HomeMy WebLinkAboutStormwater Plan and Geo Review - PLN General - 7/13/2005 STATEO�
S N O 2
0 S T z MASON COUNTY
rZ N Y o PUBLIC WORKS DIRECTOR/COUNTY ROAD ENGINEER
0 Shelton,Washington 98584
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DATE: July 131h, 2005
INTER-DEPARTMENTAL COMMUNICATIONS
TO: Tammi Clark, DCD—Planner
FROM: Alan A. Tahja, P/W - Co. Hydr. Engr.
SUBJ: Stormwater Plan& Geo Rvw NAME: Straatman—Lilliwaup Post Office .
COM2005-00072 & COM2005-00073
Tammi,
The Geotechnical assessment and the Stormwater and erosion/sediment Control plan
prepared for the Lilliwaup Post Office located at Lilliwaup has been received and
reviewed by Public Works.
The report appears to satisfactorily fulfill County requirement(s). Requirements
contained in the Geotechnical Report by Bradley Noble Geotechnical Services should
be adhered to and incorporated into the site's development and made as part of the
conditions for permit issuance. The Stormwater Control Plan and the Erosion and
Sediment Control Plan prepared for the Lilliwaup Post Office appears acceptable and
should also be made a requirement for the permit issuance. I recommend accepting the
report as satisfying the County's requirement(s).
Adequate Erosion and Sediment (E&S) control features need to be implemented during
land disturbing activities to protect neighboring properties and State waters from
adverse stormwater runoff impacts. The migration or release of silty water or mud from
the applicant's property will be considered a violation of County and State water quality
protection regulations.
Please feel free to contact me at County extension 461 if you have any questions
regarding these comments, or if you feel any features need further discussion or
attention.
Sincerely,
Alan A. Tahja
File: H:\WP\Strmwtr\Reviews\XXXxxXX.doc
MASON COUNTY
PUBLIC WORKS DIRECTOR/COUNTY ROAD ENGINEER
Shelton Washington 98584
DATE: Oct. 24 h, 2000
INTER-DEPARTMENTAL COMMUNICATIONS
TO: Jason Manassee,DCD—Planner
FROM: Alan A. Tahja, P/W-Co. Hydr. Engr.
SUBJ: Stormwater Site Plan Review NAME: Ouellette—Lilliwaup Post Office
A Stormwater Site Plan(SSP)prepared for the proposed Lilliwaup Post Office has been received
and reviewed by Public Works.
The plan conforms to standards of good engineering practices and principles for this time and
place, and appears to meet present standards for stormwater quality and quantity control.
I've been in contact with the project engineer,Lorna Taylor, and requested that they provide a
letter of concurrence or authorization to site their proposed bio-swale in the State Highway's
right-of-way. Authorization from the State to construct the swale in the right-of-way complicates
who is to maintain the swale,but I expect Ouellette and WSDOT to be able to work something
out.
Akin to the right-of-way issue is completion of the Operation and Maintenance Covenant, its
recording, and delivery of a copy of the recorded document to Public Works for monitoring and
administration.
The right-of-way issue and O&M Covenant are the only details I see that still need addressing,
otherwise the SSP can be considered complete.
Please feel free to contact me at County extension 461 if you have any questions regarding this
department's review or these comments. I will keep you informed of any materials I receive
pertaining to the two remaining issues.
Sincerely,
Alan A. Tahja
File: H:\WP\STRMWTR\REVIEWS\LilliWP-PO.doc
STORMWATER AND EROSION/SEDIMENT
CONTROL SITE PLAN
for
Lilliwaup, Washington Post Office
Site Location:
28611 North US Highway 101
Section 30, T23 N, R3W, W.M., Lilliwaup, Mason County, WA
Prepared for
Owner:
John Straatman
P.O. Box 68
Lilliwaup, WA 98555
Phone: (360) 877-5188
Architect:
Foster and Williams Associates, P.S. AIA Architects
P.O. Box 102 — 601 W.Railroad Ave., Suite 100
Shelton, WA 98584
Contact: Len Williams
Phone: (360) 426-0511
Fax: (360) 426-2926
e-mail: fw@hctc.com
Prepared by:
MARLEY L. YOUNG, CONSULTING ENGINEER
P.O. Box 1343
Shelton,WA 98584
Phone: (360) 426-7475
Fax: (360)426-5789
e-mail: myoung3542@aol.com
Project No. 2005-22
May 18,2005
MARLEY L. YOUNG, CONSULTING ENGINEER
Civil Engineering P.O. BOX 1343, SHELTON, WA 98584-0959
Storrrwvater Site Plans
(360)426-7475 FAX (360) 426-5789
Sewer Extensions Marley L. Young, P.E., P.L.S.
o Civil Engineer& Land Surveyor
o
PROJECT ENGINEER'S CERTIFICATION
I hereby certify that this Stormwater and Erosion/Sediment Control Site Plan prepared for
the Lilliwaup, Washington Post Office, has been prepared by me or under my supervision
and meets minimum standards of Mason County and normal standards of engineering
practice. I understand that the jurisdiction does not and will not assume liability for the
sufficiency, suitability, or performance of drainage facilities designed by me.
Marley L. Young, P.E., P.L.S.
h
b
141IST
44
NA
DORES 3/5/04
Marley L.Young,Consulting Engineer
Project No.2005-22
J
1
Lilliwaup Post Office
TABLE OF CONTENTS
Page
Engineer's Certification
Table of Contents
Best Management Practices(BMPs) .............................................................. 1
Large Parcel Stormwater Site Plan
I. Project Overview .............................................................. 2
Minimum Requirements#2-#11 .............................................................. 2
II. Plot Plan .............................................................. 4
III. Preliminary Conditions Summary .............................................................. 4
IV. Off-site Analysis .............................................................. 4
V. Permanent Stormwater Quality Control Plan ....................................................... 4
Storm Event Design Assumptions .............................................................. 4
VI. Special Reports and Studies(Not Applicable to this Plan) ...................................... 5
VII. Basin and Community Planning(NA) .............................................................. 5
VIII. Permits .............................................................. 5
IX. Erosion and Sediment Control Plan .............................................................. 5
Minimum Requirements#1415 .............................................................. 6
.................
X. Bond Quantity Worksheets(NA),Detention Facility Summary Sheet and Sketch(NA),
Declaration of Covenant ..............................................................
XI. Operation and Maintenance Manual .............................................................. 8
Changed Conditions .............................................................. 9
..................
