HomeMy WebLinkAbout15375 TIR 022817Renton 701 Townhomes DCI 15375
Preliminary Technical Information Report
Renton 701 Townhomes
a
Planned Unit Development
Prepared: October 26, 2016
Revised January 27, 2017
Revised: February 28, 2017
DCI Project: 15375
Duncanson Company, Inc.
145 SW 155th Street, Suite 102
Seattle, Washington 98166
(206) 244-4141
Renton 701 Townhomes DCI 15375
Table Of Contents
1. Project Overview
Figure 1.1 – Technical Information Report Worksheet
Figure 1.2 – Vicinity Map
Figure 1.3 – Basin Map
Figure 1.4 – Soils Survey Map
2. Conditions and Requirements Summary
3. Offsite Analysis
Figure 3.1 – Offsite Analysis Map
4. Flow Control and Water Quality Facility Analysis and Design
Figure 4.1 – Predeveloped Basin Map
Figure 4.2 – Postdeveloped Basin Map
5. Conveyance System Analysis and Design
6. Special Reports and Studies
7. Other Permits
8. CSWPPP Analysis and Design
9. Bond Quantities, Facility Summaries, and Declaration of Covenant
10. Operations and Maintenance Manual
NOTE: Sections 5, 7, 8, 9 and 10 will be completed at the building permit stage.
Renton 701 Townhomes DCI 15375
1. Project Overview
Renton 701 Townhomes DCI 15375
1. Project Overview
The proposed Renton 701 Townhomes project is located at 701-707 Sunset Blvd NE in Renton,
WA (tax lot 311990-0011 & -0010 & -0005). The existing parcel is 39,187 SF or 0.90 acres.
Approximately 1,943 SF of right-of-way will be dedicated along Sunset Boulevard and
improved with minor widening, a planter strip and a sidewalk. The Project Site basin area is
37,244 SF or 0.86 acres. Sunset Boulevard NE will be slightly widened with the addition of
curb, gutter, sidewalk and planter strip. The Sunset Boulevard basin area is approximately
4,882 SF or 0.11 acres. The Site is bordered to the north by apartments, to the east by Sunset
Blvd NE, to the south and west by forested PSE right-of-way. The project will access Sunset
Blvd NE via a new public drive extending west into the site.
The site was previously improved with a small building with a paved and gravel access drive.
Fill was also placed on the property to create a terraced area even with Sunset Boulevard. The
building has been removed; however, the pavement and gravel areas remain in an unmaintained
condition. The remainder of site is covered by trees, blackberry bushes, and grass. The USGS
Soil Map identifies site soils to be Alderwood gravelly sandy loam and Ragnar-Indianola soils
(Figure 1.4). Sanitary sewer exists along the western margin of the site. Water, and storm
drainage systems are located within the Sunset Blvd NE right-of-way. Runoff from the existing
Site generally sheet flows west through the PSE right-of-way and ultimately into the ditch and
pipe system along Interstate 405.
The project includes construction of 15 townhouse units in duplex to 5-plex configurations. A
new internal road and sidewalk will provide access to the units. A storm drain will collect
runoff from the access drive, roof surfaces and some landscape areas. Sewer and water services
and dry utilities will be stubbed to the new units.
The site zoning allows for 75% impervious coverage, or 27,993 SF. The proposed impervious
coverage is 21,111 SF or about 57%.
Included are Figures 1.1 – Technical Information Report Worksheet, 1.2 – Vicinity Map, 1.3 –
Soils Map
Job No. 15375Drawn: HMDScale: NTS
FIGURE 1.2 - Vicinity Map
&LYLO(QJLQHHULQJā6XUYH\LQJā/DQG3ODQQLQJ
145 SW 155th Street, Suite 102
Seattle, Washington 98166
Phone 206.244.4141
Fax 206.244.4455
405
900
Job No. 15375Drawn: HMDScale: NTS
FIGURE 1.3 - Soil Map
&LYLO(QJLQHHULQJā6XUYH\LQJā/DQG3ODQQLQJ
145 SW 155th Street, Suite 102
Seattle, Washington 98166
Phone 206.244.4141
Fax 206.244.4455
Renton 701 Townhomes DCI 15375
2. Conditions and Requirements Summary
Renton 701 Townhomes DCI 15375
2. Preliminary Conditions and Requirements Summary
Following is a discussion of how the Project will conform to the Core and Special
Requirements of the 2009 King County Surface Water Design Manual (KCSWDM) and the
City of Renton Amendments.
King County Surface Water Design Manual Core Requirements:
1. Discharge at the Natural Location
Runoff will continue to flow to the west toward the PSE and I-405 right-of-way. After
detention, runoff will be discharged onto a rock pad. Project runoff will be discharged at a
location where downstream slopes are less than 15% for a distance of at least 50 feet. Some
landscape/vegetated areas will continue to sheet flow to the west.
2. Offsite Analysis
A Level 1 offsite analysis has been performed for this project. See Section 3 for more
information.
3. Flow Control
The Site is within Renton’s Peak Rate Flow Control Standard area. A detentions tank is
proposed to control the peak discharge rates to match the existing conditions for the 2-, 10-,
and 100-year storm events. Onsite stormwater management BMPs are proposed in the form
of Permeable Pavers. See Section 4 for more information.
4. Conveyance System
Conveyance will consist of roof drain collectors and 12-inch pipes. Renton’s conveyance
standard is 6 inches of freeboard at the 25-year storm event. Detailed analysis of the
conveyance system will be prepared at the final engineering/building permit stage.
5. Erosion and Sediment Control
Erosion and sediment control issues and plans will be addressed at the final engineering
stage.
6. Maintenance and Operations
The property owners will be responsible for maintenance of the individual detention system
and water quality facility.
7. Financial Guarantees and Liability
The project owner will provide financial guarantees and liability insurance for construction
of the improvements.
8. Water Quality
Basic Water Quality treatment will be provided in the form of a Stormfilter. The project is
attached single-family, which could be interpreted as multi-family. However, a leachable
metal restrictive covenant will be recorded, so that the Project will meet Exception #4 of the
Enhanced Basic Water Quality requirement. A nominal amount of New PGIS (1,670 SF)
associated with the frontage improvements will remain untreated.
Renton 701 Townhomes DCI 15375
King County Surface Water Design Manual Special Requirements:
(w/City of Renton Amendment)
1. Other Adopted Area-Specific Requirements
No Area-Specific Requirements have been identified.
2. Flood Hazard Area Delineation
This site does not contain and is not adjacent to a flood hazard area; therefore, this
requirement does not apply.
3. Flood Protection Facilities
This project does not rely on and does not propose to modify or construct a flood protection
facility; therefore, this requirement does not apply.
4. Source Control
A detailed Construction Stormwater Pollution Prevention Plan (CSWPPP), including
appropriate source controls will be prepared for initial site development activity in
accordance with the 2009 KCSWDM. CSWPPPs will also be part of the building permits
for each lot.
5. Oil Control
This project is not a high use site; therefore, this requirement does not apply.
6. Aquifer Protection Area
Per Reference 11-B of the City of Renton Amendment, this project site is not within and
Aquifer Protection Area.
Renton 701 Townhomes DCI 15375
3. Offsite Analysis
Renton 701 Townhomes DCI 15375
3. Offsite Analysis
Task 1 - Study Area Definition & Maps
The study area is defined as the upstream contributing area located west of the Site and the
downstream area extending 1 mile from the Project Site.
Task 2 - Resource Review
1. Adopted Basin Plan, Basin Reconnaissance Summary Reports
No special basin plan requirements were identified through the pre-application process.
2. FEMA Maps
The Site is entirely within Zone X. The FEMA map did not reveal any problems.
3. Offsite Analysis Reports Finalized Drainage Studies
No other offsite analyses were reviewed.
4. Sensitive Area Folio
The Site has been identified as an Erosion Hazard and Landslide Area by City of Renton
GIS, based on the much of the site slopes exceeding 15%. A steep slope exists along the
western margin of the site; however, this was created by past filling activity. This slope is
proposed to be reduced to 15 feet or less in height so as to not be a regulated slope. Project
runoff will be discharged at a location where downstream slopes are less than 15% for a
distance of at least 50 feet.
5. Drainage Complaints and Studies
No downstream complaints have been identified for this Site.
6. Road Drainage Problems
None noted.
7. King County Soils Survey
The USGS Soil Map identifies site soils to be Alderwood gravelly sandy loam and Ragnar-
Indianola soils (Figure 1.4). The soil map did not identify any drainage related problems.
8. Wetlands Inventory
N/A
9. Migrating River Studies
No channel migration hazard areas are within the study area.
10. WSDOE Clean Water Act Section 303d
WSDOE Water Quality Assessment for Washington map was accessed on 10/25/16. The
map indicate that John’s Creek, approximately ¼ mile downstream from the Site, is
impaired for temperature, bacteria and dissolved oxygen. No mitigation is required at this
time.
Renton 701 Townhomes DCI 15375
11. King County Designated Water Quality Problems
There are no King County identified water quality problems listed in the 2009 KCSWDM
Reference Section 10 posted on King County's Surface Water Design Manual website.
12. Stormwater Compliance Plans
N/A
Task 3 - Field Reconnaissance
A field reconnaissance was conducted on November 19, 2015, (weather conditions were partly
cloudy and dry). No evidence of flooding or erosion problems were observed. The upstream
runoff is intercepted by a private drainage system to the north and Sunset Boulevard to the east.
