HomeMy WebLinkAboutR_TIR_Drainage_Report_170621_V1DRAINAGE REPORT
TACO BELL
Renton, Washington
4225 NE 4th Street
Renton, Washington 98059
Prepared For:
City of Renton
Design Engineer:
Jeremy White
Project Manager:
Rafia Darwish
Design Date:
June, 2017
Project Number:
2016088.28
____________________________ ________________
Darrin Kotecki, P.E. Date
07/31/18
06/21/17
1
TABLE OF CONTENTS
Technical Information Report (TIR) Overview and Background . . . . . . . . . . . . . . . . . . . . 2
Section 1 – Project Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Section 2 – Conditions and Requirements Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Section 3 – Offsite Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Section 4 – Flow Control and Water Quality Facility Analysis and Design . . . . . . . . . . . . 4
Section 5 – Conveyance System Analysis and Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4‐5
Section 6 – Special Reports and Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Section 7 – Other Permits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Section 8 – CSWPPP Analysis and Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Section 9 – Bond Quantities, Facility Summaries, and Declaration of Covenant . . . . . . . . . 5
Section 10 – Operations and Maintenance Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Attachment A – ESM Consulting Engineers Technical Information Report (previously approved TIR)
Attachment B – Pipe Sizing Spreadsheet, Design Calculations and Variables, and Drainage Area
Delineations
Attachment C – Operations and Maintenance Manual
Attachment D – Special Requirement #4 ‐ Source Controls
Attachment E – Bond Quantity Spreadsheet
2
TECHNICAL INFORMATION REPORT (TIR) OVERVIEW AND BACKGROUND
The following technical information report is based on two previously approved technical information
reports, both located within Attachment A. Attachment A is a TIR completed by ESM Consulting
Engineers, LLC dated December 1, 2014. Within the ESM Consulting Engineers TIR are references to
another TIR by Barghausen, Inc, dated April 15, 2003, which is also located in Attachment A. Section
references throughout this drainage report conducted by GPD Group references the TIR conducted by
ESM Consulting Engineers, which may then in turn reference the TIR conducted by Barghausen, Inc.
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
See Figure 1.5 of Attachment A of the previously approved TIR prepared by ESM Consulting Engineers,
LLC dated December 1, 2014.
Section 1 – Project Overview (Taco Bell Site Specific, by GPD)
The proposed Taco Bell project is located southwest of the intersection of NE 4th Street and Whitman
Court NE, just west of the United States Post Office, in the City of Renton, Washington. The project is
0.73 acres in size and zoned CA (Commercial Arterial).
The surface of the existing site contains asphalt pavement outlined on the outside edge by a curb and
gutter section, with roughly graded gravel areas located toward the center of the asphalt pavement. The
edges of the property are covered by roughly graded mulches, grass, and a pedestrian wood chip trail.
The developable portion of the existing site is sloped toward existing catch basins located throughout
the existing project site. The stormwater captured by these existing catch basins is then carried south
through a previously approved and constructed pipe network to a previously approved and constructed
water quality/detention pond. On the west side of the property is a wetland, which drains off site to the
south.
The surface of the proposed site will consist of a 1,856 square foot Taco Bell structure, as well as a drive‐
thru lane, parking lot, landscaping and a rain garden to serve as a flow control BMP. Per Section 5.2.1.3
of the 2009 King County Surface Water Design Manual, the site is required to treat 3,180 square feet of
the target impervious area. This will be accomplished by the installation of a rain garden sized to treat
3,908 square feet of impervious area. The portion of rain water not being captured by the rain garden
will be routed to existing catch basins and pipe networks throughout the site along with one proposed
yard inlet to help convey storm water to the previously approved and constructed existing detention
pond. For access, this project will utilize the existing driveway access point on NE 4th Street.
A storm water detention/water quality pond has also been previously approved and constructed, and is
located to the southwest of the site. The detention/water quality pond will discharge to the west to the
onsite wetland. See Appendix A of Attachment A for the previously approved TIR prepared by
Barghausen, Inc.
According to Appendix B of Attachment A, the site is underlain by native soils consisting of fill soils and
Vashon Recessional Outwash. Additionally, according to the USDA NRCS Web Soil Survey, the entire site
is underlain by Alderwood Gravelly Sandy Load, which varies from 8% to 15%.
3
Section 2 – Conditions and Requirements Summary (Taco Bell Site Specific, By GPD)
Special Requirement #4 Source Controls:
The proposed Taco Bell is a commercial building, therefore water quality source controls shall be
implemented. The applicable source controls can be found in Attachment D
Special Requirement #5 Oil Control:
The proposed Taco Bell is considered a high use site according to the 2009 King County Surface Water
Design Manual, and therefore the project must treat runoff from the high‐use portion of the site using
oil control treatment options located in Chapter 6 of the 2009 King County Surface Water Design
Manual. The proposed Taco Bell will implement Oil Control Option – 1 Catch Basin Insert throughout the
site to sufficiently meet special requirement #5.