*************************************************************************************
ATTACHMENTS
SUPPORTING CALCULATIONS
Marley L.Young,Consulting Engineer
Project No.2005-22
i
STORMWATER AND EROSION/SEDIMENT CONTROL SITE PLAN
for
LILLIWAUP,WASHINGTON POST OFFICE
The Puget Sound Water Quality Management Plan(PSWQMP),which is administered by the State of
Washington Department of Ecology,mandates that all counties and cities within the Puget Sound
drainage basin adopt ordinances to control runoff from new development and redevelopments. The
PSWQMP also directs local governments to adopt stormwater programs that must include minimum
requirements that are consistent with the PSWQMP,and which are substantially equivalent to the DOE's
Stormwater Management Manual for the Puget Sound Basin,(DOE's Technical Manual).
The goal of the Puget Sound Water Quality Management Plan is to:
■ Protect and restore beneficial uses of aquatic resources,including shellfish beds,fish habitat,and
other resources;
■ Prevent contamination of sediments from urban runoff;
■ Meet standards for water and sediment quality by reducing pollutant discharges from stormwater
throughout Puget Sound.
BEST MANAGEMENT PRACTICES(BMPs)
Best management practices(BMPs)are defined as physical,structural,or management practices that,
when used singly or in combination,prevent or reduce pollution of water. Specific BMPs have been
developed by Ecology to control stormwater runoff(quality and quantity)for protection of receiving
waters.
There are three main reasons for applying BMPs before considering advanced treatment.
First, it has been shown through research and experience that BMPs can significantly reduce pollutants in
stormwater. Using BMPs to control localized discharges is cost effective in comparison to treating large
volumes of water.
Second,our lakes and streams depend on stormwater to provide adequate flow for fish habitat and water
quality. Our groundwater resources also depend on stormwater for recharge. BMP implementation offers
a way to discharge water back into the natural system.
Third,and perhaps most important, stormwater management programs demand the conscientious use of
best management practices to protect water quality.
Specific BMPs that cover stormwater runoff quality and quantity have been included in Ecology's
Technical Manual. Those BMPs can be divided into three basic categories,including Source Control
BMPs,Runoff Treatment BMPs and Streambank Erosion Control BMPs.
Source Control BMPs are designed to prevent pollutants from entering stormwater by eliminating the
source of pollution or by preventing contact of pollutants with rainfall and runoff. Source controls are
usually the most cost-effective because they reduce or eliminate the need for treatment BMPs.
Implementing source control BMPs generally involves relatively simple and straightforward actions.
Examples of source control BMPs include erosion control(e.g.,covering disturbed soil),covering
material storage areas, and eliminating illicit discharges.
Marley L.Young,Consulting Engineer
Project No.2005-22
Lilliwaup Post Office site
Runoff Treatment BMPs are designed to remove pollutants contained in stormwater runoff. These
types of BMPs are the second line of defense in protecting stormwater quality. Examples of runoff
treatment BMPs include infiltrated basins bioswales and sedimen
t ponds.
Streambank Erosion Control BMPs are designed to protect stream ecosystems from erosion and
sedimentation. Types of streambank erosion control BMPs include flow attenuation BMPs for reducing
peak flows from a development(e.g., detention ponds, infiltration trenches),and streamside stabilization
BMPs used to stabilize eroding streambanks.
I. PROJECT OVERVIEW
PROPOSED PROJECT DESCRIPTION:
Construction of a new Post Office in Lilliwaup,Washington, including parking and landscaping,etc.
Lilliwaup has had a Post Office for many years. The proposed new facility will replace the existing Post
Office;therefore,the proposal is considered a redevelopment.
LEGAL DESCRIPTION
The site is located in Section 30,Township 23 North,Range 3 West,W.M.,Lilliwaup,Mason County,
Washington.
Mason County Auditor's Parcel No. 32330-51-56013
EXISTING CONDITIONS:
The new facility will occupy 0.82 acres of property east of the existing Lilliwaup Store and Motel, all
located on the landward side of US Highway 101.
GENERAL LOCATION:
The site address is 28611 North US Highway 101,Lilliwaup,Washington.
STORMWATER AND EROSION/SEDIlVIENT CONTROL PLAN REQUIREMENT
DETERMINATION:
Projects that add 5,000 square feet or more of new impervious surface must comply with the Large Parcel
Minimum Requirements.
A Large Parcel Erosion and Sediment Control Plan is discussed,and the necessary BMPs are included in
this report. The report will review the components of the Large Parcel Stormwater Site Plan,which
include the temporary erosion and sediment control necessary during construction,permanent stormwater
quantity control,civil drawings and specifications,and operation and maintenance recommendations for
the needed stormwater facilities.
This project will comply with the following Large Parcel minimum Requirements#2 through#11 found
in Section I-2.5 through 1-2.15 of the Department of Ecology' Stormwater Management Manual for the
Puget Sound Basin(the Technical manual).
Minimum Requirement#2: PRESERVATION OF NATURAL DRAINAGE SYSTEMS
Natural drainage patterns shall be maintained,and discharges from the site shall occur at the natural
location,to the maximum extent practicable.
No surface water drainage flows through this project.
Minimum Requirement#3: SOURCE CONTROL OF POLLUTION
Soil erosion and gravel migration are not expected to become an issue. Soils are classified as Grove
(Gk), SCS Soil Group A.
2 Marley L.Young,Consulting Engineer
Project No.2005-22
f
Lilliwaup Post Office site
Where necessary to prevent the migration of silt during construction, the owner/contractor shall
construct channels to keep overland flows away from the area under construction. If dust becomes a
problem, dust control methods using water shall be employed.. If necessary to reduce tracking of mud
and debris onto paved roads, the owner/contractor shall utilize a construction entrance rockpad. If
required, migration-sensitive soils shall be covered with straw mulch or blackplastic to prevent off-site
migration of soil.
The erosion control plan consists of installing a construction entrance, hay bales, and a sediment
trap, when deemed necessary.
Minimum Requirement#4: RUNOFF TREATMENT BMPS
Grass swale will be used as the method of treatment.
Minimum Requirement#5: STREAMBANK EROSION CONTROL
Total infiltration is on site, and infiltration rates will meet or exceed STREAMBANK EROSION
CONTROL requirements.
Minimum Requirement#6: WETLANDS
NA—The site does not include wetlands.