The resource review did not identify any conditions that warranted extended field review
beyond a ¼ mile downstream.
Task 4 - Drainage System Description And Problem Screening
See Figure 3.1 – Offsite Analysis Map
Runoff exists the property and flows northwest through PSE right-of-way down a well
vegetated slope of less than 15% for at least 50 feet. Runoff continues west for another 200 feet
through the PSE and I-405 rights-a-way consisting of well vegetated natural and constructed
slopes. At the toe of the I-405 right-of-way cut embankment, runoff enters the stormwater
conveyance system in Interstate 405. Safety concerns precluded direct inspection of the I405
conveyance system; however Renton GIS runoff is conveyed north in a pipe system for
approximately 950 feet, near the vicinity of where John’s Creek is conveyed under I-405. The
I-405 piped conveyance system appears to turn west at this location and convey runoff down
the west slope of the right-of-way and combine with the piped flow of John’s Creek. This point
of combination is at or beyond the ¼ mile downstream point from the Site.
Task 5 – Mitigation of Existing or Potential Problems
The project will provide Peak Rate Flow Control. No problems were identified that would
warrant a higher level of flow control or additional mitigation.
It is Duncanson Company’s opinion from the available information that the developed Site will
not create or aggravate any downstream problems.
Job No. 15375Drawn: HMDScale: NTS
FIGURE 3.1 - Offsite Analysis Map
&LYLO(QJLQHHULQJā6XUYH\LQJā/DQG3ODQQLQJ
145 SW 155th Street, Suite 102
Seattle, Washington 98166
Phone 206.244.4141
Fax 206.244.4455
Renton 701 Townhomes DCI 15375
4. Flow Control Analysis and Design
Renton 701 Townhomes DCI 15375
4. Flow Control and Water Quality Facility Analysis and Design
Part A – Existing Site Hydrology
The Site has been previously graded and filled, and was historically developed with a small
building. Asphalt and crushed rock surfacing remain in the central, eastern portion of the site.
These surfaces were modeled in their existing condition as impervious. A large portion of the
Site is covered with brush, blackberries and only a few trees. These areas were modeled as
50% pasture and 50% forested. The slope in the south and western margin of the site is covered
with small to medium size deciduous alder and maple trees. This portion of the Site was
modeled as forested. Site soils consist of fill underlain by till; therefore, till soil conditions
were assumed for stormwater modeling.
See Figure 4.1—Predeveloped Conditions for delineation of these areas. KCRTS input
parameters are tabulated below.
Results
A time series file was generated for the predeveloped conditions stated above, using SeaTac
Region, scale factor 1.00, reduced record and hourly time steps. The time series files for the
predeveloped basin has the following peaks:
Site Basin Flow Frequency Analysis
Time Series File:predev site basin hourly.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) Period
0.079 5 2/09/01 15:00 0.155 1 100.00 0.990
0.056 7 1/05/02 16:00 0.090 2 25.00 0.960
0.090 2 2/27/03 7:00 0.085 3 10.00 0.900
0.051 8 8/26/04 2:00 0.079 4 5.00 0.800
0.061 6 10/28/04 16:00 0.079 5 3.00 0.667
0.085 3 1/18/06 16:00 0.061 6 2.00 0.500
0.079 4 11/24/06 3:00 0.056 7 1.30 0.231
0.155 1 1/09/08 6:00 0.051 8 1.10 0.091
Computed Peaks 0.133 50.00 0.980
Site Basin
Land Type Acres
Impervious 0.20
Till Forest 0.395
Till Pasture 0.265
Total 0.86
Sunset Blvd
Land Type Acres
Impervious 0.05
Till Pasture 0.06
Total 0.11
Renton 701 Townhomes DCI 15375
Sunset Blvd
Flow Frequency Analysis
Time Series File:predev sunset blvd hourly.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) Period
0.015 5 2/09/01 2:00 0.031 1 100.00 0.990
0.012 7 1/05/02 16:00 0.018 2 25.00 0.960
0.018 2 2/27/03 7:00 0.018 3 10.00 0.900
0.012 8 8/26/04 2:00 0.016 4 5.00 0.800
0.015 6 10/28/04 16:00 0.015 5 3.00 0.667
0.016 4 1/18/06 16:00 0.015 6 2.00 0.500
0.018 3 10/26/06 0:00 0.012 7 1.30 0.231
0.031 1 1/09/08 6:00 0.012 8 1.10 0.091
Computed Peaks 0.027 50.00 0.980
Job No. 15375Drawn: HMDScale: 1"=40'
Fig 4.1 Pre-Developed Basin Map
&LYLO(QJLQHHULQJā6XUYH\LQJā/DQG3ODQQLQJ
145 SW 155th Street, Suite 102
Seattle, Washington 98166
Phone 206.244.4141
Fax 206.244.4455
1 inch = ft.
(IN FEET)
GRAPHIC SCALE
40
Renton 701 Townhomes DCI 15375
Part B – Developed Site Hydrology
Project development will result in the addition of 23,280 SF of new and/or replaced impervious
surface in the form of roof, patio, road and driveway. The remainder of the site was modeled as
landscaping (till grass). The western edge of the property will continue to sheet flow to the
west and not be collected. This area was modeled as a bypass basin. There is 0.06 acres of
pervious pavers on the site, which were modeled as 50% till grass and 50% impervious.
See Figure 4.2—Postdeveloped Conditions for delineation of these areas. KCRTS input
parameters are tabulated below.
Site Basin
Land Type Acres
Impervious 0.49
Till Grass 0.12
Bypass Till Grass 0.25
Total 0.86
Sunset Blvd
Land Type Acres
Impervious 0.08
Till Grass 0.03
Total 0.11
Results
The postdeveloped, BMP-credited time series files was generated using Seatac Region, scale
factor 1.00, reduced record, hourly and 15-minute time steps. The time series files for the two
postdeveloped basins computed the following peaks:
HOURLY TIME STEP RESULTS
Site (undetained)
Flow Frequency Analysis
Time Series File:postdev site basin hourly.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) Period
0.129 6 2/09/01 2:00 0.257 1 100.00 0.990
0.110 8 1/05/02 16:00 0.181 2 25.00 0.960
0.155 3 12/08/02 18:00 0.155 3 10.00 0.900
0.124 7 8/26/04 2:00 0.148 4 5.00 0.800
0.148 4 10/28/04 16:00 0.138 5 3.00 0.667
0.138 5 1/18/06 16:00 0.129 6 2.00 0.500
0.181 2 10/26/06 0:00 0.124 7 1.30 0.231
0.257 1 1/09/08 6:00 0.110 8 1.10 0.091
Computed Peaks 0.232 50.00 0.980
&LYLO(QJLQHHULQJā6XUYH\LQJā/DQG3ODQQLQJ
145 SW 155th Street, Suite 102
Seattle, Washington 98166
Phone 206.244.4141
Fax 206.244.4455
1 inch = ft.
(IN FEET)
GRAPHIC SCALE
40
Job No. 15375Drawn: HMDScale: 1"=40'
Fig 4.2 Post-Developed Basin Map
Renton 701 Townhomes DCI 15375
Bypass Basin
Flow Frequency Analysis
Time Series File:postdev bypass hourly.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) Period
0.022 4 2/09/01 2:00 0.053 1 100.00 0.990
0.011 7 1/05/02 16:00 0.028 2 25.00 0.960
0.028 2 2/27/03 7:00 0.023 3 10.00 0.900
0.005 8 3/24/04 19:00 0.022 4 5.00 0.800
0.012 6 1/05/05 8:00 0.020 5 3.00 0.667
0.023 3 1/18/06 16:00 0.012 6 2.00 0.500
0.020 5 11/24/06 3:00 0.011 7 1.30 0.231
0.053 1 1/09/08 6:00 0.005 8 1.10 0.091
Computed Peaks 0.045 50.00 0.980
Combined undetained Site and Bypass
Flow Frequency Analysis
Time Series File:postdev combo hourly.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) Period
0.147 6 2/09/01 2:00 0.302 1 100.00 0.990
0.116 8 1/05/02 16:00 0.178 2 25.00 0.960
0.178 2 2/27/03 7:00 0.177 3 10.00 0.900
0.122 7 8/26/04 2:00 0.156 4 5.00 0.800
0.148 5 10/28/04 16:00 0.148 5 3.00 0.667
0.156 4 1/18/06 16:00 0.147 6 2.00 0.500
0.177 3 10/26/06 0:00 0.122 7 1.30 0.231
0.302 1 1/09/08 6:00 0.116 8 1.10 0.091
Computed Peaks 0.261 50.00 0.980
Note the combined 100-year peak flow increase is > 0.1 CFS confirming that a flow control
facility is required.
Renton 701 Townhomes DCI 15375
Sunset Blvd
Flow Frequency Analysis
Time Series File:postdev sunset blvd hourly.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) Period
0.022 6 2/09/01 2:00 0.044 1 100.00 0.990
0.018 8 1/05/02 16:00 0.030 2 25.00 0.960
0.027 3 2/27/03 7:00 0.027 3 10.00 0.900
0.021 7 8/26/04 2:00 0.024 4 5.00 0.800
0.024 4 10/28/04 16:00 0.024 5 3.00 0.667
0.024 5 1/18/06 16:00 0.022 6 2.00 0.500
0.030 2 10/26/06 0:00 0.021 7 1.30 0.231
0.044 1 1/09/08 6:00 0.018 8 1.10 0.091
Computed Peaks 0.039 50.00 0.980
Note the developed Sunset Blvd 100-year peak flow is 0.04 CFS and will cause negligible flow
to the existing Sunset Blvd storm drain.
