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HomeMy WebLinkAboutMiscLE
TAC O M A SEATTLE
TECHNICAL
INFORMA TION
REPORT
PREPARED FOR:
Renton School District #403
7812 South 124th Street
Seattle, WA 98178
PROJECT.•
Nelsen Middle School Site
Improvements
Renton, Washington
211128.10
PREPARED BY:
Michael R. Norton, P.E.
Project Engineer
REVIEWED BY.'
Doreen S. Gavin, PE, LEER° AP
Vice President
March 2012
Civil Engineers • Structural Engineers • Landscape Architects • Community Planners • Land Surveyors • Neighbors
TECHNICAL
INFORMATION
REPORT
PREPARED FOR:
Renton School District #403
7812 South 124th Street
Seattle, WA 98178
PROJECT:
Nelsen Middle School Site
Improvements
Renton, Washington
211128.10
PREPARED BY.-
Michael
Y:
Michael R. Norton, P.E.
Project Engineer
REVIEWED BY:
Doreen S. Gavin, PE, LEED° AP
Vice President
March 2012
I hereby state that this Technical
Information Report for Nelsen Middle
School Site Improvements has been
prepared by me or under my
supervision, and meets the standard
of care and expertise that is usual
and customary in this community for
professional engineers. I understand
that the City of Renton does not and
will not assume liability for the
sufficiency, suitability, or
performances of drainage facilities
prepared by me.
TECHNICAL
INFORMA TION
REPORT
PREPARED ICOR:
Renton School District No. 403
7812 South 124th Street
Seattle, WA 98178
PROJECT. -
Nelsen Middle School Site
Improvements
Renton, Washington
211128.10
PREPARED BY:
Michael R. Norton, P.E.
Project Engineer
REVIEWED BY.-
Doreen S. Gavin, PE, LEED° AP
Vice President
March 2012
TABLE OF CONTENTS
SECTION PAGE
1.0 Project Overview.............................................................................................
1
1.1 Purpose and Scope................................................................................ 1
1.2 Existing Conditions .................... ........ 1
1.3 Post -Development Conditions.................................................................. 2
2.0 Conditions and Requirements Summary.............................................................. 3
2.1 Core Requirements................................................................................ 3
2.2 Special Requirements............................................................................. 5
3.0 Off -Site Analysis ....................................... ............. .. 5
3.1 Downstream Analysis............................................................................. 5
3.2 Upstream Analysis................................................................................. 8
3.3 Off -Site Design...................................................................................... 8
4.0 Flow Control and Water Quality Facility Analysis and Design .................................. 8
4.1 Flow Control.........................................................................................
8
4.2 Water Quality........................................................................................ 9
5.0 Conveyance System Analysis and Design............................................................10
6.0 Special Reports And Studies.............................................................................10
7.0 Other Permits.................................................................................................10
8.0 TESC Analysis and Design................................................................................10
9.0 Bond Quantities, Facility Summaries, and Declaration of Covenant ........................11
10.0 Operations and Maintenance Plan.....................................................................11
11.0 Conclusion.....................................................................................................11
APPENDICES
Appendix A Exhibits
Figure 1 ..............TIR
Worksheet
Figure 2..............Vicinity
Map
Figure 3 ..............
Existing Conditions Map
Figure 4 ..............
Developed Conditions Map
Figure 5..............King
County Water Features Map
Figure 5 ..............
City of Renton Groundwater Protection Areas Map
Figure 7 ..............
City of Renton Flow Control Applications Map
Figure 8 ..............
King County Water Quality Applications Map
Figure 9..............City
of Renton Sensitive Areas — Steep Slopes Map
Figure 10 ............City
of Renton Aquifer Protection Zones Map
Figure 11 ............City
of Renton Sensitive Areas — Erosion Hazard Map
Figure 12 ............
City of Renton Sensitive Areas — Flood Hazard Map
Figure 13 ............City
of Renton Zoning Map
Figure 14 ............
City of Renton Sensitive Areas — Landslide Hazard Map
Figure 15 ............
Flood Insurance Rate Map
Appendix B Soils Information
Figure 1 .............. Natural Resource Conservation Service Data
Figure 2 .............. City of Renton Soil Survey Map
Appendix C Downstream Analysis
Figure 1 .............. Drainage System Map, Upstream Tributary Map
Figure 2 .............. Drainage System Map, On -Site
Figure 3 .............. Drainage System Map, Downstream
Appendix D Summary of Drainage Facilities
Figure 1 .............. Existing Conditions Drainage Basin Map
Figure 2 .............. Developed Conditions Drainage Basin Map
Figure 3 .............. Flow Control Calculations
Figure 4 .............. Conveyance System Analysis
Appendix E Geotechnical Report
Appendix F Bond Quantities, Facility Summaries, and Declaration of Covenant
Figure 1 .............. Bond Quantities Worksheet
Figure 2..............Flow Control and Water Quality Facility Summary Sheet
Figure 3 .............. Declaration of Covenant
Appendix G Operation and Maintenance Manual
Appendix H TESC Analysis and Design
Figure 1 ..............Temporary Sediment Pond Calculations
1.0 PROJECT OVERVIEW
1.1 Purpose and Scope
The Nelsen Middle School project proposal is to provide improved athletic facilities on a
29.54 -acre site located at 2403 Jones Avenue South in Renton, WA. Improvements
include the construction of a new baseball field; new soccer field with asphalt track; ADA
paths from the existing building to the new athletic facilities; landscaping; and
stormwater conveyance and flow control facilities. The project site is defined as the 6.84
acres which will be disturbed for the construction of these proposed improvements. This
report describes the analysis and design of the stormwater facilities.
The 2009 King Country Surface Water Design Manua! (KCSWDM) and City of Renton
Amendments to the King County Surface Water Design Manual (February, 2010),
establish the methodology and design criteria used for the project. The King County
Runoff Time Series (KCRTS) software program, developed by the King County
Department of Natural Resources, was used to calculate runoff and design stormwater
flow control facilities. The Rational method was used to determine conveyance capacities.
1.2 Existing Conditions
The project site is at the existing Nelsen Middle School located at 2403 Jones Avenue
South in Renton, Washington (See Appendix A, Figure 2 for Vicinity Map), King County
Parcel No. 2423059061. The parcel is zoned R-8, Residential 8du/ac according to the City
of Renton Zoning Map (See Appendix A, Figure 13). The project site encompasses 29.54
acres within the Black River Drainage Basin as delineated by the icing County Water
Features Map (see Appendix A, Figure 5). There are no wetlands on the project site.
According to the City of Renton Groundwater Protection Areas Map (See Appendix A,
Figure 6), the project site is not within a groundwater protection area.
The Nelsen Middle School facility is bound to the north and northwest by multi -family
residences off of Benson Road South, to the southwest and east by trees and vegetation,
and to the south by Spring Glen Elementary School.
Site soils have been classified as Map Unit AgC — Alderwood gravelly sandy loam, 6 to 15
percent slopes, according to the WA 633 Soil Survey of King County Area, Washington,
provided by the Natural Resource Conservation Service. Permeability is moderately rapid
in the surface layer and subsoil and very slow in the substratum. Roots penetrate easily
to the consolidated substratum where they tend to mat on the surface. Some roots enter
the substratum through cracks. Water moves on top of the substratum in winter.
Available water capacity is low. Runoff is slow to medium, and the hazard of erosion is
moderate. See Appendix B, Figure 1 for data provided by the Natural Resource
Conservation Service.
The City of Renton Soil Survey Map, included as Appendix B, Figure 2, also classifies on-
site soils as AgC — Alderwood gravelly sandy loam, 6 to 16 percent slopes.
A Geotechnical Engineering Report was created in May, 2011 by Associated Earth
Sciences, Inc. Subsurface conditions were explored by advancing 13 exploration borings
(EB -1 through EB -13) to gain subsurface information about the site. Representative
samples of subsurface soils were obtained from each exploration boring at approximately
2.5- to 5 -foot depth intervals. The Geotechnical Engineering Report is included in its
entirety as Appendix E.
Fill
000
Existing fill was encountered in all exploration borings except for EB -1, EB -2 and EB -5.
The fill ranged in thickness from 4 to 31 feet within the explorations and consisted of
loose to medium dense silty sand and gravel with scattered organics.
Stratified Drift Sediments (Undifferentiated)
All of the explorations encountered medium dense to very dense brownish gray silty sand
with gravel and sand lenses and beds, with thick sand beds encountered in exploration
borings EB -5 and EB -9.
Weathered Tertiary Bedrock
At the location of exploration boring E13-3, the stratified drift was underlain by a highly
fractured silty sand with gravel, which appeared as "chips" in the bedrock. Where
encountered, the weathered bedrock extended beyond the depth explored.
Groundwater
An observation well was placed in exploration boring E8-9 at the time of drilling to
determine if a static ground water level was present and to measure its depth. On April
21, 2011, a static water level was measured at a depth of 33.81 feet.
Groundwater seepage was encountered in a thick sand bed in exploration boring EB -9 at
the time of drilling. Moist to wet soil was encountered at various depths within the
existing fill, suggesting that perched water should be expected throughout the site.
AHBL, Inc. compiled a topographic survey for the Nelsen Middle School property. This
survey was used as a base map to delineate on-site drainage basins. (See Appendix A,
Figure 3 — Existing Conditions Map.)
The existing school includes a main building on the southeast part of the site, with
athletic fields to the north and west, and paved parking areas to the south, northeast
and west of the main building. Site topography is relatively flat to gently sloping, with a
sloped grassy "step" which leads downward to the north and west to existing sports field
areas. The ground surface continues steeply downward from the subject site,
approximately 15 to 20 vertical feet to the north and roughly 25 vertical feet to the west,
to nearby properties. A wooded corridor with areas of ponded water lies to the east.
In general, runoff from the existing baseball fields and track along the western portion of
the site moves as sheet and subsurface flow to the northwest to exit the site. Drainage
from the northern field area enters a series of underdrains and is piped via tightline
conveyance system to an existing storm drain manhole in the northern portion of the
western field areas before exiting the site. Refer to Section 3 of this report for the
complete off-site analysis.
1.3 Post -Development Conditions
Upon completion of construction, site improvements will include a new baseball field to
the northwest of the existing school, a new soccer field with asphalt track to the north of
the existing school, a flow control pond in the northwest corner of the project site, site
landscaping, an asphalt access road from the new soccer field/track to the flow control
pond, as well as site landscaping. (See Appendix A, Figure 4 for the Developed
Conditions Map.)
In general, the engineered drainage for the proposed project will not alter existing
drainage discharge locations from the site. Runoff from the new baseball field and soccer
field/track will be collected in a series of underdrains and piped via tightline conveyance
system to the flow control pond for controlled release to an existing storm drain line in
the northern portion of the western field area. This drainage design is in accordance with
flow control requirements for a duration standard matching forested site conditions. Pre -
and post -development flows are discussed in Section 4.1.3. Calculations are provided as
Appendix D, Figure 3 — Flow Control Calculations.
2.0 CONDITIONS AND REQUIREMENTS SUMMARY
2.1 Core Requirements
2.1.1 Core Requirement #1 — Discharge at the Natural Location
Currently, runoff from the existing baseball fields and track along the western
portion of the site moves as sheet and subsurface flow to the northwest to exit
the site. Drainage from the northern field area enters a series of underdrains
and is piped via tightline conveyance system to an existing storm drain manhole
in the northern portion of the western field area before exists the site.
In general, the engineered drainage system for the proposed project will not
alter existing discharge locations from the site. Runoff from the western and
northwestern areas will continue to move as sheet and subsurface flow to the
northwest to exit the site with the exception of the new baseball field, which
will be collected by a series of underdrains and conveyed to the detention pond.
Drainage from the new soccer field will be collected by underdrains and also
routed to the detention pond to be released to an existing storm drain line in
the northern portion of the western field area. Pre- and past -development flows
are discussed in Section 4.1.3. Calculations are provided as Appendix D, Figure
3.
2.1.2 Core Requirement #2 — Off -Site Analysis
ANBL staff performed a Level 2 Downstream Analysis on February 1, 2012. The
analysis included:
• Defining and mapping the study area.
• Reviewing available information on the study area.
• Field inspecting the study area.
• Describing the existing drainage system including its existing and predicted
problems, if any.
• Addressing mitigation of existing and potential flooding, erosion, or nuisance
problems.
Refer to Section 3.0 of this report for the full Off -Site Analysis.
2.1.3 Core Requirement #3 — Flow Control
The Nelsen Middle school project site is subject to duration standard matching
forested site conditions flow control per the City of Renton Flow Control
' ODOO
Application Map (See Appendix A, Figure 7). This detention standard matches
the flow duration of pre -developed rates for forested (historic) site conditions
over the range of flows extending from 50% of 2 -year up to the full 50 -year
flow, as specified in Table 1.2.3.A of the City of Renton Amendments to the
King County Surface Water Design Manual. The flow control requirement is
applied to the project site area of 6.84 acres. The hydrologic model used to
determine flows and durations is KCRTS.
2.1.4 Core Requirement #4 — Conveyance System
The new conveyance system is designed to convey and contain the 100 -year
peak flow (calculated using the Rational method) for the proposed site
improvements, assuming developed conditions for on-site tributary areas and
existing conditions for any off-site tributary areas. The design and calculations
for the new conveyance system are included in Appendix D, Figure 4.
2.1.5 Core Requirement #5 — Erosion and Sediment Control
An erosion and sediment control plan has been developed for this site in
accordance with Appendix D of the KCSWM. Extensive erosion control
measures will be provided due to the size of the project and the slopes along
the north and west property lines. Control measures will include limiting the
area to be disturbed, temporary sediment pond, catch basin sediment barriers,
silt fencing, temporary interceptor ditches with gravel check dams, and proper
cover measures.
2.1.6 Core Requirement #6 - Maintenance and Operations
A sample maintenance and operations manual is included in Appendix G.
2.1.7 Core Requirement #7 - Financial Guarantees and Liability
This project will comply with the financial guarantee requirements in Renton
Municipal Code Section 4-6-030, Paragraph J.
2.1.8 Core Requirement #8 - Water Quality
Section 1.2.8, Core Requirement #8 — Water Quality, of the City of Renton
Amendments to the King County Surface Manual States "A proposed project or
any threshold discharge area within the site of a project is exempt if it meets all
of the following criteria:
Less than 5,000 square feet of new PCIS that is not fully dispersed will be
added, and
Less than 5,000 square feet of new plus replaced PGIS that is not fully
dispersed will be created as part of a redevelopment project, and
c. Less than 35,000 square feet of new PGPS that is not fully dispersed will be
added."
The Nelson Middle School Site Improvement project does not involve the
creation of Pollution Generating Surfacing, and is therefore exempt from the
requirements of Core Requirement #8 — Water Quality.
2.2 Special Requirements
2.2.1 Special Requirement #1 - Other Adopted Area -Specific Requirements
The Nelsen Middle School site is located within the Black River drainage basin.
City and County basin requirements will be followed where applicable.
2.2.2 Special Requirement #2 - Flood Hazard Area Delineation
The City of Renton Sensitive Areas Flood Hazard Map (See Appendix A, Figure
12) indicates that the project site lies outside of any flood hazard areas.
FEMA Flood Insurance Rate Map 53033C0979F, dated May 16, 1995 (See
Appendix A, Figure 15) indicates that the project site lies within Zone X - Areas
determined to be outside the 500 -year floodplain.
2.2.3 Special Requirement #3 - Flood Protection Facilities
The project does not contain, will not construct, and is not adjacent to any
existing flood protection facilities.
2.2.4 Special Requirement #4 - Source Control
The proposed project is an educational facility; therefore, it does not fit the
definition of a commercial, industrial, or multi -family site for source control
purposes.
2.2.5 Special Requirement #5 - Oil Control
The project does not fit the definition of a high -use site; therefore, it is not
subject to oil control requirements.
2.2.6 Special Requirement #6 - Aquifer Protection Area
The project is not within an aquifer protection area as shown on the City of
Renton Aquifer Protection Zone Map (See Appendix A - Figure 10).
3.0 OFF-SITE ANALYSIS
3.1 Downstream Analysis
3.1.1 Task 1 - Study Area Definition and Maps
Nelsen Middle School proposes to provide improved athletic facilities on a 29.54
acre site located at 2403 Jones Avenue South in Renton, WA. Improvements
include the construction of a new baseball field; soccer field with asphalt track,
ADA paths from the existing building to the new athletic facilities; landscaping;
and stormwater conveyance and flow control facilities.
In developed conditions, site improvements will include a new baseball field to
the northwest of the existing school, a new soccer field with asphalt track to
the north of the existing school, and a detention pond in the northwest corner
of the project site.
There are four distinct areas on the project site which are separated by vertical
relief of between 10 and 20 feet; the existing school lies in the southeast
quadrant at an elevation of approximately 430 feet; the southwest quadrant, at
elevation of approximately 418 will be expanded to the north for the proposed
baseball field; the northeast quadrant, at an elevation of approximately 407 will
house the proposed detention facility; and the northeast quadrant, at an
elevation of approximately 422, is where the new soccer field and asphalt track
will be located.
The entire project site lies within the Black River Drainage Basin as delineated
by the King County Water Features Map (See Appendix A, Figure 5). There are
no wetlands on or in the vicinity of the project site. According to the City of
Renton Groundwater Protection Areas Map (See Appendix A, Figure 6), the
project site is not within a groundwater protection area.
In existing conditions, there are four discharge locations from the project site.
Stormwater from the western half of the site primarily moves as sheet and
subsurface flow to the northwest to exit the site at the northern and western
property lines. Drainage from the northern field enters a series of underdrains
and is piped via tightline conveyance system to an existing storm drain manhole
in the northwestern quadrant before existing the site. This discharge combines
with above mentioned sheet and subsurface flows exiting the site within 1/4 mile
downstream. Lastly, a portion of the northern field area moves as sheet and
subsurface flow and exits the project site at the northern property line. This
drainage does not combine with any other discharge from the project site.
AHBL staff performed a Downstream Analysis for each of the drainage paths
mentioned above. Drainage from the portion of the northern field exiting the
project site at the northern property line is labeled as "Path A", drainage exiting
the site along the western and remainder of the northern area is labeled as
"Path B", drainage exiting the site at the existing storm drain manhole is
labeled "Path C". Following the point of convergence of "Path B" and "Path C",
the drainage path is labeled as "Path D". (See Appendix C, Figure 3 for
downstream drainage system maps.)
3.1.2 Task 2 — Resource Review
The following resources were reviewed to discover any existing or potential
problems in the study area:
1. Adopted Basin Plans: The project site lies within the Black River Drainage Basin.
Requirements for the Black River Drainage Basin will be followed where
applicable.
2. Drainage Studies: AHBL developed a Technical Information Report in 2004 for
the Nelsen Middle School access reconfiguration project.
3. Off -Site Analysis Reports: AHBL staff has not located off-site analysis reports for
projects near the Nelsen Middle School Site Improvements project site.
FEMA Map: FEMA Flood Insurance Rate Map 53033C0979F, dated May 16, 1995
(See Appendix A, Figure 15) indicates that the project site lies within Zone X —
Areas determined to be outside the 500 -year floodplain.
6 000
Sensitive Areas Landslide Hazard Map: The off-site slopes to the north and west
of the project present a moderate hazard according to the City of Renton
Sensitive Areas Landslide Hazard (See Appendix A, Figure 14). Requirements for
Landslide Hazard areas will be followed where applicable. There are no wetlands
on or downstream of the project site.
Soils Information: Site soils have been classified by the WA633 Soil Survey of
King County Area, Washington and the City of Renton as Alderwood gravelly
sandy loam, 6 to 15 percent slopes (AgC) (see Appendix B, Figures 1 and 2).
Associated Earth Sciences, Inc. prepared a Geotechnical Engineering Report for
the project site, confirming the existence of fill, stratified drift sediments
(undifferentiated) and weathered tertiary bedrock on site. The Geotechnical
Engineering Report is included in its entirety as Appendix E.
Drainage Problems: To determine if there are any reported drainage problems
downstream of the site, AHBL reviewed the internet-based, King County iMAP
Stormwater Map Layer set. No drainage problems were on record for the Nelsen
Middle School Site Improvement project site or downstream of the site.
The resource review determined no existing or potential drainage problems,
existing/potential flooding problems, or erosion and water quality problems.
3.1.3 Task 3 — Field Inspection
Path A
On February 1, 2012 AHBL staff performed a Downstream Analysis of the
drainage system receiving stormwater runoff from the northern field exiting at
the northern property line.
Upon leaving the Nelsen Middle School property, runoff sheet flows within the
constraints of the Sunset Ridge Condominiums driveway approximately 575 feet
to Puget Drive SE, where it enters the tightline conveyance system within Puget
Drive SE and flows to the west for approximately 390 feet to Grant Avenue
South. Stormwater is then piped to the north for approximately 1,075 feet
where it is discharged to a ditch to flow to the northwest for approximately
2,800 feet to the I-405 right-of-way. Field observations found no evidence of
drainage related problems (erosion, overtopping, etc.) along Path A.
