HomeMy WebLinkAboutRS_44th_Street_Staging_Area_TIR_TESC Stamped_210329_v2
PRELIMINARY
TECHNICAL INFORMATION REPORT
City of Renton
Project Area: NE 44th Street Field Offices and
Laydown/Staging Area
Project: I-405 Renton to Bellevue Widening and ETL
Project, I-5 (MP 0.0)
to NE 6th Street (MP 14.6)
WSDOT Contract No. XL5467
KING COUNTY, WASHINGTON
Northwest Region
I-405 Program
Bellevue, Washington
Tyler ZoBell, P.E.
Flatiron Lane, A Joint Venture
1400 Talbot Road South, #500
Renton, Washington 98055
January 2021
March 2021
DEVELOPMENT ENGINEERING
Nathan Janders 04/12/2021
ii
Table of Contents
List of Tables ...................................................................................................................iv
List of Figures .................................................................................................................. v
Section 1 - Project Overview ........................................................................................... 1
1.1 General Description ...................................................................................... 1
Section 2 - Conditions and Requirements Summary ..................................................... 12
2.1 Analysis of the 9 Core Requirements ......................................................... 15
2.1.1 Core Requirement #1: Discharge at the Natural Location ........................ 15
2.1.2 Core Requirement #2: Off-site Analysis.................................................... 15
2.1.3 Core Requirement #3: Flow Control Facilities .......................................... 16
2.1.4 Core Requirement #4: Conveyance System ............................................. 16
2.1.5 Core Requirement #5: Erosion and Sediment Control .............................. 16
2.1.6 Core Requirement #6: Maintenance and Operations ............................... 17
2.1.7 Core Requirement #7: Financial Guarantees and Liability........................ 17
2.1.8 Core Requirement #8: Water Quality Facilities ......................................... 18
2.1.9 Core Requirement #9: On-site Best Management Practices (BMPs) ....... 18
2.2 Analysis of the 6 Special Requirements ..................................................... 18
2.2.1 Special Requirement #1: Other Adopted Area-Specific Requirements ..... 18
2.2.2 Special Requirement #2: Flood Hazard Area Determination .................... 19
2.2.3 Special Requirement #3: Flood Protection Facilities ................................ 19
2.2.4 Special Requirement #4: Source Control.................................................. 19
2.2.5 Special Requirement #5: Oil Control ........................................................ 19
2.2.6 Special Requirement #6: Aquifer Protection Areas ................................... 20
2.3 Adjustments to Core or Special Requirements ........................................... 21
Section 3 - Off-Site Analysis .......................................................................................... 23
Section 4 - Flow Control, Low Impact Development (LID), and Water Quality Facility
Analysis and Design. .................................................................................. 24
Section 5- Conveyance System Analysis and Design ................................................... 26
Section 6 - Special Reports and Studies ....................................................................... 28
Section 7 - Other Permits (Special Use, WSDOT, DOE Permit with WAR #, etc.) ........ 30
Section 8 - CSWPPP Analysis and Design ................................................................... 32
8.1 Introduction to CSWPPP ............................................................................ 34
8.1.1 Site Operations and Potential Pollutants ................................................... 34
iii
8.2. Erosion and Sediment Control (ESC) Plan ................................................. 35
8.2.1 ESC Measures .......................................................................................... 35
8.3 Stormwater Pollution Prevention and Spill Control (SWPPS) Plan ............. 40
8.3.1 SWPPS Measures ..................................................................................... 40
8.4 CSWPP Performance and Compliance Provisions ..................................... 44
8.4.1 CSWPP Supervisor ................................................................................... 44
8.4.2 Monitoring of Discharges ........................................................................... 45
8.4.3 ESC Performance ...................................................................................... 45
8.4.4 SWPPS Performance ................................................................................ 46
8.4.5 Flexible Compliance .................................................................................. 46
8.4.6 Roads and Utilities Compliance ................................................................. 46
8.4.7 Alternative Measures ................................................................................. 46
8.5 CSWPP Implementation Requirements ...................................................... 47
8.5.1 CSWPP Plan ............................................................................................. 47
8.5.2 Wet Season Requirements ........................................................................ 47
8.5.3 Critical Areas Restrictions .......................................................................... 47
8.5.4 Maintenance Requirements ....................................................................... 48
8.5.5 Final Stabilization ...................................................................................... 48
8.5.6 NPDES Requirements ............................................................................... 49
8.5.7 Forest Practice Permit Requirements ........................................................ 49
Section 9 - Bond Quantities, Facility Summaries, and Declaration of Covenant ........... 50
Section 10 - Operations and Maintenance Manual ....................................................... 55
10.1 Implementation, Installation, Inspection, and Maintenance Forms ............. 57
10.2 Installation Specifications and Maintenance Requirements – ESC Plan
BMPs ................................................................................................................... 68
References ................................................................................................................... 84
iv
List of Tables
Table 1 I-405 44th Street Field Offices and Laydown Area
General Summary of Stored Materials and Potential Pollutants…….…35
Table 2 I-405 44th Street Field Offices and Laydown Area
Summary of Storage Areas and BMPs……………………………………41
v
List of Figures
Figure 1 TIR Worksheet……………………………………………………….…..……2
Figure 2 Site Location Map…………………………………………………..….….….8
Figure 3 Site Characteristics………………………………………………….…..……9
Figure 4 Site Soil Information…………………………………………………………10
Figure 5 Drainage Review Type Flowchart…………………………….……….......13
Figure 6 Drainage Review Requirements…………………………………..….……14
Figure 7 City of Renton, Aquifer Protection Area…………………………….……. 21
Figure 8 Existing Facility Map…………………………………………………….…. 37
Figure 9 ESC Plan.......….................................................................................... 38
Figure 10 SWPPS Plan………………………………………………………………... 42
Figure 11 Bond Quantity Spreadsheet………………………………………….……. 51
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Section 1 - Project Overview
1.1 General Description
Overall Project: I-405 Renton to Bellevue Widening and ETL
Project from I-5 (MP 0.0) to NE 6th Street (MP
14.6).
Site: NE 44th Street Field Offices and
Laydown/Staging Areas.