Section 3 – Offsite Analysis (Taco Bell Site Specific, by GPD)
Pre‐Developed Conditions: Soils in the area are Alderwood soils, which are classified as glacial till. The
existing offsite drainage occurs at the western to northwestern portions of the project location. Water
landing within an existing combination of mulch, wood chip and brush areas along the western portion
of the project are carried to an existing wetland that runs north and south which is also located on the
western portion of the project. Water landing within the existing pavement in the northwestern portion
of the project currently flows down the existing asphalt drive to the existing drainage network located
throughout and within NE 4th Street.
Post Developed Conditions: The proposed project consists of developing the 0.73 acre lot located at the
southwest corner of the NE 4th Street and Whitman Court NE intersection, but does not alter the existing
curb along the western portion of the project. With no curb alterations occurring in these locations, the
existing mulch, wood chip and brush areas will continue to drain to the existing wetland along the
western portion of the project location, identical to pre developed conditions. The water landing within
the northwestern portion of the project will flow down the proposed drive and enter the existing
drainage network located in NE 4th Street, mimicking the pre‐developed offside flow. The increase in
water landing within the pavement that will reach the drainage network located in NE 4th Street is
negligible (0.2% of overall project area) due to grading techniques used to maximize flow to the
proposed rain garden.
All onsite drainage captured within the project site will be carried to the proposed rain garden or the
existing conveyance systems located at the southern end of the project. The storm water passing
through the rain garden will be conveyed north through a small system of pipes and will outlet into an
existing manhole. The storm water captured by the yard inlet and existing catch basins will be relayed
further south to a previously approved and constructed water quality/detention pond, independent of
the wetland located at the western portion of the project location.
4
Section 4 ‐ Flow Control and Water Quality Facility Analysis and Design (Taco Bell Site Specific, by
GPD)
The proposed Taco Bell lot consists of approximately 68% impervious surface, and is considered a Large
Lot High Impervious Surface according 2009 King County Surface Water Design Manual. This
classification requires the site to treat 10% of the total lot areas stormwater runoff. The site has a total
area of 31,863 square feet, therefore the site is required to treat 3,186 square feet of target impervious
area.
A rain garden was chosen as the flow control BMP and is located in the northwestern portion of the lot.
The rain garden is required to have a minimum water storage volume equivalent to 3 inches of runoff
depth from the impervious surface area. In other words, the volume in cubic feet shall equal 0.25 times
the square footage of the impervious surface area treated. Therefore, the minimum rain garden volume
can be calculated as (0.25 feet)*(3,186 square feet) = 797 cubic feet.
The minimum square footage treatment requirement was accomplished by using curb cuts along the
drive thru and access drive, allowing 3,908 square feet of target impervious area stormwater to sheet
flow into the flow control BMP. Sizing of the rain garden was then calculated to account for not only the
target impervious area draining to the rain garden, but the impervious surfaces surrounding the rain
garden as well, totaling a storage volume of 977 cubic feet.
Section 5 – Conveyance System Analysis and Design (Taco Bell Site Specific, by GPD)
A conveyance analysis was performed for proposed pipe located throughout the project site. An analysis
of the existing previously approved pipe network was not conducted. The pipe sizing spreadsheet,
design calculations and variables, and drainage area delineations are located in Attachment B. The
proposed conveyance system’s parameters are as follows:
Backwater was analyzed using a Microsoft Excel spreadsheet, using rational methodology to analyze
each sub‐delineation area. The project is not located near a location with an IDF curve table created;
therefore the peak rainfall intensity values were calculated per section 3.2.1 of the King County,
Washington Surface Water Design Manual, 2009 Edition.
Developed Land Uses Used:
Pavement/Roofs (C=0.90)
Gravel (C=0.80)
Wood Chip (C=0.30)
Lawns (C=0.25)
Rainfall Data Used:
25 Year: 3.42 inches
100 Year: 3.90 inches
5
Time of Concentration:
Time of concentration is set at the King County, Washington Surface Water Design Manual, 2009
Edition minimum of 6.3 minutes to add conservatism to the system design.
The System was designed to convey the 100 year storm with no capacity or backwater issues. This was
done to determine that no flooding or backwater would occur.
Section 6 – Special Reports and Studies (Refer to ESM Consulting TIR)
See Section 6 of Attachment A for the previously approved Special Reports and Studies information
prepared by ESM Consulting Engineers, LLC dated December 1, 2014.
Section 7 – Other Permits (Refer to ESM Consulting TIR)
See Section 7 of Attachment A for the previously approved Other Permits information prepared by
ESM Consulting Engineers, LLC dated December 1, 2014.
Section 8 – CSWPPP Analysis and Design (Refer to ESM Consulting TIR)
See Section 8 of Attachment A for the previously approved CSWPPP Analysis and Design
information prepared by ESM Consulting Engineers, LLC dated December 1, 2014.