Path B
On February 1, 2012, AHBL staff performed a Downstream Analysis of the
drainage system from the western half of the site that discharges at the north
and west property lines. Stormwater runoff from this area parallels northern
and western property lines to combine at approximately the northwest corner of
the Nelsen Middle School property. From this point, it travels west as sheet and
subsurface flow approximately 335 feet to Benson Road South to combine with
runoff from Path C to form drainage Path D. Field observations found no
evidence of drainage related problems (erosion, overtopping, etc.) along Path
B.
Path C
The point of discharge from the subject site for Path C is an existing storm
drain manhole on the western property line approximately 260 feet south from
the northern property line. From this point, runoff is conveyed approximately
285 feet across the Westgate Condominium property to Benson Road South,
where it enters the tightline conveyance system on the east side of the roadway
to be conveyed approximately 390 feet north to combine with drainage from
Path B to form drainage Path D. Field observations found no evidence of
drainage related problems (erosion, overtopping, etc.) along Path C.
Path D
Path D, consisting of the combined runoff from Path B and Path C, continues
north within the Benson Road South conveyance system approximately 390 feet
before crossing to the conveyance system on the west side of Benson Road
South. Runoff is conveyed north approximately 100 feet before turning east and
entering the private conveyance system on Montclair Heights Apartments
property. Runoff is generally conveyed approximately 600 feet to a small pond.
Field observations found no evidence of drainage related problems (erosion,
overtopping, etc.) along this path.
3.2 Upstream Analysis
There are no off-site upstream tributary areas that contribute drainage to the athletic
fields. On-site, upstream runoff to the athletic fields comes from approximately 0.85
acre near the northwest corner of the existing Nelsen Middle School building and the
lower athletic fields.
See Appendix C, Figure 1 for upstream tributary areas.
3.3 Off -Site Design
Frontage improvements are not included with this submittal.
4.0 FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN
4.1 Flow Control
4.1.1 Existing Site Hydrology
Area (Acre)
Flow (cfs)
Till
Forest
Till
Grass
Impervious
Total
2-
Year
10-
Year
100 -
Year
1.42
5.20
0.22
6.84
0.330
0.597
1.31
4.1.2 Developed Site Hydrology
Area (Acre)
Flow (cfs)
Till
Forest
Till
Grass
Impervious
Total
2-
Year
14-
Year
100 -
Year
0
5.20
1.64
6.84
0.639
0.902
1.87
8 13000
4.1.3 Flow Control
Section 1.2.3 of the City of Renton Amendments to the King County Surface Water
Design Manual states that "all proposed projects, including redevelopment project, must
provide on-site flow control facilities to mitigate the impacts of increased storm and
surface water runoff generated by the addition of new impervious surface and any
related land conversion."
According to the -City of Renton Flow Control Application Map (Appendix A, Figure 7), the
Nelsen Middle School Site Improvement project is subject to the Flow Control Duration
Standard Matching Forested Conditions. The flow control duration standard requires
runoff from urban developments to be detained and released at a rate that matches the
flow duration of forested rates over the range of flows extending from '/x of the 2 -year
up to the 50 -year flow. Developed peak discharge rates shall match forested peak
discharge rates for the 2- and 10 -year return periods. Flow duration specifies the
cumulative amount of time that various flows are equaled or exceeded during a long-
term simulation using historic rainfall.
Flow control facilities are required to mitigate impacts of increased surface water runoff
generated by the addition of new impervious surface and replaced impervious surfaces
considered a targeted surface. Because this is a redevelopment project with a
construction cost of less than 50 percent of the assessed value, the replaced impervious
surfaces are not considered a targeted surface. Additionally, flow control facilities are
not required to mitigate impacts of existing pervious surfaces. Therefore, a flow control
facility is only required for the new impervious surface created by the redevelopment of
the track and athletic fields and the construction of the new walkways.
Based upon geotechnical explorations, the site soils are not conducive to infiltration.
Therefore a detention system is proposed for the project area.
For the hydrologic model for the redevelopment condition, the underdrained area of the
athletic fields are modeled as 75 percent pervious and 25 percent impervious per the
2009 KCSWDM, Table 3.2.2.C, KCRTS Cover Groups and Areas of Application. The Flow
Control Duration Standard was applied to control the flow durations and peaks to historic
site conditions for the target impervious surface area. The flow durations and peaks
were obtained by modeling the targeted impervious area (1.42 acres) as forest till.
Because the pervious area is not a target surface, it was modeled as grass, till in both
the pre -developed and the re -developed model conditions.
Flow control calculations were performed using Icing County Runoff Time Series (KCRTS).
Calculations are provided as Appendix D, Figure 3.
4.2 Water Quality
Section 1.2.8, Core Requirement #8 — Water Quality, of the City of Renton
Amendments to the King County Surface Manual States "A proposed project or
any threshold discharge area within the site of a project is exempt if it meets all
of the following criteria:
d. Less than 5,000 square feet of new PGIS that is not fully dispersed will be
added, and
e. Less than 5,000 square feet of new plus replaced PGIS that is not fully
dispersed will be created as part of a redevelopment project, and
9 13c)(33
f. Less than 35,000 square feet of new PGPS that is not fully dispersed will be
added."
The Nelson Middle School Site Improvement project does not involve the
creation of Pollution Generating Surfacing, and is therefore exempt from the
requirements of Core Requirement #8 — Water Quality.
5.0 CONVEYANCE SYSTEM ANALYSIS AND DESIGN
The conveyance system was analyzed by means of the Rational Method in accordance with Table
3.2 of the KCSWDM. "Stormshed 2G" software was used for the analysis. The system was
designed for the 25 -year storm event, and checked for capacity for the 100 -year event. A
backwater analysis was performed for both the 25- and 100 -year events assuming a submerged
outlet into the detention pond. Backwater elevations at all structures are below the 0.5 foot
clearance threshold for both events with the closest backwater to rim distance of kXk feet during
the 100 -year event. (See Appendix D, Figure 4 for conveyance calculations)
6.0 SPECIAL REPORTS AND STUDIES
Associated Earth Science, Inc. prepared a Geotechnical Report for the subject site in
May, 2011, which is included in its entirety as Appendix E.
7.0 OTHER PERMITS
To the best of our knowledge, a grading permit and the National Pollutant Discharge
Elimination System (NPDES) Stormwater Permit are the only permits required for the
proposed project.
8.0 TESC ANALYSIS AND DESIGN
The proposed development shall comply with guidelines set forth in the KCSWDM. The
plan includes erosion/sedimentation control features designed to prevent sediment -laden
runoff from leaving the site or from adversely affecting critical water resources during
construction.
The following measures will be used to control erosion/sedimentation processes:
• Clearing Limits: All areas to remain undisturbed during the construction of the project will
be delineated prior to any site clearing or grading.
• Cover Measures: Disturbed areas shall be covered as required in Appendix D of the
2009 KCSWDM.
• Perimeter Protection: Filter fabric fencing for ditch and site runoff protection will be
provided at downstream site perimeters.
• Sediment Retention: Surface water collected from disturbed areas will be routed through a
sediment pond prior to release. Design calculations for the sediment pond are provided as
Appendix H, Figure 1.
• Construction Entrance: Existing driveways will serve as points of ingress/egress for
construction related traffic. Sweeping and the implementation of a wheel wash will occur if
sediment is deposited on on-site driveways or neighboring rights of way.
Catch Basin Sediment Protection: Filter fabric protection will be provided on all new and
existing drainage collecting structures downstream of construction activities.
Surface Water Control; Interceptor ditches with gravel check damswill be used to direct
runoff from construction areas to the sediment pond.
Dust Control: Dust control measures will be implemented when exposed soils are dry to
the point that wind transport is possible, and roadways, drainage ways, or surface waters
are likely to be impacted.
9.0 BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF
COVENANT
To establish appropriate bond amounts, the City of Renton Bond Quantities Worksheet
will be provided in the final submittal as Appendix F, Figure 1.
Following approval of the engineering plans a Flow Control and Water Quality Facility
Summary Sheet will be submitted along with an 8-1/2 inch by 11 inch plan sketch for
each facility proposed for construction per KCSWDM requirements. See Appendix F,
Figure 2 for an example of the sheet.
Prior to permit approval, a Declaration of Covenant will be signed and recorded and will
be provided as Appendix F, Figure 3.
10.0 OPERATIONS AND MAINTENANCE PLAN
Operations and maintenance will be the responsibility of the Owner. All drainage facilities
shall be maintained and operated in compliance with the City of Renton and King County
maintenance standards. See Appendix G for the Maintenance Requirements for privately
maintained drainage facilities.
11.0 CONCLUSION
This site has been designed to meet or exceed the requirements of the 2009 King County
Surface Water Design Manual and the City of Renton Amendments to the King County
Surface Water Design Manual (February, 2010). The site incorporates flow control
facilities to detain stormwater draining from the project site. Flow calculations/modeling
utilized the City of Renton standards for sizing stormwater conveyance networks, and
flow control facilities.
11 GIM03
This analysis is based on data and records either supplied to or obtained by AHBI_, Inc. These
documents are referenced within the text of the analysis. The analysis has been prepared
Utilizing procedures and practices within the standard accepted practices of the industry. We
conclude that this project, as proposed, will not create any new problems within the existing
downstream drainage system.
AHBL, Inc.
Michael R. Norton, P.E.
Project Engineer
MRN/Isis
February, 2009
Q:12011\211128\10_CIV�NON_CAD�REPORTS\Tecjnicak Information Report\2012-01-23 TIR (Draft).docx
12 MID190
APPENDIX A
Exhibits
Figure 1..0......
TIR Worksheet
Figure 2.........
Vicinity Map
Figure 3.........
Existing Conditions Map
Figure 4.........
Developed Conditions Map
Figure 5.........
King County Water Features Map
Figure 6 .........
City of Renton Groundwater Protection
Areas Map
Figure 7.........
City of Renton Flow Control Applications
Map
Figure 8.........
King County Water Quality Applications
Map
Figure 9.........
City of Renton Sensitive Areas — Steep
Slopes Map
Figure 10.......
City of Renton Aquifer Protection Zones
Map
Figure 11.......
City of Renton Sensitive Areas — Erosion
Hazard Map
Figure 12.......
City of Renton Sensitive Areas — Flood
Hazard Map
Figure 13.......
City of Renton Zoning Map
Figure 14..0....
City of Renton Sensitive Areas — Landslide
Hazard Map
Figure 15.......
Flood Insurance Rate Map
KING COUVJY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Project Engineer
Company
Phone
❑
DFW HPA
❑
COE 404
❑
DOE Dam Safety
❑
FEMA Floodplain
❑
COE Wetlands
❑
Other
❑ Shoreline
Management
❑ Structural
Rockery/Vault/
❑ ESA Section 7
Pdt F?LAN¢11±fDFI='�R. xli41114ONr
c .
l M
Technical Information Report Site Improvement Plan (Engr. Plans)
Type of Drainage Review Full / Targeted / Type (circle one): Full I Modified I
(circle)Large Site Small Site
Date (include revision Date (include revision
dates): dates):
Date of Final: Date of Final:
Type (circle one): Standard I Complex / Preapplication / Experimental I Blanket
Description (include conditions in TIR Section 2)
Date of Approval
2049 Surface Water Design Manual
I
1/9/2009
R-
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
❑ River/Stream
❑ Steep Slope
❑ Lake
❑ Erosion Hazard
❑ Wetlands
❑ Landslide Hazard
❑ Closed Depression
❑ Coal Mine Hazard
❑ Floodplain
❑ Seismic Hazard
❑ Other
❑ Habitat Protection
Ll
Soil Type
Slopes
❑ High Groundwater Table (within 5 feet) ❑ Sole Source Aquifer
❑ Other ❑ Seeps/Springs
❑ Additional Sheets Attached
2009 Surface Water Design Manual
2
Erosion Potential
1!912009
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL.
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
F art 11s DRAINAz -E"DESIGN_LiMli" TIONS
REFERENCE
❑ Core 2 - Offsite Analysis
❑ Sensitive/Critical Areas
❑ SETA
❑ Other
LJ
❑ Additional Sheets Attached
LIMITATION / SITE CONSTRAINT
<T1F�SUN1MiARY.SHEET, . ':
roVide:oneTtMrnrria: .Sheet perth oldDrschar eArea
Threshold Discharge Area:
name or description)
Core Requirements (all 8 apply)
Discharcie at Natural Location
Number of Natural Discharge Locations:
i Offsite Analysis
Level: 1/ 2 1 3 dated:
Flow Control
Level: 1 1 2 1 3 or Exemption Number
incl. facility summaTy sheet
Small Site BMPs
Conveyance System
Spill containment located at:
Erosion and Sediment Control
ESC Site Supervisor:
Contact Phone:
After Flours Phone.
Maintenance and Operation
Responsibility: Private 1 Public
It Private, Maintenance Log Required: Yes / No
Financial Guarantees and
Provided: Yes 1 No
-Liability
Water Quality
Type: Basic / Sens. Lake ! Enhanced Basicm ! Bog
(include facility summary sheet)
or Exemption No.
Landscape Management Plan: Yes / No
Special Requirements_as applicable
Area Specific Drainage
Type: CDA / SDO 1 MDP / SP / LMP / Shared Fac ! None
Re uirements
Name:
FloodplainlFloodway Delineation
Type: Major / Minor / Exemption 1 None
100 -year Base Flood Elevation (or range):
Datum:
Flood Protection Facilities
Describe:
Source Control
Describe landuse.
(comm./industrial landuse)
Describe any structural controls:
2009 Surface Water Design Manual 1/912009
3
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Oil Control High -use Site: Yes 1 No
Treatment BMP:
Maintenance Agreement: Yes / No
with whom?
Other Drainage Structures
Describe
P�rt'73• EROSION ANDSEN357IENTCONTROL.RE6UIRWr_RTS....
MINIMUM ESC REQUIREMENTS
MINIMUM ESC REQUIREMENTS
DURING CONSTRUCTION
❑ Detention
❑ Infiltration
❑ Regional Facility
❑ Shared Facility
❑ Flow Control
BMPs
LJ Other
AFTER CONSTRUCTION
❑ Clearing Limits
❑ Stabilize Exposed Surfaces
❑ Cover Measures
❑ Remove and Restore Temporary ESC Facilities
❑ Perimeter Protection
❑ Clean and Remove All Silt and Debris, Ensure
❑ Traffic Area Stabilization
Operation of Permanent Facilities
❑ Sediment Retention
❑ Flag Limits of SAO and open space
LJSurface Water Collection
preservation areas
❑ Dewatering Control
LJ Other
❑ Dust Control
❑ Flow Control
Part 1'STORM11tlAT R FAC1i 1T DESeRJP!I0N Nbt+e' iiddrfe 1=ap�li Sutxli ariit Sketch :. , . ;
Flow Control Type/Description
Water Quality
Type/Description
❑ Detention
❑ Infiltration
❑ Regional Facility
❑ Shared Facility
❑ Flow Control
BMPs
LJ Other
❑ Biofiltration
❑ Wetpool
❑ Media Filtration
❑ Oil Control
❑ Spill Control
LJFlow Control BMPs
❑ Other
2009 Surface Water Design Manual 1/9/2009
4
KING COUNTY, WASHINGTON, SURFACE WATER DESICN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
.: Part 15 EASEMENTSITRAiTS
Part 16.::. STRUCTURAL ANALYSIS
❑ Drainage Easement
❑ Cast in Place Vault
❑ Covenant
❑ Retaining Wall
❑ Native Growth Protection Covenant
❑ Rockery > 4' High
❑ Tract
❑ Structural on Steep Slope
❑ Other
❑ Other
I :R
..art 17. SIGNATUItE;OF PRt3E1=SS9ONAL''ENGIIVEEf;�,
I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were
incorporated into this worksheet and the attached Technical Information Report. To the best of my
knowledge the information provided here is accurate.
2009 Surface Water Design Manual 1/9/2009
5
VICINITY MAP
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USDA United States
Department of
Agriculture
�0� NRCS
Natural
Resources
Conservation
Service
A product of the stational
Cooperative Soil Survey,
a joint effort of the United
States Department of
Agriculture and other
Federal agencies, State
agencies including the
Agricultural Experiment
Stations, and local
participants
Custom Soil Resource
Report for
King County
Area,
Washington
January 23, 2012
5-1
Preface
Soil surveys contain information that affects land use planning in survey areas. They
highlight soil limitations that affect various land uses and provide information about
the properties of the soils in the survey areas. Soil surveys are designed for many
different users, including farmers, ranchers, foresters, agronomists, urban planners,
community officials, engineers, developers, builders, and home buyers. Also,
conservationists, teachers, students, and specialists in recreation, waste disposal,
and pollution control can use the surveys to help them understand, protect, or enhance
the environment.
Various land use regulations of Federal, State, and local governments may impose
special restrictions on land use or land treatment. Soil surveys identify soil properties
that are used in making various land use or land treatment decisions. The information
is intended to help the land users identify and reduce the effects of soil limitations on
various land uses. The landowner or user is responsible for identifying and complying
with existing laws and regulations.
Although soil survey information can be used for general farm, local, and wider area
planning, onsite investigation is needed to supplement this information in some cases.
Examples include soil quality assessments (http://soils.usda,gov/sqi/) and certain
conservation and engineering applications. For more detailed information, contact
your local USDA Service Center (http:/loffices. sc.egov.usda.govllocatorlapp?
agency=nres) or your NRCS State Soil Scientist (httpa/soils.usda.govlcontacU
state—off ices/).
Great differences in soil properties can occur within short distances. Some soils are
seasonally wet or subject to flooding Some are too unstable to be used as a
foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic
tank absorption fields. A high water table makes a soil poorly suited to basements or
underground installations.
The National Cooperative Soil Survey is a joint effort of the United States Department
of Agriculture and other Federal agencies, State agencies including the Agricultural
Experiment Stations, and local agencies. The Natural Resources Conservation
Service (NRCS) has leadership for the Federal part of the National Cooperative Soil
Survey.
Information about soils is updated periodically. Updated information is available
through the NRCS Soil Data Mart Web site or the NRCS Web Soil Survey. The Soil
Data Mart is the data storage site for the official soil survey information.
The U -S. Department of Agriculture (USDA) prohibits discrimination in all its programs
and activities on the basis of race, color, national origin, age, disability, and where
applicable, sex, marital status, familial status, parental status, religion, sexual
orientation, genetic information, political beliefs, reprisal, or because all or a part of an
individual's income is derived from any public assistance program. (toot all prohibited
bases apply to all programs.) Persons with disabilities who require alternative means
for communication of program information (Braille, large print, audiotape, etc.) should
contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a
complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400
Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272
(voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and
employer.
Contents tt=.
Preface ................. ...........
............ ................ ......... --- ...........................
--J
How Soil Surveys Are Mmde—........................ ---...... ........................ ........... 6
SoilMap ............................... .................... ....... ..... .............. ...............................
Soil Map (Nelson Middle Gchmo)—............. ................................ ..................... 8
Legend --------------------------------------0
Map Unit Legend (Nelson Middle School) ........ —.............................................. 10
Map Unit Descriptions (Nelson Middle SchooU—......... ............ .......... —... 0
King County Area, Washington, .............. ......... .................... ....... ................ 12
AgC—Aldonwoodgravelly sandy loam.Sho1Spercent slopes ...... ............ 2
References............... ----................ -------............ --........................ 4
Haw Soil Surveys Are Made
Soil surveys are made to provide information about the soils and miscellaneous areas
in a specific area. They include a description of the soils and miscellaneous areas and
their location on the landscape and tables that show soil properties and limitations
affecting various uses. Soil scientists observed the steepness, length, and shape of
the slopes; the general pattern of drainage; the kinds of crops and native plants; and
the kinds of bedrock. They observed and described many soil profiles. A soil profile is
the sequence of natural layers, or horizons, in a soil. The profile extends from the
surface down into the unconsolidated material in which the soil formed or from the
surface down to bedrock. The unconsolidated material is devoid of roots and other
living organisms and has not been changed by other biological activity,
Currently, soils are mapped according to the boundaries of major land resource areas
(MLRAs). MLRAs are geographically associated land resource units that share
common characteristics related to physiography, geology, climate, water resources,
soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically
consist of parts of one or more MLRA.
The soils and miscellaneous areas in a survey area occur in an orderly pattern that is
related to the geology, landforms, relief, climate, and natural vegetation of the area.
Each kind of soil and miscellaneous area is associated with a particular kind of
landform or with a segment of the landform. By observing the soils and miscellaneous
areas in the survey area and relating their position to specific segments of the
landform, a soil scientist develops a concept, or model, of how they were formed. Thus,
during mapping, this model enables the soil scientist to predict with a considerable
degree of accuracy the kind of soil or miscellaneous area at a specific location on the
landscape.
Commonly, individual soils on the landscape merge into one another as their
characteristics gradually change. To construct an accurate soil map, however, soil
scientists must determine the boundaries between the soils. They can observe only
a limited number of soil profiles. Nevertheless, these observations, supplemented by
an understanding of the soil -vegetation -landscape relationship, are sufficient to verify
predictions of the kinds of soil in an area and to determine the boundaries.