Part C – Performance Standards
The City of Renton specifies Peak Rate Flow Control and Basic Water Quality treatment as the
required performance standards for this Site.
Part D – Flow Control Systems
BMPs
Per the KCSWDM, the individual Site or Lots are required to have Flow Control BMPs. Full
Dispersal is not considered feasible due to lack of available flow paths. Due to fill and till soils
and slope considerations, infiltration was also deemed infeasible. Flow control BMPs are
proposed to take the form permeable pavers for the internal site walkways.
The individual lots sizes vary from 740 SF to 910 SF, which fall in the small lot category,
requiring mitigation of at least 10% of the Site/Lot areas. There are permeable pavers adjacent
to each lot. The sum of all the lot areas is 12,236 SF. There is approximately 2,805 SF of
permeable pavers proposed. This averages out to 23% of the Site/Lot areas, thereby satisfying
the BMP requirement. While the BMP requirement is satisfied, as a conservative measure, no
credit was taken for less impervious area in computing post developed runoff.
Flow Control Facility
A detention tank was selected to provide flow control. Multiple iterations of level pool routing
were run using KCRTS to find an acceptable configuration. An 80-foot long by 10-foot
diameter detention tank was found to achieve the required performance including combination
of the bypass runoff for downstream point of compliance. Additional iterations at the final
design stage will likely result in a smaller storage facility. KCRTS detention sizing results are
provided below.
Renton 701 Townhomes DCI 15375
Retention/Detention Facility
Type of Facility: Detention Tank
Tank Diameter: 10.00 ft
Tank Length: 80.00 ft
Effective Storage Depth: 9.50 ft
Stage 0 Elevation: 154.00 ft
Storage Volume: 6166. cu. ft
Riser Head: 9.50 ft
Riser Diameter: 12.00 inches
Number of orifices: 2
Full Head Pipe
Orifice # Height Diameter Discharge Diameter
(ft) (in) (CFS) (in)
1 0.00 0.88 0.065
2 4.50 0.63 0.024 4.0
Top Notch Weir: None
Outflow Rating Curve: None
Stage Elevation Storage Discharge Percolation
(ft) (ft) (cu. ft) (ac-ft) (cfs) (cfs)
0.00 154.00 0. 0.000 0.000 0.00
0.01 154.01 4. 0.000 0.002 0.00
0.02 154.02 7. 0.000 0.003 0.00
0.03 154.03 11. 0.000 0.003 0.00
0.04 154.04 14. 0.000 0.004 0.00
0.05 154.05 18. 0.000 0.005 0.00
0.06 154.06 22. 0.000 0.005 0.00
0.07 154.07 25. 0.001 0.006 0.00
0.23 154.23 88. 0.002 0.010 0.00
0.40 154.40 163. 0.004 0.013 0.00
0.56 154.56 239. 0.005 0.016 0.00
0.72 154.72 320. 0.007 0.018 0.00
0.88 154.88 406. 0.009 0.020 0.00
1.04 155.04 497. 0.011 0.021 0.00
1.20 155.20 591. 0.014 0.023 0.00
1.36 155.36 689. 0.016 0.025 0.00
1.52 155.52 790. 0.018 0.026 0.00
1.68 155.68 894. 0.021 0.027 0.00
1.84 155.84 1001. 0.023 0.029 0.00
2.01 156.01 1118. 0.026 0.030 0.00
2.17 156.17 1230. 0.028 0.031 0.00
2.33 156.33 1344. 0.031 0.032 0.00
2.49 156.49 1461. 0.034 0.033 0.00
2.65 156.65 1579. 0.036 0.034 0.00
2.81 156.81 1698. 0.039 0.035 0.00
2.97 156.97 1820. 0.042 0.036 0.00
3.13 157.13 1942. 0.045 0.037 0.00
3.29 157.29 2066. 0.047 0.038 0.00
3.45 157.45 2190. 0.050 0.039 0.00
3.62 157.62 2324. 0.053 0.040 0.00
Renton 701 Townhomes DCI 15375
3.78 157.78 2450. 0.056 0.041 0.00
3.94 157.94 2577. 0.059 0.042 0.00
4.10 158.10 2705. 0.062 0.043 0.00
4.26 158.26 2832. 0.065 0.043 0.00
4.42 158.42 2960. 0.068 0.044 0.00
4.50 158.50 3024. 0.069 0.045 0.00
4.51 158.51 3032. 0.070 0.045 0.00
4.52 158.52 3040. 0.070 0.045 0.00
4.53 158.53 3048. 0.070 0.047 0.00
4.54 158.54 3056. 0.070 0.047 0.00
4.55 158.55 3064. 0.070 0.047 0.00
4.71 158.71 3192. 0.073 0.051 0.00
4.87 158.87 3320. 0.076 0.053 0.00
5.04 159.04 3455. 0.079 0.055 0.00
5.20 159.20 3582. 0.082 0.057 0.00
5.36 159.36 3709. 0.085 0.059 0.00
5.52 159.52 3834. 0.088 0.060 0.00
5.68 159.68 3959. 0.091 0.062 0.00
5.84 159.84 4083. 0.094 0.063 0.00
6.00 160.00 4206. 0.097 0.065 0.00
6.16 160.16 4327. 0.099 0.066 0.00
6.32 160.32 4447. 0.102 0.067 0.00
6.48 160.48 4566. 0.105 0.069 0.00
6.65 160.65 4690. 0.108 0.070 0.00
6.81 160.81 4804. 0.110 0.071 0.00
6.97 160.97 4917. 0.113 0.072 0.00
7.13 161.13 5027. 0.115 0.074 0.00
7.29 161.29 5134. 0.118 0.075 0.00
7.45 161.45 5239. 0.120 0.076 0.00
7.61 161.61 5341. 0.123 0.077 0.00
7.77 161.77 5439. 0.125 0.078 0.00
7.93 161.93 5534. 0.127 0.079 0.00
8.09 162.09 5626. 0.129 0.080 0.00
8.26 162.26 5718. 0.131 0.081 0.00
8.42 162.42 5800. 0.133 0.082 0.00
8.58 162.58 5876. 0.135 0.083 0.00
8.74 162.74 5947. 0.137 0.084 0.00
8.90 162.90 6012. 0.138 0.085 0.00
9.06 163.06 6069. 0.139 0.086 0.00
9.22 163.22 6116. 0.140 0.087 0.00
9.38 163.38 6152. 0.141 0.088 0.00
9.50 163.50 6166. 0.142 0.089 0.00
9.60 163.60 6166. 0.142 0.397 0.00
9.70 163.70 6166. 0.142 0.961 0.00
9.80 163.80 6166. 0.142 1.690 0.00
9.90 163.90 6166. 0.142 2.480 0.00
10.00 164.00 6166. 0.142 2.770 0.00
10.10 164.10 6166. 0.142 3.020 0.00
10.20 164.20 6166. 0.142 3.260 0.00
10.30 164.30 6166. 0.142 3.480 0.00
10.40 164.40 6166. 0.142 3.680 0.00
10.50 164.50 6166. 0.142 3.880 0.00
Renton 701 Townhomes DCI 15375
Hyd Inflow Outflow Peak Storage
Stage Elev (Cu-Ft) (Ac-Ft)
1 0.26 0.07 6.22 160.22 4371. 0.100
2 0.18 0.04 3.04 157.04 1875. 0.043
3 0.15 0.04 4.06 158.06 2669. 0.061
4 0.15 0.03 2.78 156.78 1674. 0.038
5 0.14 0.05 5.00 159.00 3425. 0.079
6 0.13 0.06 5.28 159.28 3644. 0.084
7 0.12 0.03 2.10 156.10 1179. 0.027
8 0.11 0.03 2.03 156.03 1131. 0.026
Hyd R/D Facility Tributary Reservoir POC Outflow
Outflow Inflow Inflow Target Calc
1 0.07 0.05 ******** ******* 0.10
2 0.04 0.01 ******** ******* 0.04
3 0.04 0.03 ******** ******* 0.06
4 0.03 0.01 ******** ******* 0.04
5 0.05 0.02 ******** ******* 0.07
6 0.06 0.02 ******** ******* 0.08
7 0.03 0.00 ******** ******* 0.03
8 0.03 0.01 ******** ******* 0.04
----------------------------------
Route Time Series through Facility
Inflow Time Series File:postdev site basin hourly.tsf
Outflow Time Series File:TankoutHourly
POC Time Series File:Downstreamout Hourly
Inflow/Outflow Analysis
Peak Inflow Discharge: 0.257 CFS at 6:00 on Jan 9 in Year 8
Peak Outflow Discharge: 0.066 CFS at 11:00 on Jan 9 in Year 8
Peak Reservoir Stage: 6.22 Ft
Peak Reservoir Elev: 160.22 Ft
Peak Reservoir Storage: 4371. Cu-Ft
: 0.100 Ac-Ft
