HomeMy WebLinkAbout30-TIR_16062_1612202016 D. R. STRONG Consulting Engineers Inc. Bethany Corner
Technical Information Report Renton, Washington
TECHNICAL INFORMATION REPORT
BETHANY CORNER SHORT PLAT
TABLE OF CONTENTS
SECTION I ...................................................................................................................... 4
Project Overview ......................................................................................................... 4
Predeveloped Site Conditions ..................................................................................... 4
Developed Site Conditions .......................................................................................... 4
King County Area, Washington .................................................................................. 14
AgC—Alderwood gravelly sandy loam, 8 to 15 percent slopes .............................. 14
SECTION II ................................................................................................................... 16
Conditions and Requirements Summary ................................................................... 16
Conditions of Approval............................................................................................... 18
SECTION III .................................................................................................................. 19
Off-Site Analysis ........................................................................................................ 19
Task 1: Define and Map Study Area ...................................................................... 19
Task 2: Resource Review ...................................................................................... 20
Task 3: Field Inspection ......................................................................................... 29
Task 4: Drainage System Description and Problem Descriptions .......................... 30
Task 5: Mitigation of Existing or Potential Problems .............................................. 31
SECTION IV .................................................................................................................. 37
Flow Control Analysis and Water Quality Design ...................................................... 37
Existing Site Hydrology .......................................................................................... 37
Developed Site Hydrology ...................................................................................... 39
Performance Standards ............................................................................................. 42
Flow Control System.................................................................................................. 43
Water Quality Treatment System ............................................................................... 50
SECTION V ................................................................................................................... 52
Conveyance System Analysis and Design ................................................................ 52
SECTION VI .................................................................................................................. 61
Special Reports and Studies ..................................................................................... 61
SECTION VII ................................................................................................................. 62
Other Permits, Variances and Adjustments ............................................................... 62
SECTION VIII ................................................................................................................ 63
CSWPPP Analysis and Design (Part A) .................................................................... 63
SWPPP Plan Design (Part B) .................................................................................... 63
SECTION IX .................................................................................................................. 65
Bond Quantities, Facility Summaries, and Declaration of Covenant .......................... 65
2016 D. R. STRONG Consulting Engineers Inc. Bethany Corner
Technical Information Report Renton, Washington
Stormwater Facility Summary Sheet.......................................................................... 66
SECTION X ................................................................................................................... 68
Operations and Maintenance Manual ........................................................................ 68
APPENDICES ............................................................................................................... 69
Appendix “A” Legal Description ................................................................................. 70
Appendix “B” CSWPPP ............................................................................................. 71
Appendix “C” Bond Quantity Worksheet .................................................................... 72
List of Figures
Figure 1 TIR Worksheet .................................................................................................. 6
Figure 2 Vicinity Map ..................................................................................................... 11
Figure 3 Drainage Basins, Subbasins, and Site Characteristics ................................... 12
Figure 4 Soils ................................................................................................................ 13
Figure 5 City of Renton Topography Map ..................................................................... 21
Figure 6 City of Renton Coal Mine Hazard Areas Map.................................................. 22
Figure 7 City of Renton Flood Hazards Map ................................................................. 23
Figure 8 City of Renton Streams and Wetlands Map .................................................... 24
Figure 9 City of Renton Landslide Hazards Map ........................................................... 25
Figure 10 City of Renton Seismic Hazard Areas Map ................................................... 26
Figure 11 FEMA Map .................................................................................................... 27
Figure 12 King County iMap Drainage Complaints Map................................................ 28
Figure 13 Offsite Analysis Downstream Map ................................................................ 33
Figure 14 Offsite Analysis Downstream Table .............................................................. 34
Figure 15 Predeveloped Area Map................................................................................ 38
Figure 16 Developed Area Map .................................................................................... 41
Figure 17 Detention & Water Quality Facility Details ..................................................... 51
Figure 18 Backwater Analysis Map ............................................................................... 56
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Level One Downstream Analysis Renton, Washington
SECTION I
PROJECT OVERVIEW
The Project is the proposed subdivision of two parcels into nine single-family residential
lots, per the City of Renton’s (City) subdivision process. The Project is located at 16433
& 16451 111th Avenue SE, Renton, Washington (Site) also known as Tax Parcel
Numbers 008800-0570 & -0560. The Project will meet the drainage requirements of the
City of Renton Amendments to the 2009 King County Surface Water Design Manual
(CORSWDMA).
PREDEVELOPED SITE CONDITIONS
The total existing Site area is approximately 79,710 s.f. (1.83 acres). The Site is
currently developed with two single family homes, one trailer home, gravel driveways,
one detached garage, a shed, a concrete foundation, and landscaping.
The Site consists of a shallow grade to the southwest and is contains one Threshold
Discharge Area (TDA). Runoff generated by the TDA gradually sheet flows east to
southwest towards adjacent parcels to the west or is collected by a culvert in the
southwest corner of the Site. Sheet flow over the west property line and culvert flow
from the southwest corner of the Site form the two natural discharge locations for the
Site. The two Natural Discharge Areas (NDAs) of the Site divide it roughly in half with
the northern portion draining to the west and the southern portion draining to the cuvert.
Sheet flow from the western property line is captured by Big Soos Creek on the
adjacent parcels and is conveyed to the south. Runoff through the culvert in the the
southwestern corner of the Site travels for approximately 55 feet in a westerly direction
to a convergence point with Big Soos Creek. Flow from both NDAs converges within
the ¼ mile and therefore the Site can be considered to be within one TDA.
The Project frontage currently drains to a series of ditches and culverts along 111th Ave
SE and converges with Big Soos Creek approximately 160 feet downstream.
DEVELOPED SITE CONDITIONS
The applicant is seeking approval to subdivide 1.83 acres into nine single–family
residential lots (Project), with lot sizes ranging from approximately 5,948 s.f. to 7,119 s.f.
All existing improvements located on the Site will be demolished or removed during plat
construction.
The project is required to meet the City’s Flow Control Duration Standard – Matching
Forested and Basic Water Quality treatment. This standard matches the developed Site
flow durations to the flow durations of pre-developed rates for forested (historical) site
conditions. These standards will be met through the proposed combination detention
and water quality vault. The proposed impervious surface areas are as follows: half
street frontage improvements consisting of a 5’ sidewalk along 111th AVE SE, Road A,
the nine new single-family residences and associated driveways, and Tract A, the storm
water detention facility, will generate approximately 51,486 s.f. of impervious area (1.18
acres). The Project will implement the restricted footprint BMP and the allowable
impervious of each lot will be reduced by 10%.
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Level One Downstream Analysis Renton, Washington
A section of non-target impervious surface along the north side of 111th AVE SE will be
collected by the proposed detention facility. The facility has been designed with this
section being proposed as an offsite flow-through area. This area will be modeled as
impervious in both the predeveloped and developed scenarios. Proposed Site cover
and surfaces are show in Figure 16, Developed Site Conditions. (See Section IV).
The Project proposes to combine runoff from both onsite NDAs and the target frontage
into one detention system and to discharge to the road-side ditch system just upstream
of the confluence with Big Soos Creek. The existing natural discharge locations for the
Site are not suitable for concentrated. No drainage easements are available for
discharge to Big Soos Creek to the west. Discharge to the road-side ditch connects to a
manmade public conveyance system. The proposed discharge location is well within
the ¼ mile of the natural discharge locations.
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FIGURE 1
TIR WORKSHEET
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part 1 PROJECT OWNER AND
PROJECT ENGINEER Part 2 PROJECT LOCATION AND
DESCRIPTION
Project Owner: Mark Seek and Mary Nguyen
Phone: (206) 315-8130
Address: 15233 Manion Way NE, Duvall,
WA 98019
9102 SE 41st Street, Mercer Island, WA 98040
Project Engineer: Jonathan S. Murray, P.E.
Company: D. R. STRONG Consulting
Engineers Inc.
Phone: (425) 827-3063
Project Name: Bethany Corner
City Permit#: PRE16-000651
Location:
Township: 23 North
Range: 05 East
Section: 29
Site Address: 16433 & 16451
111th Avenue SE,
Renton, WA
Part 3 TYPE OF PERMIT APPLICATION Part 4 OTHER REVIEWS AND PERMITS
Landuse Services
Subdivision / Short Subdivision / UPD
Building Services: M/F / Commercial / SFR
Clearing and Grading
Right-of-Way
Other:
DFW HPA Shoreline Mngmt
COE 404 Structural
DOE Dam Safety Rockery/Vault
FEMA Floodplain ESA Section 7
COE Wetlands
Other:
Part 5 PLAN AND REPORT INFORMATION
Technical Information Report
Type of Drainage Review Full / Targeted /
(circle): Large Site
Date (include revision
dates): December 15, 2016
Date of Final:
Site Improvement Plan (Engr. Plans)
Type (circle one): Full / Modified / :
Small Site
Date (include revision
dates):
Date of Final:
Part 6 ADJUSTMENT APPROVALS
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Type (circle one): Standard / Complex / Preapplication / Experimental / Blanket
Description: (include conditions in TIR Section 2)
_____________________________________________________________________________________
_____________________________________________________________________________________
____________________________________________________________________________________
Date of Approval:
Part 7 MONITORING REQUIREMENTS
Monitoring Required: Yes / No
Start Date: TBD
Completion Date
Describe: Monitor discharge location
during construction.
Part 8 SITE COMMUNITY AND DRAINAGE BASIN
Community Plan: Benson
Special District Overlays: N/A
Drainage Basin: Green/Duwamish River Watershed
Stormwater Requirements: Flow Control Duration Standard – Matching Forested and Basic
WQ treatment
Part 9 ONSITE AND ADJACENT SENSITIVE AREAS
River/ Stream: Big Soos Creek
Lake
Wetlands
Closed Depression
Floodplain
Other
Steep Slope
Erosion Hazard
Landslide Hazard
Coal Mine Hazard
Seismic Hazard
Habitat Protection
Part 10 SOILS
Soil Type
AgC
Slopes
8-15%
Erosion Potential
Moderate to Severe
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High Groundwater Table Sole Source Aquifer
other Seeps/Springs
Additional Sheets Attached
Part 11 DRAINAGE DESIGN LIMITATIONS
REFERENCE
Core Requirement #2 – Offsite Analysis
SEPA
Sensitive Area Buffer _______
Additional Sheet Attached
LIMITATION / SITE CONSTRAINT
Part 12 TIR SUMMARY SHEET
Threshold Discharge Area: Site comprised of one TDA
(name or description)
Core Requirements (all 8 apply)
Discharge of Natural Location yes Number of Natural Discharge Locations: 1
Offsite Analysis Level: 1 / 2 / 3 dated: 09/28/2016
Flow Control Level: 1 / 2 / 3 or Exemption Number
(incl. facility summary sheet Small Site BMPS Restricted Footprint
Conveyance System Spill containment located at: TBD
Erosion and Sediment Control ESC Site Supervisor: T/B/D
Contact Phone: T/B/D
After Hours Phone: T/B/D
Maintenance and Operation Responsibility: Private / Public
If Private, Maintenance Log Required: Yes / No
Financial Guarantees and Provided: Yes / No
Liability
Water Quality Type: Basic / Sens Lake / Enhanced Basic / Bog
(include facility summary sheet) or exemption No.
Landscape Management Plan: Yes / No
Special Requirements (as applicable)
Area Specific Drainage Type: CDA / SDO / MDP / BP / LMP / Shared / None
Requirements Name:
Floodplain/Floodway Delineation Type: Major / Minor / Exemption / None
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100-year Base Flood Elevation (or range):
Datum:
Flood Protection Facilities Describe: N/A
Source Control Describe Landuse:
(comm. / industrial landuse) Describe any structural controls:
Oil Control High-use Site: Yes / No
Treatment BMP:
Maintenance Agreement: Yes / No
with whom?
Other Drainage Structures
Describe: Runoff will be collected and conveyed to the wet-vault detention facility
located in Tract A.
Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS
MINIMUM ESC REQUIREMENTS
DURING CONSTRUCTION
Clearing Limits
Cover Measures
Perimeter Protection
Traffic Area Stabilization
Sediment Retention
Surface Water Collection
Dewatering Control
Dust control
Flow Control
MINIMUM ESC REQUIREMENTS
AFTER CONSTRUCTION
Stabilize Exposed Surfaces
Remove and Restore Temporary ESC
Facilities
Clean and Remove All Silt and
Debris, Ensure Operations of
Permanent Facilities
Flag Limits of SAO and open space
Preservation areas
Other
Part 14 STORMWATER FACILITY DESCRIPTIONS (Note: Include Facility Summary and Sketch
Flow Control Type/Description Water Quality Type/Description
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FIGURE 2
VICINITY MAP
The information included on this map has been compiled by King County staff from a variety of sources and is subject to change
without notice. King County makes no representations or warranties, express or implied, as to accuracy, completeness, timeliness,
or rights to the use of such information. King County shall not be liable for any general, special, indirect, incidental, or consequential
damages including, but not limited to, lost revenues or lost profits resulting from the use or misuse of the information contained on
this map. Any sale of this map or information on this map is prohibited except by written permission of King County.
Site
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FIGURE 3
DRAINAGE BASINS, SUBBASINS, AND SITE CHARACTERISTICS
0GRAPHIC SCALE6040201 INCH = 40 FT.
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FIGURE 4
SOILS
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KING COUNTY AREA, WASHINGTON
AGC—ALDERWOOD GRAVELLY SANDY LOAM, 8 TO 15 PERCENT SLOPES
a) Map Unit Setting
• National map unit symbol: 2t626
• Elevation: 50 to 800 feet
• Mean annual precipitation: 20 to 60 inches • Mean annual air temperature: 46 to 52 degrees F
• Frost-free period: 160 to 240 days
• Farmland classification: Prime farmland if irrigated
b) Map Unit Composition
• Alderwood and similar soils: 85 percent
• Minor components: 15 percent
• Estimates are based on observations, descriptions, and transects of the mapunit.
c) Description of Alderwood
(1) Setting
• Landform: Ridges, hills
• Landform position (two-dimensional): Shoulder
• Landform position (three-dimensional): Nose slope, talf
• Down-slope shape: Linear, convex
• Across-slope shape: Convex
• Parent material: Glacial drift and/or glacial outwash over dense glaciomarine deposits
(2) Typical profile
• A - 0 to 7 inches: gravelly sandy loam
• Bw1 - 7 to 21 inches: very gravelly sandy loam
• Bw2 - 21 to 30 inches: very gravelly sandy loam
• Bg - 30 to 35 inches: very gravelly sandy loam
• 2Cd1 - 35 to 43 inches: very gravelly sandy loam
• 2Cd2 - 43 to 59 inches: very gravelly sandy loam
(3) Properties and qualities
• Slope: 8 to 15 percent
• Depth to restrictive feature: 20 to 39 inches to densic material
• Natural drainage class: Moderately well drained
• Capacity of the most limiting layer to transmit water (Ksat): Very low to moderately low (0.00 to 0.06
in/hr)
• Depth to water table: About 18 to 37 inches
• Frequency of flooding: None
• Frequency of ponding: None
• Available water storage in profile: Very low (about 2.7 inches)
(4) Interpretive groups
• Land capability classification (irrigated): None specified
• Land capability classification (nonirrigated): 4s
• Hydrologic Soil Group: B
• Other vegetative classification: Limited Depth Soils (G002XN302WA), Limited Depth Soils
(G002XS301WA), Limited Depth Soils (G002XF303WA)
• Hydric soil rating: No
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d) Minor Components
(1) Everett
• Percent of map unit: 5 percent
• Landform: Eskers, kames, moraines
• Landform position (two-dimensional): Shoulder, footslope
• Landform position (three-dimensional): Crest, base slope
• Down-slope shape: Convex
• Across-slope shape: Convex
• Hydric soil rating: No
(2) Indianola
• Percent of map unit: 5 percent
• Landform: Eskers, kames, terraces • Landform position (three-dimensional): Tread
• Down-slope shape: Linear
• Across-slope shape: Linear
• Hydric soil rating: No
(3) Shalcar
• Percent of map unit: 3 percent
• Landform: Depressions
• Landform position (three-dimensional): Dip
• Down-slope shape: Concave
• Across-slope shape: Concave
• Hydric soil rating: Yes
(4) Norma
• Percent of map unit: 2 percent
• Landform: Depressions, drainageways
• Landform position (three-dimensional): Dip
• Down-slope shape: Concave, linear
• Across-slope shape: Concave
• Hydric soil rating: Yes
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SECTION II
CONDITIONS AND REQUIREMENTS SUMMARY
The Project must comply with the following Core and Special Requirements:
• C.R. #1 – Discharge at the Natural Location: Existing drainage discharges the
Site at one location, maintaining one TDA. The topography indicates that all
stormwater runoff leaves the Site as sheet flow across the west property line.
Runoff is collected by Big Soos Creek which is located on an adjacent property to
the west. Developed runoff will require discharge to a conveyance system.
Discharge from the project will be directed south to the existing conveyance system
along 111th Ave SE. This discharge location converges with flow from the NDA
within the ¼ mile.
• C.R. #2 – Offsite Analysis: Analysis is included in Section III. The Analysis
describes the Site’s runoff patterns in detail.
• C.R. #3 – Flow Control: The Project is required to adhere to Flow Control
Duration Standard – Matching Forested site conditions. One detention/wetvault
will provide flow control as required for the new and replaced impervious and
pervious surfaces. The Site is required to “match the flow duration of pre-developed
rates for forested (historic) site conditions over the range of flows extending from
50% of 2-year up to the full 50-year flow,” (City of Renton 2009 Surface Water
Design Manual Amendment, Sec. 1.2.3.1). A detention vault will accommodate this
requirement.
• C.R. #4 – Conveyance System: New pipe systems are required to be designed
with sufficient capacity to convey and contain (at minimum) the 25-year peak flow,
assuming developed conditions for onsite tributary areas and existing conditions for
any offsite tributary areas. Pipe system structures may overtop for runoff events that
exceed the 25-year design capacity, provided the overflow from a 100-year runoff
event does not create or aggravate a “severe flooding problem” or “severe erosion
problem” as defined in C.R. #2. Any overflow occurring onsite for runoff events up to
and including the 100-year event must discharge at the natural location for the
project site. In residential subdivisions, such overflow must be contained within an
onsite drainage easement, tract, covenant or public right-of-way. This analysis is
shown in Section V.
• C.R. #5 – Erosion and Sediment Control: The Project will provide the seven
minimum ESC measures. A temporary erosion and sedimentation control plan is
presented as part of the engineering construction plan set.
• C.R. #6 – Maintenance and Operations: Maintenance of the proposed storm
drainage facilities will be the responsibility of the City. An Operation and
Maintenance Manual will be included in Section X at the time of construction plan
preparation.
• C.R. #7 – Financial Guarantees: Prior to commencing construction, the Applicant
must post a drainage facilities restoration and site stabilization financial guarantee.
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Level One Downstream Analysis Renton, Washington
For any constructed or modified drainage facilities to be maintained and operated by
the City, the Applicant must: 1) Post a drainage defect and maintenance financial
guarantee for a period of two years, and 2) Maintain the drainage facilities during the
two-year period following posting of the drainage defect and maintenance financial
guarantee.
• C.R. #8 – Water Quality: The Project is required to provide basic water quality
treatment. A combined detention/wetvault will accommodate this requirement.
• S.R. #1 – Other Adopted Area-Specific Requirements: Not applicable for this
Project.
• S.R. #2 – Flood Hazard Area Delineation: Not applicable for this Project.
• S.R. #3 – Flood Protection Facilities: Not applicable for this Project.
• S.R. #4 – Source Control: Not applicable for this Project.
• S.R. #5 – Oil Control: Not applicable for this Project.
• S.R. #6 – Aquifer Protection Area: Site not located within zones 1 and 2, therefore
not applicable for this Project.
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Level One Downstream Analysis Renton, Washington
CONDITIONS OF APPROVAL
Bethany Corner PRE16-000651
TBD
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SECTION III
OFF-SITE ANALYSIS
LEVEL ONE DOWNSTREAM ANALYSIS
DISCLAIMER:
This report was prepared at the request of Mark Seek and Mary Nguyen for the 1.83
acre parcels known as a portion of the Northeast Quarter of Section 29, Township 23
North, Range 5 East, W.M., in King County, Tax Parcel Numbers 008800-0570, & -0560
(Site). D. R. STRONG Consulting Engineers Inc. (DRS) has prepared this report for the
exclusive use of DRS, the owner, and their agents, for specific application to the
development project as described herein. Use or reliance on this report, or any of its
contents for any revisions of this project, or any other project, or by others not described
above, is forbidden without the expressed permission by DRS.
TASK 1: DEFINE AND MAP STUDY AREA
This Offsite Analysis was prepared in accordance with Core Requirement #2, Section
1.2.2 of the 2009 King County Surface Water Design Manual and City Amendments as
adopted by the City of Renton (Manual). The Site is located at 16433 & 16451 111th
Avenue SE, Renton, Washington. The Project is the subdivision of two parcels into nine
single-family lots.
See Figures 5 through 12 for maps of the study area.
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Level One Downstream Analysis Renton, Washington
TASK 2: RESOURCE REVIEW
• Adopted Basin Plans: The City of Renton and King County Department of Permitting
and Environmental Review (DPER) and Department of Natural Resources and
Parks (DNRP) do not have a specific plan for the East Lake Washington Drainage
Basin.
• Finalized Drainage Studies: No available applicable drainage studies at this time.
• Basin Reconnaissance Summary Reports: None available.
• Comprehensive Plans: Renton’s Comprehensive Plan, adopted on June 22, 2015,
effective July 1, 2015.
• Floodplain/Floodway (FEMA) Map: No floodplains exist on site, See Figure 11.
• Other Offsite Analysis Reports: None available within adjacent properties.
• Sensitive Areas Map Folios, City of Renton GIS: See Figures 6-10. The City’s GIS
system shows a wetland on Site. A Wetland Assessment dated June 2, 2016 was
prepared by Mark Rigos, P.E. This assessment found that there were no areas on
the Site which met the definitions of wetlands.
• DNRP Drainage Complaints and Studies: Per King County Water and Land
Resources Division, there is one complaint within the downstream paths, within
approximately one mile from the Site within the last 10 years. See Figure 12.
• USDA King County Soils Survey: See Figure 4
• King County Wetlands Inventory: Vol. 2 East (1990) – Wetland 5401 (category 2)
identified within one mile of the downstream path. See Figure 8.
• Migrating River Studies: The Site is not located near the channel migration zones of
Cedar River, Tolt River, Raging River, Snoqualmie River, or Green River.
• King County Designated Water Quality Problems: Per the Washington State Water
Quality Assessment 303(d)/305(b) Integrated Report current as of 2012, there are
no water quality problems within 1 mile downstream of the Site.
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Level One Downstream Analysis Renton, Washington
FIGURE 5
CITY OF RENTON TOPOGRAPHY MAP
Site
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FIGURE 6
CITY OF RENTON COAL MINE HAZARD AREAS MAP
Site
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FIGURE 7
CITY OF RENTON FLOOD HAZARDS MAP
Site
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FIGURE 8
CITY OF RENTON STREAMS AND WETLANDS MAP
Site
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FIGURE 9
CITY OF RENTON LANDSLIDE HAZARDS MAP
Site
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FIGURE 10
CITY OF RENTON SEISMIC HAZARD AREAS MAP
Site
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FIGURE 11
FEMA MAP
Site
(Approximate)
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Level One Downstream Analysis Renton, Washington
FIGURE 12
KING COUNTY IMAP DRAINAGE COMPLAINTS MAP
Location Complaint Year Description
A C 2007 Runoff from construction site
Site
A
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TASK 3: FIELD INSPECTION
UPSTREAM TRIBUTARY AREA
Upon evaluation of the upstream area through examining COR topographic map (see
Figure 5) and by conducting field reconnaissance on March 21st 2016, the upstream
tributary area for the Site is considered negligible. The parcels to the north and south
sheet flow to the west, and a swale exists in the right of way of 111th AVE SE,
conveying runoff to the south, away from the site.