Section 9 – Bond Quantities, Facility Summaries, and Declaration of Covenant (Refer to ESM
Consulting TIR)
See Section 9 of Attachment A for the previously approved Facility Summaries, and Declaration of
Covenant information prepared by ESM Consulting Engineers, LLC dated December 1, 2014.
See Attachment E for the City of Renton Bond Quantities Worksheet.
Section 10 – Operations and Maintenance Manual (Taco Bell Site Specific, by GPD)
The Operations and Maintenance Manual can be located in Attachment C.
Attachment A
Attachment B
Page 1 of 1Date: Date: Project Name: 25 0.009 for HDPE pipeProject Number: 100xxxx Denotes Water Surface Elevation Governs Sheet No. 1of11 2 3 7 10 11 12 13 14 15 16 17 18 19 20MH, CB, IB or HDWDelineation Color SideRunoff Coef.Size of Pipe (in.)Length (ft.)Slope (%)Invert at StructureInvert at Next Downstream StructureMean Velocity (ft/sec)Just Full CapacityRim ElevationFriction SlopeHead Loss (ft.)Elevation of Hydraulic GradientNo.AAtCtCi25i100CCACAQ25Q100L S Feet FeetVmcfs FeetsfH FeetSTM-103 Green 0.04 6.3 6.3 2.75 3.19 0.64 0.03 0.08 0.10 12 66 1.80 387.85 386.68 1.90 6.90 390.85 0.0000 0.0000388.16STORM SEWER COMPUTATION SHEET (TRADITIONAL DESIGN - FOR PERV PVMT OVERFLOW BACKUP ONLY)Calculated by: JWChecked by: 66/15/2017IDF Distribution for King County, WashingtonHydraulic Gradient 100 Year Frequency8Year H.G.Just Full Capacity 25 Year Frequency Taco Bell - Renton9Discharge in cfs (Column 6 x Column 8)Year DesignDrainage Area (acres)Time of Concentration (min.)Rainfall (inches/hour)452016088.28Column 7 x Column 4Mannings "n"O:\2016\2016088\28 - Renton, WA\Dwg\Construction Documents\Civil\SWM\Pipe Sizing Calcs.xls
C
0.10
0.15
0.20
0.25
0.30
0.80
0.90
1.00
aR bR
1.58 0.58
2.44 0.64
2.66 0.65
2.61 0.63
kR
2.5
4.7
7.0
10.1
15.0
20.0
Forest w/ heavy ground litter & meadow
10 Years
25 Years
100 Years
Land Cover Category
Runoff Coefficients ‐ "C" Values for the Rational Method
Coefficients for the Rational Method "iR" Equation
Design Storm Return Frequency
2 Years
Open Water
General Land Covers
Land Cover
Dense Forest
Light Forest
Pasture
Lawns
Paved area and shallow gutter flow
kR Values for Tt Using the Rational Method
Fallow or minimum tillage cultivation
Short grass pasture and lawns
Nearly bare ground
Grassed waterway
Playgrounds
Gravel Areas
Pavement/Roofs
2.00
2.90
3.42
3.90
Return Period Rainfall Intensities
Return Period PR
2 Year
10 Year
25 Year
100 Year
C Area (ac.) C Area (ac.)
0.90 0.419 0.90 0.497
0.80 0.150 0.80 0.000
0.30 0.027 0.30 0.027
0.25 0.136 0.25 0.208
Runoff Coefficient Calculations
Proposed
Land Cover
Pavement
Gravel
Wood Chip
Lawns
Total Acreage
Land Cover
Pavement
Gravel
Wood Chip
Lawns
0.732
Existing
Time of Concentration Calculations
Exisitng Proposed
Length T1 (ft)
Runoff Coefficient 0.70
Total Acreage 0.732
Runoff Coefficient 0.74
Length T2 (ft)
0.37
47
Length T1 (ft)45
Slope T1 (ft/ft)0.035
KR T1 4.7
T1 Total (min)0.85
Tused (min)6.3
Slope T1 (ft/ft)
KR T1
29
0.077
4.7
T1 Total (min)
Peak Rainfall Intensity Calculations
TT (t1+T2)
Tused (min)
20.0
0.34
0.71
6.3
Slope T2 (ft/ft)0.013
KR T2
T2 Total (min)
1.09
2.18
2.75
3.19
Existing Proposed
Return Frequency IR
2 Year
Return Frequency IR
2 Year 1.09
10 Year 2.18
25 Year 2.75
100 Year 3.19
10 Year
25 Year
100 Year
Peak Flow Calculation
Existing Proposed
Return Frequency
2 Year
Return Frequency
2 Year
10 Year
25 Year
100 Year
QR (cfs)
0.56
1.12
1.41
1.64
10 Year
25 Year