Soil scientists recorded the characteristics of the soil profiles that they studied. They
noted soil color; texture, size and shape of soil aggregates, kind and amount of rock
fragments, distribution of plant roots, reaction, and other features that enable them to
identify soils. After describing the soils in the survey area and determining their
properties, the soil scientists assigned the soils to taxonomic classes (units).
Taxonomic classes are concepts. Each taxonomic class has a set of soil
characteristics with precisely defined limits. The classes are used as a basis for
comparison to classify soils systematically. Soil taxonomy, the system of taxonomic
classification used in the United States, is based mainly on the kind and character of
soil properties and the arrangement of horizons within the profile. After the soil
scientists classified and named the soils in the survey area, they compared the
Custom Soil Resource Report
individual soils with similar soils in the same taxonomic class in other areas so that
they could confirm data and assemble additional data based on experience and
research.
The objective of soil mapping is not to delineate pure map unit components, the
objective is to separate the landscape into landforms or landform segments that have
similar use and management requirements. Each map unit is defined by a unique
combination of soil components and/or miscellaneous areas in predictable
proportions. Some components may be highly contrasting to the other components of
the map unit. The presence of minor components in a map unit in no way diminishes
the usefulness or accuracy of the data. The delineation of such landforms and
landform segments on the map provides sufficient information for the development of
resource plans. If intensive use of small areas is planned, onsite investigation is
needed to define and locate the soils and miscellaneous areas.
Soil scientists make many field observations in the process of producing a soil map.
The frequency of observation is dependent upon several factors, including scale of
mapping, intensity of mapping, design of reap units, complexity of the landscape, and
experience of the soil scientist. Observations are made to test and refine the soil -
landscape model and predictions and to verify the classification of the soils at specific
locations. Once the soil -landscape model is refined, a significantly smaller number of
measurements of individual soil properties are made and recorded, These
measurements may include field measurements, such as those for color, depth to
bedrock, and texture, and laboratory measurements, such as those for content of
sand, silt, clay, salt, and other components. Properties of each soil typically vary from
one point to another across the landscape.
Observations for map unit components are aggregated to develop ranges of
characteristics for the components. The aggregated values are presented. Direct
measurements do not exist for every property presented for every map unit
component. Values for some properties are estimated from combinations of other
properties.
While a soil survey is in progress, samples of some of the soils in the area generally
are collected for laboratory analyses and for engineering tests. Soil scientists interpret
the data from these analyses and tests as well as the field -observed characteristics
and the soil properties to determine the expected behavior of the soils under different
uses. Interpretations for all of the soils are field tested through observation of the soils
in different uses and under different levels of management. Some interpretations are
modified to fit local conditions, and some new interpretations are developed to meet
local needs. Data are assembled from other sources, such as research information,
production records, and field experience of specialists. For example, data on crop
yields under defined levels of management are assembled from farm records and from
field or plot experiments on the same kinds of soil.
Predictions about soil behavior are based not only on soil properties but also on such
variables as climate and biological activity. Soil conditions are predictable over long
periods of time, but they are not predictable from year to year. For example, soil
scientists can predict with a fairly high degree of accuracy that a given soil will have
a high water table within certain depths in most years, but they cannot predict that a
high water table will always be at a specific level in the soil on a specific date.
After soil scientists located and identified the significant natural bodies of soil in the
survey area, they drew the boundaries of these bodies on aerial photographs and
identified each as a specific map unit. Aerial photographs show trees, buildings, fields,
roads, and rivers, all of which help in locating boundaries accurately.
Soil Map
The soil map section includes the soil map for the defined area of interest, a list of soil
map units on the map and extent of each map unit, and cartographic symbols
displayed on the map. Also presented are various metadata about data used to
produce the map, and a description of each soil map unit.
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Map Unit Legend (Nelson Middle School)
147np:Counly.11rea, Washingtori.(WA533)'.
-JAap unit Symbol; #ilap link NameAcrss in AOI Percent of ASI.'
AgC Alderwood gravelly sandy loam, 6 to 15 7.7 1 Q0 0%
i percent slopes
Totals for Area of Interest I 7.7 100.0%
Map unit Descriptions (Nelson Middle
School)
The map units delineated on the detailed soil maps in a soil survey represent the soils
or miscellaneous areas in the survey area. The map unit descriptions, along with the
maps, can be used to determine the composition and properties of a unit.
A map unit delineation on a soil map represents an area dominated by one or more
major kinds of soil or miscellaneous areas. A map unit is identified and named
according to the taxonomic classification of the dominant soils. Within a taxonomic
class there are precisely defined limits for the properties of the soils. On the landscape,
however, the soils are natural phenomena, and they have the characteristic variability
of all natural phenomena. Thus, the range of some observed properties may extend
beyond the limits defined for a taxonomic class, Areas of soils of a single taxonomic
class rarely, if ever, can be mapped without including areas of other taxonomic
classes. Consequently, every map unit is made up of the soils or miscellaneous areas
for which it is named and some minor components that belong to taxonomic classes
other than those of the major soils.
Most minor soils have properties similar to those of the dominant soil or soils in the
map unit, and thus they do not affect use and management. These are called
noncontrasting, or similar, components. They may or may not be mentioned in a
particular map unit description. Other minor components, however, have properties
and behavioral characteristics divergent enough to affect use or to require different
management. These are called contrasting, or dissimilar, components, They generally
are in small areas and could not be mapped separately because of the scale used.
Some small areas of strongly contrasting soils or miscellaneous areas are identified
by a special symbol on the maps. If included in the database for a given area, the
contrasting minor components are identified in the map unit descriptions along with
some characteristics of each. A few areas of minor components may not have been
observed, and consequently they are not mentioned in the descriptions, especially
where the pattern was so complex that it was impractical to make enough observations
to identify all the soils and miscellaneous areas on the landscape.
The presence of minor components in a map unit in noway diminishes the usefulness
or accuracy of the data. The objective of mapping is not to delineate pure taxonomic
classes but rather to separate the landscape into landforms or landform segments that
have similar use and management requirements. The delineation of such segments
on the map provides sufficient information for the development of resource plans. If
10
Custom Soil Resource Report
intensive use of small areas is planned, however, onsite investigation is needed to
define and locate the soils and miscellaneous areas.
An identifying symbol precedes the map unit name in the map unit descriptions. Each
description includes general facts about the unit and gives important soil properties
and qualities.
Soils that have profiles that are almost alike make up a soil series. Except for
differences in texture of the surface layer, all the soils of a series have major horizons
that are similar in composition, thickness, and arrangement.
Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity,
degree of erosion, and other characteristics that affect their use. On the basis of such
differences, a soil series is divided into soil phases. Most of the areas shown on the
detailed soil maps are phases of soil series. The name of a soil phase commonly
indicates a feature that affects use or management. For example, Alpha silt loam, 0
to 2 percent slopes, is a phase of the Alpha series.
Some map units are made up of two or more major soils or miscellaneous areas.
These map units are complexes, associations, or undifferentiated groups.
A complex consists of two or more soils or miscellaneous areas in such an intricate
pattern or in such small areas that they cannot be shown separately on the maps. The
pattern and proportion of the soils or miscellaneous areas are somewhat similar in all
areas. Alpha -Beta complex, 0 to 6 percent slopes, is an example.
An association is made up of two or more geographically associated soils or
miscellaneous areas that are shown as one unit on the maps. Because of present or
anticipated uses of the map units in the survey area, it was not considered practical
or necessary to map the soils or miscellaneous areas separately_ The pattern and
relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha -
Beta association, 0 to 2 percent slopes, is an example.
An undifferentiated group is made up of two or more soils or miscellaneous areas that
could be mapped individually but are mapped as one unit because similar
interpretations can be made for use and management. The pattern and proportion of
the soils or miscellaneous areas in a mapped area are not uniform. An area can be
made up of only one of the major soils or miscellaneous areas, or it can be made up
of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example.
Some surveys include miscellaneous areas. Such areas have little or no soil material
and support little or no vegetation. Rock outcrop is an example.
11
Custom Soil Resource Report
!Ging County Area, Washington
AgCAlderwood gravelly sandy loam, 6 to 16 percent slopes
Map knit 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: 180 to 220 days
Map Unit Composition
Atderwood and similar soils: 95 percent
Minor components: 5 percent
Description of Alderwood
Setting
Landform: Moraines, till plains
Parent material. Basal till with some volcanic ash
Properties and qualities
Slope.- 6 to 15 percent
Depth to restrictive feature: 24 to 40 inches to dense 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
Frequency of flooding. None
Frequency of ponding: None
Available water capacity: Very low (about 2.5 inches)
Interpretive groups
Land capability (nonirrigated): 4s
Typical profile
0 to 12 inches: Gravelly sandy loam
12 to 27 inches: Very gravelly sandy loam
27 to 60 inches: Very gravelly sandy loam
Minor Components
Norma
Percent of map unit: 1 percent
Landform: Depressions
Bellingham
Percent of map unit: 1 percent
Landform Depressions
Seattle
Percent of map unit. 1 percent
Landform: Depressions
Tukwila
Percent of map unit: 1 percent
Landform: Depressions
12
CUStOrn Soii Resource Report
Shalcar
Percent of map unit: 1 percent
Landform: Depressions
13
References
American Association of State Highway and Transportation Officials (AASHTO). 2004.
Standard specifications for transportation materials and methods of sampling and
testing. 24th edition.
American Society for Testing and Materials (ASTM). 2005. Standard classification of
soils for engineering purposes. ASTM Standard D2487-00,
Cowardin, L.M., V. Carter, F.C. Golet, and E.T_ LaRoe, 1979. Classification of
wetlands and deep -water habitats of the United States. U.S. Fish and Wildlife Service
FWSIOBS-79131.
Federal Register. July 13, 1994. Changes in hydric soils of the United States.
Federal Register. September 18, 2002. Hydric soils of the United States.
Hurl, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soils
in the United States.
National Research Council. 1995. Wetlands Characteristics and boundaries.
Soil Survey Division Staff 1993. Soil survey manual. Soil Conservation Service. U.S.
Department of Agriculture Handbook 18. http:l/soils.usda,gov/
Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making
and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service,
U.S. Department of Agriculture Handbook 436. http:l/soils usda.gov/
Soil Survey Staff. 2006. Keys to soil taxonomy. 10th edition. U.S. Department of
Agriculture, Natural Resources Conservation Service. http:l/soils.usda.gov/
Tiner, R.W., Jr. 1985. Wetlands of Delaware U.S. Fish and Wildlife Service and
Delaware Department of Natural Resources and Environmental Control, Wetlands
Section
United States Army Corps of Engineers, Environmental Laboratory. 1987, Corps of
Engineers wetlands delineation manual. Waterways Experiment Station Technical
Report Y-87-1
United States Department of Agriculture, Natural Resources Conservation Service.
National forestry manual. http //soils.usda.gov/
United States Department of Agriculture, Natural Resources Conservation Service.
National range and pasture handbook. http:llwww.giti.nres.usda.govl
United States Department of Agriculture, Natural Resources Conservation Service.
National soil survey handbook, title 430 -VI. http:llsoils.usda govt
United States Department of Agriculture, Natural Resources Conservation Service.
2006. Land resource regions and major land resource areas of the United States, the
Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 295.
http:llsoils.usda.govl
14
Custom Soil Resource Report
United States Department of Agriculture, Soil Conservation Service. 1961. Land
capability classification. U.S. Department of Agriculture Handbook 210.
15
APPENDIX B
Soils Information
Figure 1......... Natural Resource Conservation Service
Data
Figure 2......... City of Renton Soil Survey Map
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APPENDIX C
Downstream Analysis
Figure 1......... Drainage System Map, Upstream Tributary
Area
Figure 2......... Drainage System Map, On -Site
Figure 3......... Drainage System Map, Downstream
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AiPPENDIX D
Summary of Drainage Facilities
Figure 1......... Existing Conditions Drainage Basin Map
Figure 2......... Developed Conditions Drainage Basin Map
Figure 3....n.... Flow Control Calculations
Figure 4...0..... Conveyance System Analysis
Project:
Project Number:
Task:
Date:
Performed By:
Reference:
Design Criteria:
Software Used:
KCRTS OUTPUT
Historic Tributary Area:
Nelsen Middle School Site Improvements
211128.10
Appendix D, Figure 3: Flow Control Pond Calculations
March 2, 2012
Michael R. Norton, P.E.
2009 King County Surface Water Design Manual and City of Renton
Amendments to the Icing County Surface Water Design Manual
Match the flow duration of pre -developed rates for forested (historic) site
conditions over the range of flows extending from 50% of 2 -year up to the full
S0 -year flow.
King County Runoff Time Series (KCRTS)
Historic Flows:
Land Use Summary
FAre.a
Till Forest] 1.42 acres;
Till Pasture! 0.00 acres
Till Grass 53.20 acresi
Outwash Forest 0.00 acresl
Outwash Pasture! 0.00 acres
4
Outwash Grasse 0.00 acres
Wedandl 0.00 acres
Impervious 0.2g.acresi
6.84 acresl
is .
_..... _.. .. i
Scale Factor: 1.00 Hourly Reduced
Time Series. predev
4
Compute. Time Series
Modify User input
File for comported Time Series [.TS.FI
y
�£.vkR3'aRti�t)F".'9.D'S..e'..RwIYHRSR.6kYi�d�F63Af#VtMN +LH TW=M`P:-Wd'M11?FIG'�`T?W6M°VYvTM:WF`.k%AifYW3Y'v16yIGSYe1�.n-
Historic Flows:
Flow Frequency Analysis
Time Series File:predev.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates ---
Flow Rate
Rank
Time of Peak
(CFS)
1
100.00
0.574
4
2/09/01 2:00
0.308
7
1/05/02 16:00
0.711
2
2/27/03 7:00
0.152
8
8/26/04 2:00
0.330
6
1/05/05 8:00
0.597
3
1/18/06 16.00
0.536
5
11/24/06 3:00
1.31
1
1/09/08 6.00
0.231
0.152
Computed Peaks
Developed Tributary Area:
-Flow Frequency Analysis -----
Peaks - - Rank Return Prob
(CFS)
0.00 arse
Period
0.00 acne
1.31
1
100.00
0.990
0.711
2
25.00
0.960
0.597
3
10.00
0.900
0.574
4
5M
0.800
0.536
5
3.00
0.667
0.330
6
2.00
0.500
0.308
7
1.30
0.231
0.152
8
1.10
0.091
1.11
50.00
0.980
Land Use Surryn.
FArea --
Till Forest, 0.00
i
Till Pasture; 0.00
"fill Grass! 5.20
Outwash Forest' 0.00
Oulwash Pasturek
0.00 arse
Outwash Grass!
0.00 acne
WeNand
0.00 acre
ImDervilousi
1.64 acre
r- T"
5.84 acres
Sole Factor, 1.00 Hourly Reduced
Time Series: d?
Compute Time Series
Modify User Input -
F__ -
Developed Flows:
for computed 'nme Series [.TSF)
Flow Frequency Analysis
Time Series File:dev.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates ---
Flow Rate
Rank
Time of Peak
{CFS}
(CFS)
42.00 ft
0.862
4
2/09/01 2:00
0.588
7
1/05/02 16:00
1.06
2
2/27/03 7:00
0.505
8
8/26/04 2:00
0.639
6
10/28/0416:00
0.902
3
1/18/06 16:00
0.836
5
11/24/06 3:00
1.87
1
1/09/08 6:00
2.00
0.500
Computed Peaks
Detention Facility Data:
Type of Facility: Detention Pond
-----Flow Frequency Analysis-------
-- Peaks--
Rank
Return
Prob
(CFS)
42.00 ft
Period
1.87
1
100.00
0.990
1.06
2
25.00
0.960
0.902
3
10.00
0.900
0.862
4
5.00
0.800
0.836
5
3.00
0.667
0.639
6
2.00
0.500
0.588
7
1.30
0.231
0.505
8
1.10
0,091
1,60
50.00
0.980
Side Slope: ...............................
3.00 H:1V
Pond Bottom Length: ..............
42.00 ft
Pond Bottom Width: ...............
42.00 ft
Pond Bottom Area: ..................
1764. sq, ft
Top Area at 1 ft. FB: .................
7056, sq. ft
Effective Storage Depth:..........
6.00 ft
Stage 0 Elevation: ....................
0.00 ft
Storage Volume: .....................
. 22248. cu. ft
Riser Head: ...................
.......... 6.00 ft
Riser Diameter: ........................
18.00 inches
Number of orifices: ..................
2
Full Mead
Pipe
Orifice # Height Diameter Discharge
Diameter
(ft)
(in) (CFS)
(in)
1 0.00
1.75 0.203
2 4.25
2.88 0.297
6.0
Top Notch Weir:
None
Outflow Rating Curve:
None
Stage Elevation
Storage
Discharge
Percolation
Surf Area
(ft) (ft)
(cu. ft) (ac -ft)
(cfs)
(cfs)
(sq. ft)
0,00 0.00
0. 0.000
0,000
0.00
1764.
0.02 0.02
35. 0.001
0.011
0.00
1774,
0.04 0.04
71. 0.002
0.016
0.00
1784,
0.05 0.05
89. 0.002
0.019
0.00
1789,
0.07 0.07
125. 0.003
0.022
0.00
1799.
0.09 0.09
161. 0.004
0.025
0.00
1810.
0.11 0.11
197. 0.005
0.027
OM
1820.
0.13 0.13
234. 0.005
0.030
0,00
1830-
0.15 0.15
270. 0.006
0.032
0,00
1840-
0.25 0.25
457. 0.010
0.041
0.00
1892.
0.35
0.35
649.
0.015
0.049
OM
1945.
0.45
0.45
846.
0.019
0.055
0.00
1998.
055
0.55
1048.
0.024
0.061
0.00
2052.
0.65
0.65
1256
0.029
0.067
0.00
2107.
0.75
0.75
1470.
0.034
0.072
0,00
2162,
0.85
0.85
1689.
0.039
0.076
0.00
2218.
0.95
0.95
1914.
0.044
0.081
0.00
2275.
1.05
1.05
2144.
0.049
0.085
0.00
2333.
1.15
1.15
2380.
0.055
0.089
0.00
2391.
1.25
1.25
2622.
0.060
0.093
0.00
2450,
1.35
1.35
2870.
0.066
0.096
0.00
2510.
1.45
1.45
3124.
0.072
0.100
0.00
2570.
1.55
1.55
3384.
0.078
0.103
0.00
2632.
1.65
1.65
3651.
0.084
0.107
0.00
2694.
1.75
1.75
3923.
0.090
0.110
0.00
2756.
1.85
1.85
4202,
0.096
0.113
0.00
2820,
1.95
1.95
4487.
0.103
0.116
0.00
2884.
2.05
2.05
4779.
0.110
0.119
0.00
2948.
2.15
2.15
5077.
0.117
0.122
0,00
3014.
2.25
2.25
5381.
0.124
0.124
0.00
3080.
2.35
2.35
5693.
0.131
0.127
0.00
3147.
2.45
2.45
6011.
0.138
0.130
0.00
3215.
2.55
2.55
6336.
0.145
0.133
0.00
3283.
2.65
2.65
6668.
0.153
0.135
0.00
3352.
2.75
2.75
7006.
0.161
0.138
0.00
3422.
2.85
2.85
7352.
0.169
0.140
0.00
3493,
2.95
2.95
7705.
0.177
0.143
OM
3564,
3.05
3.05
8065.
0.185
0.145
0,00
3636.
3.15
3.15
8432.
0.194
0.147
0.00
3709.
3.25
3.25
8807.
0,202
0.150
0.00
3782-
3.35
3.35
9189.
0.211
0.152
0.00
3856.
3.45
3.45
9578.
0.220
0.154
0.00
3931.
3.55
3.55
9975.
0.229
0.156
0.00
4007.
3.65
3.65
10379.
0.238
0.159
0.00
4083.
3.75
3.75
10792.
0.248
0.161
0.00
4160.
3.85
3.85
11211.
0.257
0.163
0.00
4238.
3.95
3.95
11639.
0.267
0.165
0.00
4316.
4.05
4.05
12075.
0.277
0.167
0.00
4396,
4.15
4.15
12518.
0.287
0.169
0.00
4476.
4.25
4.25
12970.
0.298
0.171
0.00
4556,
4.28
4.28
13107.
0.301
0.174
0.00
4581.
4.31
4.31
13245.
0.304
0.181
0.00
4605,
4.34
4.34
13383.
0.307
0.192
0.00
4629.
4.37
4.37
13523.
0.310
0.207
0.00
4654.
4.40
4.40
13663.
0.314
0.225
0.00
4679.
4.43
4.43
13803.
0.317
0.248
0,00
4703.
4.46
4.46
13945_
0.320
0.274
0.00
4728.
4.49
4.49
14087.
0.323
0.286
0.00
4753.
4.52
4.52
14230.