GENERAL ONSITE AND OFFSITE DRAINAGE DESCRIPTIONS
The Site is contained within one Threshold Discharge Area (TDA). Runoff from the Site
sheet flows over the west property line and is collected by Big Soos Creek, which is
flowing in a southerly direction. There also exists a Natural Discharge Area (NDA)
which consists of a 12 inch reinforced concrete pipe in the southeastern corner of the
Site which conveys storm water approximately 55 feet before sheet flowing westerly and
converging with Big Soos Creek. The convergence point for the two NDA’s is
approximately 85 feet downstream from the Site. Big Soos Creek is conveyed through a
series of culverts, swales, and as channel flow before discharging into an unnamed
wetland approximately ½ mile downstream.
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TASK 4: DRAINAGE SYSTEM DESCRIPTION AND PROBLEM DESCRIPTIONS
DRAINAGE SYSTEM DESCRIPTION
The downstream analysis is further illustrated and detailed in the Downstream Map
Figure 13 and Downstream Table Figure 14. The drainage area is located within the
East Lake Washington - Renton Drainage Basin. The drainage area was evaluated by
reviewing available resources described in task 2, and by conducting a field
reconnaissance on October 28th, 2016 under overcast conditions.
DOWNSTREAM PATH 1
“A1” is a Natural Discharge Area (NDA) for the Site. It is located along the western
property line (±0).
From Point “A1” to Point “B1”, runoff continues to flow west as sheet flow over till grass.
No concentrated flow was observed (±0’-45’).
Point “B1”, runoff is collected by Big Soos Creek. (±45’).
From Point “B1” to Point “C1”, runoff is conveyed in a southerly direction as channel
flow via Big Soos Creek. Moderate flow was observed (±45’-502’).
Point “C1” is the inlet of a 12” diameter Reinforced Concrete Pipe (RCP). Did not
observe. (±502’).
From Point “C1” to Point “D1”, runoff is conveyed easterly as pipe flow via 12” RCP.
Moderate flow observed (±502’-807’).
Point “D1” is the outlet of a 12” diameter RCP. Moderate flow observed. (±807’).
From Point “D1” to Point “E1”, runoff is conveyed southerly as channel flow via a 2’ tall
and 3’ wide swale. Moderate flow observed (±807’-813’).
Point “E1” is the inlet of a 12” diameter RCP. Moderate flow observed. (±813’).
From Point “E1” to Point “F1”, runoff is conveyed in a southerly direction as pipe flow via
12” RCP culvert. Moderate flow was observed (±813’-835’).
Point “F1” is the outlet of a 12” diameter RCP. Moderate flow observed. (±835’).
From Point “F1” to Point “G1”, runoff is conveyed in a southerly direction as channel
flow via a 2’ tall and 4’ wide swale. Moderate flow was observed. (±835’-925’).
Point “G1” is the inlet of a 12” diameter RCP. Moderate flow observed. (±925’).
From Point “G1” to Point “H1”, runoff is conveyed in a southerly direction as pipe flow
via 12” diameter RCP culvert. Moderate flow was observed (±925’-968’).
Point “H1” is the outlet of a 12” diameter RCP. Moderate flow observed. (±968’).
From Point “H1” to Point “I1”, runoff is conveyed in a southerly direction as channel flow
via a 2’ tall and 4’ wide swale. Moderate flow was observed (±968’-986’).
Point “I1” is the inlet of a 12” diameter RCP. Inlet was partially submerged. (±986’).
From Point “I1” to Point “J1”, runoff is conveyed in an easterly direction as pipe flow via
12” diameter RCP culvert. Heavy flow was observed (±986’-1,022’).
Point “J1” is the outlet of a 12” RCP. Outlet was fully submerged. (±1,022’).
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Level One Downstream Analysis Renton, Washington
From Point “J1” to Point “K1”, runoff is conveyed in a southerly direction as channel flow
via a 2’ tall and 4’ wide swale. Heavy flow was observed (±1,022’-1,037’).
Point “K1” is the inlet of a 24” diameter Corrugated Metal Pipe (CMP) (±1,037’).
From Point “K1” to Point “L1”, runoff is conveyed in a southerly direction as pipe flow via
24” CMP. Moderate flow was observed (±1,037’-1,121’).
Point “L1”, is a Type 1 CB with the outlet of a 24” diameter CMP pipe from the north and
the inlet of a 12” CMP in a southeasterly direction. Facility ID No 180983. Standing
water observed. (±1,121’).
From Point “L1” to Point “M1”, runoff is conveyed in a southeasterly direction as pipe
flow via a 12” diameter CMP. Inlet was observed to be fully submerged. (±1,121’-
1,180’).
Point “M1” is the outlet of a 12” diameter CMP. Not observed. (±1,180’).
From Point “M1” to Point “N1”, runoff is conveyed in a southeasterly direction as
channel flow via Big Soos Creek. Moderate flow was observed. (±1,180’-1,599’). The
downstream path crosses the ¼ mile point during this stretch.
Point “N1” is the inlet of an 18” diameter Corrugated Plastic Pipe (CPP) with a metal
debris barrier. Moderate flow observed (±1,599’).
From Point “N1” to Point “O1”, runoff is conveyed in a southerly direction under SE 168th
Street via an 18” CPP. Moderate flow was observed (±1,599’-1,675’).
Point “O1” is the outlet of an 18” CPP discharging into Big Soos Creek. Moderate flow
observed (±1,675’). The outlet could not be investigated in the field. This is the end of
field investigation.
DOWNSTREAM PATH 2
“A2” is a NDL for the Site. It is located in the southeastern corner of the Site. This NDL
is the inlet of a 12” diameter reinforced concrete pipe conveying storm water in a
southeasterly direction (±0).
From Point “A2” to Point “B2”, runoff continues in a southwesterly direction as pipe flow.
No concentrated flow was observed (±0’-55’).
Point “B2” is the outlet of a 12” reinforced concrete. (±55’).
From Point “B2” to point “C2,” runoff continues in a southwesterly direction as sheet
flow. (±55’-85’).
Point “C2” is Big Soos Creek which collects runoff and is the convergence point of
Downstream Paths 1 and 2. (±85’).
TASK 5: MITIGATION OF EXISTING OR POTENTIAL PROBLEMS
A review of the King County Water and Land Resources Division – Drainage Services
Section Documented Drainage Complaints within one mile of the downstream flow
2016 D. R. STRONG Consulting Engineers Inc. Page 32 Bethany Corner
Level One Downstream Analysis Renton, Washington
paths revealed one complaint within the last ten years and has since been closed.
Several drainage complaints exist within the downstream path but are not within the last
ten years and are not applicable for Level One Downstream Analysis.
The project should not create any problems as specified in Section 1.2.2.1 of the
Manual and therefore is not required to provide Drainage Problem Impact Mitigation
subject to the requirements of Section 1.2.2.2.
A wetvault will provide flow control and basic water quality requirements for the entire
Site. During construction, standard sediment and erosion control methods will be
utilized. This will include the use of a stabilized construction entrance, perimeter silt
fencing, and other necessary measures to minimize soil erosion during construction.
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Level One Downstream Analysis Renton, Washington
FIGURE 13
OFFSITE ANALYSIS DOWNSTREAM MAP
GRAPHIC SCALE
0 100 200 400
1 INCH = 200 FT.
2016 D. R. STRONG Consulting Engineers Inc. Page 34 Bethany Corner
Level One Downstream Analysis Renton, Washington
FIGURE 14
OFFSITE ANALYSIS DOWNSTREAM TABLE
DOWNSTREAM PATH 1
Symbol Drainage
Component Type,
Name, and Size
Drainage Component
Description
Slope Distance
From site
Discharge
Existing
Problems
Potential
Problems
Observations of field inspector
resource reviewer, or resident
See map
Type: sheet flow, swale,
Stream, channel, pipe,
Pond; Size: diameter
Surface area
drainage basin, vegetation, cover,
depth, type of sensitive area, volume
%
1/4 mile =
1,320 feet
Constrictions, under capacity, ponding,
overtopping, flooding, habitat or
organism destruction, scouring, bank
sloughing, sedimentation, incision, other
erosion
Tributary area, likelihood of problem,
overflow pathways, potential impacts.
A1 Natural discharge area Runoff exits at the NDA along the western
property line of the Site.
–0’ None Observed None Anticipated No concentrated flow observed
A1-B1 West sheet flow Sheet flow over till grass None Observed None Anticipated No concentrated flow observed
B1 Stream Big Soos Creek –45’ None Observed None Anticipated Moderate flow observed
B1-C1 Southerly channel flow Big Soos Creek None Observed None Anticipated Moderate flow observed
C1 Pipe inlet 12” diameter Reinforced Concrete Pipe
(RCP)
±502’ Did not observe
C1-D1 Easterly pipe flow 12” diameter RCP. None Observed None Anticipated Moderate flow observed
D1 Pipe outlet 12” diameter RCP ±807’ None Observed None Anticipated Moderate flow observed
D1-E1 Southerly channel flow 2’ tall 3’ wide swale None Observed None Anticipated Moderate flow observed
E1 Pipe inlet 12” diameter RCP ±813’ None Observed None Anticipated Moderate flow observed
E1-F1 Southerly pipe flow 12” diameter RCP None Observed None Anticipated Moderate flow observed
F1 Pipe outlet 12” diameter RCP ±835’ None Observed None Anticipated Moderate flow observed
F1-G1 Southerly channel flow 2’ tall and 4’ wide swale None Observed None Anticipated Moderate flow observed
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G1 Pipe inlet 12” diameter RCP ±925’ None Observed None Anticipated Moderate flow observed
G1-H1 Southerly pipe flow 12” diameter RCP None Observed None Anticipated Moderate flow observed
H1 Pipe outlet 12” diameter RCP ±968’ None Observed None Anticipated Moderate flow observed
H1-I1 Southerly channel flow 2’ tall and 4’ wide swale None Observed None Anticipated Moderate flow observed
I1 Pipe inlet 12” diameter RCP ±986’ Partially
submerged
None Anticipated Heavy flow observed
I1-J1 Easterly pipe flow 12” diameter RCP None Observed None Anticipated Heavy flow observed
J1 Pipe outlet 12” diameter RCP ±1,022’ Fully submerged None Anticipated Heavy flow observed
J1-K1 Southerly channel flow 2’ tall 4’ wide swale None Observed None Anticipated Heavily vegetated - moderate flow
observed
K1 Pipe inlet 24” diameter Corrugated Metal Pipe
(CMP)
±1,037’ None Observed None Anticipated Moderate flow observed
K1-L1 Southerly pipe flow 24” diameter CMP None Observed None Anticipated Moderate flow observed
L1 Type 1 CB Renton Facility No. 180983 ±1,121’ None Observed None Anticipated Standing water observed
L1-M1 Southeasterly pipe 12” diameter CMP Fully submerged None Anticipated Heavy flow observed
M1 Pipe outlet 12” diameter CMP ±1,180’ None Observed None Anticipated Moderate flow observed
M1-N1 Southeasterly channel
flow
Big Soos Creek None Observed None Anticipated Moderate flow observed
N1 Pipe inlet 18” diameter corrugated plastic pipe
(CPP) under SE 168th Street
±1,599’ None Observed None Anticipated Moderate flow observed. Metal debris
barrier covering inlet
N1-O1 Southerly pipe flow 18” diameter CPP None Observed None Anticipated Moderate flow observed
O1 Pipe outlet 18” diameter CPP. Discharging into Big
Soos Creek
±1,675’ None Observed None Anticipated Discharge point not observed
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Level One Downstream Analysis Renton, Washington
DOWNSTREAM PATH 2
Symbol Drainage
Component Type,
Name, and Size
Drainage Component
Description
Slope Distance
From site
Discharge
Existing
Problems
Potential
Problems
Observations of field inspector
resource reviewer, or resident
See map
Type: sheet flow, swale,
Stream, channel, pipe,
Pond; Size: diameter
Surface area
drainage basin, vegetation, cover,
depth, type of sensitive area, volume
%
1/4 mile =
1,320 feet
Constrictions, under capacity, ponding,
overtopping, flooding, habitat or
organism destruction, scouring, bank
sloughing, sedimentation, incision, other
erosion
Tributary area, likelihood of problem,
overflow pathways, potential impacts.
A2 Natural discharge area –
Pipe inlet
12” diameter RCP. –0’ None Observed None Anticipated No concentrated flow observed
A2-B2 Southwesterly pipe flow 12” diameter RCP None Observed None Anticipated No concentrated flow observed
B2 Pipe outlet 12” diameter RCP –55’ None Observed None Anticipated No concentrated flow observed
B2-C2 Southwesterly sheet flow Sheet flow over moderately vegetated
areas
None Observed None Anticipated Moderate flow observed
C2 Stream Big Soos Creek. Convergence point of
Downstream Paths 1 and 2
±85’ Did not observe
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Technical Information Report Renton, Washington
SECTION IV
FLOW CONTROL ANALYSIS AND WATER QUALITY DESIGN
EXISTING SITE HYDROLOGY
KCRTS was used to model runoff from the Site. The Site falls within the City’s Flow
Control Duration Standard – Matching Forested area. The Site was modeled as
predeveloped forested condtions for target surfaces and impervious for flow-through
surfaces (see Figure 15). Results of the KCRTS analysis are included in this section.
Modeling Input for the Pre-developed Site
Modeling Results
Flow Frequency Analysis
Time Series File:predev.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) Period
0.131 2 2/09/01 18:00 0.176 1 100.00 0.990
0.042 7 1/05/02 16:00 0.131 2 25.00 0.960
0.103 3 2/28/03 3:00 0.103 3 10.00 0.900
0.012 8 8/26/04 2:00 0.103 4 5.00 0.800
0.061 6 1/05/05 8:00 0.091 5 3.00 0.667
0.103 4 1/18/06 20:00 0.061 6 2.00 0.500
0.091 5 11/24/06 4:00 0.042 7 1.30 0.231
0.176 1 1/09/08 9:00 0.012 8 1.10 0.091
Computed Peaks 0.161 50.00 0.980
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Technical Information Report Renton, Washington
FIGURE 15
PREDEVELOPED AREA MAP
GRAPHIC SCALE
0 20 40 60
1 INCH = 40 FT.
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Technical Information Report Renton, Washington
DEVELOPED SITE HYDROLOGY
Soil Type
The soil types are unchanged from predeveloped conditions.
Land Cover
KCRTS was used to model the developed peak runoff from the Site. The portions of the
Site within the developable area tributary to the proposed detention facility were
modeled as “Till Grass”, and Impervious as appropriate. Results of the KCRTS analysis
are included in this section.
Modeling Input for RDIN Site
Modeling Results
Flow Frequency Analysis
Time Series File:rdin.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) Period
0.345 6 2/09/01 2:00 0.697 1 100.00 0.990
0.281 8 1/05/02 16:00 0.443 2 25.00 0.960
0.414 3 2/27/03 7:00 0.414 3 10.00 0.900
0.305 7 8/26/04 2:00 0.367 4 5.00 0.800
0.367 4 10/28/04 16:00 0.366 5 3.00 0.667
0.366 5 1/18/06 16:00 0.345 6 2.00 0.500
0.443 2 10/26/06 0:00 0.305 7 1.30 0.231
0.697 1 1/09/08 6:00 0.281 8 1.10 0.091
Computed Peaks 0.612 50.00 0.980
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Technical Information Report Renton, Washington
Modeling Input for the Bypass
.
Modeling Results
Flow Frequency Analysis
Time Series File:byp.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) Period
0.015 4 2/09/01 2:00 0.035 1 100.00 0.990
0.009 6 1/05/02 16:00 0.019 2 25.00 0.960
0.019 2 2/27/03 7:00 0.016 3 10.00 0.900
0.005 8 8/26/04 2:00 0.015 4 5.00 0.800
0.009 7 1/05/05 8:00 0.014 5 3.00 0.667
0.016 3 1/18/06 16:00 0.009 6 2.00 0.500
0.014 5 11/24/06 3:00 0.009 7 1.30 0.231
0.035 1 1/09/08 6:00 0.005 8 1.10 0.091
Computed Peaks 0.029 50.00 0.980
2016 D. R. STRONG Consulting Engineers Inc. Page 41 Bethany Corner
Technical Information Report Renton, Washington
FIGURE 16
DEVELOPED AREA MAP
GRAPHIC SCALE
0 20 40 60
1 INCH = 40 FT.
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Technical Information Report Renton, Washington
PERFORMANCE STANDARDS
The Site is required to adhere to Flow Control Duration Standard – Matching Forested
site conditions of the existing site (reference 11-A of COR 2009 Surface Water Design
Manual Amendment). A wet-vault will provide flow control and basic water quality
treatment. The Project is required to “match the flow duration of pre-developed rates for
forested (historic) site conditions over the range of flows extending from 50% of 2-year
up to the full 50-year flow.” (2009 Surface Water Design Manual Amendment, Sec.
1.2.3.1).
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Technical Information Report Renton, Washington
FLOW CONTROL SYSTEM
The Project will utilize an detention facility designed to control site runoff. The King
County Runoff Time Series (KCRTS) software was used to size the facility. The
detention pond design information is included in this section.