Add Time Series:postdev bypass hourly.tsf
Peak Summed Discharge: 0.100 CFS at 9:00 on Jan 9 in Year 8
Point of Compliance File:Downstreamout Hourly.tsf
Flow Frequency Analysis
Time Series File:tankouthourly.tsf
Project Location:Sea-Tac
Renton 701 Townhomes DCI 15375
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) (ft) Period
0.058 2 2/09/01 19:00 0.066 6.22 1 100.00 0.990
0.030 8 1/05/02 18:00 0.058 5.28 2 25.00 0.960
0.043 5 3/06/03 21:00 0.057 5.18 3 10.00 0.900
0.031 7 8/24/04 0:00 0.055 5.00 4 5.00 0.800
0.037 6 1/05/05 10:00 0.043 4.06 5 3.00 0.667
0.055 4 1/18/06 22:00 0.037 3.06 6 2.00 0.500
0.057 3 11/24/06 7:00 0.031 2.10 7 1.30 0.231
0.066 1 1/09/08 11:00 0.030 2.03 8 1.10 0.091
Computed Peaks 0.064 5.89 50.00 0.980
Flow Frequency Analysis
Time Series File:downstreamout hourly.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) Period
0.077 2 2/09/01 18:00 0.100 1 100.00 0.990
0.037 7 1/05/02 16:00 0.077 2 25.00 0.960
0.062 5 2/28/03 3:00 0.072 3 10.00 0.900
0.031 8 8/24/04 0:00 0.070 4 5.00 0.800
0.047 6 1/05/05 8:00 0.062 5 3.00 0.667
0.070 4 1/18/06 21:00 0.047 6 2.00 0.500
0.072 3 11/24/06 6:00 0.037 7 1.30 0.231
0.100 1 1/09/08 9:00 0.031 8 1.10 0.091
Computed Peaks 0.092 50.00 0.980
Peak Flow Control Performance Check
Storm Event Predeveloped Peak Postdeveloped Peak
Downstream POC
2-yr 0.061 0.047
10-yr 0.085 0.072
100-yr 0.155 0.100
Renton 701 Townhomes DCI 15375
Next, 15-minute time step runoff files were generated for the Site and Bypass Basin for the
purposes of determining the peak release rate from the site for allowance of discharge onto a
rock pad. The 15-minute Site runoff file was routed through the above designed detention
system and the discharged was combined with the 15-minute Bypass basin. The result was a
100-year, 15-minute peak discharge rate of 0.164 CFS, which is within the allowance for
discharge onto a rock pad per Core Requirement #1. Detailed results are presented below:
15-MINUTE TIME STEP RESULTS
Site (undetained)
Flow Frequency Analysis
Time Series File:postdev site basin 15min.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) Period
0.234 6 8/27/01 18:00 0.639 1 100.00 0.990
0.163 8 9/17/02 17:45 0.468 2 25.00 0.960
0.468 2 12/08/02 17:15 0.321 3 10.00 0.900
0.188 7 8/23/04 14:30 0.269 4 5.00 0.800
0.254 5 10/28/04 16:00 0.254 5 3.00 0.667
0.269 4 10/27/05 10:45 0.234 6 2.00 0.500
0.321 3 10/25/06 22:45 0.188 7 1.30 0.231
0.639 1 1/09/08 6:30 0.163 8 1.10 0.091
Computed Peaks 0.582 50.00 0.980
Bypass Basin
Flow Frequency Analysis
Time Series File:postdev bypass 15min.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) Period
0.030 4 2/09/01 12:45 0.126 1 100.00 0.990
0.014 7 1/06/02 1:00 0.078 2 25.00 0.960
0.055 3 12/08/02 17:15 0.055 3 10.00 0.900
0.005 8 8/26/04 1:00 0.030 4 5.00 0.800
0.078 2 11/17/04 5:00 0.023 5 3.00 0.667
0.022 6 1/18/06 15:00 0.022 6 2.00 0.500
0.023 5 11/24/06 1:00 0.014 7 1.30 0.231
0.126 1 1/09/08 6:30 0.005 8 1.10 0.091
Computed Peaks 0.110 50.00 0.980
Renton 701 Townhomes DCI 15375
Detention Performance 15-minute
Type of Facility: Detention Tank
Tank Diameter: 10.00 ft
Tank Length: 80.00 ft
Effective Storage Depth: 9.50 ft
Stage 0 Elevation: 154.00 ft
Storage Volume: 6166. cu. ft
Riser Head: 9.50 ft
Riser Diameter: 12.00 inches
Number of orifices: 2
Full Head Pipe
Orifice # Height Diameter Discharge Diameter
(ft) (in) (CFS) (in)
1 0.00 0.88 0.065
2 4.50 0.63 0.024 4.0
Top Notch Weir: None
Outflow Rating Curve: None
Hyd Inflow Outflow Peak Storage
Target Calc Stage Elev (Cu-Ft) (Ac-Ft)
1 0.64 ******* 0.07 6.16 160.16 4330. 0.099
2 0.47 ******* 0.04 3.07 157.07 1895. 0.043
3 0.32 ******* 0.04 3.12 157.12 1932. 0.044
4 0.27 ******* 0.03 1.75 155.75 942. 0.022
5 0.25 ******* 0.04 2.89 156.89 1756. 0.040
6 0.23 ******* 0.03 1.55 155.55 810. 0.019
7 0.19 ******* 0.03 2.18 156.18 1239. 0.028
8 0.16 ******* 0.03 1.63 155.63 864. 0.020
----------------------------------
Route Time Series through Facility
Inflow Time Series File:postdev site basin 15min.tsf
Outflow Time Series File:Tankout15min.tsf
Inflow/Outflow Analysis
Peak Inflow Discharge: 0.639 CFS at 6:30 on Jan 9 in Year 8
Peak Outflow Discharge: 0.066 CFS at 11:00 on Jan 9 in Year 8
Peak Reservoir Stage: 6.16 Ft
Peak Reservoir Elev: 160.16 Ft
Peak Reservoir Storage: 4330. Cu-Ft
: 0.099 Ac-Ft
Renton 701 Townhomes DCI 15375
Downstream Discharge Rate without Bypass
Flow Frequency Analysis
Time Series File:tankout15min.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) (ft) Period
0.059 2 2/09/01 17:30 0.066 6.16 1 100.00 0.990
0.031 8 1/05/02 16:00 0.059 5.32 2 25.00 0.960
0.043 5 3/06/03 18:45 0.057 5.20 3 10.00 0.900
0.031 7 8/23/04 22:00 0.055 5.03 4 5.00 0.800
0.037 6 1/05/05 7:45 0.043 4.11 5 3.00 0.667
0.055 4 1/18/06 20:15 0.037 3.18 6 2.00 0.500
0.057 3 11/24/06 5:15 0.031 2.18 7 1.30 0.231
0.066 1 1/09/08 11:00 0.031 2.17 8 1.10 0.091
Computed Peaks 0.064 5.88 50.00 0.980
Downstream Discharge Rate with Bypass
Flow Frequency Analysis
Time Series File:downstreamout 15min.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) Period
0.079 4 2/09/01 12:45 0.164 1 100.00 0.990
0.042 7 1/05/02 15:15 0.105 2 25.00 0.960
0.087 3 12/08/02 17:15 0.087 3 10.00 0.900
0.031 8 8/23/04 22:00 0.079 4 5.00 0.800
0.105 2 11/17/04 5:00 0.070 5 3.00 0.667
0.068 6 1/18/06 20:15 0.068 6 2.00 0.500
0.070 5 11/24/06 5:15 0.042 7 1.30 0.231
0.164 1 1/09/08 6:30 0.031 8 1.10 0.091
Computed Peaks 0.144 50.00 0.980
Part E – Water Quality System
This site is in a Basic Water Quality area. A stormfilter is proposed to provide water quality
treatment. Detailed sizing and selection of the stormfilter will be prepared at the building
permit stage.
Renton 701 Townhomes DCI 15375
6. Special Reports and Studies
Renton 701 Townhomes DCI 15375
6. Special Reports and Studies
A geotechnical engineering report has been prepared by E3RA. A copy of that report is
included in this Section.
E RA
3
Geotechnical Engineering Report
701 Sunset Blvd NE
Renton, Washington
P/Ns 311990001, 3119900010, 3119900005
Submitted to:
Totenham, LLC
Attn: Joe Notarangelo
50 116th Ave SE, Suite 111
Bellevue, Washington 98004
Submitted by:
E3RA, Inc.
PO Box 44840
Tacoma, Washington 98448
(253) 537-9400
April 16, 2015
Project No. T15034
i
TABLE OF CONTENTS
Page No.