Minimum Requirement#7: WATER QUALITY SENSITIVE AREAS
NA
Minimum Requirement#8: OFF-SITE ANALYSIS AND MITIGATION
NA—Total infiltration onsite;therefore, offsite analysis is not required.
Minimum Requirement#9: BASIN PLANNING
An adopted and implemented basin plan may be used to develop requirements for water quality sensitive
areas that are tailored to a specific basin.
NA—No basin plan has been established at this location.
Minimum Requirement#10: OPERATION AND MAINTENANCE
An operation and maintenance schedule shall be required for all proposed stormwater facilities and BMPs,
and the party(or parties)responsible for maintenance shall be identified.
The owner is responsible for operation and maintenance of the stormwater facilities. To ensure that the
proposed stormwater control facilities are adequately operated and maintained, an Operation
and Maintenance (O&Af) Covenant will be required. A "Declaration of Covenants Associated With
Privately Maintained Storm Drainage Facilities"has been created for the proposed stormwater facilities.
The applicant will need to complete the form, record the signed and notarized document with the
County Auditor's office, and deliver a copy of the recorded document to Mason County Public
Works for monitoring and administration. A copy of the unsigned document is included in the
Attachments.
Minimum Requirement#11: FINANCIAL LIABILITY
Performance bonding or other appropriate financial instruments shall be required for all projects to ensure
compliance with these standards.
NA—Mason County has not indicated that a financial instrument will be required.
3 Marley L.Young,Consulting Engineer
Project No.2005-22
Lilliwaup Post Office site
II. PLOT PLAN
Engineer's Civil Drawings have been developed for the project showing the location of the improvements
and the layout of the proposed Permanent Stormwater Control BAIN, and an Erosion/Sediment Control
on. B reference these drawings are made apart o this report.
Plan to be used Burin constructs g p ,f P
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III. PRELIMINARY CONDITIONS SUMMARY
See Section I, Project Overview.
IV. OFF-SITE ANALYSIS
(No off-site analysis is required. See Min. Req. 98 above)
Wetlands or Water of the State
This site does not contain wetlands. Hood Canal is located across the highway from the site.
Analysis of the 100-year Flood
This site does not contain or abut a Federal Emergency Management Administration(FEMA)identified
stream and is,therefore,outside any 100-year flood plain.
V. PERMANENT STORMWATER QUALITY CONTROL PLAN
All storm events are collected and directed to the infiltration trench through a grass swale
STORM EVENT DESIGN ASSUMPTIONS
Based on DOE's Stormwater Management Manual:
STORM EVENT
The stormwater program Water Works(software for hydrology by Engenious Systems,Inc.)was
used to model the storm flows,retention, infiltration and releases.
Rain Precipitation(in.)
Six-month,24-hour Storm Event 3.00 (6-mo. @ 64%of 2-yr.)
Two-year,24-hour Storm Event 4.70
Ten-year, 24-hours Storm Event 6.70
Hundred-year, 24-hour Storm Event 9.25
Rainfall choice 1A
Hydrograph SBUH**
** Santa Barbara Urban Hydrograph method
DRAINAGE BASIN
Grove gravelly sandy loam(Gk),5-15 percent slopes
Hydrologic Soil Group A
Infiltration Rate for Pond 6 min./inch
CN#for Post Development Impervious 98
CN#for Pre Development Pervious 55
CN# for Composite Pervious 59.70
NOTE: Given the Storm Event, Soil Type and Land Use,the Runoff Curve Number(CN#)is an
indicator of the total surface and subsurface runoff.
4 Marley L.Young,Consulting Engineer
Project No.2005-22
Lilliwaup Post Office site
POST DEVELOPMENT STORMWATER RUNOFF for 1.24 ACRES
Storm Event 6-month Two-year Ten-year 100-year
Pre Flow cfs 0.016 0.052 0.214 0.516
Pre Volume ac ft 0.121 0.057 0.132 0.250
Post Flow cfs 0.394 0.359 0.638 1.037
Post volume ac ft 0.148 0.154 0.257 0.401
Water Depth ft 0.05 0.32 1.58 3.88
INFILTRATION-TRENCH—TOTAL INFILTRATION
Floor Length ft 105
Floor Width ft 10.5
Side Slopes: Vertical slope
Infiltration Rate min./inch 6.0
CHECKING FOR COMPLIANCE TO STREAMBANK EROSION CONTROL
Total infiltration satisfies Streambank Erosion Control.
GRASS SWALE
Floor length: ft 100
Floor width: ft 2
Maximum Grass swale Slope: 1%
Side Slopes: 3H to 1V for 10"depth
Cubic Feet Per Second: 6 mo.=0.174 cfs; 100-yr.= 1.037 cfs
Manning's Roughness Coefficient(n)6-mo.(n)=0.06; 100-yr. (n)=0.06
Velocity in Bioswale: 6-mo.=0.75 fps; 100-yr.= 1.31fps
Min. Water Depth: 6-mo. =0.17 ft; 100-yr.=0.39 ft.
Min. Grass swale Depth: 0.83 ft. (double the 100-yr.water depth)
Refer to Supporting Calculations for further details.
VI. SPECIAL REPORTS AND STUDIES
None
VII. BASIN AND COMMUNITY PLANNING
NA
VUL PERMITS
Agency Permit/Approval
Mason County Building Permit
IX. EROSION and SEDEWENT CONTROL PLAN
Temporary Erosion Control
This project includes temporary erosion control. See Civil Drawings. The disturbance to the property is
minimal. The types of soils are sandy,gravelly, and do not lend themselves to migration.
Erosion control will use the stabilization of the construction entrance and hay/straw bales.
Because of the gravelly texture of the soil, silt and soil migration is not considered to become a problem.
5 Marley L.Young,Consulting Engineer
Project No.2005-22
Lilliwaup Post Office site
Project Description/Existing Site Conditions
Refer to Section I, Project Overview.
Adjacent Areas Impacts
NA—No impact anticipated.
SCS Soils Description
The Soil conservation Service—Soil Survey of Mason County Series 1951,No. 9,Issued September
1069, shows this property having soils type Grove gravelly sandy loam(Gk),5-15 percent slopes.
Soils conditions found on the property may not match exactly the soils described by SCS.
Critical Areas
No critical areas have been identified on this site.