Street/Location: 4350 Lake Washington Boulevard North
Renton, Washington 98055
Receiving Waterbody: Lake Washington
The Renton to Bellevue Widening and Express Toll Lanes (ETL) Project (the overall I-
405 improvement project) proposes to add one lane to I-405 in each direction for
approximately eight miles beginning on I-405 near SR167, continuing to approximately
1 mile north of I-90. The Project is entirely within King County and includes work within
unincorporated King County, the City of Renton (CoR), and the City of Bellevue. There
is also minor widening for safety improvements along the southbound I-405 mainline in
the City of Tukwila and within the northbound off-ramp to SR 520 in the City of Bellevue.
In addition to widening I-405, the Project includes trail work along the Eastside Rail
Corridor from Ripley Lane in Renton to the Wilburton area in Bellevue. To facilitate plan
development, the design has been broken into five segments: 1A, 1B, 2A, 2B, and 2C.
This Technical Information Report (TIR) will only focus on a parcel of land within
Segment 1B of the project in the southwest portion of the intersection of NE 44th Street
and I-405. The site is currently owned by Vulcan, Inc. and is used for material storage,
although there is little to no activity at this facility. The site is proposed for use by the
Flatiron/Lane joint venture as a field office for up to 148 employees during the
construction of the I-405 project. The site will also be used as a laydown/staging area
for construction materials, equipment, and vehicles. The project is required to comply
with the Nine Core Requirements and Six Special Requirements for a full drainage
review as stated in the CoR Surface Water Design Manual (SWDM). The required TIR
Worksheet for the site is shown below in Figure 1. A Site Location Map is shown in
Figure 2. Figure 3 shows the existing site characteristics. Figure 4 shows the existing
soil information for the site.
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Figure 1 – TIR Worksheet
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Figure 1 (Continued) – TIR Worksheet
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Figure 1 (Continued) – TIR Worksheet
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Figure 1 (Continued) – TIR Worksheet
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Figure 1 (Continued) – TIR Worksheet
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Figure 2 – Site Location Map
May
NE 44th Street – Office,
Staging/Laydown Area
Existing Catch
Basins at Facility
Entrance
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Figure 3 – Site Characteristics
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Figure 4 – Site Soil Information
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Figure 4 (Continued) – Site Soil Information
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Section 2 - Conditions and Requirements
Summary
As discussed in Section 1, the project is required to comply with Core Requirements 1-9
and Special Requirements 1-6 as required by the CoR SWDM. Figures 5 and 6 below
are excerpts from the SWDM that are used to determine the type of drainage review
that will be required for the project and to identify which requirements are applied for
each type of drainage review.
The flowchart in Figure 5 shows that the NE 44th Street Office/Staging site is subject to
a “Targeted” Drainage Review. The site is not a single family residential project and the
impervious surfaces at the site will not change from existing conditions. The site is
adjacent to the 100-year Special Flood Hazard Area (100-year floodplain) for May
Creek. Figure 2 shows that a small portion of the southern limit of the site is located
within the May Creek floodplain. As a result, this site falls within the guidelines of a
Targeted Drainage Review.
The tables in Figure 6 show that the site is under the guidelines of Core Requirement
#5. Core Requirements #1-4 and #6-8 are subject to review by the CoR Community
and Economic Development Department (CED) and will depend on project or site-
specific conditions. The table also shows that Special Requirements #1-4 and #6 are
applicable to the site. The requirements may have exemptions or thresholds that may
preclude or limit their application to the 44th Street site.
The remainder of this section summarizes each of the nine Core Requirements and the
six Special Requirements and the site conditions, site drainage, activities, operations,
and Best Management Practices (BMPs) that apply to each core and special
requirement.
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Figure 5 – Drainage Review Type Flowchart
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Figure 6 – Drainage Review Requirements
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Figure 6 (Continued) – Drainage Review Requirements
2.1 Analysis of the 9 Core Requirements
2.1.1 Core Requirement #1: Discharge at the Natural Location
Site Condition: There are no areas at the site where stormwater drains directly into a
natural channel, except for a very small area along the southern boundary where
stormwater drains directly into May Creek. There are no proposed changes to site
grading or to the current pervious/impervious cover so existing drainage conditions will
not change. All other on-site drainage is collected in several existing catch basins
throughout the property and is conveyed in the existing storm drain system. This storm
drainage system is shown in Figure 2 in the previous section.
2.1.2 Core Requirement #2: Off-site Analysis
Site Condition: All stormwater runoff at the NE 44th Street site is generated on-site,
with the exception of flow that drains off of the west embankment of the southbound I-
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405 on ramp. The stormwater from the embankment is conveyed by sheet flow to the
on-site inlets throughout the facility. Off-site flow that approaches the north entrance
from the Seahawks Way/44th Street Intersection is captured by two existing catch
basins in the entrance road that approaches the north boundary gate. These catch
basins are shown in Figure 2. Stormwater from Lake Washington Boulevard along the
west side of the site is captured in a roadside ditch. This ditch drains stormwater along
the west perimeter boundary and does not drain into the site. There are no changes
proposed to on-site or off-site flow patterns and no changes are proposed to the existing
ground cover at the facility. As a result, an off-site drainage analysis was not
considered.
2.1.3 Core Requirement #3: Flow Control Facilities
Site Condition: The SWDM states that proposed projects, including redevelopment
projects, must provide on-site flow control facilities to mitigate the impacts of storm and
surface water runoff generated by new impervious surfaces, new pervious surfaces, and
replaced impervious surfaces. The intent is to protect downstream properties from
increases in peak, duration, and volume of runoff generated by new development. The
project can be exempt from the core requirement if less than 5,000 square feet of new
plus replaced impervious surface will be created and less than ¾ of an acre of new
pervious surface will be added. The ground cover at the site will not be modified from
the existing condition. Therefore, the site is exempt from Core Requirement #3.
2.1.4 Core Requirement #4: Conveyance System
Site Condition: For this requirement, the SWDM outlines the procedures for the
analysis, design, and construction of new conveyance systems to provide a minimum
level of protection against overtopping, flooding, erosion, and structural failure. The
SWDM also states that existing conveyance systems do not need to be analyzed if the
project will not change the flow characteristics (peak runoff or volume) at the site. There
are no proposed changes to site grading, pervious/impervious surfaces, off-site flow
patterns, or to the existing on-site conveyance systems (catch basins, pipes, manholes)
shown in Figure 2. As a result, an analysis of the existing conveyance system is not
required.