1.0 SITE AND PROJECT DESCRIPTION .................................................................................... 1
2.0 EXPLORATORY METHODS ................................................................................................... 2
2.1 Test Pit Procedures ..................................................................................................... 2
3.0 SITE CONDITIONS ................................................................................................................. 3
3.1 Surface Conditions....................................................................................................... 3
3.2 Soil Conditions ............................................................................................................. 3
3.3 Groundwater Conditions .............................................................................................. 3
3.4 Seismic Conditions ...................................................................................................... 4
3.5 Liquefaction Potential .................................................................................................. 4
4.0 CONCLUSIONS AND RECOMMENDATIONS ....................................................................... 4
4.1 Site Preparation ........................................................................................................... 5
4.2 Spread Footings ........................................................................................................... 7
4.3 Slab-On-Grade Floors.................................................................................................. 8
4.4 Asphalt Pavement ........................................................................................................ 8
4.5 Structural Fill ................................................................................................................ 9
5.0 RECOMMENDED ADDITIONAL SERVICES ........................................................................ 10
6.0 CLOSURE .............................................................................................................................. 11
List of Tables
Table 1. Approximate Locations and Depths of Explorations ...................................................................... 2
List of Figures
Figure 1. Topographic and Location Map
Figure 2. Site and Exploration Plan
APPENDIX A
Soil Classification Chart and Key to Test Data ........................................................................................... A-1
Logs of Test Pits TP-1 through TP-3................................................................................................ A-2…A-4
PO Box 44840
Tacoma, WA 98448
253-537-9400
253-537-9401 Fax
E3RA
April 16, 2015
T15034
Totenham, LLC
50 116th Ave SE, Suite 111
Bellevue, WA 98004
Attention: Joe Notarangelo
Subject: Geotechnical Engineering Report
701 Sunset Blvd NE
P/Ns 3119900011, 3119900010, 3119900005
Renton, Washington
Dear Mr. Notarangelo:
E3RA, Inc. (E3RA) is pleased to submit this revised report describing the results of our geotechnical
engineering evaluation for the improvements planned at 701 Sunset Blvd NE in Renton, Washington.
This report has been prepared for the exclusive use of the Totenham, LLC and their consultants, for specific
application to this project, in accordance with generally accepted geotechnical engineering practice.
1.0 SITE AND PROJECT DESCRIPTION
The project site consists of three separate, but adjacent tax parcels on the west side of Sunset Blvd NE, located
directly northwest of its intersection with NE 7th St in Renton, Washington, as shown on the enclosed
Topographic and Location Map (Figure 1). The subject property contains a frontage on Sunset Blvd NE of
approximately 200 feet, and extends west of the roadway ± 125 to 200 feet; encompassing just under one acre.
Currently, the property is undeveloped, with the only distinguishing site feature being a “U” shaped gravel
driveway which enters/exits Sunset Blvd NE along the east side of the site. Generally, the easternmost
two-thirds of the property is relatively level, containing a slight slope from east to west, no steeper than
15 percent. The western third of the site consists of a moderate to steep slope which descends to the west at
grades of 50 to 60 percent and represents an elevation change of 15 to 20 feet. Directly west of the subject
property is long, thin parcel owned by Puget Sound Energy, which acts as a pathway for transmission towers
which service the area. One such transmission tower is in close proximity to the project area. Areas west of
this parcel are steeply sloped, and descend down to I-405. The western boundary of the site is approximately
200 feet east of I-405.
Improvement plans involve the clearing/stripping of the site and developing 10 to 12 townhouses within its
confines. Preliminary discussions have the townhouses being three-story, wood-framed structures. Garages
will either be attached or detached, with no preliminary layouts available thus far. Paved driving and parking
surfaces will also be incorporated into the proposed development.
April 16, 2015 E3RA, Inc.
T15034 / Totenham, LLC – 701 Sunset Blvd NE, Renton Geotechnical Engineering Report
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2.0 EXPLORATORY METHODS
We previously explored surface and subsurface conditions at the project site on January 21, 2015. Our
exploration and evaluation program comprised the following elements:
• Surface reconnaissance of the site;
• Three test pits (designated TP-1 through TP-3), advanced on January 21, 2015; and
• A review of published geologic and seismologic maps and literature.
Table 1 summarizes the approximate functional locations and termination depths of our subsurface
explorations, and Figure 2 depicts their approximate relative locations. The following sections describe the
procedures used for excavation of test pits.
TABLE 1
APPROXIMATE LOCATIONS AND DEPTHS OF EXPLORATIONS
Exploration Functional Location
Termination
Depth
(feet)
TP-1
TP-2
TP-3
Eastern third of the site, north end of “U” shaped gravel driveway
Eastern third of the site, south end of “U” shaped gravel driveway
Centrally within the site, west of the “U” shaped gravel driveway
7½
7½
7½
The specific number and locations of our explorations were selected in relation to the existing site features,
under the constraints of surface access, underground utility conflicts, and budget considerations.
It should be realized that the explorations performed and utilized for this evaluation reveal subsurface
conditions only at discrete locations across the project site and that actual conditions in other areas could vary.
Furthermore, the nature and extent of any such variations would not become evident until additional
explorations are performed or until construction activities have begun. If significant variations are observed
at that time, we may need to modify our conclusions and recommendations contained in this report to reflect
the actual site conditions.
2.1 Test Pit Procedures
Our exploratory test pits were excavated with a rubber-tracked mini-excavator operated by an excavation
contractor under subcontract to E3RA. A geotechnical engineer from our firm observed the test pit
excavations, collected soil samples, and logged the subsurface conditions.
The enclosed test pit logs indicate the vertical sequence of soils and materials encountered in each test pit,
based on our field classifications. Where a soil contact was observed to be gradational or undulating, our logs
indicate the average contact depth. We estimated the relative density and consistency of the in-situ soils by
means of the excavation characteristics and the stability of the test pit sidewalls. Our logs also indicate the
approximate depths of any sidewall caving or groundwater seepage observed in the test pits. The soils were
classified visually in general accordance with the system described in Figure A-1, which includes a key to the
exploration logs. Summary logs of the explorations are included as Figures A-2 through A-4.
April 16, 2015 E3RA, Inc.
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3.0 SITE CONDITIONS
The following sections present our observations, measurements, findings, and interpretations regarding,
surface, soil, groundwater, and infiltration conditions.
3.1 Surface Conditions
As previously described, the project site consists of three separate but adjacent tax parcels on the west side of
Sunset Blvd NE, located directly northwest of its intersection with NE 7th St, in Renton, Washington. It is
located on the outskirts of a larger residential development further to the east, and is positioned on the top of a
small ridgeline which runs north/south, forming the eastern boundary of I-405. The eastern two-thirds of the
site is relatively level, containing a slight slope (less than 15 percent) from east to west. This portion of the site
has limited vegetation, containing only a sparse grass cover and limited gravel surfacing along the “U” shaped
driveway. The western third of the site consists of a moderate to steep slope which descends to the west at
grades of 50 to 60 percent and represents an elevation change of 15 to 20 feet. The slope face itself is densely
vegetated with thin conifers, blackberry bushes, and other brush, and does not display any irregularities
indicating slope failure, such as ancient or recent landslide scarps, hummocks, slide blocks, or jack-strawed
trees. The adjacent property to the west is owned by Puget Sound Energy, and acts as a pathway for
transmission towers servicing the area. A narrow driveway to this property is located directly south of the
project site. The western boundary of the PSE property is marked by a chainlink fence, with areas west of this
mark being steeply sloped and directly descend down to I-405.
No hydrologic features were observed on site, such as seeps, springs, ponds and streams.
3.2 Soil Conditions
Our subsurface explorations revealed relatively consistent subgrade conditions across the site. The entirety of
the site contains a surface mantle of sod, topsoil, or gravel surfacing, typically no more than 6 inches thick.
Underlying this material, a fill zone spans much of the site, typically extending to 4½ feet below existing grade.
The uppermost 3 feet of the fill material is comprised of silty sand in a medium dense in-situ condition. From
3½ to 4½ feet below existing grade, logs, woody debris and general refuse were incorporated into the fill
material. Native soils on site consist of glacial till deposited during the most recent glaciation of the area; the
Vashon Stade of the Fraser Glaciation. Glacial till deposits observed in our subsurface explorations were all
moderately weathered and comprised of gravelly, silty sand in a medium dense in-situ condition. Unweathered
deposited are likely encountered with depth.
In the Geologic Map of the Renton Quadrangle, King County, Washington, as prepared by the Department of
the Interior United States Geological Survey (USGS) (1965), the project site is mapped as containing Qgt, or
Vashon Glacial Till. These deposits are described as being a generally compact, coherent, unsorted mixture of
sand, silt, clay and gravel. Our subsurface explorations generally correspond with the mapping performed by
the USGS.
The enclosed exploration logs (Appendix A) provide a detailed description of the soil strata encountered in
our subsurface explorations.
3.3 Groundwater Conditions
At the time of our reconnaissance and subsurface explorations (January 21, 2015), we did not encounter
groundwater seepage in any of our subsurface explorations which extended to a maximum depth of 7½ feet
below existing grade. Given the fact that our subsurface explorations were performed in what is generally
April 16, 2015 E3RA, Inc.
T15034 / Totenham, LLC – 701 Sunset Blvd NE, Renton Geotechnical Engineering Report
4
considered the wet season (December through April), we do not anticipate that groundwater levels will rise
higher than that which we observed, and we do not anticipate that groundwater will adversely impact the
proposed improvements.
3.4 Seismic Conditions
Based on our analysis of subsurface exploration logs and our review of published geologic maps, we interpret
the onsite soil conditions to generally correspond with site class D, as defined by Table 20.3-1 in ASCE 7, per
the 2012 International Building Code (IBC).
Using 2012 IBC information on the USGS Design Summary Report website, Risk Category I/II/III seismic
parameters for the site are as follows:
Ss = 1.436 g SMS = 1.436 g SDS = 0.957 g
S1 = 0.539 g SM1 = 0.809 g SD1 = 0.539 g
Using the 2012 IBC information, MCER Response Spectrum Graph on the USGS Design Summary Report
website, Risk Category I/II/III, Sa at a period of 0.2 seconds is 1.44 g and Sa at a period of 1.0 seconds is 0.54g.
