 ac
Supporting Data:
Impervious CN Data:
PGIS 98.00 1.2800 ac
Impervious TC Data: �
Flow type: Description: Length: Slope: Coeff: Travel Time
Fixed PGIS 0.00 ft 0.00% 5.0000 5.00 min
West Event Summary:
BasinlD Peak Q Peak T Peak Vol Area Method Raintype
Event
------- (cfs) (hrs) (ac-ft) ac /Loss
West 0.17 7.83 0.0501 1.29 SBUH/SCS User1 WQ
Drainage Area: West
Hyd Method: SBUH Hyd Loss Method: SCS CN Number
Peak Factor: 484.00 SCS Abs: 0.20
Storm Dur: 24.00 hrs Intv: 10.00 min
Area CN TC
Pervious 0.0000 ac 78.00 0.00 hrs
Impervious 1.2900 ac 98.00 0.08 hrs
Total 1.2900 ac
Supporting Data:
Impervious CN Data:
PGIS 98.00 1.2900 ac
Impervious TC Data:
Flow type: Description: Length: Slope: Coeff: Travel Time
Fixed PGIS 0.00 ft 0.00% 5.0000 5.00 min
�VetPond.doc l oC 1 O;i 10i01
S ��� � � � .00 t �econd :���e- � �uite 100�� Sza«le. A��.� 9�?l�J l-l�+l
�Q� � - P- ?Ob/+41-18» � F: 206;-+-+�t-;16i
�. ,�ct ��/ C� �.��.— loh�';t � i _ , � Itn;� . ,a
X�
❑icr,t —_— — E� � :1,..,�_ Dw: ..Q �;
Suhirn � G.<tl:c:t I-��n.
wc�l-t/ (�,�c�.� =�.�'��,�J •
���,�,c,� ��-L c� = � �' d�- i G{� p 1� G`'��,�.��o� �rlc,
�5T - i�(,1; : � ;; , ; � �� � x ( r�, d� ) = 56 � �
�bT � ��'� � - �5 � �� �� x ��. �'� ) = S� � �
� , .
�f ol��-e =
� u.�INU F�:,�t,�J ��� )
A-�,�,� - i . I �� � .
CN = 9 �
TL = � M�, Cc�.,�C.v�c:.��l
�c,�(� � '! 3 ( Fz � ' ��7 C � ' � ` � _ �j i � ..
^- -- � 2 � ��.
r G�,--
K I N G C O U N T 1", W .A S H ( N G T O N. S U R F A C E W A T E R D E S [ G N �ti1 A N U A L
FIGURE 3.S.1C 2-YEAR 2�-HOUR [SOPLUVIALS
- - - r Q� ` , _�
� �
- __ - . ��f-_ � � }� � % _.-'r- _. _ - - - -s - - - -
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- ; _ ��� � � -�.�� '` . l _ ' -
� ° — - �. '-��� �-- i - � _. `
� ', L ` +�� � R«„� � j . �� j �- � `
' \ ' � - , �--1 � —. '�' `
� / �J � E4:� - `,`\ .-c ��
I_1 � �� � �� -�, `
�� i ` ` � � � ' � - .-� f � � f
�-�__ ,__ � J r j > `' ` `� - _ �
ry _ _�y �-y __ _ ��. - .... _ y. � � �...
�� ', J � 9 i __� � ___ �� " G _ t
�� . � � �� � ��a� \�' - �.' . �
� \±. — ���I �\ /�. � ..1��� `�
f -� Lf ' /�� �
�' l ;�� _� ;,;,�- �``" . _ �
Q� `�` �� •� r r - � yh �i
_ � � �
� � �
2—YEAR 24—HOUR PRECIPITATION � ' � �<� �
r 3.4 �" ISOPLUVIALS OF 2-YEAR 24-HOUR ; �+' '. � __ __ _ '� 35
TOTAL PRECIPITATION IN INCHES �•� �*�L `� I - _ "
- — �1+ . ` \ y
�"' `
0 1 2 3 a 5 6 7 8 /v�I i es "
�i N 4?'�c•�. _ � ��
�: 3a�.0�0 � �'_ ---` ���;�'�` .
3.S.1-S � U°0
APPENDIX D
FILTER STRIP CALCULATIONS
� � � I �� � � � IhUI ��concl .���c �uuc 10�0 � Seattle, �VA 98101-1�-}1 �
= f' 'Obi:-�t-l3» F: ?06l-F�+8-;l67
( r � � ' � � Pa i f ol j �I
Prr�a��i �;��_d' C i.�L fn��'o � � K� .
Chrni B� �.J.��r: Darr % ' � ,�� � '
Subjt�t �L,T�it �''.Y_ ' /� �' r^ ^_�r Chrdird Duti
�e✓. 1��w�M � � ����„ y, �, y , p5 . y. �. y - �
�� l�� S-�,�,�� s��=� .