Erosion and Sediment Control Measures
Minimum Requirements
Mason County has adopted the Department of Ecology"Stormwater Management Manual for the Puget
Sound Basin. All projects that disturb more than one acre must develop a Permanent Stormwater Quality
Control Plan. (Mason County Ordinance 141-97)
EROSION AND SEDIMENT CONTROL REQUIREMENTS
The existing soils on the site have been classified by the SCS as Grove gravelly sandy loam(Gk), 5-15
percent slopes. I feel that the erosion and sediment control system hereinafter proposed will adequately
provide the necessary erosion and sediment protection.
The fifteen large parcel minimum requirements specified by DOE are:
#1: Stabilization and Sediment Trapping
All exposed and unworked soils shall be stabilized by suitable application of BMPs. From October 1 to
April 30,no exposed and unworked soils shall remain unstabilized for more than 2 days. From May 1 to
September 30,no exposed and unworked 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.
#2: Delineate Clearing and Easement Limits
The clearing limits shall be defined by the owner.
#3: Protection of Adjacent Properties
The underlying soils have very little potential for migration. Protecting adjacent property from damage
from sediment deposition does not appear to be a problem.
#4: Timing and Stabilization of Sediment Trapping Measures
Sediment traps will be used as necessary.
#5: Cut and Fill Slopes
Minor side slopes will be 2 or 3:1. Rock gravity walls will be used for slopes steeper than 2:1. The face
of the rock gravity walls are to be %:1.
#6: Controlling Off-site Erosion
Off-site erosion is not anticipated to become an issue.
6 Marley L.Young,Consulting Engineer
Project No.2005-22
Lilliwaup Post Office site
#7: Stabilization of Temporary Conveyance Channels and Outlets
The water velocity for ground surface flows is not anticipated to reach erosion velocity. All stormwater
will be infiltrated on site.
#8: Storm Drain Inlet Protection
See Civil Drawings for storm drain inlet protection.
#9: Underground Utility Construction
Architectural and Civil drawings put contractor on notice as to the installation requirements of
underground utilities.
#10: Construction Access Routes
Construction vehicles access shall be,whenever possible,limited to one route. Access points shall be
stabilized to minimize the tracking of sediment onto public roads.
There shall be one proposed access to the site for construction purposes. See Civil Drawings for
location and detail.
#11: Removal of Temporary BMPs
All temporary erosion and sediment control BMPs will be removed when final site stabilization is
achieved.
#12: Dewatering Construction Sites
Dewatering is not necessary. The soil characteristic is highly porous.
#13: Control of Pollutants Other Than Sediment on Construction Sites
All pollutants other than sediments that occur onsite during construction shall be handled and disposed of
in a manner that does not cause contamination of stormwater.
#14: Maintenance
All temporary and permanent erosion and sediment control BAIN shall be maintained and repaired as
needed to assure continued performance of their intended function.
#15: Financial Liability
Not Applicable to this project.
Permanent Stabilization
At the conclusion of site construction improvements,within seven days permanent site stabilization shall
be completed by spreading seed and mulch on all exposed soils to establish a ground cover.
Use the following recommended seed mixture for erosion control,or a County-approved alternate seed
mixture.
Proportions Percent Percent
Name by Weight Purity Germination
Redtop(Agrostis alba) 10 percent 92 90
Annual rye(Lolium multiflorum) 40 percent 98 90
Chewing fescue 40 percent 97 80
(Festuca rubra commutata)
(Jamestown.Banner,Shodow,or Koket)
White dutch clover(Trifolium repens) 10 percent 96 90
7 Marley L.Young,Consulting Engineer
Project No.2005-22
Lilliwaup Post Office site
The following is a guide for use of recommended mulch material:
Application Rates Depth
Mulch Quality Per 1000 Per of
Material Standards Sq.Feet Acre Application Remarks
Gravel,Crushed Washed 3/,to 9 CY 3 inches Good for short slope and
Stone 1%2-inch around woody plants and
ornaments. Use where
Subject to foot traffic.
Hay or straw Air dry.Free from 75-1001bs 1.5 to Min.2 inches Use where needed for more
weed seed and pounds 2.5 tons than 3 mos. Subject to
coarse material. (Approx. blowing—keep moist or
2 in.thick) 90-120 Bales When used on critical areas,
Wood Fiber No growth organism 25 to 30 1000 to 1500 double application rate.
Cellulose(Partly inhibiting factors pounds pounds Apply with hydromulcher.
Digested wood factors. No tie-down required.
fibers)
Stormwater Management Considerations
Please see Section i, "Permanent Stormwater Quality Control Plan"for a complete description of the
stormwater management plan.
Maintenance
The responsibility for maintaining the facilities will lie with the owners of the property or their assigns.
For maintenance recommendations please see Section U,, "Operation and Maintenance Manual"below.
Calculations
Calculations are briefly described in Section V, "Permanent Stormwater Quality Control Plan"above,
and included in the attached Supporting Calculations.
X. BOND QUANTITIES WORKSHEET,RETENTION/DETENTION FACILITY SUMMARY
SHEET AND SKETCH,AND DECLARATION OF COVENANT
Bond Quantities Worksheet—NA
Retention/Detention Facility Summary sheet—NA
Declaration of Covenant—To ensure that the proposed stormwater control facilities are
adequately operated and maintained, a "Declaration of Covenants Associated with Privately
Maintained Storm Drainage Facilities"will be required to be created for the proposed stormwater
facilities. The applicant will need to complete the form, record the signed and notarized
document with the County Auditor's office, and deliver a copy of the recorded document to
Public Works for monitoring and administration. . A copv of the unsigned document is included in
the Attachments.
XI. OPERATION& MAINTENANCE MANUAL
MAINTENANCE PLAN
The responsibility for maintaining the facilities will lie with the owners of the property or their assigns
(e.g.,Contractor). The facilities are designed to minimize the need for extensive maintenance.
MAINTENANCE OF TEMPORARY EROSION BMPs DURING CONSTRUCTION
During construction the major maintenance activity is to inspect the construction entrance and hay/straw
bales. If the drainage carries mud or debris, silt fences or hay/straw bales should be placed in the path of
the drainage to eliminate any siltation from exiting the project site.
8 Marley L.Young,Consulting Engineer
Project No.2005-22
Lilliwaup Post Office site
All erosion and sediment control BMPs installed shall be inspected regularly,especially after any
large storm. Maintenance, including removal and proper disposal of sediment should be done as
necessary. (Generally sediment that restricts the sheet flow or infiltration must be removed.)