The Design Response Spectrum Graph from the same website, using the same IBC information and Risk
Category, Sa at a period of 0.2 seconds is 0.96 g and Sa at a period of 1.0 seconds is 0.54g.
3.5 Liquefaction Potential
Liquefaction is a sudden increase in pore water pressure and a sudden loss of soil shear strength caused by
shear strains, as could result from an earthquake. Research has shown that saturated, loose, fine to medium
sands with a fines (silt and clay) content less than about 20 percent are most susceptible to liquefaction. Our
subsurface explorations did not encounter any loose sand layers or lenses.
4.0 CONCLUSIONS AND RECOMMENDATIONS
Improvement plans involve the clearing/stripping of the site and developing 10 to 12 townhouses within its
confines. Preliminary discussions have the townhouses being three-story, wood-framed structures. Garages
will either be attached or detached, with no preliminary layouts yet available. Paved driving and parking
surfaces will also be incorporated into the proposed development. We offer these recommendations:
• Feasibility: Based on our field explorations, research, and evaluations, the proposed structure
and pavements appear feasible from a geotechnical standpoint.
• Foundation Options: Given the fact that a zone of organic-laden fill material underlies the
site and could result in post-construction settlement if not removed, we recommend the over-
excavation of the building footprint down to native soils; a depth of approximately 4½ feet.
Foundation elements should be constructed on undisturbed native soils, or on structural fill
bearing pads that extend down to native soils. The thickness of structural fill bearing pads, if
used, is at the discretion of the developer. Recommendations for Spread Footings are
provided in Section 4.2.
• Floor Options: Floor sections should bear on medium dense or denser native soils or on
properly compacted structural fill that extends down to medium dense or denser native soil.
We recommend over-excavation of slab-on-grade floor subgrades to a minimum depth of
April 16, 2015 E3RA, Inc.
T15034 / Totenham, LLC – 701 Sunset Blvd NE, Renton Geotechnical Engineering Report
5
4½ feet. Slab-on-grade floors should either be constructed on undisturbed native soils or on
properly compacted structural fill as a floor subbase. If floor construction occurs during wet
conditions, it is likely that a geotextile fabric, placed between the structural fill floor subbase
and native soils, will be necessary. Recommendations for slab-on-grade floors are included in
Section 4.3. Fill underlying floor slabs should be compacted to 95 percent (ASTM:D-1557).
• Pavement Sections: After removal of any organics underlying pavements, we recommend a
conventional pavement section comprised of an asphalt concrete pavement over a crushed
rock base course over a properly prepared (compacted) subgrade or a granular subbase.
All soil subgrades should be thoroughly compacted, then proof-rolled with a loaded dump
truck or heavy compactor. Any localized zones of yielding subgrade disclosed during this
proof-rolling operation should be overexcavated to a depth of 12 inches and replaced with a
suitable structural fill material.
The following sections of this report present our specific geotechnical conclusions and recommendations
concerning site preparation, spread footings, slab-on-grade floors, asphalt pavement, and structural fill. The
Washington State Department of Transportation (WSDOT) Standard Specifications and Standard Plans cited
herein refer to WSDOT publications M41-10, Standard Specifications for Road, Bridge, and Municipal
Construction, and M21-01, Standard Plans for Road, Bridge, and Municipal Construction, respectively.
4.1 Site Preparation
Preparation of the project site should involve erosion control, temporary drainage, clearing, stripping,
excavations, cutting, subgrade compaction, and filling.
Erosion Control: Before new construction begins, an appropriate erosion control system should be installed.
This system should collect and filter all surface water runoff through silt fencing. We anticipate a system of
berms and drainage ditches around construction areas will provide an adequate collection system. Silt
fencing fabric should meet the requirements of WSDOT Standard Specification 9-33.2 Table 3. In addition,
silt fencing should embed a minimum of 6 inches below existing grade. An erosion control system requires
occasional observation and maintenance. Specifically, holes in the filter and areas where the filter has shifted
above ground surface should be replaced or repaired as soon as they are identified.
Temporary Drainage: We recommend intercepting and diverting any potential sources of surface or
near-surface water within the construction zones before stripping begins. Because the selection of an
appropriate drainage system will depend on the water quantity, season, weather conditions, construction
sequence, and contractor's methods, final decisions regarding drainage systems are best made in the field at the
time of construction. Based on our current understanding of the construction plans, surface and subsurface
conditions, we anticipate that curbs, berms, or ditches placed around the work areas will adequately intercept
surface water runoff.
Clearing and Stripping: After surface and near-surface water sources have been controlled, sod, topsoil, and
root-rich soil should be stripped from the site. Our explorations and field observations indicate that the topsoil
horizon is typically 6 inches or less in overall thickness. An organic ridden fill zone was encountered from 3½
to 4½ feet below existing grade, which will also need to be over-excavated within the proposed building
footprint. Stripping is best performed during a period of dry weather.
April 16, 2015 E3RA, Inc.
T15034 / Totenham, LLC – 701 Sunset Blvd NE, Renton Geotechnical Engineering Report
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Site Excavations: Based on our explorations, we expect that excavations will encounter loose to medium dense
silty fill soils and weathered glacial till which can be easily excavated using standard excavation equipment.
Dewatering: Groundwater was not observed in any of our test pit explorations which extended to a maximum
depth of 7½ below existing grade. Given the fact that our test pit explorations were performed in what is
generally considered the rainy season, we do not anticipate that groundwater levels will rise higher than that
which we observed, nor do we anticipate that groundwater will adversely affect the proposed development. If
groundwater is encountered, we anticipate that an internal system of ditches, sumpholes, and pumps will be
adequate to temporarily dewater excavations.
Temporary Cut Slopes: All temporary soil slopes associated with site cutting or excavations should be
adequately inclined to prevent sloughing and collapse. Temporary cut slopes in site soils should be no steeper
than 1½H:1V, and should conform to Washington Industrial Safety and Health Act (WISHA) regulations.
Subgrade Compaction: Exposed subgrades for the foundations of the planned additions should be compacted
to a firm, unyielding state before new concrete or fill soils are placed. Any localized zones of looser granular
soils observed within a subgrade should be compacted to a density commensurate with the surrounding soils.
In contrast, any organic, soft, or pumping soils observed within a subgrade should be overexcavated and
replaced with a suitable structural fill material.
Site Filling: Our conclusions regarding the reuse of onsite soils and our comments regarding wet-weather
filling are presented subsequently. Regardless of soil type, all fill should be placed and compacted according
to our recommendations presented in the Structural Fill section of this report. Specifically, building pad fill
soil should be compacted to a uniform density of at least 95 percent (based on ASTM:D-1557).
Onsite Soils: We offer the following evaluation of these onsite soils in relation to potential use as structural
fill:
• Surficial Organic Soil and Organic-Rich Fill Soils: Where encountered, surficial organic
soils, like duff, topsoil, root-rich soil, and organic-rich fill soils are not suitable for use as
structural fill under any circumstances, due to high organic content. Consequently, this
material can be used only for non-structural purposes, such as in landscaping areas.
• Silty Sand Fill Soils: Much of the site is overlain by 4 feet of fill material. This material
contains a high relative fines (percent silt/clay) content and should be considered extremely
moisture sensitive. Reuse of this soil type should be limited to summer months and moisture
conditioning should be anticipated.
• Glacial Till: This material type underlies much of the project site and is encountered with
depth. These soils are moisture sensitive and will be difficult to reuse during wet weather
conditions.
Permanent Slopes: All permanent cut slopes and fill slopes should be adequately inclined to reduce long-term
raveling, sloughing, and erosion. We generally recommend that no permanent slopes be steeper than 2H:1V.
For all soil types, the use of flatter slopes (such as 2½H:1V) would further reduce long-term erosion and
facilitate revegetation.
April 16, 2015 E3RA, Inc.
T15034 / Totenham, LLC – 701 Sunset Blvd NE, Renton Geotechnical Engineering Report
7
Slope Protection: We recommend that a permanent berm, swale, or curb be constructed along the top edge of
all permanent slopes to intercept surface flow. Also, a hardy vegetative groundcover should be established as
soon as feasible, to further protect the slopes from runoff water erosion. Alternatively, permanent slopes could
be armored with quarry spalls or a geosynthetic erosion mat.
4.2 Spread Footings
In our opinion, conventional spread footings will provide adequate support for the new additions if the
subgrades are properly prepared.
Footing Depths and Widths: For frost and erosion protection, the bases of all exterior footings should bear at
least 18 inches below adjacent outside grades, whereas the bases of interior footings need bear only 12 inches
below the surrounding slab surface level. To reduce post-construction settlements, continuous (wall) and
isolated (column) footings should be at least 18 and 24 inches wide, respectively.
Bearing Subgrades: Given the fact that a zone of organic-laden fill material underlies the site and could result
in post-construction settlement if not removed, we recommend the over-excavation of the building footprint
down to native soils; a depth of approximately 4½ feet. Foundation elements should be constructed on
undisturbed native soils, or on structural fill bearing pads that extend down native soils and compacted to a
density of at least 95 percent (based on ASTM:D-1557). The thickness of structural fill bearing pads, if used,
is at the discretion of the developer. If foundation construction occurs during wet conditions, it is possible that
a geotextile fabric, placed between the bearing pad and native soils, will be necessary.
