HomeMy WebLinkAboutBLD2012-00382 Geotechnical Report t.
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GEOTECHNICAL SITE REVIEW & RECOMMENDATIONS
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Prepared For Quinten Shay
April 3, 2012
For the Property Described As
Parcel Number 721194012
Section 19,Township 27 North, Range 1 East, W.M.
Jefferson County, Washington
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Prepared by D'
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Harriet S. Cornachione, MSc, LG
Robert A. Leach, PE -
JEFFERSON COUNTY
DEPT.OF COMMUNITY DEVELOPMENT
NTI ENGINEERING &SURVEYING, INC.
717 S. Peabody Street
Port Angeles, Washington 98362
Phone 360.452.8491 Fax 360.452.8498
Web Site www.nti4u.com
E-mail info @nti4u.com
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GEOTECHNICAL REVIEW & SITE RECOMMENDATIONS
Prepared For Quinten Shay
April 3, 2012
For the Property Described As
Parcel Number 721194012
Section 19,Township 27 North, Range 1 East, W.M.
Jefferson County, Washington
Prepared By
NTI ENGINEERING & LAND SURVEYING
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Harriet S. Cornactione _
Harriet S.Cornachione, MSc, LG Robert A. Leach, MBA, PE
Project Geologist Principal Engineer
2
1.0 Introduction
A geotechnical site review has been completed at the above referenced property,at the request of the property
owner to identify any specific geologic or geotechnical concerns and to provide appropriate guidelines and
recommendations for site development. It is our understanding that the site is to be developed with an accessory
dwelling unit (ADU). The site is covered by the Critical Area and Shoreline regulations of Jefferson County Code
Section 18.22 and 18.25, respectively. The shoreline is classified as "conservancy"and the parcel has been
identified with areas of landslide hazard, shoreline stability and erosion hazard in the Jefferson County GIS.The
parcel is zoned Rural Residential 1:5.
The scope of the investigation included a geotechnical site reconnaissance field investigation, performed on
February 24, 2012, review of the septic test pit exposures and soil logs,and research and review of available public
records of neighboring parcels,the Washington Coastal Zone Atlas, U.S. Department of Agriculture Natural
Resources Conservation Service Soils Maps and geologic mapping of the area through Washington Department of
Natural Resources.
2.0 Site Description
The parcel is located on Groves Way Road,east of Thorndyke Road, and can be accessed off of Highway 104 via
South Point Road. The parcel (see Figure 1) is an irregularly shaped, long narrow lot extending approximately 1400
feet in length north—south, and ranging in width from approximately 90 feet to 300 feet east—west. It has been
developed with an existing 2-bedroom home located north of Groves Way. The remainder of the property is
undeveloped, moderately to heavily forested and generally well vegetated with trees and abundant understory.
Figure 1. Parcel location map showing topographic contours at 10 foot intervals.(Source:Jefferson County GIS)
The northern portion of the undeveloped property slopes gently to the southeast at approximately 7—10%. The
southern half of the parcel is a steep bluff sloping to the Hood Canal shoreline, ranging from slopes of 50%to
approximately 90%. The steep bluff to the south ranges in elevation from sea level to approximately 300 feet at the
top of slope to the north. Significant slope breaks occur along the bluff at approximately 80—100 feet, 140—150
feet and 200—240 feet,where slopes flatten to approximately 20%—45%. A narrow winding foot path provides
beach access across the bluff face.
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Trees located in the northern property, in the vicinity of the proposed development are generally in good condition,
vertical and healthy(see Figure 2). No visible evidence of soil movement or slope instability was observed in this
area of the property.
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Figure 2. Site photograph looking south,showing typical vertical stature of trees in vicinity of septic test pit.
Slopes to the south contain abundant alder trees,which can often be found in areas of slope instability(see Figure 3).
Generally these trees exhibit good vertical trunks,with some areas of jackstrawed development. Understory is less well
developed along the bluff areas,with some soil and rock exposures along the steeper slopes.