0.327
0.293
0.00
4778.
4.62
4.62
14712.
0.338
0.315
0.00
4861.
4.72
4.72
15202_
0.349
0.334
0.00
4945.
4.82
4.82
15701.
0.360
0.352
0.00
5030.
4.92
4.92
16208.
0.372
0.368
0.00
5115.
5.02
5.02
16724_
0.384
1.61 CFS at 8:00 on Jan 9 in Year 8
0.383
0.00
5201.
5.12
5.12
17248.
0.396
0.397
0.00
5288.
5.22
5.22
17782.
0.408
0.411
0.00
5376.
5.32
5.32
18324.
0.421
0.423
0.00
5464.
5.42
5.42
18874.
0.433
0.436
0.00
5553-
5.52
5.52
19434.
0.446
0.448
0.00
5643.
5.62
5.62
20003.
0.459
0.459
0.00
5734.
5.72
5.72
20581_
0.472
0.470
0,00
5825.
5.82
5.82
21168.
0.486
0.481
0.00
5917.
5.92
5.92
21764,
0.500
0.492
0.00
6009,
6.00
6.00
22248,
0.511
0.500
0.00
6084,
6.10
6.10
22861.
0.525
0.972
0.00
6178.
6.20
6.20
23484.
0.539
1.830
0.00
6273.
6.30
6.30
24116.
0.554
2.930
0.00
6368.
6.40
6.40
24757.
0.568
4.230
0.00
6464.
6.50
6.50
25409,
0.583
5.710
0.00
6561.
6.60
6.60
26069,
0.598
7.150
0.00
6659.
6.70
6.70
26740,
0.614
7.690
0.00
6757.
6.80
6.80
27421.
0.629
8.190
0.00
6856.
6.90
6.90
28111.
0.645
8.660
0.00
6956.
7.00
7.00
28812.
0.661
9.100
0.00
7056.
7.10
7.10
29523.
0.678
9.520
0.00
7157.
7.20
7.20
30243.
0.694
9.930
0.00
7259.
7.30
7.30
30974.
0.711
10.320
0,00
7362.
7.40
7,40
31716,
0.728
10.690
0.00
7465.
7.50
7.50
32468.
0.745
11.050
0.00
7569.
7.60
7,60
33230.
0.763
11.400
0.00
7674,
7.70
7.70
34002.
0.781
11.740
0.00
7779.
7.80
7.80
34786.
0J99
12.070
0.00
7885,
7.90
7.90
35579.
0.817
12.390
0.00
7992.
8.00
8.00
36384.
0.835
12.700
0.00
8100.
Hyd
Inflow
Outflow
Peak
Storage
Target
Calc
Stage
Elev
(Cu -Ft)
(Ac -Ft)
1
1.87
1.31
1.61
6.17
6.17
23322.
0.535
2
1.06
******"
0.42
5.28
5.28
18115.
0.416
3
0.84
*******
0.47
5.74
5.74
20721.
0.476
4
0.90
*******
0.46
5.58
5.58
19799.
0.455
5
0.86
*******
0.64
6.03
6.03
22424.
0.515
6
0.51
*******
0.28
4.47
4.47
13978.
0.321
7
0.59
*******
0.15
3.32
3.32
9074_
0.208
8
0.51
*******
0.11
1,71
1.71
3820.
0.088
Route Time Series through Facility
Inflow Time Series File: ................... dev.tsf
Outflow Time Series File: ............... rdout
Inflow/Outflow Analysis:
Peak Inflow Discharge: ...................
1.87 CFS at 6:00 on Jan 9 in Year 8
Peak Outflow Discharge: ................
1.61 CFS at 8:00 on Jan 9 in Year 8
Peak Reservoir Stage: .....................
6.17 Ft
Peak Reservoir Elev:.......................
6.17 Ft
Peak Reservoir Storage: .. .......... -... 23322. Cu -Ft
Flow Duration from
Time Series File:
............
rdout.tsf
New
%Change
Cutoff
Count
Frequency
CDF
Exceedence_Probability
0.48E-02
0.33E-02
CF5
0.248
%
%
%
0.290
0.19E-02
0.009
44884
73.196
73.196
26.804
0.268E+00
0.027
5969
9.734
82.931
17.069
0.171E+00
0-045
3327
5.426
88.356
11.644
0.116E+00
0.063
2271
3.704
92.060
7.940
0.794E-01
0.081
1597
2.604
94.664
5.336
0.534E-01
0.098
1079
1.760
96.424
3.576
0.358E-01
0.116
724
1.181
97.604
2.396
0.240E-01
0.134
517
0.843
98.447
1.553
0.155E-01
0.152
388
0.633
99.080
0.920
0.920E-02
0.170
271
0,442
99.522
0.478
0.478E-02
0.188
68
0.111
99.633
0.357
0.367E-02
0.206
24
0.039
99.672
0.328
0.328E-02
0.223
25
0.041
99.713
0.287
0.287E-02
0.241
14
0.023
99.736
0.264
0.264E-02
0.259
11
0-018
99.754
0.246
0.246E-02
0.277
9
0.015
99.768
0.232
0.232E-02
0.295
17
0.028
99.796
0.204
0.204E-02
0.313
17
0.028
99.824
0.176
0.176E-02
0.331
18
0.029
99.853
0.147
0.147E-02
0.349
11
0.018
99.871
0.129
0.129E-02
0.366
6
0.010
99.881
0.119
0.119E-02
0.384
11
0.018
99-899
0.101
0.101E-02
0.402
12
0.020
99.918
0.082
0.815E-03
0.420
12
0.020
99.938
0.062
0.620E-03
0.438
9
0.015
99.953
0.047
0.473E-03
0.456
10
0.016
99.969
0.031
0.310E-03
0.474
10
0.016
99.985
0.015
0.147E-03
0.491
3
0.005
99.990
0.010
0.978E-04
0.509
2
0.003
99.993
0.007
0.652E-04
0.527
1
0.002
99.995
0.005
0.489E-04
0.545
0
0.000
99.995
0.005
0.489E-04
0.563
0
0.000
99.995
0-005
0.489E-04
0.581
1
0.002
99.997
0.003
0.326E-04
0.599
0
0.000
99.997
0.003
0.326E-04
0.617
1
0.002
99.998
0.002
0.163E-04
0.634
0
0.000
99.998
0.002
0.163E-04
Duration Comparison Anaylsis:
Base File: predev.tsf
New File: rdout-tsf
Cutoff Units: Discharge in CF5
Check of Tolerance
Probability
---------Fraction of Time ---------
Cutoff
Base
New
%Change
0.164 f
0.68E-02
0.64E-02
-6.7
0.206 j
0.48E-02
0.33E-02
-32.7
0.248
0.31E-02
0-26E-02
-16.4
0.290
0.19E-02
0-22E-02
15.5
Check of Tolerance
Probability
Base
New
%Change
0.68E-02
0.164
0.162
-1.2
0.48E-02
0.206
0.170
-17.6
0.31E-02
0.248
0.213
-14.0
0.19E-02
0.290
0.304
5.0
0.332
0.13E-02
0.15E-02 16.9
0.13E-02
0.332
0,353
6.3
0.374E
0-85E-03
0.11E-02 30.8
0.85E-03
0.374
0.401
7.3
0.416
0.64E-03
0.70E-03 10.3
0.64E-03
0.416
0.419
0.8
0.458
0.36E-03
0.29E-03 -18.2
0.36E-03
0.458
0.451
-1.6
0.500
0.21E-03
0.82E-04 -61.5
0.21E-03
0.500
0.468
-6,4
0.542
0,15E-03
0.49E-04 -66.7 i
0.15E-03
0.542
0,480
-11.4
0.584
0.49E-04
0,33E-04 -33.3
0.49E-04
0.584
0.565
-3.1
0.626
033E-04
0.16E-04 -50.0
0.33E-04
0.626
0.605
-3.4
0.668
0.16E-04
0.00E+00 -100.0
0-16E-04
0.668
0-635
-4.9
0.710
0,16E-04
0.00E+00 -100.0
0.16E-04
0.710
0.635
-10.5
Maximum positive excursion = 0-033 cfs ( 9.6%) F <10% (OK)
occurring at 0.342 cfs an the Base Data:predev.tsf
and at 0.375 cfs on the New Data:rdout.tsf
Maximum negative excursion = 0.046 cfs (-21-0%)
occurring at 0.219 cfs on the Base Data:predev.tsf
and at 0.173 cfs on the New Data:rdout.tsf
APPENDIX E
Geotechnical Report
Associated Fath Sciences, Ince
DN E NJ W] 46
C6�W ra&n Over 25 Yearn a f'yer ce
May 16, 2011
Project No, KE1 10083A
Renton School District
c/o Greene-Gasaway. PLLC
P.O. Box 4158
Federal Way, Washington 98063
Attention: Mr. Sam Rosendahl
Subject. Subsurface Exploration, Geologic Hazards, and
Preliminary Geotechnical Engineering Report
Nelsen Middle School Improvements
2403 Jones Avenue South
Renton, Washington
Dear Mr. Rosendahl:
We are pleased to present these copies of our preliminary report for the referenced project.
This report summarizes the results of our subsurface exploration, geologic hazards, and
geotechnical engineering studies, and offers preliminary recommendations for the design and
development of the proposed project_ Our report is preliminary since project plans were under
development at the tirne this report was written. We should be allowed to review the
recommendations presented in this report and modify diem, if needed, once final project plans
have been formulated.
We [lave enjoyed working with you on this study and are confident that the recominexidations
presented in this report will aid in the successful completion of your project. If you should
have any questions regarding this report or if we can be of additional help to you, please do
not hesitate to call.
Sincerely,
ASSOCIATED EARTH ,SCIENCES, INC.
Kirkland, Washington
Kurt D. Merriman, P. E.
Principal Engineer
KDMlibf1d - KEI10083A3 - Projecis1201100831KDWP
Kirkland 10 Everett N Tacoma
425 - 8 27-7701 425-259-0522 253-722-2992
www.aesgeo.com
GeotechnicaCEngineering
Water Resourees
` 7,zviron.merttaC.Assessjne?its
and Remediation
SustairtaGCe Developinent Services
geologic -Assessments
Associated Earth Sciences, Inc.
Serving the Tactfic Worthwest Since 1-981
Subsurface Exploration, Geologic Hazards, and
Preliminary Geotechnical Engineering Report
NELSEN MIDDLE SCHOOL
IMPROVEMENTS
Renton, Washington
Prepared for
Renton School District
clo Greene-Oasaway, PLLC
Project No. KE110083A
May 16, 2011
SUBSURFACE EXPLORATION, GEOLOGIC HAZARDS, ANY
PRELIMINARY GEOTECHNICAL ENGINEERING REPORT
NELSEN MIDDLE SCHOOL IMPROVEVIEN'TS
Renton, Washington
Prepared for:
Renton School District
c/o Greene-Gasaway, PLLC
P.O. Box 4158
Federal Way, Washington 98063
Prepared by:
Associated Earth Sciences, Inc.
911 5"' Avenue, Suite 100
Kirkland, Washington 98033
425-827-7701
Fax; 4.25-827-5424
May 16, 2011
Project No. KE110083A
, 1id-.k1il�?ce F):piuj...ion ('e�x 'ic HOZ,7? ds, and
�'815C77'V�Iida"'t, s(li0oi 11T 7;pVP112E'I:CC pl'�2i7?:L7121�' cCal Report
Renton. ih%;shu;P!o�� Prolec; and Srie Conditiotls
I. PROJECT AND SI'Z'E CONDITIONS
1.0 INTRODUCTION
This report presents the results of our subsurface exploration, geologic hazards, and
Preliminary geoteclaiical engineering studies for the proposed improvements at Nelsen Middle
School. The location of the site is presented on the "Vicinity Map," Figure 1. The
approximate locations of exploration borings cotnpleted for this study are shown on the "Site
and Exploration Plan," Figure 2. Logs of the subsurface explorations completed for this study
and copies of laboratory testing results are included in the Appendix.
1.) Purpose and Scope
The purpose of this study was to provide geotechnical engineering recommendations to be
utilized in the preliminary design of the project. This study included a review of selected
available geologic literature, advancing 13 exploration borings, and performing geologic
studies to assess the type, thickness, distribution, and physical properties of the subsurface
sediments and shallow ground water. Grain size analysis and moisture content laboratory tests
were completed on selected soil samples recovered from our exploration borings.
Geotechnical engineering studies were completed to establish preliminary recommendations for
the type of' suitable foundations and floors, allowable foundation soil bearing pressure,
anticipated foundation and floor settlement, permeable and conventional pavement
recommendations, and drainage considerations. This report summarizes our fieldwork and
offers preliminary recommendations based on our present understanding of the project. We
recommend that we be allowed to review the recommendations presented in this report and
revise them, if needed, when a project design has been finalized.
1.2 Authorization
Authorization to proceed with this study was granted by the Renton School District by means
of Purchase Order #2011000115. Our work was completed in general accordance with our
scope of work and cost proposal, dated March 21, 2011. This report has been prepared for the
exclusive use of the Renton School District (RSD); and its agents, for specific application to
this project. Within the limitations of scope, schedule, and budget, our services have been
performed in accordance with generally accepted geotechnical engineering and engineering
geology practices in effect in this area at the time our report was prepared. No other warranty,
express or implied, is niade.
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,Subsu�face Explorntion, Geologic Hazards, and
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Renton, Wadi roe. PrOjecr rod Site Condirions
?.0 PROJECT AND SITE DESCRIPTION
Project plans were under development at the time this report was prepared. Based on our
discussions with Greene-Gasaway, PLLC, we understand that the project will consist of a
substantial site renovation, with site improvements consisting of replacing some of the existing
paving with permeable asphalt pavement, constructing two new baseball fields and one new
soccer field; and installing a new storm water handling facility. We understand that infiltration
is currently under consideration for the handling of storm water runoff. We anticipate that
new structures and paving can be constructed close to existing grades, with typical cuts and
fills of less than about 5 feet to achieve finished grade.
Our previous work on the site included construction monitoring services in 1999 for building
additions and new pavement areas to the north and west of the main building. Based on this
previous work and our review of the published geologic map, we anticipated that the site is
underlain by fill overlying glacially consolidated Vashon till deposits.
The existing school includes a main building on the southeast part of the site, with athletic
facilities to the north and west, and paved parking areas to the south, northeast, and west of the
main building. Site topography is relatively flat to gently sloping, with sloped grassy "steps"
which lead downward to the north and west to existing sports field areas. The ground surface
continues steeply downward from the subject site, approximately 15 to 20 vertical feet to the
north and roughly 25 vertical feet to the west, to nearby properties. A wooded stream corridor
with areas of ponded water lies to the east.
3.0 SUBSURFACE EXPLOR-ATJON
Our subsurface exploration completed for this project included advancing 13 exploration
borings. The conclusions and recommendations presented in this report are based on the
explorations completed for this study. Additional sources of geotechnical data are discussed in
the `Subsurface Conditions" section of this report. The locations and depths of the
explorations were completed within site and budget constraints.
3.1 Exploration Borings
The exploration borings were completed by advancing hollow -stem auger tools with a track -
mounted drill rig_ During the drilling process, samples were obtained at generally 2.5- to 5 -
foot -depth intervals, The exploration borings were continuously observed and logged by a
representative from our firm. The exploration logs presented in the Appendix are based on the
field logs, drilling action, and inspection of the samples secured,
Disturbed but representative samples were obtained by using the Standard Penetration Test
(SPT) procedure in accordance with American Society for Testing and Materials
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Re,yon, l w,,'!mAto17 Frolect and Site coadilions
(ASTM) -D-1586. This test and sampling method consists of driving a standard 2 -inch outside -
diameter, split -barrel sampler a distance of M inches into the soil with a 140 -pound hammer -
free -falling a distance of 30 inches. The number of blows for each 6 -inch interval is recorded,
and the number of blows required to drive the sampler the final 12 inches is known as the
Standard Penetration Resistance ("N") or Now count. If a total of 50 is recorded within one
6 -inch interval, the blow count is recorded as the number of blows for the corresponding
number of inches of penetration. The resistance, or N -value, provides a measure of the
relative density of granular soils or the relative consistency of cohesive soils; these values are
plotted on the attached exploration boring logs. .
The sainples obtained from the split -barrel sampler were classified in the field and
representative portions placed in watertight containers. The samples were then transported to
our laboratory for further visual classification and laboratory testing, as necessary,
Ohservation Well Installation
An observation well was placed in exploration boring EB -9 at the time of drilling to determine
if a static ground water level was present and to measure its depth. On April 21, 2011, a static
water level was measured at a depth of 33.81 feet.
3.2 Laboratory Tests
Laboratory test results are included in the Appendix. The following laboratory tests were
completed for this project:
Three mechanical grain size analyses by ASTM: D-422 and D-1140
Two percent passing the No. 200 sieve by ASTM: D-1140
Five moisture content tests by ASTM:D-2216
4.0 SUBSURFACE CONDITIONS
Subsurface conditions at the project site were inferred from the field explorations accomplished
for this study, visual reconnaissance of the site, and review of selected applicable geologic
literature. We also reviewed field reports completed by Associated Earth Sciences, Inc.
(AESI) during construction of an earlier renovation of Nelsen Middle School in 1999. Because
of the nature of exploratory work below ground, extrapolation of subsurface conditions
between field explorations is necessary. It should be noted that differing subsurface conditions
MAY sometimes be present due to the random nature of deposition and the alteration of
topography by past grading and/or filling. The nature and extent of any variations between the
field explorations may not become fully evident until construction.
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Subsurface Exploration, Geologic Hazards, aid
Neisen Middle School Inzproveznews Prelirrzirzary GeOICCIMical Digincering Report
Rerzrort, YYnshin ion Project and. Site Conditions
4.1 Stratigraphy
Fill
Existing fill was encountered in all exploration borings except for EB -1, EB -2, and EB -5. The
fill ranged in thickness from 4 to 31 feet within our explorations and consisted of loose to
medium dense silty sand with gravel and scattered organics. Figure 2 shows the depth of fill
encountered at each boring location. Existing fill is not suitable for structural' support.
Existing fili should be removed from below planned structure areas, and should be
recompacted Linder paving and athletic fields, especially if synthetic turf is planned. Existing
fill is discussed in greater detail in the "Site Preparation" section of this report.
Stratified Drift Sediments (undifferentiated)
All of our explorations encountered medium dense to very dense brownish gray silty sand with
gravel and sand lenses and beds, with thick sand beds encountered in exploration borings EB -5
and EB -9. As indicated above and described below, our previous work at the site and our
review of the published geologic snap indicate that the site is expected to be underlain by
glacially -consolidated soils, likely lodgement till; however, the sediments we observed were
not typical of lodgement till sediments. The site sediments were somewhat more sorted and, in
places, more stratified than typical lodgement till sediments, although that is the locally
common sedimentary unit they most closely resemble. Lodgement till typically possesses high-
strength and low -compressibility attributes that are favorable for support of foundations, floor
slabs, and paving, with proper preparation. The site soils are silty and moisture -sensitive. In
the presence of moisture contents above the optimum moisture content for compaction
purposes, the site soils can be easily disturbed by vehicles and earthwork equipment. Careful
management of moisture -sensitive soils, as recommended in this report, will be needed to
reduce the potential for disturbance of wet native soils and costs associated with repairing
disturbed soils.
Weathered Teriiary Bedrock
At the location of exploration boring EB -3, the stratified drift was underlain by a highly
fractured silty sand with gravel, which appeared as "chips" in the sampler. We interpret this
material to be representative of weathered Tertiary bedrock. Due to the relatively weak
induration of the weathered rock, the description of the rock on the attached exploration log is
similar to those used to describe soils. Where encountered, the weathered bedrock extended
beyond the depth explored,
Existing Geotechnical Data by AESI (1999)
We reviewed several construction field reports for work completed on-site i31 1999. Our field
reports addressed observation of bearing soils and compaction testing on shear wall foundations
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Subsrllfitce Ezpinralion, Geologic Hazards, and
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Renton, w01i Projecr and Sire col-Idilions
within several classrooms. We also performed compaction testing on the subgf-ade for new
parking areas. Soils described in these field reports are generally consistent with our current
exploration borings.
Published Geologic Map
We reviewed a published geologic map of the area {Geologic Map of King Couv7ry,
Washington, by Derek B. Booth, Kathy A. Troost, and Aaron P. Wisher; 2OO6). The
referenced map indicates that the site vicinity is characterized primarily by lodgement till at the
ground surface; with small exposures of Tertiary bedrock nearby. It is not unusual to find
localized areas that vary from published regional scale geologic mapping, and that is the case
with the stratified drift described at this site. We recommend that design activities for this
project be based on subsurface materials observed in our on-site explorations
4.2 Hydrology
Ground water seepage was encountered in a thick sand bed in exploration boring EB -9 at the
tune of drilling, and we installed a plastic open -standpipe piezometer in EB -9 to allow
measurement of ground water levels after drilling was completed. Observed ground water
conditions are presented on exploration logs included in the Appendix.
In addition, moist to wet soil was encountered at various depths within the existing fill,
suggesting that perched ground water should be expected throughout the site. Perched ground
water occurs where vertical infiltration of surface ';eater is impeded by lower -permeability soil
units at depth. and water tends to move laterally above the perching layer. If construction
takes place during the summer, we do not anticipate significant dewatering will be necessary.
However, during the winter months, dewatering in the form of pumping and/or trenching may
be necessary to collect seepage from excavations.
Ground water conditions should be expected to vary due to changes in season, precipitation,
on- and off-site land usage, and other factors.
4.3 Infiltration Potential/Permeable Pavement Considerations
Our explorations encountered shallow materials that consisted of fill over stratified drift. The
existing fill at ES -13, located at the proposed permeable pavement area at the west parking lot,
classifies as sandy loam on the United States Department of Agriculture (USDA) textural soil
triangle, Much of the underlying drift is silty, and the drift has been consolidated by glaciers,
which limits its potential for use as an infiltration receptor. Wet soil, suggestive of perched
ground water, was observed to vary in depth, but was often relatively shallow, which can also
be a limiting factor that can be difficult or impossible to overcome. In the areas proposed for
permeable pavement, adequate storage of infiltrating storm water will need to be incorporated
into the pavement sections. We recommend that permeable pavement areas be provided with
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Subsurface Eaplortttion, Geologic Hazards, and
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Renton, Washirrgron Project and Sale Coad.;t omy
either underdrains or a conventional surface water collection system to collect available water
when rainfall exceeds the storage capacity and infiltration capacity of the permeable pavement
system. lit general, we conclude that the potential for storm concentrated water disposal by
means of infiltration is very limited at this site.
As stated above, we installed a monitoring well extending below the fill and into a thick sand
bed at the location of exploration boring EB -9, and measured ground water at 33.81 feet below
the ground surface on April 21, 2011. Grain -size analyses performed on samples taken at 25
and 30 feet in EB -9 suggest that a suitable thickness of receptor soil for a deep
discharge/injection well -type system inay exist above the observed ground water. Our borings
did not verify the lateral extent of the potential storm water receptor, and such verification is
an important component of the viability of the potential receptor. Steep slopes located to the
north and west of the subject site, likely capped with a thick fill zone (as encountered in EB -8
an EB -9), also warrant additional study if a deep infiltration system is considered. Additional
studies to support an infiltration design may also include additional explorations, consultation,
or off-site ground water fate and transport studies, including at the residential property located
at the bottom of the steep slope to the west of the subject site.
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IVe1'se1i Middle School lhzpravOa;evrts Preli�nlinon Georech,ucal Engmeering Report
Rewon, Washugton Geologic llazards r,nd 'Viaga!ion",
II. GEOLOGIC HAZARDS AND MITIGATIONS
The following discussion of potential geologic hazards is based on the geologic, slope, and
ground and surface water conditions, as observed and discussed herein. The discussion will be
]united to slope stability, seismic, and erosion issues. It should be noted that the City of
Renton Sensitive Areas mapping and the King County IMAP website show the site as lying
within a known coal mine hazard area, with the Renton Sensitive Areas reap designating the
coal mine hazard as "moderate." Based on the presence of existing development at and
surrounding the subject site, we anticipate that the requirements for a detailed coal mine hazard
study may be waived, per RMC. 4-3-050(D)(4)(b)(i)(c). We are available to provide a detailed
coal mine hazard assessment for the project, if requested.
5.0 SLOPE HAZARDS AND MITIGATIONS
Existing slopes on the site are moderately inclined and do not lrave visual indications of
instability or unusually intense erasion. The slopes leading downward to the west and north of
the subject site are steep and, based on the exploration borings completed nearby, likely
include loose to medium dense fill material. These off-site slopes appear to be greater than
forty percent, placing them into the "high landslide hazard" category per RMC 4-3-
050(J)(I)(b)(iii). However, these slopes did not show sighs of instability at the tiane of our
exploration. Therefore, in our opinion, the proposed improvements should not negatively
impact the slopes or cause instability of these slopes provided that storm water from the
proposed permeable pavement area is not allowed to discharge over the slope faces. Similarly,
if conventional pavement is used, storm water should not be directed to the steep slope areas.
If a detention pond is planned in the area of these slopes, it will likely be excavated in fill and
will need to be lined to prevent leakage into the slope soils.
6.0 SEISMIC HAZARDS AND MITIGATIONS
The following discussion is a ,general assessment of seismic hazards that is intended to be
useful to the school district in terms of understanding seismic issues, and to the structural
engineer for preliminary structural design. In our opinion, the site does not include areas that
meet the City of Renton definition for Seismic Hazard areas.
Earthquakes occur regularly in the Puget Lowland. The majority of these events are small and
are usually not felt by people. However, large earthquakes do occur, as evidenced by the
1949, 7.2 -magnitude event; the 2001, 6.8 -magnitude event; and the 1965, 6_5 -magnitude
event. The 1949 earthquake appears to have been the largest in this region during recorded
history and was centered in the Olympia area. Evaluation of earthquake return rates indicates
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Sutisursace Expbratior, Geologic HcaZnrds, acrd
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Renton, Woshingg on Geofogic Nczards anct MitiRatialrs
that an earthquake of the magnitude between 5.5 and 6.0 is likely within a given
20 -year period.
Generally, there are four types of potential geologic hazards associated with large seismic
events 1) surficial ground rupture, 2) seismically induced landslides, 3) liquefaction, and
4j ground motion. The potential for each of these hazards to adversely impact the proposed
project is discussed below.
6.1 Surficial Groustd Rupture
Generally, the largest earthquakes that have occurred in the Puget Sound area are sub -crustal
events with epicenters ranging from 50 to 70 kilometers in depth. Earthquakes that are
generated at such depths usually do not result in fault rupture at the ground surface. However
current research indicates that surficial ground rupture is possible in the Seattle Fault Zone.
The Seattle Fault Zone is an area of active research. Our current understanding of this fault
zone is poor, and actively evolving. The site is located approximately 5 miles south of the
currently mapped limits of the Seattle Fault Zone. Due to the fact that flit site lies outside of
the currently understood limits of the Seattle Fault Zone, the risk of damage to the project as a
result of surficial ground rupture is low, in our opinion.
6.2 Seismically Induced Landslides
Existing slopes oil the site are moderately inclined and do not have visual indications of
instability or unusually intense erosion. The slopes leading downward to the west and north of
the subject site are steep and, based on the exploration borings completed nearby, likely
include loose to medium dense fill material. However, these slopes did not show signs of
instability at the time of our exploration. Considering the history of adequate slope stability
performance on-site, and the fact that no new buildings are proposed as part of the project, the
risk to the project from seismically induced landslides is low, in our opinion, Storm water
should be collected and routed away from sloping areas. If a detention pond is planned in the
area of these slopes, it will likely be excavated in fill and will need to be lined to prevent
Ieakage into the slope soils.
6.3 Li uefaction
Liquefaction is a process through which unconsolidated soil loses strength as a result of
vibrations, such as those which occur during a seismic event. During normal conditions, the
weight of the soil is supported by both grain-to-gTain contacts and by the fluid pressure within
the pore spaces of the soil below the water table. Extreme vibratory shaking can disrupt the
grain -to -grain contact, increase the pore pressure, and result in a temporary decrease in soil
shear strength. The soil is said to be liquefied when nearly all of the weight of the soil is
supported by pore pressure alone. Liquefaction can result in deformation of the sediment and
settlement of overlying structures. Areas most susceptible to liquefaction include those areas
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Relaorz, JVCShi17 10+z Creo?agic Hazards nrzrr ,�lui gafions
underlain by non -cohesive silt and sand with low relative densities, accompanied by a shallow,
water table.
The subsurface conditions encountered at the site pose low risk of liquefaction due to relatively
high density and lack of an extensive shallow ground water table. No detailed liquefaction
analysis was completed as part of this study, and none is warranted, in our opinion.
6.4 Ground Motion
It is our opinion that any earthquake damage to the proposed structures, when founded on
suitable bearing strata in accordance with the recommendations contained herein, will be
caused by the intensity and acceleration associated with the event and not any of the above -
discussed impacts. Structural design should follow 2009 IBC standards using Site Class "C"
as defined in Table 1613.5.2. The 2009 IBC seisinic design parameters for short period (Ss)
and I -second period (Si) spectral acceleration values were determined from the latitude and
longitude of the project site using the United States Geological Survey. (USGS) National
Seismic Hazard Mapping Project website (ht ://earth uake.us s. ov/hazma s/), These values
are based on Site Class "B". Based on 2002 data, the USGS website interpolated ground
motions at the project site to be I.399g and 0.6328 for building periods of 0.2 and 1.0
seconds, respectively, with a 2 percent chance of exceedance in 50 years. These values
correspond to site coefficients Fa — 1.00 and F, = 1.322, and a peak ground acceleration of
0.373g. The R,, FV, and peak horizontal acceleration values have been corrected for Site Class
"C" in accordance with the IBC.
7.0 EROSION HAZARDS AND MITIGATIONS
The following discussion addresses Washington State Department of Ecology (Ecology)
erosion control regulations that will be applicable to the project. The subject site does not lie
within an erosion hazard area as mapped in the City of Renton `Erosion Hazards" map. Also,
the site soils are characterized by the Natural Resource Conservation Service as having slight
erosion potential, This characterization translates to a "Low Erosion Hazard" designation by
the City of Renton Municipal Code. However, the site is underlain by silty fill and drift
sediments. Therefore, the erosion potential of the site soils is high, especially within the
sloping areas of the site.
As of October 1, 2008, the Ecology Construction Storm Water General Permit (also known as
the National Pollutant Discharge Elimination System fNPDES] permit) requires weekly
Temporary Erosion and Sedimentation Control (TESL) inspections and turbidity monitoring
for all sites 1 or more acres in size that discharge storm water to surface waters of the state.
Because we anticipate that the proposed project (field improvements) will require disturbance
of more than 1 acre, we anticipate that these inspection and reporting requirements will be
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RE7Zt0r2, YVashingtoli Geologic Hazards and Muigations
triggered. The following recommendations are related to general erosion potential and
mitigation.
The TESL inspections and turbidity monitoring of runoff must be completed by a Certified
Erosion and Sediment Control Lead (CESCL) for the duration of the construction. The weekly
TESC reports do not need to be sent to Ecology, but should be logged into the project Storm
Water Pollution Prevention Plan (SWPPP). Ecology requires a monthly summary report of the
turbidity monitoring results signed by the NPDES permit holder. If the monitored turbidity
equals or exceeds 25 nephelometric turbidity units (NTU) (Ecology benchmark standard), the
project best management practices (BMPs) should be modified to decrease the turbidity of
storm water leaving the site. Changes and upgrades to the BMPs should be documented in the
weekly TESC reports and continued until the weekly turbidity reading is 25 NTU or lower. If
the monitored turbidity exceeds 250 NTU, the results trust be reported to Ecology via phone
within 24 hours and corrective actions should be implemented as soon as possible. Daily
turbidity monitoring is continued until the corrective actions lowers the turbidity to below
25 NTU, or until the discharge stops. This description of the sampling benchmarks and
reporting requirements is a brief summary of the Construction Storm Water General Pert -nit
conditions. The general permit template is available on the internet',
In order to meet the current Ecology requirements, a properly developed, constructed, and
maintained erosion control plan consistent with City of Renton standards and best management
erosion control practices will be required for this project. AESI is available to assist the
project civil engineer in developing site-specific erosion control plans. Based on past
experience, it will be necessary to make adjustments and provide additional measures to the
TESC plan in order to optimize its effectiveness. Ultimately, the success of the TESC plan
depends on a proactive approach to project platnting and contractor implementation and
maintenance.
The most effective erosion control measure is the maintenance of adequate ground cover.
Maintaining cover measures atop disturbed ground provides the greatest reduction to the
potential generation of turbid runoff and sediment transport. During the local wet season
(October I" through March 31"), exposed soil should not retrain uncovered for more than
2 days unless it is actively being worked. Ground -cover measures can include erosion control
matting, plastic sheeting, straw mulch, crushed rock or recycled concrete, or mature
hydroseed.
Surface drainage control measures are also essential for collecting and controlling the site
runoff. Flow paths across slopes should be kept to less than 50 feet in order to reduce the
erosion and sediment transport potential of concentrated flow. Ditch/swale spacing will geed
to be shortened with increasing slope gradient. Ditches and swales that exceed a gradient of
about 7 to 10 percent, depending on their flow length, should have properly constructed check
1 littp://www.ecy.wl.goviprogrants/wq/stormwater/construction/constrtsctionfiDatpel-nlit pd{
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Renton, 1Lr7slarr�y°ri Geologic Hazards and M RgCZ2ons
darns installed to reduce the flow velocity of the runoff and reduce the erosion potential within
the ditch. Flow paths that are required to be constructed on gradients between 10 to 15 percent
should be placed in a riprap-lined Swale with the riprap properly sized for the anticipated flow
conditions. Flow paths constructed on slope gradients steeper than 15 percent should be placed
in a pipe slope drain. AESI is available to assist the project civil engineer in developing a
suitable erosion control plan with proper flow control.
With respect to water quality, having ground cover prior to rain events is one of the most
important and effective means to maintain water quality. Once very fine sediment is suspended
in water, the settling times of the smallest particles are on the order of weeks and months.
Therefore, the typical retention times of sediment traps or ponds will not reduce the turbidity
of highly turbid site runoff to the benchmark turbidity of 25 NTU. Reduction of turbidity from
a construction site is almost entirely a function of cover measures and drainage control that
have been implemented prior to rain events_ Temporary sediment traps and ponds are
necessary to control the release rate of the runoff and to provide a catchment for sand -sized
and larger sail particles, but are very ineffective at reducing the turbidity of the runoff.
Silt fencing should be utilized as buffer protection and not as a flow -control measure. Silt
fencing is meant to be placed parallel with topographic contours to prevent sediment -laden
runoff from leaving a work area or entering a sensitive area. Silt fences should not be placed
to cross contour lines without having separate flow control in front of the silt fence. A
swalelberm combination should be constructed to provide flow control rather than let the
runoff build up behind the silt fence and utilize the silt fence as the flow -control measure.
Runoff flowing in front of a silt fence will cause additional erosion and usually will cause a
failure of the silt fence. Improperly installed silt fencing has the potential to cause a much
larger erosion hazard than if the silt fence was not installed at all. The use of silt fencing
should be limited to protect sensitive areas, and swales should be used to provide flow control.
7.1 Erosion Hazard. Mitigation
To mitigate the erosion hazards and potential for off-site sediment transport, we recommend
the following:
1. Construction activity should be scheduled or phased as much as possible to reduce the
amount of earthwork activity that is performed during the winter months.
2. The winter performance of a site is dependent on a well -conceived plan for control of
site erosion and storm water runoff. It is easier to keep the soil on the ground than to
remove it from storm water. The owner and the design team should include adequate
ground -cover measures, access roads, and staging areas in the project bid to give the
selected contractor a workable site. The selected contractor needs to be prepared to
implement and maintain the required measures to reduce the amount of exposed
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Renton, Wshir71017 Geolo is Hazards and Mitig(7tIOIM
ground. A site maintenance plan should be in place in the event storm water turbidity
measurements are greater than the Ecology standards.
3. TESC measures for a given area to be graded or otherwise worked should be installed
soon after ground clearing. The recommended sequence of construction within a given
area after clearing would be to install sediment traps and/or ponds and establish
perimeter flow control prior to starting mass grading.
4. During the wetter months of the year, or when large storm events are predicted during
the summer months, each work area should be stabilized so that if showers occur, the
work area can receive the rainfall without excessive erosion or sediment transport. The
required measures for an area to be "buttoned -up" will depend on the time of" year and
the duration the area will be left un -worked. During the winter months, areas that are
to be left un -worked for more than 2 days should be mulched or covered with plastic.
During the summer months, stabilization will usually consist of seal -rolling the
subgrade. Such measures will aid in the contractor's ability to get back into a work
area after a storm event. The stabilization process also includes establishing temporary
storm water conveyance channels through work areas to route runoff to the approved
treatment facilities.
5. All disturbed areas should be revegetated as soon as possible. It it is outside of the
growing season, the disturbed areas should be covered with mulch, as recommended in
the erosion control plan. Straw mulch provides a cost-effective cover measure and can
be made wind -resistant with the application of a tackifier after it is placed.
6- Surface runoff and discharge should be controlled during and following development.
Uncontrolled discharge may promote erosion and sediment transport. Under no
circumstances should concentrated discharges be allowed to flow over the top of
steep slopes.
?. Soils that are to be reused around the site should be stored in such a manner as to
reduce erosion from the stockpile. Protective measures may include, but are not
limited to, covering with plastic sheeting, the use of low stockpiles in flat areas, or the
use of silt fences around pile perimeters. During the period between October 15` and
March 315`, these measures are required.
&. nn -site erosion control inspections and turbidity monitoring (if required) should be
performed in accordance with Ecology requirements. Weekly and monthly reporting to
Ecology should be performed on a regularly scheduled basis. A discussion of
temporary erosion control and site runoff monitoring should be part of the weekly
construction team meetings. Temporary and permanent erosion control and drainage
treasures should be adjusted and maintained, as necessary, for the duration of project
construction.
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Renron, Washm ton Geologic Hazards and Mif1'M1iol2s
It is our opinion that with the proper implementation of the TESC plans and by field -adjusting
appropriate mitigation elements (BMPs) throughout construction, as recommended by the
erosion controf ir3spector, the potential adverse impacts from erosion hazards ori the project
may be mitigated.
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,Velsen Middle school 1171provenzews Prebmiliary Geotechnical Engu�eerirzg Report
Renion, 1-Yavl mi io>> Preliminary Design Recommendatims
III. PRELIMINARY DESIGN RECOMMENDATIONS
8.0 INTRODUCTION
Our exploration indicates that, from a geotechnical standpoint, the proposed project is feasible
provided the recommendations contained herein are properly followed. The existing fill soils
are adequate for pavement and new athletic field subgrade support, provided they can be
recompacted to a firm, non -yielding condition and are not highly organic, Existing fill is not
suitable for support of new foundations, structural fill or native glacial deposits are suitable for
support of shallow foundations with proper preparation. The bearing stratum for structures is
highly variable. We should be allowed to review project plans as they develop to provide case-
by-case recommendations for foundation support of new structures, as needed.
The site soils are generally not conducive to infiltration of storm water, as storm water will
tend to perch above the existing soils. If permeable pavement is still being considered for this
project, adequate storage of infiltrating storm water will need to be incorporated into the
pavement sections. In addition, provisions to collect and dispose of the storm water runoff in
excess of the permeable pavement storage and infiltration capacity will be necessary.
9.0 SITE PREPARATION
Site preparation of foundation, playfield, and pavement areas should include removal of all
grass, trees, brush, asphalt, debris, and any other deleterious materials. Any depressions
below planned final grades caused by demolition activities should be backfilled with structural
fill, as discussed under the "Structural Fill" section.
Fill within the existing areas to receive new pavement or athletic field fill may be left in place
provided it is inorganic, and can be compacted to a firm, non -yielding condition. It should be
understood that placing new fill over the existing fill may result in settlement of pavernent or
structures planned for this site requiring periodic maintenance. If settlement -sensitive
improvements, such as synthetic sports fields, concession stands, or bleachers are planned in
areas of existing fill, we should be allowed to offer siniation-specific recommendations. In
such situations, the District must make decisions to balance costs of removing existing fill
versus risks of post -construction settlement. We are available to answer questions during the
decision process. The actual observed in-place depths of fill at the exploration locations are
presented on Figure 2 and the exploration lags in the Appendix. All soils disturbed by
stripping and grubbing operations should be recompacted as described below for structural fill.
Once excavation to subgrade elevation is complete, the resulting surface should be proof -rolled
with a loaded dump truck or other suitable equipment or systematically probed with a
1/2 -inch -diameter steel probe under our observation. Any soft, loose, or yielding areas should
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Ren?o_, 1icshua tvrl Preliminary Desgn Recommendations
be excavated to expose suitable bearing soils. The subgrade should then be compacted to at
least 90 percent of the modified Proctor maximum dry density, as determined by the
ASTM -.D-1557 test procedure, and to a firm; non-vielding condition. Structural fill can then
be placed to achieve desired grades; ",,here needed and approved.
9.1 Temporary Cut Slopes
In our opinion, stable construction slopes should be the responsibility of the contractor and
should be determined during construction. For estimating purposes, however, temporary
unsupported cut slopes can be planned at IHAV (Horizontal: Vertical) or flatter in the glacial
drift deposits and 1.5H: IV in existing fill soils provided they are not saturated. Permanent cut
OF fill slopes should not be steeper than 2H: IV.
Tliese slope angles are for areas where ground water seepage is not encountered, and assume
that surface water is not allowed to flow across the temporary slope faces. If ground or
surface water is present when the temporary excavation slopes are exposed, flatter slope angles
will be required. As is typical with earthwork operations, some sloughing and raveling may
occur, and cut slopes may have to be adjusted in the field. In addition, WISHAIOSHA
regulations should be followed at all times.
9.2 Site Disturbance
Most of the on-site soils contain substantial fine-grained material, which makes them moisture -
sensitive and subject to disturbance when wet. The contractor must use care during site
preparation and excavation operations so that the underlying soils are not softened. If
disturbance occurs, the softened soils should be removed and the area brought to grade wit])
structural fill.
9.3 Anter Construction
Due to the moderate to ]sigh M situ moisture content of most of the site soils as judged in the
field and confirmed through laboratory testing, it will likely be necessary to dry some of the
site soils during favorable dry weather conditions to allow reuse in structural fill applications.
Reuse of excavated site soils in compacted structural fill applications is only acceptable if such
reuse is explicitly allowed by project plans and specifications. If construction takes place in
winter, drying is not expected to be feasible, and we anticipate that some of the glacial drift
soils and existing fill will be unsuitable for structural fill applications. Even during dry
weather, site soils excavated for installation of buried utilities might not be suitable for utility
backfill under; paving or other structures. We recommend budgeting for backfill of buried
utility trenches in structural areas with imported select structural fill. For summer
construction, significant but unavoidable effort may be needed to scarify, aerate, and dry site
soils that are above optimum moisture content to reduce moisture content prior to compaction
in structural fill applications. Care should be taken to seal all earthwork areas during mass
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Rewon, Washington Preliminary Desi r: Recommetdol orrs
grading ai the end of each workday by grading all surfaces to drain and sealing them with a
smooth -drum roller. Stockpiled soils that will be reused in structural fill applications should be
covered whenever rain is possible.
If winter construction is desired and approved by the City, the existing pavement or new
crushed rock fill could be used to provide construction staging areas. The stripped subgrade
for crushed rock staging areas should be observed by the geotechnical engineer and should then
be covered with a geotextile fabric, such as Mirafi 50OX or equivalent. Once the fabric is
placed; we recommend using a crushed rock fill layer at least 10 inches thick in areas where
construction equipment will be used.
10.0 STRUCTURAL. FILL
Structural fill may be necessary to establish desired grades in some areas of the site. All
references to structural fill in this report refer to subgrade preparation, fill type, placement,
and compaction of materials, as discussed in this section. If a percentage of compaction is
specified under another section of this report, the value given in that section should be used,
After stripping, planned excavation, and any required overexcavation have been performed to
the satisfaction of the geotechnical engineer/engineering geologist, the upper 1.2 inches of
exposed ground should be recompacted to 90 percent of ASTM.:D-1557. If the subgrade
contains too much moisture, adequate recompaction may be difficult or impossible to obtain,
and should probably not be attempted. In lieu of recompaction, the area to receive fill should
be blanketed with washed rock or quarry spalls to act as a capillary break between the new fill
and the wet subgrade. Where the exposed ground remains soft and further overexcavation is
impractical, placement of an engineering stabilization fabric may be necessary to prevent
contamination of the free -draining layer by silt migration from below.
After recompaction of the exposed ground is tested and approved, or a free -draining rock
course is laid, structural fill may be placed to attain desired grades. Structural fill is defined as
non-organic soil, acceptable to the geotechnical engineer, placed in maximum 8 -inch loose lifts
with each lift being compacted to 95 percent of ASTM:D-1557. In the case of roadway and
utility trench filling, the backfill should be placed and compacted in accordance with City of
Renton codes and standards. The top of the compacted fill should extend horizontally outward
a minimum distance of 3 feet beyond the locations of the perimeter footings or roadway edges
before sloping down at a maximum angle of 2H: IV.
The contractor should note that any proposed fill soils must be evaluated by AESI prior to their
use in fills. This would require that we have a sample of the material at least 72 hours in
advance to perform a Proctor test and determine its field compaction standard. Soils in which
the amount of fine-grained material (smaller than the No_ 200 sieve) is greater thaai
approximately 5 percent (measured on the minus No. 4 sieve size) should be considered
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Hentall, lY'r sktn�rort Prefulzinary Design Reccmin tid mons
moisture -sensitive. All of the soil types observed on-site are estimated and have been
confirmed by laboratory testing to contain significantly snore than 5 percent fine-grained
material. Use of moisture -sensitive soil in structural fills should be limited to favorable dry
weather and dry subgrade conditions. The on-site soils contain substantial amounts of silt and
are considered highly moisture- and disturbance -sensitive when excavated and used as fill
materials. At the time of our exploration program, soil moisture content tests indicated that
most soils encountered were at moisture conditions very near or above optimum for structural
fill use. We anticipate that most excavated soils will require aeration and drying prior to
compaction in structural fill applications. Reuse of excavated site soils in structural fill
applications is only acceptable if such reuse is specifically allowed by project plans and
specifications.
If till is placed during wet weather or if proper compaction cannot be obtained, a select import
material consisting of a clean, free -draining gravel and/or sand should be used. Free -draining
fill consists of non-organic soil with the amount of fine-grained material Iimlted to 5 percent by
weight when measured on the minus No. 4 sieve fraction and at least 25 percent retained on
the No. 4 sieve.
11.0 FOUNDATIONS
Spread footings may be used for structural support when founded directly on undisturbed
glacial deposits or on structural fill placed above suitable native deposits, as previously
discussed. We recommend that an allowable bearing pressure of 2,500 pounds per square foot
{psf) be used for design }purposes, including both dead and live loads. An increase of one-third
may be used for short-teriri wind or seismic loading. Higher foundation soil bearing pressures
are possible for foundations supported entirely on undisturbed glacial drift deposits; however,
we do not expect that higher bearing pressures will be needed. If higher foundation soil
bearing pressures are needed, we should be allowed to offer situation -specific
recommendations.
Perimeter footings should be buried at least 18 inches into the surrounding soil for frost
protection. However, all footings must penetrate to the prescribed bearing stratum, and no
footing should be founded in or above organic or loose soils. All footings should have a
minimum width of 18 inches.
It should be noted that the area bound by lines extending downward at 1H:1V from any footing
must not intersect another footing or intersect a filled area that has not been compacted to at
least 95 percent of ASTM:D-1.557. In addition, a I.5H:1V lime extending down from any
tooting must not daylight because sloughing or raveling may eventually undermine the footing.
Thus, footings should not be placed near the edge of steps or cuts in the bearing soils.
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Renran, wasliinglon 1'i elinzinary' Design Recommendaitons
Anticipated settlement of footings founded as described above should be on the order of 3/ inch
or less. However, disturbed soil not removed from footing excavations prior to footing
placement could result in increased settlements. All footing areas should be inspected by AESI
prior to placing concrete to verify that the design bearing capacity of the soils has been attained
and that construction conforms to the recommendations contained in this report. Such
inspections inay be required by the governing municipality. Perimeter footing drains should be
provided, as discussed under the "Drainage Considerations" section of this report.
If new foundations are plazuied in areas of existing fill, we should be allowed to offer situation -
specific recommendations. Solutions might include removing existing fill, constructing rock -
filled trenches, limited overexcavation and replacement of existing fill, or other alternatives.
11.1 Drainage Considerations
Foundations should be provided with foundation drains placed at the base of footing elevation.
Drains should consist of rigid, perforated, polyvinyl chloride {PVC) pipe surrounded by
washed pea gravel, The drains should be constructed with sufficient gradient to allow gravity
discharge away from the proposed structures. Roof and surface runoff should not discharge
into the footing drain system, but should be handled by a separate, rigid, tightline drain. In
planning, exterior grades adjacent to walls should be sloped downward away from the
proposed structures to achieve surface drainage.
12.4 FLOOR SUPPORT
Floor slabs can be supported ou suitable native sediinents, or on structural fill placed above
suitable native sediments. Floor slabs should be cast atop a minizriurn of 4 inches of clean,
washed, crushed rock (such as '/s -inch "chip") or pea gravel to act as a capillary break. Areas
of subgrade that are disturbed (loosened) during construction should be compacted to a non -
yielding condition prior to placement of capillary break material. Floor slabs should also be
protected from dampness by an impervious moisture barrier at least 10 mils thick. The
moisture barrier should be placed between the capillary break material and the concrete slab,
13.0 FOUNDATION WALLS
All backfill behind foundation walls or around foundation units should be placed as per our
recorninendations for structural fill and as described in this section of the report. Horizontally
backfilled walls, which are free to yield laterally at least 0.1 percent of their height, may be
designed using an equivalent fluid equal to 35 pounds per cubic foot (pcf). Fully restrained,
horizontally backfilled, rigid walls that cannot yield should be designed for an equivalent fluid
of 50 pcf. Walls with sloping backfill up to a maximum gradient of 2H: IV should be designed
using an equivalent fluid of 5.5 pcf for yielding conditions or 75 pcf for fully restrained
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lltelserz Middle School Improlvinents Prcunlncvr - Geolechnical l'ng2neerrrzg Repot?
Renton, Wcshington Ptslirzlirzaly Desiglz Recarzltnendaliolzs
conditions. If parking areas are adjacent to walls, a surcharge equivalent to 2 feet of soil
should be added to the wall height in determining lateral design forces.
As required by the 2049 IBC, retaining wall design should include a seisanic surcharge
pressure in addition to the equivalent fluid pressures presented above. Considering the site
soils and the recommended wall backfill materials, we recommend a seismic surcharge
pressure of 8H and 12H psf, where H is the wall height in feet for the "active" and "at -rest"
loading conditions, respectively. The seismic surcharge should be modeled as a rectangular
distribution with the resultant applied at the mid -point of the walls.
The lateral pressures presented above are based on the conditions of a uniform backfill
consisting of excavated cn-site soils, or imported structural fill compacted to 90 percent of
ASTM:D-1557. A higher degree of compaction is not recommended, as this will increase the
pressure acting on the walls. A lower compaction may result in settlement of the slab -on -grade
or other structures supported above the walls. Thus, the compaction level is critical and most
be tested by our firm during placement. Surcharges from adjacent footings or heavy
construction equipment must be added to the above values. Perimeter footing drains should be
provided for all retaining walls, as discussed under the "Drainage Considerations" section of
this report.
It is imperative that proper drainage be provided so that hydrostatic pressures do not develop
against the wails. This would involve installation of a minimum, 1 -foot -wide blanket drain to
within 1 foot of finish grade for the full wall height using imported, washed gravel against
the walls. A prefabricated drainage mat is not a suitable substitute for the gravel blanket drain
unless all backfill against the wall is free -draining.
13.1 Passive Resistance and Friction Factors
Lateral loads can be resisted by friction between the foundation and the natural glacial soils or
supporting structural fill soils, and by passive earth pressure acting on the buried portions of
the foundations. The foundations must be backfilled with structural fill and compacted to at
least 95 percent of the maximum dry density to achieve the passive resistance provided below.
We recommend the following allowable design parameters:
• Passive equivalent fluid = 250 pcf
0 Coefficient of friction = 0.30
14.0 ATHLETIC FIELD CONSIDERATIONS
We understand that athletic field improvements, consisting of two new baseball fields and a
new soccer field, are currently proposed as part of tine new improvements project. Existing fill
was encountered within the fields with the deepest fills occurring near the northwest corner of
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the subject site. if this fill can be recompacted to a firm, non -yielding condition, it can be used
to support the new surfacing. It is unknown at this time if the new surfacing will be natural or
synthetic tuff.
Synthetic turf and natural turf fields that incorporate underdrains are settlement -sensitive
structures. Post -construction settlement may render portions of the subdrairn system
ineffective, and may result in field surfaces with visible low spots. Such settlement effects are
difficult and cosily to repair, particularly when synthetic turf is used. Considering the
substantial depth of existing fill below some portions of the site, complete removal of existing
fill is likely not an economically viable alternative. Construction of new settlement -sensitive
fields above existing fill carries risks of post -construction settlement. We are available to
discuss settlement risks and approaches to reduce those risks when project plans have been
formulated. Possible approaches include partial removal and recompaction of existing fill, or
selecting athletic field design approaches that are less settlement-selasitive and easier to re -
level.
34.1 Subsurface Drains (underdrains
If athletic field underdrains are planned, the new underdrain system should consist of
perforated PVC pipes, a minimum of 4 inches in diameter, placed approximately 15 to 20 feet
apart. At this site, it might be appropriate to use steeper gradients than normal or underdrain
system pipes to allow them to maintain flow if higher than normal past -construction settlement
occurs. The pipes should have an invert of at least t2 inches below grade and be fully
enveloped in at least 6 inches of free -draining material, containing less than 3 percent fines.
The diameter of the drainage material should be larger than the size of the perforations in the
drainpipe. The remainder of the drainage trench backfill should consist of free -draining
material, conforming to the 2002 Washington State Department of Transportation (WSDOT)
Standard Specifications for Road, Bridge and Municipal Construction, Section 9-03.12(4)
"Gravel Backfill for Drains," which freely communicates with the field surfacing. We defer to
the athletic field designer for specification of the new fields' surfacing material.
14.2 Subsurface Drain Trenchin
Construction of the subsurface drains will require trenching into the underlying sediments. As
part of this study, borings were advanced within the athletic fields to provide preliminary
information on sediment density and ease of trenching. The fill soils within the athletic fields
are in a loose to medium dense condition and should therefore be backhoe -excavated with
limited difficulty. The underlying natural sediments consist of glacial drift soils, which are in
a dense to very dense condition. The drift will be more difficult to excavate than the overlying
fill soils, particularly where gravels and cobbles are present. Therefore, the contractor should
be prepared to encounter dense to very dense sediments during the construction of the
subsurface drains, and suitable excavation equipment should be utilized to expedite
construction.
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Renton, Lv hir, tor. Preliminary Design Recom vl dations
14.3 1-10ht Pole Foundations
We are unaware at this point if new field lighting will be constructed as pari of the field
improvements. We offer the following recommendations to be used if new light poles are
plaimed.
Compressive Capaciries
We recommend that drilled pier(s) be used for light pole foundations. Where feasible, the
piers should penetrate at Ieast 5 feet into very dense glacial drift soils. For vertical
compressive soil bearing values, we recommend using a unit end -bearing capacity of 5 tons per
square foot (tsf) for glacially consolidated sediments. If light poles must be constructed in
areas of existing fill deeper than light pole foundations, end bearing should be neglected in the
structural design. The allowable end -bearing capacity includes a safety factor of 2.0 or more.
Frictional Resistance
For frictional resistance along the shaft of the drilled pier, acting both in compression and in
uplift, allowable skin friction values of 1,000 psf in glacially consolidated sediments, and
250 psf in fill soils are recommended. It is also recommended that frictional resistance be
neglected in the uppermost 2 feet below the ground surface. The allowable skin friction value
includes a safety factor of at least 2.0.
Lareral Capacities
For design against lateral forces on the drilled pier, two methods are typically used. The
parameter used to select the most appropriate design inethod is the length to pier stiffness
factor ratio LIT, where "L" is the pier length in inches and "T" is the relative stiffness factor.
The relative stiffness factor for the pier (T) should be computed by:
T - El
n t,
where: E = modulus of elasticity (pounds per square inch [psi])
1 = moment of inertia (in')
ni, — constant of horizontal subgrade reaction (pounds per cubic inch [pct'])
The factors "E" and "I" are governed by the internal material strength characteristics of the
pier. Representative values of "n," for the soil observed on this site are presented
subsequently. Piers with a LJT ratio of less than 3 may be assumed to be relatively rigid and
act as a pole. The passive pressure approach may be used for this condition. For piers with a
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Renton, Washilitort Preiiminmy Design Recommendations
L/T ratio greater than 3, the modulus of subgrade reaction method is typically used, Both of
these methods are discussed below.
Modulus of Sub rade Reaction Method
Using this method, the pier is designed to resist lateral loads based on acceptable lateral
deflection limits. For granular soils, the coefficient of horizontal subgrade reaction is
considered to increase linearly with depth along the pier. The expression for the soil modulus
"K,," is Kf, = (ni)(XB), where "n," is the coefficient of modulus variation, "X" is the depth
below the ground surface, and "B" is the pier diameter. We recommend using the value for
the coefficient of modulus variation (m) of 150 pci for very dense glacial soils and 30 pci for
existing fill soils.
Passive Pressure Method
Lateral loads on the shallow foundation caused by seismic or transient loading conditions may
be resisted by passive soil pressure against the side of the foundation An allowable passive
earth pressure of 350 pounds per cubic foot (pcf), expressed as an equivalent fluid unit weight,
may be used for that portion of the foundation embedded within dense to very dense native
drift. Below a depth of 2 feet in existing loose to medium dense fill soils, an allowable passive
earth pressure of 200 pcf should be used. The above value only applies to foundation elements
cast "neat" against undisturbed soil. For new structural fill placed around the pier shaft, a
passive earth pressure value of 250 pcf is reco;nmended. All fill must be placed as structural
fill and compacted to at least 95 percent of ASTM:D-1557. Passive resistance within the upper
2 feet should be ignored. However, passive values presented are used assuming an equivalent
triangular fluid pressure distribution over 2 pier diameters beginning at die surface and held at
a constant depth greater than 8 feet. The triangular pressure distribution is truncated above
2 feet.
The presence of large -diameter boulders below the proposed light pole locations is possible.
The owner should be prepared to move the light pole locations if boulders are encountered.
Some drilling contractors can employ specialized drilling equipment to drill through large
boulders, but these methods are often very time consuming and/or expensive.
15.0 PAVEMENT RECOMMENDATIONS
We understand that permeable pavement is being considered for the parking area to the west of
the existing building, and that new conventional pavement may also be included with the
proposed improvements. We have presented recommendations for new conventional pavement
and porous pavement in the sections that follow.
May 16, 2011 ASSOCIATED EARTH SCIENCES, INC.
1PLlrblid - KEI)0033113 - Projects l201100831KEVWP Page 22
5a�i�s �t«ce &rplorct?cin, Geologic Hazoz ds, and
Nelsen iwiddle Sc,+ool Improvements Preiuumary Georecllnical Engineering Report
Ren.orz, WaNhirift01. helunuzmr Design Rec:or moidatioris
15.1 New Conventional Pavement
Conventional pavement for this project would be supported by very dense silty sand (drift),
new structural fill, or recompacted existing fill. These soils should be suitable, with proper
preparation, to allow the use of standard paving sections. Because some of the site soils were
substantially above optimum moisture content at the time of our exploration program, remedial
subgrade preparation might be required below the paving, particularly in areas of existing fill
and silty weathered drift soils. Remedial preparation measures could include removal of some
of the existing site soils below the planned pavement section and restoring the planned
subgrade elevation with select imported structural fill, or aeration and drying of existing soils
prior to compaction of the road subgrades_ It may be necessary to use a separation fabric
between the existing subgrade and new structural fill if fine-grained sediments are exposed
during grading. Preparation of pavement subgrade areas should follow the recommendations
of the "Site Preparation" and "Structural FiLl" sections of this report. The proposed subgrade,
whether it is cut native soils or compacted structural fill, should have a minimum density of 95
percent based on the ASTM:D-1557 test procedure within the upper foot below the pavement
section. Subsequent to compaction or recompaction, the subgrade should be proof -rolled with
a loaded dump truck. Any deflecting areas or soft spots detected during proof -rolling should
be excavated and replaced with properly compacted structural fill. We recommend that the
final determination of how to prepare the pavement subgrades be made at the tune of
construction when weather and field conditions are known.
Upon completion of any recompaction and proof -rolling, a conventional pavement section
consisting of 21/2 inches of asphaltic concrete pavement (ACP) underlain by 4 inches of
11/4 -inch crushed surfacing base course is recommended for car parking areas. A heavier
section consisting of 3 inches of ACP over 6 inches of crushed rock should be used in areas
where bus traffic or other heavy vehicles are expected. The upper 1 inch of 11/4 -inch crushed
rock can be replaced with I'/z inches of 5/8 -inch crushed rock as a leveling course, if desired.
The crushed rock course must be compacted to at least 95 percent of the maximum density,
15.2 Porous Asphalt or Permeable Pavement
Recommendations provided for use in planning and design of the porous pavement proposed as
surfacing in the area of existing parking area west of the existing building focus on providing a
uniform base for support of the porous pavement and allowing maximum infiltration within the
soils beneath the pavement. Approximately 10 feet of fill was encountered over glacially
consolidated drift in exploration boring E13-13 (Figure 2). The density of the fill within 18
inches of the existing parking lot surface is considered to be predominantly medium dense. In
order to provide a uniform base for support of the porous pavement and to allow maximum
infiltration within the soils beneath the pavement, our recommendations include scarification of
the upper 12 inches of soil and all across the exposed parking subgrade.
Moy 16, 20J ASSOCIATED EARTH SCIENCES, INC,A]
IPL.Irbild - MJ6083A3 - Piojen51201100831KElWP Page 23
Subsu+face Exploration, Geologic Hazards, and
Rfelseit rblidd?e 5ehool Intprovenzerus Preilminaiy Geolechnical E)igineering Report
Rel�loyt, Li'aslurt [otz Prelzinu7 + ' Desi r2 Recommendations
The surface of the parking lot should then be graded to drain at a gradient of no more than
I percent toward the present surface water drainage system. Soil removal and surface grading
should be done in such a way as to avoid densification of the exposed soil surface.
Following subgradc preparation, we recommend a passenger car pavement section consisting
of a 3 -inch compacted porous asphalt paving above a 3 -inch thickness of "choker course"
consisting of '/B -inch crushed surfacing top course. Below the choker course, a 12- to 18 -inch -
thick storage layer consisting of 2 -inch permeable ballast (WSDOT 9-03.9[2]) should be placed
above the soil subgrade. The storage layer should be sized for an appropriate amount of storin
water storage assuming a porosity of 0.30. Since a limited amount of the water will infiltrate
the pavement subgrade during large storm events, a drainage system should be established on
the downgradient side(s) of the permeable pavement. The drainage system should include
perforated pipes connected to the site storm drain system. In areas where buses, garbage
trucks, fire trucks, delivery trucks, or other heavy vehicles will be driven or parked, we
recommend a paving section consisting of 6 inches of porous asphalt, 3 inches of choker
course, and 18 inches of storage layer.
Porous asphalt requires regular cleaning to avoid becoming clogged with silt and contaminants
and to maintain the porous properties. We recommend the RSD establish a cleaning schedule
as part of the long-term site maintenance.
16.0 DETENTION POND CONSIDERATIONS
We understand that a detention pond is currently under consideration at the northwest portion
of the subject site as part of the proposed improvements. As part of our exploration program,
we completed three exploration borings at the area of the proposed northwestern detention
pond. In summary, these exploration borings encountered loose to medium dense fill to depths
ranging up to 31 feet, with the deeper fill encountered near to the top of the steep slope leading
downward to the west of the subject site. Since fill sediments were encountered at the likely
elevations of the pond bottom and side slopes, it is our opinion that the pond needs to be
Provided with a liner. A synthetic liner is recommended over a soil liner for this project
because future settlement in the underlying fill may lead to "cracking" and leaks in a soil liner,
which may adversely impact the nearby steep slope. We have also included recommendations
for the use of a cellular confinement system to retain the pond liner cover soil or topsoil
growth medium above the liner, if required. Since the pond will be lined, the existing fill can
remain in place, provided the material is cleaned of debris, moisture -conditioned, and
compacted to a firm and unyielding condition.
A cellular confinement system is recommended to retain liner cover soils and any
recommended topsoil growth medium above the completed liner. A cellular confineinent
system, such as Geoweb® or TerracellO, can be installed for purposes of topsoil containment
and slope erosion control. The proposed system should be approved by the geotechnical
May 16, 2011 ASSOCIATED EARTH SCIENCES, INC.
M,M)MY - ELI 1 0083A a - Projecfi l?01 f00631KE1wP Page 24
Subsurface Es�pioro0on, Gcoiogic Hazards, and
Nelsen A� JXd School Inmrovements Prelinru�aiy Geoieclmir:ai Eltguieci Repo='1
Rentore, Washilr tole Preliminary Desmon Reconune;radars
engineer prior to installation. We recommend the use of 6 -inch -deep cells, Instal] the selected
system in accordance with the manufacturers recommendations. Anchors for the cellular
confinement system should be installed so as to prevent stress points from forming and to
prevent the system from sliding. Anchors should not penetrate the pond liner, The cell
openings should be filled with either a clean pit run sand and gravel as a liner cover or topsoil
specified by the project landscape architect, depending on location in the pond.
interior detention pond slopes should be made at a maximum gradient of 3H: IV or flatter, and
should be consistent with the manufacturer's recommendations for the cellular confinement
system that is selected. Exterior perimeter berm slopes, if required, should be trade at a
maximum gradient of 2H:1V. Perimeter pond berms should have a minimum top width of 6
feet. A base key equal to one-half the berm width and a minimum of 3 feet deep should extend
below the base of the pond berm. Additionally, detention pond berm geometry should
conform to municipal design standards. AESI is available to perforin a geotechnical review of
the final detention pond plans once they are available.
17,0 PROJECT DESIGN AND CONSTRUCTION MONITORING
At the time of this report, site plans, grading plans, structural plans, and construction methods
have not been finalized. We are available to provide additional geotechnical consultation as the
project design develops and possibly changes from that upon which this report is based. We
recommend that AESI perform a geotechnical review of the plans prior to final design
completion. In this way, our earthwork and foundation recommendations may be properly
interpreted and implemented in the design.
We are also available to provide geotechnical engineering and monitoring services during
construction. The integrity of the foundations for buildings and of new pavement depends on
proper site preparation and construction procedures. In addition, engineering decisions may
have to be made in the field in the event that variations in subsurface conditions become
apparent. Construction monitoring services are not part of the current scope of work. If these
services are desired, please let us know, and we will prepare a cost proposal.
May 16, 2011 ASSOCIATED EARTH SCIENCES, INC.
;PLlrhHrl - KEI )0O83A3 - Projecr62011008PK€IWP Page 25
Si&swfoce Exploration, Geologic Hazards, chid
Ne?Selt Middle School IrnPt-ai-ements Preiinninary Geotechnical Engineering Report
Renton, Yi'ashin tori Preiuninary Desi n Reco.ruatendalior"s
We have enjoyed working with you on this study and are confident that these recommendations
will aid in the successful completion of your project. if you should have any questions, or
require further assistance, please do not hesitate to call.
Sincerely,
ASSOCIATED EARTH SCIENCES, INC.
Kirkland., Washington
Jeffrey P. Laub, L.G.: L.E.G.
Prolect Engineering Geologist
Attachments: Figure I: Vicinity Map
Figure 2: Site and Exploration Plan
Appendix: Exploration Logs
Laboratory Test Results
15Un 1,�
Kurt D. Merriman, P.E.
Principal Engineer
May 16, 2011 ASSOCIATED E,4RTH SCIENCES, INC.
)PLAbbe! - HE IX3313 - Pr0lect5120110053WDWP Page 26
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APPENDIX
Classlfications of soils in this report are based on visual field and/or laboratory observations, which include densityiconsistency, moisture condition, grain size, and
plasticity estimates and should not be construed to imply field or laboralory lasting unless presented herein. Visual -manual ariftr laboratory ciassibcafion
methods of ASTM D-2487 and D-2488 were used as an identifrcalion guide for the Unified Soil Classification System.
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EXPLORATION LOG KEY FIGURE Al
0 lid 004_�" 0
0
a
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Well -graded gravel and
Terms Describing Relative Density and Consistency —
aN
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a_ravel with sand, little toi3ensil
SPT12'blawslfoot
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Test Symbols
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Very Dense >50 G =Grain Size
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Silly gravel and silly
Z
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gravel with sand
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Grained Soils
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Medium SliH 4 tc 8 K= Permeability
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AC o
Stift 8 to 15
y
Clayey gravel and
Very Stiff 15 to 30
7 NI
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clayey gravel with sand
Hard >30
Component Definitions
p
C
Weil -graded sand and
6
Descrip5ve Term Size Range and Sieve Number
sW
sand with gravel, little
boulders Larger than 12"
o
LL C
: _
to no fines
Cobbles 3" to 12"
Gravel 3" to No. 4 (4 75 mm)
Poorly sand
U
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and sand with gravel,
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Coarse
Coarse Gravel 3" to 3f4"
Fine Gravel 3/4" Io Nc. 4 (4.75 mm)
m
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little 1D no fines
Sand No. 4 (4.75 mrn) to No 200 (0.075 mm)
Coarse Sand No. 4 (4.75 mm) to No. 10 (2.00 mm)
m
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5iify sand and
silty sand with
Medium Sand NO. 10 (2.00 mm) to No 40 (0.425 mm)
Fine
Sand No. 40 (0.425 mm) to No 200 10.075 mm)
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gravel
Silt and Clay Smaller than Na. 200 (0 075 mm)
U 7
sc
Clayey sand and
(3) Estimated Percentage Moisture Content
@ m
clayey sand will gravel
Percentage by Dry -Absence of moisture,
V)
Component Wei ht dusty, dry to the touch
grace c5 Slightly. Moist - Perceptible
Silt, sandy silt, gravelly sill,
ML
sill With sand or gravel
Few 51010 moisture
Litt}e 15 to 25 Moist - Damp but no visible
in
t
With Non -primary coarse water
oy
Clay of low to medium
constituents 15% Very Mpisl - Water visible but
z
-o m
CL
plasticity; slaty, sandy, ar
Fines content between not free draining
ry
Efrom
gravelly clay, lean Clay
5% and 15% Wet 'Jisible free water, usually
below water table
--
_
Organic clay or sift of low
N
a
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Symbols
2—_—
GL
plasticity
lor
2
_
Sampler
ampportion of 6" Cement grout
15
Type surface seal
Elastic silt, clayey silt, silt
Ali
With miraCEDUS er
2-0'0D Sampler Tye
s bescripfton Benlonile
o
diatomaceous fine sand or
Split Spoon m cel seal
co
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silt
Sampler 3.0" DD S hl S oan Sam ler
p p p - _ ': Filter pack w 1h
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Clay of high plan#;City,
.a
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Sandy or grave clay, fat
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clay with sand or aravel
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Organic clay or silt of
o Porion not recovered End cap
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medium to high
r�if%
pl25ticity
Depth f
Depth
Iz} Percentage by dry weight (4) ground water
of
(SPT) Standard Penetration Test 4
At time of drilling
D-1586)
Peat, muck and other
{ASTM
t3) Q Static water leve; (date)
m
T
C N
o
PT
highly organic soils
In General Accordance wilh
Standard l far Description 151 Combined USCS symbols used #or
O
and Identification of Sails (ASTM D-2486) fines between 5% and 153
Classlfications of soils in this report are based on visual field and/or laboratory observations, which include densityiconsistency, moisture condition, grain size, and
plasticity estimates and should not be construed to imply field or laboralory lasting unless presented herein. Visual -manual ariftr laboratory ciassibcafion
methods of ASTM D-2487 and D-2488 were used as an identifrcalion guide for the Unified Soil Classification System.
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EXPLORATION LOG KEY FIGURE Al
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Ea ti, Sciences, Ii1c.
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-Exploration
17-,7 Projecl Number Exploration Number
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Sheet
KE110083A EB-1
1 of 1
Project
Name
Ne,ISen Middle School
Ground
Surfa—c
Elevation (ft}
Renton WA
Location
Datum
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Boretec/TrK RI
DrilierlFquipment
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37
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S-2
Moist, slightly rust-stained brownish gray, silly fine to medium SAND, with
38
gravel.
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115E
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S-3
Moist. brownish gray, silly fine to medium SAND, with gravel and brown
32
sand pockets.
I
41
541
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10
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f
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Approved
by:
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Grab Sample
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(ATD)
Associated EaOl, Sciences; Inc, Ex 1oratlon Lo
Project Number Exploration Number Sheet
4* l KL110083A E13-2 1 of 1
Project Name Nelsen Middle School Ground Surfane Elevation (fl)
Location Renton, WA — _ Datum �!
DrIler/Equipment Borelec/Track Riq�.__ Date Sart+Finish 4(18111 4LR11,.Lt
Hammer WeighUDrop 1.40#! 30" Hole Diameter (in± E,^
vi U 2 j
L Blows/Foot
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DESCRIPTION 10 2c 30 40
Undifferentiated Stratified Drift i —�-
15 M S-5
I
20
25
Moist, silghtly rust -stained brownish gray, silty fine to meduurn SAND. with
gravel
Moisl, brownish gray, silty fine SAND, with gravel
Moist same.
Moist, brownish oray, silty fine to medium SAND, wiih gravel
isl, brown, fine to medium SAN L), with gravel and trace sill.
tom of exploration boring a1 16 6 feel,
5
11
23
15
33
$7,
123
I28
48
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a
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Associated E. -IT -111 Sciences, Inc. I Exploration Lo
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V- f Project Number Exploration Number
+ (`r� € 11110083A
F-13-3
Project Name Nelsen Kdd#e School
Local"ion Rnton. WA
DrilierrEqulpment Boretec/Track Rig_
Hammer WeighflDrcp 140# / 30"
Sheet
1o`1
Ground Surface Fleval an (ft)
Datum NIA _ _ —
Date Start/Finish
A11 R, 11,4LIR!1 j
Hole Diameter jr'j F^
m 2" GD Split Spoon Sampler (SPT) 0 No Recovery M - Moisture Logged by: JPL
m m 3" 017 Split Spoon Sampler (D & M) lu Ring Sample Q Water Leve! O Approved by:
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S -g
bluish gray, silty SAND, with oravel
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!
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Ali
9
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I
Moist, brownish gray and bluish gray, silty SAND, with gravel
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II
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Mnisl, same
5-8
3
4
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i
0
TIMoisl
to wet brown and gray, silty SAND, with gravei and organics.
S-9
3
3
6
3
i
Undlffereretleted Stratified Dr -1h
I
i
I
15
I
i
Moist, rust -stained gray, silty fine to medium SAND, with gravel
S-10
5
9
A22
13
Weathered TertiaryBedrock
20
Moist, brownish gray, Silty fine SAND. with gravel.
5 1
p!
BOVOM of exploration boring at 20 4 leel
25
gommnlor
E
7—.
fgTV
m 2" GD Split Spoon Sampler (SPT) 0 No Recovery M - Moisture Logged by: JPL
m m 3" 017 Split Spoon Sampler (D & M) lu Ring Sample Q Water Leve! O Approved by:
Grab Sample E SheEby Tube Samp)e 1 Water Level at time of drilling (ATD)
Assorialed Earth Sciences, Inc Exploration Lo
�LL , Project Number Exploralion Number
I.J KE 110083A EB -4 i of 1
Project Name Nelsen Middle School Ground Surface Eievaiian (ft?
Localior _Renton. VVA Daturn N/A.
DrillerrEqu pment `Bor 3lec/Track Rig Date Star -)Finish 4/1 W-1 1 411 Rr'11
Hammer Weight)Drop 140# i 30" Hole Diameter (n) 6,-
E
^
S -t
S-3
20
25 1
E Q J Blows/Foot
DESCRIPTION m 10 20 30 40 O
Fill
Moist, hiown, silky SAND, with gravel and organics
Moist to wel, brown and gray, silty SAND, with gravel and organics
Moisl, ruse -stained gra}, sil!v fine to medium SAND, with gravel.
Undifferentiated Stratified brill
Moist brownish gray, silty fine SAND, with oravei
Moist, with rust staining, same.
Bottom V exploralion boring at 15.5 feel
3 i
i; i X13
EI I
3 '&�
m Sampler Type (ST)
2" OD Split Spoon Sampler (SPT) 0 No Recovery M - Moisture Logged by: JPL
o 3' OD Split Spoon Sampler {D g M) ❑ Ring Sample 4 Water Level (j Approved by:
© Grab Sample Shelby Tube Sample 1 Water Level al time of drilling (ATD)
N
N
Associaled Lartli Sciences, Inc. Exploration La
a Project Number Exploration number �T Sheet
f EKE -11008"A , EB -5I of 1
Project Name Nelsen Middle School Ground Surface Elevafion (tl)
Lcrafion Renton, WA _ Datum NIA _
DrilierrEquipment Boretec/Track RIQ Date StarllFinish X11$119 d11 ft
Hammer WeighUDrop 4p# / 30" �T Hole Diameter (in) 4°
s
m
a
S E
T
°
a�
DESCRIPTION
T
°
u
> o
m
Blows/ Foot
to 20 3o ao
Undifferentrated Stratified Drift
Moist, slightly rust -stained, slity fine to medium SAND. with gravel.
r
S -f
1g�
26
53
27
I
5
I
Moist, brownish gray. silty fine to medium SAND, with gravel and sand
I
�
t
S-2
lenses-
17
23
®q
22
Moist, brownish gray, fine to rnediuM SAND, with gravel.
S-3
9
15
1
A38
22i
t
Moist, same
l
!
S 4
its
28
58
31
i
15
I
Moist, Same
S 5
20
22
50
29I
I
�
Bolfom of expioration baring at 16 5 feet
i
2U
I
kI
I
i
25
I
2" 00 Split Spoon Sampler (SPT) E No Recovery M - Moislure logged by: JPL
3' OD Split Spoon Sampler (D & M) Ring Sample 52 Water Levei (j Approved by:
® Grab Sample Shelby Tube Sample I Water Level at time of drilling (ATD)
Associalcd Ea th Scienceb,
litr.
Exploration Lo
Projectm
Number
Expioratian Number Sheet
--J� ' KE110t783A
El 1 of i
Project rNa-ne
Nelsen Midd4e S0001 _
Ground Surface Eievation (ft)
Lc,-aiion
_Renton- VVA
Datum
Driler%Equipment
Boretec/TrackRig __
DaleStart/Finish 4+1RII1 4118li
Hammer weigt L'Drop
140# i 30" _
_ .�
Hole Diameter (in) 6_
a
a E
a
' Blows/Foot
o
T
n
DESCRIPTION
mi
10 20 30 40
--- Fill
Moist to wet, rust -stained brown,, silty SAND, with gravel.
5 Moist to wet, same with woody debris.
S-2
Wet, same
i S-3
1U - -rMoist, rust -stained brownish gray, silly SAND, with gravel.
S-4
15
rh S-5
26
S -e
Moist to wet, brown and grav, silty SAND, wish gravel and organics.
Moist, same
25Same for 6 inches.
Undifferentiated Stratified Drift
S-7 Moist, slightly rust -stained, silly fine to medium SAND, with gravel
0
$o4tDm of exploration boring at 26.5 feet
N
N �
a
K
7�
8
15
7
2C
31
A'21
A23
0 E
Sampler Type (ST) -
2" DD Split Spoon Sampler (SPT) No Recovery M • Moisture Logged by: JPI_
o 3" OD Split Spoon Sampler (D 8 M) U Ring Sample I Water Level () Approved by:
W © Grab Sample Z Shelby Tube Sample T- Water Level at time of drilling {ATD)
a
Associated Earth Sciences, Inc.
Exploration Log
–1 -,–_I
Project Number
Exploration Number I Sheet
KE110083A
� EB -7 f 1 of 1
Project Name Nelsen Middle School Ground Surface Flevation {ft}
Location Renton, WA Datum N/A
Dri ler/Equipment Boretec/Track Riq _ Date Start+Finish 411R/11 4118/11
Hammer WeightlDrap 140# ! 30" Hole Diameter (in)��—
_
m
_
°
G
a
5
m rDm
•� "3
Blows/Foot
N
S
? o
T'
DE=SCRIPTION
n
r
Q
� 10 20 30 40
Fill
k
E
I
�
Moist, rust -stained brownish gray, silty fine to medium SAND, with gravel.
5f
3
B
12
tt3
I
s
5
Moist to we,,, brown and gray, silty fine to medium SAND, with gravel and
I
S-2
organics.
B
®14
fi
S3
Moist to wet, same,
i
f5
B
t l
Undifferentiated Stratified Drift
Moist, bluish gray, silly fine to medium SAND.
I
S-4
6
13
f
7
I
i
5
Moist to wet, rust -stained bluish gray, fine to medium SAND, with silt and
f
I
8-5
trace gravel.
12
17
&.3
,s
i
Botlom of exploration boring at 16 5 feel
20
i
25
I
JP]Onpn l i yNe to 1).
m 2" OD Split Spoon Sampler (SPT) No Recovery M - Moisture Logged by: JPL
3" OD Split Spoon Sampler (D & M) Ring Sample 7- Water Level O Approved by:
® .arab Sample � Shelby Tube Sample i Water Level at time of drilling (ATD)
Associated Earth 5cienus, lnc. Exploration Log
f� m
r Projecl Nuber ExplDmiion Numbe, Sheet
s KE110083A EB -8 1 of 2
Projecl Name Nelsen (tiliiddie Schn6 Ground Surface Flevalror ift1
Loca€on Renton. WA — Datum Nrq
Driller/Equipment BCreteC/Track RiQ Date SlarL'Finish 4(1 R 11 4; 1
Hammer Weighl]Urop 140# j10" Hole Diameter (in;
r �
7
W io v
Q� — Blows/Foot
5 E S0E °a 3
T cm (n E rjim L
DESCRIPTION
I 10 20 30 40 T�'
I � Fill � F—F-7—
Moist tD wet, brownish gray, silly SAND, with gravel and ❑rganics
MDIM t0 Wet, Settle
Wel, rust -stained brownish gray, Silty fine to medium SAND, with gravel.
Wet, rust -stained brown ana gray, silty fine to medium SAND, with gravel
Moist, bluish gray and brown, silty SAND, with gravel and organics.
MD)sl, slightty ruse -stained brownish gray, 5Pty fine SAND, with gravel.
