HomeMy WebLinkAboutTIR-3820IEC
INSIGHT ENGINEERING CO.
TECHNICAL INFORMATION REPORT
For
LEGACY RENTON
Prepared for
City of Renton
Renton City Hall - 6th Floor
1055 South Grady Way
Renton, WA 98057
Certified Erosion and Sedimentation Control Lead:
To be named by contractor
Stormwater Site Plan Prepared By:
Jacob D. Mealey, E.I.T.
TIR Preparation Date:
December 19, 2014
Approximate Construction Date:
May 1, 2015
P.O Box 1478 • Everett, WA 98206 • P: 425.303.9363
F: 425.303.9362 • info@insightengineering.net
/1- Zz-�y
Project Site Location:
1300
Lake Washington Boulevard N.
Renton, WA 98056
Applicant:
Contact:
Legacy Hospitality, Inc.
IECO
6501 America's Parkway NE -Suite 1050
P.O. Box 1478
Albuquerque, NM 87110
Everett, WA 98206
Contact: Fazel Kassam
425-303-9363
Ph. (505)243-6000
Tax Id: 3344500007
File # : -
IECO Project: 13-0623
Certified Erosion and Sedimentation Control Lead:
To be named by contractor
Stormwater Site Plan Prepared By:
Jacob D. Mealey, E.I.T.
TIR Preparation Date:
December 19, 2014
Approximate Construction Date:
May 1, 2015
P.O Box 1478 • Everett, WA 98206 • P: 425.303.9363
F: 425.303.9362 • info@insightengineering.net
/1- Zz-�y
TABLE OF CONTENTS
1.0 Project Overview....................................................................................................................3
2.0 Condition of Approval..........................................................................................................5
3.0 Offsite Analysis.......................................................................................................................9
3.1 Upstream Analysis.......................................................................................................................
9
3.2 Downstream Analysis..................................................................................................................9
4.0 Core and Special Requirements..........................................................................................12
5.0 Flow Control and Water Quality Analysis..........................................................................14
5.1 Developed Basin Summary........................................................................................................14
5.2 Frontage Basin Summary...........................................................................................................15
5.3 Water Quality.............................................................................................................................15
6.0 Conveyance Analysis and Design.......................................................................................17
7.0 Erosion/Sedimentation Control Design.............................................................................18
8.0 Appendix..............................................................................................................................18
Figures
Figure1 - Vicinity Map.................................................................................................................4
Figure2 - Soil Map........................................................................................................................6
Figure3 - Downstream Analysis Map......................................................................................11
Insight Engineering Co. - Stormwater Site Plan 12/19/14
-1-
Acronyms and Abbreviations
BMP
Best Management Practices
DOE
Department of Ecology
EDDS
Engineering Design and Development Standards
ESC
Erosion and Sediment Control
IECO
Insight Engineering Company
MR
Minimum Requirement
SCDM
Snohomish County Drainage Manual
SWPPP
Stormwater Pollution Prevention Plan
SWMMWW
Stormwater Management Manual for Western Washington
TESC
Temporary Erosion and Sediment Control
WWHM
Western Washington Hydrology Model
Insight Engineering Co. - Stormwater Site Plan
-2-
12/19/14
1.0 Project Overview
The proposed project "Legacy Renton" is located at 1300 Lake Washington Boulevard
N. in King County, Washington. More generally, the project site is located in Section 6,
Township 23 North, and Range 5 East of the Willamette Meridian in King County, Washington.
Please refer to the Vicinity Map attached later in the section. This report will follow the
Technical Information Report requirements, per 2009 King County Surface Water Design
Manual.
The project contains 1.31 Acres. The site is currently developed with a small building
with an asphalt drive aisle. The remainder of the site exists as a combination of grassy and
forested areas. The site contains one drainage basin that slopes to the southwest. Please refer to
the downstream analysis map for more details. There are no critical areas located on the site. Per
SCC survey of King County, the project site contains AkF (Alderwood and Kitsap soils, very
steep). Please refer to the soils map and descriptions attached later in this report for more details.
The proposal is to construct new hotel, parking garage and approximately 175-1f of
asphalt drive aisle for access with associated utilities. The access for the site will be from Lake
Washington Blvd. N.
The project is located within the Lake Washington E drainage basin and is not subject to
special runoff detention and flow controls. The proposal includes a tight lined connection to the
15 -inch pipe that runs underneath Lake Washington Blvd. N. located north of the project site.
The capacity of the downstream path was analyzed to determine if the downstream system was
capable of accepting the 100 -yr storm event flows for the entire upstream basin. Refer to section
VI — Conveyance Analysis and Design for a detailed conveyance of the downstream system. The
project is exempt for water quality because the total pollution generating impervious surfaces
(PGIS) is 3,982 SF which is less than the threshold of 5,000 SF per section 1.2.8 of the
KCSWDM. All covered parking areas will be connected to the sanitary sewer.
Insight Engineering Co. - Stormwater Site Plan
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12/19/14
FIGURE]. VICINITY MAP
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INSIGHT ENGINEERING CO.
P.O. Box 1478 Everett, WA 98206
425-303-9363, 425-303-9362 f.
Info@insightengineering.net
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Figure 1 -Vicinity Map
Legacy Renton
Renton, Washington
SCALE: DATE: 12/19/14 JOB #: 13-0623
NTS
FILE NAME:
BY: JDM 13-0623/doc/drainage report
Insight Engineering Co. - Stormwater Site Plan 12/19/14
-4-
2.0 Conditions of Approval
The conditions of approval will be forthcoming.
Insight Engineering Co. - Stormwater Site Plan
-5-
12/19/14
Insight Engineering Co. - Stormwater Site Plan
MGM
12/19/14
King County Area, Washington
AkF Alderwood and Kitsap soils, very steep
Map Unit Setting
• Elevation: 50 to 800 feet
• Mean annual precipitation: 25 to 60 inches
• Mean annual air temperature: 48 to 52 degrees F
• Frost -free period: 160 to 220 days
Map Unit Composition
• Alderwood and similar soils: 50 percent
• Kitsap and similar soils: 25 percent
Description of Alderwood
Settine
• Landform: Moraines, till plains
• Parent material: Basal till with some volcanic ash
Properties and qualities
• Slope: 25 to 70 percent
• Depth to restrictive feature: 24 to 40 inches to densic material
• 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
• Frequencyofflooding. None
• Frequency ofponding. None
• Available water capacity: Very low (about 2.5 inches)
Interpretive croups
• Farmland classification: Not prime farmland
• Land capability (nonirrigated): 7e
• Hydrologic Soil Group: B
Typical profile
• 0 to 12 inches: Gravelly ashy sandy loam
• 12 to 27 inches: Very gravelly sandy loam
• 27 to 60 inches: Very gravelly sandy loam
Description of Kitsap
Settin
• Landform: Terraces
• Parent material: Lacustrine deposits with a minor amount of volcanic ash
Properties and aualities
• Slope: 25 to 70 percent
• Depth to restrictive feature: More than 80 inches
• Drainage class: Moderately well drained
• Capacity of the most limiting layer to transmit water (Ksat): Moderately low to moderately high (0.06 to
0.20 in/hr)
Insight Engineering Co. - Stormwater Site Plan
-7-
12/19/14
• Depth to water table: About 18 to 36 inches
• Frequency offlooding. None
• Frequency ofponding. None
• Available water capacity: High (about 11.4 inches)
Interpretive groups
• Farmland classification: Not prime farmland
• Land capability (nonirrigated): 7e
• Hydrologic Soil Group: C
Typical profile
• 0 to S inches: Ashy silt loam
• S to 24 inches: Ashy silt loam
• 24 to 60 inches: Stratified silt to silty clay loam
King County Area, Washington
Ur—Urban land
Map Unit Composition
• Urban land: 100 percent
Description of Urban Land
Interpretive groups
• Farmland classification: Not prime farmland
• Land capability (nonirrigated): 8
Insight Engineering Co. - Stormwater Site Plan
-8-
12/19/14
3.0 Offsite Analysis
A site reconnaissance was performed by Brian R. Kalab of Insight engineering on
November 23, 2013 to verify the downstream flow paths and observe any drainage problems
downstream of the site. The sky was overcast with a temperature of 45 degrees.
The project contains 1.31 Acres. The site is currently developed with a small building
with an asphalt drive aisle. The remainder of the site exists as a combination of grassy and
forested areas. The site contains one drainage basin that slopes to the southwest.
3.1 Upstream Analysis
Based on the site reconnaissance and the topographic survey of the site, the upstream
flows appear to be minimal. Refer to the Downstream Analysis Map attached in the next page for
more details.
3.2 Downstream Analysis
Refer to the Downstream Analysis Maps 1 and 2 attached to the next pages for a visual
description of the downstream flow.
Existing Conditions
The existing site appears to drain to the southwest of the project site and then travels
south along Lake Washington Blvd. N. The drainage continues to travel south and crosses
railroad tracks and a roadway and enters a slight depression. The drainage continues south
underneath roadway via a 12" dia. culvert. The drainage then travels southwest along a roadside
ditch along Lake Washington Blvd. where it then travels northwest underneath Lake Washington
Blvd. N. via four separate culverts (two 54" dia. and two 48" dia. culverts). The drainage then
travels northeast within a roadside ditch along Lake Washington Blvd. N and then travels
northwest underneath railroad tracks via several culverts. The flows continue to flow northwest
through a ditch and then underneath a roadway via several culverts. The drainage flows north
and then enters a box culvert that flows to the north to a stream that eventually discharges to
Insight Engineering Co. - Stormwater Site Plan
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12/19/14
Lake Washington. This is where the 1 mile downstream observations were stopped. It is our
understanding that there is theoretical 100 year flooding at the box culvert. Because of this
flooding and the lack of a downstream conveyance system the proposed downstream from the
site will be redirected as described in the developed conditions below.
Developed Conditions
The proposed discharge from the site (developed basin -1) will be connected to the exiting
15" pipe that runs underneath Lake Washington Blvd. N located to the north of the proposed
project. The proposed system includes a 12" dia. system that travels underneath Lake
Washington Blvd. N and then north along Lake Washington Blvd. N for approximately 215 -ft.
From the point where the drainage is connected to the existing 15" pipe, the pipe flows west for
approximately 20 additional feet before discharging to an open channel system. The open
channel conveys the flows south for about 120 feet, parallel to the road and railroad tracks. The
open channel is comprised of 4 to 6 inches of quarry spalls, and is approximately 2 to 3 feet wide
and 18 inches deep, with 3 to 1 side slopes. The channel flows into a 24 inch CMP culvert that
conveys the water to the west under the railroad tracks, through a catch basin and into another 24
inch CMP pipe. The outfall from the pipe flows into Johns Creek which flows to the west and
discharges into Lake Washington. This is where the downstream analysis was completed. There
did not appear to be any restrictions or erosion problems downstream of the site. The developed
downstream discharges within'/4 mile of the natural downstream condition and is in the same
threshold discharge area.
A small portion of the developed site (developed basin -2) will continue its existing
drainage path. About 3,765 SF of the developed site will be contained within this basin. This
area will continue this drainage path because of elevation constraints. This portion of the site
could not be conveyed to the north along with the majority of the site. The overall runoff for the
existing drainage course will be less because the entire developed basin -1 will be redirected to
the north and will no longer flow to the south.
Insight Engineering Co. —Technical Information Report
-10-
12/19/14
FIGURE 3. DOWNSTREAM ANALYSIS MAP
Figure 3 - Downstream Analysis Map
Legacy Renton
Renton, Washington
INSIGHT ENGINEERING CO.
P.O. Box 1478 Everett, WA 98206 SCALE: DATE: 12/22/14 JOB #: 13-0623
425-303-9363, 425-303-9362 f. NONE
Info@insightengineering.net FILE NAME:
BY: JDM 13-0623\docs\drainage report
Insight Engineering Co. — Technical Information Report
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12/19/14
4.0 Core and Special Requirements
1.2.1 Core Requirement #1: Discharge at the Natural Location
The proposed project's storm water will be discharged to the drainage system within Lake
Washington Blvd N. at the southwest corner of the site to follow its natural location.
1.2.2 Core Requirement 42: Off-site Analysis
Refer to Section 3 for the level one downstream analysis.
1.2.3 Core Requirement #3: Flow Control
The project is located within the Lake Washington E drainage basin and is not subject to special
runoff detention and flow controls. The proposal includes a tight lined connection to the 15 -inch
pipe that runs underneath Lake Washington Blvd. N. located north of the project site. The
capacity of the downstream path was analyzed to determine if the downstream system was
capable of accepting the 100 -yr storm event flows for the entire upstream basin. Refer to section
VI — Conveyance Analysis and Design for a detailed conveyance of the downstream system.