100 Year
QR (cfs)
0.59
1.17
1.48
1.72
R/WR/WR/WR/WR/WR/WR/W ST ST ST ST ST ST ST ST ST ST ST ST ST ST
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STSTSTSTSTSTSTE E E
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EP/LEEEEEP/L P/L P/LP/
LP/
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NE 4TH STREET WHITMAN CT. NE (53 FEET WIDE)(WIDTH VARIES)
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P/L
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STP/LEXISTING STREAMCONTRACT DATE:
BUILDING TYPE:
PLAN VERSION:
SITE NUMBER:
STORE NUMBER:
TACO BELL
4225 NE 4TH STREET
RENTON, WA 98059
CALIF SOL
04.05.17
CALIF SOL
MED40
312178/441895
2016088.28
520 South Main Street, Suite 2531
Akron, OH 44311
330.572.2100 Fax: 330.572.2102
EXISTING
DRAINAGE
MAP
1 of 3
LEGEND
(SEE SHEET C-001 FOR GENERAL LEGEND)
0
40
20
10
1"=20'
Horizontal Scale in Feet
EXISTING GRAVEL
C = 0.80
A = 0.150 AC
EXISTING PAVEMENT
C = 0.90
A = 0.419 AC
EXISTING VEGETATION
C = 0.25
A = 0.136 AC
EXISTING WOOD CHIP
C = 0.30
A = 0.027 AC
EXISTING DRAINAGE AREA TOTALS
C = 0.74
A = 0.732 AC
Tc = 6.3 MIN
TIME OF CONCENTRATION
ROUTE, Tc = 6.3 MIN
R/WR/WR/WR/WR/WR/WR/W ST ST ST ST ST ST ST ST ST ST ST ST ST ST
STSTSTSTSTSTSTSTSTSTST
STSTSTSTSTSTSTE E E
E
GASGASGASGASGASGASGASGAS
GASGASGASGASGASGASE
EP/LEEEEEP/L P/L P/LP/
LP/
LP/LP/LR/W
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t
w
g g g
st
st
st st
C
w
NE 4TH STREET WHITMAN CT. NE (53 FEET WIDE)(WIDTH VARIES)
w
VASHON CT NEVASHON CT NEww
P/L
P/LP/LP/LP/LP/L
P/L R/WR/WR/WR/WR/Wcoco
S
T
S
T
S
T
STg
P/LEXISTING STREAMSTSTSTST
ST
CONTRACT DATE:
BUILDING TYPE:
PLAN VERSION:
SITE NUMBER:
STORE NUMBER:
TACO BELL
4225 NE 4TH STREET
RENTON, WA 98059
CALIF SOL
04.05.17
CALIF SOL
MED40
312178/441895
2016088.28
520 South Main Street, Suite 2531
Akron, OH 44311
330.572.2100 Fax: 330.572.2102
PROPOSED
DRAINAGE
MAP
2 of 3
LEGEND
(SEE SHEET C-001 FOR GENERAL LEGEND)
0
40
20
10
1"=20'
Horizontal Scale in Feet
PROPOSED PAVEMENT
C = 0.90
A = 0.497 AC
PROPOSED VEGETATION
C = 0.25
A = 0.208 AC
PROPOSED WOOD CHIP
C = 0.30
A = 0.027 AC
PROPOSED DRAINAGE AREA TOTALS
C = 0.70
A = 0.732 AC
Tc = 6.3 MIN
TIME OF CONCENTRATION
ROUTE, Tc = 6.3 MIN
R/WR/WR/WR/WR/WR/WR/W ST ST ST ST ST ST ST ST ST ST ST ST ST ST
STSTSTSTSTSTSTSTSTSTST
STSTSTSTSTSTSTE E E
E
E
EP/LEEEEEP/L P/L P/LP/
LP/
LP/LP/LR/W
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sn
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C
w
NE 4TH STREET WHITMAN CT. NE (53 FEET WIDE)(WIDTH VARIES)
w
VASHON CT NEVASHON CT NEww
P/L
P/LP/LP/LP/LP/L
P/L
2 136547
1
13 STOPDRIVE-THRU21
13 R/WR/WR/WR/WR/W12.0'co
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T
S
T
S
T
STg
GASGASGASGAS
5.0'
J
DO
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O
T
E
N
T
E
R15.0'392P/LEXISTING STREAM5.0'STSTST391ST
ST
391
390
392 392
392393392391392CONTRACT DATE:
BUILDING TYPE:
PLAN VERSION:
SITE NUMBER:
STORE NUMBER:
TACO BELL
4225 NE 4TH STREET
RENTON, WA 98059
CALIF SOL
04.05.17
CALIF SOL
MED40
312178/441895
2016088.28
520 South Main Street, Suite 2531
Akron, OH 44311
330.572.2100 Fax: 330.572.2102
PIPE SIZING
EXHIBIT
3 of 3
LEGEND
0
40
20
10
1"=20'
Horizontal Scale in Feet STM-103 PIPE SIZNG
C = 0.64
A = 0.035 AC
TARGET IMPERVIOUS AREA = 3,908 SQUARE FEET
Attachment C
Attachment D
Please reference the following sheets for the required source controls per the 2016 King County
Stormwater Pollution Prevention Manual.