MAINTENANCE OF PERMANENT STORMWATER CONTROL FACILITIES
The Type I catch basin shall be inspected semi-yearly for the accumulation of oil and sediment. The
catch basin should be cleaned with oil-absorbing materials every six months,spring and fall, if warranted.
In the fall inspect the grass swale to assure that the grass will stand 4-5 inches through winter. Inspect the
swale to assure that it is clear of debris that would block flow and that the flow is spread throughout the
width of the swale. In the spring the swale shall be inspected for black or brown discoloration or staining
caused by fluids. The stained soil and sod should be replaced and the old material disposed of in the
appropriate manner.
Monitoring wells are installed in the infiltration trench. Frequent inspection is recommended. The
purpose of inspection is to monitor the infiltration draw-down in the trench. If the trench is dewatered
within 24 hours for a 10-year storm and 48 hours for a I00-year storm,the trench is working as designed.
If dewatering is slower, steps must be taken to keep oils and silts from entering the trench. This is
accomplished by frequent cleaning of the grass swale and catch basins.
CHANGED CONDITIONS: The conclusions and recommendations in this report are based on my
interpretation of site conditions,and the expectation that my onsite exploratory efforts adequately define
the surface and sub-surface conditions throughout the site. In the event that the scope of the project or
location of the improvements or surface/subsurface conditions differ from those I relied on in this report,I
should be advised. At that time,a review of the changed conditions will be made and alternative or
remedial recommendations given as requested.
This Stormwater Site Plan has been prepared by:
-)T) 0-.4'� C�ra'kA -CA�
Marley L.Young, . .,P.L. .
7
9 Marley L.Young,Consulting Engineer
Project No.2005-22
Lilliwaup Post Office
ATTACHMENTS
Marley L.Young,Consulting Engineer
Project No.2005.22
Lilliwaup Post Office
DECLARATION OF COVENANTS ASSOCIATED WITH
PRIVATELY MAINTAINED STORM DRAINAGE FACILITIES
(Copy of unsigned document)
Marley L.Young,Consulting Engineer
Project No.2005-22
RETURN ADDRESS GRANTOR(S)(Last,First and Middle Initials)
GRANTEE: MASON COUNTY
DEPARTMENT OF PUBLIC WORKS
DECLARATION OF COVENANTS ASSOCIATED WITH
PRIVATELY MAINTAINED STORM DRAINAGE FACILITIES
Declaration of Covenant
In consideration of approval of the development known as the Lilliwaup,Washington Post Office,
relating to real property legally described as follows:
County Assessor's Property Tax Parcel Number 32330-51-56013
The undersigned, as owner(s),covenant and agree that:
1. If at any time Mason County reasonably determines that maintenance or repair work is
required to be done to the existing,approved storm drainage facilities installed on the property described
above and located outside of any public right-of-way (which will mean repair and or clean out of the
existing system only to the same standards as originally installed and approved), the Director of the
Department of Public Works shall give the current owners seven days notice that the County intends to
perform such maintenance or repairs,or to have them performed by others.
If the current owners have not completed or are not diligently pursuing the repair or
maintenance of the system and it becomes necessary for Mason County to perform the work,the current
owners will assume responsibility for the cost of such maintenance or repair and will reimburse the
County within thirty days of receipt of the invoice. Overdue payments will require payment of interest
at the current legal rte for liquidated judgments, and any costs or fees incurred by the County, should
any legal action be required to collect such payments, will be borne by the parties responsible for said
reimbursements.
2. If at any time Mason County reasonably determines that the existing and approved storm
drainage system on the property poses a hazard to life and limb, or endangers property, or adversely
affects the safety and operations of a public way, due to failure, damage or non-maintenance of the
existing on-site storm system, and that the situation is so adverse as to preclude written notice to said
owners the Director of the Department of Public Works may take the measures necessary to eliminate
the hazardous situation (which will mean repair or clean out of the existing system only to the same
standards as originally installed and approved)provided the Director has first made a reasonable effort
to locate said owner before acting.
g
The current owners will assume responsibility for the cost of such maintenance or repair; and
will reimburse the County within thirty days of receipt of the invoice. Overdue payments will require
payment of interest at the current legal rate for liquidated judgments, and any costs or fees incurred by
the County, should any be borne by the parties responsible for said reimbursements.
3. The owner shall keep the Mason County public Works Department informed at all times as
to the name,address and telephone number of the contact person responsible for the performance of
maintenance or repair work to the storm drainage facilities.
These covenants are intended to protect the value and desirability of the real property described
above, and to benefit all the citizens of Mason County. They shall run with the land and be binding on
all parties having or acquiring from the current owners or their successors, any right, title or interest
therein, and to the benefit of all the citizens of Mason County.
Signature Signature
Owner Owner
City, State,Zip City, State,Zip
Phone: Phone:
STATE OF WASHINGTON,
ss. (INDIVIDUAL ACKNOWLEDGMENT)
County of MASON
Notary Public in and for the State of Washington,residing at
do hereby certify that on this day of ,20___,personally appeared
before me to me know to be the individual_
described in and who executed the within instrument and acknowledged that signed and sealed the
same as free and voluntary act and deed for the uses and purposes herein mentioned.
GIVEN UNDER MY HAND AND OFFICIAL SEAL this day of , 20_.
Notary Public in and for the State of Washington,residing at
in said County.