The following conditions need to be met before direct discharge can be accepted. The conditions
are summarized with our answers to the conditions italicized.
a) The flowpath from the project site discharge point to the edge of the 100 -year floodplain of
the major receiving water will be no longer than one-half mile, except for discharges to
Lake Washington, AND
The flowpath from the proposed downstream is less than % mile from the project site to the
receiving water body.
b) The conveyance system between the project site and the major receiving water will extend
to the ordinary high water mark, and will be comprised of manmade conveyance elements
(pipes, ditches, etc,) and will be within public right-of-way or a public or private drainage
easement, AND
The conveyance system will be entirely within public right of ways and public park
conveyance systems.
c) The conveyance system will have adequate capacity to convey the 25 -year peak flow (per
Core Requirement #4, Conveyance System) for the entire contributing drainage area,
assuming build -out conditions to current zoning for the equivalent area portion (defined in
Figure 1.2.3.A, below) and existing conditions for the remaining area, AND
The entire basin will be built out, with the construction of this proposal. Two previous
upstream projects have calculated the downstream capacity of the conveyance system. We
have used these previous calculations and added the current proposal to the model. The
downstream conveyance system has enough capacity to pass the 100 year storm. Please
see the conveyance system calculations in section 6.0 of this report.
Insight Engineering Co. — Technical Information Report 12/19/14
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d) The conveyance system will be adequately stabilized to prevent erosion, assuming the same
basin conditions as assumed in Criteria (c) above, AND
The conveyance system is adequately stabilized to prevent erosion for the entire basin
flows.
e) The direct discharge proposal will not divert flows from or increase flows to an existing
wetland or stream sufficient to cause a significant adverse impact.
The discharge will not divert any flows from a wetland and will actually decrease flows to
a known problem in the natural downstream system.
1.2.4 Core Requirement #4: Conveyance System
Site runoff will be collected by means of yard drains, catch basins and roof drains. Collected
runoff will be conveyed to the within pipelines designed to 25 -year peak flows and checked for
flooding conditions at the 100 year event.
1.2.5 Core Requirement #5: Erosion and Sediment Control
During construction of the infrastructure for Legacy Renton hotel, temporary erosion control
methods will be implemented to prevent sedimentation and erosion using those methods as
outlined in section 1.2.5.1 of the KCSWDM.
1.2.6 Core Requirement #6: Maintenance and Operations
This requirement will be fulfilled by the property owner until bonds have been released and
public drainage system(s) have been conveyed to City of Renton.
1.2.7 Core Requirement #7: Financial Guarantees and Liability
Bond and insurance in accordance with City of Renton requirements will be provided by or at the
behest of the owner during site construction and until the drainage facilities in public street
rights-of-way have been accepted by City of Renton for ownership.
1.2.8 Core Requirement #8: Water Quality
The project is exempt for water quality because the total pollution generating impervious
surfaces (PGIS) is 3,982 SF which is less than the threshold of 5,000 SF per section 1.2.8 of the
KCSWDM.
Insight Engineering Co. — Technical Information Report
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12/19/14
Special Requirements — Section 1.3 of KCSWDM
1.3.1 Special Requirement #1: Other Adopted Area Specific Requirements
Not applicable to this project
1.3.2 Special Requirement #2: Flood Plain / Floodway Delineation
Not applicable to this project
1.3.3 Special Requirement 93: Flood Protection Facilities
Not applicable to this project
1.3.4 Special Requirement 44: Source Controls
Not applicable to this project
1.3.5 Special Requirement #5: Oil Control
Not applicable to this project
Insight Engineering Co. — Technical Inforination Report
-14-
12/19/14
5.0 Flow Control and Water Quality Analysis and Design
The site contains one drainage basin that sheet flows to the southwest across the property and
enters into the existing storm drainage system on Lake Washington Blvd N.
Total site area = 1.31 Acres
Offsite frontage Area = 0.07 Acres
Existing Road = 0.08 Acres
Area Included in the Analysis = 1.46 Acres
5.1 Developed Basin -1 Summary
The proposed analysis parameters are as follows:
KCRTS methodology with level 1 flow control and 15 minute time -step
Seatac Rainfall region with a scale factor of 1.0.
Alderwood and Kitsap Soils have a hydrologic classification of "C". This corresponds to Till
soils of AkF soil group.
Developed Conditions Basin:
Portion of site area = 1.26 Acres
Offsite frontage Area = 0.04 Acres
Existiniz Road = 0.08 Acres
Area Included in the Analysis =1.38 Acres
Impervious area:
Roof area
= 0.39 Acres (17,015 SF)
Interior road
= 0.07 Acres (2,950 SF)
Walkways
= 0.05 Acres (2,295 SF)
Existing Road
= 0.08 Acres (3,640 SF)
Total Impervious
= 0.61 Acres
Pervious Areas = 0.77 Acres
Refer to the Developed Basin Map and the following pages for more details.
Insight Engineering Co. —Technical Inforrnation Report 12/19/14
-15-
5.2 Developed Basin -2 Summary
Developed Baisn-2 = 3,765 SF (0.08 Acres)
Impervious Areas:
Frontage Road and Sidewalk Improvements
Interior Road
Total Impervious
Pervious Areas = 0.05 Acres
Insight Engineering Co. — Technical Information Report
-16-
= 1,041 SF (0.03 Acres)
= 504 SF (0.01 Acres)
= 1,545 SF (0.03 Acres)
12/19/14
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5.3 Water Quality
The project is exempt for water quality because the total pollution generating impervious
surfaces (PGIS) is 3,982 SF which is less than the threshold of 5,000 SF per section 1.2.8 of the
KCSWDM. Refer to the following page for the Perk Filter calculation sheet.
Insight Engineering Co. —Technical Information Report 12/19/14
-17-
6.0 Conveyance Analysis and Design
Onsite Conveyance
A 100 -yr conveyance analysis was performed for the exiting downstream 15 -inch pipe. The
existing 100 -yr runoff flows that is currently conveyed through the exiting 15 -inch pipe have
been calculated and are presented within the TIR's for the Kennydale Cafe and the "The Bluffs"
Phase 2. The 100 -yr runoff flow from the Kennydale Cafe is 0.46 cfs, and the 100 -yr runoff
flow from "The Bluffs" Phase 2 is 5.21 cfs. The TIR's for each project has been included
within the appendix of this report. Using the Seatac Rainfall region with a scale factor of 1.0 and
15 -minute time -step, the 100 -yr runoff flow for the proposed project was determined to be 1.11
cfs. Therefore, the total flow through the 15 -inch pipe will be 6.78 cfs. The conveyance analysis
was performed by FlowMaster by Haestad Methods, Inc. Per the analysis, the 15 -inch pipe will
be able to convey the 100 -yr combined flows and will only have a depth of 5.6 inches within the
15 -inch pipe. The 24 -inch downstream pipe was also analyzed. With a slope of 3.83 percent, the
depth of the water for the 100 -yr storm event will only be 6.3 inches within the 24 -inch pipe.
Refer to the following pages for the detailed analysis.
Insight Engineering Co. — Technical Information Report 12/19/14
-18-
Page 1
Convey.pks
Flow Frequency Analysis
Time series
File:convey.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
0.291
6
8/27/01 18:00
1.11
1
100.00
0.990
0.227
8
1/05/02 15:00
0.718
2
25.00
0.960
0.718
2
12/08/02 17:15
0.490
3
10.00
0.900
0.234
7
8/23/04 14:30
0.419
4
5.00
0.800
0.490
3
11/17/04 5:00
0.375
5
3.00
0.667
0.375
5
10/27/05 10:45
0.291
6
2.00
0.500
0.419
4
10/25/06 22:45
0.234
7
1.30
0.231
1.11
1
1/09/08 6:30
0.227
8
1.10
0.091
Computed
Peaks
0.978
50.00
0.980
Page 1
Legacy Renton- Pipe Capacity 24"
Worksheet for Circular Channel
Project Description
Project File
r:\jobs\_2013 jobs - 593 -637\13-0623 legacy renton\documents\legacy r.fm2
Worksheet
pipe capacity
Flow Element
Circular Channel
Method
Manning's Formula
Solve For
Channel Depth
Input Data
Mannings Coefficient 0.013
Channel Slope 3.8300%
Diameter 24.00 in
Discharge 6.78 cfs
Results
Depth
6.3
in
Flow Area
0.66
ft2
Wetted Perimeter
2.16
ft
Top Width
1.76
ft
Critical Depth
0.92
ft
Percent Full
26.45
Critical Slope
0.004731 ft/ft
Velocity
10.20
ft/s
Velocity Head
1.62
ft
Specific Energy
2.14
ft
Froude Number
2.93
Maximum Discharge
47.62
cfs
Full Flow Capacity
44.27
cfs
Full Flow Slope
0.000898 ft/ft
Flow is supercritical.
12/19/14 FlowMaster v5.15
02:21:50 PM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755-1666 Page 1 of 1
Legacy Renton- Pipe Capacity 15"
Worksheet for Circular Channel
Project Description
5.6
Project File
r:\jobs\_2013 jobs - 593 -637\13-0623 legacy renton\documents\legacy r.fm2
Worksheet
pipe capacity
Flow Element
Circular Channel
Method
Manning's Formula
Solve For
Channel Depth
Input Data
Mannings Coefficient 0.013
Channel Slope 12.3000%
Diameter 15.00 in
Discharge 6.78 cfs
Results
Depth
5.6
in
Flow Area
0.42
ftZ
Wetted Perimeter
1.65
ft
Top Width
1.21
ft
Critical Depth
1.05
ft
Percent Full
37.51
Critical Slope
0.010631 ft/ft
Velocity
16.13
ft/s
Velocity Head
4.04
ft
Specific Energy
4.51
ft
Froude Number
4.82
Maximum Discharge
24.37
cfs
Full Flow Capacity
22.65
cfs
Full Flow Slope
0.011017
ft/ft
Flow is supercritical.
12/19/14 FlowMaster v5.15
02:22:21 PM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755-1666 Page 1 of 1
7.0 Erosion/ Sedimentation Control Design
Erosion and sedimentation control will be provided by utilization BMPs selected from the
2009 King County Surface Water Design Manual. These BMPs will likely include, but are not
necessarily limited to, sediment pond(s) and/or trap(s), silt fencing, construction safety fencing,
interceptor v -ditches, rock check dams, plastic sheeting of stockpiles, straw mulch, hydro -
seeding, catch basin protection, and rocked construction entrance, etc.
Refer to the Temporary Sedimentation and Erosion Control Plan attached in the
construction documents detailing the means by which sediment and erosion control will be
handled during construction.
Refer to the following pages for SWPPP.
Insight Engineering Co. — Technical Information Report 12/19/14
-19-
Stormwater Pollution Prevention Plan
Stormwater Pollution Prevention Plan
Owner
Legacy Hospitality, Inc.
6501 America's Parkway NE -
Suite 1050
Albuquerque, NM 87110
For
LEGACY RENTON
Prepared For
City of Renton
Renton City Hall - 6th Floor
1055 South Grady Way
Renton, WA 98057
Developer
Legacy Hospitality, Inc.
6501 America's Parkway NE -
Suite 1050
Albuquerque, NM 87110
Project Site Location
1300 Lake Washington Boulevard N.
Renton, WA 98056
Operator/Contractor
Certified Erosion and Sediment Control Lead
Contractor to provide
SWPPP Prepared By
Insight Engineering Company (IECO)
PO Box 1478
Everett, WA, 98206
425-303-9363
SWPPP Preparation Date
January 16, 2014
Approximate Project Construction Dates
May 1, 2014
Stormwater Pollution Prevention Plan
Contents
1.0 Introduction..............................................................................................................................1
2.0 Site Description........................................................................................................................ 3
2.1
Existing Conditions........................................................................................................... 3
2.2
Proposed Construction Activities......................................................................................3
6.0 Site Inspections and Monitoring.............................................................................................21
3.0 Construction Stormwater BMPs...............................................................................................5
6.1 Site Inspection.................................................................................................................21
3.1
The 12 BMP Elements......................................................................................................
5
6.1.2 Site Inspection Documentation......................................................................22
3.1.1 Element # 1 —Mark
Clearing Limits................................................................ 5
22
3.1.2 Element #2 —
Establish Construction Access ..................................................