Stormwater Pollution Prevention Manual • King County 27
A-1 Required Best Management Practices for all Properties with Commercial Activities
The following Best Management Practices (BMPs) are required for all commercial, industrial,
agricultural, public, or residential properties with commercial activities in unincorporated King County.
Best Management Practices (BMPs) are required by King County Code 9.12. If the BMPs included here
are not enough to prevent contamination of stormwater, you will be required to take additional
measures.
Required BMPs:
Clean and Maintain Storm Drainage System
• Evaluate the condition of the catch basin by checking the amount of sediment in the bottom of the sump.
Catch basins must be cleaned out when the solids, trash, and debris in the sump reaches one–half of the
depth between the bottom of the sump and the bottom of the lowest inflow or outflow pipe connected to
the catch basin or is at least 6 inches below this point.
• Hire a professional drainage contractor to inspect and maintain your system or clean the system yourself. If
there is sediment or other debris in the drainage pipes, then a professional contractor must be hired to flush
or jet out the pipes.
• Small amounts of floating oil can be soaked up with oil absorbent pads, bagged and disposed of as solid
waste.
• Up to one cubic yard of nonhazardous solid material may be disposed of as solid waste in your regular
garbage. If you exceed this threshold hire a professional drainage contractor. All of the solids and stagnant
water collected from catch basin sumps must be disposed of properly. None of the sump contents can
be flushed into the catch basin outflow pipe. Depending on the nature of the pollutants in the sump, and
the associated types of activities taking place on the site, the sump contents may need to be handled
as contaminated waste. Contractors who perform catch basin clean–out services are required to follow
appropriate disposal requirements.
• Clean and maintain catch basins annually. Sites with activities generating a lot of sediments and other debris
will have to inspect and clean out their catch basins more often. Frequent sweeping of paved parking and
storage areas will save time and money in maintaining the drainage system.
• Other components of drainage systems such as ponds, tanks, and bioswales must also be maintained. If this
maintenance is beyond your ability, contractors are available to complete this work.
Label All Storm Drain Inlets on Your Property
• Stencil or apply storm drain markers adjacent to storm drains to help prevent the improper disposal of
pollutants. If the storm drain grate is stamped with warnings against polluting, then additional marking may
not be required if there is no evidence of pollutants being dumped or washed into the storm drain.
Stormwater Pollution Prevention Manual • King County28
Eliminate Illicit Connections to the Storm Drainage System
• Connections to the storm drainage system that convey substances other than stormwater are prohibited.
Examples are connections from internal floor drains, HVAC systems, industrial processes, sinks, and toilets.
• Illicit connections must be immediately removed, permanently plugged or re–plumbed.
• The discharge must be re–plumbed so that it goes to the sanitary sewer, a septic system, an on–site
treatment system, or a holding tank for off–site disposal. There are restrictions on what can be disposed of
to the sanitary sewer and septic systems. You may be required to do additional investigation to determine
where all stormwater and non–stormwater discharges go. This may include smoke, dye, and chemical
testing or closed circuit television inspection.
Additional Information:
• Drainage System Maintenance Contractors Information Sheet
• For stencils and instructions or to determine if you have an illicit connection, contact King County
Stormwater Services at 206–477–4811 or kingcounty.gov/stormwater.
Stormwater Pollution Prevention Manual • King County 35
A-8 Storage or Solid and Food Wastes (Including Cooking Grease)
This refers to garbage dumpsters and outdoor waste containers such as cooking oil/grease receptacles.
Best Management Practices (BMPs) are required by King County Code 9.12. If the BMPs included here
are not enough to prevent contamination of stormwater, you will be required to take additional
measures.
Required BMPs:
• Store wastes in leak–proof containers with solid lids.
• Keep dumpsters closed except when adding waste.
• Used cooking oil/grease containers should be labeled with their contents.
• Clean up any spills immediately using dry methods. Grease cannot be left on the ground.
• Have spill cleanup materials nearby.
• Use a lid or cover when transporting cooking oil/grease containers from kitchens to outside grease
containers.
• Ensure that drip pans or absorbent materials are used whenever grease containers are emptied by vacuum
trucks or other means.
• Dispose of collected cooking oil/grease as garbage if it is not being recycled. Do not dispose of fats, oils or
grease (FOG) into the sanitary sewer or septic system.
Required Routine Maintenance:
• Keep the area around the grease container clean and free of debris.
• Check storage containers frequently for leaks and to ensure that lids are on securely.