My Commission expires
Lilliwaup Post Office
SUPPORTING
CALCULATIONS
Marley L.Young,Consulting Engineer
Project No.2005-22
5/17/05 8 :2 : 38 am Marley Young Engineer page 1
LILLIWAUP POST OFFICE
PRLIMINARY REVIEW OF STORMWATER CONTROL
BASIN SUMMARY
BASIN ID: lA NAME: 1/2
SBUH METHODOLOGY
TOTAL AREA. . . . . . . : 0 . 82 Acres BASEFLOWS : 0 . 00 cfs
RAINFALL TYPE. . . . : TYPEIA PERV IMP
PRECIPITATION. . . . : 3 . 00 inches AREA. . : 0 . 82 Acres 0 .00 Acres
TIME INTERVAL. . . . : 5 . 00 min CN. . . . : 55 . 00 0 .00
TC. . . . . 15 . 00 min 0 .00 min
ABSTRACTION COEFF: 0 .20
PEAK RATE : 0 .02 cfs VOL: 0 . 01 Ac-ft TIME: 1120 min
BASIN ID: 1B NAME: 2
SBUH METHODOLOGY
TOTAL AREA. . . . . . . : 0 . 82 Acres BASEFLOWS : 0 . 00 cfs
RAINFALL TYPE. . . . : TYPEIA PERV IMP
PRECIPITATION. . . . : 4 . 70 inches AREA. . : 0 . 82 Acres 0 .00 Acres
TIME INTERVAL. . . . : 5 . 00 min CN. . . . : 55 . 00 0 .00
TC. . . . . 15 . 00 min 0 . 00 min
ABSTRACTION COEFF: 0 .20
PEAK RATE : 0 .05 cfs VOL: 0 .06 Ac-ft TIME : 1120 min
BASIN ID: 1C NAME : 10
SBUH METHODOLOGY
TOTAL AREA. . . . . . . : 0 . 82 Acres BASEFLOWS : 0 . 00 cfs
RAINFALL TYPE. . . . : TYPEIA PERV IMP
PRECIPITATION. . . . : 6 .70 inches AREA. . : 0 . 82 Acres 0 .00 Acres
TIME INTERVAL. . . . : 5 .00 min CN. . . . : 55 . 00 0 .00
TC. . . . . 15 .00 min 0 . 00 min
ABSTRACTION COEFF: 0 .20
PEAK RATE: 0 .21 cfs VOL: 0 .13 Ac-ft TIME : 480 min
BASIN ID: 1D NAME: 100
SBUH METHODOLOGY
TOTAL AREA. . . . . . . : 0 . 82 Acres BASEFLOWS : 0 . 00 cfs
RAINFALL TYPE . . . . : TYPEIA PERV IMP
PRECIPITATION. . . . : 9 .25 inches AREA. . : 0 . 82 Acres 0 .00 Acres
TIME INTERVAL. . . . : 5 .00 min CN. . . . : 55 . 00 0 . 00
TC. . . . . 15 . 00 min 0 . 00 min
ABSTRACTION COEFF: 0 .20
PEAK RATE: 0 .52 cfs VOL: 0 .25 Ac-ft TIME: 480 min
5/17/05 8 :2 :38 am Marley Young Engineer page 2
LILLIWAUP POST OFFICE
PRLIMINARY REVIEW OF STORMWATER CONTROL
BASIN SUMMARY
BASIN ID: la NAME: 1/2 developed
SBUH METHODOLOGY
TOTAL AREA. . . . . . . : 0 . 82 Acres BASEFLOWS : 0 . 00 cfs
RAINFALL TYPE . . . . : TYPElA PERV IMP
PRECIPITATION. . . . : 3 . 00 inches AREA. . : 0 .54 Acres 0 .28 Acres
TIME INTERVAL. . . . : 5 . 00 min CN. . . . : 59 . 70 98 .00
TC. . . . . 5 .00 min 5 . 00 min
ABSTRACTION COEFF: 0 .20
PEAK RATE : 0 . 17 cfs VOL: 0 .08 Ac-ft TIME : 480 min
BASIN ID: lb NAME: 2 developed
SBUH METHODOLOGY
TOTAL AREA. . . . . . . : 0 . 82 Acres BASEFLOWS : 0 .00 cfs
RAINFALL TYPE . . . . : TYPElA PERV IMP
PRECIPITATION. . . . : 4 . 70 inches AREA. . : 0 .54 Acres 0 .28 Acres
TIME INTERVAL. . . . : 5 .00 min CN. . . . : 59 . 70 98 .00
`ITC. . . . . 5 . 00 min 5 .00 min
ABSTRACTION COEFF: 0 .20
PEAK RATE: 0 .36 cfs VOL: 0 . 15 Ac-ft TIME : 480 min
BASIN ID: 1c NAME: 10 developed
SBUH METHODOLOGY
TOTAL AREA. . . . . . . : 0 . 82 Acres BASEFLOWS : 0 .00 cfs
RAINFALL TYPE. . . . : TYPElA PERV IMP
PRECIPITATION. . . . : 6 . 70 inches AREA. . : 0 .54 Acres 0 .28 Acres
TIME INTERVAL. . . . : 5 .00 min CN. . . . : 59 .70 98 .00
TC. . . . . 5 . 00 min 5 .00 min
ABSTRACTION COEFF: 0 .20
PEAK RATE : 0 . 64 cfs VOL: 0 .26 Ac-ft TIME: 480 min
BASIN ID: ld NAME: 100 developed
SBUH METHODOLOGY
TOTAL AREA. . . . . . . : 0 . 82 Acres BASEFLOWS : 0 . 00 cfs
RAINFALL TYPE. . . . : TYPElA PERV IMP
PRECIPITATION. . . . : 9 .25 inches AREA. . : 0 .54 Acres 0 .28 Acres
TIME INTERVAL. . . . : 5 . 00 min CN. . . . : 59 . 70 98 .00
TC. . . . . 5 .00 min 5 .00 min
ABSTRACTION COEFF: 0 . 20
PEAK RATE : 1 .04 cfs VOL: 0 .40 Ac-ft TIME: 480 min
5/17/05 8 :2 :38 am Marley Young Engineer page 3
LILLIWAUP POST OFFICE
PRLIMINARY REVIEW OF STORMWATER CONTROL
STAGE STORAGE TABLE
TRAPEZOIDAL BASIN ID No. TT3
Description: INFILTRATION POND
Length: 35 .00 ft . Width: 10 .50 ft .