5
3.1.3 Element #3 —
Control Flow Rates.................................................................... 6
7.1 Recordkeeping.................................................................................................................24
3.1.4 Element #4 —
Install Sediment Controls..........................................................
6
7.1.2 Records Retention..........................................................................................24
3.1.5 Element #5 —
Stabilize Soils............................................................................8
3.1.6 Element #6 —
Protect Slopes............................................................................9
3.1.7 Element #7 —
Protect Drain Inlets....................................................................
9
3.1.8 Element #8 —
Stabilize Channels and Outlets................................................10
3.1.9 Element #9 —
Control Pollutants....................................................................10
3.1.10 Element #10
— Control Dewatering...............................................................13
3.1.11 Element # 11
—Maintain BMPs.....................................................................13
3.1.12 Element #12
— Manage the Project................................................................13
3.2
Site Specific BMPs.........................................................................................................16
3.3
Additional Advanced BMPs...........................................................................................16
4.0 Construction Phasing and BMP Implementation...................................................................17
5.0 Pollution Prevention Team......................................................................................................19
5.1 Roles and Responsibilities..............................................................................................19
5.2 Team Members................................................................................................................20
6.0 Site Inspections and Monitoring.............................................................................................21
6.1 Site Inspection.................................................................................................................21
6.1.1 Site Inspection Frequency.............................................................................21
6.1.2 Site Inspection Documentation......................................................................22
6.2 Stormwater Quality Monitoring......................................................................................
22
6.2.1 Turbidity........................................................................................................
22
6.2.2 pH..................................................................................................................23
7.0 Reporting and Recordkeeping................................................................................................
24
7.1 Recordkeeping.................................................................................................................24
7.1.1 Site Log Book................................................................................................24
7.1.2 Records Retention..........................................................................................24
7.1.3 Access to Plans and Records.........................................................................24
Ifi
Stormwater Pollution Prevention Plan
7.1.4
Updating the SWPPP.....................................................................................24
7.2 Reporting
.........................................................................................................................25
7.2.1
Discharge Monitoring Reports......................................................................25
7.2.2
Notification of Noncompliance.....................................................................25
7.2.3
Permit Application and Changes...................................................................
26
AppendixA
— Site Plans......................................................................................................267
Appendix B
— Construction BMPs.........................................................................................28
Appendix C
— Alternative BMPs............................................................................................29
Appendix D
— General Permit................................................................................................30
Appendix E —
Site Inspection Forms (and Site Log)
..............................................................31
Appendix F —
Engineering Calculations................................................................................33
Om
Stormwater Pollution Prevention Plan
1.0 Introduction
This Stormwater Pollution Prevention Plan (SWPPP) has been prepared as part of the
Construction stormwater permit requirements for the Legacy Renton in Renton, Washington.
The site is located at 1300 Lake Washington Boulevard N. in King County, Washington. The site
is currently developed with a small building with an asphalt drive aisle. The remainder of the site
exists as a combination of grassy and forested areas. The site contains one drainage basin that
drains to the west. Per Soils Survey of King County area, the majority of the project site contains
AkF (Alderwood and Kitsap soils, very steep) soils. The project contains approximately 1.31
acres. The proposal is to construct new hotel, parking garage and approximately 300-1f of asphalt
road for access with associated utilities. The access for the site will be from Lake Washington
Blvd. N.
The purpose of this SWPPP is to describe the proposed construction activities and all temporary
and permanent erosion and sediment control (TESC) measures, pollution prevention measures,
inspection/monitoring activities, and recordkeeping that will be implemented during the
proposed construction project. The objectives of the SWPPP are to:
1. Implement Best Management Practices (BMPs) to prevent erosion and
sedimentation, and to identify, reduce, eliminate or prevent stormwater
contamination and water pollution from construction activity.
2. Prevent violations of surface water quality, ground water quality, or
sediment management standards.
3. Prevent, during the construction phase, adverse water quality impacts
including impacts on beneficial uses of the receiving water by controlling
peak flow rates and volumes of stormwater runoff at the Permittee's
outfalls and downstream of the outfalls.
This SWPPP was prepared using the Ecology SWPPP Template downloaded from the Ecology
website on February 19, 2007. This SWPPP was prepared based on the requirements set forth in
the Construction Stormwater General Permit and in the Stormwater Management Manual for
Western Washington (SWMMWW 2005). The report is divided into seven main sections with
several appendices that include stormwater related reference materials. The topics presented in
the each of the main sections are:
■ Section 1 — INTRODUCTION. This section provides a summary
description of the project, and the organization of the SWPPP document.
■ Section 2 — SITE DESCRIPTION. This section provides a detailed
description of the existing site conditions, proposed construction activities,
Stormwater Pollution Prevention Plan
and calculated stormwater flow rates for existing conditions and post—
construction conditions.
■ Section 3 — CONSTRUCTION BMPs. This section provides a detailed
description of the BMPs to be implemented based on the 12 required
elements of the SWPPP (SWMMEW 2004).
■ Section 4 — CONSTRUCTION PHASING AND BMP
IMPLEMENTATION. This section provides a description of the timing
of the BMP implementation in relation to the project schedule.
■ Section 5 — POLLUTION PREVENTION TEAM. This section identifies
the appropriate contact names (emergency and non -emergency),
monitoring personnel, and the onsite temporary erosion and sedimentation
control inspector
■ Section 6 — INSPECTION AND MONITORING. This section provides a
description of the inspection and monitoring requirements such as the
parameters of concern to be monitored, sample locations, sample
frequencies, and sampling methods for all stormwater discharge locations
from the site.
■ Section 7 — RECORDKEEPING. This section describes the requirements
for documentation of the BMP implementation, site inspections,
monitoring results, and changes to the implementation of certain BMPs
due to site factors experienced during construction.
Supporting documentation and standard forms are provided in the following Appendices:
Appendix A — Site plans
Appendix B — Construction BMPs
Appendix C — Alternative Construction BMP list
Appendix D — General Permit
Appendix E — Site Log and Inspection Forms
Appendix F — Engineering Calculations
2
2.0
2.1 Existing Conditions
Stormwater Pollution Prevention Plan
Site Description
The proposed project "Legacy Renton" is located at 1300 Lake Washington Boulevard N. in
King County, Washington. More generally, the project site is located in Section 6, Township 23
North, and Range 5 East of the Willamette Meridian in King County, Washington. The project
contains approximately 1.31 acres. The proposal is to construct new hotel, parking garage and
approximately 300-1f of asphalt road for access with associated utilities. The access for the site
will be from Lake Washington Blvd. N. The site contains one drainage basin that drains to the
west. Per Soils Survey of King County area, the majority of the project site contains AkF
(Alderwood and Kitsap soils, very steep) soils.
2.2 Proposed Construction Activities
The proposal is to construct new hotel, parking garage and approximately 300-1f of asphalt road
for access with associated utilities. The access for the site will be from Lake Washington Blvd.
N. The project will provide a 52'x 24'x 10.5' underground vault located underneath the drive
aisle is proposed to meet the flow control requirements conforming to the 2009 KCSWDM and
the city of Renton's requirements. A stormfilter manufactured by Contech Engineered solutions
is proposed downstream of detention to provide adequate water quality. The outflow from the
detention facility will be tight lined to the existing storm system on Lake Washington Blvd. N to
continue its natural drainage path. The following summarizes details regarding site areas:
■ Project development area:
■ Percent impervious area before construction:
■ Percent impervious area after construction:
■ Disturbed area during construction:
■ Disturbed area that is characterized as impervious (i.e.,
access roads, staging, parking):
■ 2 -year stormwater runoff peak flow prior to construction
(existing):
3
1.31 acres
<5%
80%
1.31 acres
1.03 acres
0.04 cfs
Stormwater Pollution Prevention Plan
■ 10 -year stormwater runoff peak flow prior to construction
(existing): 0.07 cfs
■ 2 -year stormwater runoff peak flow during construction: 0.28 cfs
■ 10 -year stormwater runoff peak flow during construction: 0.34 cfs
■ 2 -year stormwater runoff peak flow after construction: 0.04 cfs
■ 10 -year stormwater runoff peak flow after construction: 0.07 cfs
All stormwater flow calculations are provided in Appendix F.
4
Stormwater Pollution Prevention Plan
3.0 Construction Stormwater BMPs
3.1 The 12 BMP Elements
3.1.1 Element #1— Mark Clearing Limits
To protect adjacent properties and to 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:
• High Visibility Plastic or Metal Fence (BMP C103)
Install orange barrier fencing along the clearing limits, according to the approved
construction plans, prior to any construction activities. Maintain until all
construction activities are completed.
Alternate BMPs for marking clearing limits are included in Appendix C 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 C after the first sign that existing BMPs are
ineffective or failing.
3.1.2 Element #2 — Establish Construction Access
Construction access or activities occurring on unpaved areas shall 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. The
specific BMPs related to establishing construction access that will be used on this project
include:
• Stabilized Construction Entrance (BMP C105)
I
Stormwater Pollution Prevention Plan
Install the temporary construction entrance, according to the approved
construction plans, prior to any clearing or grading activities. Maintain until the
access road is paved.
Alternate construction access BMPs are included in Appendix C 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 C after the first sign that existing BMPs are ineffective or
failing.
3.1.3 Element 93 — Control Flow Rates
In order to protect the properties and waterways downstream of the project site, stormwater
discharges from the site will be controlled.
Flow control BMPs are included in Appendix C 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 C after the first sign that existing BMPs are ineffective or
failing.
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).
3.1.4 Element #4 — Install Sediment Controls
All stormwater runoff from disturbed areas shall pass through Wet vault#1 which will be used as
a sediment pond during construction. The specific BMPs to be used for controlling sediment on
this project also include:
• Silt Fence (BMP C233)
Install silt fencing, according to the approved plans, prior to any clearing or
grading activities. Maintain until all construction activities are completed.
• Storm Drain Inlet Protection (BMP C220)
6
Stormwater Pollution Prevention Plan
Install catch basin filters, according to the approved construction plans, as catch
basins are installed and become operable. Maintain until all construction
activities are completed.
Alternate sediment control BMPs are included in Appendix C 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 C 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 wash -off 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 bio-
filtration; 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 re -stabilized with vegetation per applicable design requirements once the remainder of
the site has been stabilized.
The following BMP 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.
• Temporary Sediment Pond (BMP C241)
Construct the temporary sediment pond, according to the approved construction
plans, prior to any grading activities. Maintain until site grading is completed and
the detention vault is operable
7
Stormwater Pollution Prevention Plan
3.1.5 Element #5 — Stabilize Soils
Exposed and un -worked soils shall be stabilized with the application of effective BMPs to
prevent erosion throughout the life of the project. The specific BMPs for soil stabilization that
shall be used on this project include:
• Temporary and Permanent Seeding (BMP C120)
Apply temporary hydro -seed to exposed and un -worked soils, according to the
approved construction plans, as needed to prevent erosion during site grading.
Apply permanent hydro -seed to areas at final grade as site grading is completed.
• Mulching (BMP C 12 1)
Apply mulching to exposed and un -worked soils, according to the approved
construction plans, as needed to prevent erosion during site grading. Maintain
until site grading is completed and permanent hydro -seed is applied.
• Plastic Covering (BMP C123)
Cover stockpiles with plastic sheeting, according to the approved construction
plans, as needed to prevent erosion during site grading. Maintain until stockpiles
are removed from site.
• Early application of gravel base on areas to be paved
Place gravel base on roadways, according to the approved construction plans,
after roadways are graded to sub -grade. Maintain until roads are paved.
Alternate soil stabilization BMPs are included in Appendix C 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 C after the first sign that existing BMPs are ineffective or
failing.
The project site is located west of the Cascade Mountain Crest. As such, no soils shall remain
exposed and unworked for more than 7 days during the dry season (May 1 to September 30) and
2 days during the wet season (October 1 to April 30). Regardless of the time of year, all soils
shall be stabilized at the end of the shift before a holiday or weekend if needed based on weather
forecasts.
Stormwater Pollution Prevention Plan
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.
3.1.6 Element #6 — Protect Slopes
All cut and fill slopes will be designed, constructed, and protected in a manner than minimizes
erosion. The following specific BMPs will be used to protect slopes for this project:
• Temporary and Permanent Seeding (BMP C120)
Apply temporary hydro -seed to cut and fill slopes, according to the approved
construction plans, as needed to minimize erosion during site grading. Apply
permanent hydro -seed to cut and fill slopes at final grade as site grading is
completed.