• Replace leaking or damaged containers. Contact waste hauler for replacements.
• Sweep and clean the storage area as needed if it is paved. Do not hose down waste storage areas.
• When cleaning or rinsing waste containers, dispose of all wastewater into a sanitary sewer. If no sewer is
available, store in a holding tank, dead end sump, or truck off site to an approved disposal location.
Additional Information:
• Disposal Information Sheet
For more information or assistance contact the King County Stormwater Services at 206–477–4811 and
visit kingcounty.gov/stormwater.
Stormwater Pollution Prevention Manual • King County 39
A-12 Cleaning or Washing of Food Service Areas and Equipment
Best Management Practices (BMPs) are required by King County Code 9.12. If the BMPs included here are
not enough to prevent contamination of stormwater, you will be required to take additional measures.
Required BMPs:
• The cleaning of cooking equipment, filter screens, floor mats etc. must be done indoors.
• All wash and rinse water must be discharged to the sanitary sewer or the septic system.
• Floor mop water must not be poured outside. Instead pour it into a sink or toilet.
• Wash and rinse water containing fats, oils or grease (FOG) may require pretreatment to remove FOG prior to
disposal to the sanitary sewer or septic system.
• Do not dispose of wash or rinse waster containing floor stripping or disinfectant chemicals into the septic
system as they can seriously inhibit wastewater treatment and cause the system to fail.
For more information or assistance contact the King County Stormwater Services at 206–477–4811 and
visit kingcounty.gov/stormwater.
Stormwater Pollution Prevention Manual • King County50
A-20 Concrete and Asphalt Application
This applies to sites where asphalt is applied or small amounts of concrete that is hand mixed on site.
The application of premixed concrete must follow the standards in the King County Surface Water
Design Manual.
Best Management Practices (BMPs) are required by King County Code 9.12. If the BMPs included here are
not enough to prevent contamination of stormwater, you will be required to take additional measures.
Required Best Management Practices (BMPs):
• Use drip pans, ground cloths, heavy cardboard or plywood wherever concrete, asphalt, asphalt emulsion and
drips are likely to spill, such as beneath discharge points from equipment.
• Cover and contain all nearby storm drains at the beginning of the workday. Drain covers and other
containment devices are commercially available to keep runoff out of the storm drainage system. All solids
collected must be disposed of properly at the end of the workday (or more frequently) prior to removing the
containment or cover device(s).
• Contain and collect the slurry from exposed aggregate washing. Never allow the slurry to get into a storm
drain, ditch, roadway shoulder or gutter. Use a storm drain cover, inlet protection or other containment
device, such as a hand–dug, lined sump to direct and contain slurry. All collected runoff must be disposed of
properly.
• Do not discharge concrete, slurry, or rinse water into gutters, storm drains, or drainage ditches or onto the
paved surface of a roadway or driveway.
• Designate an area onsite where hand tools will be cleaned and the water collected for disposal. Commercial
products and services are also available for concrete, slurry, and rinse water containment and disposal.
• Do not use diesel fuel for cleaning or prepping asphalt tools and equipment.
Required Routine Maintenance:
• Sweep the pouring area at the end of the job or more frequently if needed. Collect loose aggregate chunks
and dust. Do not hose down the area to a storm drain.
Supplemental BMPs:
• A catch basin insert may be necessary for sediment removal. Catch basin inserts require frequent
maintenance to be effective.
Additional Information:
• Covering Information Sheet
• Containment Information Sheet
• Disposal Information Sheet
• Catch Basin Insert Information Sheet
For more information or assistance contact the King County Stormwater Services at 206–477–4811 and
visit kingcounty.gov/stormwater.
• King County Surface Water Design Manual
Appendix D – Concrete Handling
• King County Surface Water Design Manual
Appendix D – Concrete Washout Area
Stormwater Pollution Prevention Manual • King County56
A-26 Landscaping Activities and Vegetation Management
Best Management Practices (BMPs) are required by King County Code 9.12. If the BMPs included here
are not enough to prevent contamination of stormwater, you will be required to take additional
measures.
Required BMPs:
• Train employees on the proper use and application of fertilizers and pesticides.
• Never apply pesticides and fertilizers if it is raining or about to rain.
• Do not apply pesticides within 100 feet of surface waters such as lakes, ponds, wetlands, streams, and
stormwater conveyance ditches unless the application is approved and permitted by the Washington State
Department of Ecology.
• Determine the proper fertilizer application for the types of soil and vegetation involved. Follow
manufacturers’ recommendations and label directions.
• Clean up any spills immediately.
• Remove weeds/vegetation in stormwater ditches by hand or other mechanical means and only use
chemicals as a last resort.
• Do not blow vegetation or other debris into the storm drain system, sidewalks, or street. Dispose of collected
vegetation by recycling or composting.
• Use mulch or other erosion control measures when soils are exposed for more than one week during the dry
season or two days during the rainy season.