G
15
15
4 Al
�4
a g
6
3
4
i1
4
p 2D
i
I
12 4
13
12
25 Wet, very litsfe recovery, same I E
S-7 'r 13
16
0
N
Sampler Type (ST).
m 2" OD Split Spoon Sampler (SPT) n No Recovery M - Moisture Logged by: JPL
m fm 3" OD Split Spoon Sampler (D & M) U Ring Sample SZ Waler Level (} Approved by:
4 Grab Sample Shelby Tube Sample water Level at lime of drilling (ATD)
Associated Garth Sciences. Inc. Geologic & Monitorinq Well Construction Loi
r— Pro ecl Number Well Number 5hee1
Prclecl name Nelsen Middle School Location Renton WA
- --
Elevation (Top of Well Casing) Surface Elevating,
Water Level Elevation _ Date StarlFinish 4119111 4;1gj11
Drilling/Equipment BoreteclTrac Riq Acle Diameter din) 6"
Hammer Weighb'Drop
m
7
U �
©
WELL CONSTRUCTIONT
m
! DESCRIPTION
slush monument
Fill
Concrete 0 to 2 feet
5 I Bentonite chips 2 to 26.5 feet
1
I
t' 2 -inch PVC casing 0 to 29 5
feet
20
Moist, brown, silty fine to medium SAND, with gravel and organics.
3 Moist to wet, same.
3
3
f
3 We:, same.
L
2
5
7
5
'6
32
26
Moist to wet, rust -stained brown and gray, silly fire to medium
SAND, with gravel and organics
Moist to wet, with woody debris, same
Undifferentiated Stratified Drift
Wist, slightly rust -stained, silty fine to medium SAND, with gravel.
31Moist, brown, fine to coarse SAND, with gravel and si#t
i 5014"
z� 10/20 silica sand 26.5 to
it 39-5 reef
a
C7
M Sampler Type (ST):
d 2" OD Split Spoon Sampler (SPT) No Recovery M - moisture Logged by: JPL
w Y OD Split Spoon Sampler (D & M) Ring Sample Water Level (4121111 ) Approved by;
Grab Sample Shelby Tube Sample i Water Level a1 time of drilling (ATD)
I Associated Earth Sciestces. 1c Geologic & Monitoring Well Construction LU T
Project Number Well Number Sheet �!
r KE110( EB -9 2 of 2
Protect Name Nelsen Middle Schoal ._._ Location Renton, WA
Elevation (Top of Well ;:asrng) Surface Elevation {R)
Waler Level Elevation _ Date Starl)Finish 411 g ;1 1 4,11.q 1 1
DrillmgrEquipment Boretec/TracK jg Hole Diameter (in) 61, --
Hammer Weight/Drop 140## t 30"
a Ji 3 aE
WELL CONSTRUCTIONY m ` DESCRIPTION
29 Moist, rust stained brownish gray, fine to coarse SAND, with gravel.
501E"
l
f
ch PVC 0.010" Screen
29 5 to 39 5 feet
Q I'
i
35 ;
34 Wet, brownish gray, fine to coarse SAND, with gravel,
f Screw cap
40 I 26 Wel, same
5075"
Bonnterminated af40,9 feet on 4!19/11
i I
i
-45 i
i
I
I
-50
55
a
c�
h Sampler Type (ST):
g © 2" OD Split Spoon Sampler (SPT) No Recovery 1`0 - Moisture Logged by: JPL
3" OD Split Spoon Sampler (D & M) U Ring Sample Water Level (4121111) Approved by:
z Grab Sample Shelby Tube Sample 1 Water Level at time of dri}ling (ATD)
Associated Earth Sciences, Inc. I Exploration LO
R—ED
Y Project Number Expioration Number Sheet
KED 100$3A EB 11 1 of 1
Project Name Nelsen Middle School Ground Surface Elevalion (ft)
Locallan Renton WA Datum Iy1A��—
DrillerrEquipment Boretec/Track Rig_ Date Star/Finish Ail �i111 411 all
Hammer Weight/Drop 140# / 30" Hole Diameter (in)
a
CD
5 CQ`
T
DESCRIPTION
�
_€
v
Slows/Foot
o
m 10 20 30 40
°
Fill
!
F]
I
Moist to wel, Slightly rust -stained brownish gray, silty fine to medium
`
I
S-1
SAND, wish gravel and Irace organics.
A13
!7
5 i
5
I
Moist, same -
S -2
4 9
5
€
Moist, rust -stained brown and gray, silty fine to medium SAND, with gravel
S_3
and trace organics.
Aq
4
�4
1p
i
Undifferentiated Stratified Drift
Moist, rust -stained brownish gray, silty fine to medium SAND, with gravel
S-4
,
2
d AI
I
12
i
I
15
i
Moist, slightly rust -stained brownish gray, silly fine to medium SAND, with
I
I
I
S 5
gravel
8
,32
69
Batlorn ar exploration boring at 15 5 feel
I
20
I
E
E
25
I
'
C
f
l
EE
2" CD Split Spoon Sampler (SPT) No Recovery M - Moisture Logged by: JPL
m m 3" OD Split Spoon Sampler (D & M) U Ring Sample V Water Level {) Approved by:
® Grab Sample Shelby Tube Sample= Water Level at time of driliing (ATD)
Associated Eirth Sciences, tt,r. Exploration Lo
Project Number xpio atio Number Sheet
aE oo83A EB -12 of
P'rOject Name Nelsen Middle _School Ground Surface Ela�,1alion ';Fl) _ �~-
LDralion Rentor. WA Datum R€iA
DriRer`FgApment Boretec/Track Rig HateStartrFinish _4199`11.41]_91 —<<
Hammer Wei ht/Drop 14Q# /a"_ �----
g Hole Diameter (in)
-----
A
a S E E ! a a 3IOWSIFoOi F
GT �
DESCRIPTION 'm 10 20 30 40 �
Fill I
Moist, brawn, silty fine to medium SAND, with gravel and organics.
5-1 I
J
S-2
.1 J �`
I S-5
20 1
25
Moist, same.
Undifferentiated Stratified drift
'hoist, brown, fine to medium SAND, with gravel and siltier zones.
Moist to wet, brownish gray, fine to medium SAND, with trace grave[
Moist, brownish gray, fine to medium SAND, viii silt and t ace gravel.
i
i
Ba0.orn or expioralion boring at 16.5 feet
IB
5!
4
d
A
14
7
7
2D
22
23
I
IB
131
A17
14
I
15
25
23
i
i
N
a
C
a � I
t�
a Sampler Type (ST):
2' OD Split Spoon Sampler (SPT) F] No Recovery M - Moisture
m 3" OD Split Spoon Sampler (D & M) ® Ring Sample 5Z Water Level ()
e ® Grab Sample 0 Shelby Tube Sample i Water Level al time of drilling (A T D)
Logged by- JPL
Approves! by:
Associated L�rth 5crences, Inc.
Exploration Lo
Project Number
Exploration Number
Sheet—�
KE110083A
EB-13
1 of 1
Project Name Nelsen Middle School Ground SUrfaCF Elevation (T.
Location Renton. WA _ Datum
Driller/Equipment B retec/Track Riq Date S1art'Fir sh R11 4!13111 1
_411
Hammer Weightl0rop 140# ! 30" Hole Diameter (in; 4^
N
O
L L
°
4
> '
W
J
Blows/FootC.
E
v
41
5
ro
a
(D LO
Q
E
3F
'r-' P
k
T
DESCRIPTION
"
10 20 30 ao
4 inches asphalt (two layers), 6 inches crushed rock
Fill
Moist, brawn, silty SAND, with gravel and asphalt pieces.
I
5-i
t8;
17:'
d3
Moist, brownish gray, silty fine to medium SAND, with gravel
f S-2
14
a
Al
a
Moist. brownish gray, silty fine SAND, with gravel and trace wood debris.
I
S_3
LIQ
13,
�3
21'
1
Same for 8 inches
I
;
Undifferentiated Stratified Drift
S-4
Moist, rust-stained brownish gray, silly fine to medium SAND, with [race
t8
13
r
gravel
1
19
32
GRAIN SIZE ANALYSIS - MECHANICAL
Date Project Project Na Soil Description
04/2212011 Nelsen Middle School KE110083A Sand little gravel trace silt
Tested By Location EB/EP No125-
Pt.
Depth Intended Use Specification
MS Onsite Eg-9 of moisture wet sample + TareWME
mple Tare 335.62
Wt of moisture dry Sarnpie + Taremple wt + tare 764.83Wt of Tare mple Wt369.2NJt. of moisture Dry Sample mple Ory Wt 338.3Moisture %
S ecitication Re uiremertts
Sieve No. Diam. rnm Wt. Retained °/r, Retained % Passin Minimum Maximum
3 76.1 0.0 100.0
2.5 64 0.0 100.0
2 508 0.0 100.0 -
1.5 381 0.0 100.0 _
1 25.4 0.0 100.0 _
3/4 19 9.43 2.8 97.2
3/8 9.51 3838 11.3 88.7
#4 4.76 79.57 23.5 76.5
#8 2.3E 118.15 34.9 65.1
#10 2 126.97 37.5 62.5
#20 0.85 173.08 51.2 48.8
#40 0.42 247.63 73.2 26.8
#60 0.25 299.6288.6 114 _
4100 0.149 318.66 - 94.2 5.8
#200 0.074 330.1 97.6 2.4
#270 0 053 335.25 99 1 1 0.9 _
US STANDARD SIEVE NOS.
314" NO No 1B NO 40 NO 200
100
so
I
w �
I
I
w 40 I _-
I_
20
I I -
.,..
i00 1Dl 1
0-1
4.01
Gravel Sand Silt and Clay
Curse l=ine Coarse Medium Fine
Grain Size, mm
ASSOCIATED EARTH SCIENCES, INC.
911 5th Ave , Suile 100 Kirkland, WA 98033 425-827-7701 FAX 425-827-5424
CRAW SIZE ANALYSIS m MECHANICAL
Date
Project
Project No.
Soil Description
04122/2011
Nelsen middle Schoo(
KE110083A
Sand with gravel trace silt
Tested By
Location
EB/EP No
IDepth
Intended Use I Specification
M5
Onsite
EB -9
30'
t
VVI of moisture wet sample + Tare
1018.06
Total Sample Tare
521.15
Wtof moisture dry Sample + Tare
986.65
Total Sample wt + tare
986.65
Wt. of Tare
521.15
Tolal Sample Wt
465.5
M. of moisture Dry Sample
465.5
Total Sample Dry Wt
436-1
Moisture °ia
7%
00
100.0
Sieve No.
Diam. mm
Wt. Retained
% Retained
% Passing 4 Minimum v Maximum
3
76.1
0.0
100.0 _
2.5
64
0.0
100.0 - -
2
50.8
00
100.0
1.5
381
0.0
100.0
1
25.4
32.3
7.4
92.6
314
19
32.3
7.4
92.6
318
9.51
77.14
17.7
82.3 _
#4
4.76
130.66
30.0
70.0 _
#8
2.38
198.59
45.5
54.5
410
2
214.6
49.2
50.8
#20
0.85
297.49
68.2
31.8
#40
0.42
363.73
83.4
16.6
#60
0.25
390.84
89.6
10.4
#1100
0,149
407.18
93.4
6.5
#200
0.074
420.17
964
3.6
#270
0.053
425.44
1 97.6
2.4 _
US STANDARD SIEVE NOS.
314' NO 4 NO 16 NO 40
NO ADD
100 , - - ----
- I ,J I
I !
_C 60
40
20
-- ..
1DO
Gravel
Grain Size, mm
A ss O CIA rED Ea R rN SCIENCES, INC.9 r 1 5th Ave Suite 100 Kirkland. WA 98033 425-827,7701 FAx 425.827-5424
Sand
Silt and Clay
Coarse Fme
Coarse
Medium
Fine
Grain Size, mm
A ss O CIA rED Ea R rN SCIENCES, INC.9 r 1 5th Ave Suite 100 Kirkland. WA 98033 425-827,7701 FAx 425.827-5424
Date
Project
Project No.
Soil Description
04/29/2011
Nelsen Middle School
KE110083A
Sand with silt little gravel
Tested By
Location
EB/EP No JDepth
Intended Use/ Specification
M5
Onsite
EB -13 5'
319.3
4Vl. of moisture wet sample + Tare
29463
Total Sample Tare
395.59
Vd1 of moisture dry Sampie + Tare
274.81
Total Sample wt + tare
751
Wt. o1 Tare
913
Total Sample Wt
355.4
Wt. of moisture Dry Sample
17551
Total Sample Dry Wt
319.3
Moisture %
11%
0.0
100.0
I c-tC-k o
Sieve No
Diam. mm
Wt, Retained
% Retained
% Passing Minimum Maximum
3
76.1
0.0
100.0 - -
2-5
64
0.0
100.0
2
50.8
0.0
100.0
1.5
38.1
0.0100.0
1
25.4
0.0 w
100.0 _
3/4
19
13.8
4.3
95.7
318
9.51
2712
8.5
91.5 _
#4
4.76
48.05
15.0
85.0
#8
2.38
6526
20.4
79.6
#10
2
69.22
21-778.3
_
#20
0.85
87.14
27.3
72.7 -
#40
0-42
116.61
37.1
62.9 _
#60
0-25
163.43
51.2
48.8
#100
0.149
195.96
61.4
38.6
#200
0.074
218.37
66.4
31.6 _
#270 1
0.053
226.68
71.0
29.0 _
US STANDARD SIEVE NDS
314" NO 4 NO 16 NO 40 NO 200
i
1pG 10 1 [l 1 n n�
Gravel
Sand
Silt and Clay
Coarse
Fine
Coarse Medium
Fine
Grain Size, mm
ASSOCIATED EARTH SCIENCES, INC.
911 5th Ave., Suite 100 Kirkland, WA 98033 425-827-7701 FAX 425-827-5424
Associated Earth Sciences, Inc.
Percent Passing #200
ASTM D 1140
Date Sampled
Project
Project No.
Soil Description
04/22/2011
Nelsen Middle School
KE110083A
Sand with sift
Tested By
Location
EB/EP NoDepth
74.5
MS
Onsite
298
Actual Dry Weight
513.5
Sample I.D.
EB -1i 2.5'
EB -122.5'
Wet Weight
891 .7
825.5
Dry Weight
827 4
751.0
Water Weight
64.4
74.5
Pan
31 3.)
298
Actual Dry Weight
513.5
452.7
Percent of Water Weight
12.5
16.5
After Wash Weight
66-1 F<
614.1
Percent Passing #200
32.0
30.2
ASSOCIATED EARTH SCIENCES, INC.
911 51h Ave . Suite 100 Kirkland, WA 98033 425.827-7701 FAX 42"27-5424
Associated
Earth Sciences,
Inc.
Moisture Content
ASTM ® 2216
Date Sampled
Project
Project No.
Soil Description
04/22/2011
Nelsen Middle School
KE110083A
Tested By
Location
EB/EP No.
Depth
Various
MS
Onsite
Sample 10
EB -5 2.5'
EB -10 5'
EB -11 2.5'
Wet Weight + Pan
465.4
562.7
361.0
Dry Weight + Pan
4353
521.4
330.5
Weight of Pan
99.3
100.1
101.6
Weight of Moisture
30.1
41.3
30.5
Dry Weight of Soil
336.0
421.3
228.9
% Moisture
9.0
9.8
13.3
Sample ID
EB -11 15'
E8-12 2.5'
Wet Weight+ Pan
495.9
281.5
Dry Weight + Pan
4594
260.6
Weight of Pan
100.8
94.9
Weight of Moisture
36.5
20.8
Dry Weight of Soil
358.6
165.8
% Moisture
10.2
12.6
ASSOCIATED EARTH SCIENCES, INC.
911 51h Ave , Suite 3 DO Kirkkand, WA 98033 425-827-7701 FAX 425-927-5424
APPENDIX F
Bond Quantities, Facility Summaries,
and Declaration of Covenant
Figure 1.......o. Bond Quantities Worksheet
Figure 2......... Flow Control and Water Quality Facility
Summary Sheet
Figure 3......... Declaration of Covenant
APPENDIX G
Operation and Maintenance Manual
APPENDIX H
TESL Analysis and Design
Figure 1......... Temporary Sediment Pond Calculations
Project
Subject 'T. - -
1ti�iihlTc ' ( e
Address --
Date —
Project No.
Phone
Fax #
# Faxed Pages
Dy i 1 s ?,n rz,T .t
f'r r cr.-r�.e' Kl Ws -r
_ J
❑ Page 5, of _
Calculations
❑ Fax
❑ Memorandurn
Meeting Minutes
Telephone Memo
CDCklticir, ��e
V% Ci
7
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!jVF T{^l'..
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Civil Engineers
Structural ,engineers
Landscape Architects
Community Planners
Land Surveyors
Neighbors
❑TACOMA
as 2215 N. 30th 5f.
l Suite 300
Tacoma, WA
98403-3305
253.383.2422
253.383.2572 FAX
❑ SEATTLE
1200 6th Avenue
'- Suite 1620
Seattle, WA
98101-3123
If this does not meet with your understanding, please contact us in writing within seven days. THANK YOU. 206.287.2425
206.267.2429 FAX
Subject .� -
With/To
Address —
Date Qbki - t2- ZZ_
Project INC.
Phone
Fax #
# Faxed Pages
By t." r "
Page o'
Caiculabons
❑ Fax
❑ Memorandum
❑ Meeting Minutes
U Telephone Memo
�..�:oo.=., .,=.�_r-+�,....�,..�.m...y..�..�-._.�....�::��v i�.7` v,�e C. t- f�'.- r� 0. ... �,•�a tic
r �
L= rey
use 14z c) ,v `
�u� _E L
Civil Engineers
Structural Engineers
Landscape Architects
Community Planners
Land Surveyors
Neighbors
QV T
l Yi (CjY'r 4� f 15�".� tCl t'EYf'
❑TACOMA
T
2215 N. 30th St.
nF
Suite 3D0
,r 1 c �C�
Tacoma, WA
98403-3305
253.383.2422
253.383.2572 FAX
0. p
❑ SEATTLE
1200 6th Avenue
Suite 1620
Seattle, WA
98101-3123
If this does Pat meet with your understanding, please contact us in writing within seven days. THANK YOtJ
206.267.2425
206,267.2429 FAX
Landscape Architects
Community Planners
. r Land Surveyors
-_ Neighbors
❑ TACOMA
2215 N. 301h St
Suite 300
Tacoma, WA
98403-3305
253.383.2422
253.383.2572 FAX
❑ SEATTLE
1200 6th Avenue
Suite 1620
Seattle, WA
98101-3123
If this does not meet with your understanding, please contact us in writing within seven days. THANK YOU. 206.267.2425
206.267.2429 FAX
Subjacl
tiro�a ,= ,. ar.-r.
Phone
_� Calculations
❑ Fax
With/To
Fax ti —
- --
fvlemorandum
AMU '04=1❑
Address
_.
4 Faxed Pages
-
❑ Meeting Minutes
Date
; , ... j - l "C,
By 4' E c i r r1 c C �< ` 1;,. r ,
, s , r . ;°_ ❑' Telephone Meirra
Civil Engnreers
��4Y4W r.rs C_•,✓'.}.c-: tee,
G4YG. i';l":'� f•i._G C:°_
"
Structural Engineers
Landscape Architects
Community Planners
. r Land Surveyors
-_ Neighbors
❑ TACOMA
2215 N. 301h St
Suite 300
Tacoma, WA
98403-3305
253.383.2422
253.383.2572 FAX
❑ SEATTLE
1200 6th Avenue
Suite 1620
Seattle, WA
98101-3123
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Project: Nelson Middle School
Project Number: 211128.10
Task: Sediment Pond Calculations - KCRTS output
Date- December 22, 2011
Performed By: Michael R. Norton, P.E.
Flow Frequency Analysis
Time Series File:sed.tsf
ProjectLocation:Sea-Tac
---Annual Peak Flow Rates ---
Flow Rate
Rank
Time of Peak
(CFS)
Prob
(CFS)
0.592
4
2/09/01 12:45
0.372
7
1/06/02 1:00
1.32
3
12/08/02 17:15
0.275
8
8/26/04 1.00
1.37
2
11/17/04 5:00
0.548
5
10/27/0510:45
0.542
6
11/24/06 1:00
2.51
1
1/09/08 6:30
Computed Peaks
0.500
0.372
-----Flow Frequency Analysis -------
Peaks --
Rank
Return
Prob
(CFS)
Period
6 2.51
1 --1-6-0
0-0
1.37
225.00
0.960
3��
0.592
4
5.00
0-800
0.548
5
3.00
0.667
0.542
6
2.00
0.500
0.372
7
1.30
0.231
0.275
8
1.10
0.091
2.13
50.00
0.980
S34 CONTRO] . S"I R1�CTCkDS 1sfcT.�i?DS o,� A 'AL.Y51:5
Riser Overflown
The riomograph in l~igure. 53.4.H may be used to deienmine the head (in feet) above a riser of'give.li
diameter alld for a given flow (usually the 100 -year peak flow for developed conditions).
A
FIGURE 5.3.4.11 RISER INFLOW CURVES
Qweir==9739 DH3r2
Qorirrce=3.7$2 D2H112
Q in cfs, D and H in feet
Slope change occurs at weir -orifice transition
In
2009 Surface Water Design Manual 1/9/2009
5-47
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