,
w = � �- ��N,��� �,� > �°� , �' � � ( 2 `1 �- ) �Q Z,) = S� S? n
� �J -
APPENDIX E
CONVEYANCE SYSTEM CALCULATIONS
� � ��� � � � � Il�lll Si�uit�l ,\�r �uitc I011�l tie;tlllc. �VrA �)tii01-I�+I
I' )061�-11-1�» 1 � �0(i;��ti-716�
�,,��,:, �ZC � c�C, �,d,,v�, p� - J I I �'�c� 1 , �
--- - ------ - --- — --- �7 -/ _ _
Clirn( f3c r../ / .�Sl.l_. D:ur '7 r �?l p �
liClJ�
�r� ��� � -------- ------------
— ._ _.__-------
Subli�( (/`ir,/l/��'h/(� C'i' �1✓�T`� �� C.h�tl:i�l U<i��� _._____
�, ��yi,FL�^�1'U�s�'1'J ,f��1^/(r� M/t��N�P-�lr I �?N
ZS - Y� ZY -�ln- �-�-^�� � P�-e�z,. P = �. `1 S ,:.
�t� �n�� �'Yt1 � �•✓'s ¢ ?� 'S ��-''� fiv��v�1�tS�''�1 Cstt,e J
�;�r�_��
f},,,,� = 2 0 ,�-z
��r,� " �� 1� �-•
C�✓ Pt�� ` £'S
CrJ �/..,� " �}L�
�4 � �O M 1/1 '
ri���� l���� .
�„�P = �.y� ��
Art� = o, � � kr_
C^� �,,,,P ' ��
��/ p,�� � �;
�L — � � � ��
�.(� S'S�'�.�-- (f��'('c^':i I'
�
a����.K, '� � �- �
�cli�� u ' 1 z� �-h
Fj f� S��t,('�
Qwc� (�0 = � , � =� c�.
Q�u;1_ �„D � � . `(� �%S
Q ! ' n V
�,��Y 3 g c�� � <.�U��� r�_ .��. , �,�,�:_¢�� �
� u
�-�� �,, � r l �:�! nf`'•L�'-'� �c �G ��`�_ CC-.�
KING COUNTY, ��' ASH l �JGTON, SURFACE �4' ATER D ESIGN �t .-� �' l! .� L
[�ICURE 4.3.4A NO�'tOGRA['H f�OR S[ZING C[RCULAR DRAINS FLO�VING FULL �
1000
90Q ,
800 000t
700 2_0
6� .0002
500 Minimum
.0003 Allowable
a00 -a�� .00Ot Velocity
.000s (Flowing� 3.0
300 Fuif)
�20 � .0008�.0002
108 a .001 � .00a3
0
200 gg ,i .0004
90 c .002 .0005 4�p
84 � .0006
�$ p .003 .0008 U u,�/7''�
.Q� .�Q� �/^nh i 1� �/ 1'5,��
66 w 005 / 5.0
lOO 60 O .006 N �
90 � � .008 � .002 � O
80 4 8 .O 1 � w 6.0
7G � .003 �
w 42 � c �
� 60 U a2 .0�05 � w 7.0
ti Z 36 .00 � �
50
U 33 .03 . OS � w 8.0
Z w
Z 40 w 30 .p4 10 O LL,
w a 27 .0 � � 9.0
� a —
�
Q 30 LL 24 .08 .020 >- �0.0
_ � 21 .10 ~
¢ .030 U
� "' 18 �
0 Z� ~ -�� J
� .050 j
Q 15 .060
p .080
�
�Z .100
.
10 10
9 � SAMPLE USE
8
� 1�( 8 24" dia. CMP @ 2�o slope yieids zo.o
6 17cfs @ 5.2 FPS velocity
(n = 0.024}
5 g
4 Values pe� Manning's Equation
t� ' Q = ( 1.49� AR=/�S'/z
/�'✓1C O
3 � 30.0
3' � This tabie can be convened
�� to other"n"values b a I in
Y PP Y 9
2 formula:
a0.0
Q1 nt
Q2 n2
i
4.3.�-18 l l�)0
� RCB:ECC Conveyance Capacit�� Che�k Project tio. O1-0l 1
25-yr 24-hr design storm
WESTERN POND CONVEYANCE CAPACITY CHECK
24HR Event Summary:
BasinlD Peak Q Peak T Peak Vol Area Method Raintype
Event
------- �{cfs��. (hrs) (ao-ft} ac /Loss "
24HR 1.67 8.00 0.5574 2.13 SBUH/SCS User1 25 yr
`�.
��_,,
Drainage Area: 24HR
Hyd Method: SBUH Hyd Loss Method: SCS CN Number
Peak Factor: 484.00 SCS Abs: 0.20
Storm Dur: 24.00 hrs Intv: 10.00 min
Area CN TC
Pervious 0.1300 ac 85.00 0.17 hrs
impervious 2.0000 ac 98.00 0.17 hrs
Total 2.1300 ac
Supporting Data:
Pervious CN Data:
On-Site Pervious 85.00 0.1300 ac
Impervious CN Data:
On-Site impervious 98.00 2.0000 ac
Pervious TC Data:
Flow type: Description: Length: Slope: Coeff: Travel Time
Fixed On-Site Pervious 0.00 ft 0.00% � 10.0000 10.00 min
Impervious TC Data:
Flow type: Description: Length: Slope: Coeff: Travel Time
Fixed On-Site Impervious 0.00 ft 0.00% 10.0000 10.00 min
l:onvcyailce C�pacit;� �u� 1 ut�-' U�,, l�,{J I
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