• Ensure sprinkler systems do not “overspray” vegetated areas resulting in the excess water discharging into
the storm drain system.
• New and expanding golf courses must have a Golf Course Management Plan as described in addressed in
the King County Golf Course BMP Manual
Supplemental BMPs:
• Use integrated pest management (IPM); a comprehensive approach to the use of pesticides is the most
effective BMP measure that can be taken for herbicide, insecticide, and fungicide use.
• Test soils to determine the correct fertilizer application rates.
• Use mechanical methods of vegetation removal rather than applying herbicides.
• Use native plants in landscaping. Native plants do not require extensive fertilizer or pesticide applications.
Stormwater Pollution Prevention Manual • King County60
A-29 Building Repair, Remodeling, and Construction
Best Management Practices (BMPs) are required by King County Code 9.12. If the BMPs included here
are not enough to prevent contamination of stormwater, you will be required to take additional
measures.
Required BMPs:
• Do not dump any substance, wash water or liquid waste on the pavement or ground.
• Use drop cloths when painting, scraping, and sandblasting and properly dispose of collected material daily.
• Use a drop cloth, drip pan, or tub for activities such as paint mixing and tool cleaning.
• Clean paint brushes and tools covered with water–based paints in sinks connected to sanitary sewers or
in portable containers that can be dumped into a sanitary sewer. Brushes and tools covered with non–
water–based paints, finishes, or other materials must be cleaned in a manner that enables collection of used
solvents (e.g., paint thinner, turpentine, etc.) for recycling or proper disposal. Solvents may not be disposed
of to the sanitary sewer. Never dispose of any wash water to a storm drain.
• Use a storm drain cover, filter fabric, or other runoff control mechanism if dust, grit, wash water, or other
pollutants may escape the work area. Check runoff control mechanisms daily, and replace as necessary. Drain
covers, filter fabric, and other containment devices are commercially available if effective runoff control
cannot otherwise be provided.
• Cover trash bins and dumpsters and ensure they are not leaking.
• Follow Appendix D of the King County Surface Water Design Manual, “Erosion and Sediment Control
Measures” for dewatering activities.
Required Routine Maintenance:
• Keep spill cleanup materials in a common location on–site. Ensure that employees are familiar with proper
spill cleanup procedures.
• Sweep paved areas to collect loose particles for proper disposal. Wipe up spills with rags or other absorbent
material immediately. Do not hose down the area to a storm drain.
• Store hazardous materials under cover, using items such as tarps or other temporary cover materials.
Supplemental BMPs:
• Recycle or reuse leftover materials.
• Install catch basin inserts to collect excess sediment and debris if necessary. Inspect and maintain catch
basin inserts to ensure they are working correctly.
• Install temporary wheel wash facilities if track out occurs.
Stormwater Pollution Prevention Manual • King County 63
A-31 Vehicle and Equipment Parking and Storage
Best Management Practices (BMPs) are required by King County Code 9.12. If the BMPs included here
are not enough to prevent contamination of stormwater, you will be required to take additional
measures.
Required BMPs:
• Sweep parking lots, storage areas, and driveways as needed to collect dirt, waste, and debris. Do not hose
down the area to the storm drainage system.
• Clean up vehicle and equipment fluid drips and spills immediately.
• Place drip pans below inoperative or leaking vehicles and equipment, including employee vehicles.
• Collect and discharge wash water to a sanitary sewer or haul for offsite disposal if washing/pressure washing
of the parking lot occurs. There are businesses that will clean parking lots and collect water for off–site
disposal. Never drain wash water to the storm drainage system.
• Follow basic sediment controls as outlined in Appendix D (“Erosion and Sediment Control Standards”) of the
King County Surface Water Design Manual for gravel and dirt lots. These types of parking lots may require
additional BMPs to prevent sediment laden water from leaving your site.
Supplemental BMPs:
• Encourage employees to repair leaking personal vehicles.
• Encourage employees to carpool or use public transit through incentives.
• Encourage customers to use public transit by rewarding valid transit pass holders with discounts.
• Install catch basin inserts to collect excess sediment and oil if necessary. Inspect and maintain catch basin
inserts to ensure they are working correctly.
Additional Information:
• Disposal Information Sheet
• Catch Basin Insert Information Sheet
For more information or assistance contact the King County Stormwater Services at 206–477–4811 and
visit kingcounty.gov/stormwater.
Stormwater Pollution Prevention Manual • King County64
A-32 Sidewalk Maintenance
Best Management Practices (BMPs) are required by King County Code 9.12. If the BMPs included here are
not enough to prevent contamination of stormwater, you will be required to take additional measures.
Required BMPs:
• Sweep sidewalks as needed to collect loose dirt and debris rather than blowing or pushing it into the street
or gutter or hosing it down. Collected materials must be disposed of as solid waste.