Alternate slope protection BMPs are included in Appendix C 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 C after the first sign that existing BMPs are ineffective or
failing.
3.1.7 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:
Drop Inlet Protection
• Catch Basin Filters
Install catch basin filters, according to the approved construction plans, as
catch basins become operable. Maintain until all construction activities are
completed.
9
Stormwater Pollution Prevention Plan
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 C.
3.1.8 Element #8 — Stabilize Channels and Outlets
Where site runoff is to be conveyed in channels, or discharged to a stream or some other natural
drainage point, efforts will be taken to prevent downstream erosion. The specific BMPs for
channel and outlet stabilization that shall be used on this project include:
• Outlet Protection (BMP C209)
Place rip -rap pad at the temporary sediment pond outfall, according to the
approved construction plans, before the pond becomes operable. Maintain until
the pond is removed or made in -operable.
Alternate channel and outlet stabilization BMPs are included in Appendix C 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 C after the first sign that existing BMPs are
ineffective or failing.
The project site is located west of the Cascade Mountain Crest. As such, all temporary on-site
conveyance channels shall be designed, constructed, and stabilized to prevent erosion from the
expected peak 10 minute velocity of flow from a Type 1A, 10 -year, 24-hour recurrence interval
storm for the developed condition. Alternatively, the 10 -year, 1 -hour peak flow rate indicated by
an approved continuous runoff simulation model, increased by a factor of 1.6, shall be used.
Stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent
stream banks, slopes, and downstream reaches shall be provided at the outlets of all conveyance
systems.
3.1.9 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.
10
Stormwater Pollution Prevention Plan
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.
Chemical storage:
■ Any chemicals stored in the construction areas will conform to the
appropriate source control BMPs listed in Volume IV of the Ecology
stormwater manual. In Western WA, all chemicals shall have cover,
containment, and protection provided on site, per BMP C153 for Material
Delivery, Storage and Containment in SWMMWW 2005
■ Application of agricultural chemicals, including fertilizers and pesticides,
shall be conducted in a manner and at application rates that will not result
in loss of chemical to stormwater runoff. Manufacturers'
recommendations for application procedures and rates shall be followed.
Excavation and tunneling spoils dewatering waste:
■ Dewatering BMPs and BMPs specific to the excavation and tunneling
(including handling of contaminated soils) are discussed under Element
10.
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).
11
Stormwater Pollution Prevention Plan
■ Process water and slurry resulting from saw -cutting and surfacing
operations will be prevented from entering the waters of the State by
implementing Saw -cutting and Surfacing Pollution Prevention measures
(BMP C 152).
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.
■ Wheel wash or tire bath wastewater shall be discharged to a separate on-
site treatment system or to the sanitary sewer as part of Wheel Wash
implementation (BMP C 106).
Solid Waste:
Other:
■ Solid waste will be stored in secure, clearly marked containers.
■ Other BMPs will be administered as necessary to address any additional
pollutant sources on site.
The facility is transportation -related and therefore not subject to the Federal requirements of the
Spill Prevention, Control, and Countermeasure (SPCC) Plan under the Clean Water Act (CWA).
If applicable, the Contractor shall prepare an SPCC Plan according to the Washington State
Department of Transportation (WSDOT) Requirements (see the WSDOT Standard
Specifications for Road, Bridge, and Municipal Construction 2004).
A SPCC plan is required for this site.
As per the Federal regulations of the Clean Water Act (CWA) and according to Final Rule 40
CFR Part 112, as stated in the National Register, a Spill Prevention, Control, and
Countermeasure (SPCC) Plan is required for construction activities. A SPCC Plan has been
prepared to address an approach to prevent, respond to, and report spills or releases to the
environment that could result from construction activities. This Plan must:
■ Be well thought out in accordance with good engineering;
12
Stormwater Pollution Prevention Plan
■ Achieve three objectives - prevent spills, contain a spill that occurs, and
clean up the spill;
■ Identify the name, location, owner, and type of facility;
■ Include the date of initial operation and oil spill history;
■ Name the designated person responsible;
■ Show evidence of approval and certification by the person in authority;
and
■ Contain a facility analysis.
3.1.10 Element #10 — Control Dewatering
No dewatering is anticipated for this project. If dewatering occurs, Baker tanks are proposed for
dewatering.
Alternate dewatering control BMPs are included in Appendix C 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 C after the first sign that existing BMPs are ineffective or
failing.
3.1.11 Element #11— Maintain BMPs
All temporary and permanent erosion and sediment control BMPs shall be maintained and
repaired as needed to assure continued performance of their intended function. Maintenance and
repair shall be conducted in accordance with each particular BMP's specifications. Visual
monitoring of the BMPs will be conducted at least once every calendar week and within 24 hours
of any rainfall event that causes a discharge from the site. If the site becomes inactive, and is
temporarily stabilized, the inspection frequency will be reduced to once every month.
All temporary erosion and sediment control BMPs shall be removed within 30 days after the
final site stabilization is achieved or after the temporary BMPs are no longer needed. Trapped
sediment shall be removed or stabilized on site. Disturbed soil resulting from removal of BMPs
or vegetation shall be permanently stabilized.
13
Stormwater Pollution Prevention Plan
3.1.12 Element #12 — Manage the Project
Erosion and sediment control BMPs for this project have been designed based on the following
principles:
■ 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.
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.
■ Re -vegetation 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:
❑ Site conditions including existing vegetative coverage, slope, soil
type, and proximity to receiving waters; and
❑ Limitations on activities and the extent of disturbed areas; and
14
Stormwater Pollution Prevention Plan
❑ 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:
❑ Routine maintenance and necessary repair of erosion and sediment
control BMPs;
❑ 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
❑ Activities where there is 100 percent infiltration of surface water
runoff within the site in approved and installed erosion and
sediment control facilities.
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:
❑ Assess the site conditions and construction activities that could
impact the quality of stormwater, and
❑ 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
15
Stormwater Pollution Prevention Plan
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.
3.2 Site Specific BMPs
Site specific BMPs are shown on the TESC Plan Sheets and Details in Appendix A. These site
specific plan sheets will be updated annually.
3.3 Additional Advanced BMPs
16
Stormwater Pollution Prevention Plan
4.0 Construction Phasing and BMP
Implementation
The BMP implementation schedule will be driven by the construction schedule. The following
provides a sequential list of the proposed construction schedule milestones and the corresponding
BMP implementation schedule. The list contains key milestones such as wet season
construction.
The BMP implementation schedule listed below is keyed to proposed phases of the construction
project, and reflects differences in BMP installations and inspections that relate to wet season
construction. The project site is located west of the Cascade Mountain Crest. As such, the dry
season is considered to be from May 1 to September 30 and the wet season is considered to be
from October 1 to April 30.
• Estimate of Construction start date:
May 1, 2013
• Estimate of Construction finish date:
December 30, 2013
Site inspections and monitoring conducted weekly and for
applicable rain events as detailed in Section 6 of this
SWPPP. Implement Element #12 BMPs and manage site
to minimize soil disturbance during the wet season.
• Dry Season begins:
May 1, 2013
• Mobilize equipment on site
May 1, 2013
• Mobilize and store all ESC and soil stabilization products
May 1, 2013
• Install ESC measures:
May 1, 2013
• Install stabilized construction entrance:
May 1, 2013
• Begin clearing and grubbing:
June 15,2013
• Site grading begins:
June 25,2013
• Grade road and stabilize with gravel base
June 25,2013
• Begin excavation for new utilities and services
July 10,2013
• Soil stabilization on excavated side slopes (in idle, no work
areas)
July 25, 2013
• Dry Season begins:
May 1, 2013
• Temporary erosion control measures (hydro -seeding)
May 1, 2013
• Site grading ends:
July 10, 2013
• Wet Season Begins:
Oct 1, 2013
• Begin pouring concrete curbs & sidewalks and implement
BMP C151:
July 25, 2013
• Pave asphalt roads
August 5, 2013
17
Stormwater Pollution Prevention Plan
• Wet Season started: Oct 1, 2013
• Implement Element #12 BMPs and manage site to minimize
soil disturbance during the wet season: Oct 1, 2013
• Final landscaping and planting begins: November 10,2013
• Permanent erosion control measures (hydro -seeding): November 25, 2013
18
Stormwater Pollution Prevention Plan
5.0 Pollution Prevention Team
5.1 Roles and Responsibilities
The pollution prevention team consists of personnel responsible for implementation of the
SVWPPP, including the following:
■ Certified Erosion and Sediment Control Lead (CESCL) — primary
contractor contact, responsible for site inspections (BMPs, visual
monitoring, sampling, etc.); to be called upon in case of failure of any
ESC measures.
■ Resident Engineer — For projects with engineered structures only
(sediment ponds/traps, sand filters, etc.): site representative for the owner
that is the project's supervising engineer responsible for inspections and
issuing instructions and drawings to the contractor's site supervisor or
representative.
■ Emergency Ecology Contact — individual to be contacted at Ecology in
case of emergency.
■ Emergency Owner Contact — individual that is the site owner or
representative of the site owner to be contacted in the case of an
emergency.
■ Non -Emergency Ecology Contact — individual that is the site owner or
representative of the site owner than can be contacted if required.
■ Monitoring Personnel — personnel responsible for conducting water
quality monitoring; for most sites this person is also the Certified Erosion
and Sediment Control Lead.
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Stormwater Pollution Prevention Plan
5.2 Team Members
Names and contact information for those identified as members of the pollution prevention team
are provided in the following table.
Title
Name(s)
Phone Number
Certified Erosion and Sediment Control Lead (CESCL)
TBD
xxx-xxx-xxxx
Resident Engineer
Brian Kalab / Insight Engineering
425-303-9363
Emergency Ecology Contact
Tracy Walters
425-649-7000
Emergency Owner Contact
Fazel Kassam
505-243-6000
Non -Emergency Ecology Contact
Tracy Walters
425-649-7000
Monitoring Personnel
TBD
xxx-xxx-xxxx
20
Stormwater Pollution Prevention Plan
6.0 Site Inspections and Monitoring
Monitoring includes visual inspection, monitoring for water quality parameters of concern, and
documentation of the inspection and monitoring 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; and,
■ Stormwater quality monitoring.
For convenience, the inspection form and water quality monitoring forms included in this
SWPPP include the required information for the site log book. This SWPPP may function as the
site log book if desired, or the forms may be separated and included in a separate site log book.
However, if separated, the site log book but must be maintained on-site or within reasonable
access to the site and be made available upon request to Ecology or the local jurisdiction.
6.1 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 5 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.
6.1.1 Site Inspection Frequency
Site inspections will be conducted at least once a week and within 24 hours following any
rainfall event which causes a discharge of stormwater from the site. For sites with temporary
stabilization measures, the site inspection frequency can be reduced to once every month.
21
Stormwater Pollution Prevention Plan
6.1.2 Site Inspection Documentation
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.
6.2 Stormwater Quality Monitoring
6.2.1 Turbidity Sampling
Monitoring requirements for the proposed project will include either turbidity or water
transparency sampling to monitor site discharges for water quality compliance with the 2005
Construction Stormwater General Permit (Appendix D). Sampling will be conducted at all
discharge points at least once per calendar week.
Turbidity or transparency monitoring will follow the analytical methodologies described in
Section S4 of the 2005 Construction Stormwater General Permit (Appendix D). The key
benchmark values that require action are 25 NTU for turbidity (equivalent to 32 cm
transparency) and 250 NTU for turbidity (equivalent to 6 cm transparency). If the 25 NTU
benchmark for turbidity (equivalent to 32 cm transparency) is exceeded, the following steps will
be conducted:
1. Ensure all BMPs specified in this SWPPP are installed and functioning as
intended.
2. Assess whether additional BMPs should be implemented, and document
revisions to the SWPPP as necessary.
3. Sample discharge location daily until the analysis results are less than 25
NTU (turbidity) or greater than 32 cm (transparency).
If the turbidity is greater than 25 NTU (or transparency is less than 32 cm) but less than 250
NTU (transparency greater than 6 cm) for more than 3 days, additional treatment BMPs will be
implemented within 24 hours of the third consecutive sample that exceeded the benchmark
value. Additional treatment BMPs to be considered will include, but are not limited to, off-site
treatment, infiltration, filtration and chemical treatment.
If the 250 NTU benchmark for turbidity (or less than 6 cm transparency) is exceeded at any time,
the following steps will be conducted:
1. Notify Ecology by phone within 24 hours of analysis (see Section 5.0 of
this SWPPP for contact information).