In general, before footing concrete is placed, any localized zones of loose soils exposed across the footing
subgrades should be compacted to a firm, unyielding condition, and any localized zones of soft, organic, or
debris-laden soils should be overexcavated and replaced with suitable structural fill.
Lateral Overexcavations: Because foundation stresses are transferred outward as well as downward into the
bearing soils, all structural fill placed under footings, should extend horizontally outward from the edge of each
footing. This horizontal distance should be equal to the depth of placed fill. Therefore, placed fill that extends
24 inches below the footing base should also extend 24 inches outward from the footing edges.
Subgrade Observation: All footing subgrades should consist of firm, unyielding, native soils, or structural fill
materials that have been compacted to a density of at least 95 percent (based on ASTM:D-1557). Footings
should never be cast atop loose, soft, or frozen soil, slough, debris, existing uncontrolled fill, or surfaces
covered by standing water.
Bearing Pressures: In our opinion, for static loading, footings that bear on a properly prepared subgrade, or
structural fill bearing pads can be designed for a preliminary allowable soil bearing pressure of 2,000 psf. A
one-third increase in allowable soil bearing capacity may be used for short-term loads created by seismic or
wind related activities.
Footing Settlements: Assuming that structural fill soils are compacted to a medium dense or denser state, we
estimate that total post-construction settlements of properly designed footings bearing on properly prepared
subgrades will not exceed 1 inch. Differential settlements for comparably loaded elements may approach
one-half of the actual total settlement over horizontal distances of approximately 50 feet.
April 16, 2015 E3RA, Inc.
T15034 / Totenham, LLC – 701 Sunset Blvd NE, Renton Geotechnical Engineering Report
8
Footing Backfill: To provide erosion protection and lateral load resistance, we recommend that all footing
excavations be backfilled on both sides of the footings and stemwalls after the concrete has cured. Either
imported structural fill or non-organic onsite soils can be used for this purpose, contingent on suitable moisture
content at the time of placement. Regardless of soil type, all footing backfill soil should be compacted to a
density of at least 90 percent (based on ASTM:D-1557).
Lateral Resistance: Footings that have been properly backfilled as recommended above will resist lateral
movements by means of passive earth pressure and base friction. We recommend using an allowable passive
earth pressure of 250 psf for and an allowable base friction coefficient of 0.35 for site soils.
4.3 Slab-On-Grade Floors
In our opinion, soil-supported slab-on-grade floors can be used if the subgrades are properly prepared. We
offer the following comments and recommendations concerning slab-on-grade floors.
Floor Subbase: We recommend over-excavation of slab-on-grade floor subgrades to a minimum depth of 4 ½
feet. Slab-on-grade floors should either be constructed on undisturbed native soils or on properly compacted
structural fill as a floor subbase. If floor construction occurs during wet conditions, it is likely that a geotextile
fabric, placed between the structural fill floor subbase and native soils, will be necessary.
All subbase fill should be compacted to a density of at least 95 percent (based on ASTM:D-1557).
Capillary Break and Vapor Barrier: To retard the upward wicking of moisture beneath the floor slab, we
recommend that a capillary break be placed over the 12 inch subbase. Ideally, this capillary break would
consist of a 4-inch-thick layer of pea gravel or other clean, uniform, well-rounded gravel, such as “Gravel
Backfill for Drains” per WSDOT Standard Specification 9-03.12(4), but clean angular gravel can be used if it
adequately prevents capillary wicking. In addition, a layer of plastic sheeting (such as Crosstuff, Visqueen, or
Moistop) should be placed over the capillary break to serve as a vapor barrier. During subsequent casting of
the concrete slab, the contractor should exercise care to avoid puncturing this vapor barrier.
4.4 Asphalt Pavement
Since asphalt pavements will be used for the new driveway and parking areas, we offer the following
comments and recommendations for pavement design and construction.
Subgrade Preparation: After removal of any surficial sod, topsoil, or organic-rich fill, all soil subgrades should
be thoroughly compacted, then proof-rolled with a loaded dump truck or heavy compactor. Any localized
zones of yielding subgrade disclosed during this proof-rolling operation should be over excavated to a
maximum depth of 12 inches and replaced with a suitable structural fill material. All structural fill should be
compacted according to our recommendations given in the Structural Fill section. Specifically, the upper 2 feet
of soils underlying pavement section should be compacted to at least 95 percent (based on ASTM D-1557),
and all soils below 2 feet should be compacted to at least 90 percent.
Pavement Materials: For the base course, we recommend using imported crushed rock, such as "Crushed
Surfacing Top Course” per WSDOT Standard Specification 9-03.9(3). If a subbase course is needed, we
recommend using imported, clean, well-graded sand and gravel such as “Ballast” or “Gravel Borrow” per
WSDOT Standard Specifications 9-03.9(1) and 9-03.14, respectively.
April 16, 2015 E3RA, Inc.
T15034 / Totenham, LLC – 701 Sunset Blvd NE, Renton Geotechnical Engineering Report
9
Conventional Asphalt Sections: A conventional pavement section typically comprises an asphalt concrete
pavement over a crushed rock base course. We recommend using the following conventional pavement
sections:
Minimum Thickness
Pavement Course Parking Areas Driveways
Asphalt Concrete Pavement 2 inches 3 inches
Crushed Rock Base 4 inches 6 inches
Granular Fill Subbase (if needed) 6 inches 8 inches
Compaction and Observation: All subbase and base course material should be compacted to at least 95 percent
of the Modified Proctor maximum dry density (ASTM D-1557), and all asphalt concrete should be compacted
to at least 92 percent of the Rice value (ASTM D-2041). We recommend that an E3RA representative be
retained to observe the compaction of each course before any overlying layer is placed. For the subbase and
pavement course, compaction is best observed by means of frequent density testing. For the base course,
methodology observations and hand-probing are more appropriate than density testing.
Pavement Life and Maintenance: No asphalt pavement is maintenance-free. The above described pavement
sections present our minimum recommendations for an average level of performance during a 20-year design
life; therefore, an average level of maintenance will likely be required. Furthermore, a 20-year pavement life
typically assumes that an overlay will be placed after about 10 years. Thicker asphalt and/or thicker base and
subbase courses would offer better long-term performance, but would cost more initially; thinner courses
would be more susceptible to “alligator” cracking and other failure modes. As such, pavement design can be
considered a compromise between a high initial cost and low maintenance costs versus a low initial cost and
higher maintenance costs.
4.5 Structural Fill
The term "structural fill" refers to any material placed under foundations, retaining walls, slab-on-grade floors,
sidewalks, pavements, and other structures. Our comments, conclusions, and recommendations concerning
structural fill are presented in the following paragraphs.
Materials: Typical structural fill materials include clean sand, gravel, pea gravel, washed rock, crushed rock,
well-graded mixtures of sand and gravel (commonly called "gravel borrow" or "pit-run"), and miscellaneous
mixtures of silt, sand, and gravel. Recycled asphalt, concrete, and glass, which are derived from pulverizing
the parent materials, are also potentially useful as structural fill in certain applications. Soils used for structural
fill should not contain any organic matter or debris, nor any individual particles greater than about 6 inches in
diameter.
Fill Placement: Clean sand, gravel, crushed rock, soil mixtures, and recycled materials should be placed in
horizontal lifts not exceeding 8 inches in loose thickness, and each lift should be thoroughly compacted with a
mechanical compactor.
Compaction Criteria: Using the Modified Proctor test (ASTM:D-1557) as a standard, we recommend that
structural fill used for various onsite applications be compacted to the following minimum densities:
April 16, 2015 E3RA, Inc.
T15034 / Totenham, LLC – 701 Sunset Blvd NE, Renton Geotechnical Engineering Report
10
Fill Application Minimum
Compaction
Footing subgrade and bearing pad
Foundation backfill
Slab-on-grade floor subgrade and subbase
Asphalt pavement base
Asphalt pavement subgrade (upper 2 feet)
Asphalt pavement subgrade (below 2 feet)
95 percent
90 percent
95 percent
95 percent
95 percent
90 percent
Subgrade Observation and Compaction Testing: Regardless of material or location, all structural fill should be
placed over firm, unyielding subgrades prepared in accordance with the Site Preparation section of this report.
The condition of all subgrades should be observed by geotechnical personnel before filling or construction
begins. Also, fill soil compaction should be verified by means of in-place density tests performed during fill
placement so that adequacy of soil compaction efforts may be evaluated as earthwork progresses.
Soil Moisture Considerations: The suitability of soils used for structural fill depends primarily on their
grain-size distribution and moisture content when they are placed. As the "fines" content (that soil fraction
passing the U.S. No. 200 Sieve) increases, soils become more sensitive to small changes in moisture content.
Soils containing more than about 5 percent fines (by weight) cannot be consistently compacted to a firm,
unyielding condition when the moisture content is more than 2 percentage points above or below optimum.
For fill placement during wet-weather site work, we recommend using "clean" fill, which refers to soils that
have a fines content of 5 percent or less (by weight) based on the soil fraction passing the U.S. No. 4 Sieve.