Side Slope 1 : 0 Side Slope 3 : 0
Side Slope 2 : 0 Side Slope 4 : 0
Infiltration Rate: 2 . 00 min/inch
STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE---->
(ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft-
100.00 0.0000 0.0000 101.05 385.88 0.0089 102.10 771.75 0.0177 103.15 1158 0.0266
100.05 18.375 0.0004 101.10 404.25 0.0093 102.15 790.13 0.0181 103.20 1176 0.0270
100.10 36.750 0.0008 101.15 422.63 0.0097 102.20 808.50 0.0186 103.25 1194 0.0274
100.15 55.125 0.0013 101.20 441.00 0.0101 102.25 826.88 0.0190 103.30 1213 0.0278
100.20 73.500 0.0017 101.25 459.38 0.0105 102.30 845.25 0.0194 103.35 1231 0.0283
100.25 91.875 0.0021 101.30 477.75 0.0110 102.35 863.63 0.0198 103.40 1250 0.0287
100.30 110.25 0.0025 101.35 496.13 0.0114 102.40 882.00 0.0202 103.45 1268 0.0291
100.35 128.63 0.0030 101.40 514.50 0.0118 102.45 900.38 0.0207 103.50 1286 0.0295
100.40 147.00 0.0034 101.45 532.88 0.0122 102.50 918.75 0.0211 103.55 1305 0.0300
100.45 165.38 0.0038 101.50 551.25 .0.0127 102.55 937.13 0.0215 103.60 1323 0.0304
100.50 183.75 0.0042 101.55 569.63 0.0131 102.60 955.50 0.0219 103.65 1341 0.0308
100.55 202.13 0.0046 101.60 588.00 0.0135 102.65 973.88 0.0224 103.70 1360 0.0312
100.60 220.50 0.0051 101.65 606.38 0.0139 102.70 992.25 0.0228 103.75 1378 0.0316
100.65 238.88 0.0055 101.70 624.75 0.0143 102.75 1011 0.0232 103.80 1397 0.0321
100.70 257.25 0.0059 101.75 643.13 0.0148 102.80 1029 0.0236 103.85 1415 0.0325
100.75 275.63 0.0063 101.80 661.50 0.0152 102.85 1047 0.0240 103.90 1433 0.0329
100.80 294.00 0.0067 101.85 679.88 0.0156 102.90 1066 0.0245 103.95 1452 0.0333
100.85 312.38 0.0072 101.90 698.25 0.0160 102.95 1084 0.0249 104.00 1470 0.0337
100.90 330.75 0.0076 101.95 716.63 0.0165 103.00 1103 0.0253
100.95 349.13 0.0080 102.00 735.00 0.0169 103.05 1121 0.0257
101.00 367.50 0.0084 102.05 753.38 0.0173 103.10 1139 0.0262
5/17/05 8 :2 : 38 am Marley Young Engineer page 4
LILLIWAUP POST OFFICE
PRLIMINARY REVIEW OF STORMWATER CONTROL
---------------------------------------------------------------------
---------------------------------------------------------------------
STAGE STORAGE TABLE
Infiltration Rating Curve for Storage Struct TT3
STAGE <-INFILTRATION-> STAGE <-INFILTRATION-> STAGE <-INFILTRATION-> STAGE <-INFILTRATION->
(ft) ---cfs-- ------- (ft) ---cfs-- ------- (ft) ---cfs-- ------- (ft) ---cfs-- -------
--------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------
100.00 0.2552 101.05 0.3216 102.10 0.3879 103.15 0.4543
100.05 0.2584 101.10 0.3247 102.15 0.3911 103.20 0.4574
100.10 0.2615 101.15 0.3279 102.20 0.3942 103.25 0.4606
100.15 0.2647 101.20 0.3310 102.25 0.3974 103.30 0.4638
100.20 0.2678 101.25 0.3342 102.30 0.4006 103.35 0.4669
100.25 0.2710 101.30 0.3374 102.35 0.4037 103.40 0.4701
100.30 0.2742 101.35 0.3405 102.40 0.4069 103.45 0.4732
100.35 0.2773 101.40 0.3437 102.45 0.4100 103.50 0.4764
100.40 0.2805 101.45 0.3468 102.50 0.4132 103.55 0.4795
100.45 0.2836 101.50 0.3500 102.55 0.4164 103.60 0.4827
100.50 0.2868 101.55 0.3532 102.60 0.4195 103.65 0.4859
100.55 0.2900 101.60 0.3563 102.65 0.4227 103.70 0.4890
100.60 0.2931 101.65 0.3595 102.70 0.4258 103.75 0.4922
100.65 0.2963 101.70 0.3626 102.75 0.4290 103.80 0.4953
100.70 0.2994 101.75 0.3658 102.80 0.4322 103.85 0.4985
100.75 0.3026 101.80 0.3690 102.85 0.4353 103.90 0.5017
100.80 0.3058 101.85 0.3721 102.90 0.4385 103.95 0.5048
100.85 0.3089 101.90 0.3753 102.95 0.4416 104.00 0.5080
100.90 0.3121 101.95 0.3784 103.00 0.4448
100.95 0.3152 102.00 0.3816 103.05 0.4480
101.00 0.3184 102.05 0.3848 103.10 0.4511
5/17/05 8 :2 :38 am Marley Young Engineer page 5
LILLIWAUP POST OFFICE
PRLIMINARY REVIEW OF STORMWATER CONTROL
STAGE DISCHARGE TABLE
OVERFLOW WEIR ID No. W
Description:
Ratio (h:lv) : 3 .2100 Weir length: 4 .0000 ft .
El : 105 . 50 ft . Weir Increm: 0 . 05
STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE--->
(ft) ---Cfs-- ------- (ft) ---Cfs-- ------- (ft) ---Cfs-- ------- (ft) ---cfs-- -------
-------------------------------------------------------------
105.50 0.0000 105.65 0.8215 105.80 2.5267 105.95 5.0151
105.55 0,1489 105.70 1.3016 105.85 3.2694 106.00 6.0195
105.60 0.4341 105.75 1.8706 105,90 4.0987
5/17/05 8 :2 :40 am Marley Young Engineer page 6
LILLIWAUP POST OFFICE
PRLIMINARY REVIEW OF STORMWATER CONTROL
LEVEL POOL TABLE SUMMARY
MATCH INFLOW -STO- -DIS- <-PEAK-> OUTFLOW STORAGE
<--------DESCRIPTION---------> (cfs) (cfs) --id- --id- <-STAGB> id (cfs) VOL (cf)
-------------------------------------------------------------------------------------
-------------------------------------------------------------------------------------
1/2 .................. . .... ... 0.02 0.17 TT3 W 100.05 9 0.17 18.38 cf
2 ...... .............. ..... ... 0.05 0.36 TT3 W 100.32 10 0.28 116.43 cf