22
Stormwater Pollution Prevention Plan
2. Continue daily sampling until the turbidity is less than 25 NTU (or
transparency is greater than 32 cm).
3. Initiate additional treatment BMPs such as off-site treatment, infiltration,
filtration and chemical treatment within 24 hours of the first 250 NTU
exceedance.
4. Implement additional treatment BMPs as soon as possible, but within 7
days of the first 250 NTU exceedance.
5. Describe inspection results and remedial actions taken in the site log book
and in monthly discharge monitoring reports as described in Section 7.0 of
this SWPPP.
6.2.2 pH Sampling
Stormwater runoff will be monitored for pH starting on the first day of any activity that includes
more than 40 yards of poured or recycled concrete, or after the application of "Engineered Soils"
such as, Portland cement treated base, cement kiln dust, or fly ash. This does not include
fertilizers. For concrete work, pH monitoring will start the first day concrete is poured and
continue until 3 weeks after the last pour. For engineered soils, the pH monitoring period begins
when engineered soils are first exposed to precipitation and continue until the area is fully
stabilized.
Stormwater samples will be collected daily from all points of discharge from the site and
measured for pH using a calibrated pH meter, pH test kit, or wide range pH indicator paper. If
the measured pH is 8.5 or greater, the following steps will be conducted:
1. Prevent the high pH water from entering storm drains or surface water.
2. Adjust or neutralize the high pH water if necessary using appropriate
technology such as CO2 sparging (liquid or dry ice).
3. Contact Ecology if chemical treatment other than CO2 sparging is planned.
23
Stormwater Pollution Prevention Plan
7.0 Reporting and Recordkeeping
7.1 Recordkeeping
7.1.1 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; and,
■ Stormwater quality monitoring.
For convenience, the inspection form and water quality monitoring forms included in this
SWPPP include the required information for the site log book.
7.1.2 Records Retention
Records of all monitoring information (site log book, inspection reports/checklists, etc.),
this Stormwater Pollution Prevention Plan, and any other documentation of compliance
with permit requirements will be retained during the life of the construction project and
for a minimum of three years following the termination of permit coverage in accordance
with permit condition S5.C.
7.1.3 Access to Plans and Records
The SWPPP, General Permit, Notice of Authorization letter, and Site Log Book will be
retained on site or within reasonable access to the site and will be made immediately
available upon request to Ecology or the local jurisdiction. A copy of this SWPPP will
be provided to Ecology within 14 days of receipt of a written request for the SWPPP
from Ecology. Any other information requested by Ecology will be submitted within a
reasonable time. A copy of the SWPPP or access to the SWPPP will be provided to the
public when requested in writing in accordance with permit condition S5.G.
7.1.4 Updating the SWPPP
In accordance with Conditions S3, S4.13, and S9.13.3 of the General Permit, this SWPPP
will be modified if the SWPPP is ineffective in eliminating or significantly minimizing
24
Stormwater Pollution Prevention Plan
pollutants in stormwater discharges from the site or there has been a change in design,
construction, operation, or maintenance at the site that has a significant effect on the
discharge, or potential for discharge, of pollutants to the waters of the State. The SWPPP
will be modified within seven days of determination based on inspection(s) that
additional or modified BMPs are necessary to correct problems identified, and an updated
timeline for BMP implementation will be prepared.
7.2 Reporting
7.2.1 Discharge Monitoring Reports
Water quality sampling results will be submitted to Ecology monthly on Discharge
Monitoring Report (DMR) forms in accordance with permit condition S5.13. If there was
no discharge during a given monitoring period, the form will be submitted with the words
"no discharge" entered in place of the monitoring results. If a benchmark was exceeded,
a brief summary of inspection results and remedial actions taken will be included. If
sampling could not be performed during a monitoring period, a DMR will be submitted
with an explanation of why sampling could not be performed.
7.2.2 Notification of Noncompliance
If any of the terms and conditions of the permit are not met, and it causes a threat to
human health or the environment, the following steps will be taken in accordance with
permit section S5.17:
Ecology will be immediately notified of the failure to comply.
2. Immediate action will be taken to control the noncompliance issue
and to correct the problem. 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.
In accordance with permit condition S4.F.6.b, the Ecology regional office will be notified
if chemical treatment other than CO2 sparging is planned for adjustment of high pH water
(see Section 5.0 of this SWPPP for contact information).
25
Stormwater Pollution Prevention Plan
7.2.3 Permit Application and Changes
In accordance with permit condition S2.A, a complete application form will be submitted
to Ecology and the appropriate local jurisdiction (if applicable) to be covered by the
General Permit.
Appendix A — Site Plans
Appendix B — Construction BMPs
Element #1 - Mark Clearing Limits
High Visibility Plastic or Metal Fence (BMP C103)
Element #2 - Establish Construction Access
Stabilized Construction Entrance (BMP C105)
Element #3 - Control Flow Rates
Detention Vault
Element #4 - Install Sediment Controls
Silt Fence (BMP C233)
Storm Drain Inlet Protection (BMP C220)
Interceptor Dike and Swale (BMP C200)
Element #5 - Stabilize Soils
Mulching (BMP C121)
Temporary and Permanent Seeding (BMP C120)
Element #6 - Protect Slopes
Plastic Covering (BMP C123)
Element #8 - Stabilize Channels and Outlets
Outlet Protection (BMP C209)
26
Element #10 - Control Dewatering
Additional Advanced BMPs to Control Dewatering:
Element #11— Maintain BMP's
Scheduling (BMP C162)
Element #12 — Manage the Project
CESC Lead (BMP C160)
27
Stormwater Pollution Prevention Plan
Stormwater Pollution Prevention Plan
Appendix C — Alternative BMPs
The following includes a list of possible alternative BMPs for each of the 12 elements not
described in the main SWPPP text. This list can be referenced in the event a BMP for a
specific element is not functioning as designed and an alternative BMP needs to be
implemented.
Element 91 - Mark Clearing Limits
Preserving Natural Vegetation (C 10 1)
Element #2 - Establish Construction Access
Wheel Wash (C 106)
Construction Road/Parking area stabilization (BMP C 107)
Element #3 - Control Flow Rates
Temporary Sediment Pond (BMP C241)
Sediment Trap (BMP C240)
Element #4 - Install Sediment Controls
Triangular Silt Dike (BMP C208)
Element #5 - Stabilize Soils
Surface roughening (BMP C130)
Element #6 - Protect Slopes
Nets and Blankets (BMP C 122)
Element #8 - Stabilize Channels and Outlets
Channel Lining (BMP C202)
Element #10 - Control Dewatering
Element #11 — Maintain BMP's
Element #12 — Manage the Project
28
Appendix D — General Permit
I
Stormwater Pollution Prevention Plan
Stormwater Pollution Prevention Plan
Appendix E — Site Inspection Forms (and Site Log)
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:
a. Inspection date/times
b. Weather information: general conditions during inspection,
approximate amount of precipitation since the last inspection,
and approximate amount of precipitation within the last 24 hours.
C. A summary or list of all BMPs that have been implemented,
including observations of all erosion/sediment control structures or
practices.
d. The following shall be noted:
i. locations of BMPs inspected,
ii. locations of BMPs that need maintenance,
iii. the reason maintenance is needed,
iv. locations of BMPs that failed to operate as designed or
intended, and
V. locations where additional or different BMPs are needed, and
the reason(s) why
e. 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.
f. A description of any water quality monitoring performed during
inspection, and the results of that monitoring.
g. General comments and notes, including a brief description of any
BMP repairs, maintenance or installations made as a result of the
inspection.
30
Stormwater Pollution Prevention Plan
h. 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.
i. 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 S5.17 of the permit.
31
Stormwater Pollution Prevention Plan
Appendix F — Engineering Calculations
See Stormwater Site Plan dated December 6, 2013
32
8.0 Appendix
A. Kennydale Cafe TIR
B. "The Bluffs" Phase 1 and 2 TIR
C. Sensitive Areas Map
Insight Engineering Co. - Stormwater Site Plan
-19-
12/19/14
i
i
i
Kennydale Cafe
1322 Lake Washington Boulevard
SURFACE WATER
TECHNICAL INFORMATION REPORT
March 16, 2006
01
i`•� ti
EXPIRES 08/08 .0"
Prepared by:
LPD Engineering, PLLC
7936 Seward Park Avenue South,
Suite 100
Seattle,WA 98118
Contact: Steve Hatzenbeler, P.E.
(206) 725-1211
Prepared for:
Pool Brothers Construction
PO Box 3023
Renton, WA 98056
Contact: Matt Pool CITYOFRsNTON
(253) 405-3475 g F C F 1 VF P
MAR 2 9 2097
BUQD1NGD1V1S10R'
2�;1'3wo
Kennydale Cafe
1322 Lake Washington Boulevard
Surface Water Technical Information Report
Table of Contents
SECTION I: PROJECT OVERVIEW......................................................:.................1
SECTION II: PRELIMINARY CONDITIONS SUMMARY........................................2
SECTION III: OFF-SITE ANALYSIS........................................................................ 3
SECTION IV: RETENTION/DETENTION ANALYSIS AND DESIGN .....................4
SECTION V: CONVEYANCE SYSTEM ANALYSIS AND DESIGN........................5
SECTION VI: SPECIAL REPORTS AND STUDIES...............................................5
SECTION VII: BASIN AND COMMUNITY PLAN AREAS......................................6
SECTION VIII: OTHER PERMITS...........................................................................6
SECTION IX: EROSION/SEDIMENTATION CONTROL DESIGN .........................6
SECTION X: BOND QUANTITIES WORKSHEET, RETENTION/DETENTION
FACILITY SUMMARY SHEET, AND DECLARATION OF COVENANT.................7
SECTION XI: MAINTENANCE AND OPERATIONS MANUAL ..............................7
FIGURES
Figure 1 TIR Worksheet
Figure 2 Vicinity Map
Figure 3 (a, b) Soils Map and Legend
Figure 4a Off Site Analysis Drainage System Table
Figure 4b Off Site Downstream Drainage Map
APPENDICES
Appendix A - Preliminary Design Documents
Appendix B - Design Calculations
Appendix C - Supporting Information
CITYOFRcNTON
R ECF! a1Fr')
MAR 2 9 2007
F31NDINGDIUISI(7r
KING COUNTY
SURFACE WATERTECHNICAL INFORMATION REPORT
Kennydale Cafe - 1322 Lake Washington Boulevard
Section I: Project Overview
This Technical Information Report is for the Kennydale Cafd project located at 1322 Lake Washington Blvd N
in Renton, Washington. The TIR addresses the seven core and twelve special requirements of the 1990 King
County Surface Water Design Manual (KCSWDM). A Level 1 downstream analysis is also included. Note that
this report updates the preliminary TIR submitted in January 2006.
The proposed development is the construction of a 3 -story mixed use building with associated parking and
public open space. Given the topography of the existing site, a number of structural retaining walls will be
included in the proposed design. To minimize the impact on the steeper portion of the site to the east,
proposed improvements are located as far to the west of the property as is feasible. The building has been sited
fronting the street as encouraged by land use to facilitate pedestrian access and enhance the aesthetic of the
street.
I Existing site
The existing site slopes up from a low point along Lake Washington Blvd westerly towards the Interstate 405
right of way. The slopes vary from 15% up to 40% and greater (Please note that a protected slope exemption
has been granted for this project). The site is in an Aquifer Protection Zone 2.
The existing site is currently undeveloped; a building that was previously located on the site has been
demolished, and the foundation remains. The site is vegetated with some mature'12 to 18 -inch trees and an
under story of blackberry and other invasive vegetation. The site soils are brown, silty sand overlying dense silt
and fine sand. The site soils investigation determined that the upper 3 to 8 feet of soil is relatively loose while
the deeper soils are dense and characterized as highly moisture sensitive. According to the King County Soil
Survey maps the site soils are Alderwood and Kitsap soils (AkF) (See Figure 3a & 3b — Soils Map).
Based on the surveyed topography and site observations, the existing site appears to drain via surface runoff
from east to west across Lake Washington Blvd, with runoff from some of the area being directed to a catch
basin on private property northwest of the site, on the same side of the street. The roadway is super -elevated
fronting the site and there is no ditch or drainage collection system along the east side of the road, so runoff
leaving the site sheet flows across.
Proposed site
The proposed development will construct approximately'12,000 square feet (sf) of impervious area subject to
vehicular use. Parking lot runoff will be collected in catch basins and routed through a water quality treatment
wetvault. Discharge from the water quality facility will join the tightlined drainage from the building
downspouts and be routed to an existing storm drain manhole located in the unimproved Morgan Ave. (SE
110th St) right of way just north of the property (refer to permit documents in Appendix A).