Figure 3. View along bluff slope showing typical vegetation in upper bench vicinity.
3.0 Site Geology&Soils
The site contains bedrock geologic units deposited during Pleistocene glaciation episodes. The upper 2/3 of the
parcel is mapped as Vashon Till,commonly referred to as Lodgemont Till.This unit typically consists of a largely
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unstratified mix of clay,silt,sand and gravels deposited by glaciers during the Vashon stade. Within the property
this unit is mapped,and was observed.on site in exposures along the upper slopes to the south,generally above
approximately 100 feet in relief. The tll overlies stratified sediments mapped as pre-Vashon in age(Geologic Map
of East Jefferson County). Till unit(hardpan)was encountered in Soil Test Pit#1 at a depth of 57 inches. Figure 4
(below)shows an exposure of the stratified sediments below the till unit.
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Figure 4. View along bluff slope showing section of stratified sediments,alternating silts and gravel layers.
As mapped by the National Resources Conservation Service (NRCS)site soils are identified primarily as Alderwood
gravelly,sandy loam. This soil is typically formed on terraces overlying basal till geologic units and may contain
some volcanic ash in the upper portion of the unit. Depth to water table or restrictive layer is generally about 36
inches,and soils are typically moderately well drained and lack tendency for flooding or ponding. Alderwood soils
cover the entire area of the proposed development. This unit is rated as"somewhat limited"for dwellings without
basements and "slight" erosion hazard by the NRCS(see Appendix).
The lower(southern) parcel soils are mapped as rough broken land,and are typically gravelly sandy loam to
stratified extremely gravelly sandy loam,excessively drained. Below this unit coastal beaches. form the soil unit.
Both of these soil units are rated as"very severe"erosion hazard. The rough broken land sols are rated as"very
limited"for dwellings without basements.
4.0 Geo-hazard Assessment
4.1 Landslide Hazard
Based on the site observations, and literature review, landslide hazard is limited to the bluff slope, below the 300
foot topographic contour as shown in the site vicinity map in the Appendix. The only area of moderately recent
landslides observed on the site is along the beach area where there exist some exposed soil slumps. The slope
breaks(benches)along the bluff appear to be formed by old rotational slumps. These slumps can be seen on LIDAR
(see Figure 5)as scalloped or curvilinear shadowed features along the bluff face oriented southwest-northeast.
Offsets appear to be approximately 20 to 40 feet in the horizontal component and occur in the stratified sediments
below the till layer. Differential permeability rates contribute to the destabilization of these strata and can lead to
development of slip planes along the less permeable,finer layers.
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Figure 5. LIDAR image of subject parcel showing rotational slumping along bluff.(Source: Jefferson County GIS)
4.2 Erosion Hazard
Erosion hazard is limited to the lowermost, southern portion of the site,where the soils are loose, non-cohesive
and excessively drained, prone to water and wind action. Typically this hazard extends from the shoreline, includes
the beach sediments,to the break in slope at about 150 feet above mean sea level,approximately 400 feet
northward from the shoreline (see Appendix).
5.0 Recommendations
5.1 Site Development Recommendations
• For geologic hazard mitigation,a standard buffer distance of 30 feet, measured from top of slope(per
18.22.170(6)(a)Jefferson County Code) is recommended at this site. Buffer is to be permanently marked with a
physical separation marker such as logs or large timber placed end to end,or fencing or other approved
prominent marker. Temporary signage with the following statement`landslide Hazard Area and Buffer—Do
Not Remove or Alter Existing Natural Vegetation" is to be displayed during construction. Buffer area must be
retained in native vegetative state in perpetuity.
• For safety of the proposed structures,a minimum prudent building setback of 100 feet from top of slope is
recommended for all building structures. Setback recommendation is equivalent to a vertical height of bluff as
measured at the maximum distance to uppermost bench level along bluff,and consistent with standard
practice and county requirements. Additional setback is recommended if feasible, in recognition of potential
loss of value to the developed property where shoreline landslides have encroached on development in other
regional shoreline areas.