Retention/Detention Facility
Type of Facility: Detention Vault
Facility Length: 96.00 ft
Facility Width: 46.00 ft
Facility Area: 4416. sq. ft
Effective Storage Depth: 5.00 ft
Stage 0 Elevation: 0.00 ft
Storage Volume: 22080. cu. ft
Riser Head: 5.00 ft
Riser Diameter: 12.00 inches
Number of orifices: 2
Full Head Pipe
Orifice # Height Diameter Discharge Diameter
(ft) (in) (CFS) (in)
1 0.00 0.75 0.034
2 3.23 1.38 0.068 4.0
Top Notch Weir: None
Outflow Rating Curve: None
Stage Elevation Storage Discharge Percolation
(ft) (ft) (cu. ft) (ac-ft) (cfs) (cfs)
0.00 0.00 0. 0.000 0.000 0.00
0.01 0.01 44. 0.001 0.001 0.00
0.02 0.02 88. 0.002 0.002 0.00
0.03 0.03 133. 0.003 0.003 0.00
0.04 0.04 177. 0.004 0.003 0.00
0.05 0.05 221. 0.005 0.004 0.00
0.06 0.06 265. 0.006 0.004 0.00
0.16 0.16 707. 0.016 0.006 0.00
0.26 0.26 1148. 0.026 0.008 0.00
0.36 0.36 1590. 0.036 0.009 0.00
0.46 0.46 2031. 0.047 0.010 0.00
0.56 0.56 2473. 0.057 0.011 0.00
0.66 0.66 2915. 0.067 0.012 0.00
0.76 0.76 3356. 0.077 0.013 0.00
0.86 0.86 3798. 0.087 0.014 0.00
0.96 0.96 4239. 0.097 0.015 0.00
1.06 1.06 4681. 0.107 0.016 0.00
1.16 1.16 5123. 0.118 0.016 0.00
1.26 1.26 5564. 0.128 0.017 0.00
1.36 1.36 6006. 0.138 0.018 0.00
1.46 1.46 6447. 0.148 0.018 0.00
1.56 1.56 6889. 0.158 0.019 0.00
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1.66 1.66 7331. 0.168 0.020 0.00
1.76 1.76 7772. 0.178 0.020 0.00
1.86 1.86 8214. 0.189 0.021 0.00
1.96 1.96 8655. 0.199 0.021 0.00
2.06 2.06 9097. 0.209 0.022 0.00
2.16 2.16 9539. 0.219 0.022 0.00
2.26 2.26 9980. 0.229 0.023 0.00
2.36 2.36 10422. 0.239 0.023 0.00
2.46 2.46 10863. 0.249 0.024 0.00
2.56 2.56 11305. 0.260 0.024 0.00
2.66 2.66 11747. 0.270 0.025 0.00
2.76 2.76 12188. 0.280 0.025 0.00
2.86 2.86 12630. 0.290 0.026 0.00
2.96 2.96 13071. 0.300 0.026 0.00
3.06 3.06 13513. 0.310 0.027 0.00
3.16 3.16 13955. 0.320 0.027 0.00
3.23 3.23 14264. 0.327 0.027 0.00
3.24 3.24 14308. 0.328 0.028 0.00
3.26 3.26 14396. 0.330 0.029 0.00
3.27 3.27 14440. 0.332 0.031 0.00
3.29 3.29 14529. 0.334 0.034 0.00
3.30 3.30 14573. 0.335 0.037 0.00
3.32 3.32 14661. 0.337 0.042 0.00
3.33 3.33 14705. 0.338 0.044 0.00
3.34 3.34 14749. 0.339 0.045 0.00
3.44 3.44 15191. 0.349 0.052 0.00
3.54 3.54 15633. 0.359 0.057 0.00
3.64 3.64 16074. 0.369 0.062 0.00
3.74 3.74 16516. 0.379 0.066 0.00
3.84 3.84 16957. 0.389 0.070 0.00
3.94 3.94 17399. 0.399 0.074 0.00
4.04 4.04 17841. 0.410 0.077 0.00
4.14 4.14 18282. 0.420 0.080 0.00
4.24 4.24 18724. 0.430 0.083 0.00
4.34 4.34 19165. 0.440 0.086 0.00
4.44 4.44 19607. 0.450 0.089 0.00
4.54 4.54 20049. 0.460 0.091 0.00
4.64 4.64 20490. 0.470 0.094 0.00
4.74 4.74 20932. 0.481 0.096 0.00
4.84 4.84 21373. 0.491 0.099 0.00
4.94 4.94 21815. 0.501 0.101 0.00
5.00 5.00 22080. 0.507 0.102 0.00
5.10 5.10 22522. 0.517 0.413 0.00
5.20 5.20 22963. 0.527 0.978 0.00
5.30 5.30 23405. 0.537 1.710 0.00
5.40 5.40 23846. 0.547 2.500 0.00
5.50 5.50 24288. 0.558 2.790 0.00
5.60 5.60 24730. 0.568 3.040 0.00
5.70 5.70 25171. 0.578 3.280 0.00
5.80 5.80 25613. 0.588 3.500 0.00
5.90 5.90 26054. 0.598 3.710 0.00
6.00 6.00 26496. 0.608 3.900 0.00
6.10 6.10 26938. 0.618 4.090 0.00
6.20 6.20 27379. 0.629 4.270 0.00
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Technical Information Report Renton, Washington
6.30 6.30 27821. 0.639 4.440 0.00
6.40 6.40 28262. 0.649 4.600 0.00
6.50 6.50 28704. 0.659 4.760 0.00
6.60 6.60 29146. 0.669 4.920 0.00
6.70 6.70 29587. 0.679 5.070 0.00
6.80 6.80 30029. 0.689 5.210 0.00
6.90 6.90 30470. 0.700 5.350 0.00
7.00 7.00 30912. 0.710 5.490 0.00
Hyd Inflow Outflow Peak Storage
Stage Elev (Cu-Ft) (Ac-Ft)
1 0.70 0.45 5.11 5.11 22547. 0.518
2 0.34 0.12 5.01 5.01 22113. 0.508
3 0.44 0.09 4.35 4.35 19193. 0.441
4 0.41 0.08 4.30 4.30 19003. 0.436
5 0.37 0.06 3.60 3.60 15883. 0.365
6 0.37 0.03 3.14 3.14 13862. 0.318
7 0.28 0.03 2.79 2.79 12313. 0.283
8 0.30 0.02 1.95 1.95 8624. 0.198
Hyd R/D Facility Tributary Reservoir POC Outflow
Outflow Inflow Inflow Target Calc
1 0.45 0.03 ******** ******* 0.46
2 0.12 0.02 ******** 0.13 0.14
3 0.09 0.01 ******** ******* 0.09
4 0.08 0.02 ******** ******* 0.09
5 0.06 0.02 ******** ******* 0.07
6 0.03 0.01 ******** ******* 0.03
7 0.03 0.01 ******** ******* 0.03
8 0.02 0.01 ******** ******* 0.02
----------------------------------
Route Time Series through Facility
Inflow Time Series File:rdin.tsf
Outflow Time Series File:rdout
POC Time Series File:dsout
Inflow/Outflow Analysis
Peak Inflow Discharge: 0.697 CFS at 6:00 on Jan 9 in Year 8
Peak Outflow Discharge: 0.445 CFS at 10:00 on Jan 9 in Year 8
Peak Reservoir Stage: 5.11 Ft
Peak Reservoir Elev: 5.11 Ft
Peak Reservoir Storage: 22547. Cu-Ft
: 0.518 Ac-Ft
Add Time Series:byp.tsf
Peak Summed Discharge: 0.456 CFS at 10:00 on Jan 9 in Year 8
Point of Compliance File:dsout.tsf
Flow Frequency Analysis
Time Series File:rdout.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
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Technical Information Report Renton, Washington
(CFS) (CFS) (ft) Period
0.125 2 2/09/01 20:00 0.445 5.11 1 100.00 0.990
0.025 7 1/07/02 4:00 0.125 5.01 2 25.00 0.960
0.085 4 3/06/03 22:00 0.086 4.35 3 10.00 0.900
0.021 8 8/26/04 7:00 0.085 4.30 4 5.00 0.800
0.027 6 1/08/05 5:00 0.060 3.60 5 3.00 0.667
0.060 5 1/19/06 0:00 0.027 3.14 6 2.00 0.500
0.086 3 11/24/06 8:00 0.025 2.79 7 1.30 0.231
0.445 1 1/09/08 10:00 0.021 1.95 8 1.10 0.091
Computed Peaks 0.338 5.08 50.00 0.980
Flow Frequency Analysis
Time Series File:dsout.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) Period
0.135 2 2/09/01 20:00 0.456 1 100.00 0.990
0.030 7 1/05/02 16:00 0.135 2 25.00 0.960
0.092 4 3/06/03 21:00 0.095 3 10.00 0.900
0.024 8 8/26/04 2:00 0.092 4 5.00 0.800
0.032 6 1/05/05 8:00 0.068 5 3.00 0.667
0.068 5 1/19/06 0:00 0.032 6 2.00 0.500
0.095 3 11/24/06 7:00 0.030 7 1.30 0.231
0.456 1 1/09/08 10:00 0.024 8 1.10 0.091
Computed Peaks 0.349 50.00 0.980
Flow Duration from Time Series File:rdout.tsf
Cutoff Count Frequency CDF Exceedence_Probability
CFS % % %
0.002 31735 51.753 51.753 48.247 0.482E+00
0.005 6972 11.370 63.123 36.877 0.369E+00
0.009 6435 10.494 73.617 26.383 0.264E+00
0.012 6038 9.847 83.464 16.536 0.165E+00
0.016 3952 6.445 89.909 10.091 0.101E+00
0.019 2518 4.106 94.015 5.985 0.598E-01
0.023 1795 2.927 96.942 3.058 0.306E-01
0.026 1321 2.154 99.097 0.903 0.903E-02
0.030 257 0.419 99.516 0.484 0.484E-02
0.033 19 0.031 99.547 0.453 0.453E-02
0.037 14 0.023 99.569 0.431 0.431E-02
0.040 11 0.018 99.587 0.413 0.413E-02
0.044 12 0.020 99.607 0.393 0.393E-02
0.047 22 0.036 99.643 0.357 0.357E-02
0.051 24 0.039 99.682 0.318 0.318E-02
0.054 26 0.042 99.724 0.276 0.276E-02
0.058 23 0.038 99.762 0.238 0.238E-02
0.061 25 0.041 99.803 0.197 0.197E-02
0.065 14 0.023 99.826 0.174 0.174E-02
0.068 10 0.016 99.842 0.158 0.158E-02
0.072 13 0.021 99.863 0.137 0.137E-02
0.075 12 0.020 99.883 0.117 0.117E-02
0.079 10 0.016 99.899 0.101 0.101E-02
0.082 12 0.020 99.918 0.082 0.815E-03
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0.086 16 0.026 99.945 0.055 0.554E-03
0.089 12 0.020 99.964 0.036 0.359E-03
0.093 7 0.011 99.976 0.024 0.245E-03
0.096 4 0.007 99.982 0.018 0.179E-03
0.100 5 0.008 99.990 0.010 0.978E-04
0.103 5 0.008 99.998 0.002 0.163E-04
0.107 0 0.000 99.998 0.002 0.163E-04
0.110 0 0.000 99.998 0.002 0.163E-04
0.114 0 0.000 99.998 0.002 0.163E-04
0.117 0 0.000 99.998 0.002 0.163E-04
0.121 0 0.000 99.998 0.002 0.163E-04
0.124 0 0.000 99.998 0.002 0.163E-04
Flow Duration from Time Series File:dsout.tsf
Cutoff Count Frequency CDF Exceedence_Probability
CFS % % %
0.002 31731 51.747 51.747 48.253 0.483E+00
0.006 7398 12.065 63.811 36.189 0.362E+00
0.009 6714 10.949 74.760 25.240 0.252E+00
0.013 5830 9.508 84.268 15.732 0.157E+00
0.017 4128 6.732 91.000 9.000 0.900E-01
0.021 2134 3.480 94.480 5.520 0.552E-01
0.025 1584 2.583 97.063 2.937 0.294E-01
0.028 1048 1.709 98.772 1.228 0.123E-01
0.032 425 0.693 99.465 0.535 0.535E-02
0.036 39 0.064 99.529 0.471 0.471E-02
0.040 20 0.033 99.561 0.439 0.439E-02
0.043 16 0.026 99.587 0.413 0.413E-02
0.047 14 0.023 99.610 0.390 0.390E-02
0.051 20 0.033 99.643 0.357 0.357E-02
0.055 23 0.038 99.680 0.320 0.320E-02
0.059 26 0.042 99.723 0.277 0.277E-02
0.062 15 0.024 99.747 0.253 0.253E-02
0.066 26 0.042 99.790 0.210 0.210E-02
0.070 23 0.038 99.827 0.173 0.173E-02
0.074 9 0.015 99.842 0.158 0.158E-02
0.078 12 0.020 99.861 0.139 0.139E-02
0.081 12 0.020 99.881 0.119 0.119E-02
0.085 9 0.015 99.896 0.104 0.104E-02
0.089 11 0.018 99.914 0.086 0.864E-03
0.093 19 0.031 99.945 0.055 0.554E-03
0.096 14 0.023 99.967 0.033 0.326E-03
0.100 3 0.005 99.972 0.028 0.277E-03
0.104 4 0.007 99.979 0.021 0.212E-03
0.108 4 0.007 99.985 0.015 0.147E-03
0.112 5 0.008 99.993 0.007 0.652E-04
0.115 3 0.005 99.998 0.002 0.163E-04
0.119 0 0.000 99.998 0.002 0.163E-04
0.123 0 0.000 99.998 0.002 0.163E-04
0.127 0 0.000 99.998 0.002 0.163E-04
0.130 0 0.000 99.998 0.002 0.163E-04
0.134 0 0.000 99.998 0.002 0.163E-04
Duration Comparison Anaylsis
Base File: predev.tsf
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New File: dsout.tsf
Cutoff Units: Discharge in CFS
-----Fraction of Time----- ---------Check of Tolerance-------
Cutoff Base New %Change Probability Base New %Change
0.030 | 0.85E-02 0.65E-02 -23.1 | 0.85E-02 0.030 0.029 -3.3
0.038 | 0.59E-02 0.45E-02 -24.0 | 0.59E-02 0.038 0.031 -18.7
0.046 | 0.47E-02 0.40E-02 -14.7 | 0.47E-02 0.046 0.036 -20.8
0.053 | 0.34E-02 0.34E-02 -2.4 | 0.34E-02 0.053 0.053 -1.4
0.061 | 0.26E-02 0.26E-02 0.0 | 0.26E-02 0.061 0.061 0.0
0.069 | 0.20E-02 0.18E-02 -7.4 | 0.20E-02 0.069 0.067 -2.2
0.076 | 0.13E-02 0.14E-02 10.0 | 0.13E-02 0.076 0.079 3.6
0.084 | 0.95E-03 0.11E-02 13.8 | 0.95E-03 0.084 0.087 3.7
0.092 | 0.57E-03 0.65E-03 14.3 | 0.57E-03 0.092 0.093 0.7
0.100 | 0.34E-03 0.29E-03 -14.3 | 0.34E-03 0.100 0.096 -3.4
0.107 | 0.18E-03 0.15E-03 -18.2 | 0.18E-03 0.107 0.106 -0.9
0.115 | 0.13E-03 0.16E-04 -87.5 | 0.13E-03 0.115 0.108 -5.6
0.123 | 0.82E-04 0.16E-04 -80.0 | 0.82E-04 0.123 0.111 -9.4
0.130 | 0.16E-04 0.16E-04 0.0 | 0.16E-04 0.130 0.135 3.7
Maximum positive excursion = 0.005 cfs ( 5.7%)
occurring at 0.080 cfs on the Base Data:predev.tsf
and at 0.085 cfs on the New Data:dsout.tsf
Maximum negative excursion = 0.010 cfs (-21.7%)
occurring at 0.044 cfs on the Base Data:predev.tsf
and at 0.035 cfs on the New Data:dsout.tsf
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Flow Frequency
Duration Analysis
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WATER QUALITY TREATMENT SYSTEM
The Project is required to adhere to the City of Renton’s Basic Water Quality treatment
criteria. A combined detention/water quality vault located within Tract A is proposed to
accommodate this requirement.
Sizing for a wetvault was calculated from the formula provided by Section 6.4.1.1
Methods of Analysis of the Manual. The minimum wetpool volume required is 6,262
cubic feet. The Project will provide 11,333 cubic feet of dead storage. The wetvault will
occupy the eastern half of the detention vault. The vault geometry provides a length to
width ratio of 4.33 : 1 so a removable baffle will be provided as shown on the plans.
BASIC WETVAULT ANALYSIS
As required per Section 6.4.1.1 2009 King County
Step 1: Identify required water quality facility volume factor ("f")
f=3 (basic wetpond volume factor)
Step 2: Determine rainfall (R) for the mean annual storm per Fig. 6.4.1.A
R=0.47 in.
Step 3: Calculate runoff from the mean annual storm (Vr) for the developed site.
Vr =(0.9Ai + 0.25Atg + 0.10Atf + 0.01Ao) x R/12 where . . .
Vr =volume of runoff from mean annual storm (c.f.)
Ai=area of impervious surface (s.f.)
Atg=area of till soil covered with grass (s.f.)
Atf=area of till soil covered with till forest (s.f.)
Ao=area of outwash soil covered with grass or forest (s.f.)
R=rainfall from mean annual storm (in.)
Ai=50,896 s.f.
Atg=29,953 s.f.
Atf=- s.f.
Ao=0 s.f.
R =0.47 in.
Vr =2,087 c.f.
Step 4: Calculate water quality volume (Vb).
Vb=f x Vr where . . .
Vb=water quality volume (cf)
f=volume factor from Step 1
Vr =runoff volume from Step 3
Vb=6,262 c.f. (minimum wetpool volume required)
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FIGURE 17
DETENTION & WATER QUALITY FACILITY DETAILS
BY:Date:
RECOMMENDED FOR APPOVAL
BY:
BY:
BY:
Date:
Date:
Date:
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SECTION V
CONVEYANCE SYSTEM ANALYSIS AND DESIGN
Per Core Requirement #4 of the KCSWDM, the conveyance system must be analyzed
and designed for the existing tributary and developed onsite runoff. Pipe systems shall
be designed to convey the 25-year storm with a minimum of 6-inches of freeboard
between the design water surface and structure grate. Any overflow from the 100-year
design storm must not create or aggravate a severe flooding problem. The Rational
Method will be used to calculate the Q-Ratio for each pipe node.
A conveyance system consisting primarily of pipes and catch basins will be designed for
the Project. Onsite runoff will be collected by the multiple catch basins. Pipes are
typically six-inch to twelve-inch diameter LCPE material.
Per Figures 3.2.1.C and 3.2.1.D in the 2009 Manual the 24-hour precipitation in inches
is 3.4 and 3.9 for the 25-year and 100-year storms respectively.
In all cases the 25-year storm was conveyed with at least 6-inches of freeboard. There
were no overflows as a result of the 100-year storm.
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BACKWATER ANALYSIS
Path:R:\2016\0\16062\3\Documents\Analysis\KCBW\161212\BACKWATER-16062_25.xls
Storm Water Runoff Variables:
A=Total of Subasin and Tributary Areas
C=Runoff Coefficient (the anticipated proportion of rainfall volume that runs off the area) see '09 KCSWM Table 3.2.1A
CC=Composite Runoff Coefficient
CC=S(Cn*An)/ATotal
Tc=Time of Concentration (Typically 6.3 minutes which is the minimum value used in calculations)
R=design return frequency
iR=Unit peak rainfall intensity factor
iR=(aR)(Tc)^(-bR)
aR,bR=coefficients from '09 KCSWM Table 3.2.1.B used to adjust the equation for the design storm
IR=Peak rainfall intensity factor for a storm of return frequency 'R'
IR=PR*iR
PR=total precipitation (inches) for the 24-hour storm event for the given frequency. See Issopluvial Maps in '09 KCSWM Figures 3.2.1.D
QR=peak flow (cfs) for a storm of return frequency 'R'
QR=CC*iR*A
The Q-Ratio describes the ratio of the tributary flow to the main upstream flow.
R=25 -year storm
aR=2.66
bR=0.65
PR=3.4 inches
Conveyance System Variables:
d=pipe diameter
n=Manning's Number
l=length of pipe
Pipe Structures Subasins &A A C CC Tc iR IR QR SQR Q - d Material n l Slope invert invert over-Q V Bend CB
Tributaries subasin Ratio in out flow Full Full Dia
elev.Flow Flow
FROM CB To CB sf Ac Ac Min.cfs cfs in ft %ft ft ft cfs fps
CB-8 TO INLET 2
P-8 8 7 8 10226 0.23 0.58 6.3 0.80 2.73 0.37 0.37 0.00 12 N-12 0.012 82 7.01 425.15 419.40 428.40 10.25 13.05 90 2
FROM RUN 9-7 1957 0.04 0.90
P-7 7 INLET 2 7 794 0.02 0.90
P-7 7 INLET 2 7 2751 0.06 0.90 6.3 0.80 2.73 0.16 0.53 0.30 12 N-12 0.012 24 12.08 419.40 416.50 426.65 13.45 17.13 0 4
12977 0.30 0.64
CB-6 TO INLET 1
P-6 6 5 6 30608 0.70 0.59 6.3 0.80 2.73 1.14 1.14 0.00 12 N-12 0.012 25 1.00 421.66 421.41 424.91 3.87 4.93 90 2
P-5 5 4 5 28631 0.66 0.59 6.3 0.80 2.73 1.05 2.19 0.48 12 N-12 0.012 106 1.00 421.41 420.35 424.91 3.87 4.93 90 2
P-4 4 INLET 1 4 785 0.02 0.90 6.3 0.80 2.73 0.04 2.23 0.02 12 N-12 0.012 25 15.40 420.35 416.50 426.64 15.19 19.34 0 4
60024 1.38 0.59
CB-11 TO CB-1
P-12 12 11 12 6600 0.15 0.90 6.3 0.80 2.73 0.37 0.37 0.00 12 N-12 0.012 132 4.46 430.59 424.70 433.42 8.18 10.41 0 2
P-11 11 10 11 0 0.00 0.90 6.3 0.80 2.73 0.00 0.37 0.00 12 N-12 0.012 151 2.93 424.70 420.28 428.40 6.62 8.43 49 2
P-10 10 3 10 0 0.00 0.90 6.3 0.80 2.73 0.00 0.37 0.00 12 N-12 0.012 11 17.73 420.28 418.33 425.28 16.29 20.75 49 2
P-3 3 2 3 485 0.01 0.90 6.3 0.80 2.73 0.47 0.85 1.27 12 N-12 0.012 134 0.80 418.33 417.26 424.41 3.46 4.40 64 4
P-2 2 1 2 0 0.00 0.90 6.3 0.80 2.73 0.00 0.85 0.00 12 N-12 0.012 8 1.00 417.26 417.18 419.88 3.87 4.93 68 2
7085 0.16 0.90
CB-9 TO CB-7
P-9 9 7 9 1957 0.04 0.90 6.3 0.80 2.73 0.11 0.11 0.00 12 N-12 0.012 73 3.42 421.90 419.40 424.90 7.16 9.12 90 2
Path:R:\2016\0\16062\3\Documents\Analysis\KCBW\161212\BACKWATER-16062_100.xls
Storm Water Runoff Variables:
A=Total of Subasin and Tributary Areas
C=Runoff Coefficient (the anticipated proportion of rainfall volume that runs off the area) see '09 KCSWM Table 3.2.1A
CC=Composite Runoff Coefficient
CC=S(Cn*An)/ATotal
Tc=Time of Concentration (Typically 6.3 minutes which is the minimum value used in calculations)
R=design return frequency
iR=Unit peak rainfall intensity factor
iR=(aR)(Tc)^(-bR)
aR,bR=coefficients from '09 KCSWM Table 3.2.1.B used to adjust the equation for the design storm
IR=Peak rainfall intensity factor for a storm of return frequency 'R'
IR=PR*iR
PR=total precipitation (inches) for the 24-hour storm event for the given frequency. See Issopluvial Maps in '09 KCSWM Figures 3.2.1.D
QR=peak flow (cfs) for a storm of return frequency 'R'
QR=CC*iR*A
The Q-Ratio describes the ratio of the tributary flow to the main upstream flow.
R=100 -year storm
aR=2.61
bR=0.63
PR=3.9 inches
Conveyance System Variables:
d=pipe diameter
n=Manning's Number
l=length of pipe
Pipe Structures Subasins &A A C CC Tc iR IR QR SQR Q - d Material n l Slope invert invert over-Q V Bend CB
Tributaries subasin Ratio in out flow Full Full Dia
elev.Flow Flow
FROM CB To CB sf Ac Ac Min.cfs cfs in ft %ft ft ft cfs fps
CB-8 TO INLET 2
P-8 8 7 8 10226 0.23 0.58 6.3 0.82 3.19 0.43 0.43 0.00 12 N-12 0.012 82 7.01 425.15 419.40 428.40 10.25 13.05 90 2
FROM RUN 9-7 1957 0.04 0.90
P-7 7 INLET 2 7 794 0.02 0.90
P-7 7 INLET 2 7 2751 0.06 0.90 6.3 0.82 3.19 0.18 0.61 0.30 12 N-12 0.012 24 12.08 419.40 416.50 426.65 13.45 17.13 0 4
12977 0.30 0.64
CB-6 TO INLET 1
P-6 6 5 6 30608 0.70 0.59 6.3 0.82 3.19 1.33 1.33 0.00 12 N-12 0.012 25 1.00 421.66 421.41 424.91 3.87 4.93 90 2
P-5 5 4 5 28631 0.66 0.59 6.3 0.82 3.19 1.23 2.56 0.48 12 N-12 0.012 106 1.00 421.41 420.35 424.91 3.87 4.93 90 2
P-4 4 INLET 1 4 785 0.02 0.90 6.3 0.82 3.19 0.05 2.61 0.02 12 N-12 0.012 25 15.40 420.35 416.50 426.64 15.19 19.34 0 4
60024 1.38 0.59
CB-11 TO CB-1
P-12 12 11 12 6600 0.15 0.90 6.3 0.82 3.19 0.44 0.44 0.00 12 N-12 0.012 132 4.46 430.59 424.70 433.42 8.18 10.41 0 2
P-11 11 10 11 0 0.00 0.90 6.3 0.82 3.19 0.00 0.44 0.00 12 N-12 0.012 151 2.93 424.70 420.28 428.40 6.62 8.43 49 2
P-10 10 3 10 0 0.00 0.90 6.3 0.82 3.19 0.00 0.44 0.00 12 N-12 0.012 11 17.73 420.28 418.33 425.28 16.29 20.75 49 2
P-3 3 2 3 485 0.01 0.90 6.3 0.82 3.19 0.48 0.91 1.10 12 N-12 0.012 134 0.80 418.33 417.26 424.41 3.46 4.40 64 4
P-2 2 1 2 0 0.00 0.90 6.3 0.82 3.19 0.00 0.91 0.00 12 N-12 0.012 8 1.00 417.26 417.18 419.88 3.87 4.93 68 2
7085 0.16 0.90
CB-9 TO CB-7
P-9 9 7 9 1957 0.04 0.90 6.3 0.82 3.19 0.13 0.13 0.00 12 N-12 0.012 73 3.42 421.90 419.40 424.90 7.16 9.12 90 2
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FIGURE 18
BACKWATER ANALYSIS MAP
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BACKWATER ANALYSIS RESULTS
BACKWATER COMPUTER PROGRAM FOR PIPES
Pipe data from file:CB-6 TO INLET 1.bwp
Surcharge condition at intermediate junctions
Tailwater Elevation:423.61 feet
Discharge Range:2.11 to 2.61 Step of 0.1 [cfs]
Overflow Elevation:424.91 feet
Weir:NONE
Upstream Velocity:0. feet/sec
PIPE NO. 1: 25 LF - 12"CP @ 15.40% OUTLET: 416.50 INLET: 420.35 INTYP: 5
JUNC NO. 1: OVERFLOW-EL: 426.64 BEND: 0 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.02
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
*******************************************************************************
2.11 3.40 423.75 * 0.012 0.63 0.26 7.11 7.11 3.34 3.40 0.77
2.21 3.41 423.76 * 0.012 0.64 0.26 7.11 7.11 3.34 3.41 0.80
2.31 3.43 423.78 * 0.012 0.66 0.27 7.11 7.11 3.35 3.43 0.82
2.41 3.44 423.79 * 0.012 0.67 0.27 7.11 7.11 3.36 3.44 0.84
2.51 3.46 423.81 * 0.012 0.68 0.28 7.11 7.11 3.37 3.46 0.86
2.61 3.47 423.82 * 0.012 0.70 0.29 7.11 7.11 3.37 3.47 0.88
2.61 3.47 423.82 * 0.012 0.70 0.29 7.11 7.11 3.37 3.47 0.88
PIPE NO. 2: 106 LF - 12"CP @ 1.00% OUTLET: 420.35 INLET: 421.41 INTYP: 5
JUNC NO. 2: OVERFLOW-EL: 424.91 BEND: 90 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.48
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
*******************************************************************************
2.07 2.84 424.25 * 0.012 0.62 0.53 3.40 3.40 2.65 2.84 0.97
2.17 2.90 424.31 * 0.012 0.63 0.54 3.41 3.41 2.69 2.90 1.00
2.27 2.96 424.37 * 0.012 0.65 0.56 3.43 3.43 2.73 2.96 1.04
2.36 3.03 424.44 * 0.012 0.66 0.57 3.44 3.44 2.78 3.03 1.07
2.46 3.10 424.51 * 0.012 0.68 0.59 3.46 3.46 2.83 3.10 1.11
2.56 3.17 424.58 * 0.012 0.69 0.60 3.47 3.47 2.88 3.17 1.14
2.56 3.17 424.58 * 0.012 0.69 0.60 3.47 3.47 2.88 3.17 1.14
PIPE NO. 3: 25 LF - 12"CP @ 1.00% OUTLET: 421.41 INLET: 421.66 INTYP: 5
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
*******************************************************************************
1.40 2.70 424.36 * 0.012 0.51 0.42 2.84 2.84 2.63 2.70 0.72
1.46 2.77 424.43 * 0.012 0.52 0.43 2.90 2.90 2.68 2.77 0.74
1.53 2.84 424.50 * 0.012 0.53 0.44 2.96 2.96 2.75 2.84 0.77
1.60 2.92 424.58 * 0.012 0.54 0.45 3.03 3.03 2.82 2.92 0.79
1.66 3.00 424.66 * 0.012 0.55 0.46 3.10 3.10 2.90 3.00 0.81
1.73 3.09 424.75 * 0.012 0.56 0.47 3.17 3.17 2.98 3.09 0.83
1.73 3.09 424.75 * 0.012 0.56 0.47 3.17 3.17 2.98 3.09 0.83
BACKWATER COMPUTER PROGRAM FOR PIPES
Pipe data from file:CB-8 TO INLET 2.bwp
Surcharge condition at intermediate junctions
Tailwater Elevation:423.61 feet
Discharge Range:0.11 to 0.61 Step of 0.1 [cfs]
Overflow Elevation:428.4 feet
Weir:NONE
Upstream Velocity:0. feet/sec
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PIPE NO. 1: 24 LF - 12"CP @ 12.08% OUTLET: 416.50 INLET: 419.40 INTYP: 5
JUNC NO. 1: OVERFLOW-EL: 426.65 BEND: 0 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.30
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
*******************************************************************************
0.11 4.22 423.62 * 0.012 0.14 0.07 7.11 7.11 4.22 4.22 0.12
0.21 4.21 423.61 * 0.012 0.19 0.09 7.11 7.11 4.21 4.21 0.19
0.31 4.21 423.61 * 0.012 0.23 0.11 7.11 7.11 4.21 4.21 0.25
0.41 4.22 423.62 * 0.012 0.27 0.12 7.11 7.11 4.21 4.22 0.30
0.51 4.22 423.62 * 0.012 0.30 0.14 7.11 7.11 4.21 4.22 0.34
0.61 4.23 423.63 * 0.012 0.33 0.15 7.11 7.11 4.22 4.23 0.38
PIPE NO. 2: 82 LF - 12"CP @ 7.01% OUTLET: 419.40 INLET: 425.15 INTYP: 5
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
*******************************************************************************
0.08 0.12 425.27 * 0.012 0.12 0.07 4.22 4.22 0.12 ***** 0.12
0.16 0.19 425.34 * 0.012 0.17 0.09 4.21 4.21 0.17 ***** 0.19
0.24 0.24 425.39 * 0.012 0.21 0.11 4.21 4.21 0.21 ***** 0.24
0.32 0.28 425.43 * 0.012 0.24 0.13 4.22 4.22 0.24 ***** 0.28
0.39 0.32 425.47 * 0.012 0.26 0.14 4.22 4.22 0.26 ***** 0.32
0.47 0.35 425.50 * 0.012 0.29 0.15 4.23 4.23 0.29 ***** 0.35
BACKWATER COMPUTER PROGRAM FOR PIPES
Pipe data from file:CB-9 TO CB-7.bwp
Surcharge condition at intermediate junctions
Tailwater Elevation:423.63 feet
Discharge Range:0.02 to 0.13 Step of 0.02 [cfs]
Overflow Elevation:424.9 feet
Weir:NONE
Upstream Velocity:0. feet/sec
PIPE NO. 1: 73 LF - 12"CP @ 3.42% OUTLET: 419.40 INLET: 421.90 INTYP: 5
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
*******************************************************************************
0.02 1.74 423.64 * 0.012 0.06 0.04 4.23 4.23 1.74 1.74 0.06
0.04 1.73 423.63 * 0.012 0.09 0.06 4.23 4.23 1.73 1.73 0.09
0.06 1.73 423.63 * 0.012 0.10 0.07 4.23 4.23 1.73 1.73 0.12
0.08 1.73 423.63 * 0.012 0.12 0.08 4.23 4.23 1.73 1.73 0.14
0.10 1.73 423.63 * 0.012 0.13 0.09 4.23 4.23 1.73 1.73 0.16
0.12 1.73 423.63 * 0.012 0.15 0.10 4.23 4.23 1.73 1.73 0.17
0.14 1.73 423.63 * 0.012 0.16 0.10 4.23 4.23 1.73 1.73 0.19
BACKWATER COMPUTER PROGRAM FOR PIPES
Pipe data from file:CB-11 TO CB-1.bwp
Surcharge condition at intermediate junctions
Tailwater Elevation:418.18 feet
Discharge Range:0.11 to 0.91 Step of 0.1 [cfs]
Overflow Elevation:433.42 feet
Weir:NONE
Upstream Velocity:0. feet/sec
PIPE NO. 1: 8 LF - 12"CP @ 1.00% OUTLET: 417.18 INLET: 417.26 INTYP: 5
JUNC NO. 1: OVERFLOW-EL: 419.88 BEND: 68 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.00
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Technical Information Report Renton, Washington
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
*******************************************************************************
0.11 0.93 418.19 * 0.012 0.14 0.12 1.00 1.00 0.93 0.93 0.18
0.21 0.93 418.19 * 0.012 0.19 0.16 1.00 1.00 0.93 0.93 0.25
0.31 0.93 418.19 * 0.012 0.23 0.20 1.00 1.00 0.93 0.93 0.31
0.41 0.94 418.20 * 0.012 0.27 0.23 1.00 1.00 0.93 0.94 0.36
0.51 0.94 418.20 * 0.012 0.30 0.25 1.00 1.00 0.93 0.94 0.40
0.61 0.94 418.20 * 0.012 0.33 0.27 1.00 1.00 0.93 0.94 0.44
0.71 0.95 418.21 * 0.012 0.36 0.30 1.00 1.00 0.93 0.95 0.48
0.81 0.95 418.21 * 0.012 0.38 0.32 1.00 1.00 0.93 0.95 0.52
0.91 0.96 418.22 * 0.012 0.40 0.34 1.00 1.00 0.93 0.96 0.55
PIPE NO. 2: 134 LF - 12"CP @ 0.80% OUTLET: 417.26 INLET: 418.33 INTYP: 5
JUNC NO. 2: OVERFLOW-EL: 424.41 BEND: 64 DEG DIA/WIDTH: 4.0 Q-RATIO: 1.10
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
*******************************************************************************
0.11 0.18 418.51 * 0.012 0.14 0.13 0.93 0.93 0.14 ***** 0.18
0.21 0.25 418.58 * 0.012 0.19 0.17 0.93 0.93 0.19 ***** 0.25
0.31 0.31 418.64 * 0.012 0.23 0.21 0.93 0.93 0.23 ***** 0.31
0.41 0.36 418.69 * 0.012 0.27 0.24 0.94 0.94 0.27 ***** 0.36
0.51 0.40 418.73 * 0.012 0.30 0.26 0.94 0.94 0.30 ***** 0.40
0.61 0.45 418.78 * 0.012 0.33 0.29 0.94 0.94 0.33 ***** 0.45
0.71 0.49 418.82 * 0.012 0.36 0.31 0.95 0.95 0.36 ***** 0.49
0.81 0.52 418.85 * 0.012 0.38 0.33 0.95 0.95 0.38 ***** 0.52
0.91 0.56 418.89 * 0.012 0.40 0.36 0.96 0.96 0.40 ***** 0.56
PIPE NO. 3: 11 LF - 12"CP @ 17.73% OUTLET: 418.33 INLET: 420.28 INTYP: 5
JUNC NO. 3: OVERFLOW-EL: 425.28 BEND: 49 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.00
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
*******************************************************************************
0.05 0.10 420.38 * 0.012 0.10 0.05 0.18 0.18 0.10 ***** 0.05
0.10 0.13 420.41 * 0.012 0.13 0.06 0.25 0.25 0.13 ***** 0.08
0.15 0.16 420.44 * 0.012 0.16 0.07 0.31 0.31 0.16 ***** 0.12
0.20 0.19 420.47 * 0.012 0.19 0.08 0.36 0.36 0.19 ***** 0.16
0.24 0.21 420.49 * 0.012 0.21 0.09 0.40 0.40 0.21 ***** 0.19
0.29 0.23 420.51 * 0.012 0.23 0.10 0.45 0.45 0.23 ***** 0.21
0.34 0.25 420.53 * 0.012 0.25 0.10 0.49 0.49 0.25 ***** 0.24
0.39 0.26 420.54 * 0.012 0.26 0.11 0.52 0.52 0.26 ***** 0.26
0.43 0.28 420.56 * 0.012 0.28 0.12 0.56 0.56 0.28 ***** 0.28
PIPE NO. 4: 151 LF - 12"CP @ 2.93% OUTLET: 420.28 INLET: 424.70 INTYP: 5
JUNC NO. 4: OVERFLOW-EL: 428.40 BEND: 49 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.00
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
*******************************************************************************
0.05 0.11 424.81 * 0.012 0.10 0.07 0.10 0.10 0.10 ***** 0.11
0.10 0.16 424.86 * 0.012 0.13 0.09 0.13 0.13 0.13 ***** 0.16
0.15 0.20 424.90 * 0.012 0.16 0.11 0.16 0.16 0.16 ***** 0.20
0.20 0.23 424.93 * 0.012 0.19 0.12 0.19 0.19 0.19 ***** 0.23
0.24 0.26 424.96 * 0.012 0.21 0.14 0.21 0.21 0.21 ***** 0.26
0.29 0.29 424.99 * 0.012 0.23 0.15 0.23 0.23 0.23 ***** 0.29
0.34 0.31 425.01 * 0.012 0.25 0.16 0.25 0.25 0.25 ***** 0.31
0.39 0.33 425.03 * 0.012 0.26 0.17 0.26 0.26 0.26 ***** 0.33
0.43 0.36 425.06 * 0.012 0.28 0.18 0.28 0.28 0.28 ***** 0.36
PIPE NO. 5: 132 LF - 12"CP @ 4.46% OUTLET: 424.70 INLET: 430.59 INTYP: 5
2016 D. R. STRONG Consulting Engineers Inc. Page 60 Bethany Corner
Technical Information Report Renton, Washington
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
*******************************************************************************
0.05 0.10 430.69 * 0.012 0.10 0.06 0.11 0.11 0.10 ***** 0.10
0.10 0.15 430.74 * 0.012 0.13 0.08 0.16 0.16 0.13 ***** 0.15
0.15 0.19 430.78 * 0.012 0.16 0.10 0.20 0.20 0.16 ***** 0.19
0.20 0.22 430.81 * 0.012 0.19 0.11 0.23 0.23 0.19 ***** 0.22
0.24 0.25 430.84 * 0.012 0.21 0.12 0.26 0.26 0.21 ***** 0.25
0.29 0.28 430.87 * 0.012 0.23 0.13 0.29 0.29 0.23 ***** 0.28
0.34 0.31 430.90 * 0.012 0.25 0.14 0.31 0.31 0.25 ***** 0.31
0.39 0.33 430.92 * 0.012 0.26 0.15 0.33 0.33 0.26 ***** 0.33
0.43 0.35 430.94 * 0.012 0.28 0.16 0.36 0.36 0.28 ***** 0.35
2016 D. R. STRONG Consulting Engineers Inc. Page 61 Bethany Corner
Technical Information Report Renton, Washington
SECTION VI
SPECIAL REPORTS AND STUDIES
The following report and studies have been provided with this submittal.
Critical Areas Study: Mark Rigos, P.E. – December 10st, 2016
Subsurface Exploration and Geotechnical Engineering Report: Associated Earth
Sciences Incorporated – December 16, 2016
Arborist Report: Tree Harmony Arborists, LLC – December 12, 2016
2016 D. R. STRONG Consulting Engineers Inc. Page 62 Bethany Corner
Technical Information Report Renton, Washington
SECTION VII
OTHER PERMITS, VARIANCES AND ADJUSTMENTS
None at this time.
2016 D. R. STRONG Consulting Engineers Inc. Page 63 Bethany Corner
Technical Information Report Renton, Washington
SECTION VIII
CSWPPP ANALYSIS AND DESIGN (PART A)
The Erosion and Sedimentation Control Design will meet the seven minimum King
County requirements:
1. Areas to remain undisturbed shall be delineated with a high visibility plastic fence
prior to any site clearing or grading.
2. Site disturbed areas shall be covered with mulch and seeded, as appropriate, for
temporary or permanent measures.
3. Perimeter protection shall consist of a silt fence down slope of any disturbed areas
or stockpiles.
4. A stabilized construction entrance will be located at the point of ingress/egress (i.e.
onsite access road).
5. The detention pond will act as a sediment pond for sediment retention. Perimeter
silt fences will provide sediment retention within the bypass areas.
6. Surface water from disturbed areas will sheet flow to the sediment pond for
treatment.
7. Dust control shall be provided by spraying exposed soils with water until wet. This is
required when exposed soils are dry to the point that wind transport is possible
which would impact roadways, drainage ways, surface waters, or neighboring
residences.
SWPPP PLAN DESIGN (PART B)
Construction activities that could contribute pollutants to surface and storm water
include the following, with applicable BMP’s listed for each item:
1. Storage and use of chemicals: Utilize source control, and soil erosion and
sedimentation control practices, such as using only recommended amounts of
chemical materials applied in the proper manner; neutralizing concrete wash
water, and disposing of excess concrete material only in areas prepared for
concrete placement, or return to batch plant; disposing of wash-up waters from
water-based paints in sanitary sewer; disposing of wastes from oil-based paints,
solvents, thinners, and mineral spirits only through a licensed waste
management firm, or treatment, storage, and disposal (TSD) facility.
2. Material delivery and storage: Locate temporary storage areas away from
vehicular traffic, near the construction entrance, and away from storm drains.
Material Safety Data Sheets (MSDS) should be supplied for all materials stored,
and chemicals kept in their original labeled containers. Maintenance, fueling,
and repair of heavy equipment and vehicles shall be conducted using spill
prevention and control measures. Contaminated surfaces shall be cleaned
immediately following any spill incident. Provide cover, containment, and
protection from vandalism for all chemicals, liquid products, petroleum products,
and other potentially hazardous materials.
2016 D. R. STRONG Consulting Engineers Inc. Page 64 Bethany Corner
Technical Information Report Renton, Washington
3. Building demolition: Protect stormwater drainage system from sediment-laden
runoff and loose particles. To the extent possible, use dikes, berms, or other
methods to protect overland discharge paths from runoff. Street gutter,
sidewalks, driveways, and other paved surfaces in the immediate area of
demolition must be swept daily to collect and properly dispose of loose debris
and garbage. Spray the minimum amount of water to help control windblown fine
particles such as concrete, dust, and paint chips. Avoid excessive spraying so
that runoff from the site does not occur, yet dust control is achieved. Oils must
never be used for dust control.
4. Sawcutting: Slurry and cuttings shall be vacuumed during the activity to prevent
migration offsite and must not remain on permanent concrete or asphalt paving
overnight. Collected slurry and cuttings shall be disposed of in a manner that
does not violate ground water or surface water quality standards.
The complete CSWPPP can be found in Appendix B.
2016 D. R. STRONG Consulting Engineers Inc. Page 65 Bethany Corner
Technical Information Report Renton, Washington
SECTION IX
BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT
1. Bond Quantity Worksheet – is located in Appendix C
2. The Stormwater Facility Summary Sheet is included in this section
2016 D. R. STRONG Consulting Engineers Inc. Page 66 Bethany Corner
Technical Information Report Renton, Washington
STORMWATER FACILITY SUMMARY SHEET
Development Bethany Corner Date December 15, 2016
Location: 16433 & 16451 111th Avenue SE, Renton, Washington
ENGINEER DEVELOPER
Name Jonathan S. Murray, P.E. Name Mark Seek
Firm D. R. STRONG Consulting
Engineers, Inc.
Firm
Address 620 7th Avenue Address… 15233 Manion Way NE
Kirkland, WA 98033 Duvall, WA 98019
Phone (425) 827-3063 Phone (425) 919-4062
Developed Site: 1.942 acres
Number of lots: 9
Number of detention facilities on site: Number of infiltration facilities on site:
___1__ vaults ______ vaults
______ pond ______ ponds
______ tanks ______ tanks
Flow control provided in regional facility (give location)___________________________
No flow control required_____ Exemption number ______________________________
Downstream Drainage Basins
Immediate Major Basin
Basin Benson Green/Duwamish River
Watershed
Number & type of water quality facilities on site:
biofiltration swale (regular/wet/ or continuous inflow?)
______ sand filter (basic or large?) ______ sand filter, linear (basic or
large?) ______ CONTECH Stormfilter
__1___ combined detention/WQ vault ______ sand filter vault (basic or large?)
______ combined detention/wetpond ______ stormwater wetland
______ compost filter ______ wetvault (basic or large?)
______ filter strip ______ Wetvault
______ flow dispersion ______ pre-settling pond
______ farm management plan ______ flow-splitter catchbasin
______ landscape management plan
______ oil/water separator (baffle or coalescing plate?)
______ catch basin inserts:
Manufacturer____________________________________________
2016 D. R. STRONG Consulting Engineers Inc. Page 67 Bethany Corner
Technical Information Report Renton, Washington
______ pre-settling structure:
Manufacturer__________________________________________
DESIGN INFORMATION INDIVIDUAL BASIN
Water Quality design flow
Water Quality treated volume
Drainage basin(s) 1
Onsite area (includes frontage) 1.942
Offsite area 0.0
Type of Storage Facility Detention
Vault
Live Storage Volume (required) 22,080
Predev Runoff Rate 2-year 0.061
10-year 0.103
100-year 0.176
Developed Runoff Rate 2-year 0.032
(includes bypass) 10-year 0.095
100-year 0.456
Type of Restrictor
Size of orifice/restriction No. 1 0.75” Ø 0.00’
No. 2 1.375” Ø 3.23’
No. 3
2016 D. R. STRONG Consulting Engineers Inc. Page 68 Bethany Corner
Technical Information Report Renton, Washington
SECTION X
OPERATIONS AND MAINTENANCE MANUAL
The Home Owners Association will be responsible for maintenance of several private
catch basins on various lots as depicted on the plans. Maintenance guidelines set forth
in the 2009 KCSWDM are included in this section. All other drainage elements are to be
publicly maintained.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009 A-5
NO. 3 – DETENTION TANKS AND VAULTS
Maintenance
Component
Defect or Problem Conditions When Maintenance is Needed Results Expected When
Maintenance is Performed
Trash and debris Any trash and debris which exceed 1 cubic foot
per 1,000 square feet (this is about equal to the
amount of trash it would take to fill up one
standard size office garbage can). In general,
there should be no visual evidence of dumping.
Trash and debris cleared from site.
Noxious weeds Any noxious or nuisance vegetation which may
constitute a hazard to County personnel or the
public.
Noxious and nuisance vegetation
removed according to applicable
regulations. No danger of noxious
vegetation where County personnel or the public might normally be.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Site
Grass/groundcover Grass or groundcover exceeds 18 inches in
height.
Grass or groundcover mowed to a
height no greater than 6 inches.
Trash and debris Any trash and debris accumulated in vault or tank (includes floatables and non-floatables). No trash or debris in vault. Tank or Vault Storage Area
Sediment
accumulation
Accumulated sediment depth exceeds 10% of the
diameter of the storage area for ½ length of
storage vault or any point depth exceeds 15% of
diameter. Example: 72-inch storage tank would
require cleaning when sediment reaches depth of
7 inches for more than ½ length of tank.
All sediment removed from storage
area.
Plugged air vent Any blockage of the vent. Tank or vault freely vents.
Tank bent out of
shape
Any part of tank/pipe is bent out of shape more
than 10% of its design shape.
Tank repaired or replaced to design.
Tank Structure
Gaps between
sections, damaged
joints or cracks or
tears in wall
A gap wider than ½-inch at the joint of any tank
sections or any evidence of soil particles entering
the tank at a joint or through a wall.
No water or soil entering tank
through joints or walls.
Vault Structure Damage to wall,
frame, bottom, and/or
top slab
Cracks wider than ½-inch, any evidence of soil
entering the structure through cracks or qualified
inspection personnel determines that the vault is
not structurally sound.
Vault is sealed and structurally
sound.
Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Inlet/Outlet Pipes
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
1/9/2009 2009 Surface Water Design Manual – Appendix A A-6
NO. 3 – DETENTION TANKS AND VAULTS
Maintenance
Component
Defect or Problem Conditions When Maintenance is Needed Results Expected When
Maintenance is Performed
Cover/lid not in place Cover/lid is missing or only partially in place.
Any open manhole requires immediate
maintenance.
Manhole access covered.
Locking mechanism
not working
Mechanism cannot be opened by one
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Mechanism opens with proper tools.
Cover/lid difficult to
remove
One maintenance person cannot remove
cover/lid after applying 80 lbs of lift.
Cover/lid can be removed and
reinstalled by one maintenance
person.
Access Manhole
Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards.
Allows maintenance person safe
access.
Damaged or difficult
to open
Large access doors or plates cannot be
opened/removed using normal equipment.
Replace or repair access door so it
can opened as designed.
Gaps, doesn't cover
completely
Large access doors not flat and/or access
opening not completely covered.
Doors close flat and covers access
opening completely.
Large access
doors/plate
Lifting Rings missing,
rusted
Lifting rings not capable of lifting weight of door
or plate.
Lifting rings sufficient to lift or
remove door or plate.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009 A-7
NO. 4 – CONTROL STRUCTURE/FLOW RESTRICTOR
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Trash or debris of more than ½ cubic foot which
is located immediately in front of the structure
opening or is blocking capacity of the structure by
more than 10%.
No Trash or debris blocking or
potentially blocking entrance to
structure.
Trash or debris in the structure that exceeds 1/3the depth from the bottom of basin to invert the
lowest pipe into or out of the basin.
No trash or debris in the structure.
Trash and debris
Deposits of garbage exceeding 1 cubic foot in
volume.
No condition present which would
attract or support the breeding of
insects or rodents.
Sediment Sediment exceeds 60% of the depth from the
bottom of the structure to the invert of the lowest
pipe into or out of the structure or the bottom of
the FROP-T section or is within 6 inches of the
invert of the lowest pipe into or out of the
structure or the bottom of the FROP-T section.
Sump of structure contains no
sediment.
Corner of frame extends more than ¾ inch past
curb face into the street (If applicable).
Frame is even with curb.
Top slab has holes larger than 2 square inches or
cracks wider than ¼ inch.
Top slab is free of holes and cracks.
Damage to frame
and/or top slab
Frame not sitting flush on top slab, i.e.,
separation of more than ¾ inch of the frame from
the top slab.
Frame is sitting flush on top slab.
Cracks wider than ½ inch and longer than 3 feet,
any evidence of soil particles entering structure
through cracks, or maintenance person judges
that structure is unsound.
Structure is sealed and structurally
sound.
Cracks in walls or
bottom
Cracks wider than ½ inch and longer than 1 foot
at the joint of any inlet/outlet pipe or any evidence
of soil particles entering structure through cracks.
No cracks more than 1/4 inch wide at
the joint of inlet/outlet pipe.
Settlement/
misalignment
Structure has settled more than 1 inch or has
rotated more than 2 inches out of alignment.
Basin replaced or repaired to design
standards.
Damaged pipe joints Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
the structure at the joint of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of inlet/outlet pipes.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Structure
Ladder rungs missing
or unsafe
Ladder is unsafe due to missing rungs,
misalignment, rust, cracks, or sharp edges.
Ladder meets design standards and
allows maintenance person safe
access.
T section is not securely attached to structure
wall and outlet pipe structure should support at
least 1,000 lbs of up or down pressure.
T section securely attached to wall
and outlet pipe.
Structure is not in upright position (allow up to
10% from plumb).
Structure in correct position.
Connections to outlet pipe are not watertight or
show signs of deteriorated grout.
Connections to outlet pipe are water
tight; structure repaired or replaced
and works as designed.
FROP-T Section Damage
Any holes—other than designed holes—in the
structure.
Structure has no holes other than
designed holes.
Cleanout Gate Damaged or missing Cleanout gate is missing. Replace cleanout gate.
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
1/9/2009 2009 Surface Water Design Manual – Appendix A A-8
NO. 4 – CONTROL STRUCTURE/FLOW RESTRICTOR
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Cleanout gate is not watertight. Gate is watertight and works as
designed.
Gate cannot be moved up and down by one
maintenance person.
Gate moves up and down easily and
is watertight.
Chain/rod leading to gate is missing or damaged. Chain is in place and works as
designed.
Damaged or missing Control device is not working properly due to
missing, out of place, or bent orifice plate.
Plate is in place and works as
designed.
Orifice Plate
Obstructions Any trash, debris, sediment, or vegetation
blocking the plate.
Plate is free of all obstructions and
works as designed.
Obstructions Any trash or debris blocking (or having the
potential of blocking) the overflow pipe.
Pipe is free of all obstructions and
works as designed.
Overflow Pipe
Deformed or damaged
lip
Lip of overflow pipe is bent or deformed. Overflow pipe does not allow
overflow at an elevation lower than
design
Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Inlet/Outlet Pipe
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design
standards.
Trash and debris Trash and debris that is blocking more than 20%
of grate surface.
Grate free of trash and debris.
footnote to guidelines for disposal
Metal Grates
(If Applicable)
Damaged or missing Grate missing or broken member(s) of the grate. Grate is in place and meets design
standards.
Cover/lid not in place Cover/lid is missing or only partially in place.
Any open structure requires urgent
maintenance.
Cover/lid protects opening to
structure.
Locking mechanism
Not Working
Mechanism cannot be opened by one
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Mechanism opens with proper tools.
Manhole Cover/Lid
Cover/lid difficult to
Remove
One maintenance person cannot remove
cover/lid after applying 80 lbs. of lift.
Cover/lid can be removed and
reinstalled by one maintenance
person.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009 A-9
NO. 5 – CATCH BASINS AND MANHOLES
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Sediment Sediment exceeds 60% of the depth from the
bottom of the catch basin to the invert of the
lowest pipe into or out of the catch basin or is
within 6 inches of the invert of the lowest pipe
into or out of the catch basin.
Sump of catch basin contains no
sediment.
Trash or debris of more than ½ cubic foot which
is located immediately in front of the catch basin
opening or is blocking capacity of the catch basin
by more than 10%.
No Trash or debris blocking or
potentially blocking entrance to
catch basin.
Trash or debris in the catch basin that exceeds 1/3 the depth from the bottom of basin to invert the
lowest pipe into or out of the basin.
No trash or debris in the catch basin.
Dead animals or vegetation that could generate
odors that could cause complaints or dangerous
gases (e.g., methane).
No dead animals or vegetation
present within catch basin.
Trash and debris
Deposits of garbage exceeding 1 cubic foot in
volume.
No condition present which would
attract or support the breeding of
insects or rodents.
Corner of frame extends more than ¾ inch past
curb face into the street (If applicable).
Frame is even with curb.
Top slab has holes larger than 2 square inches or
cracks wider than ¼ inch.
Top slab is free of holes and cracks.
Damage to frame
and/or top slab
Frame not sitting flush on top slab, i.e.,
separation of more than ¾ inch of the frame from
the top slab.
Frame is sitting flush on top slab.
Cracks wider than ½ inch and longer than 3 feet,
any evidence of soil particles entering catch
basin through cracks, or maintenance person
judges that catch basin is unsound.
Catch basin is sealed and
structurally sound.
Cracks in walls or
bottom
Cracks wider than ½ inch and longer than 1 foot
at the joint of any inlet/outlet pipe or any evidence
of soil particles entering catch basin through
cracks.
No cracks more than 1/4 inch wide at
the joint of inlet/outlet pipe.
Settlement/
misalignment
Catch basin has settled more than 1 inch or has
rotated more than 2 inches out of alignment.
Basin replaced or repaired to design
standards.
Damaged pipe joints Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
the catch basin at the joint of the inlet/outlet
pipes.
No cracks more than ¼-inch wide at
the joint of inlet/outlet pipes.
Structure
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Inlet/Outlet Pipe
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
1/9/2009 2009 Surface Water Design Manual – Appendix A A-10
NO. 5 – CATCH BASINS AND MANHOLES
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design
standards.
Trash and debris Trash and debris that is blocking more than 20%
of grate surface.
Grate free of trash and debris.
footnote to guidelines for disposal
Metal Grates
(Catch Basins)
Damaged or missing Grate missing or broken member(s) of the grate.
Any open structure requires urgent
maintenance.
Grate is in place and meets design
standards.
Cover/lid not in place Cover/lid is missing or only partially in place.
Any open structure requires urgent
maintenance.
Cover/lid protects opening to
structure.
Locking mechanism
Not Working
Mechanism cannot be opened by one
maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not
work.
Mechanism opens with proper tools.
Manhole Cover/Lid
Cover/lid difficult to
Remove
One maintenance person cannot remove
cover/lid after applying 80 lbs. of lift.
Cover/lid can be removed and
reinstalled by one maintenance
person.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009 A-11
NO. 6 – CONVEYANCE PIPES AND DITCHES
Maintenance
Component
Defect or Problem Conditions When Maintenance is Needed Results Expected When
Maintenance is Performed
Sediment & debris
accumulation
Accumulated sediment or debris that exceeds
20% of the diameter of the pipe.
Water flows freely through pipes.
Vegetation/roots Vegetation/roots that reduce free movement of
water through pipes.
Water flows freely through pipes.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Damage to protective
coating or corrosion
Protective coating is damaged; rust or corrosion
is weakening the structural integrity of any part of
pipe.
Pipe repaired or replaced.
Pipes
Damaged Any dent that decreases the cross section area of
pipe by more than 20% or is determined to have
weakened structural integrity of the pipe.
Pipe repaired or replaced.
Trash and debris Trash and debris exceeds 1 cubic foot per 1,000
square feet of ditch and slopes.
Trash and debris cleared from
ditches.
Sediment
accumulation
Accumulated sediment that exceeds 20% of the
design depth.
Ditch cleaned/flushed of all sediment
and debris so that it matches design.
Noxious weeds Any noxious or nuisance vegetation which may
constitute a hazard to County personnel or the
public.
Noxious and nuisance vegetation
removed according to applicable
regulations. No danger of noxious
vegetation where County personnel
or the public might normally be.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Vegetation Vegetation that reduces free movement of water
through ditches.
Water flows freely through ditches.
Erosion damage to
slopes
Any erosion observed on a ditch slope. Slopes are not eroding.
Ditches
Rock lining out of
place or missing (If
Applicable)
One layer or less of rock exists above native soil
area 5 square feet or more, any exposed native
soil.
Replace rocks to design standards.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009 A-15
NO. 10 – GATES/BOLLARDS/ACCESS BARRIERS
Maintenance
Component
Defect or Problem Conditions When Maintenance is Needed Results Expected When
Maintenance is Performed
Missing gate. Gates in place.
Broken or missing hinges such that gate cannot
be easily opened and closed by a maintenance
person.
Hinges intact and lubed. Gate is
working freely.
Gate is out of plumb more than 6 inches and
more than 1 foot out of design alignment.
Gate is aligned and vertical.
Damaged or missing
members
Missing stretcher bar, stretcher bands, and ties. Stretcher bar, bands, and ties in
place.
Locking mechanism
does not lock gate
Locking device missing, no-functioning or does
not link to all parts.
Locking mechanism prevents
opening of gate.
Chain Link Fencing
Gate
Openings in fabric Openings in fabric are such that an 8-inch
diameter ball could fit through.
Fabric mesh openings within 50% of
grid size.
Damaged or missing
cross bar
Cross bar does not swing open or closed, is
missing or is bent to where it does not prevent
vehicle access.
Cross bar swings fully open and
closed and prevents vehicle access.
Locking mechanism
does not lock gate
Locking device missing, no-functioning or does
not link to all parts.
Locking mechanism prevents
opening of gate.
Bar Gate
Support post
damaged
Support post does not hold cross bar up. Cross bar held up preventing vehicle
access into facility.
Damaged or missing Bollard broken, missing, does not fit into support
hole or hinge broken or missing.
No access for motorized vehicles to
get into facility.
Bollards
Does not lock Locking assembly or lock missing or cannot be
attached to lock bollard in place.
No access for motorized vehicles to
get into facility.
Dislodged Boulders not located to prevent motorized vehicle
access.
No access for motorized vehicles to
get into facility.
Boulders
Circumvented Motorized vehicles going around or between
boulders.
No access for motorized vehicles to
get into facility.
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
1/9/2009 2009 Surface Water Design Manual – Appendix A A-16
NO. 11 – GROUNDS (LANDSCAPING)
Maintenance
Component
Defect or Problem Conditions When Maintenance is Needed Results Expected When
Maintenance is Performed
Trash or litter Any trash and debris which exceed 1 cubic foot
per 1,000 square feet (this is about equal to the
amount of trash it would take to fill up one
standard size office garbage can). In general,
there should be no visual evidence of dumping.
Trash and debris cleared from site.
Noxious weeds Any noxious or nuisance vegetation which may
constitute a hazard to County personnel or the
public.
Noxious and nuisance vegetation
removed according to applicable
regulations. No danger of noxious
vegetation where County personnel or the public might normally be.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Site
Grass/groundcover Grass or groundcover exceeds 18 inches in
height.
Grass or groundcover mowed to a
height no greater than 6 inches.
Hazard Any tree or limb of a tree identified as having a potential to fall and cause property damage or
threaten human life.A hazard tree identified by
a qualified arborist must be removed as soon
as possible.
No hazard trees in facility.
Limbs or parts of trees or shrubs that are split or
broken which affect more than 25% of the total
foliage of the tree or shrub.
Trees and shrubs with less than 5%
of total foliage with split or broken
limbs.
Trees or shrubs that have been blown down or
knocked over.
No blown down vegetation or
knocked over vegetation. Trees or
shrubs free of injury.
Trees and Shrubs
Damaged
Trees or shrubs which are not adequately
supported or are leaning over, causing exposure
of the roots.
Tree or shrub in place and
adequately supported; dead or
diseased trees removed.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009 A-17
NO. 12 – ACCESS ROADS
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Trash and debris exceeds 1 cubic foot per 1,000
square feet (i.e., trash and debris would fill up
one standards size garbage can).
Roadway drivable by maintenance
vehicles.
Trash and debris
Debris which could damage vehicle tires or
prohibit use of road.
Roadway drivable by maintenance
vehicles.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Any obstruction which reduces clearance above
road surface to less than 14 feet.
Roadway overhead clear to 14 feet
high.
Site
Blocked roadway
Any obstruction restricting the access to a 10- to
12 foot width for a distance of more than 12 feet
or any point restricting access to less than a 10
foot width.
At least 12-foot of width on access
road.
Erosion, settlement,
potholes, soft spots,
ruts
Any surface defect which hinders or prevents
maintenance access.
Road drivable by maintenance
vehicles.
Road Surface
Vegetation on road
surface
Trees or other vegetation prevent access to
facility by maintenance vehicles.
Maintenance vehicles can access
facility.
Erosion Erosion within 1 foot of the roadway more than 8
inches wide and 6 inches deep.
Shoulder free of erosion and
matching the surrounding road.
Shoulders and
Ditches
Weeds and brush Weeds and brush exceed 18 inches in height or
hinder maintenance access.
Weeds and brush cut to 2 inches in
height or cleared in such a way as to
allow maintenance access.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Modular Grid
Pavement
Damaged or missing Access surface compacted because of broken on
missing modular block.
Access road surface restored so
road infiltrates.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009 A-23
NO. 17 – WETVAULT
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Site Trash and debris Trash and debris accumulated on facility site. Trash and debris removed from
facility site.
Trash and debris Any trash and debris accumulated in vault
(includes floatables and non-floatables).
No trash or debris in vault.
Sediment
accumulation
Sediment accumulation in vault bottom exceeds
the depth of the sediment zone plus 6 inches.
No sediment in vault.
Treatment Area
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Damage to wall,
frame, bottom, and/or
top slab
Cracks wider than ½-inch, any evidence of soil
entering the structure through cracks, vault does
not retain water or qualified inspection personnel
determines that the vault is not structurally
sound.
Vault is sealed and structurally
sound.
Baffles damaged Baffles corroding, cracking, warping and/or
showing signs of failure or baffle cannot be
removed.
Repair or replace baffles or walls to
specifications.
Vault Structure
Ventilation Ventilation area blocked or plugged. No reduction of ventilation area
exists.
Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Inlet/Outlet Pipe
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
Inoperable valve Valve will not open and close. Valve opens and closes normally. Gravity Drain
Valve won’t seal Valve does not seal completely. Valve completely seals closed.
Access cover/lid
damaged or difficult to
open
Access cover/lid cannot be easily opened by one
person. Corrosion/deformation of cover/lid.
Access cover/lid can be opened by
one person.
Locking mechanism
not working
Mechanism cannot be opened by one
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Mechanism opens with proper tools.
Cover/lid difficult to
remove
One maintenance person cannot remove
cover/lid after applying 80 lbs of lift.
Cover/lid can be removed and
reinstalled by one maintenance
person.
Access doors/plate
has gaps, doesn't
cover completely
Large access doors not flat and/or access
opening not completely covered.
Doors close flat and covers access
opening completely.
Lifting Rings missing,
rusted
Lifting rings not capable of lifting weight of door
or plate.
Lifting rings sufficient to lift or
remove door or plate.
Access Manhole
Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards.
Allows maintenance person safe
access.
2016 D. R. STRONG Consulting Engineers Inc. Page 69 Bethany Corner
Technical Information Report Renton, Washington
APPENDICES
2016 D. R. STRONG Consulting Engineers Inc. Page 70 Bethany Corner
Technical Information Report Renton, Washington
APPENDIX “A” LEGAL DESCRIPTION
LOT 11, BLOCK 7, AKER'S FARMS NO. 6, ACCORDING TO THE PLAT THEREOF
RECORDED IN VOLUME 42 OF PLATS, PAGE 15, RECORDS OF KING COUNTY,
WASHINGTON;
SITUATE IN THE COUNTY OF KING, STATE OF WASHINGTON.
LOT 12, BLOCK 7, AKER'S FARMS NO. 6 ACCORDING TO PLAT RECORDED IN
VOLUME 42 OF PLATS, PAGE 15, RECORDS OF KING COUNTY WASHINGTON.
SITUATE IN THE COUNTY OF KING, STATE OF WASHINGTON.
2016 D. R. STRONG Consulting Engineers Inc. Page 71 Bethany Corner
Technical Information Report Renton, Washington
APPENDIX “B” CSWPPP
D.R. STRONG Consulting Engineers, Inc. Bethany Corner
Stormwater Pollution Prevention Plan
Construction Stormwater General Permit
Stormwater Pollution Prevention Plan
(SWPPP)
for
Bethany Corner
Prepared for:
The Washington State Department of Ecology
Northwest Regional Office
3190 16th Avenue SE
Bellevue, WA 98008-5452
Permittee / Owner Developer Operator / Contractor
Mark Seek
15233 Manion Way NE
Duvall, WA 98019
TBD TBD
16433 & 16451 111th Avenue SE, Renton, Washington
Certified Erosion and Sediment Control Lead (CESCL)
Name Organization Contact Phone Number
TBD Associated Earth Sciences,
Inc
425.827.7701
SWPPP Prepared By
Name Organization Contact Phone Number
Jonathan S. Murray, PE DR Strong Consulting
Engineers, Inc.
(425) 827-3063
SWPPP Preparation Date
December 15, 2016
Project Construction Dates
Activity / Phase Start Date End Date
Site Development 4/2017 10/2018
D.R. STRONG Consulting Engineers, Inc. Bethany Corner
Stormwater Pollution Prevention Plan Page i
Table of Contents
1 Project Information ...............................................................................................................2
1.1 Existing Conditions .......................................................................................................2
1.2 Proposed Construction Activities ...................................................................................2
2 Construction Stormwater Best Management Practices (BMPs) ............................................4
2.1 The 12 Elements ...........................................................................................................4
2.1.1 Element 1: Preserve Vegetation / Mark Clearing Limits .........................................4
2.1.2 Element 2: Establish Construction Access .............................................................5
2.1.3 Element 3: Control Flow Rates...............................................................................6
2.1.4 Element 4: Install Sediment Controls .....................................................................7
2.1.5 Element 5: Stabilize Soils.......................................................................................9
2.1.6 Element 6: Protect Slopes....................................................................................10
2.1.7 Element 7: Protect Drain Inlets.............................................................................11
2.1.8 Element 8: Stabilize Channels and Outlets ..........................................................12
2.1.9 Element 9: Control Pollutants ...............................................................................13
2.1.10 Element 10: Control Dewatering ..........................................................................16
2.1.11 Element 11: Maintain BMPs .................................................................................17
2.1.12 Element 12: Manage the Project ..........................................................................18
3 Pollution Prevention Team .................................................................................................20
4 Monitoring and Sampling Requirements ............................................................................21
4.1 Site Inspection ............................................................................................................21
4.2 Stormwater Quality Sampling ......................................................................................21
4.2.1 Turbidity Sampling ...............................................................................................22
4.2.2 pH Sampling ........................................................................................................23
5 Discharges to 303(d) or Total Maximum Daily Load (TMDL) Waterbodies .........................24
5.1 303(d) Listed Waterbodies ..........................................................................................24
5.2 TMDL Waterbodies .....................................................................................................24
6 Reporting and Record Keeping ..........................................................................................25
6.1 Record Keeping ..........................................................................................................25
6.1.1 Site Log Book ......................................................................................................25
6.1.2 Records Retention ...............................................................................................25
6.1.3 Updating the SWPPP ...........................................................................................25
6.2 Reporting ....................................................................................................................25
6.2.1 Discharge Monitoring Reports ..............................................................................25
6.2.2 Notification of Noncompliance ..............................................................................26
D.R. STRONG Consulting Engineers, Inc. Bethany Corner
Stormwater Pollution Prevention Plan Page ii
List of Tables
Table 1 – Summary of Site Pollutant Constituents .................................................................2
Table 3 – pH-Modifying Sources ............................................................................................15
Table 5 – Management ............................................................................................................18
Table 7 – Team Information ....................................................................................................20
Table 8 – Turbidity Sampling Method ....................................................................................22
Table 9 – pH Sampling Method ..............................................................................................23
List of Appendices
A. Site Map
B. BMP Detail
C. Correspondence
D. Site Inspection Form
E. Construction Stormwater General Permit (CSWGP)
F. Engineering Calculations
D.R. STRONG Consulting Engineers, Inc. Bethany Corner
Stormwater Pollution Prevention Plan Page 1
List of Acronyms and Abbreviations
Acronym / Abbreviation Explanation
303(d) Section of the Clean Water Act pertaining to Impaired Waterbodies
BFO Bellingham Field Office of the Department of Ecology
BMP(s) Best Management Practice(s)
CESCL Certified Erosion and Sediment Control Lead
CO2 Carbon Dioxide
CRO Central Regional Office of the Department of Ecology
CSWGP Construction Stormwater General Permit
CWA Clean Water Act
DMR Discharge Monitoring Report
DO Dissolved Oxygen
Ecology Washington State Department of Ecology
EPA United States Environmental Protection Agency
ERO Eastern Regional Office of the Department of Ecology
ERTS Environmental Report Tracking System
ESC Erosion and Sediment Control
GULD General Use Level Designation
NPDES National Pollutant Discharge Elimination System
NTU Nephelometric Turbidity Units
NWRO Northwest Regional Office of the Department of Ecology
pH Power of Hydrogen
RCW Revised Code of Washington
SPCC Spill Prevention, Control, and Countermeasure
su Standard Units
SWMMEW Stormwater Management Manual for Eastern Washington
SWMMWW Stormwater Management Manual for Western Washington
SWPPP Stormwater Pollution Prevention Plan
TESC Temporary Erosion and Sediment Control
SWRO Southwest Regional Office of the Department of Ecology
TMDL Total Maximum Daily Load
VFO Vancouver Field Office of the Department of Ecology
WAC Washington Administrative Code
WSDOT Washington Department of Transportation
WWHM Western Washington Hydrology Model
D.R. STRONG Consulting Engineers, Inc. Bethany Corner
Stormwater Pollution Prevention Plan Page 2
1 Project Information
Project/Site Name: Bethany Corner
Street/Location: 16433 & 16451 111th Avenue SE
City: Renton State: WA Zip code: 98055
Subdivision: N/A
Receiving waterbody: Green/Duwamish River watershed
1.1 Existing Conditions
Total acreage (including support activities such as off-site equipment staging yards, material
storage areas, borrow areas).
Total acreage: 1.96
Disturbed acreage: 1.96
Existing structures: 0.15
Landscape topography: 1.68 (estimate)
Drainage patterns: 0.00
Existing Vegetation: 0.00 (estimate)
Critical Areas (wetlands, streams, high erosion
risk, steep or difficult to stabilize slopes): 0.01
Stream and adjacent wetland
List of known impairments for 303(d) listed or Total Maximum Daily Load (TMDL) for the
receiving waterbody:
Green River – Dissolved Oxygen, Temperature, Bioassessment, pH
Table 1 includes a list of suspected and/or known contaminants associated with the construction
activity.
Table 1 – Summary of Site Pollutant Constituents
Constituent
(Pollutant) Location Depth Concentration
No known contaminants exist on the Site
1.2 Proposed Construction Activities
The applicant is seeking approval to subdivide 1.83 acres into nine single–family residential lots
(Project), with lot sizes ranging from approximately 5,948 s.f. to 7,118 s.f. All existing
improvements located on the Site will be demolished or removed during plat construction.
The proposed impervious surface includes an internal plat road, Road A, which will have a
proposed 53-foot right of way and will be improved with 26 feet of pavement ,vertical curbs, 8’
planter strip and 5’ sidewalks. Frontage improvements will be made to 111th AVE SE, including
catch basins, vertical gutter, and 5 foot sidewalk. Lot improvements will include single family
residential houses and associated driveways. The total proposed impervious area for the Site is
50,896 s.f.
D.R. STRONG Consulting Engineers, Inc. Bethany Corner
Stormwater Pollution Prevention Plan Page 3
Construction work will be completed under the Site Development permit. Activities will include
installation of sewer, water and dry utilities; installation of storm sewer; construction of
stormwater detention vault; road and sidewalks; and landscaping.
Runoff will be collected and conveyed to the proposed detention vault. Appendix A shows the
Site Plan with T.E.S.C. measures.
Final stabilization of the disturbed land will include:
• Asphalt roadway
• Concrete sidewalks
• Formal landscape planting
Contaminated Site Information: No known contamination exists on Site.
Proposed activities regarding contaminated soils or groundwater (example: on-site treatment
system, authorized sanitary sewer discharge):
Not applicable as no known contamination.
D.R. STRONG Consulting Engineers, Inc. Bethany Corner
Stormwater Pollution Prevention Plan Page 4
2 Construction Stormwater Best Management Practices (BMPs)
The SWPPP is a living document reflecting current conditions and changes throughout the life
of the project. These changes may be informal (i.e., hand-written notes and deletions). Update
the SWPPP when the CESCL has noted a deficiency in BMPs or deviation from original design.
2.1 The 12 Elements
2.1.1 Element 1: Preserve Vegetation / Mark Clearing Limits
To protect adjacent properties and reduce the area of soil exposed to construction, the limits of
construction will be clearly marked before land-disturbing activities begin. Trees that are to be
preserved, as well as all sensitive areas and their buffers, shall be clearly delineated, both in the
field and on the plans.
In general, natural vegetation and native topsoil shall be retained in an undisturbed state to the
maximum extent possible. The BMPs relevant to marking the clearing limits that will be applied
for this project include:
The plastic or metal fence will be placed around the perimeter of the developable area of the
Site. BMP will be implemented at the start of construction.
Alternate BMPs for marking clearing limits are included in Appendix B as a quick reference tool
for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or
inappropriate during construction to satisfy the requirements set forth in the General NPDES
Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a
violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the
CESCL will promptly initiate the implementation of one or more of the alternative BMPs listed in
Appendix B after the first sign that existing BMPs are ineffective or failing.
List and describe BMPs:
High Visibility Plastic or Metal Fence (BMP C103)
Silt Fence (BMP C223)
Installation Schedules:
Installation will occur before all other activity.
Inspection and Maintenance plan:
Weekly
Responsible Staff:
CESCL
D.R. STRONG Consulting Engineers, Inc. Bethany Corner
Stormwater Pollution Prevention Plan Page 5
2.1.2 Element 2: Establish Construction Access
Construction access or activities occurring on unpaved areas will be minimized, yet where
necessary, access points shall be stabilized to minimize the tracking of sediment onto public
roads, and wheel washing, street sweeping, and street cleaning shall be employed to prevent
sediment from entering state waters. All wash wastewater shall be controlled on site.
Construction entrances will be installed in the location of the proposed access entrance, located
on 111th Avenue SE. Construction road and parking area stabilization will occur along this
entrance.
List and describe BMPs:
Stabilized Construction Entrance (BMP C105)
Construction Road/Parking Area Stabilization (BMP C107)
Installation Schedules:
Installation will occur after the clearing limits are marked.
Inspection and Maintenance plan:
Weekly
Responsible Staff:
CESCL
D.R. STRONG Consulting Engineers, Inc. Bethany Corner
Stormwater Pollution Prevention Plan Page 6
2.1.3 Element 3: Control Flow Rates
In order to protect the properties and waterways downstream of the project site,
stormwater discharges from the site will be controlled.
Once the detention vault is constructed, it will be utilized during construction as a flow control
and sedimentation device. Discharge from the vault will be conveyed south to the existing storm
conveyance system located in 111th Avenue SE.
Alternate flow control BMPs are included in Appendix B as a quick reference tool for the onsite
inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during
construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D).
To avoid potential erosion and sediment control issues that may cause a violation(s) of the
NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and
Sediment Control Lead will promptly initiate the implementation of one or more of the alternative
BMPs listed in Appendix B after the first sign that existing BMPs are ineffective or failing.
The project site is located west of the Cascade Mountain Crest. As such, the project must
comply with Minimum Requirement 7 (Ecology 2005).
In general, discharge rates of stormwater from the site will be controlled where increases in
impervious area or soil compaction during construction could lead to downstream erosion, or
where necessary to meet local agency stormwater discharge requirements (e.g. discharge to
combined sewer systems).
Will you construct stormwater retention and/or detention facilities?
Yes No
Will you use permanent infiltration ponds or other low impact development (example: rain
gardens, bio-retention, porous pavement) to control flow during construction?
Yes No
List and describe BMPs:
Sediment Trap (BMP C240)
Installation Schedules:
Installation will occur before any grading occurs.
Inspection and Maintenance plan:
Weekly
Responsible Staff:
CESCL
D.R. STRONG Consulting Engineers, Inc. Bethany Corner
Stormwater Pollution Prevention Plan Page 7
2.1.4 Element 4: Install Sediment Controls
Silt fence will be installed around the perimeter of the Site in areas where runoff could sheet-
flow offsite. This BMP will be installed at the start of construction.
Alternate sediment control BMPs are included in Appendix B as a quick reference tool for the
onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate
during construction to satisfy the requirements set forth in the General NPDES Permit
(Appendix D). To avoid potential erosion and sediment control issues that may cause a
violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the
Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or
more of the alternative BMPs listed in Appendix B after the first sign that existing BMPs are
ineffective or failing.
In addition, sediment will be removed from paved areas in and adjacent to construction work
areas manually or using mechanical sweepers, as needed, to minimize tracking of sediments on
vehicle tires away from the site and to minimize washoff of sediments from adjacent streets in
runoff.
Whenever possible, sediment laden water shall be discharged into onsite, relatively level,
vegetated areas (BMP C240 paragraph 5, page 4-102).
In some cases, sediment discharge in concentrated runoff can be controlled using permanent
stormwater BMPs (e.g., infiltration swales, ponds, trenches). Sediment loads can limit the
effectiveness of some permanent stormwater BMPs, such as those used for infiltration or
biofiltration; however, those BMPs designed to remove solids by settling (wet ponds or detention
ponds) can be used during the construction phase. When permanent stormwater BMPs will be
used to control sediment discharge during construction, the structure will be protected from
excessive sedimentation with adequate erosion and sediment control BMPs. Any accumulated
sediment shall be removed after construction is complete and the permanent stormwater BMP
will be restabilized with vegetation per applicable design requirements once the remainder of
the site has been stabilized.
The following BMPs will be implemented as end-of-pipe sediment controls as required to meet
permitted turbidity limits in the site discharge(s). Prior to the implementation of these
technologies, sediment sources and erosion control and soil stabilization BMP efforts will be
maximized to reduce the need for end-of-pipe sedimentation controls.
D.R. STRONG Consulting Engineers, Inc. Bethany Corner
Stormwater Pollution Prevention Plan Page 8
List and describe BMPs:
Silt Fence (BMP C233)
Interceptor Swale (BMP C200)
Storm Drain Inlet Protection (BMP C220)
Sediment Trap (BMP C240)
Installation Schedules:
These will all be installed before any grading occurs.
Inspection and Maintenance plan:
Weekly
Responsible Staff:
CESCL
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2.1.5 Element 5: Stabilize Soils
Temporary seeding and cover measures may be required for interim grading activity and at soil
stockpiles. Permanent Seeding will occur as grading is completed. All stabilized sections will
be seeded and vegetated.
Nets and Blankets along with Plastic Covering will be used on all slopes of 2:1 as shown on the
plan.
Dust Control will occur throughout the site as deemed necessary by the contractor and CESCL.
Alternate soil stabilization BMPs are included in Appendix B as a quick reference tool for the
onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate
during construction to satisfy the requirements set forth in the General NPDES Permit
(Appendix D). To avoid potential erosion and sediment control issues that may cause a
violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the
Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or
more of the alternative BMPs listed in Appendix B after the first sign that existing BMPs are
ineffective or failing.
In general, cut and fill slopes will be stabilized as soon as possible and soil stockpiles will be
temporarily covered with plastic sheeting. All stockpiled soils shall be stabilized from erosion,
protected with sediment trapping measures, and where possible, be located away from storm
drain inlets, waterways, and drainage channels.
West of the Cascade Mountains Crest
Season Dates Number of Days Soils Can
be Left Exposed
During the Dry Season May 1 – September 30 7 days
During the Wet Season October 1 – April 30 2 days
Soils must be stabilized at the end of the shift before a holiday or weekend if needed based on
the weather forecast.
Anticipated project dates: Start date: TBD End date: TBD
Will you construct during the wet season?
Yes No
List and describe BMPs:
Temporary and Permanent Seeding (BMP C120)
Nets and Blankets (BMP C122)
Plastic Covering (BMP C123)
Dust Control (BMP C140)
Installation Schedules:
These will all be installed before any grading occurs.
Inspection and Maintenance plan:
Weekly
Responsible Staff:
CESCL
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2.1.6 Element 6: Protect Slopes
Temporary slope protection measures may be required for interim grading activity and at soil
stockpiles. Permanent Seeding will occur throughout the site as slopes are stabilized.
Nets and Blankets along with Plastic Covering will be used on all slopes of 2:1
Checks Dams will be installed every 50’ as shown on the plan.
Alternate slope protection BMPs are included in Appendix B as a quick reference tool for the
onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate
during construction to satisfy the requirements set forth in the General NPDES Permit
(Appendix D). To avoid potential erosion and sediment control issues that may cause a
violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the
Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or
more of the alternative BMPs listed in Appendix B after the first sign that existing BMPs are
ineffective or failing.
Will steep slopes be present at the site during construction?
Yes No
List and describe BMPs:
Temporary and Permanent Seeding (BMP C120)
Nets and Blankets (BMP C122)
Plastic Covering (BMP C123)
Check Dams (BMP C207)
Installation Schedules:
In general, cut and fill slopes will be stabilized as soon as possible and soil stockpiles
will be temporarily covered with plastic sheeting.
Inspection and Maintenance plan:
Weekly
Responsible Staff:
CESCL
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2.1.7 Element 7: Protect Drain Inlets
All storm drain inlets and culverts made operable during construction shall be protected to
prevent unfiltered or untreated water from entering the drainage conveyance system. However,
the first priority is to keep all access roads clean of sediment and keep street wash water
separate from entering storm drains until treatment can be provided. Storm Drain Inlet
Protection (BMP C220) will be implemented for all drainage inlets and culverts that could
potentially be impacted by sediment-laden runoff on and near the project site. The following inlet
protection measures will be applied on this project:
• Storm Drain Inlet Protection (BMP C220)
There are several existing catch basins which will require filters.
If the BMP options listed above are deemed ineffective or inappropriate during construction to
satisfy the requirements set forth in the General NPDES Permit (Appendix D), or if no BMPs are
listed above but deemed necessary during construction, the Certified Erosion and Sediment
Control Lead shall implement one or more of the alternative BMP inlet protection options listed
in Appendix B.
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Stormwater Pollution Prevention Plan Page 12
2.1.8 Element 8: Stabilize Channels and Outlets
Rip Rap (BMP C209) will be provided at all outlets.
Provide stabilization, including armoring material, adequate to prevent erosion of outlets,
adjacent stream banks, slopes, and downstream reaches, will be installed at the outlets of all
conveyance systems.
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2.1.9 Element 9: Control Pollutants
All pollutants, including waste materials and demolition debris, that occur onsite shall be
handled and disposed of in a manner that does not cause contamination of stormwater. Good
housekeeping and preventative measures will be taken to ensure that the site will be kept clean,
well-organized, and free of debris. If required, BMPs to be implemented to control specific
sources of pollutants are discussed below.
Vehicles, construction equipment, and/or petroleum product storage/dispensing:
• All vehicles, equipment, and petroleum product storage/dispensing areas will be
inspected regularly to detect any leaks or spills, and to identify maintenance needs to
prevent leaks or spills.
• On-site fueling tanks and petroleum product storage containers shall include
secondary containment.
• Spill prevention measures, such as drip pans, will be used when conducting
maintenance and repair of vehicles or equipment.
• In order to perform emergency repairs on site, temporary plastic will be placed
beneath and, if raining, over the vehicle.
• Contaminated surfaces shall be cleaned immediately following any discharge or spill
incident.
Demolition:
• Dust released from demolished sidewalks, buildings, or structures will be controlled
using Dust Control measures (BMP C140).
• Storm drain inlets vulnerable to stormwater discharge carrying dust, soil, or debris
will be protected using Storm Drain Inlet Protection (BMP C220 as described above
for Element 7).
• Process water and slurry resulting from sawcutting and surfacing operations will be
prevented from entering the waters of the State by implementing Sawcutting and
Surfacing Pollution Prevention measures (BMP C152).
Concrete and grout:
• Process water and slurry resulting from concrete work will be prevented from
entering the waters of the State by implementing Concrete Handling measures (BMP
C151).
Sanitary wastewater:
• Portable sanitation facilities will be firmly secured, regularly maintained, and emptied
when necessary.
Solid Waste:
• Solid waste will be stored in secure, clearly marked containers.
Other:
• Other BMPs will be administered as necessary to address any additional pollutant
sources on site.
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Stormwater Pollution Prevention Plan Page 14
The project is not expected to exceed the 1,320 gallon stored-fuel threshold that requires
developing a Spill Prevention, Control, and Countermeasure (SPCC) Plan under the Federal
regulations of the Clean Water Act (CWA).
List and describe BMPs:
Dust Control measures (BMP C140)
Concrete Handling measures (BMP C151)
Sawcutting and Surfacing Pollution Prevention measures (BMP C152)
Storm Drain Inlet Protection (BMP C220)
Installation Schedules: Immediately following or in conjunction with activities.
Inspection and Maintenance plan:
Weekly
Responsible Staff:
CESCL
Will maintenance, fueling, and/or repair of heavy equipment and vehicles occur on-site?
Yes No
List and describe BMPs: N/A
Installation Schedules: N/A
Inspection and Maintenance plan:
Weekly
Responsible Staff:
CESCL
Will wheel wash or tire bath system BMPs be used during construction?
Yes No
List and describe BMPs: Presently not anticipated . SWPPP to be amended if wheel wash
proves necessary.
Installation Schedules: TBD
Inspection and Maintenance plan:
Weekly
Responsible Staff:
CESCL
Will pH-modifying sources be present on-site?
D.R. STRONG Consulting Engineers, Inc. Bethany Corner
Stormwater Pollution Prevention Plan Page 15
Yes No
Table 3 – pH-Modifying Sources
None
Bulk cement
Cement kiln dust
Fly ash
Other cementitious materials
New concrete washing or curing waters
Waste streams generated from concrete grinding and sawing
Exposed aggregate processes
Dewatering concrete vaults
Concrete pumping and mixer washout waters
Recycled concrete
Other (i.e., calcium lignosulfate) [please describe: ]
List and describe BMPs: Specific pH treatment measures to be determined by contractor and
CECSL. Presently, CO2 sparging or dry ice anticipated approach if pH must be altered.
Installation Schedules: prior to placement of concrete
Inspection and Maintenance plan:
Monitoring will occur at the time of concrete wash operations.
Responsible Staff:
CESCL
Concrete trucks must not be washed out onto the ground, or into storm drains, open ditches,
streets, or streams. Excess concrete must not be dumped on-site, except in designated
concrete washout areas with appropriate BMPs installed.
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2.1.10 Element 10: Control Dewatering
There will be no dewatering as part of this construction project. If excavation results in the
requirement of dewatering, this SWPPP can be modified to include dewatering measures
including control of discharge waters.
D.R. STRONG Consulting Engineers, Inc. Bethany Corner
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2.1.11 Element 11: Maintain BMPs
All temporary and permanent Erosion and Sediment Control (ESC) BMPs shall be maintained
and repaired as needed to ensure continued performance of their intended function.
Maintenance and repair shall be conducted in accordance with each particular BMP
specification (see Volume II of the SWMMWW or Chapter 7 of the SWMMEW).
Visual monitoring of all BMPs installed at the site will be conducted at least once every calendar
week and within 24 hours of any stormwater or non-stormwater discharge from the site. If the
site becomes inactive and is temporarily stabilized, the inspection frequency may be reduced to
once every calendar month.
All temporary ESC BMPs shall be removed within 30 days after final site stabilization is
achieved or after the temporary BMPs are no longer needed.
Trapped sediment shall be stabilized on-site or removed. Disturbed soil resulting from removal
of either BMPs or vegetation shall be permanently stabilized.
Additionally, protection must be provided for all BMPs installed for the permanent control of
stormwater from sediment and compaction. BMPs that are to remain in place following
completion of construction shall be examined and restored to full operating condition. If
sediment enters these BMPs during construction, the sediment shall be removed and the facility
shall be returned to conditions specified in the construction documents.
D.R. STRONG Consulting Engineers, Inc. Bethany Corner
Stormwater Pollution Prevention Plan Page 18
2.1.12 Element 12: Manage the Project
Project management will incorporate the key components listed below:
Table 5 – Management
Design the project to fit the existing topography, soils, and drainage patterns
Emphasize erosion control rather than sediment control
Minimize the extent and duration of the area exposed
Keep runoff velocities low
Retain sediment on-site
Thoroughly monitor site and maintain all ESC measures
Schedule major earthwork during the dry season
Other (please describe)
As this project site is located west of the Cascade Mountain Crest, the project will be managed
according to the following key project components:
Phasing of Construction
• The construction project is being phased to the extent practicable in order to prevent soil
erosion, and, to the maximum extent possible, the transport of sediment from the site
during construction.
• Revegetation of exposed areas and maintenance of that vegetation shall be an integral
part of the clearing activities during each phase of construction, per the Scheduling BMP
(C 162).
Seasonal Work Limitations
• From October 1 through April 30, clearing, grading, and other soil disturbing activities
shall only be permitted if shown to the satisfaction of the local permitting authority that
silt-laden runoff will be prevented from leaving the site through a combination of the
following:
o Site conditions including existing vegetative coverage, slope, soil type, and proximity
to receiving waters; and
o Limitations on activities and the extent of disturbed areas; and
o Proposed erosion and sediment control measures.
• Based on the information provided and/or local weather conditions, the local permitting
authority may expand or restrict the seasonal limitation on site disturbance.
• The following activities are exempt from the seasonal clearing and grading limitations:
o Routine maintenance and necessary repair of erosion and sediment control BMPs;
o Routine maintenance of public facilities or existing utility structures that do not
expose the soil or result in the removal of the vegetative cover to soil; and
o Activities where there is 100 percent infiltration of surface water runoff within the site
in approved and installed erosion and sediment control facilities.
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Stormwater Pollution Prevention Plan Page 19
Coordination with Utilities and Other Jurisdictions
• Care has been taken to coordinate with utilities, other construction projects, and the local
jurisdiction in preparing this SWPPP and scheduling the construction work.
Inspection and Monitoring
• All BMPs shall be inspected, maintained, and repaired as needed to assure continued
performance of their intended function. Site inspections shall be conducted by a person
who is knowledgeable in the principles and practices of erosion and sediment control.
This person has the necessary skills to:
o Assess the site conditions and construction activities that could impact the quality of
stormwater, and
o Assess the effectiveness of erosion and sediment control measures used to control
the quality of stormwater discharges.
• A Certified Erosion and Sediment Control Lead shall be on-site or on-call at all times.
• Whenever inspection and/or monitoring reveals that the BMPs identified in this SWPPP
are inadequate, due to the actual discharge of or potential to discharge a significant
amount of any pollutant, appropriate BMPs or design changes shall be implemented as
soon as possible.
Maintaining an Updated Construction SWPPP
• This SWPPP shall be retained on-site or within reasonable access to the site.
• The SWPPP shall be modified whenever there is a change in the design, construction,
operation, or maintenance at the construction site that has, or could have, a significant
effect on the discharge of pollutants to waters of the state.
• The SWPPP shall be modified if, during inspections or investigations conducted by the
owner/operator, or the applicable local or state regulatory authority, it is determined that
the SWPPP is ineffective in eliminating or significantly minimizing pollutants in
stormwater discharges from the site. The SWPPP shall be modified as necessary to
include additional or modified BMPs designed to correct problems identified. Revisions
to the SWPPP shall be completed within seven (7) days following the inspection.
• If BMP(s) are deemed do not satisfy the requirements set forth in the General NPDES
Permit (Appendix D), the CESCL will promptly implement one or more of the alternative
BMPs listed in Appendix B after the first sign that existing BMPs are ineffective or failing.
• Site inspections and monitoring will be conducted in accordance with Special Condition
S4 of the CSWGP. Sampling will occur at the baker tank discharge piping.
• The SWPPP will be updated, maintained, and implemented in accordance with Special
Conditions S3, S4, and S9 of the CSWGP.
• As site work progresses the SWPPP will be modified routinely to reflect changing site
conditions. The SWPPP will be reviewed monthly to ensure the content is current.
• Upon request, contractor shall provide the DOE and City of Sammamish with current
SWPPP.
D.R. STRONG Consulting Engineers, Inc. Bethany Corner
Stormwater Pollution Prevention Plan Page 20
3 Pollution Prevention Team
Table 7 – Team Information
Title Name(s) Phone Number
Certified Erosion and
Sediment Control Lead
(CESCL)
Associated Earth Sciences, Inc. 425.827.7701
Resident Engineer Jonathan S. Murray, PE 425-827-3063
Emergency Ecology
Contact
Howard Zorzi 425-649-7130
Emergency Permittee/
Owner Contact
Mark Seek 206-315-8130
Non-Emergency Owner
Contact
Mark Seek 206-315-8130
Monitoring Personnel Associated Earth Sciences, Inc. 425.827.7701
Ecology Regional Office Northwest Regional Office 425-649-7000
City Spill Hotline (8:00 am to
5:00 pm)
425-295-0500
King County Spill Hotline
(After Hours)
206-296-8100
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Stormwater Pollution Prevention Plan Page 21
4 Monitoring and Sampling Requirements
Monitoring includes visual inspection, sampling for water quality parameters of concern, and
documentation of the inspection and sampling findings in a site log book. A site log book will be
maintained for all on-site construction activities and will include:
• A record of the implementation of the SWPPP and other permit requirements
• Site inspections
• Stormwater sampling data
File a blank form under Appendix D.
The site log book must be maintained on-site within reasonable access to the site and be made
available upon request to Ecology or the local jurisdiction.
Numeric effluent limits may be required for certain discharges to 303(d) listed waterbodies. See
CSWGP Special Condition S8 and Section 5 of this template.
4.1 Site Inspection
All BMPs will be inspected, maintained, and repaired as needed to assure continued
performance of their intended function. The inspector will be a Certified Erosion and Sediment
Control Lead (CESCL) per BMP C160. The name and contact information for the CESCL is
provided in Section 3 of this SWPPP.
Site inspection will occur in all areas disturbed by construction activities and at all stormwater
discharge points. Stormwater will be examined for the presence of suspended sediment,
turbidity, discoloration, and oily sheen. The site inspector will evaluate and document the
effectiveness of the installed BMPs and determine if it is necessary to repair or replace any of
the BMPs to improve the quality of stormwater discharges. All maintenance and repairs will be
documented in the site log book or forms provided in this document. All new BMPs or design
changes will be documented in the SWPPP as soon as possible.
Site inspections will be conducted at least once every calendar week and within 24 hours
following any discharge from the site. For sites that are temporarily stabilized and inactive, the
required frequency is reduced to once per calendar month.
The site inspector will record each site inspection using the site log inspection forms provided in
Appendix E. The site inspection log forms may be separated from this SWPPP document, but
will be maintained on-site or within reasonable access to the site and be made available upon
request to Ecology or the local jurisdiction.
4.2 Stormwater Quality Sampling
Runoff will be collected and conveyed to the proposed vault, followed by a StormFilter media
filtration system to meet Enhanced Water Quality requirements. Testing will occur as deemed
necessary by the CESCL.
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4.2.1 Turbidity Sampling
Requirements include calibrated turbidity meter or transparency tube to sample site discharges
for compliance with the CSWGP. Sampling will be conducted at all discharge points at least
once per calendar week.
Method for sampling turbidity:
Table 8 – Turbidity Sampling Method
Turbidity Meter/Turbidimeter (required for disturbances 5 acres or greater in size)
Transparency Tube (option for disturbances less than 1 acre and up to 5 acres in size)
The benchmark for turbidity value is 25 nephelometric turbidity units (NTU) and a transparency
less than 33 centimeters.
If the discharge’s turbidity is 26 to 249 NTU or the transparency is less than 33 cm but equal to
or greater than 6 cm, the following steps will be conducted:
1. Review the SWPPP for compliance with Special Condition S9. Make appropriate
revisions within 7 days of the date the discharge exceeded the benchmark.
2. Immediately begin the process to fully implement and maintain appropriate source
control and/or treatment BMPs as soon as possible. Address the problems within 10
days of the date the discharge exceeded the benchmark. If installation of necessary
treatment BMPs is not feasible within 10 days, Ecology may approve additional time
when the Permittee requests an extension within the initial 10-day response period.
3. Document BMP implementation and maintenance in the site log book.
If the turbidity exceeds 250 NTU or the transparency is 6 cm or less at any time, the following
steps will be conducted:
1. Telephone the applicable Ecology Region’s Environmental Report Tracking System
(ERTS) number within 24 hours.
• Central Region (Benton, Chelan, Douglas, Kittitas, Klickitat, Okanogan,
Yakima): (509) 575-2490
• Eastern Region (Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant,
Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, Whitman): (509) 329-3400
• Northwest Region (King, Kitsap, Island, San Juan, Skagit, Snohomish,
Whatcom): (425) 649-7000
• Southwest Region (Clallam, Clark, Cowlitz, Grays Harbor, Jefferson, Lewis,
Mason, Pacific, Pierce, Skamania, Thurston, Wahkiakum,): (360) 407-6300
2. Immediately begin the process to fully implement and maintain appropriate source
control and/or treatment BMPs as soon as possible. Address the problems within 10
days of the date the discharge exceeded the benchmark. If installation of necessary
treatment BMPs is not feasible within 10 days, Ecology may approve additional time
when the Permittee requests an extension within the initial 10-day response period
3. Document BMP implementation and maintenance in the site log book.
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4. Continue to sample discharges daily until one of the following is true:
• Turbidity is 25 NTU (or lower).
• Transparency is 33 cm (or greater).
• Compliance with the water quality limit for turbidity is achieved.
o 1 - 5 NTU over background turbidity, if background is less than 50 NTU
o 1% - 10% over background turbidity, if background is 50 NTU or greater
• The discharge stops or is eliminated.
4.2.2 pH Sampling
pH monitoring is required for “Significant concrete work” (i.e., greater than 1000 cubic yards
poured or recycled concrete over the life of the project). The use of engineered soils (soil
amendments including but not limited to Portland cement-treated base [CTB], cement kiln dust
[CKD] or fly ash) also requires pH monitoring.
For significant concrete work, pH sampling will start the first day concrete is poured and
continue until it is cured, typically three (3) weeks after the last pour.
For engineered soils, pH sampling begins when engineered soils are first exposed to
precipitation and continues until the area is fully stabilized.
If the measured pH is 8.5 or greater, the following measures will be taken:
1. Prevent high pH water from entering storm sewer systems or surface water.
2. Adjust or neutralize the high pH water to the range of 6.5 to 8.5 su using appropriate
technology such as carbon dioxide (CO2) sparging (liquid or dry ice).
3. Written approval will be obtained from Ecology prior to the use of chemical treatment
other than CO2 sparging or dry ice.
Method for sampling pH:
Table 9 – pH Sampling Method
pH meter
pH test kit
Wide range pH indicator paper
Not: pH monitoring equipment unknown at this time; to be determined by CESCL
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Stormwater Pollution Prevention Plan Page 24
5 Discharges to 303(d) or Total Maximum Daily Load (TMDL)
Waterbodies
5.1 303(d) Listed Waterbodies
Is the receiving water 303(d) (Category 5) listed for turbidity, fine sediment, phosphorus, or pH?
Yes No
List the impairment(s):
Green River - pH
5.2 TMDL Waterbodies
Waste Load Allocation for CWSGP discharges:
List and describe BMPs:
Discharges to TMDL receiving waterbodies will meet in-stream water quality criteria at the point
of discharge.
The Construction Stormwater General Permit Proposed New Discharge to an Impaired Water
Body form is included in Appendix F.
D.R. STRONG Consulting Engineers, Inc. Bethany Corner
Stormwater Pollution Prevention Plan Page 25
6 Reporting and Record Keeping
6.1 Record Keeping
6.1.1 Site Log Book
A site log book will be maintained for all on-site construction activities and will include:
• A record of the implementation of the SWPPP and other permit requirements
• Site inspections
• Sample logs
6.1.2 Records Retention
Records will be retained during the life of the project and for a minimum of three (3) years
following the termination of permit coverage in accordance with Special Condition S5.C of the
CSWGP.
Permit documentation to be retained on-site:
• CSWGP
• Permit Coverage Letter
• SWPPP
• Site Log Book
Permit documentation will be provided within 14 days of receipt of a written request from
Ecology. A copy of the SWPPP or access to the SWPPP will be provided to the public when
requested in writing in accordance with Special Condition S5.G.2.b of the CSWGP.
6.1.3 Updating the SWPPP
The SWPPP will be modified if:
• Found ineffective in eliminating or significantly minimizing pollutants in stormwater
discharges from the site.
• There is a change in design, construction, operation, or maintenance at the construction
site that has, or could have, a significant effect on the discharge of pollutants to waters
of the State.
The SWPPP will be modified within seven (7) days if inspection(s) or investigation(s) determine
additional or modified BMPs are necessary for compliance. An updated timeline for BMP
implementation will be prepared.
6.2 Reporting
6.2.1 Discharge Monitoring Reports
Cumulative soil disturbance is one (1) acre or larger; therefore, Discharge Monitoring
Reports (DMRs) will be submitted to Ecology monthly. If there was no discharge during a given
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Stormwater Pollution Prevention Plan Page 26
monitoring period the DMR will be submitted as required, reporting “No Discharge”. The DMR
due date is fifteen (15) days following the end of each calendar month.
DMRs will be reported online through Ecology’s WQWebDMR System.
6.2.2 Notification of Noncompliance
If any of the terms and conditions of the permit is not met, and the resulting noncompliance may
cause a threat to human health or the environment, the following actions will be taken:
1. Ecology will be immediately notified of the failure to comply by calling the applicable
Regional office ERTS phone number (Regional office numbers listed below).
2. Immediate action will be taken to prevent the discharge/pollution or otherwise stop or
correct the noncompliance. If applicable, sampling and analysis of any noncompliance
will be repeated immediately and the results submitted to Ecology within five (5) days of
becoming aware of the violation.
3. A detailed written report describing the noncompliance will be submitted to Ecology
within five (5) days, unless requested earlier by Ecology.
Anytime turbidity sampling indicates turbidity is 250 NTUs or greater, or water transparency is 6
cm or less, the Ecology Regional office will be notified by phone within 24 hours of analysis as
required by Special Condition S5.A of the CSWGP.
• Central Region at (509) 575-2490 for Benton, Chelan, Douglas, Kittitas, Klickitat,
Okanogan, or Yakima County
• Eastern Region at (509) 329-3400 for Adams, Asotin, Columbia, Ferry, Franklin,
Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, or Whitman
County
• Northwest Region at (425) 649-7000 for Island, King, Kitsap, San Juan, Skagit,
Snohomish, or Whatcom County
• Southwest Region at (360) 407-6300 for Clallam, Clark, Cowlitz, Grays Harbor,
Jefferson, Lewis, Mason, Pacific, Pierce, Skamania, Thurston, or Wahkiakum
Include the following information:
1. Your name and / Phone number
2. Permit number
3. City / County of project
4. Sample results
5. Date / Time of call
6. Date / Time of sample
7. Project name
In accordance with Special Condition S4.D.5.b of the CSWGP, the Ecology Regional office will
be notified if chemical treatment other than CO2 sparging is planned for adjustment of high pH
water.
D.R. STRONG Consulting Engineers, Inc. Alpine Nursery
Stormwater Pollution Prevention Plan Page A-1
Appendix A
Site Map
GRAPHIC SCALE02040 80
1 INCH = 40 FT.
BY:Date:
RECOMMENDED FOR APPOVAL
BY:
BY:
BY:
Date:
Date:
Date:
BY:Date:
RECOMMENDED FOR APPOVAL
BY:
BY:
BY:
Date:
Date:
Date:
GRAPHIC SCALE
0 15 30 60
1 INCH = 30 FT.
BY:Date:
RECOMMENDED FOR APPOVAL
BY:
BY:
BY:
Date:
Date:
Date:
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Stormwater Pollution Prevention Plan Page B-1
Appendix B
BMP Details
D.R. STRONG Consulting Engineers, Inc. Alpine Nursery
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Appendix C
Correspondence
None at this time.
D.R. STRONG Consulting Engineers, Inc. Alpine Nursery
Stormwater Pollution Prevention Plan Page D-1
Appendix D
Site Inspection Form
The results of each inspection shall be summarized in an inspection report or checklist that is
entered into or attached to the site log book. It is suggested that the inspection report or
checklist be included in this appendix to keep monitoring and inspection information in one
document, but this is optional. However, it is mandatory that this SWPPP and the site
inspection forms be kept onsite at all times during construction, and that inspections be
performed and documented as outlined below.
At a minimum, each inspection report or checklist shall include:
Inspection date/times
Weather information: general conditions during inspection, approximate amount of
precipitation since the last inspection, and approximate amount of precipitation within the last 24
hours.
A summary or list of all BMPs that have been implemented, including observations of all
erosion/sediment control structures or practices.
The following shall be noted:
locations of BMPs inspected,
locations of BMPs that need maintenance,
the reason maintenance is needed,
locations of BMPs that failed to operate as designed or intended, and
locations where additional or different BMPs are needed, and the reason(s) why
A description of stormwater discharged from the site. The presence of suspended sediment,
turbid water, discoloration, and/or oil sheen shall be noted, as applicable.
A description of any water quality monitoring performed during inspection, and the results of that
monitoring.
General comments and notes, including a brief description of any BMP repairs, maintenance or
installations made as a result of the inspection.
A statement that, in the judgment of the person conducting the site inspection, the site is either
in compliance or out of compliance with the terms and conditions of the SWPPP and the
NPDES permit. If the site inspection indicates that the site is out of compliance, the inspection
report shall include a summary of the remedial actions required to bring the site back into
compliance, as well as a schedule of implementation.
D.R. STRONG Consulting Engineers, Inc. Alpine Nursery
Stormwater Pollution Prevention Plan Page D-2
Name, title, and signature of person conducting the site inspection; and the following statement:
“I certify under penalty of law that this report is true, accurate, and complete, to the best of my
knowledge and belief”.
When the site inspection indicates that the site is not in compliance with any terms and
conditions of the NPDES permit, the Permittee shall take immediate action(s) to: stop, contain,
and clean up the unauthorized discharges, or otherwise stop the noncompliance; correct the
problem(s); implement appropriate Best Management Practices (BMPs), and/or conduct
maintenance of existing BMPs; and achieve compliance with all applicable standards and permit
conditions. In addition, if the noncompliance causes a threat to human health or the
environment, the Permittee shall comply with the Noncompliance Notification requirements in
Special Condition S5.F of the permit.
Construction Stormwater Site Inspection Form
D.R. STRONG Consulting Engineers, Inc. Alpine Nursery
Stormwater Pollution Prevention Plan Page D-3
Project Name Permit #: Date: Time:
Name of Certified Erosion Sediment Control Lead (CESCL) or qualified inspector if less than one acre
Print Name:
Approximate rainfall amount since the last inspection (in inches):
Approximate rainfall amount in the last 24 hours (in inches):
Current Weather Clear Cloudy Mist Rain Wind Fog
A. Type of inspection: Weekly Post Storm Event Other
B. Phase of Active Construction (check all that apply):
Pre Construction/installation of erosion/sediment controls Clearing/Demo/Grading Infrastructure/storm/roads
Concrete pours Vertical Construction/buildings Utilities
Offsite improvements Site temporary stabilized Final stabilization
C. Questions:
1. Were all areas of construction and discharge points inspected? Yes No
2. Did you observe the presence of suspended sediment, turbidity, discoloration, or oil sheen Yes No
3. Was a water quality sample taken during inspection? (refer to permit conditions S4 & S5) Yes No
4. Was there a turbid discharge 250 NTU or greater, or Transparency 6 cm or less?* Yes No
5. If yes to #4 was it reported to Ecology? Yes No
6. Is pH sampling required? pH range required is 6.5 to 8.5. Yes No
If answering yes to a discharge, describe the event. Include when, where, and why it happened; what action was taken,
and when.
*If answering yes to # 4 record NTU/Transparency with continual sampling daily until turbidity is 25 NTU or less/
transparency is 33 cm or greater.
Sampling Results: Date:
Parameter Method (circle one) Result Other/Note
NTU cm pH
Turbidity tube, meter, laboratory
pH Paper, kit, meter
Construction Stormwater Site Inspection Form
D.R. STRONG Consulting Engineers, Inc. Alpine Nursery
Stormwater Pollution Prevention Plan Page D-4
D. Check the observed status of all items. Provide “Action Required “details and dates.
Element # Inspection BMPs
Inspected
BMP needs
maintenance
BMP
failed
Action required
(describe in
section F) yes no n/a
1
Clearing
Limits
Before beginning land disturbing
activities are all clearing limits, natural
resource areas (streams, wetlands,
buffers, trees) protected with barriers
or similar BMPs? (high visibility
recommended)
2
Construction
Access
Construction access is stabilized with
quarry spalls or equivalent BMP to
prevent sediment from being tracked
onto roads?
Sediment tracked onto the road way
was cleaned thoroughly at the end of
the day or more frequent as necessary.
3
Control Flow
Rates
Are flow control measures installed to
control stormwater volumes and
velocity during construction and do
they protect downstream properties
and waterways from erosion?
If permanent infiltration ponds are
used for flow control during
construction, are they protected from
siltation?
4
Sediment
Controls
All perimeter sediment controls (e.g.
silt fence, wattles, compost socks,
berms, etc.) installed, and maintained
in accordance with the Stormwater
Pollution Prevention Plan (SWPPP).
Sediment control BMPs (sediment
ponds, traps, filters etc.) have been
constructed and functional as the first
step of grading.
Stormwater runoff from disturbed
areas is directed to sediment removal
BMP.
5
Stabilize Soils
Have exposed un-worked soils been
stabilized with effective BMP to
prevent erosion and sediment
deposition?
Are stockpiles stabilized from erosion,
protected with sediment trapping
measures and located away from drain
inlet, waterways, and drainage
channels?
Have soils been stabilized at the end of
the shift, before a holiday or weekend
if needed based on the weather
forecast?
Construction Stormwater Site Inspection Form
D.R. STRONG Consulting Engineers, Inc. Alpine Nursery
Stormwater Pollution Prevention Plan Page D-5
Element # Inspection BMPs Inspected BMP needs
maintenance
BMP
failed
Action required
(describe in
section F) yes no n/a
6
Protect
Slopes
Has stormwater and ground water
been diverted away from slopes and
disturbed areas with interceptor dikes,
pipes and or swales?
Is off-site storm water managed
separately from stormwater generated
on the site?
Is excavated material placed on uphill
side of trenches consistent with safety
and space considerations?
Have check dams been placed at
regular intervals within constructed
channels that are cut down a slope?
7
Drain Inlets
Storm drain inlets made operable
during construction are protected.
Are existing storm drains within the
influence of the project protected?
8
Stabilize
Channel and
Outlets
Have all on-site conveyance channels
been designed, constructed and
stabilized to prevent erosion from
expected peak flows?
Is stabilization, including armoring
material, adequate to prevent erosion
of outlets, adjacent stream banks,
slopes and downstream conveyance
systems?
9
Control
Pollutants
Are waste materials and demolition
debris handled and disposed of to
prevent contamination of stormwater?
Has cover been provided for all
chemicals, liquid products, petroleum
products, and other material?
Has secondary containment been
provided capable of containing 110%
of the volume?
Were contaminated surfaces cleaned
immediately after a spill incident?
Were BMPs used to prevent
contamination of stormwater by a pH
modifying sources?
Wheel wash wastewater is handled
and disposed of properly.
10
Control
Dewatering
Concrete washout in designated areas.
No washout or excess concrete on the
ground.
Dewatering has been done to an
approved source and in compliance
with the SWPPP.
Were there any clean non turbid
dewatering discharges?
Construction Stormwater Site Inspection Form
D.R. STRONG Consulting Engineers, Inc. Alpine Nursery
Stormwater Pollution Prevention Plan Page D-6
Element # Inspection BMPs Inspected BMP needs
maintenance
BMP
failed
Action required
(describe in
section F)
yes no n/a
11
Maintain
BMP
Are all temporary and permanent
erosion and sediment control BMPs
maintained to perform as intended?
12
Manage the
Project
Has the project been phased to the
maximum degree practicable?
Has regular inspection, monitoring and
maintenance been performed as
required by the permit?
Has the SWPPP been updated,
implemented and records maintained?
E. Check all areas that have been inspected.
All in place BMPs All discharge locations All concrete wash out areas All construction
entrances/exits
All disturbed soils All material storage areas All equipment storage areas
F. Elements checked “Action Required” (section D) describe corrective action to be taken. List the element number;
be specific on location and work needed. Document, initial, and date when the corrective action has been completed
and inspected.
Element
#
Description and Location Action Required Completion
Date
Initials
Attach additional page if needed
Sign the following certification:
“I certify that this report is true, accurate, and complete, to the best of my knowledge and belief”
Inspected by:
Print Signature
Title/Qualification of Inspector Date
D.R. STRONG Consulting Engineers, Inc. Alpine Nursery
Stormwater Pollution Prevention Plan Page F-2
Appendix E
Construction Stormwater General Permit (CSWGP)
D.R. STRONG Consulting Engineers, Inc. Alpine Nursery
Stormwater Pollution Prevention Plan Page F-2
Appendix F
Engineering Calculations
Existing Site Hydrology
KCRTS was used to model the peak runoff from the Site. Per Table 3.2.2.b of the Manual the
soil type is modeled as “Till” for the Alderwood gravelly sandy loam SCS classification. The
entire Site is modeled as “Forest.” Results of the KCRTS analysis are included in this section.
Flow Frequency Analysis
Time Series File:predev.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) Period
0.131 2 2/09/01 18:00 0.176 1 100.00 0.990
0.042 7 1/05/02 16:00 0.131 2 25.00 0.960
0.103 3 2/28/03 3:00 0.103 3 10.00 0.900
0.012 8 8/26/04 2:00 0.103 4 5.00 0.800
0.061 6 1/05/05 8:00 0.091 5 3.00 0.667
0.103 4 1/18/06 20:00 0.061 6 2.00 0.500
0.091 5 11/24/06 4:00 0.042 7 1.30 0.231
0.176 1 1/09/08 9:00 0.012 8 1.10 0.091
Computed Peaks 0.161 50.00 0.980
The maximum discharge of the construction stormwater will not exceed 50% of the 2-year
predeveloped peak flow rate of 0.061 cfs. Therefore the max discharge from the Site during
construction will not exceed 0.0305 cfs.
D.R. STRONG Consulting Engineers, Inc. Alpine Nursery
Stormwater Pollution Prevention Plan Page F-2
Flow Frequency Analysis
Time Series File:rdin_15.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) Period
0.557 6 8/27/01 18:00 1.72 1 100.00 0.990
0.396 8 1/05/02 15:00 1.20 2 25.00 0.960
1.20 2 12/08/02 17:15 0.778 3 10.00 0.900
0.449 7 8/23/04 14:30 0.690 4 5.00 0.800
0.690 4 11/17/04 5:00 0.668 5 3.00 0.667
0.668 5 10/27/05 10:45 0.557 6 2.00 0.500
0.778 3 10/25/06 22:45 0.449 7 1.30 0.231
1.72 1 1/09/08 6:30 0.396 8 1.10 0.091
Computed Peaks 1.55 50.00 0.980
Sediment Trap Facility Sizing
The Site will utilize one sediment trap for sediment control. The maximum discharge rate for the
site is 0.031 cfs (50% of the 2-year predeveloped peak).
The sediment traps will discharge to the collection system on 111th AVE SE.
Below is sizing summary:
Sediment Trap basin: 1.85 acres
2-year peak flow rate: 0.557 cfs
Required Surface Area: 1,159 s.f.
Provided Surface Area: 1,700 s.f.
2016 D. R. STRONG Consulting Engineers Inc. Page 72 Bethany Corner
Technical Information Report Renton, Washington
APPENDIX “C” BOND QUANTITY WORKSHEET
Planning Division |1055 South Grady Way – 6 th Floor | Renton, WA 98057 (425) 430-7200
Date Prepared:
Name:
PE Registration No:
Firm Name:
Firm Address:
Phone No.
Email Address:
Project Name: Project Owner:
CED Plan # (LUA):Phone:
CED Permit # (U):Address:
Site Address:
Street Intersection:Addt'l Project Owner:
Parcel #(s):Phone:
Address:
Clearing and grading greater than or equal to 5,000 board feet of timber?
Yes/No:NO Water Service Provided by:
If Yes, Provide Forest Practice Permit #:Sewer Service Provided by:
9102 SE 41st StAbbreviated Legal
Description:
LOTS 11 AND 12, BLOCK 7, AKER'S FARMS NO. 6, ACCORDING TO THE
PLAT THEREOF RECORDED IN VOLUME 42 OF PLATS, PAGE 15,
RECORDS OF KING COUNTY, WASHINGTON
SITUATE IN THE COUNTY OF KING, STATE OF WASHINGTON.
Mercer Island, WA 98040
16433 & 16451 111th Ave SE
15233 Manion Way NE
Mary Nguyn111th Ave SE and SE 164th St
########
(425) 919-4062
12/14/2016
Prepared by:
FOR APPROVALProject Phase 1
jonathan.murray@drstrong.com
Jonathan S. Murray, P.E.
50096
D.R. STRONG Consulting Engineers, Inc.
620 7th Avenue, Kirkland, WA 98033
(425) 827-3063
SITE IMPROVEMENT BOND QUANTITY WORKSHEET
PROJECT INFORMATION
SOOS CREEK WATER & SEWER
SOOS CREEK WATER & SEWER
1 Select the current project status/phase from the following options:
For Approval - Preliminary Data Enclosed, pending approval from the City;
For Construction - Estimated Data Enclosed, Plans have been approved for contruction by the City;
Project Closeout - Final Costs and Quantities Enclosed for Project Close-out Submittal
Engineer Stamp Required
(all cost estimates must have original wet stamp and signature)
Clearing and Grading Utility Providers
N/A
Project Location and Description Project Owner Information
Bethany Corner
Duval, WA 98019
008800-0560, -0570
Mark Seek
##-######
Page 1 of 1
Ref 8-H Bond Quantity Worksheet SECTION I PROJECT INFORMATION
Unit Prices Updated: 06/14/2016
Version: 06/14/2016
Printed 12/15/2016
CED Permit #:########
Unit
Reference #Price Unit Quantity Cost
Backfill & compaction-embankment ESC-1 6.50$ CY 10000 65,000.00
Check dams, 4" minus rock ESC-2 SWDM 5.4.6.3 80.00$ Each 19 1,520.00
Catch Basin Protection ESC-3 35.50$ Each 11 390.50
Crushed surfacing 1 1/4" minus ESC-4 WSDOT 9-03.9(3)95.00$ CY
Ditching ESC-5 9.00$ CY
Excavation-bulk ESC-6 2.00$ CY
Fence, silt ESC-7 SWDM 5.4.3.1 1.50$ LF 965 1,447.50
Fence, Temporary (NGPE)ESC-8 1.50$ LF
Geotextile Fabric ESC-9 2.50$ SY
Hay Bale Silt Trap ESC-10 0.50$ Each
Hydroseeding ESC-11 SWDM 5.4.2.4 0.80$ SY 6500 5,200.00
Interceptor Swale / Dike ESC-12 1.00$ LF 1000 1,000.00
Jute Mesh ESC-13 SWDM 5.4.2.2 3.50$ SY
Level Spreader ESC-14 1.75$ LF
Mulch, by hand, straw, 3" deep ESC-15 SWDM 5.4.2.1 2.50$ SY
Mulch, by machine, straw, 2" deep ESC-16 SWDM 5.4.2.1 2.00$ SY 6500 13,000.00
Piping, temporary, CPP, 6"ESC-17 12.00$ LF
Piping, temporary, CPP, 8"ESC-18 14.00$ LF
Piping, temporary, CPP, 12"ESC-19 18.00$ LF 54 972.00
Plastic covering, 6mm thick, sandbagged ESC-20 SWDM 5.4.2.3 4.00$ SY
Rip Rap, machine placed; slopes ESC-21 WSDOT 9-13.1(2)45.00$ CY 10 450.00
Rock Construction Entrance, 50'x15'x1'ESC-22 SWDM 5.4.4.1 1,800.00$ Each
Rock Construction Entrance, 100'x15'x1'ESC-23 SWDM 5.4.4.1 3,200.00$ Each 1 3,200.00
Sediment pond riser assembly ESC-24 SWDM 5.4.5.2 2,200.00$ Each
Sediment trap, 5' high berm ESC-25 SWDM 5.4.5.1 19.00$ LF
Sed. trap, 5' high, riprapped spillway berm section ESC-26 SWDM 5.4.5.1 70.00$ LF
Seeding, by hand ESC-27 SWDM 5.4.2.4 1.00$ SY
Sodding, 1" deep, level ground ESC-28 SWDM 5.4.2.5 8.00$ SY
Sodding, 1" deep, sloped ground ESC-29 SWDM 5.4.2.5 10.00$ SY
TESC Supervisor ESC-30 110.00$ HR 16 1,760.00
Water truck, dust control ESC-31 SWDM 5.4.7 140.00$ HR 16 2,240.00
Unit
Reference #Price Unit Quantity Cost
250.00$ Each 1 250.00
EROSION/SEDIMENT SUBTOTAL:96,430.00
SALES TAX @ 9.5%9,160.85
EROSION/SEDIMENT TOTAL:105,590.85
(A)
SITE IMPROVEMENT BOND QUANTITY WORKSHEET
FOR EROSION & SEDIMENT CONTROL
Description No.
(A)
Sump Pump
WRITE-IN-ITEMS
Page 1 of 1
Ref 8-H Bond Quantity Worksheet SECTION II.a EROSION_CONTROL
Unit Prices Updated: 06/14/2016
Version: 06/14/2016
Printed 12/15/2016
CED Permit #:########
Existing Future Public Private
Right-of-Way Improvements Improvements
(D) (E)
Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost
GENERAL ITEMS
Backfill & Compaction- embankment GI-1 6.00$ CY 2990 17,940.00 6973 41,838.00
Backfill & Compaction- trench GI-2 9.00$ CY 115 1,035.00 470 4,230.00
Clear/Remove Brush, by hand (SY)GI-3 1.00$ SY
Bollards - fixed GI-4 240.74$ Each
Bollards - removable GI-5 452.34$ Each
Clearing/Grubbing/Tree Removal GI-6 10,000.00$ Acre 0.3 3,000.00 1.5 15,000.00
Excavation - bulk GI-7 2.00$ CY 3000 6,000.00
Excavation - Trench GI-8 5.00$ CY 115 575.00 470 2,350.00
Fencing, cedar, 6' high GI-9 20.00$ LF
Fencing, chain link, 4'GI-10 38.31$ LF
Fencing, chain link, vinyl coated, 6' high GI-11 20.00$ LF
Fencing, chain link, gate, vinyl coated, 20' GI-12 1,400.00$ Each
Fill & compact - common barrow GI-13 25.00$ CY
Fill & compact - gravel base GI-14 27.00$ CY
Fill & compact - screened topsoil GI-15 39.00$ CY
Gabion, 12" deep, stone filled mesh GI-16 65.00$ SY
Gabion, 18" deep, stone filled mesh GI-17 90.00$ SY
Gabion, 36" deep, stone filled mesh GI-18 150.00$ SY
Grading, fine, by hand GI-19 2.50$ SY
Grading, fine, with grader GI-20 2.00$ SY
Monuments, 3' Long GI-21 250.00$ Each 1 250.00
Sensitive Areas Sign GI-22 7.00$ Each
Sodding, 1" deep, sloped ground GI-23 8.00$ SY
Surveying, line & grade GI-24 850.00$ Day 2 1,700.00 2 1,700.00
Surveying, lot location/lines GI-25 1,800.00$ Acre 0.3 540.00 1.5 2,700.00
Topsoil Type A (imported)GI-26 28.50$ CY
Traffic control crew ( 2 flaggers )GI-27 120.00$ HR
Trail, 4" chipped wood GI-28 8.00$ SY
Trail, 4" crushed cinder GI-29 9.00$ SY
Trail, 4" top course GI-30 12.00$ SY
Conduit, 2"GI-31 5.00$ LF
Wall, retaining, concrete GI-32 55.00$ SF
Wall, rockery GI-33 15.00$ SF
SUBTOTAL THIS PAGE:250.00 24,790.00 73,818.00
(B)(C)(D)(E)
SITE IMPROVEMENT BOND QUANTITY WORKSHEET
FOR STREET AND SITE IMPROVEMENTS
Quantity Remaining
(Bond Reduction)
(B)(C)
Page 1 of 3
Ref 8-H Bond Quantity Worksheet SECTION II.b TRANSPORTATION
Unit Prices Updated: 06/14/2016
Version: 06/14/2016
Printed 12/15/2016
CED Permit #:########
Existing Future Public Private
Right-of-Way Improvements Improvements
(D) (E)
Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost
SITE IMPROVEMENT BOND QUANTITY WORKSHEET
FOR STREET AND SITE IMPROVEMENTS
Quantity Remaining
(Bond Reduction)
(B)(C)
ROAD IMPROVEMENT/PAVEMENT/SURFACING
AC Grinding, 4' wide machine < 1000sy RI-1 30.00$ SY
AC Grinding, 4' wide machine 1000-2000sy RI-2 16.00$ SY
AC Grinding, 4' wide machine > 2000sy RI-3 10.00$ SY
AC Removal/Disposal RI-4 35.00$ SY
Barricade, Type III ( Permanent )RI-5 56.00$ LF
Guard Rail RI-6 30.00$ LF
Curb & Gutter, rolled RI-7 17.00$ LF
Curb & Gutter, vertical RI-8 12.50$ LF 275 3,437.50 516 6,450.00
Curb and Gutter, demolition and disposal RI-9 18.00$ LF
Curb, extruded asphalt RI-10 5.50$ LF
Curb, extruded concrete RI-11 7.00$ LF
Sawcut, asphalt, 3" depth RI-12 1.85$ LF 425 786.25
Sawcut, concrete, per 1" depth RI-13 3.00$ LF
Sealant, asphalt RI-14 2.00$ LF 425 850.00
Shoulder, gravel, 4" thick RI-15 15.00$ SY
Sidewalk, 4" thick RI-16 38.00$ SY 152 5,776.00 287 10,906.00
Sidewalk, 4" thick, demolition and disposal RI-17 32.00$ SY
Sidewalk, 5" thick RI-18 41.00$ SY
Sidewalk, 5" thick, demolition and disposal RI-19 40.00$ SY
Sign, Handicap RI-20 85.00$ Each
Striping, per stall RI-21 7.00$ Each
Striping, thermoplastic, ( for crosswalk )RI-22 3.00$ SF
Striping, 4" reflectorized line RI-23 0.50$ LF
Additional 2.5" Crushed Surfacing RI-24 3.60$ SY
HMA 1/2" Overlay 1.5" RI-25 14.00$ SY
HMA 1/2" Overlay 2"RI-26 18.00$ SY 375 6,750.00
HMA Road, 2", 4" rock, First 2500 SY RI-27 28.00$ SY
HMA Road, 2", 4" rock, Qty. over 2500SY RI-28 21.00$ SY
HMA Road, 4", 6" rock, First 2500 SY RI-29 45.00$ SY 120 5,400.00 685 30,825.00
HMA Road, 4", 6" rock, Qty. over 2500 SY RI-30 37.00$ SY
HMA Road, 4", 4.5" ATB RI-31 38.00$ SY
Gravel Road, 4" rock, First 2500 SY RI-32 15.00$ SY
Gravel Road, 4" rock, Qty. over 2500 SY RI-33 10.00$ SY
Thickened Edge RI-34 8.60$ LF
SUBTOTAL THIS PAGE:22,999.75 48,181.00
(B)(C)(D)(E)
Page 2 of 3
Ref 8-H Bond Quantity Worksheet SECTION II.b TRANSPORTATION
Unit Prices Updated: 06/14/2016
Version: 06/14/2016
Printed 12/15/2016
CED Permit #:########
Existing Future Public Private
Right-of-Way Improvements Improvements
(D) (E)
Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost
SITE IMPROVEMENT BOND QUANTITY WORKSHEET
FOR STREET AND SITE IMPROVEMENTS
Quantity Remaining
(Bond Reduction)
(B)(C)
PARKING LOT SURFACING No.
2" AC, 2" top course rock & 4" borrow PL-1 21.00$ SY
2" AC, 1.5" top course & 2.5" base course PL-2 28.00$ SY
4" select borrow PL-3 5.00$ SY
1.5" top course rock & 2.5" base course PL-4 14.00$ SY
SUBTOTAL PARKING LOT SURFACING:
(B)(C)(D)(E)
LANDSCAPING & VEGETATION No.
Street Trees LA-1
Median Landscaping LA-2
Right-of-Way Landscaping LA-3
Wetland Landscaping LA-4
SUBTOTAL LANDSCAPING & VEGETATION:
(B)(C)(D)(E)
TRAFFIC & LIGHTING No.
Signs TR-1
Street Light System ( # of Poles)TR-2 6,000.00$ Each 3 18,000.00 5 30,000.00
Traffic Signal TR-3
Traffic Signal Modification TR-4
SUBTOTAL TRAFFIC & LIGHTING:18,000.00 30,000.00
(B)(C)(D)(E)
WRITE-IN-ITEMS
SUBTOTAL WRITE-IN ITEMS:
STREET AND SITE IMPROVEMENTS SUBTOTAL:41,249.75 102,971.00 73,818.00
SALES TAX @ 9.5%3,918.73 9,782.25 7,012.71
STREET AND SITE IMPROVEMENTS TOTAL:45,168.48 112,753.25 80,830.71
(B)(C)(D)(E)
Page 3 of 3
Ref 8-H Bond Quantity Worksheet SECTION II.b TRANSPORTATION
Unit Prices Updated: 06/14/2016
Version: 06/14/2016
Printed 12/15/2016
CED Permit #:########
Existing Future Public Private
Right-of-Way Improvements Improvements
(D) (E)
Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost
DRAINAGE (CPE = Corrugated Polyethylene Pipe, N12 or Equivalent) For Culvert prices, Average of 4' cover was assumed. Assume perforated PVC is same price as solid pipe.)
Access Road, R/D D-1 26.00$ SY 22 572.00 10 260.00
* (CBs include frame and lid)
Beehive D-2 90.00$ Each
Through-curb Inlet Framework D-3 400.00$ Each 2 800.00
CB Type I D-4 1,500.00$ Each 7 10,500.00 1 1,500.00
CB Type IL D-5 1,750.00$ Each
CB Type II, 48" diameter D-6 2,300.00$ Each 2 4,600.00
for additional depth over 4' D-7 480.00$ FT 18 8,640.00
CB Type II, 54" diameter D-8 2,500.00$ Each
for additional depth over 4'D-9 495.00$ FT
CB Type II, 60" diameter D-10 2,800.00$ Each
for additional depth over 4'D-11 600.00$ FT
CB Type II, 72" diameter D-12 6,000.00$ Each
for additional depth over 4'D-13 850.00$ FT
CB Type II, 96" diameter D-14 14,000.00$ Each
for additional depth over 4'D-15 925.00$ FT
Trash Rack, 12"D-16 350.00$ Each
Trash Rack, 15"D-17 410.00$ Each
Trash Rack, 18"D-18 480.00$ Each
Trash Rack, 21"D-19 550.00$ Each
Cleanout, PVC, 4"D-20 150.00$ Each
Cleanout, PVC, 6"D-21 170.00$ Each 8 1,360.00
Cleanout, PVC, 8"D-22 200.00$ Each
Culvert, PVC, 4" (Not allowed in ROW)D-23 10.00$ LF
Culvert, PVC, 6" (Not allowed in ROW)D-24 13.00$ LF 300 3,900.00
Culvert, PVC, 8" (Not allowed in ROW)D-25 15.00$ LF
Culvert, PVC, 12" (Not allowed in ROW)D-26 23.00$ LF
Culvert, PVC, 15" (Not allowed in ROW)D-27 35.00$ LF
Culvert, PVC, 18" (Not allowed in ROW)D-28 41.00$ LF
Culvert, PVC, 24" (Not allowed in ROW)D-29 56.00$ LF
Culvert, PVC, 30" (Not allowed in ROW)D-30 78.00$ LF
Culvert, PVC, 36" (Not allowed in ROW)D-31 130.00$ LF
Culvert, CMP, 8"D-32 19.00$ LF
Culvert, CMP, 12"D-33 29.00$ LF
SUBTOTAL THIS PAGE:24,312.00 2,300.00 5,520.00
(B)(C)(D)(E)
Quantity Remaining
(Bond Reduction)
(B)(C)
SITE IMPROVEMENT BOND QUANTITY WORKSHEET
FOR DRAINAGE AND STORMWATER FACILITIES
Page 1 of 5
Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE
Unit Prices Updated: 06/14/2016
Version: 06/14/2016
Printed 12/15/2016
CED Permit #:########
Existing Future Public Private
Right-of-Way Improvements Improvements
(D) (E)
Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost
Quantity Remaining
(Bond Reduction)
(B)(C)
SITE IMPROVEMENT BOND QUANTITY WORKSHEET
FOR DRAINAGE AND STORMWATER FACILITIES
DRAINAGE (Continued)
Culvert, CMP, 15"D-34 35.00$ LF
Culvert, CMP, 18"D-35 41.00$ LF
Culvert, CMP, 24"D-36 56.00$ LF
Culvert, CMP, 30"D-37 78.00$ LF
Culvert, CMP, 36"D-38 130.00$ LF
Culvert, CMP, 48"D-39 190.00$ LF
Culvert, CMP, 60"D-40 270.00$ LF
Culvert, CMP, 72"D-41 350.00$ LF
Culvert, Concrete, 8"D-42 42.00$ LF
Culvert, Concrete, 12"D-43 48.00$ LF
Culvert, Concrete, 15"D-44 78.00$ LF
Culvert, Concrete, 18"D-45 48.00$ LF
Culvert, Concrete, 24"D-46 78.00$ LF
Culvert, Concrete, 30"D-47 125.00$ LF
Culvert, Concrete, 36"D-48 150.00$ LF
Culvert, Concrete, 42"D-49 175.00$ LF
Culvert, Concrete, 48"D-50 205.00$ LF
Culvert, CPE, 6" (Not allowed in ROW)D-51 14.00$ LF
Culvert, CPE, 8" (Not allowed in ROW)D-52 16.00$ LF
Culvert, CPE, 12" (Not allowed in ROW)D-53 24.00$ LF
Culvert, CPE, 15" (Not allowed in ROW)D-54 35.00$ LF
Culvert, CPE, 18" (Not allowed in ROW)D-55 41.00$ LF
Culvert, CPE, 24" (Not allowed in ROW)D-56 56.00$ LF
Culvert, CPE, 30" (Not allowed in ROW)D-57 78.00$ LF
Culvert, CPE, 36" (Not allowed in ROW)D-58 130.00$ LF
Culvert, LCPE, 6"D-59 60.00$ LF
Culvert, LCPE, 8"D-60 72.00$ LF
Culvert, LCPE, 12"D-61 84.00$ LF 639 53,676.00 156 13,104.00
Culvert, LCPE, 15"D-62 96.00$ LF
Culvert, LCPE, 18"D-63 108.00$ LF
Culvert, LCPE, 24"D-64 120.00$ LF
Culvert, LCPE, 30"D-65 132.00$ LF
Culvert, LCPE, 36"D-66 144.00$ LF
Culvert, LCPE, 48"D-67 156.00$ LF
Culvert, LCPE, 54"D-68 168.00$ LF
SUBTOTAL THIS PAGE:53,676.00 13,104.00
(B)(C)(D)(E)
Page 2 of 5
Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE
Unit Prices Updated: 06/14/2016
Version: 06/14/2016
Printed 12/15/2016
CED Permit #:########
Existing Future Public Private
Right-of-Way Improvements Improvements
(D) (E)
Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost
Quantity Remaining
(Bond Reduction)
(B)(C)
SITE IMPROVEMENT BOND QUANTITY WORKSHEET
FOR DRAINAGE AND STORMWATER FACILITIES
DRAINAGE (Continued)
Culvert, LCPE, 60"D-69 180.00$ LF
Culvert, LCPE, 72"D-70 192.00$ LF
Culvert, HDPE, 6"D-71 42.00$ LF
Culvert, HDPE, 8"D-72 42.00$ LF
Culvert, HDPE, 12"D-73 74.00$ LF
Culvert, HDPE, 15"D-74 106.00$ LF
Culvert, HDPE, 18"D-75 138.00$ LF
Culvert, HDPE, 24"D-76 221.00$ LF
Culvert, HDPE, 30"D-77 276.00$ LF
Culvert, HDPE, 36"D-78 331.00$ LF
Culvert, HDPE, 48"D-79 386.00$ LF
Culvert, HDPE, 54"D-80 441.00$ LF
Culvert, HDPE, 60"D-81 496.00$ LF
Culvert, HDPE, 72"D-82 551.00$ LF
Pipe, Polypropylene, 6"D-83 84.00$ LF
Pipe, Polypropylene, 8"D-84 89.00$ LF
Pipe, Polypropylene, 12"D-85 95.00$ LF
Pipe, Polypropylene, 15"D-86 100.00$ LF
Pipe, Polypropylene, 18"D-87 106.00$ LF
Pipe, Polypropylene, 24"D-88 111.00$ LF
Pipe, Polypropylene, 30"D-89 119.00$ LF
Pipe, Polypropylene, 36"D-90 154.00$ LF
Pipe, Polypropylene, 48"D-91 226.00$ LF
Pipe, Polypropylene, 54"D-92 332.00$ LF
Pipe, Polypropylene, 60"D-93 439.00$ LF
Pipe, Polypropylene, 72"D-94 545.00$ LF
Culvert, DI, 6"D-95 61.00$ LF
Culvert, DI, 8"D-96 84.00$ LF
Culvert, DI, 12"D-97 106.00$ LF
Culvert, DI, 15"D-98 129.00$ LF
Culvert, DI, 18"D-99 152.00$ LF
Culvert, DI, 24"D-100 175.00$ LF
Culvert, DI, 30"D-101 198.00$ LF
Culvert, DI, 36"D-102 220.00$ LF
Culvert, DI, 48"D-103 243.00$ LF
Culvert, DI, 54"D-104 266.00$ LF
Culvert, DI, 60"D-105 289.00$ LF
Culvert, DI, 72"D-106 311.00$ LF
SUBTOTAL THIS PAGE:
(B)(C)(D)(E)
Page 3 of 5
Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE
Unit Prices Updated: 06/14/2016
Version: 06/14/2016
Printed 12/15/2016
CED Permit #:########
Existing Future Public Private
Right-of-Way Improvements Improvements
(D) (E)
Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost
Quantity Remaining
(Bond Reduction)
(B)(C)
SITE IMPROVEMENT BOND QUANTITY WORKSHEET
FOR DRAINAGE AND STORMWATER FACILITIES
Specialty Drainage Items
Ditching SD-1 9.50$ CY
Flow Dispersal Trench (1,436 base+)SD-3 28.00$ LF
French Drain (3' depth)SD-4 26.00$ LF
Geotextile, laid in trench, polypropylene SD-5 3.00$ SY
Mid-tank Access Riser, 48" dia, 6' deep SD-6 2,000.00$ Each
Pond Overflow Spillway SD-7 16.00$ SY
Restrictor/Oil Separator, 12"SD-8 1,150.00$ Each
Restrictor/Oil Separator, 15"SD-9 1,350.00$ Each
Restrictor/Oil Separator, 18"SD-10 1,700.00$ Each
Riprap, placed SD-11 42.00$ CY
Tank End Reducer (36" diameter)SD-12 1,200.00$ Each
Infiltration pond testing SD-13 125.00$ HR
Permeable Pavement SD-14
Permeable Concrete Sidewalk SD-15
Culvert, Box __ ft x __ ft SD-16
SUBTOTAL SPECIALTY DRAINAGE ITEMS:
(B)(C)(D)(E)
STORMWATER FACILITIES (Include Flow Control and Water Quality Facility Summary Sheet and Sketch)
Detention Pond SF-1 Each
Detention Tank SF-2 Each
Detention Vault SF-3 Each
Infiltration Pond SF-4 Each
Infiltration Tank SF-5 Each
Infiltration Vault SF-6 Each
Infiltration Trenches SF-7 Each
Basic Biofiltration Swale SF-8 Each
Wet Biofiltration Swale SF-9 Each
Wetpond SF-10 Each
Wetvault SF-11 160,500.00$ Each 1 160,500.00
Sand Filter SF-12 Each
Sand Filter Vault SF-13 Each
Linear Sand Filter SF-14 Each
StormFilter SF-15 Each
Rain Garden SF-16 Each
SUBTOTAL STORMWATER FACILITIES:160,500.00
(B)(C)(D)(E)
Page 4 of 5
Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE
Unit Prices Updated: 06/14/2016
Version: 06/14/2016
Printed 12/15/2016
CED Permit #:########
Existing Future Public Private
Right-of-Way Improvements Improvements
(D) (E)
Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost
Quantity Remaining
(Bond Reduction)
(B)(C)
SITE IMPROVEMENT BOND QUANTITY WORKSHEET
FOR DRAINAGE AND STORMWATER FACILITIES
WRITE-IN-ITEMS
WI-1
WI-2
WI-3
WI-4
WI-5
WI-6
WI-7
WI-8
WI-9
WI-10
WI-11
WI-12
WI-13
WI-14
WI-15
SUBTOTAL WRITE-IN ITEMS:
DRAINAGE AND STORMWATER FACILITIES SUBTOTAL:77,988.00 15,404.00 166,020.00
SALES TAX @ 9.5%7,408.86 1,463.38 15,771.90
DRAINAGE AND STORMWATER FACILITIES TOTAL:85,396.86 16,867.38 181,791.90
(B)(C)(D)(E)
Page 5 of 5
Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE
Unit Prices Updated: 06/14/2016
Version: 06/14/2016
Printed 12/15/2016
Planning Division |1055 South Grady Way – 6th Floor | Renton, WA 98057 (425) 430-7200
Date:
Name:Project Name:
PE Registration No:CED Plan # (LUA):
Firm Name:CED Permit # (U):
Firm Address:Site Address:
Phone No.Parcel #(s):
Email Address:Project Phase:
Site Restoration/Erosion Sediment Control Subtotal (a)(a)105,590.85$
Existing Right-of-Way Improvements Subtotal (b)(b)45,168.48$
Future Public Improvements Subtotal (c)(c)112,753.25$
Stormwater & Drainage Facilities Subtotal (d)(d)284,056.14$
Bond Reduction (Quantity Remaining)2 (e)(e)-$
Site Restoration
Civil Construction Permit
Maintenance Bond 88,395.57$
Bond Reduction2
Construction Permit Bond Amount 3
Minimum Bond Amount is $10,000.00
1 Estimate Only - May involve multiple and variable components, which will be established on an individual basis by Development Engineering.
2 The City of Renton allows one request only for bond reduction prior to the maintenance period. Reduction of not more than 70% of the original bond amount, provided that the remaining 30% will
cover all remaining items to be constructed.
3 Required Bond Amounts are subject to review and modification by Development Engineering.
* Note: The word BOND as used in this document means any financial guarantee acceptable to the City of Renton.
** Note: All prices include labor, equipment, materials, overhead and profit.
R
((b)+(c)+(d)) x 150%
EST1
((b) + (c) + (d)) x 20%
-$
MAINTENANCE BOND */**
(after final acceptance of construction)
105,590.85$
45,168.48$
662,966.79$
158,386.28$
-$
112,753.25$
284,056.14$
S
(e) x 150%
SITE IMPROVEMENT BOND QUANTITY WORKSHEET
BOND CALCULATIONS
12/14/2016
Jonathan S. Murray, P.E.
50096
D.R. STRONG Consulting Engineers, Inc.
T
(P +R - S)
Prepared by:Project Information
CONSTRUCTION BOND AMOUNT */**
(prior to permit issuance)
(425) 827-3063
jonathan.murray@drstrong.com
Bethany Corner
##-######
16433 & 16451 111th Ave SE
008800-0560, -0570
FOR APPROVAL
########
620 7th Avenue, Kirkland, WA 98033
821,353.07$
P
(a) x 150%
Page 1 of 1
Ref 8-H Bond Quantity Worksheet SECTION III. BOND WORKSHEET
Unit Prices Updated: 06/14/2016
Version: 06/14/2016
Printed 12/15/2016