Stormwater Improvements
Per the City of Renton, the project is subject to the requirements of the 1990 King County Surface Water
Design Manual with City of Renton Amendments. The project is located within an Aquifer Protection Zone 2.
Based on these requirements, the project will provide basic water quality treatment for runoff from impervious
KING COUNTY TIR Page I Kennydale Cafe
LPD Engineering, PLLC March 16, 2007
areas subject to vehicular use. The project will create a negligible increase in the peak runoff rate so detention
is not required. Refer to Section II and Section IV below for additional information.
Section II: Preliminary Conditions Summary
This section addresses the requirements set forth by the 1990 KCSWDM, Core and Special Requirements
listed in Chapter 1.
1. Discharge at the Natural Location (1.2.1): All flows from this project site will remain in the natural
drainage patterns within a quarter mile downstream of the project. See the off site investigation included
in Section III of this report.
2. Off -Site Analysis (1.2.2): An off site analysis was performed for this project and is included in Section III
of this report.
3. Runoff Control (1.2.3): The project is within the Lake Washington E drainage sub basin and is not subject
to special runoff volume controls. The estimate of the peak runoff rate from the proposed project site 100 -
year, 24-hour duration design storm event is calculated to be less than a 0.5 cfs increase above the peak
runoff rate for the existing site 100 -year, 24-hour duration storm event; therefore, the project is exempt
from on-site runoff control based on the Negligible Peak Runoff Rate Increase exemption defined in Core
Requirement #3.
The estimated peak runoff rates for the 100 -year, 24-hour duration storm events are as follows:
Existing 100 -year peak = 0.38 cfs
Post -Developed 100 -year peak = 0.46 cfs
Net change in 100 -year peak rate = 0.08 cfs
The proposed project will result in surface water runoff from more than five thousand (5,000) square feet
of impervious surface subject to vehicular use. Per COR code 4-6-030 E.3.b, this impervious runoff shall
be treated prior to discharge with biofiltration measures. A biofiltration swale design was evaluated, but
we are requesting that the City of Renton consider a water quality wetvault as an equivalent method of
treatment. See Section IV of this report for additional information and justification.
4. Conveyance System (1.2.4): The project includes a tight line conveyance system in the proposed parking
lots that will collect onsite drainage from the proposed impervious surfaces subject to vehicular use and
route it through the stormwater treatment facilities. A separate storm drainage conveyance system will be
installed to bypass flows from non -vehicular areas around the water quality facility. Per City of Renton
Code 4-6-030 E.3.g, any open channel may require a liner to prevent groundwater contamination;
however, no open channels are proposed as part of this project. Refer to Section V of this report.
5. Erosion/Sedimentation Control Plan (1.2.5): A full TESC plan is included with this submittal and is
designed in accordance with the 1990 KCSWDM requirements. This plan will be considered the minimum
for anticipated site conditions. The Contractor will be responsible for implementing all TESC measures
and upgrading them as necessary. The TESC facilities will be installed prior to any clearing, grubbing or
construction.
6. Maintenance and Operation (1.2.6): A copy of the KCSWDM recommended maintenance guidelines for
catch basins and conveyance systems is included in Appendix B.
7. Bonds and Liability (1.2.7): This Core requirement is specifically required for projects constructed and
permitted in King County and is not applicable for the City of Renton. City of Renton requires bonding for
all improvements in the public right of way. The Owner will post a bond equal to 100% of the estimated
KING COUNTY TIR Page 2 Kennydale Cafe
LPD Engineering, PLLC March 16, 2007
value of improvements in the public right of way, prior to construction. An engineer's estimate of probable
cost will be included with the permit application.
Special Requirements
1. Critical Drainage Areas — Project is not within a designated critical drainage area.
2. Compliance with an Existing Master Drainage Plan — Project is not within an area covered by an
approved Master Drainage Plan.
3. Conditions Requiring a Master Drainage Plan — Project is not a Master Planned Development or a
subdivision or Planned Unit Development that will have more than 100 lots. It is not a commercial
development or Planned Unit Development that will construct more than 50 acres of impervious
surface. And the project will not clear more than 500 acres within a contiguous drainage sub -basin.
Therefore, a Master Drainage Plan is not required.
4. Adopted Basin or Community Plans —Project is not within an area with an adopted plan.
5. Special Water Quality Controls — The project proposes discharge to a conveyance system that
eventually outfalls to Johns Creek in Gene Coulon Beach Park and discharges to Lake Washington.
See Section III for the Off -Site Analysis. Water quality treatment for impervious areas subject to
vehicular use will be required as indicated by City of Renton codified amendments to the KCSWDM
as noted above.
6. Coalescing Plate Oil/Water Separators — The project will not construct more than 5.acres of
impervious surface.
7. Closed Depressions — The proposed project will not discharge runoff to an existing closed depression.
8. Use of Lakes, Wetlands, or Closed Depressions for Peak Rate Runoff Control —The project will not
use a lake, wetland, or closed depression for peak rate runoff control.
9. Delineation of 100 Year Floodplain — The proposed project site does not contain or abut a stream,
lake, wetland or closed depression.
10. Flood Protection Facilities for Type 1 and 2 Streams — The proposed project does not contain or abut
a Class 1 or 2 stream that has a flood protection facility.
11. Geotechnical Analysis and Report — A geotechnical analysis should not be required for the
construction of the stormwater facilities, however a geotechnical study has been performed and
consideration has been given to the geotechnical recommendations regarding site, wall, and
foundation drainage. A copy of the geotechnical study is attached in Appendix C.
12. Soils Analysis And Report — The soils analysis is included in the geotechnical report noted above.
Section III: Off -Site Analysis
The following is the preliminary Level 1 downstream analysis. This downstream analysis is based upon the
following:
• LPD Engineering, PLLC site investigation January 17, 2006 — The site was visited on a partly
sunny day which followed a period of nearly 30 consecutive days of record amounts of rainfall.
• Meeting with Arneta Henninger, City of Renton Engineering Specialist, 10/26/05 and 11/23/04.
• Review of City of Renton as -built records including Pinnacle at the Bluffs Grading and Drainage,
as built drawings (1/30/02).
• Review of project topographic survey by Sadler/Barnard.
KING COUNTY TIR Page 3 Kennydale Cafe
LPD Engineering, PLLC March 16, 2007
Existing condition
The subject property is currently undeveloped. There is an existing abandoned building foundation on the site.
The site is vegetated with what appears to be second growth with an under story of blackberry and other
invasive vegetation.
The site is bounded to the east by Interstate Highway 405 right of way, to the north by unimproved SE 110th St
(Morgan St) right of way, on the west by Lake Washington Blvd right of way, and on the south by a privately
owned parcel that is currently being used for vehicle storage and an espresso stand.
The existing site slopes up from a low point along Lake Washington Blvd easterly towards the I-405 right of
way. The slopes vary from 15% up to 40% and greater (note that a protected slope exemption has been granted
for this project). The site is in an area designated by the City of Renton as Aquifer Protection Zone 2.
Developed condition
The proposed discharge point for runoff from the site is an existing storm drainage manhole located in the
unimproved Morgan St right of way immediately north of the proposed development, and just east of the Lake
Washington Blvd right of way.
The path of drainage from the site is described as follows (see Figure 4a — Off Site Analysis Drainage System
Table, and Figure 4b — Off -Site Drainage Map):
• From the existing storm drain manhole the flow is conveyed west across the Lake Washington
Blvd right of way in an 18 -inch diameter PVC pipe, a distance of approximately 70 LF. .
• The 18 -inch pipe outfalls west of the Lake Washington Blvd right of way to an open channel that
conveys the flow south, parallel to the road and the railroad tracks. The channel is armored with 4
to 6 -inch quarry spalls, and is approximately 2 to 3 feet wide and 18 inches deep, with 3(H):l(V)
side slopes. The channel is approximately 120 feet long.
• The channel flows into a 24 -inch CMP culvert which conveys the water to the west under the
railroad tracks, through a catchbasin, into another 24 -inch CMP pipe, and to an outfall at Johns
Creek in Gene Coulon Beach Park.
• Johns Creek is a stream reach that flows through Gene Coulon Beach Park and discharges into
Lake Washington.
Existing and Predicted Problems
The downstream conveyance system within '/a mile of the proposed development property is in good condition
with no indications of drainage problems observed and none predicted.
Section IV: Retention/Detention Analysis and Design
Preliminary drainage drawings are included in Appendix A.
Detention
As noted in the core requirements section of this report, the project qualifies for the Negligible Peak Runoff
Rate Increase exemption and detention is not required for the project. See the attached preliminary drainage
calculations in Appendix B.
Water Quality Treatment
As noted in the core requirements section of this report, water quality treatment is required to treat the runoff
from the impervious areas subject to vehicular use. LPD Engineering wrote a letter to the City of Renton
(10/27/05) requesting a drainage requirement adjustment to allow an alternative method of treatment. A copy
of the letter is attached in Appendix C and a summary of the key issues is included below.
In coordination with City planners, the Owner and Architect have arrived at a preliminary design that sites the
building near Lake Washington Blvd. The building location was chosen to minimize the impact to the steep
KING COUNTY TIR Page 4 Kennydale Cafe
LPD Engineering, PLLC March 16, 2007
slopes on the eastern portion of the site, to facilitate pedestrian access and enhance the aesthetic of the street.
The Architect is proposing a landscaped plaza area with outdoor seating and multiple access points to the
sidewalk along Lake Washington Blvd. .
The most feasible location for a biofiltration swale is in the space proposed for the plaza area. Siting the swale
here would create restrictions and possibly safety issues for pedestrians in an area that is meant to encourage
pedestrian activity. A preliminary biofiltration swale design was performed to verify that if required, a swale
couldbe constructed in front of the building.
We have requested that an adjustment to the drainage code be granted to allow an underground water quality
treatment facility in lieu of a biofiltration swale on this site. Options include a wet vault or the Stormwater
Management, Inc.'s-Stomifilter treatment system.
Our understanding is that the City of Renton does not allow Stormfater systems, but they will allow use of a
wetvault for water quality treatment of runoff from impervious surfaces subject to vehicular traffic. The design
includes a wetvault for basic water -quality treatment. The proposed wetvault-is 5 feet wide and 26 feet long,
divided into 3 cells. The design includes a flow -splitter upstream of the wetvault to bypass flows greater than
the water quality design storm Wetvault sizing calculations are included in Appendix B.
Section V: Conveyance System Analysis and Design
On site, the drainage system is primarily comprised of 6 -inch pipes at slopes steeper than 2%, which convey
limited portions of the runoff from the various small sub -basins within the site. The exception is the 8 -inch
storm drain line along the west edge of the site, which conveys all flows from the project. The slope of the 8 -
inch line from the flow -splitter to the storm drain manhole off the northwest comer of the site is 0.6%, thus it is
the limiting factor on the capacity of the on-site system The maximum capacity of the 8 -inch line at 0.6% is
1.21 cfs. Estimates of peak runoff rate from the site showed that the peak runoff rate for the 100 -year, 24-hour
storm event is 0.46 cfs, so the 8 -inch storm drain line appears to provide excess capacity.
As noted above in the off site analysis above, the downstream drainage system begins in an 18 -inch pipe
heading to the west from the existing storm drain manhole near the northwest comer of the site. For the purpose
of analyzing the capacity of the downstream system we looked at the theoretical maximum capacity of -the 18-
inch storm drain line, which appears to be the most limited component of the downstream system. We do not
have the information necessary to be able to analyze all flows into the existing storm drain manhole because of
the contributions from so many different areas, so an analysis of peak runoff rates tributary to the 18 -inch pipe
has not been done. As. an alternative, we have analyzed the contribution of the proposed Kennydale C66 site
' development relative to the theoretical maximum capacity of the 18 -inch storm drain line.
Using a conservative slope estimate of 2.0%, we calculated a theoretical maxi num capacity of approximately
16.0 cubic feet per second (CFS) in the 18 -inch storm drain line. In the storm drainage analysis done for the
development's TR we determined that the peak runoff rate for the 100 -year, 24-hour storm on the proposed
site is approximately 0.46 .CFS, which is approximately 2.9% of the pipe's maximum capacity. The peak runoff
rate for the 100 -year, ' 24-hour storm on the existing site is approximately 0.38 CFS, which is approximately
2.4% of the theoretical maximum capacity of the pipe. Therefore, the developed conditions result in an increase
in peak runoff rate that is approximately 0.5% of the pipe's maximum capacity. Since there are no known
capacity issues that we have been made aware of in the downstream system, we assume that the nominal
' increase in peak runoff rate from our site will not present any concerns for the City of Renton. .