10 ........................... 0.21 0.64 TT3 W 101.58 11 0.36 581.03 cf
100 .......................... 0.52 1.04 TT3 W 103.88 12 0.50 1425.07 cf
5/17/05 8 :2 :40 am Marley Young Engineer page 7
LILLIWAUP POST OFFICE
PRLIMINARY REVIEW OF STORMWATER CONTROL
HISTORY OF HYDROGRAPH ACTIVITY
Date of Session: 5/1/05 2:19:33 pm
CLEAREIS
MOVE lA to 1
0.0163 cfs 0.0132 ac-ft 18.67 hrs
MOVE 1B to 2
0.0515 cfs 0.0568 ac-ft 18.67 hrs
MOVE 1C to 3
0.2143 cfs 0.1318 ac-ft 8.00 hrs
MOVE 1D to 4
0.5161 cfs 0.2500 ac-ft 8.00 hrs
MOVE la to 5
0.1739 cfs 0.0790 ac-ft 8,00 hrs
MOVE lb to 6
0.3590 cfs 0.1538 ac-ft 8.00 hrs
MOVE lc to 7
0.6377 cfs 0.2566 ac-ft 8.00 hrs
MOVE ld to 8
1.0370 cfs 0.4010 ac-ft 8.00 hrs
LPOOL 1 11/21 1 5 TT3 W 9
Description MatchQ PeakQ Sto Dis PkStq OutQ hyd Volume
1/2 0.02 0.17 TT3 W 100.05 0.17 9 18.38 cf
LPOOL 2 121 2 6 TT3 W 10
Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume
2 0.05 0.36 TT3 W 100.32 0.28 10 116.43 cf
LPOOL 3 110" 3 7 TT3 W 11
Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume
10 0.21 0.64 TT3 W 101.58 0.36 11 581.03 cf
LPOOL 4 11001 4 8 TT3 W 12
Description MatchQ PeakQ Sto Dis PkStq OutQ hyd Volume
100 0.52 1.04 TT3 W 103.88 0.50 12 1425.07 cf
SPLIT W 1 13 17
0.0000 cfs 0.0000 ac-ft 0.00 hrs
0.1737 cfs 0.0790 ac-ft 8.08 hrs
SPLIT W 2 14 18
0.0000 cfs 0.0000 ac-ft 0.00 hrs
f ,
5/17/05 8 :2 :40 am Marley Young Engineer page 8
LILLIWAUP POST OFFICE
PRLIMINARY REVIEW OF STORMWATER CONTROL
HISTORY OF HYDROGRAPH ACTIVITY
0,2752 cfs 0.1538 ac-ft 8.17 hrs
SPLIT W 3 15 19
0.0000 cfs 0.0000 ac-ft 0,00 hrs
0.3551 cfs 0,2566 ac-ft 8,25 hrs
SPLIT W 4 16 20
0.0000 cfs 0.0000 ac-ft 0,00 hrs
0.5003 cfs 0.4010 ac-ft 8.33 hrs
End program file E:\EGENIO"1\LILIWAU3,pgm
Date of Session: 5/17/05 7:59:21 am
8iJ SWALE CALCULATIONS 6 MONTH STORM EVENT BIO SWALE CALCULATIONS 100 YEAR STORM EVENT
Owner
1 of 2 Page 2 of 2
LILUWAUP,'WASHINGTON POST OFFICE Owner LILLIWAUP,'WASHINGTON POST OFFICE
Project# Project# 0
Remarks No Swale 6 month,24 hour storm events Remarks No Swale 100 year,24 hour storm events
Design for Swale Capacity Design for Swale Capacity
Date May 17,2005 Date May 17,2005
Q fordhe max.year storm evert to use the:Swale 6 Month Q for the max.year storm event to use the Swale 6 Mon. 1.806476
Q= 0.1739 cfs cubic feet per second Q= 1.037 cfs cubic feet per second
y= 0.166 Max.Sio Swale water depth An feet 1.806476 y= 0.385 Max.Sio Swale water depth in feet 100 Yr 1.80129
s= 0.01 Slope of Bio Swale in feet per foot s= 0.01 Slope of Bio Swale in feet per foot
Z= 3 Swale side skope 3:1 Z= 3 Swale side slope 3:1
Note: The free board above the storm event,is double the 100-year event depth Note: The free board above the storms event is double the 100-year event depth
(See Manual-II1-6-19:SC-14.) (See Manuall-III-6-19:SC-14.) OR 0.77 FT
Use DOE Manual,page 11I-&13 Formula(6-9) iUse DOE Manual,page III-6-1'3 Formula(6-9)
b=[,Qn/(1.486)1(y11.667)'(s"0.5)]-Zy b=,[Qn/(1.496)i(y"1.667)`(s"0.5)]-Zy
Note-Assume Q is directed to both ends and CD is,in middle. Note-Assume Q is directed to both ends and CD is in middle,
Q = Q.1739 Q 1.037
n = 0.06 n = 0.06
(See Marming's(Roughness Coefficients(n)IV Highway Channel and (See Manning's,Roughness Coefficients(n)IV Highway Channel and
Swales with Maintained Vegetation) Swales with Maintained Vegetation)
A.Depth of flow up to 0.7 feet: A.Depth of flow up to 0.7 feet:
1.'''Bermuda grass-Length 4 to 6'inches=n=.09 to.05; Use=0,06 1.Bermuda grass-Length 4 to 6'inches=n=.09 to.05; Uso=0.06
On = 0.010434 On 0:06222
(y,^1.667) = 0j05011 (y"1.667) = 0.203687
(5'!0.5) = 0.1 (s^0.5) 0.1
(-Zy) _ -0.498 (-Zy) _ -1.155
b = 0.903238 b = 0.900645
Swale has a maximum lenth of 100 ft. Swale must be widened to Swale has a maximum lenth of 100 ft. Swale imust be wideroed,to
compensate for shorter length,than 2W. - See Page 111.6-20,paragraph CO-1 compensate for shorter length than 200'. - See Page 111-.6-20,paragraph CO-1
200/ 100 x 0.903238 = 1,.806476 feet design width 20GI 100 x 0.900645 = 1.80129 feet design width
2 ft.use 2 ft.use
=iow Velocity Check ::low Velocity Check
v=QIA v=QlA
A=Cross Sectional Area= by+,Z`(y"2) A=Cross Sectional Area= by+Z'(y^2)
A= 0.232605 A= 0.791423
Therefore
Therefore
v= 0.747618 fps ok v= 1.310297 fps < 5:00 fps =O.K.
WORK ORDER • PUBLIC WORKS DEPT.
uy, date; — fq Work Order
PERMIT M —o o7a- a Dom N006-000-7 3 Numben
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'type of Wod(.#
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AGENCY/COMPANY
BIUJNG ADDRESS
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EQUIPMENT IISEM TOTAL n
MATEMYL VS M --'•"
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Rum Hoom sum _ T��OTAL$
EWPMENT USED: Qom ( TWAL li
MATERIAL USED:
J) BILLED DATE TOTAL ALL
PAID DATE..._.._..,_ RE04_..._,.,_,�,,,CKK