• To prevent increased discharge of stormwater to the bluff or to adjacent properties,surface runoff from hard
surfaces should be routed away from such areas via careful grading practices to swales or low areas,away from
the bluff,and use of low impact measures such as permeable pavement, pavement and bioswales(where
appropriate), rain garden or other bio-retention area and use of splash blocks with quarry spall for dispersion
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• or in conjunction with contoured slopes directing sheet flow away from the bluff to bioswales, rain garden or
other infiltration measure located upslope of bluff is recommended.
• Avoid underground lawn irrigation systems and unnecessary below-ground water pipes that may break and
lead to the uncontrolled flow of water to the soil and bluff. Keep irrigation to a minimum in all areas of the site,
and avoid discharge of storm water to the bluff slope.
For further information please review the publication published by the Washington State Department of Ecology
(DOE)entitled: "Slope Stabilization and Erosion Control Using Vegetation". This publication can also be viewed on
the DOE website at http://www.ecy.wa.gov/biblio/sea.html under the 1993 and 1994 year heading.The DOE
website also contains additional useful information regarding slope stability and site development, and this
reference is highly recommended.
5.2 Erosion Control Measures During Construction
• Clearing limits should be clearly marked during construction, along with demarcation of landslide buffer zone.
• Best management practices(BMP's)as delineated in the 2005 Stormwater Management Manual for Western
Washington-Volume II shall be installed throughout this project to prevent silt and sediment from entering
downstream waters or discharging to neighboring parcels.
• BMP's shall also be installed to prevent tracking of sediment materials on to public roadways.
• The following site specific BMP's are recommended. A more detailed description of the BMP's listed below
can be found in the Appendix II of this document. These BMP's are intended to be utilized as needed.
1. BMP C101: Preserving Natural Vegetation
2. BMP C102: Buffer Zones
3. BMP C123: Plastic Covering
4. BMP C150: Materials On Hand
5. BMP C151: Concrete Handling
6. BMP C153: Material Delivery,Storage and Containment
7. BMP C180: Small Project Construction Stormwater Pollution Prevention
8. BMP C233: Silt Fence
9. BMP C235: Straw Wattles
• All construction will adhere to existing Jefferson County Codes.Contractor shall coordinate with engineer to
implement an adequate drainage and erosion control plan during the length of this project.
6.0 Limitations and Exclusions
This study and the contents of this report have been completed for use by Mr.Quinten Shay in obtaining necessary
permits and for guidance in prudent development of the subject parcel.This investigation was limited to surface
investigation and observations of the site and relevant literature review. The limited study was done without the
benefit of deep borings,thorough subsurface or regional study or careful measurements taken over time.
Setback recommendations of this report are based upon the fundamental assumption that the future of this slope
will resemble its past as discerned from the geomorphology and the erosional mechanism(s)of the slopes.The
recommended setback may prove insufficient in the very large, but infrequent,earthquakes that have been
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suggested by B.Atwater and others. Users of this report are encouraged to provide as much setback as possible for
improved peace of mind and safety.
The conclusions and recommendations of this report are not transferable to the adjoining or nearby properties.
This report,the field work and the recommendations herein were conscientiously completed in accordance with
the principles of geological and geotechnical science and in conformance with the professional practice of
engineering. NTl provides no other warranty, neither express nor written, herewith. Users who require a level of
reliance beyond the observations and recommendations of this limited study are encouraged to obtain more
detailed geotechnical and geologic studies.
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APPENDIX I
Site Map
Soil Report — Dwellings Without Basements
Soil Report — Erosion Hazard
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Recommended 100'
Setback from Top of Slope
Proposed septic
Required 30'
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ex.break .................................... fg 0'10 shoreline
located @X:••'•
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SCALE IN FEET
SM. REVISION GATE BY CHECKED 0 NORTMKSIERN 7ERRIORIEA INC.2012
DESIGNED,-. 60' I DATE: o4�.0"2 SITE PLAN W/ GEOHAZARD BUFFER & SETBACK
ots6cNEO BT, S N.Q M C. 4^- NORTHWESTERN TERRITORIES, INC.