Section VI: Special Reports and Studies
With the exception of the Geotechnical Engineering Report, no special reports or studies are required for this
project.
KING COUNTY TIR Page 5 Kennydale Cafe.
LPD Engineering, PLLC March 16, 2007
Section VII: Basin and Community Plan Areas
The proposed development does not lie within an adopted Basin or Community Plan area.
Section VIII: Other Permits
No additional permits will be required for this project.
Section IX: Erosion/Sedimentation Control Design
Project plans include a Preliminary Temporary Erosion and Sedimentation Control (TESL) design (See
Preliminary Design Documents Appendix A), which includes the following TESC measures to be utilized:
• Construction Access Pads
• Perimeter Siltation Control Measures
• Temporary Interceptor Swales
• Temporary Sediment Pond —Sediment Pond sizing calculations are included in Appendix B.
The implementation of the TESC plan and construction maintenance, replacement and upgrading of the TESC
facilities shall bethe responsibility of the contractor per the contract documents. The TESL facilities will be
constructed prior to and in conjunction with all clearing and grading activity and is a manner which sediment or
sediment laden water does not leave the project site, enter the drainage system or violate applicable water
standards. The TESC measures shown on the plan are considered the minimum requirements for anticipated
conditions. During construction the contractor shall be responsible for upgrading these facilities as necessary.
As per Section 2.3.1 of the KCSWDM, the 11 minimum requirements of Core Requirement #5 must be
addressed. The following list explains how each minimum requirement is addressed:
Clearing Limits: Clearing Limits are identified on the TESC plan.
1. Cover Measures: Notes on the TESC plans have been included to address all relevant items. .
2. Perimeter Protection: Perimeter sedimentation control is shown on the TESC plans where necessary.
3. Traffic Area Stabilization: A stabilized construction access is shown on the TESC plans.
4. Sediment Retention: A temporary sediment pond is shown on the drawings.
5. Surface Water Control: Temporary interceptor swales for directing stormwater runoff to the sediment
pond are shown on the plans.
6. Dust Control: The TESC notes include requirements for dust control.
7. Wet Season Construction: Wet season special provisions are addressed in the TESC notes.
8. Construction within Sensitive Areas and Buffers: The project is not within a sensitive area or buffer.
Maintenance: TESC maintenance is addressed in the TESC notes.
10. Final Stabilization: Stabilization of the site, removal of TESC facilities; and cleaning of the drainage
system are addressed in the Construction Sequence on the TESC plans.
KING COUNTY TIR Page 6 Kennydale Cafe
LPD Engineering, PLLC March 16, 2007
Section X: Bond Quantities Worksheet, Retention/Detention
Facility Summary .Sheet, and Declaration of Covenant
The City of Renton has its own bonding requirements that do not require the Bond Quantity Worksheet. The
Retention/Detention Facility Summary Sheet and the Declaration of Covenant do not apply for this site because
there is no retention/detention system proposed.
Section Xl: Maintenance and Operations Manual
A copy of the KCSWDM recommended maintenance guidelines for catch basins and conveyance systems is
included in Appendix B.
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KING COUNTY TIR Page 7 Kennydale Cafe
LPD Engineering, PLLC March 16, 2007
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SECTION 4
Detention and Water Quality
Analysis and Design
Preliminary drainage drawings are included in Appendix A.
Detention
As noted in the core requirements section of this report, the project is subject to the negligible increase in peak
rate runoff exemption and detention is not required for the project. See the attached preliminary drainage
calculations.
Water Quality Treatment
As noted in the core requirements section of this report, water quality treatment is required to treat the runoff
from the impervious areas subject to vehicular use. LPD Engineering wrote a letter to the City of Renton
(10/27/06) requesting a drainage requirement adjustment to allow an alternative method of treatment. A copy
of the letter is attached and a summary of the key issues is included below.
In coordination with City planners the Owner and Architect have arrived at a preliminary design that sites the
building near Lake Washington Blvd. The building location was chosen to minimize the impact to the steep
slopes on the eastern portion of the site and to facilitate pedestrian access and enhance the aesthetic of the
street. The Architect is proposing a landscaped plaza area with outdoor seating multiple access points to the
sidewalk along Lake Washington Blvd.
The most feasible location for a biofiltration swale is in the space proposed for the plaza area. Siting the swale
here would create restrictions and possibly safety issues for pedestrians in area that intends to encourage
pedestrian activity. A preliminary biofiltration Swale design was performed to verify that if required, a swale
could be constructed in front of the building.
We request an adjustment of the drainage be granted to allow an underground water quality treatment facility in
lieu of a biofiltration swale on this site. Options include a wet vault or the Stormwater Management, Inc.'s
Stormfilter treatment system.
Our preferred method is the Stomifilter treatment system based on its performance and long term maintenance
advantages. Washington State Department of Ecology has approved use of the proposed Stormfilter Treatment
System as a basic stormwater treatment practice for total suspended solids (TSS) removal and King County has
approved the System for basic water quality treatment.
The proposed Stormfilter will be maintained by the Owner under a long term maintenance agreement with the
manufacturer. A water quality vault would also be maintained by the Owner as required by the City.
4*0
Special Requirements
1. Critical Drainage Areas — Project is not within a designated critical drainage area.
2. Compliance With An Existing Master Drainage Plan — Project is not within an area covered by an
approved Master Drainage Plan.
3. Conditions Requiring A Master Drainage Plan — Project is not a Master Planned Development, a
Planned Unit Development, a subdivision with at will have more than 100 lots, a commercial
development that will construct more than 50 acres of impervious surface, or will not clear more than
500 acres within a drainage sub -basin so a Master Drainage Plan is not required.
4. Adopted Basin Or Community Plan — Project is not within an area with an adopted plan.
5. Special Water Quality Controls — The project proposes discharge to a conveyance system that
eventually outfalls to a stream that runs through Gene Coulon Beach Park and discharges to Lake
Washington. See Section 3 Off Site Analysis. Water quality treatment for impervious area subject to
vehicular use will be required as indicated by City of Renton codified amendments to the KCSWDM
as noted above.
6. Coalescing Plat Oil/Water Separators — The project will not construct more than 5 acres of
impervious surface.
7. Closed Depressions — Proposed project will not discharge runoff to an existing closed depression.
8. Use of Lakes, Wetlands or Closed Depressions for Peak Rate Runoff Control — The project will not
use a lake, wetland or closed depression for.peak rate runoff control.
9. Delineation of 100 Year Floodplain — The Proposed project site does not contain or abut a stream,
lake, wetland or closed depression.
10. Flood Protection facilities for Type I and 2 Streams — The proposed project does not contain or abut
a Class 1 or 2 that has a flood protection facility.
11. Geotechnical Analysis and Report — A geotechnical analysis should not be required for the
construction of the stormwater facilities, however a geotechnical study will be performed for the site
and the Engineer will include information regarding drainage recommendations. A copy of the
geotechnical study will be included in the final TIR.
12. Soils Analysis And Report — The soils analysis will be included in the geotechnical report noted above
and the information will be included in the final TIR.
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Dodds
Consulting
Engineers
TECHNICAL INFORMATION REPORT
FOR
LEGACY PARTNERS
"THE BLUFFS"
PHASE I & 2
RENTON, WASH
Prepared by: Bruce J. Dodds
Approved by: Bruce J. Dodds, P.E., L.S.
Date: July, 1999
Project No: 97169
CI OF RE ON
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JUL 2 21999
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4205 -148th Avenue N.E. Bellevue, WA 98007 Tel. 425.86 1.4928 Fax. 425.885.7963
III. OFFSITE & LEVEL ONE DOWNSTREAM ANALYSIS, PHASE 1
The existing conditions at the Bluffs are the same today as they were when the EIS was
prepared in 1989. The design for both Phases, and particularly for Phase 1 for this TIR, is
predicated on the fact there is adequate downstream capacity so that no detention is
required or provided per KCSWM Manual 1.2.3 core requirement #3, exemptions. To
accomplish this reference will be made in part to the EIS drainage calculations, a full
copy of which is included in the Appendix.
The following two pages contain reproductions of two exhibits from the EIS drainage
calculations which show the original topography/drainage basins for the subject site and
for Marina Landing (Exhibit III -A, "Pre -development Basins") and the downstream
conveyance system (Exhibit III -B, "Downstream Culverts"). As the EIS drainage study
states, the topography shown on Exhibits III -A and B is from 1960 era City of Renton
maps, and therefore does not represent current conditions but does show the drainage
basins for each of the culverts prior to the diversions made by Marina Landing's
development. Exhibit III -A is included mainly to show the original drainage
basins/patterns and III -B is included to show downstream culvert number designations.
Exhibit III -C shows the basins as they will exist after construction of Phase 2 of The
Bluffs. The only significant difference between these basin maps is that on map III -B
sub -basin F and G are shown to drain through culvert #6 to #11 and then to Lake
Washington where this is not the case on III -C. Flows from culvert #2 will now be
redirected back through culvert #5 as they existed prior to construction of Marina
Landing. The remainder of basin F plus a portion of basin G will continue to flow to
culvert #6, the upper portion of basin G draining to the hole west of I-405, the hole never
having drained to culvert #6 in any event but still considered to do so in the EIS drainage
report. The remainder of the downstream analysis is contained on the following pages:
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Planning'- Engineering - Surveying JOB NO.
L)oL)DsGnINEERsiNc. 4205 -148th Avenue NE Suite 200
Bellevue, Washington 98007 DATE 1 '11 '9
Tel. 425-885-7877 Fax 425-885-7963
E Mail. Office@DElontine.com BY ?-) Down
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DODDS
Planning • Engineering • Surveying JOB NO.
4205 -148th Avenue NE Suite 200
Bellevue, Washington 98007 DATE t'
9—
Tel. 425-885-7877 Fax. 425-885-7963
E Mail. Office@DElontine.com fice@DElonline.com BY
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i-- ----- 1/21/99Dodds Engineers, Incorporated page 1
i
6 THE BLUFFS AT LAKE WASHINGTON, PHASE 1
.......{• DOWNSTREAM CAPACITY ANALYSIS
------- ----------
--- BASIN SUMMARY ti
-
.............
(}
--;---�--�--�--�--BASIN ID: 100P1 NAME: PHASE 1 100YR. EVENT, FULL BSN
..... '
+ SCS METHODOLOGY
___: TOTAL AREA.......: 12.20 Acres BASEFLOWS: 0.00 cfs
RAINFALL TYPE..... USER1 PERVIOUS AREA ___
PRECIPITATION..... 3.90 inches AREA... 5.00 Acres
TIME INTERVAL....: 10.00 min CN....: 81.00
TIME OF CONC.....: 10.00 min IMPERVIOUS AREA
. ABSTRACTION COEFF: 0.20 AREA... 7.20 Acres
CN.... 94.00 - ...... PEAK RATE: 10.59 cfs VOL: 2.69 Ac -ft TIME: 470 min
...........
__
..,.
SHEET OF
- - -
_ Planning - Engineering • Surveying
:D DODOS GINEERS INC. _ 4205 148th Avenue NE Suite 200
Bellevue, Washington 98007
Tel. 425-885-7877 Fox. 425-885-7963
E Mail. Ofce@DElonline.com
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Planning - Engineering - Surveying
420.5 -148th Avenue NE Suite 200
Bellevue, Washington 98007
Tel. 425-885-7877 Fox. 42S -88S-7963
E Mail. Office@DE[online,com
JOB NO. 9-1
DATE
BY-
III. OFFSITE & LEVEL ONE DOWNSTREAM ANALYSIS, PHASE 2
The drainage conditions at Phase 2 of the Bluffs are almost the same today as they were
when the EIS was prepared in 1989. The design for both Phases 1 and 2 is predicated on
the fact there is adequate downstream capacity so that no detention is required or
provided per KCSWM Manual 1.2.3 core requirement #3, "exemptions." To show this is
the case, reference will be made in part to the EIS drainage calculations, a full copy of
which is included in the Appendix.
The following foldout page shows the drainage basins contributing flows to Phase 2.
This map is a composite of the project site's existing topography, a worksheet site plan
overlaid on the topography (the southern portion of which also shows proposed grading
for the entry road), asbuilt drainage plans from the WSDOT for I-405 (most current) and
the topography on the east side of I-405 taken from the drainage basin map used in the
EIS. This map, together with the map on the page following, show that WSDOT has
made alterations to the I-405 drainage system from that described in the EIS, in particular
with reference to drainage basin 8 as defined in the EIS. Notice on the EIS map this
basin is shown draining to the southern portion of the Phase 2 project site. With the
changes made by WSDOT, this drainage now is directed south along the off -ramp so
basin 8 no longer contributes flow to the site. This may have been altered by the state
because the flows from the original system backed up and formed a pond east of the
railroad embankment, and thereafter overflowed and washed out the embankment (see
grading plan topography). We have confirmed there is no longer drainage from I-405
entering this swale where the washout occurred.
The other change which will occur as a result of this project's construction is the I-405
flows now entering the "Hole" shared by the project and WSDOT (see callouts 21 and 14
on the WSDOT plans for discharge pipe lying east of and between the third and second
most northerly phase 2 buildings). Where flows from this basin (EIS basin 3) now are
captured by the hole and percolate into the soil, this project will route those flows through
its conveyance system directly to Lake Washington.
On the following pages is a set of calculations which show the downstream system is
capable of accepting flows up to and above the 100 year event for the ultimate
development of the basin upstream of the conveyance system analyzed. Note the final
configuration of this site will represent the maximum development (i.e. increase in flow)
which could reasonably be expected to burden the downstream system.
I,
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Planning - Engineering - Surveying
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4205 -148th Avenue NE Suite 200
Bellevue, Washington 98007
%I.425-885-7877 Fax. 425-885-7963
E Mail. Ofce@DElonline.com
JOB NO. `I
DATE
BY '�D�D
:e,
DODDS
Planning • Engineering • Surveying JOB NO. -)11 +
420S -148th Avenue NE Suite 100 _
Bellevue, Washington 98007 DATE
Tel. 425-885-7877 Fax. 42S -88S-7963 Q.
E Mail, Ofce@DElonline.com BY
-... - . -
.. ...s ,
Dodds Engineer Incorporated _
<- <... -- PHASE 2.. .
THE BLUFFS AT LAKE WASHINGTON, N
DOWNSTREAM CAPACITY ANALYSIS
AND WATER QUALITY CALCULATIONS
BASIN SUMMARY
_.
BASIN ID: 10OP2
NAME: 100yr
evnt.to 12IN
LK W CLVT
SCS METHODOLOGY
TOTAL AREA........
17.69 Acres
BASEFLOWS:
0.00
cfs
RAINFALL TYPE....:
USER1
PERVIOUS AREA
PRECIPITATION.....
3.90 inches
AREA...
12.07
Acres
TIME INTERVAL.....
10.00 min
CN.....
85.00
- -
TIME OF CONC.....:
34.00 min
IMPERVIOUS
AREA
..ABSTRACTION
COEFF:
0.20
AREA..:
5.62
Acres
i....
CN....:
98.00
.
PEAK RATE: 10.79
cfs VOL- 3.97
Ac -ft TIME:
480 min
- ;.
BASIN ID: 25P2
NAME: 25YR.
TOTAL DEV SITE FLOW
SCS METHODOLOGY
j
-
:-:-
TOTAL AREA.......:
17.69 Acres
BASEFLOWS:
0.00
cfs
---:-
RAINFALL TYPE ....:
USER1
PERVIOUS AREA
PRECIPITATION....:
3.50 inches
AREA..:
12.07
Acres
-
TIME INTERVAL....:
10.00 min
CN....:
85.00
I°
-
TIME OF CONC.....:
34.00 min
IMPERVIOUS
AREA
ABSTRACTION COEFF:
0.20
AREA..:
5.62
Acres i
CN....:
98.00
-
PEAK RATE: 9.24
cfs VOL: 3.43
Ac -ft TIME:
480
min I
BASIN ID: 1OP2 NAME: 10YR TOTAL DEV SITE FLOW
SCS METHODOLOGY
TOTAL AREA.......
RAINFALL TYPE....:
PRECIPITATION....:
:.TIME INTERVAL....:
TIME OF CONC.....:
ABSTRACTION COEFF:
PEAK RATE:
17.69 Acres BASEFLOWS: 0.00 cfs
USER1 PERVIOUS AREA
3.00 inches AREA..: 12.07 Acres
10.00 min CN....: 85.00
34.00 min IMPERVIOUS AREA
0.20 AREA..: 5.62 Acres
CN..... 98.00
s VOL: 2.77 Ac -ft TIME: 480 min
-- 4
Planning - Engineering - Surveying JOB NO.
4205 -148th Avenue NE Suite 200
DODDS INC. Bellevue, Washington 98007 DATE
Tel. 425-885-1877 Fox. 42S-885-7963 0
'b EMoil.0fce@DElonline.com By Ib
------------------ ......... .......... ........
. . . .......... . .........
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............ .. ...
Deveite.pks
Flow Frequency Analysis ......
Time Series File:devsite.tof
Pro,ject Location.Sea-Tac
it
A
---Annual Peak Flow Rates --- ----- Flow Frequency Analysis -------
Flow Rate Rank Time of Peak' Peaks Rank Return Prob
(CFS)-, (CFS) Period
2.44 4 2/09/01- 2.00 5.21 1 100.00 0.990
1.75 7 1/05/02 16:00 2.96 2 25.00 0.960 it
2.98 2 2/27/03 7:00 2.56 3 10.00 0.900
1.62 8 8/26/04 2:00 2.44 4 5.00 0.800 it
i
2.02 6 10/28/04 16:00 2.39 5 3.00 0.667 t
2.56 .3 1118106 16.00' 2.02 6 2.00 0.500
2.39 5 11/24/06 3:00 1.75' 7 1.30 0.231
it
5.21 1 1/09/-08 6 . 00' 1.62 8 1.10 0.091 it
Computed Peaksi
4.47 50.00 0.980
4--J
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Planning - Engineering - Surveying
DODDS ENGINEERS INC. 4205 -148th Avenue NE Suite 200
Bellevue, Washington 98007
%1.425-88S-7877 Fox. 425-885-7963
E Mail, Office@DElontine.com
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SHEET Ar OF
Planning - Engineering - Surveying JOB NO.
DODDS NG;1NEER;ShV)C.E_,_ 4205 -148th Avenue NE Suite 200
Bellevue, Washington 98007 DATE
Tel. 425-885-7877 Fox. 425-885-7963
E Mail. Office@DElonline.corn BY 0
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..................... .. ...
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FIGURE 4.2.1.F NOMOGRAPH FOR SIZING CIRCULAR DRAINS FLOWING FULL- J:
-1,000 : --:-•-}--•---`--:-•-}---`--•-
=-goo i.. ................ .
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-700
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.0003 Minimum _44! _4 --- i_: --- i ---
400 .0004 0001 Allowable ............. . .......
vielocl Lj.
.0005
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3.0
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0008 .0002 Full)
120 N.001 <-j i---I--.---I- �--i--
-108 q--•- -- ---
.0003 1-1 t i t
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00 .0004 - ....... - ------
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-78
1 F o .003 ------ 1_1
.0008
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100
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az -2 .05
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lu -10
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a
SAMPLE USE
7 -8
24" dia. CMP 0 2% slope yields
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-20.0
1
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4
Values per Manning's equation
.......
Q 1.4-9 ) A R 213 So /z
-
3
n
-30.0
This table can be converted
...........
to other "n" values by applying
2
formula:
-
.... . .....
-40.0
+- Q1 =
Q2 nl
9/l/98
---------------
.. . ......
......... ....... ......... . ...... ..
. . . . . . . . . .
............. ......
............ . . . . . ...
. . ... . . . . .
1998 Surface Water Design Manual
..... ............... ...............
Planning - Engineering - Surveying JOB NO.
DODDS ENGINMS INC. 4205 -148th Avenue NE Suite 200 -�b
Bellevue, Washington 98007 DATE
Te1.425-885-7877 Fox. 425-885-7963
E Mail. Office@DElonline.com BY ?D
------
..........
..........
FIGURE 4.3.1.3
L HEADWATER DEPTH FOR SMOOTH INTERIOR PIPE CULVERTS WITH INLET CONTROL
I i i , -
..•.. . .. ----------
IOU
10,GOO
.......
168
8,000
EXAMPLE
156
6,000
4" tft*
42120da
5,000
,:1.chm
144
132
4,000
IF Kw
.............
3,WO
ONO
120
. . . . .
2, 13W
(2) 2.1 7.4
------- --
108
2.2 7.7
----------
96
in Am
1,000
.. ..............
..........
Boo
(3)
ENTRANCE TYP
84
600
... .........
500
400
300 —2.
....... ........ —"; ....... 72
1.5
T — -------
...........
60 200
1, 1— z 1.5
—64 z
...... . .......100
w —48
so
60
LL
42 yso 1.0
0 o H ENTRANCE 0
ALE 1.0
...... ............ 40 TYPE Ic
LU .9
w
36 30 (1) Squmedgewith
h -den
33 a
dli
2 (2) Groove and with
30 -C
ILI
le-dwall .8
(3) Gratimps lend .8
127 pimejecting
-------------- ......... 10
8 .—
–24
.7
7
6
To use scale (2)
or (d) project
–5
. . . ....... –21 11 scale (1), then
. 4 U545tralght Inclined line through
..........
0 Ad 0 ..W., or .
.. . ...... ...... 3 .6
Illustrated. .6 .6
——
....... 18
—2
15
7
5 5
.5
12
SQUARE EOGEWlTH
HEADWALL,
IIS
PLAN
GROOVE END=
,,HEADWALL
DESPL-AN (2)
GROOVE END
PROJECTING
__%1998 Surface Water Design Manual
9/l/98
443
. . . . .... ... ... ......... .....
............ . . . . . .
.. . ......... . .............. . . . .
•
.............. ------ ...... ...........
77-51)•
:S•.
... . .............. ------ ........... i– ............ –
J-1
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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.
This document is not intended for use as a survey product. King County shall not be liable for any general, special, indirect, incidental, or consequential LQ
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 'ale of
this map or information on this map is prohibited except by written permission of King County- King County
Date: 1/1612014 Source: King County MAP - Sensitive Areas (http:i/w .metrokc.gov/GiSriMAP)
I
Sensitive
Areas
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MY 1890ft
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.
This document is not intended for use as a survey product. King County shall not be liable for any general, special, indirect, incidental, or consequential LQ
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 'ale of
this map or information on this map is prohibited except by written permission of King County- King County
Date: 1/1612014 Source: King County MAP - Sensitive Areas (http:i/w .metrokc.gov/GiSriMAP)
I
z
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NE 17THW
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LNN STaf ST
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Z, �u
>
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MY 1890ft
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.
This document is not intended for use as a survey product. King County shall not be liable for any general, special, indirect, incidental, or consequential LQ
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 'ale of
this map or information on this map is prohibited except by written permission of King County- King County
Date: 1/1612014 Source: King County MAP - Sensitive Areas (http:i/w .metrokc.gov/GiSriMAP)
I
I Sensitive Areas I
Legend
Highlighted Feature Floodway
County Boundary ��1� 100 Year Floodplain
X Mountain Peaks Channel Migration Hazard
Highways Areas
11 Incorporated Area MODERATE
Modmne
Iir'gh
Shaded Relief
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.
This document is not intended for use as a survey product. King County shall not be liable for any general, special, indirect, incidental, or consequential a
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
rmKing County
this map or information on this map is prohibited except by written permission of King County.
Date: 1/16/2014 Source: King County NAP - Sensitive Areas(http://www.metrokc.gov/GIS(MAP)
Streets
SEVERE
lllghWN
®
Sole Source Aquifer
Arterials
"7"
SAO Wetland
Local
SAO Landslide
Parcels
SAO Coal Mine
Wildlife Network
SAO Seismic
SAO Stream
SAO Erosion
Mass 1
Chinook Distribution
Class 2 (3ef ert oral
■
Sensitive Area Notice on Title
C lass 2 Salmon al
Drainage Complaints
rr
C lass 5
'
Areas Susceptible to
•
uattsssff+od
Groundwater Contamination
i7Lakes
and Large Rivers
Streams
L°'"
(cont)
Modmne
Iir'gh
Shaded Relief
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.
This document is not intended for use as a survey product. King County shall not be liable for any general, special, indirect, incidental, or consequential a
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
rmKing County
this map or information on this map is prohibited except by written permission of King County.
Date: 1/16/2014 Source: King County NAP - Sensitive Areas(http://www.metrokc.gov/GIS(MAP)