• Clean individual stains instead of washing the entire sidewalk if possible.
• Collect wash water and dispose of into the sanitary sewer or take off site for appropriate disposal if soaps or
other cleaners are used. If only water is used, install a catch basin insert or filter cloth in order to collect all
solids and debris.
• Use a minimum amount of sand or deicing salts and sweep up any remaining granules when the snow and
ice have melted.
Additional Information:
• Disposal Information Sheet
• Storage of Liquid Materials in Portable Containers – See Activity Sheet A-3
• Containment Information Sheet
For more information or assistance contact the King County Stormwater Services at 206–477–4811 and
visit kingcounty.gov/stormwater.
Stormwater Pollution Prevention Manual • King County74
A-41 Wheel Wash and Tire Bath Track Out Control
This activity applies to commercial and industrial operations where materials may be tracked off the
property. If a rocked construction–type entrance for unpaved site, or routine sweeping/vacuuming of
paved site, does not control mud and sediment track out; a wheel wash system must be installed.
Best Management Practices (BMPs) are required by King County Code 9.12. If the BMPs included here
are not enough to prevent contamination of stormwater, you will be required to take additional
measures.
Required Best Management Practices (BMPs):
• Install a portable wheel wash system
OR
• Permanent wheel wash system as described in Appendix D, Chapter D.3.4.3 of the King County Surface Water
Design Manual
Required Routine Maintenance:
• Change water as necessary. Dispose of wheel wash water to appropriate disposal location.
• Maintain the appropriate level of water per design.
Additional Information:
For more information or assistance contact the King County Stormwater Services at 206–477–4811 and
visit kingcounty.gov/stormwater.
Stormwater Pollution Prevention Manual • King County 75
A-42 Potable Water Line Flushing, Water Tank Maintenance and Hydrant Testing
Chemicals used in line flushing and tank maintenance are highly toxic to aquatic organisms and can
degrade receiving waters
Best Management Practices (BMPs) are required by King County Code 9.12. If the BMPs included here are
not enough to prevent contamination of stormwater, you will be required to take additional measures.
Required BMPs:
• Discharge water to the sanitary sewer if super chlorination or chemical treatment is used as part of flushing.
If sanitary sewer is not available, the water may be infiltrated to the ground as long as it is dechlorinated to a
total residual chlorine concentration of 0.1 ppm or less and water quality standards are met, a diffuser is used
to prevent erosion, and the water does not cross property lines.
• Discharging water (chlorinated or dechlorinated) to a stormwater drainage system requires approval from
King County Water and Land Resources (WLRD). The water must be dechlorinated to a total residual chlorine
concentration of 0.1 ppm or less and pH adjusted if necessary. Water must be volumetrically and velocity
controlled to prevent resuspension of sediments in the MS4. Contact WLRD for approval.
Additional Information:
For more information or assistance contact the King County Stormwater Services at 206–477–4811 and
visit kingcounty.gov/stormwater.
Stormwater Pollution Prevention Manual • King County76
A-44 Dust Control for Commercial Operations
This activity applies to existing manufacturing and commercial operations as opposed to new
construction or land development. Material handling activities may include concrete crushing, cement
mixing, commercial composting, stone grinding, and wood milling.
Best Management Practices (BMPs) are required by King County Code 9.12. If the BMPs included here
are not enough to prevent contamination of stormwater, you will be required to take additional
measures.
Required BMPs:
• Sweep paved areas where dust and erodible materials accumulate. Use vacuum sweepers to minimize
generation of airborne dust and for more efficient dust removal.
• Clean equipment and vehicles that leave the property to prevent dust and track out of material. Create a
designated wash area to collect and properly dispose of the wash water. Never wash down equipment or
vehicles to the storm drainage system.
• Train employees in the proper operating procedures to minimize dust accumulation.
Supplemental BMPs–if the Above are Not Sufficient:
• Use dust filtration and collection systems such as bag house filters.
• Use water spray to flush dust accumulations to an approved treatment system or the sanitary sewer where
available and allowed by the local sewer authority and the King County Industrial Waste Program.
• Use approved dust suppressants such as those listed in the King County Surface Water Design Manual,
Appendix D, Erosion and Sediment Control Standards.
• When pH levels in stormwater rise above 8.5, the pH must be adjusted to the acceptable range of 6.5 to
8.5. Refer to the King County Surface Water Design Manual Appendix D Sections D.2.2.7 and D.2.2.8 for
information on pH adjustment.
Additional Information:
• Department of Ecology Publication “Techniques for Dust Prevention and Suppression,” #96–433. Please note
that not all dust suppressants are appropriate for use near storm drainage systems or surface waters.
• Contact Puget Sound Clean Air Agency and/or the Washington State Department of Ecology for air pollution
control regulations.
For more information or assistance contact the King County Stormwater Services at 206–477–4811 and
visit kingcounty.gov/stormwater.