5.0 RECOMMENDED ADDITIONAL SERVICES
Because the future performance and integrity of the structural elements will depend largely on proper site
preparation, drainage, fill placement, and construction procedures, monitoring and testing by experienced
geotechnical personnel should be considered an integral part of the construction process. Consequently, we
recommend that E3RA be retained to provide the following post-report services:
• Review all construction plans and specifications to verify that our design criteria presented in
this report have been properly integrated into the design;
• Prepare a letter summarizing all review comments (if required);
• Check all completed subgrades for footings and slab-on-grade floors before concrete is
poured, in order to verify their bearing capacity;
• Prepare a post-construction letter summarizing all field observations, inspections, and test
results (if required); and
701 Sunset Blvd NE
Renton, Washington
Topographic and Location Map
FIGURE 1
T15034
APPROXIMATE SITE
LOCATION
E3RA, Inc.
P.O. Box 44840
Tacoma, WA 98448
APPENDIX A
SOIL CLASSIFICATION CHART AND
KEY TO TEST DATA
LOG OF TEST PITS
CLAYEY GRAVELS, POORLY GRADED GRAVEL-SAND-CLAYMIXTURES
SILTS AND CLAYSCOARSE GRAINED SOILSMore than Half > #200 sieveLIQUID LIMIT LESS THAN 50
LIQUID LIMIT GREATER THAN 50
CLEAN GRAVELS
WITH LITTLE OR
NO FINES
GRAVELS WITH
OVER 15% FINES
CLEAN SANDS
WITH LITTLE
OR NO FINESMORE THAN HALF
COARSE FRACTION
IS SMALLER THAN
NO. 4 SIEVE
MORE THAN HALF
COARSE FRACTION
IS LARGER THAN
NO. 4 SIEVE
INORGANIC SILTS, MICACEOUS OR DIATOMACIOUS FINESANDY OR SILTY SOILS, ELASTIC SILTS
ORGANIC CLAYS AND ORGANIC SILTY CLAYS OF LOWPLASTICITY
OH
INORGANIC SILTS AND VERY FINE SANDS, ROCK FLOUR,SILTY OR CLAYEY FINE SANDS, OR CLAYEY SILTS WITHSLIGHT PLASTICITY
CH
SILTY GRAVELS, POORLY GRADED GRAVEL-SAND-SILT
MIXTURES
SANDS
SILTS AND CLAYS
Figure A-1
INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY,GRAVELLY CLAYS, SANDY CLAYS, SILTY CLAYS,LEAN CLAYS
E3RA
R-Value
Sieve Analysis
Swell Test
Cyclic Triaxial
Unconsolidated Undrained Triaxial
Torvane Shear
Unconfined Compression
(Shear Strength, ksf)
Wash Analysis
(with % Passing No. 200 Sieve)
Water Level at Time of Drilling
Water Level after Drilling(with date measured)
RV
SA
SW
TC
TX
TV
UC
(1.2)
WA
(20)
Modified California
Split Spoon
Pushed Shelby Tube
Auger Cuttings
Grab Sample
Sample Attempt with No Recovery
Chemical Analysis
Consolidation
Compaction
Direct Shear
Permeability
Pocket Penetrometer
CA
CN
CP
DS
PM
PP
PtHIGHLY ORGANIC SOILS
TYPICAL NAMES
GRAVELS
ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY,
ORGANIC SILTS
WELL GRADED GRAVELS, GRAVEL-SAND MIXTURES
MAJOR DIVISIONS
PEAT AND OTHER HIGHLY ORGANIC SOILS
WELL GRADED SANDS, GRAVELLY SANDS
POORLY GRADED SANDS, GRAVELLY SANDS
SILTY SANDS, POOORLY GRADED SAND-SILT MIXTURES
CLAYEY SANDS, POORLY GRADED SAND-CLAY MIXTURES
POORLY GRADED GRAVELS, GRAVEL-SAND MIXTURES
SOIL CLASSIFICATION CHART AND KEY TO TEST DATA
GW
GP
GM
GC
SW
SP
SM
SC
ML
FINE GRAINED SOILSMore than Half < #200 sieveLGD A NNNN02 GINT US LAB.GPJ 11/4/05INORGANIC CLAYS OF HIGH PLASTICITY, FAT CLAYS
CL
OL
MH
SANDS WITH
OVER 15% FINES
GB
S-1
GBS-2
GP
SM
SM
SM
0.5
3.5
4.5
7.5
(GP) Gray gravel with sand and some silt (medium dense, moist) (Gravel Surfacing)
(SM) Brown silty sand (medium dense, moist) (Fill)
(SM) Dark brown silty sand with logs, woody debris and general refuse (loose, moist) (Fill)
(SM) Light brown silty sand with some gravel (medium dense, moist) (Weathered Till)
No caving observed
No groundwater seepage observed
The depths on the test pit logs are based on an average of measurements across the test pit and should be considered
accurate to 0.5 foot.Bottom of test pit at 7.5 feet.
NOTES
GROUND ELEVATION
LOGGED BY DMW
EXCAVATION METHOD
EXCAVATION CONTRACTOR GROUND WATER LEVELS:
CHECKED BY
DATE STARTED 1/21/15 COMPLETED 1/21/15
AT TIME OF EXCAVATION ---
AT END OF EXCAVATION ---
AFTER EXCAVATION ---
TEST PIT SIZE
SAMPLE TYPENUMBERDEPTH(ft)0.0
2.5
5.0
7.5
TEST PIT NUMBER TP-1
PAGE 1 OF 1
Figure A-2
CLIENT Totenham, LLC
PROJECT NUMBER T15034
PROJECT NAME 701 Sunset Blvd NE
PROJECT LOCATION Renton, Washington
COPY OF GENERAL BH / TP LOGS - FIGURE.GDT - 4/3/15 16:53 - Z:\2015 JOB FILES\T15034 TOTENHAM, LLC - 701 NE SUNSET BLVD, RENTON GEOTECH\T15034 TEST PITS.GPJE3RA, Inc.
E3RA, Inc.
P.O. Box 44840
Tacoma, WA 98448
Telephone: 253-537-9400
Fax: 253-537-9401
U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION
GB
S-1
GBS-2
GP
SM
SM
SM
0.5
3.5
4.5
7.5
(GP) Gray gravel with sand and some silt (medium dense, moist) (Gravel Surfacing)
(SM) Brown silty sand (medium dense, moist) (Fill)
(SM) Dark brown silty sand with logs, woody debris and general refuse (loose, moist) (Fill)
(SM) Light brown silty sand with some gravel (medium dense, moist) (Weathered Till)
No caving observed
No groundwater seepage observed
The depths on the test pit logs are based on an average of measurements across the test pit and should be considered
accurate to 0.5 foot.Bottom of test pit at 7.5 feet.
NOTES
GROUND ELEVATION
LOGGED BY DMW
EXCAVATION METHOD
EXCAVATION CONTRACTOR GROUND WATER LEVELS:
CHECKED BY
DATE STARTED 1/21/15 COMPLETED 1/21/15
AT TIME OF EXCAVATION ---
AT END OF EXCAVATION ---
AFTER EXCAVATION ---
TEST PIT SIZE
SAMPLE TYPENUMBERDEPTH(ft)0.0
2.5
5.0
7.5
TEST PIT NUMBER TP-2
PAGE 1 OF 1
Figure A-3
CLIENT Totenham, LLC
PROJECT NUMBER T15034
PROJECT NAME 701 Sunset Blvd NE
PROJECT LOCATION Renton, Washington
COPY OF GENERAL BH / TP LOGS - FIGURE.GDT - 4/3/15 16:53 - Z:\2015 JOB FILES\T15034 TOTENHAM, LLC - 701 NE SUNSET BLVD, RENTON GEOTECH\T15034 TEST PITS.GPJE3RA, Inc.
E3RA, Inc.
P.O. Box 44840
Tacoma, WA 98448
Telephone: 253-537-9400
Fax: 253-537-9401
U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION
SM
SM
SM
0.5
3.5
4.5
7.5
Sod and Topsoil
(SM) Brown silty sand (medium dense, moist) (Fill)
(SM) Dark brown silty sand with logs, woody debris and general refuse (loose, moist) (Fill)
(SM) Light brown silty sand with some gravel (medium dense, moist) (Weathered Till)
No caving observed
No groundwater seepage observed
The depths on the test pit logs are based on an average of measurements across the test pit and should be considered
accurate to 0.5 foot.Bottom of test pit at 7.5 feet.
NOTES
GROUND ELEVATION
LOGGED BY DMW
EXCAVATION METHOD
EXCAVATION CONTRACTOR GROUND WATER LEVELS:
CHECKED BY
DATE STARTED 1/21/15 COMPLETED 1/21/15
AT TIME OF EXCAVATION ---
AT END OF EXCAVATION ---
AFTER EXCAVATION ---
TEST PIT SIZE
SAMPLE TYPENUMBERDEPTH(ft)0.0
2.5
5.0
7.5
TEST PIT NUMBER TP-3
PAGE 1 OF 1
Figure A-4
CLIENT Totenham, LLC
PROJECT NUMBER T15034
PROJECT NAME 701 Sunset Blvd NE
PROJECT LOCATION Renton, Washington
COPY OF GENERAL BH / TP LOGS - FIGURE.GDT - 4/3/15 16:53 - Z:\2015 JOB FILES\T15034 TOTENHAM, LLC - 701 NE SUNSET BLVD, RENTON GEOTECH\T15034 TEST PITS.GPJE3RA, Inc.
E3RA, Inc.
P.O. Box 44840
Tacoma, WA 98448
Telephone: 253-537-9400
Fax: 253-537-9401
U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION