16915 TALBOT RD.PDF16915 TALBOT RD
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ADDRESS: I Leq ( a I bo+ R
TAX ACCOUNT/PARCEL #: Lo�blDD ln7iDU
BUILDING PERMIT (NEW STRUCTURE) #:
COVENANTS (RECORDED) FOR:
CRITICAL AREAS #: DETERMINATION: ❑ Conditional Waiver ❑ Study Required ❑ Waiver
CRITICAL AREAS #: DETERMINATION: ❑ Conditional Waiver ❑ Study Required ❑ Waiver
DISCRETIONARY PERMIT #'S:
DRAINAGE PLAN DATED:
PARKING AGREEMENTS DATED:
EASEMENT(S) RECORD FOR:
PERMITS (OTHER — list permit #'s):
PLANNING DATA CHECKLIST DATED: �� ! ('
SCALED PLOT PLAN DATED: i D Q
SEWER LID FEE $:
LID #:
SHORT PLAT FILE:
LOT:
BLOCK:
SIDE SEWER AS BUILT DATED:
SIDE SEWER PERMIT(S) #:
GEOTECH REPORT DATED: ZQ 2 d
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STREET USE/ENCROACHMENT PER IT #:
FOR:
WATER METER TAP CARD DATED:
OTHER:
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Certi ' ate ofOccupancy
DEPARTMENT OF BUILDINGS .1
PER INTERNAL� ZONAL RESIDENTIAL CODE SECTION R110
AT: 16915 TALBOT ROAD EDMONDS WA 98026' - ,Building Perm, it #:. BLD20090316
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Occupancy established by this certificate: R3 _. Dwelling Units:7-5
1
No, Stories: 2 Basement: NIA R- Type of.Constr�uction: VB
Owner of building: PHILIP & DIANA TIEGS
The Single Family Residence at 16915 TALBOTJRDi has:been inspected and approved complying with the requirements
of the 2006 edition of the International Residential Code as-Naddopte d by theme City f the group and division of occupancy and the use for which
the proposed occupancy is classified.
Issued this 26TH day of August, 2010
Chief Buildinct_Official
By:
STREET FILE
Any change of occupancy or use requires a building permit and.1a new Certificate o"ccupancy issued by the City of Edmonds Building Official.
T:
Drainage Report for s Residence
16915 Talbot Drive, Edmonds, WA 98025
September 8, 2009
Page 1 of 4
STREET FILE
Dat�Iall
DRAINAGE NARRATIVE
TIEGS RESIDENCE
16915 TALBOT DRIVE
EDMONDS, WA .98025
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Norman & Norman Desivners — Box 1052 — Lawlev. WA 98260 — (360) 381-0061
1
Drainage Report for As Residence
16915 Talbot Drive, Edmonds, WA 980.25
September 8, 2009
Page 2 of 4
PROJECT SUMMARY
E
This project consists of removal of existing habitable house and construction of new house at 16915
Talbot Drive (formerly 16911 Talbot), Edmonds, Washington, 98025. The existing lot is 16,158.6
square foot and belongs to Phil and Diana Tiegs. The existing topography remains and will remain
largely unaltered. The terrain consists of a moderately steep drive leading from Talbot Drive (which
bounds the western property line), then along the north property line to an existing building pad in the
central knoll, and bounded by a steep ravine sloping east along the eastern property line.
The previous house (now demolished August 2009) was built in approximately 1973. The terrain
preceding 1973 is assumed to be largely consistent with current topography with the exception of
minor cuts to provide the driveway on the north side and building pad on the central knoll area.
Given the site has a small knoll, no drainage from other properties enters this site. The drainage on the
eastern property line is and has always drained to the east and is not modified in any substantial
amount. Therefore, it is not considered in any drainage modifications or proposals.
The soils are generally considered Whidbey Till and consist of sand, silt, clay and lenses of gravel. A
Preliminary Geotechnical Engineering Evaluation was requested and prepared by Nelson Geotechnical -
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Norman & Norman Desicyners — Box 1052 — 1_angleu W,4
98260 — (360) 381-0061
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Drainage Report for As Residence
16915 Talbot Drive, Edmonds, WA 98025
September 8, 2009
Page 3 of 4
Associates in May of 2008 and is included by reference as Appendix A.
Construction of new residence will consist of minor grading to sculpt area for new footing and minor
reshape of driveway footprint. Also planned is the addition of a Rain Garden Detention Feature as
shown on accompanying Drainage Plans and drawings by Norman & Norman Designers.
The existing project consists of 3,719 sf of impervious driveway and 2,507 sf of roof dripline (now
removed) for a total of 6,225 sf existing impervious. The new project will reuse portions of the
existing driveway with overlays as needed. The portion of existing driveway removed and not reused
is approximately 2,240 sf, which does not reflect in any drainage calculations. The project will have
1,589 sf in new footprint driveway and 3,309 sf in new roof dripline for a total of 4,898 sf.
RAIN GARDEN DESIGN
The Rain Garden Detention Feature was selected as the favorable option to detain surface waters
because of its perceived lower impact to existing conditions. The topography is split est/west by an
existing rockery which serves the driveway. This break in topography makes it impractical to catch a
portion surface waters on the western portion of the parcel that are below the height of the entrance to
the proposed Rain Garden. These surface waters are 1,253 sf of driveway and 1,447 of existing
landscaped area. These surface waters have and will continue to flow to the existing city storm drain.
Or
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Norman & Norman Deshmers — Box 1052 — I_anvlev. TV
98260 — (360) 381-0061
Drainage Report for Residence
16915 Talbot Drive, Edmonds, WA 98025
September 8, 2009
Page 4 of 4
All surface waters above the Rain Garden entrance height are captured by an Overlay Surface Divertor
(speed bump) and by a Vegetation Lined Drainage Ditch as shown on the referenced Drainage Plan by
Norman & Norman Designers.
The areas impacting the Rain Garden are the roof dripline of 3,309 sf and the area of driveway of 1,514
sf. (new and existing) that are above the Overlay Surface Divertor (speed bump). Additionally, an area
of 6,846sf of existing permeable landscaping below and beside the new residence (counted as Forest,
moderate) will drain into the Rain Garden Detention Feature. These mitigated areas impacting the Rain
Garden are delineated in the Area Drainage Quantities Site Plan and are attached as Appendix B and
have been modeled in the Western Washington Hydrology Modeling software (WWHM3 version 1.0).
The WWHM3 data output in attached as Appendix D. The pervious Mitigated areas are summarized as
6,846 sf (0.157163 acres) of Forest moderate. The impervious Mitigated areas are summarized as
1,514 sf (0.034757 acres) of Roads moderate and 3,309 sf (0.075964 acres) of Roof tops flat. The Rain
Garden therefore serves an area of 4,823 sf of impervious surfaces.
The predevelopment areas modeled in WWHM3 for Forest flat, Forest moderate and Forest steep are
delineated in the Predevelopment Areas Site Plan, attached as Appendix C. The Predevelopment areas
are summarized as 1,514 sf (0.034757 acres) of Forest flat, 6,846 sf (0.157163 acres) of Forest
moderate and 3,309 sf (0.075964 acres) of Forest steep.
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Norman & Norman Designers — Box .1052 — Lancyleu WA 98260 — (360) 381-0061
PRELIMINARY GEOTECHNICAL
ENGINEERING EVALUATION
TIEGS RESIDENCE
EDMONDS, WASHINGTON
PREPARED FOR
MR. PHIL TIEGS
NELSON tEO'4'EChINICAL
ASSOCIATES, INC.
GEOT'ECl- LAICAL ENGINEERS & GEOLOGIST'S
Main Office
17311 —135`h Avenue NE, A-500
Woodinville, WA 98072
(425) 486-1669 FAX (425) 481-2510
(425) 337-1669 Snohomish County
May 12, 2008
Mr. Phil Tiegs
16911 Talbot Road
Edmonds, Washington 98261
Preliminary Geotechnical Engineering Evaluation
Tiegs Residence
Edmonds, Washington
NGA File No. 787108
Dear Mr. Tiegs:
Engineering -Geology Branch
437 East Penny Road
Wenatchee, WA 98801
(509) 665-7696. FAX (509) 665-7692
We are pleased to submit the attached report titled "Preliminary Geotechnical Engineering Evaluation —
Tiegs Residence — Edmonds, Washington." This report summarizes the existing surface and subsurface
conditions within the site and provides recommendations for the proposed site development. Our services
were completed in general accordance with the proposal signed by you on March 31, 2008.
The site is currently occupied by a single-family residence and associated driveway. Final development
plans were not available at the time this report was prepared. It is our understanding that the planned
improvements will include the removal of the existing structure and construction of a new single-family
residence. A steep east -facing slope is located east of the property.
We monitored the excavation of two test pits on the property. We have concluded that the, site is
generally compatible with the planned development. We have recommended that the new structure and
retaining wall be bu^,ded on medium dense or better granular native soil for bearing capacity and
settlement considerations. Our explorations indicated that the site is underlain by glacial soils. Also, the
site slope appears to be stable. However, there is a potential for shallow sloughing and erosion events to
occur on the steep slope. We recommend that the new residence be set back at least 30 feet from the
existing steep slope. In the attached report, we have included recommendations for site grading,
foundation support, and site drainage.
We recommend that NGA be retained to review the geotechnical aspects of the project plans prior to
construction. We recommend that NGA be retained to provide monitoring and consultation. services
during construction to confirm that the conditions encountered are consistent with those indicated by the
explorations, to provide recommendations for design changes should the conditions revealed during the
work differ from those anticipated, and to evaluate whether or not earthwork and foundation installation
activities comply with contract plans and specifications.
Preliminary Geotel'cal Engineering Evaluation •
Tiegs Residence
May 12, 2008
NGA File No. 787108
Summary - Page 2
We appreciate the opportunity to provide service to you on this project. Please contact us if you have any
questions regarding this report or require further information.
Sincerely,
NELSON GEOTECHNICAL ASSOCIATES, INC.
Khaled M. Shawish, PE
Principal
Three Copies Submitted
• •
TABLE OF CONTENTS
INTRODUCTION......................................................................................................................................1
SCOPE......................................................................................................................................................... 1
SITECONDITIONS.................................................................................................................................. 2
SURFACECONDITIONS.............................................................................................................................. 2
SUBSURFACECONDITIONS................................................:....................................................................... 2
HYDROLOGIC CONDITIONS....................................................................................................................... 3
SENSITIVE AREA EVALUATION........................................................................................................ 3
SEISMICHAZARD.....................:................................................................................................................
3
EROSIONHAZARD.....................................................................................................................................
4
LANDSLIDE HAZARD/SLOPE STABILITY .................. :................................................................................
4
CONCLUSIONS AND RECOMMENDATIONS................................................................................... 5
GENERAL...................................................................................................................................................
5
EROSION CONTROL AND SLOPE PROTECTION MEASURES........................................................................
6
SITE•PREPARATION AND GRADING..................:........................................................................................
7
STRUCTURESETBACKS.............................................................................................................................
7
TEMPORARYSLOPES.................................................................................................................................
8
FOUNDATIONS...........................................................................................................................................
9
STRUCTURALFILL..................................................................................................................................
10
SLAB-ON-GRADE....................................................................................................................................
I 1
PAVEMENTSUBGRADE...........................................................................................................................
11
SITEDRAINAGE.......................................................................................................................................
11
USE OF THIS REPORT.............................................................:................................:........................... 12
LIST OF FIGURES
Figure 1 —Vicinity Map
Figure 2 — Site Plan
Figure 3 — Cross-section A -A'
Figure 4 Soil Classification Chart
Figures 5 — Test Pit Logs
NELSON GEO TECHNICAL ASSOCIATES, INC.
0
•
Preliminary Geotechnical Engineering Evaluation
Tiegs Residence
Edmonds, Washington
INTRODUCTION
This report presents the results of our geotechnical engineering investigation and evaluation of the
planned Tiegs Residence in Edmonds, Washington. The project site is located at 16911 Talbot Road as
shown on the Vicinity Map in Figure 1. The purpose of this study is to explore and characterize the site's
surface and subsurface conditions and to provide geotechnical recommendations for site development.
For our use in preparing this report, we have been provided with a site plan titled "Tiegs — Boundary and
Topographic Survey," prepared by Peterson Consulting Engineers, dated January 7, 2008.
The site is currently occupied by an existing residence. The planned improvements will include the
removal of the existing residence and the construction of a new residence. A steep east -facing slope is
located along the eastern property line. Final development plans were not available at the time this report
was prepared. The current site layout is shown on the Site Plan in Figure 2.
SCOPE
The purpose of this study is to explore and characterize the site surface and subsurface conditions, and
provide general recommendations for site development. Specifically, our scope of services includes the
following:
Explore the subsurface soil and groundwater conditions within the site with backhoe-
excavated test pits. The backhoe was subcontracted by NGA.
2.. Map the conditions on the slope and evaluate current slope stability conditions.
3. Perform iaboratory classification and analysis of soil samples, as necessary.
4. Provide general recommendations for earthwork, foundation support, and slabs -on -grade.
5. Provide general recommendations for pavement subgrade preparation.
6. Provide general recommendations for site drainage and erosion control.
7. Document the results of our findings, conclusions, and recommendations in a written
preliminary geotechnical report.
NELSON GEOTECHN/CAL ASSOCIATES, INC.
Preliminary Geotelecal Engineering Evaluation •
Tiegs Residence
May 12, 2008 .
NGA File No. 787108
Page 2
SITE CONDITIONS
Surface Conditions
The property is an irregular -shaped parcel covering approximately 0.35-acre. The site consists of a
relatively level pad along the top of a steep east -facing slope and is occupied by a single-family residence.
Pavement and lawn areas surround the residence with landscaping plants and a few scattered immature
deciduous trees. The property is bordered to the north and south by residential properties, to the east by_
the steep slope, and to the west by the Talbot Road.
The steep east -facing slope is vegetated with mature trees, blackberries, and underbrush. Most of the
trees on the steep slope appeared to be straight, with a few observed to be slightly bent down slope. We
measured a slope inclination of approximately 38 degrees (78 percent), as shown on Cross-section A -A'
in Figure 3. This steep slope is approximately 85 feet in height. We did not observe surface water on the
site or seepage on the slope during our site visit on April 18, 2008. We did not observe signs of recent
slope movement.
Subsurface Conditions
Geology: The geologic units for this area are shown on the Geologic Map of the Edmonds East and Part
of. the Edmonds West Quadrangle, Washington, by James P. Minard (USGS, 1983). The site is mapped
as Till (Qvt) with the Whidbey Formation (Qw) mapped in close proximity to the site. The till is
described as a non -sorted mixture of clay, silt, sand, pebbles, cobbles; and boulders. The Whidbey
Formation is described as bedded sand, silt and clay with lenses of gravel. Our explorations generally
encountered silty fine to medium sand and sand soils generally consistent with the description of the .
Whidbey Formation.
Explorations: The subsurface conditions within the site were explored on April 18,. 2008 by excavating
two test pits to the depth of 11.0 feet below the existing ground surface using a backhoe. The
approximate locations of our explorations are shown .on the Site Plan in Figure 2. A geologist from
Nelson Geotechnical Associates, Inc. (NGA) was present during the explorations, examined the soils and
geologic conditions encountered, obtained samples of the different soil types, and maintained logs of the
test pits.
NELSON GEOTECHN/CAL ASSOCIATES, INC.
Preliminary Geoteecal Engineering Evaluation
Tiegs Residence
May 12, 2008
NGA File No. 787108
Page 3
The soils were visually classified in general accordance with the Unified Soil Classification System,
presented in Figure 4. The logs of our test pits are attached to this report and are presented as Figure 5.
We present a brief summary of the subsurface conditions in the following paragraph. For a detailed
description of the subsurface conditions, the test pits logs should be reviewed.
Both of our explorations encountered a surficial layer of sod to approximately 0.3 feet. Underlying the
sod, Test Pit 1 encountered approximately 2.2 feet of light brown, stiff, silt with trace fine to medium
sand and gravel that we interpreted to be undocumented fill. Below the fill in Test Pit 1 and below the
grass in Test Pit 2, we encountered approximately 1.0 to 2.2 feet of brown, medium dense to dense, fine
to medium sand with silt and gravel, underlain by light brown to gray, dense, silty fine sand and fine sand
with silt. We interpreted these soils to be Whidbey Formation deposits. Test Pit I and 2 were terminated
within the Whidbey Formation deposit at a depth of 11.0 feet below the existing ground surface.
Hydrologic Conditions
Groundwater seepage was not encountered in either of the test pits. However, it is possible that perched
groundwater conditions could occur on this site during extended periods of wet weather. Perched water
occurs when surface water infiltrates through less dense, more permeable soils and accumulates on top of
a lower permeability material. Perched water does not represent a regional groundwater "table" within
the upper soil horizons. .Perched water tends to vary spatially and is dependent upon the amount of
rainfall. We would expect the amount of perched water to decrease during drier times of the year and
increase during wetter periods if perched water were to develop on this site.
SENSITxVE AREA 'E"VALI)JA T ION
Seismic Hazard
We reviewed the 2006 International Building Code (IBC) for seismic site classification for this project.
Since medium dense to dense sand and silty sand deposits were encountered underlying the site, the site
conditions best fit the IBC description for Site Class D.
Hazards associated with seismic activity include liquefaction potential and amplification of ground
motion by soft deposits. .Liquefaction is caused by a rise in pore pressures in a loose, fine sand deposit
beneath the groundwater table. The medium dense to dense silty sand interpreted to underlie the site has
a low potential for liquefaction or amplification of ground motion.
NELSON GEOTECHN/CAL ASSOCIA TES, INC.
Preliminary Geote0cal Engineering Evaluation •"
Tiegs Residence
May 12, 2008
NGA File No. 787108
Page 4
The dense soils interpreted to form the core of the site slope are considered stable with respect to deep-
seated slope failures. However, the loose surficial materials on the slope have the potential for shallow
sloughing failures during. seismic events. Such events should not affect the planned structure provided the
foundations are designed with the setback from the slope .as described in the Foundations and Structure
Setback subsections of this report.
Erosion Hazard
The criteria used for determination of erosion hazard areas include soil type, slope gradient, vegetation
cover, and groundwater conditions. The erosion sensitivity is related to vegetative cover and the specific
surface soil types, which are related to the underlying geologic soil units. The Soil Survey of Snohomish
County Area,'Washington, by the Soil Conservation Service (SCS) was reviewed to determine the erosion
hazard of the on -site soils. The site surface soils were classified using the SCS classification system as
Alderwood-Urban land complex, 2 to 8 percent slopes, and Alderwood-Urban land complex, 8 to 15
percent slopes. These units are listed as having a slight erosion hazards. We anticipated that the surficial
soils on the steeper portions of the slope would have moderate to high erosion potential if stripped of
vegetation. .
Landslide Hazard/Slope Stability
The criteria used for evaluation of landslide hazards include soil type, slope gradient, and groundwater
conditions. A steep west -facing slope with a gradient of up to approximately 38 degrees (78 percent) with
a height of approximately 85 feet is located below the planned development area. We did not observe
evidence of past erosion or sloughing on this slope during our site visit. We did not observe seepage on
the slopes during our visit. Most of the mature trees on the steep;slope appeared to be straight, with a few
observed to be slightly bowing down slope.
The"_core of the slope is inferred to consist primarily of dense native soils. Inclinations of up to 38
degrees on the slope indicate high strength and internal friction angle within the underlying soils.
Relatively shallow sloughing failures as well as surficial erosion are natural processes and should be
expected on these slopes. It is our opinion that while there is potential for erosion, soil creep, and shallow
failures within the loose surficial soils on the steep slope; there is not a significant potential for deep-
seated slope failure under current site conditions. Proper site grading and drainage as well as adequate
NELSON GEOTECHN/CAL ASSOCIATES, INC.
Preliminary Geotscal Engineering Evaluation •
Tiegs Residence
May 12, 2008
NGA File No. 787108
Page 5
setback distances and foundation placement as recommended in this report should help maintain current
stability conditions.
CONCLUSIONS AND RECOMMENDATIONS
General
It is our opiriion that the planned development is feasible from a geotechnical standpoint, provided that
our recommendations are incorporated into the design and construction of this project. The steep eastern
slope is considered stable with respect to deep-seated failures. However, there is a potential for shallow
sloughing and erosion events to occur on the slope. We anticipate that during periods of extended rainfall
and/or as a result of seismic activity, shallow slough -type failures may occur on the slopes. This report is
preliminary in nature and is intended to provide general opinions regarding geotechnical
recommendations for site grading and earthwork. We should be retained to review the project plans prior
to construction.
We recommend that the planned residence have a minimum setback of 30 feet from the top of the steep
slope. The structure setback will lessen the impacts of the proposed development on the slope and allow
for normal slope recession during a reasonable life span of the structure. This is further discussed in the
Structure Setback subsection of this report.
The residence foundations could be designed as conventional spread footings. These footings should
extend through any loose surficial soil or undocumented fill and be founded on. the underlying medium
dense or better native soils or structural fill.extending to these soils. Based on our exploration, medium
dense soils should, typically be encountered approximately ,,vo to three feet below the existing sux aCe;
however, thicker areas of loose soil or fill may be encountered in unexplored areas of the site.
The surficial soils encountered on this site are considered moisture -sensitive and.may disturb easily when
wet. To lessen the potential impacts of construction on the steep slope.and to -reduce cost overruns and
delays, we recommend that construction take place during the drier summer. months if possible. If
construction takes place during the rainy months, additional expenses and delays should -be expected.
These extra expenses could include additional erosion control and temporary drainage measures to protect
the slope, placement of a blanket of rock spalls to protect exposed subgrades, and the need for importing
all-weather materials for structural fill.
NELSON GEOTECHN/CAL ASSOCIATES, INC.
Preliminary Geotmical Engineering Evaluation .
Tiegs Residence
May 12, 2008
NGA File No. 787108
Page 6
Under no circumstances should water be allowed to flow over, or concentrate on the., slope; both during
construction and after construction has been completed. We recommend that stormwater runoff from the
roof drains, paved areas, and yard drains be collected and tightlined to a suitable discharge point away
from the steep slope. The slope should be protected from erosion. We recommend that all disturbed
areas be replanted to re-establish vegetation as soon as possible. The steep slope should not be disturbed
or graded. Fill and stockpiled materials should not be placed, on the slope or within the set back areas.
Stormwater runoff, should not be allowed to concentrate or flow over . the slope. Specific
recommendations for erosion control are presented in the Erosion Control and Slope Protection
Measures subsection of this report.
Erosion Control and Slope Protection Measures
The erosion hazard for the on -site soils is interpreted to be slight in the flat areas and moderate to high on
the steep slope east of the site, but the actual hazard will be dependent on how the site is graded and how
water is allowed to concentrate. Best Management Practices (BMPs) should be used to control erosion.
Areas disturbed during construction should be protected from erosion. Erosion control measures may
include diverting surface water away from the stripped or disturbed areas. Silt fences and/or straw bales
should be erected to prevent muddy water from leaving the site or flowing over the steep slope.
Stockpiles should be covered with plastic sheeting during wet weather and stockpiled material should be
placed no closer than 30 feet from the top of the slope. Disturbed areas should be planted as soon as
practical and the vegetation should be maintained until it is established. The erosion potential for areas
not stripped of vegetation should be low.
Protection of the steep slope and setback areas should be perfo.r ed as required by the City of Edmonds.
Specifically, we recommend that the setback area and steep slope not be disturbed or modified through
placement of any fill or removal of the existing vegetation. No material of any kind should be placed on
the slope.or be allowed to reach the slope, such as excavation spoils, lawn clippings, and other yard waste,
trash, or soil stockpiles. Trees should not be cut down or .removed from the steep slope unless a
mitigation plan is developed, such as the replacement of vegetation for erosion protection. Replacement
of vegetation should be performed. in accordance with the City of Edmonds code. Any proposed
development within the slope setback area, other than light decks or patios, should be the subject of a
specific geotechnical evaluation. Under no circumstances should water be allowed to concentrate on the
slope.
NELSON GEOTECHN/CAL ASSOCIATES, INC.
Preliminary Geotelecal Engineering Evaluation •
Tiegs Residence
May 12, 2008
NGA File No. 787108
Page 7
Site Preparation and Grading
Final grading plans were not available at the time this report was prepared. After erosion control
measures are implemented, site preparation should consist of stripping any loose soils or undocumented
fill to expose medium dense or better native soil in foundation, slab -on -grade, and pavement areas. The
stripped materials should be removed from the site or stockpiled for later use as landscaping fill.
Stockpiles should be covered with plastic sheeting during wet weather and stockpiled material should be
placed no closer than 30 feet from the top of the slope.
If the exposed subgrade soil should appear to be loose, it should be compacted to a non -yielding
condition. Areas observed to pump or weave during compaction should be over -excavated and replaced
with properly compacted structural fill or rock spalls. If loose soils are encountered in the pavement
areas,. the loose soils should be removed and replaced with rock spalls or granular structural fill. If
significant surface water flow is encountered during construction, this flow should be diverted around
areas to be developed, and the exposed subgrades should be maintained in a semi -dry condition.
If wet conditions are encountered, alternative site stripping and grading techniques might be necessary.
These could include using large excavators equipped with wide tracks and a smooth bucket to complete
site grading and covering exposed subgrade with a layer of crushed rock for protection. If wet conditions
are encountered or construction is attempted in wet weather, the subgrade should not be compacted as this
could cause further subgrade disturbance. In wet conditions it may be necessary to cover the exposed
subgrade with a layer of crushed rock as soon as it is exposed to protect the moisture sensitive soils from
disturbance by machine_ or. foot traffic during construction. The prepared subgrade should be protected
from construction traffic and surface water should be diverted around prepared subgrade.
Structure Setbacks
Uncertainties related to building along steep slopes are typically addressed by the use of building
setbacks. The purpose of the setback is to establish a "buffer zone" between the structure and the top of
the slope so that ample room is allowed for normal slope recession during a reasonable life span of the
structure. In a general sense, the greater the setback distance, the lower the risk of slope failures
impacting the structure. From a geological standpoint, the setback dimension is based on the slope's
physical characteristics, such as slope height, surface angle, material composition, and hydrology. Other
NELSON GEOTECHN/CAL ASSOCIA TES, INC.
Preliminary GeotAlical Engineering Evaluation •
Tiegs Residence
May 12, 2008
NGA File No. 787108
Page 8
factors such as historical slope activity, rate of regression, and the type and desired life span of the
development are important considerations as well.
We recommend that structures be set back at least 30 feet from the top of the eastern steep slope. It is our
opinion that this setback is adequate for the planned residence. The downslope (east) footing line of the
residence should be embedded at least three feet into medium dense or better native soil.
We should be retained to evaluate the residence foundation setback distances and subgrade soil prior to
placing foundation forms. Any proposed development within the setback area, other than light decks or
patios, should be the subject of a specific geotechnical evaluation. Under no circumstances should water
be allowed to concentrate on the slopes, during or after construction.
Temporary Slopes
Temporary cut slope stability is a function of many factors, including the type and consistency of soils,
depth of the cut, surcharge loads adjacent to the excavation, length of time a cut remains open, and the
presence of surface water or groundwater. It is exceedingly difficult under these variable conditions to
estimate a stable, temporary, cut slope angle. Therefore, it should be the responsibility of the contractor
to maintain safe slope configurations since he is continuously at the job site, able to observe the soil and
groundwater conditions encountered and able to monitor the nature and condition of the cut slopes.
The following information is provided solely for the benefit of the owner and other design consultants and
should not be construed to imply that Nelson Geotechnical Associates, Inc. assumes responsibility for job
site safety. job site safety is the sole resporsibility;of the project contractor.
For planning purposes, we recommend that temporary cuts in the on -site soils be no steeper than 2
Horizontal to 1 Vertical (2H:1V). If significant groundwater seepage or surface water flow were
encountered, we would expect that flatter inclinations would be necessary.. We recommend that cut
slopes be protected from erosion. The slope protection measures may include covering cut slopes with
plastic sheeting and diverting surface runoff away from the top of cut slopes. We do .not recommend
vertical slopes for cuts deeper than four feet, if worker access is necessary. We recommend that cut slope
heights and inclinations conform to appropriate OSHA/WISHA regulations.
NELSON GEOTECHN/CAL ASSOCIATES, INC.
Preliminary Geotocal Engineering Evaluation •
Tiegs Residence
May 12, 2008
NGA File No. 787108
Page 9
Foundations
Conventional shallow spread foundations should be placed on undisturbed medium dense or better native
soils, or be supported on structural fill extending to those soils. Where undocumented fill or less dense
soils are encountered at the planned footing elevation, the subgrade should be over -excavated to expose
suitable bearing soil. The over -excavation may be filled with structural fill, or the footing may be
extended down to the bearing native soils. If. footings are supported on structural fill, the fill zone should
extend outside the edges of the footing a distance equal to at least one-half of the thickness of the fill
placed below the bottom of the footing.
Footings, including interior footings, should extend at least 18 inches below the lowest adjacent finished
ground surface .for frost protection and bearing capacity considerations.. The downhill footing lines
should be deepened to satisfy the effective setback requirement. Foundations should be designed in
accordance with the 2006 International Building Code (IBC). Footing widths should be based on the
anticipated loads and allowable soil bearing pressure. Water should not be allowed to accumulate in
footing trenches. All loose or disturbed soil should be removed from the foundation excavation prior to
placing concrete.
For foundations constructed as outlined above, we recommend an allowable design bearing pressure of
not more than 2,000 pounds per square foot (psf) be used for the design of foundations supported on the
medium dense or better native soils or structural fill extending to the competent native soils. A
representative of NGA should evaluate the foundation bearing soil. We should be consulted if higher
bearing pressures are needed. Current IBC guidelines should be used when considering increased
allowable bearing pressure for short-term transitory wind or seismic loads. Potential foundation
settlement using the recommended allowable bearing .pressure is estimated to be less than one -inch total
and 'h-inch differential between adjacent footings or across a distance of about 30 feet based on our
experience with similar projects. `
Lateral loads may be resisted by friction on the base of the footing and passive resistance against the
subsurface portions of the foundation. A coefficient of friction of.0.35 may be used to calculate the base
friction and should be applied to the vertical dead load only. Passive resistance may be calculated as a
triangular equivalent fluid pressure distribution. An equivalent fluid density of 200 pounds per cubic foot
(pcf) should be used for passive resistance design for a level ground surface adjacent to the footing. This
NELSON GEOTECHN/CAL ASSOCIATES, INC.
Preliminary Geotecal Engineering Evaluation 0
Tiegs Residence
May 12, 2008
NGA File No. 787108
Page 10
level surface should extend a distance equal to at least three times the footing depth. These recommended
values incorporate safety factors of 1.5 and 2.0 applied to the estimated ultimate values for frictional and
passive resistance, respectively. To achieve this value of passive resistance, the foundations should be
poured "neat" against the native medium dense soils or compacted fill should be used as backfill against
the footing. We recommend that the upper one -foot of soil be neglected when calculating the passive
resistance.
Structural Fill
General: Fill placed beneath foundations, pavement, or other settlement -sensitive structures should be
placed as structural fill. Structural fill, by definition, is placed in accordance with prescribed methods and
standards, and is monitored by an experienced geotechnical professional or, soils technician. Field
monitoring procedures would include the performance of a representative number of in -place density tests
to document the attainment of the desired degree of relative compaction. The area to receive the fill
should be suitably prepared as described in the Site Preparation and Grading subsection prior to
beginning fill placement.
Materials: Structural fill should consist of a good quality, granular soil, free of organics and other
deleterious material, and be well graded to a maximum size of about three inches. All-weather structural
fill should contain no more than five -percent fines (soil finer than U.S. No. 200 sieve, based on that
fraction passing the U.S. 3/4-inch sieve). The use of the on -site soils as structural fill may be feasible but
will be dependent on moisture content of the material at the time construction takes place. We should be
retained to evaluate proposed structural fill material prior to placement.
Fill Placement: Following subgrade preparation, placement of structural fill may proceed. All filling
should be accomplished in uniform lifts up to eight inches thick. Each lift should be spread evenly and be
thoroughly compacted prior to placement of subsequent lifts. All structural fill should be compacted to a
minimum of 95 percent of its maximum dry density. Maximum dry density, in this report, refers to that
density as determined by the ASTM D-1557 Compaction Test procedure. The moisture content of the
soils to be compacted should be within about two percent of optimum so that a readily compactable
condition exists. It may be necessary to over -excavate and remove wet soils in cases where drying to a
compactable condition is not feasible. All compaction should be accomplished by equipment of a type
and size sufficient to attain the desired degree of compaction.
NELSON GEOTECHN/CAL ASSOCIA TES, INC.
Preliminary Geot4bical Engineering Evaluation •
Tiegs Residence
May 12, 2008
NGA File No. 787108
Page 11
Slab -on -Grade
Slabs -on -grade should be supported on subgrade soils prepared as described in the Site Preparation and
Grading subsection of this report. We recommend that all floor slabs be underlain by at least six inches
of free -draining gravel with less than three percent by weight of the material passing Sieve 4200 for use
as a capillary break. We recommend that the capillary break be hydraulically connected to the footing
drain system to allow free drainage from under the slab. A suitable vapor barrier, such as heavy plastic
sheeting (6-mil minimum), should be placed over the capillary break material. An additional 2-inch thick
moist sand layer may be used to cover the vapor barrier. This sand layer is optional and is intended to
protect the vapor barrier membrane during construction.
Pavement Subgrade
Pavement subgrade preparation and structural filling where required, should be completed as
recommended in the Site Preparation and Grading and Structural Fill subsections of this report. The
resulting surface should be proof -rolled under a loaded dump truck. Areas observed to pump or weave
during the proof -roll test should be over -excavated and replaced with structural fill or rock spalls to
prepare a stable subgrade prior to placing the pavement base course. We should be retained to observe
the proof -rolling and recommend repairs prior to placement of the asphalt or hard surfaces.
Site Drainage
Surface.Drainage: Final site grades should allow for drainage away from the top of the steep slope and
away from the planned residence. We suggest that the finished ground be sloped at a minimum gradient
of three percent for a distance of at least 10 feet away from the building and top of slope. Runoff
generated on this site should be collected and routed into a permanent discharge system. This should
include all downspouts and runoff generated on all hard surfaces and :yards areas. Under no
circumstances should water be allowed to flow uncontrolled over the slope. Water should not be allowed
to collect in any area where footings, slabs, or pavements are to be constructed.
Subsurface Drainage: If groundwater is encountered during construction, we recommend that the
contractor slope the bottom of the excavation and collect the water into ditches and small sump pits where
the water can be pumped out of the excavation and routed into a suitable outlet.
NELSON GEOTECHN/CAL ASSOCIATES, INC.
Preliminary Geotsical Engineering Evaluation
Tiegs Residence
May 12, 2008
NGA File No. 787108
Page 12
We recommend the use of footing drains around structures and behind retaining walls. Footing drains
should be installed at least one foot below planned finished floor elevation. The drains should consist of a
minimum four -inch -diameter, rigid, slotted or perforated,'PVC pipe surrounded by free -draining material
wrapped in a filter fabric. We recommend that the free -draining material consist of an 18-inch-wide zone
of clean (less than three -percent fines), granular material placed along the back of walls. Washed rock is
an acceptable drain material, or drainage composite may be used instead. The free -draining material
should extend up the wall to one -foot below the finished surface. The top foot of soil should consist of
low permeability soil placed over plastic sheeting or building paper to minimize the migration of surface
water or silt into the footing drain. Footing drains should discharge into tightlines leading to an
appropriate collection and discharge point with convenient cleanouts to prolong the useful life of the
drains. Roof drains should not be connected to wall or footing drains.
USE OF THIS REPORT
NGA has prepared this preliminary report for Mr. Phil Tiegs and his agents for use in the planning and
design of the development planned on this site only. The scope of our work does not include services
related to construction safety precautions and our recommendations are not intended to direct the
contractors' methods, techniques, sequences, or procedures, except as specifically described in our report
for consideration in design. There are possible variations in subsurface conditions between the
explorations and also with time. Our report, conclusions, and interpretations should not be construed as a
warranty of subsurface conditions. A contingency for unanticipated conditions should be included in the
budget and schedule.
The scope of our work does not include services related to conkruction safety precautions and our
recommendations are not intended to direct the contractors' methods, techniques, sequences, or
procedures, except as specifically described in our report for consideration in design. There are possible
variations in subsurface conditions between the explorations and also with time. Our report, conclusions,
and interpretations should not be construed as a warranty of subsurface conditions. A contingency for
unanticipated conditions should be included in the budget and schedule. This report is preliminary in
nature. We recommend that we review final plans to determine that our recommendations have been
incorporated into project plans.
NEL SON GEO TECHNICAL A SSOCIA TES, INC.
Preliminary Geoteical Engineering Evaluation •
Tiegs Residence
May 12, 2008
NGA File No. 787108
Page 13
We recommend that NGA be retained to provide monitoring and consultation services during
construction to confirm that the conditions encountered are consistent. with those indicated by the
explorations, to provide recommendations for design changes should the conditions revealed during the
work differ from those anticipated, and to evaluate whether or not earthwork and foundation installation
activities comply with contract plans and specifications. We should be contacted a minimum of one week
prior to construction activities and could attend pre -construction meetings if requested.
All people who own or occupy homes on hillsides should realize that landslide movements are always a
possibility. The landowner should periodically inspect the slope, especially after a winter storm. If
distress is evident, a geotechnical engineer should be contacted. for advice on remedial/preventative
measures. The probability that landsliding will occur is substantially reduced by the proper maintenance
of drainage control measures at the site (the runoff from the roofs should be led to an approved discharge
point). Therefore, the homeowner should take responsibility for performing such maintenance.
Consequently, we recommend that a copy of our report be provided to any future homeowners of the
property if the home is sold.
Within the limitations of scope, schedule, and budget, our services have been performed in accordance
with generally accepted geotechnical engineering practices in effect in this area at the time this report was
prepared. No other warranty, expressed or implied, is made. Our observations, findings, and opinions are
a means to identify and reduce the inherent risks to the owner.
NELSON GEOTECHN/CAL ASSOCIATES, INC.
Preliminary Geoteical Engineering Evaluation .
Tiegs Residence
May 12, 2008
NGA File No. 787108
Page 14
We appreciate the opportunity to provide service to you on this project. If you have any questions or
require further information, please call.
Sincerely,
NELSON GEOTECHNICAL ASSOCIATES, INC.
Lee Bellah J
Staff Geologist
Michael D. Rundquist, PE
Senior Engineer
BD:LSB:MDR:pkw
r
Five Figures Attached.
NELSON GEOTECHN/CAL ASSOCIATES, INC.
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GEOTECHNICAL ENGINEERS & GEOLOGISTS
No.
Date
Revision
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NOTES:
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0
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1)
Stratigraphic conditions are interpolated between
Geologic Contact
(approximate) 2)
Reference: Cross Section is based on field measurements using a hand-held clinometer and 100-ft tape measure.
the explorations. Actual conditions may vary.
Elevations are arbitrary.
N
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NGA Drafting 2008V87108
Tiegs\CS.dwo
III
UNIFIED SOIL CLASSIFICATION SYSTEM
GROUP
MAJOR DIVISIONS
GROUP NAME
SYMBOL
CLEAN
GW
WELL -GRADED, FINE TO COARSE GRAVEL
COARSE-
GRAVEL
-
GRAVEL
GP
POORLY -GRADED GRAVEL
GRAINED
MORE THAN 50 %
GRAVEL
GM
SILTY GRAVEL
OF COARSE FRACTION
RETAINED ON
SOILS
NO. 4SIEVE
WITH FINES
GC
CLAYEY GRAVEL
SAND
CLEAN
SW
WELL -GRADED SAND, FINE TO COARSE SAND
SAND
SP
POORLY GRADED SAND
MORE THAN 50 %
RETAINED ON
MORE THAN 50 %
NO. 200 SIEVE
OF COARSE FRACTION
SAND
SM
SILTY SAND
PASSES NO. 4 SIEVE
WITH FINES
SC
CLAYEY SAND
FINE -
SILT AND CLAY
ML
SILT
INORGANIC
GRAINED
LIQUID LIMIT
CL
CLAY
LESS THAN 50 %
SOILS
ORGANIC
OL
ORGANIC SILT, ORGANIC CLAY
SILT AND CLAY
MH
SILT OF HIGH PLASTICITY, ELASTIC SILT
INORGANIC
MORE THAN 50
PASSES
LIQUID LIMIT
CH
CLAY OF HIGH PLASTICITY, FLAT CLAY
NO. 200 SIEVE
50 % OR MORE
ORGANIC
OH
ORGANIC CLAY, ORGANIC SILT
HIGHLY ORGANIC SOILS
PT
PEAT
NOTES:
1) Field classification is based on visual
SOIL MOISTURE MODIFIERS:
examination of soil in general
accordance with ASTM D 2488-93.
Dry - Absence of moisture, dusty, dry to
the touch
2) Soil classification using laboratory tests
is based on ASTM D 2488-93.
Moist - Damp, but no visible water.
3) Descriptions of soil density or
Wet - Visible free water or saturated,
consistency are based on
usually soil is obtained from
interpretation of blowcount data,
below water table
visual appearance of soils, and/or
I
test data.
e
Project Number
/�
N\7 ELSON EOTECHNICAL
No.
Date
Revision
By
n
CK e
787108
Tiegs Residence
Soil Classification Chart
, �° em ASSOCIATES INC.
f -
GEOTECHNICAL ENGINEERS & GEOLOGISTS
,
4/28/08
Original
SLS
BD �
Figure 4
.
17311-135m Ave. NE, A 50D
VJootlimtlle, — 66072
Snonom'M Coun17 (425) 337-1868
WemlcMelCM - (506):5.7696
C
(4251466-1 1 Fea 481-2510
xvm.ml:ngeomtll.wm
LOG OF EXPLORATIOP
DEPTH (FEET) USC SOIL DESCRIPTION
TEST PIT ONE
0.0 - 0.3
0.3 - 2.5
2.5 - 3.5
3.5 - 11.0
TEST PIT TWO
0.0 - 0.3
0.3 - 2.5
2.5 - 6.5
6.5 - 11.0
SLS: BD
SOD
ML LIGHT BROWN, SILT WITH TRACE FINE TO MEDIUM SAND AND GRAVEL (STIFF, MOIST) (FILL)
SP-SM BROWN, FINE TO MEDIUM SAND WITH SILT AND GRAVEL (MEDIUM DENSE, MOIST)
SP LIGHT BROWN TO GRAY, FINE SAND (DENSE, MOIST)
SAMPLES WERE COLLECTED AT 2.0, 3.5, 6.0, AND 9.5 FEET
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
TEST PIT CAVING WAS NOT ENCOUNTERED
TEST PIT WAS COMPLETED AT 11.0 FEET ON 4/18/08
SOD
SP-SM BROWN, FINE TO. MEDIUM SAND WITH SILT AND GRAVEL (DENSE, MOIST)
SM LIGHT BROWN, SILTY FINE SAND (DENSE, MOIST)
SP-SM GRAY, FINE SAND WITH SILT.AND SILT LAYERS (DENSE, MOIST) .
(DENSE, MOIST)
SAMPLES WERE COLLECTED AT 1.5, 3.0, 5.0, 7.0 AND 10.0 FEET
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
TEST PIT CAVING WAS NOT ENCOUNTERED
TEST PIT WAS COMPLETED AT 11.0 FEET ON 4/18/08
NELSON GEOTECHNICAL ASSOCIATES, INC.
FILE NO 787108
FIGURE 5
w
Of
0
0
O
m
J
Q
F-
TRENCH DRAIN DIVERTING
DRAINAGE TO RAIN GARDE
" AREA DRAINA A U „ PT SITE PLAN
APPENDIX'S'
IMPERVIOUS CALCULATIONS:
EXISTING IMPERVIOUS DRIVEWAY/PAVED AREAS: 3,11E SF.
EXISTNG ROOF DRIPLINE AREAS: 2301 SF
TOTAL EXISTING IMPERVIOUS AREAS: 025 SF.
NEW ROOF DRIPLNE: 3-" SF.
NEW DRIVEWAY AREA: IBM 9F.
TOTAL (NEW CONSTRUCTION) IMPERVIOUS: 4,8W SF.
RAIN GARDEN CALCULATIONS:
EXISTMiMW IMPERVIOUS DRIVEWAY: 1,514 SF.
NEW ROOF DRIPLNE AREAS: 3305 gF
TOTAL IMPERMOUS AREAS SERVED: 4,813 SF.
TOTAL PERMEABLE SURFACE:. (PA46 SF.
SIZNG OF RAN GARDEN (USING WWHM MODELNG
SOFTWAM
REQUIRED VOLUME OF IIFILTRATNG POND:
0.0155 ACRE-FEET (5,181 gal)
PROVIDED SIZE OF RAN GARDEN: 5J81 gal
0
•
" PREDEVELOPMENT AREA SITE PLAN
SCALE: 1 "=20.00'
APPENDIX'C'
/A ANOT�
IMPAC ING RAID
/, GA EN
821 + 96 6 sf =;
///, 1.789.
1 AREA OF
I\ FOREST FLAT
=1,514 sf
IMPERVIOUS CALCULATIONS:
EXISTNG IMPERVIOUS DRIV 11AYMAVED AREAS: 3,119 OF.
EXISTNG ROOF DRIPLNE AREAS: 2W1 OF
TOTAL EXISTNG IMPERVIOUS AREAS:
6�25 Of.
NEW ROOF ORIPLNE:
3,309 Sr-.
NEW DRIVEWAY AREA:
1589 3F.
TOTAL (NEW GCNSTRUCTION) IMPERVIOUS:
4A98 Of.
RAIN GARDEN CALCULATIONS:
EXISTINWNEW.IMPERVIOUS DRIVEWAY:
1,514 OF.
NEW ROOF DRIPLNE AREAS:
3305 gF
TOTAL IMPERVIOUS AREAS SERVED:
4,023 OF.
TOTAL PERMEA5LE SURFACE:
SUNG OF RAN GARDEN
6046 OF.
WONG WIIW MODELNG
OQFRUARE
RECLARED VOLUME OF NFILTRATNG POND:
OA59 ACRE-FEET (5,181 gall
PROVIDED SIZE OF RAN GARDEN:
5,181 gal
0
0
.Q
a
•
•
�ue6t
0.0101
87
2115
2431
Fail
0.0102
85
2083
2450
Fail
0.0103
81
2056
2538
Fail
0.0104
81
2026
2501
Fail
0.0105
77
1997
2593
Fail
0.0106
77
1971
2559
Fail
0.0107
75
1942
2589
Fail
0.0108
73
1903
2606
Fail
0.0110
69
1880
2724
Fail
0.0111
67
1852
2764
Fail
0.0112
65
1821
2801
Fail
0.0113
63
1790
2841
Fail
0.0114
61
1756
2878
Fail
0.0115
61
1718
2816
Fail
0.0116
60
1693
2821
Fail
0.0117
59
1668
2827
Fail
0.0118
59
1635
2771
Fail
0.0120
59
1611
2730
Fail
0.0121
58
1577
2718
Fail
0.0122
57
1546
2712
Fail
0.0123
57
1522
2670
Fail
0.0124
56
1497
2673
Fail
0.0125
54
1459
2701
Fail
0.0126
53
1422
2683
Fail
0.0127
53
1399
2639
Fail
0.0128
53
1372
2588
Fail
0.0130
52
1349
2594
Fail
0.0131
51
1321
2590
Fail
0.0132
51
1301
2550
Fail
The development has an increase in flow durations
from 1/2 predeveloped 2 year flow to the 2 year flow
or more than a 10% increase from the 2 year to the 50
year flow.
Water Quality BMP.Flow and Volume for POC 1.
On-line facility volume: 0 acre-feet
On-line facility target flow: 0 cfs.
Adjusted for 15 min: 0 cfs.
Off-line facility target flow: 0 cfs.
Adjusted for 15 min: 0 cfs.
Perind and Impind Changes
No changes have been made.
OED BY
ENGINEERING
STREET FILE
This program and accompanying documentation is provided 'as -is' without warranty of any kind. The
entire risk regarding the performance and results of this program is assumed by the user. Clear Creek
Solutions and the Washington State Department of Ecology disclaims all warranties, either expressed or
implied, including but not limited to implied warranties of program and accompanying documentation. In
no event shall Clear Creek Solutions and/or the Washington State Department of Ecology be liable for
any damages whatsoever (including without limitation to damages for loss of business profits, loss of
business information, business interruption, and the like) arising out of the use of, or inability to
use this program even if Clear Creek Solutions or the Washington State Department of Ecology has been
advised of the possibility of such damages.
Tiegs Residence Drainage WWHM3 Data (09/15/09) R ES U B
Appendix D SEP 2 3 2009
Page 8 of 8
BUILDING DSPAR7WNT
CITY OF MMONDS
•
•
0.0040
898
6013
669
Fail
0.0041
825
5893
714
Fail
0.0042
776
5786
745
Fail
0.0043
715
5687
795
Fail
0.0044
661
5545
838
Fail
0.0045
626
5442
869
Fail
0.0046
588
5339
907•
Fail
0.0047
552
5240
949
Fail
0.0049
527
5137
974
Fail
0.0050
491
5030
1024
Fail
0.0051
458
4935
1077
Fail
0.0052
428
4836
1129
Fail
0.0053
406
4729
1164
Fail
0.0054
378
4647
1229
Fail
0.0055
354
4557
1287
Fail
0.0056
326
4471
1371
Fail
0.0057
309
4364
1412
Fail.
0.0058
288
4300
1493
Fail
0.0060
270
4210
1559
Fail
0.0061
263
'4119
1566
Fail
0.0062
247
4026
1629
Fail
0.0063
240
3950
1645
Fail
0.0064
230
3858
1677
Fail
0.0065
223
3789
1699
Fail
0.0066
214
3712
1734
Fail
0.0067
205
3662
1786
Fail
0.0068
199
3591
1804
Fail
0.0070
188
3526
1875
Fail
0.0071
171
3462
2024
Fail
0.0072
161
3382
2100
Fail
0.0073
152
3313
2179
Fail
0.0074
146
3237
2217
Fail
0.0075
135
3172
2349
Fail
0.0076
130
3107
2390
Fail.
0.0077
126
3049
2419
Fail
0.0078
124
2989
2410
Fail
0.0080
121
2935
2425
Fail
0.0081
119
2870
2411
Fail
0.0082
117
2823
2412
Fail
0.0083
114
2762
2422
Fail
0.0084.
113
2725
2411
Fail
0.0085
ill
.2671
2406
Fail
0.0086
109
2624
2407
Fail
0.0087
108
2581
2389
Fail
0.0088
106
2546
2401
Fail
0.0090
104
2506
2409
Fail
0.0091
103
2469
2397
Fail
0.0092
100
2430
2430
Fail
0.0093
100
2387
2387
Fail
0.0094
99
2340
2363
Fail
0.0095
95
2299
2420
Fail
0.0096
95
2260
2378
` Fail
0.0097
93
2224
2391
Fail
0.0098
89
2185
2455
Fail
0.0100
89
2149
2414
Fail
Tiegs
Residence Drainage WWHM3 Data (09/15/09)
Appendix D
Page 7 of 8
•
18
0.0047
0.0064
19
0.0046
0.0064
20
0.0045
0.0063
21
0.0045
0.0062
22
0.0044
0.0061
23
0.0042
0.0061
24
0.0042
0.0060
25
0.0042
0.0060
26
0.0041
0.0059
27
0.0041
0.0058
28
0.0041
0.0058
29
0.0041
0.0058
30
0.0040
0.0057
31
0.0040
0.0057
32
0.0040
0.0056
33
0.0038
0.0055
34
0.0037
0.0055
35
0.0037
0.0054
36
0.0036
0.0053
37
0.0035
0.0052
38
0.0034
0.0051
39
0.0033
0.0050
40
0.0033
0.0048•
41
0.0032
0.0047
42
0.0032
0.0045
43
0.0032
0.0044
44
0.0032
0.0044
45
0.0024
0.0043
46
0.0023
0.0040
47
0.0022
0.0035
48
0.0019
0.0033
49
0.0014
0.0022
POC #1
Facility FAILED duration standard for 1+ flows.
Flow(CFS) Predev Dev Percentage Pass/Fail
0.0022
3521
8144
231
Fail
0.0023
3210
8006
249
Fail
0.0024
2949
7783
263
Fail
0.0025
2704
7620
281
Fail
0.0026
2506
7469
298
Fail
0.0027
2299
7349
319
Fail
0.0029
2107
7203
341
Fail
0.0030
1920
7066
368
Fail
0.0031
1753
6924
394
Fail
0.0032
1608
6821
424
Fail
0.0033
1478
6722
454
Fail
0.0034
1357
6606
486
Fail
0.0035
1248
6477
518
Fail
0.0036
1144
6387
558
Fail
0.0037
1060
6263
590
Fail
0.0039
978
6155
629
Fail
Tiegs Residence Drainage WWHM3 Data (09/15/09)
Appendix D
Page 6 of 8
1965
0.004
0.006
1966
0.004
0.005
1967
0.002
0.004
1968
0.006
0.007
1969
0.006
0.008
1970
0.004
0.005
1971
0.003
0.005
1972
0.005
0.006
1973
0.005
0.007
1974
0.003
0.004
1975
0.004
0.006
1976
0.003
0.004
1977
0.003
0.007
1978
0.002
0.006
1979
0.003
0.004
1980
0.010
0.008
1981
0.004
0.005
1982
0.004
0.004
1983
0.004
0.007
1984
0.004
0.006
1985
0.004
0.006
1986
0.006
0.007
1987
0.015
0.011
1988
0.006
0.008
1989
0.003
0.005
1990
0.005
0.002
1991
0.004
0.006
1992
0.004
0.006
1993
0.004
0.005
1994
0.002
0.005
1995
0.002
0.005
1996
0.004
0.006,
1997
0.009
0.008
1998
0.019
0.012
Ranked Yearly Peaks for Predeveloped and Mitigated.
Rank
Predeveloped
Mitigated
1
0.0186
0.0123
2
0.0150
0.0114
3
0.0102
0.0084
4
0.0087
0.0083
5
0.0083
0.0082
6
0.0076
0.0078
7
0.0073
0.0078
8
0.0068
0.0075
9
0.0063
0.0072
10
0.0062
0.0071
11
0.0061
0.0070
12
0.0061
0.0069
13
0.0060
0.0067
14
0.0059
0.0067
15
0.0056
0.0067
16
0.0050
0.0066
17
0.0048
0.0066
POC #1
Tiegs Residence Drainage WWHM3 Data (09/15/09)
Appendix D
Page 5 of 8
•
2.700
0.021
0.029
0.304
0.008
2.733
0.021
0.030
0.380
0.008
2.767
0.022
0.031
0.461
0.008
2.800
0.022
0.032
0.548
0.008
2.833
0.022
0.032
0.639
0'.008
2.867
0.023
0.033
0.735
0.008
2.900
0.023
0.034
0.836
0.008
2.933
0.023
0.035
0.941
0.008
2.967
0.023
0.035
1.050
0.008
3.000
0.024
0.036
1.163
0.008
3.033
0.024
0.037
1.280
0.009
MITIGATED LAND USE
ANALYSIS RESULTS
Flow Frequency Return Periods for Predeveloped. POC #1
Return Period
Flow(cfs)
2 year
0.004374
5 year
0.006644
10 year
0.008421
25 year
0.010998
50 year
0.013173
100 year
0.015578
Flow Frequency Return Periods for Mitigated. POC #1
Return Period
Flow(cfs)
2 year
0.005997
5 year
0.00754
10 year
0.008409
25 year
0.009376
50 year
0.010017
100 year
0.010602
Yearly Peaks for Predeveloped and Mitigated. POC #1
Year
Predeveloped
Mitigated
1950
0.001
0.006
1951
0.007
0.006
1952
0.003
0.006
1953
0.003
0.004
1954
0.004
0.003
1955
0.006
0.005
1956
0.008
0.008
1957
0.006
0.006
1958
0.008
0.007
1959
0.006
0.007
1960
0.005
0.007
1961
0.004
0.007
1962
0.004
0.007
1963
0.004
0.006
1964
0.007
0.006
Tiegs Residence Drainage WWHM3 Data (09/15/09)
Appendix D
Page 4 of 8
s
•
0.867
0.007
0.004
0.000
0.003
0.900
0.007
0.004
0.000
0.003
0.933
0.008
0.004
0.002
0.003
0.967
0.008
0.005
0.003
0.003
1.000
0.008
0.005
0.003
0.003
1.033
0.008
0.005
0.004
0.003
1.067
0.009
0.006
0:004
0.003
1.100
0.009
0.006
0.005
0.003
1.133
0.009
0.006
0.005
0*003
1.167
0.009
0.006
0.005
0.003
1.200
0.010
0.007
0.006
0.003
1.233
0.010
0.007
0.006
0.003
1.267
0.010
0.007
0.006
0.004
1.300
0.010
0.008
0.007
0.004
1.333
0.010
0.008
0.007
0.004
1.367
0.011
0.008
0.007
0.004
1.400
0.011
0.009
0.007
0.004
1.433
0.011,
0.009
0.008
0.004
1.467
0.011
0.010
0.008
0.004
1.500
0.012
0.010
0.008
0.004
1.533
0.012
0.010
0.008
0.004
1.567
0.012
0.011
0.009
0.004
1.600
0.012
0.011
0.009
0.004
1.633
0.013
0.012
0.009
0.004
1.667
0.013
0.012
0.009
0.005
1.700
0.013
'0.012
0.009
0.005
1.733
0.013
0.013
0.010
0.005
1.767
0.014
0.013
0.010
0.005
1.800
0.014
0.014
0.010
0.005
1.833
0.014
0.014
0.010
0.005
1.867
0.014
0.015
0.010
0.005
1.900
0.015
0.015
0.010
0.005
1.933
0.015
0.016
0.011
0.005
1.967
0.015
0.016
0.011
0.005
2.000
0.015
0.017
0.011
0.005
2.033
0.016
0.017
0.011
0.006
2.067
0.016
0.018
0.011
0.006
2.100
0.016
0.018
0.011
0.006
2.133
0.016
0.019
0.012
0.006
2.167
0.017
0.019
0.012
0.006
2.200
0.017
0.020
0.012
0.006
2.233
0.017
0.020
0.012
0.006
2.267
0.017
0.021
0.012
0.006
2.300
0.018
0.022
0.012
0.006
2.333
0.018
0.022
'0.012
0.006
2.367
0.018
0.023
0.013
0.007
2.400
0.019
0.023
0.013
0.007
2.433
0.019
0.024
0.013
0.007
2.467
0.019
0.025
0.013
0.007
2.500
0.019
0.025
0.013
0.007
2.533
0.020
0.026
0.033
0.007
2.567
0.020
0.027
0.069
0.007
2.600
0.020
0.027
0.116
0.007
2.633
0.021
0.028
0.172
0.007
2.667
0.021
0.029
0.235
0.007
Tiegs Residence Drainage WWHM3 Data (09/15/09)
Appendix D
Page 3 of 8
0 •
Name Trapezoidal Pond 1
Bottom Length: 58.5ft.
Bottom Width: 1.5ft.
Depth 3ft.
Volume at riser head 0.0253ft.
Infiltration On
Infiltration rate 0.25
Infiltration saftey factor 1
Wetted surface area On
Side slope 1: 2 To 1
Side slope 2: 2 To 1
Side slope 3: 2 To 1
Side slope 4: 4 To 1
Discharge Structure
Riser Height: 2.5 ft.
Riser Diameter: 4 in.
Orifice 1 Diameter: 0.63 in. Elevation: 0.9 ft.
Element Flows To:
Outlet 1 Outlet 2
Pond
Hydraulic
Table
Staae(ft)
Area(acr)yolume(acr-ft)
Dschra(cfs)
Infilt(cfs)
0.000
0.002
0.000
0.000
0.000
0.033
0.002
0.000
0.000
0.001
0.067
0.002
0.000
0.000
0.001
0.100
0.003
0.000
0.000
0.001
0.133
0.003
-0.000
0.000
0.001
0.167
0.003
0.000
0.000
0.001
0.200
0.003
0.001
0.000
0.001
0.233
0.003
0.001
0.000
0.001
0.267
0.004
0.001
0.000
0.001
0.300
0.004
0.001
0.000
0.001
0.333
0.004
0.001
0.000
0.001
0.367
0.004
0.001
0.000
0.001
0.400
0.004
0.001
0.000
0.001
0.433
0.005
0.001
0.000
0.001
0.467
0.005
0.002
0.000
0.002
0.500
0.005
0.002
0.000
0.002
0.533
0.005
0.002
0.000
0.002
0.567
0.005
0.002
0.000
0.002
0.600
0.006
0.002
0.000
0.002
0.633
0.006
0.002
0.000
0.002
0.667
0.006
0.003
0.000
0.002
0.700
0.006
0.003
0.000
0.002
0.733
0.006.
0.003
0.000
0.002
0.767
0.007
0.003
0.000
0.002
0.800
0.007
0.003
0.000
0.002
0.833
0.007
0.004
0.000
0.002
Tiegs Residence Drainage WWHM3 Data (09/15/09)
Appendix D
Page 2 of 8
0
U
Western Washington Hydrology Model
PROJECT REPORT
Project Name: Tiegs Rain Garden-8
Site Address: 16911 Talbot Drive
City Edmonds
Report Date 09/17/09
Gage Everett
Data Start 1948/10/01
Data End 1997/09/30
Precip Scale: 0.80
WWHM3 Version:
PREDEVELOPED LAND USE
Name
Basin 1
Bypass: No
GroundWater:
No
Pervious Land Use
Acres
C, Pasture,
Flat
.034757
C, Pasture,
Mod
.157163
C, Pasture,
Steep
.075964
Impervious Land Use
Acres
Element Flows To:
Surface Interflow Groundwater
Name Basin 1
Bypass: No
GroundWater: No
Pervious Land Use
Acres
C, Pasture, Mod
.157163
Impervious Land Use
Acres
ROADS MOD
0.034757
ROOF TOPS FLAT
0.075964
Element Flows To:
Surface Interflow Groundwater
Trapezoidal'Pond 1, Trapezoidal Pond 1,
Tiegs Residence Drainage WWHM3 Data (09/15/09)
Appendix D
Page 1 of 8
TN
+'[•lib�,i''
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