2.1.5 Core Requirement #5: Erosion and Sediment Control
Site Condition: As discussed in earlier sections of this report, there are no plans to
modify the grading, land cover, or the existing stormwater conveyance system
throughout the site. The proposed activity will be the only change at this facility,
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including the use of temporary buildings for office space and areas where construction
materials, vehicles, and equipment will be stored and stockpiled. The SWDM discusses
the requirements for construction stormwater pollution prevention (erosion and sediment
controls) for projects that will clear, grade, or otherwise disturb the proposed site.
These controls are used to prevent, reduce, or eliminate the discharge of sediments
and/or pollutants to stormwater systems and watercourses. Erosion and Sediment
Control (ESC) measures and Stormwater Pollution Prevention and Spill Control
(SWPPS) measures must be applied through a comprehensive Construction
Stormwater Pollution Prevention (CSWPP) plan.
Although there are no planned modifications to the topography, cover, or storm drains at
the site, the increase in activity (offices, stored materials and equipment, etc.) will
require the use of on-site BMPs throughout the duration of the I-405 project to prevent
or minimize the discharge of potential pollutants into the existing storm drainage system
and May Creek. A full CSWPP plan for this facility is found in Section 8 of this report.
2.1.6 Core Requirement #6: Maintenance and Operations
Site Condition: The existing storm drainage system throughout the facility is shown in
the CSWPP plan in Section 8. The CoR GIS data in Figure 2 shows the perimeter
storm drainage systems around the site. This system is maintained by WSDOT. A
storm drainage trunkline is also shown along the west side of the facility that collects
stormwater from Lake Washington Boulevard. This line is maintained by the CoR. The
SWDM requires that the maintenance and operation of all private drainage facilities will
be performed by the applicant or property owner, except for areas where the City has
agreed to assume maintenance/operational responsibilities. Since the on-site drainage
system is not shown in the GIS data, it is assumed that the maintenance and operation
of the site will be the responsibility of the Flatiron/Lane Joint Venture.
2.1.7 Core Requirement #7: Financial Guarantees and Liability
Site Condition: The SWDM states that the CoR CED will require anyone constructing
surface water facilities (including flow control, water quality facilities, conveyance
systems, erosion control, and road drainage) to post a bond, assignment of funds, or a
certified check with the CoR. This requirement is intended to ensure financial
guarantees will sufficiently cover the cost of correcting, if necessary, incomplete or
substandard construction work and to warrant the performance and maintenance of
newly constructed facilities. It is also intended to provide a liability policy that protects
the proponent and the City from damages. This site will only utilize erosion control
BMPs and no other surface water facilities will be constructed on-site. A bond
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quantities spreadsheet for erosion control BMPs, provided on the CoR website, is
included in Section 9 of this report.
2.1.8 Core Requirement #8: Water Quality Facilities
Site Condition: The SWDM requires that all proposed projects, including
redevelopment, must provide water quality facilities to treat the runoff from all new and
replaced pollution generating impervious surfaces (PGIS) and new pollution generating
pervious surfaces (PGPS). However, the site is exempt from this requirement if there is
less than 5,000 square feet of new plus replaced PGIS and less than ¾ acre of new
PGPS that is not fully dispersed. Since no changes are being made to the existing
pervious/impervious surfaces, this facility is exempt from Core Requirement #8.
2.1.9 Core Requirement #9: On-site Best Management Practices (BMPs)
Site Condition: On-site BMPs must be provided to mitigate the impacts of storm and
surface water runoff generated by new impervious and pervious surfaces, existing
impervious surfaces, and replaced impervious surfaces. The site is exempt from this
requirement if there is less than 2,000 square feet of new plus replaced impervious
surface created and less than 7,000 square feet of land disturbing activities will occur.
As discussed for Core Requirement #5, the existing pervious/impervious land cover at
the site will not be modified, and the site is exempt from this requirement based on the
criteria listed. However, even though the site is exempt from this core requirement,
BMPs will be established on-site due to the increase in activity at the site from office
and staging/storage operations. A full CSWPP plan for this facility is found in Section 8
of this report.
2.2 Analysis of the 6 Special Requirements
2.2.1 Special Requirement #1: Other Adopted Area-Specific Requirements
Site Condition: The SWDM discusses other adopted regulations that have
requirements for controlling drainage. Other regulations include Master Drainage Plans,
Basin Plans, Lake Management Plans, Hazard Mitigation Plans, and Shared Facility
Drainage Plans. No other regulations or plans that included this facility were found on
the CoR website.
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2.2.2 Special Requirement #2: Flood Hazard Area Determination
Site Condition: Flood hazard areas are composed of the 100-year floodplain and
floodway as determined by the Federal Emergency Management Agency (FEMA). If a
proposed project contains or is adjacent to a flood hazard area, this special requirement
states that the flood hazard area be delineated on the project site maps. As stated
earlier in this report, a small portion of the May Creek 100-year floodplain runs along the
south boundary of the site. The floodplain boundary is shown in the Site Location Map
in Figure 2 and the Site Characteristics Map in Figure 3. The floodplain is also shown in
the CWSPP figures.
2.2.3 Special Requirement #3: Flood Protection Facilities
Site Condition: The SWDM describes flood protection facilities as levees and
revetments that protect against possible catastrophic flooding if these structures were to
fail. The NE 44th Street facility does not have any existing flood protection facilities and
none will be built at the site.
2.2.4 Special Requirement #4: Source Control
Site Condition: Source controls are described in the SWDM as measures to prevent
rainfall and runoff from coming into contact with pollutants and reducing the likelihood
that pollutants will enter public waterways and violate water quality standards or permit
requirements. As discussed earlier in this report, the NE 44th Street site will be used to
accommodate office facilities and will also contain laydown/staging/storage areas. The
operations at the site will require the use of source control BMPs throughout the
duration of the I-405 project to prevent or minimize the potential discharge of pollutants
into neighboring waterways. All source control BMPs are described in the CSWPP plan
for this facility. This plan is found in Section 8 of this report.
2.2.5 Special Requirement #5: Oil Control
Site Condition: The SWDR states that for projects proposing to develop or redevelop
a “high-use site”, oil controls must be provided in addition to any other water quality
controls that are required. High-use is described as any sites that have high
concentrations of oil due to high traffic turnover, on-site vehicle or heavy /stationary
equipment use, automotive recycling, or operations that require frequent transfer of
petroleum products. The NE 44th Street site will have automobile traffic from employees
using the on-site office space as well as construction vehicle and equipment traffic.
BMPs for on-site oil control treatment will be used, if necessary, in compliance with the
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requirements of the CoR. All BMPs in use at the site are found in the CSWPP plan
found in Section 8 of this report.
2.2.6 Special Requirement #6: Aquifer Protection Areas
Site Condition: Based on GIS data from the CoR, this site is not located in an aquifer
protection area as shown in Figure 7.
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Figure 7 – City of Renton, Aquifer Protection Area
2.3 Adjustments to Core or Special Requirements
Site Condition: The SWDM describes the process required for projects where a
variance from any of the core or special requirements, or any other specific criteria from
NE 44th Street Site
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the manual is requested. As discussed earlier in this report, there will be no changes to
the grading, land cover, or the drainage system at the site. As a result, no variances to
the requirements or criteria will be requested.
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Section 3 - Off-Site Analysis
As discussed in Section 2 of this report, the grading, land cover, and drainage system of
this facility will not be modified. Precipitation falling on the southbound on-ramp from
44th Street to I-405 will drain to an existing storm conveyance system located along the
west side of the on-ramp. Flow on the embankment slope along the west side of the
on-ramp will be conveyed by sheet flow to the existing storm drainage inlets at the 44th
Street site. Another existing storm drain system is located along the west perimeter of
the site, and captures flow from the Lake Washington Boulevard pavement area. The
roadway storm drainage systems are shown in the CoR GIS data on Figure 2. The
figure also shows that any stormwater draining from NE 44th Street toward the north
entrance to the site will be intercepted by existing catch basins before it reaches the
facility.
This on-site system is shown in the CSWPP Plan in Section 8 of this report. The on-site
system is connected to the trunkline which runs along the west side of the facility.
Figure 2 shows that this trunkline discharges stormwater to May Creek, just southwest
of the site. Figure 2 also shows a small toe ditch in the southwest corner that collects
some minor sheet flows from the facility. This ditch is connected to the existing storm
drain system that discharges to May Creek. Since there will be no changes to existing
site grading and ground cover, and no changes to any existing drainage patterns or
infrastructure, no off-site analysis is required.
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Section 4 - Flow Control, Low Impact
Development (LID), and Water Quality
Facility Analysis and Design.
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The existing site is approximately 7.3 acres that is paved with asphalt. The site will be
used for temporary office space for engineering and construction employees as well as
the storage of construction materials. No flow controls, LID development, or water
quality facilities will be used at the site.
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Section 5- Conveyance System Analysis and
Design
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The existing site is approximately 7.3 acres that is paved with asphalt. An existing
stormwater conveyance system is located throughout the site. This system includes
catch basins, manholes, and storm drain piping. The on-site conveyance system ties
into the Lake Washington Boulevard system along the east side of the street, ultimately
draining into May Creek. No grading will be done at the site and there will be no
changes to the ground cover/impervious characteristics at the facility. As a result, there
will be no changes to existing drainage patterns or discharges to on-site conveyance
structures. The site will be used for temporary office space for engineering and
construction employees as well as the storage of construction materials. Since existing
drainage patterns, volumes, and discharges are not affected, no conveyance analysis
was performed.
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Section 6 - Special Reports and Studies
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There are no known existing special reports or studies that included this area on the
west side of I-405.
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Section 7 - Other Permits (Special Use,
WSDOT, DOE Permit with WAR #, etc.)
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A Tier II Temporary Use Permit (TUP) and SEPA Environmental Review was obtained
on April 24, 2020 from the Department of Community and Economic Development
(CED). The TUP was to allow for the implementation of the temporary office buildings
and the laydown/staging area. Although other permits have been obtained for the
overall I-405 project, there are no additional permits for this site. The specific TUP file
numbers are shown below:
Project File Number: PR19-000486
Land Use File Number: LUA19-000318, ECF, TP
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Section 8 - CSWPPP Analysis and Design
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Construction Stormwater
Pollution Prevention Plan (CSWPPP)
-Erosion/Sediment Control Plan (ESC)
-Stormwater Pollution Prevention and Spill Control (SWPPS)
City of Renton
Project Area: NE 44th Street Field Offices and
Laydown – Staging/Storage Areas
Project: I-405 Renton to Bellevue Widening and ETL
Project, I-5 (MP 0.0)
to NE 6th Street (MP 14.6)
WSDOT Contract No. XL5467
KING COUNTY, WASHINGTON
Northwest Region
I-405 Program
Bellevue, Washington
Xxxxx xxxxxxx P.E.
Flatiron Lane, A Joint Venture
1400 Talbot Road South, #500
Renton, Washington 98055
January 2021 March 2021
Tyler ZoBell,
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8.1 Introduction to CSWPPP
Construction sites, including active construction and staging/storage areas, have the
potential to contaminate stormwater from the erosion of exposed soil areas, the
transport of sediments to local waterways, and by the ineffective management of on-site
activities, maintenance of storage and stockpile areas, and a lack of good housekeeping
practices. This CSWPPP consists of an Erosion and Sediment Control (ESC) Plan to
address the control of soil areas that are subject to erosion and the methods used to
minimize or eliminate the transport of sediments in stormwater. This CSWPPP also
consists of a Stormwater Pollution Prevention and Spill Control (SWPPS) Plan that
describes the activities, controls, procedures, and other practices used in day-to-day
operations on-site to reduce the potential for stormwater pollution.
8.1.1 Site Operations and Potential Pollutants
The site will be used as a dry materials storage and transfer yard. Two temporary office
structures will be constructed on site for use by design and construction personnel
throughout the duration of the project. A layout of the existing site is shown in Figure 8.
The storage and office areas are shown in Figure 10.
The materials that will be stored at the facility, including potential pollutants, are shown
in Table 1 below.
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Table 1 – I-405 44th Street Field Offices and Laydown Area
General Summary of Stored Materials and Potential Pollutants
Storage/Operation
Category
Materials Potential Pollutants
Utility/Electrical/Traffic Control Steel and Plastic Pipe
Concrete Structures
Pipe Lubricant/Cement
Aggregates
Traffic Control Items
Electrical Components
Dirt/dust that may be on
materials when they are
delivered. Concrete dust on
concrete structures.
Lubricants.
Erosion Control Silt Fence/Straw Waddles
Inlet Sleeves
Straw
Polyethylene Sheeting
Plastic Fencing (High
Visibility)
Minimal pollutants from these
types of materials.
Small Tool Storage (Conex
Boxes)
Electric/Gas Powered Hand
Tools
Rigging
Fasteners
Pumps/Hoses
Dirt/dust that may be on
materials when they are
delivered. Oil/gas/grease for
hand tools.
Large Equipment Staging* Dozers/Excavators
Loaders/Forklifts
Vacuum Trucks/Lowboy
Dirt on vehicles when they
enter the facility. Potential
leaks of oil/fuel/grease.
Operations Aggregates Staging (Import
and Export w/Truck and
Trailer)
Aggregates Site Delivery
(Import and Export w/Truck)
Dirt on materials when they
are delivered to the facility.
Materials themselves are also
potential pollutants.
*Note: No Fueling or Large Equipment Maintenance Will Be Performed at the Site
8.2. Erosion and Sediment Control (ESC) Plan
The purpose of the ESC is to describe the Best Management Practices (BMPs) that will
be used at the NE 44th Street site to prevent the erosion of exposed soil areas and the
potential transport of sediments to May Creek, either by overland flow or in the storm
drain conveyance system.
8.2.1 ESC Measures
1. Clearing Limits - There will be no clearing, grubbing, or grading at the site and
the existing ground cover will not change. The site is mostly paved with asphalt,
with some landscaped areas around the entrance to the facility. There are
several large trees along the south side of the site and some are within the
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44th Street Field Offices and Laydown/Storage Area Page 36
floodplain boundaries of May Creek. The trees and the floodplain constitute a
Shoreline Buffer Area and will be marked by High Visibility Fencing (HVF) as
shown the ESC Plan on Figure 9.
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44th Street Field Offices and Laydown/Storage Area Page 37
Figure 8 – Existing Facility Map
Dispersion ZoneWater Routed to Dispersion via PVC Plastic Cover Material (to be hydro-seeded)Covered Stockpile Silt FenceBaker Tank BermSubmersible PumpTrash DumpsterCB Plugged and ProtectedSpill KitHigh Visibility FencePlaced BermDrip Protection Fencing59.9 ftTruck EntranceTruck ExitDrafted by:Zachary T. Wallace FE / ECI 01/21/2021Edited by HenrikLabreche03/12/202144th Yard TESC PlanPipe Outlet (drain)Plugged offSump 2 Subm.PumpsOil/Sediment Booms/ Silt ProtectionCold Patch BermRumble PlatesRumble PlatesSewer ManholeDischarge LocationSump 2 Subm. Pumps toBaker Tank- Outlet PluggedREMOV
E
D
1
/
1
7
-
1
/
2
2 CB Sock Installedfor addedprotectionCB Sock Installedfor addedprotectionSilt FenceSediment Protection Setaround CB - Sand BagsSediment Protection Setaround CB - Sand BagsGravel borrow forembankment1 1/4" minus forbase course5/8" top courseGravel borrow forwall backfillCrushed rockTemporary officetrailers andbathroomsSilt Fence
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2. Cover Measures - There are no disturbed soil areas at the site. Temporary or
permanent cover measures will not be used.
3. Perimeter Protection - Perimeter protection will be provided at all on-site catch
basins, borrow/backfill stockpiles along the east side of the facility, and in the
area at the southwest portion of the site where runoff from a small area drains
into the drainage ditch/sump for the off-site Lake Washington Boulevard storm
drainage system. These BMPs will be maintained throughout the duration of the
I-405 construction. These BMPs are shown on the ESC Plan on Figure 9.
4. Traffic Area Stabilization – Site ingress and egress as well as site parking will be
entirely on asphalt paved surfaces. No traffic area stabilization will be used.
Rumble plates are used to clean trucks wheels only.
5. Sediment Retention – No sediment retention BMPs will be used at the site since
there are no disturbed areas.
6. Surface Water Collection – There are no areas on the site where surface water
will drain off of disturbed areas. All site water is collected within closed or
blocked catch basins and conveyed to baker tanks pre-treatment prior to
discharge to sewer. See permit SS20004735 along with discharge authorization
4548-01.
7. Dewatering Control – There are no dewatering activities at this site.
8. Dust Control – Since there are no disturbed areas, dust control BMPs will not be
used.
9. Flow Control – There are no changes to the ground cover at the site and there
will be no runoff from disturbed surfaces. Runoff from the site drains to several
catch basins as shown on the ESC Plan in Figure 9. Flow control measures will
not be needed.
10. Control Pollutants – On-site activities will include storage of construction
materials and equipment, vehicle storage, and employee parking. Temporary
buildings will be constructed on-site and will be used as office space for
employees working on the design and construction of the project. BMPs used for
control of pollutants from these activities will be discussed in the Stormwater
Pollution Prevention and Spill Control (SWPPS) Plan.
11. Protect Existing and Proposed Stormwater Facilities and On-site BMPs – There
are no existing stormwater facilities on the site, other than the existing catch
basins that drain to the Lake Washington Boulevard storm conveyance system.
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There are no existing stormwater BMPs at the site. BMPs will be established at
the site and will be protected/maintained as required throughout the duration of
the I-405 project. The BMPs are shown in the ESC Plan in Figure 9.
12. Maintain Protective BMPs – BMPs established at the site will be protected and
maintained as per the CoR CSWPP Requirements.
13. Manage the Project – BMPs at the site will be inspected, maintained, and
repaired or replaced as per the CoR CSWPP Requirements.
8.3 Stormwater Pollution Prevention and Spill Control
(SWPPS) Plan
8.3.1 SWPPS Measures
1. Concrete Handling – No concrete, grout, or other similar materials will be used or
stored at this site. Concrete handling BMP’s will not be required. Concrete pipe,
inlet boxes, and/or manhole components will be stored at the site. Concrete dust
is a potential pollutant that could be washed off these surfaces during a
precipitation event. However, the perimeter controls established in the ESC plan
will capture any concrete dust in stormwater and prevent these materials from
entering the existing stormwater conveyance system.
2. Concrete Washout and Disposal – Concrete washout will not be performed at
this site. Concrete washout and disposal BMPs will not be required.
3. Sawcutting and Surfacing Pollution Prevention – Sawcutting will not be done at
this site.
4. Material Delivery, Storage, and Containment – Table 1 in the previous section
summarizes the materials and equipment that will be delivered and stored at the
site. The table shows that the materials stored at the site will be dry materials.
No large quantities of liquids, petroleum products, chemicals, oil, grease, or other
such substances will be stored at the site. Very small amounts of oils and/or
grease used for hand or power tools may be stored at the site. The storage
areas around the site are shown in Figure 10. Table 2 below summarizes each
storage area and the materials that will be placed in the storage areas. Note that
loading and unloading operations will be observed to ensure compliance with the
requirements of the CSWPP Plan. This will include observation of front-end
loaders and dump trucks for fuel or oil leaks. A spill kit(s) will be kept at the
facility for use in the event of a spill during loading, unloading, or for use in
vehicle storage areas. All vehicles brought into the site, including larger
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construction vehicles, pickup trucks, and private vehicles should be routinely
inspected for leaks. Vehicles found to be leaking fluids will be immediately
removed from the site for repairs.
Table 2 – I-405 44th Street Field Offices and Laydown Area
Summary of Storage Areas and BMPs (Figure 10)
Storage Area Materials BMPs
Trash Containers Office trash, scrap wood, scrap metal Covered Dumpsters – No
precipitation contact.
Portable Restroom Restroom wastes Located in sump area. Spill kit
must be available during pumping.
Conex Containers Electric, gas powered, and manual
hand tools
Small amounts of oils/grease may
be stored. These are covered and
locked containers – No
precipitation contact.
Storage Area 1 Existing buildings. General material
storage.
Covered Building – No
precipitation contact.
Storage Area 2* CSBC road base Perimeter controls at on-site storm
drain inlets. Ecology blocks
around stockpile.
Storage Area 3* Retaining wall backfill Perimeter controls at on-site storm
drain inlets. Ecology blocks
around stockpile, open on west
side.
Storage Area 4* Structural backfill Perimeter controls at on-site storm
drain inlets. Ecology blocks
around stockpile, open on west
side.
Storage Area 5* Common borrow material Perimeter controls at on-site storm
drain inlets. Ecology blocks
around stockpile, open on west
side.
Storage Area 6* Drainage rock Perimeter controls at on-site storm
drain inlets. Ecology blocks
around stockpile, open on west
side.
Storage Area 7* Miscellaneous fill material Perimeter controls at on-site storm
drain inlets. Ecology blocks
around stockpile, open on west
side.
Storage Area 8* Export material Perimeter controls at on-site storm
drain inlets. Ecology blocks
around stockpile, open on west
side.
Storage Area 9 Temporary office No BMPs required.
Storage Area 10 Temporary office No BMPs required.
Storage Area 11
Storage Area 12
Storage Area 13
Concrete forms, concrete storm
structures, pipe, backhoe implements,
dry goods. Retaining wall
components, geogrid materials, rebar,
lumber, steel beams, and block wall
materials.
Perimeter controls at on-site inlets
and along south limit of facility.
Storage Area 14** Dump trucks, loaders, backhoes,
other large construction equipment.
Perimeter controls at on-site inlets
and along south limit of facility.
Large equipment as well as pickup
trucks and private vehicles will be
routinely inspected for leaks. Spill
kit must be available in case of
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leaks. Leaking vehicles will be
immediately removed from the
site.
Storage Area 15 Additional storage for materials as
described for Storage Areas 11-13
No BMPs required. This is a
covered storage area.
* All loading and unloading operations will be observed to ensure compliance with SWPPP.
**No fueling or large equipment/vehicle maintenance will be performed at the site.
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Figure 10 – SWPPS Plan
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5. Construction Stormwater Chemical Treatment – Construction stormwater will not
be generated at the site. Chemical treatment will not be required.
6. Construction Stormwater Filtration – No construction stormwater will be
generated at the site. Erosion control BMPs will be placed around all on-site
storm drain catch basins, the area in the southwest portion of the site where
stormwater will drain into the ditch along the east side of Lake Washington
Boulevard, and along the south perimeter of the site. These BMPs will capture
potential pollutants from the site before they are conveyed into the storm
drainage system.
7. High PH Neutralization Using CO2 – Materials and operations at the site will not
generate high Ph levels in stormwater. Neutralization will not be necessary.
8. PH Control for High PH Water - Materials and operations at the site are not
expected to generate high Ph levels in stormwater. Ph control will not be
necessary.
9. Use of High PH Soil Amendments on Construction Sites – There will be no
construction at the site on existing soil areas. Soil amendments will not be
necessary.
10. Maintain Protective BMPs – Erosion and stormwater control BMPs will be
maintained as per criteria to ensure proper performance and stormwater
protection. BMPs will be monitored, inspected, maintained and documented as
per the requirements of the CoR SWDM.
11. Manage the Project – SWPPP requirements will be implemented/managed as
part of the overall plan. Protective measures for on-site storage and operations
will be inspected, maintained, repaired/replaced, and documented as per CoR
requirements. Additional information on performance and compliance is provided
in Sections 8.4 and 8.5 of this CSWPPP.
8.4 CSWPP Performance and Compliance Provisions
8.4.1 CSWPP Supervisor
A CSWPP Supervisor will be designated for the site. The supervisor will be responsible
for the placement, performance, and maintenance to ensure compliance with the
requirements of the NPDES general stormwater permit. The supervisor will also
periodically review the ESC and SWPPS measures along with the on-going site
operations to determine if changes to BMPs or additional BMPs are required.
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The contact information for the CSWPP Supervisor is shown below:
Name: DJ Mosier
Address: dmosier@flatironcorp.com
Phone: Mobile 206-396-6289
Additional Compliance Inspectors, under the direct supervision of the CSWPP
Supervisor, are shown below:
Name: Forest Brown
Address: FBrown@FlatironLaneJV.com
Phone: Mobile 425-531-1228
Name: Zach Wallace
Address: ZWallace@FlatironLaneJV.com
Phone: Mobile 760-458-2675
Name: Jonathan Gates
Address:
Phone: Mobile 704-314-7757
8.4.2 Monitoring of Discharges
The CSWPP Supervisor will have a turbidity meter onsite. The supervisor or
compliance inspector will monitor turbidity values from stormwater discharges that are
affected by on-site activities. A log of all turbidity measurements will be kept on-site and
will be made available to the Community and Economic Development (CED)
Department upon request. Additional monitoring will be performed (if needed) as per
the requirements of the NPDES general stormwater permit.
8.4.3 ESC Performance
All BMP measures established at the site will be installed and maintained or
repaired/replaced to minimize the transport of sediments to May Creek and the existing
on-site stormwater conveyance system that discharges to May Creek, southwest of the
site. The performance of the BMPs depends on proper selection, installation, operation,
and maintenance as per CoR standards. During the construction of I-405
improvements, the CSWPP Supervisor may determine that approved ESC measures
are not sufficient to minimize the transport of sediments into May Creek or adjacent
existing stormwater systems. This would include the turbidity requirements as per the
CoR SWDM and/or changes to on-site operations that would require revisions or
additional BMPs to protect stormwater quality. The supervisor will modify the ESC Plan
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44th Street Field Offices and Laydown/Storage Area Page 46
to reflect changes to existing BMPs and/or the placement of additional BMPs as needed
for site operations or storage changes.
8.4.4 SWPPS Performance
BMPs established at the site are also installed and maintained to minimize the transport
of other potential pollutants to the existing stormwater system or to May Creek due to
the on-site activities and storage of materials. As with the ESC Plan, the supervisor
may determine that approved SWPPS measures are not sufficient to minimize the
transport of other potential pollutants into existing stormwater systems. If necessary,
the supervisor will modify the SWPPS to reflect changes to existing BMPs or the
placement of additional BMPs to ensure compliance with the general permit.
8.4.5 Flexible Compliance
Core Requirement #5 addresses the requirements for construction stormwater pollution
prevention. This requirement states that erosion and sediment controls, as well as
pollution prevention and spill controls, must be established for projects that will clear,
grade, or otherwise disturb construction sites. As discussed in earlier sections of this
report, there are no plans to modify the grading, land cover, or the existing stormwater
conveyance system throughout the site. The activities at the site include the
construction of temporary buildings for office space and areas where construction
materials, vehicles, and equipment will be stored.
Although there are no planned modifications to the topography, cover, or the storm
conveyance system at the site, the operations will require the use of on-site BMPs
throughout the duration of the I-405 project to prevent or minimize the discharge of
potential pollutants into the existing storm drainage system and May Creek. The BMPs
are discussed in this CSWPP Plan.
8.4.6 Roads and Utilities Compliance
The operations at the 44th Street facility do not involve the construction of roads and
utilities. The standards of Core Requirement #5 can be met using sediment/erosion
control BMPs and pollution/spill mitigation BMPs. As a result, no specific road or utility
compliance measures are necessary.
8.4.7 Alternative Measures
The BMPs established at this site are found and detailed in the CoR SWDM. Any
modifications to the BMPs found in the SWDM or the use of new products, as proposed
by the CSWPP Supervisor, will be submitted to the CoR for approval.
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8.5 CSWPP Implementation Requirements
8.5.1 CSWPP Plan
This CSWPP Plan contains both the ESC Plan and the SWPPS Plan and is described
in detail in the previous sections of this report. The plans will be kept on-site throughout
the duration of the I-405 construction. As outlined in the CoR SWDM, the CSWPP
report shall include the following:
1. Detailed Construction Sequence. This site is not part of the I-405 construction
and does not involve construction sequencing. The site provides temporary
office space and storage areas for construction materials.
2. Technical Information Report (TIR). This CSWPP Plan is part of the overall TIR
for this site.
3. Calculations. The BMPs proposed in the ESC and SWPPS Plans do not require
calculations for sizing.
4. Descriptions. Descriptions of operating procedures, precautions, data logging,
and reporting requirements will be provided as per the guidelines of the CoR
SWDM.
5. Inspection and Maintenance Program. A BMP inspection and maintenance
program, including the designation of the CSWPP Supervisor will be provided as
per the guidelines of the CoR SWDM and are outlined in this CSWPP.
6. Anticipated Changes or Additions. Any changes or additions to the ESC and
SWPPS plans will be noted in the plans and report by the CSWPP Supervisor to
ensure compliance with Core Requirement #5.
8.5.2 Wet Season Requirements
As discussed earlier in this report, there are no disturbed or exposed soil areas on the
site. The site is completely paved with asphalt with a small grass area near the
entrance. As a result, the site is not subject to wet season requirements. Sediments
from construction materials and equipment that are brought into the site will be
mitigated by the on-site BMPs shown in the ESC Plan.
8.5.3 Critical Areas Restrictions
The vicinity maps in the TIR as well as the existing site maps in the CSWPP show that
the southern limit of the site is adjacent to the north bank of May Creek. A small portion
of the site is within the regulatory 100-year floodplain for May Creek as shown in the
CSWPP figures. A small ditch/sump area is located in the southwest corner of the site
and is part of the Lake Washington Blvd. and on-site conveyance system. The 100-
year floodplain, along with this ditch/sump area, constitutes a Shoreline Buffer Area
(SBA) along the south side of the site. The SBA is shown in Figure 3 and Figures 8, 9,
and 10. A 5 foot offset north from the SBA will be marked on-site using High Visibility
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Fence and no on-site activities and material storage will occur past this fence. Silt
fence, or other perimeter controls will be established along this fence and sediment
control BMPs will be placed throughout the site to prevent potential pollutants from
entering May Creek, either directly from the south limit of the facility or through the
existing storm conveyance system.
The CSWPP Supervisor and site personnel will monitor precipitation forecasts. If heavy
rains are forecast, the water level in May Creek will be monitored. Floodwater from May
Creek may rise to a point where the southern portion of the facility is affected. If this
occurs, the materials stored just north of the SBA buffer will be monitored and moved
away from the high water if necessary. This will prevent these materials from being
washed into May Creek and will prevent potential pollutants from entering the
floodwaters.
As Figure 10 shows, storage areas 12 and 13 are located nearest to the SBA and could
be affected by potential floodwater from May Creek. The materials stored in these
areas will be moved, if needed, in the event of high water from May Creek.
8.5.4 Maintenance Requirements
All BMPs for the ESC Plan and the SWPPS Plan will be maintained, inspected, and
repaired/replaced as per the requirements of the CoR SWDM. This includes weekly
inspections of all on-site BMPs, and within 24 hours of significant precipitation events
(0.5” of rain in 24 hours or less). The CSWPP Supervisor or an employee designated
by the supervisor will observe major activities on the site including material deliveries
and on-site loading and unloading operations. Maintenance and operations review
reports will be kept on site throughout the duration of the I-405 project construction and
copies will be submitted to the CED upon request.
The form templates in the King County SWDM will be used and these are provided in
Section 10 of this TIR. Maintenance and operations guidelines are also shown in
Section 10.
8.5.5 Final Stabilization
Once construction of the I-405 project is complete, all remaining materials in the on-site
storage areas will be removed. After all stored materials are removed and the
temporary office buildings are disassembled, the ESC and SWPPS BMPs will be
removed. Existing catch basins and pipes will be inspected and cleaned if necessary.
Since there are no disturbed bare soil areas on the site, there is no need for vegetation
or other stabilization requirements.
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8.5.6 NPDES Requirements
This site does not disturb or create any existing or new soil areas. However, the site
does provide office space and equipment and material storage for the much larger I-405
project. In order to meet NPDES Requirements, a Construction Stormwater General
Permit (CSGP) was obtained for the overall I-405 project. Since this site is a part of the
overall project, a separate CSGP will not be required.
8.5.7 Forest Practice Permit Requirements
The operations at this site will require no clearing and grubbing of forest land. A Special
Forest Practice Permit is not required.
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Section 9 - Bond Quantities, Facility
Summaries, and Declaration of Covenant
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The Bond Quantity Spreadsheet is shown in Figure 11 below. According to the CoR
SWDM, a “Flow Control and Water Quality Facility Summary” is required for each facility
that is proposed for construction. Because this site does not disturb or create any
existing or new soil areas and is only used for temporary office space and as a
storage/laydown area, a “Flow Control and Water Quality Facility Summary” is not
required.
The CoR SWDM also discusses a required “Declaration of Covenant for Privately
Maintained On-Site BMPs”. This covenant is to be included in this section as per Core
Requirement #9. This core requirement states that on-site BMPs must be provided to
mitigate the impacts of storm and surface water runoff generated by new impervious
and pervious surfaces, existing impervious surfaces, and replaced impervious surfaces.
The site is exempt from this requirement if there is less than 2,000 square feet of new
plus replaced impervious surface created and less than 7,000 square feet of land
disturbing activities. As discussed for Core Requirement #5, the existing
pervious/impervious land cover at the site will not be modified, and the site is exempt
from this requirement based on the criteria listed. Although the site is exempt from this
core requirement, BMPs will be established on-site due to the increase in activity at the
site from office and staging/storage operations. A full CSWPP plan for this facility is
found in Section 8 of this report.
CED Permit #:########
Unit
Reference #Price Unit Quantity Cost
Backfill & compaction-embankment ESC-1 6.50$ CY
Check dams, 4" minus rock ESC-2 SWDM 5.4.6.3 80.00$ Each
Catch Basin Protection ESC-3 35.50$ Each 32 1,136.00
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 4800 7,200.00
Fence, Temporary (NGPE)ESC-8 1.50$ LF 5200 7,800.00
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 200 160.00
Interceptor Swale / Dike ESC-12 1.00$ LF
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
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
Plastic covering, 6mm thick, sandbagged ESC-20 SWDM 5.4.2.3 4.00$ SY 120 480.00
Rip Rap, machine placed; slopes ESC-21 WSDOT 9-13.1(2)45.00$ CY
Rock Construction Entrance, 50'x15'x1'ESC-22 SWDM 5.4.4.1 1,800.00$ Each 1 1,800.00
Rock Construction Entrance, 100'x15'x1'ESC-23 SWDM 5.4.4.1 3,200.00$ Each
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 675 12,825.00
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 832 91,520.00
Water truck, dust control ESC-31 SWDM 5.4.7 140.00$ HR
Unit
Reference #Price Unit Quantity Cost
25.00$ Each 260 6,500.00
EROSION/SEDIMENT SUBTOTAL:129,421.00
SALES TAX @ 10%12,942.10
EROSION/SEDIMENT TOTAL:142,363.10
(A)
SITE IMPROVEMENT BOND QUANTITY WORKSHEET
FOR EROSION & SEDIMENT CONTROL
Description No.
(A)
Concrete Ecology Blocks
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: 04/26/2017
Printed 3/25/2021
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Figure 11 – Bond Quantity Spreadsheet (continued)
Page Purposely Left Blank
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Section 10 - Operations and Maintenance
Manual
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All BMPs for the ESC Plan and the SWPPS Plan will be maintained and inspected as
per the requirements of the CoR SWDM. In general, maintenance procedures for each
ESC Plan BMP used at the site are as follows:
1. All on-site BMPs will be inspected weekly and within 24 hours of significant
precipitation events (0.5” of rain in 24 hours or less). BMPs found to be
damaged will be repaired or replaced as soon as possible after the inspection.
2. Sediments that accumulate around the catch basin protection structures or
behind silt fences will be removed immediately. After sediments are removed,
damaged BMPs will be immediately repaired or replaced.
The CSWPP Supervisor or an employee designated by the supervisor will perform BMP
inspections and will make recommendations for maintenance, repair, and/or
replacement of the BMP. The supervisor or designated employee will also observe
major activities on the site including on-site loading and unloading operations, material
storage areas, and good housekeeping practices.
Installation, inspection, and maintenance form templates are provided in Section 10.1
below. Installation specification and maintenance requirements for ESC Plan BMPs are
provided in Section 10.2. Guidelines for SWPPS Plan BMPs are shown in Section 10.3.
The forms and guidelines were copied from the King County SWDM (Reference 4) and
are provided in these sections. Further detailed information, if needed, can be found in
the CoR and King County SWDM documents. All inspection and maintenance forms
will be kept on site and copies will be submitted to the CED upon request. Standard
maintenance reports will be kept on-site throughout the duration of the I-405 project
construction.
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10.1 Implementation, Installation, Inspection, and
Maintenance Forms
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10.2 Installation Specifications and Maintenance
Requirements – ESC Plan BMPs
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10.3 Guidelines for SWPPS Plan BMPs
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References
1. City of Renton, Washington. Maps and GIS Data. City Hall, Administrative
Services, Information Technology. 1055 South Grady Way, Renton, Washington,
98057.
2. City of Renton Surface Water Design Manual. City of Renton, Public Works
Department, Surface Water Utility. December 12, 2016.
3. King County Stormwater Pollution Prevention Manual, Best Management
Practices for Commercial, Multi-Family, and Residential Properties. Department
of Natural Resources and Parks, Water and Land Resources Division,
Stormwater Services Section. April 2016.
4. King County Surface Water Design Manual, King County Department of Natural
Resources and Parks. April 24, 2016.
5. United States Department of Agriculture, Natural Resources Conservation
Service (NRCS). Web Soil Survey, National Soil Survey Center, Lincoln, NE
68508.