DRAWN BY: S. M.&M c PARCEL 721 194012 — NEW DEVELOPMENT
CHECKED: CIL EIl9:,een-Lend Stovers-Geologies
RENEW. EMIR. .CONST. FOR: OUINTEN SHAY �1l c«,suaclibn 10tpeclioR-Moieties resting
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Dwellings Without Basements—Jefferson County Area,Washington
(Shay Property_179 Groves Way,Port Ludlow)
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Map Scale:13,130 if prrt�ted on A s¢e(8.5"x 11")sheet.
° Meters o
30 60 120 180
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0 100 200 400 600
USDA Natural Resources Web Soil Survey 3/30/2012
Conservation Service National Cooperative Soil Survey Page 1 of 5
t 7
Dwellings Without Basements—Jefferson County Area,Washington
(Shay Property_179 Groves Way,Port Ludlow)
MAP LEGEND MAP INFORMATION
Area of Interest(AOI) Map Scale:1:3,140 if printed on A size(8.5"rr 11")sheet.
U Area of Interest(AOI) The soil surveys that comprise your AOI were mapped at 1:20,000.
soils
Soil Map Units Warning:Soil Map may not be valid at this scale.
Soil Ratings Enlargement of maps beyond the scale of mapping can cause
Very limited misunderstanding of the detail of mapping and accuracy of soil line
placement.The maps do not show the small areas of contrasting
Q Somewhat limited soils that could have been shown at a more detailed scale.
EI Not limited Please rely on the bar scale on each map sheet for accurate map
Not rated or not available measurements.
Political Features Source of Map: Natural Resources Conservation Service
0 Cities Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov
Coordinate System: UTM Zone 10N NAD83
Water Features
Streams and Canals This product is generated from the USDA-NRCS certified data as of
the version date(s)listed below.
Transportation
±++ Rails
Soil Survey Area: Jefferson County Area,Washington
Survey Area Data: Version 7,Sep 22,2009
rV Interstate Highways
Date(s)aerial images were photographed: 7/21/2006
US Routes
The orthophoto or other base map on which the soil lines were
Major Roads compiled and digitized probably differs from the background
Local Roads imagery displayed on these maps.As a result,some minor shifting
of map unit boundaries may be evident
USDA Natural Resources Web Soil Survey 3/30/2012
Conservation Service National Cooperative Soil Survey Page 2 of 5
Dwellings Without Basements—Jefferson County Area,Washington Shay Property_179 Groves Way,Port Ludlow
Dwellings Without Basements
Dwellings Without Basements—Summary by Map Unit—Jefferson County Area,Washington(WA631)
Map unit Map unit name Rating Component name Rating reasons Acres in Percent of A01;
symbol (percent) (numeric values) AOi
AIC Alderwood gravelly Somewhat limited Alderwood(100%) Depth to saturated 14.7 59.7%
sandy loam,0 to zone(0.10)
15 percent slopes
Slope(0.00)
Co Coastal beaches Not rated Beaches(100%) 2.1 8.6%
Ro Rough broken land Very limited Rough broken land Too steep(1.00) 6.4 25.8%
(100%)
Subtotals for Soil Survey Area 23.2 94.1%
Totals for Area of Interest 24.6 100.0%
Dwellings Without Basements—Summary by Rating Value
Rating Acres in A01 - Percent of AOI
Somewhat limited 14.7 59.7%
Very limited 6.4 25.8%
Null or Not Rated 2.1 8.6%
Totals for Area of Interest 24.6 100.0%
USDA Natural Resources Web Soil Survey 313W2012
Conservation Service National Cooperative Soil Survey Page 3 of 5
Dwellings Without Basements—Jefferson County Area,Washington Shay Property_179 Groves Way,Port Ludlow
it
Description
Dwellings are single-family houses of three stories or less. For dwellings without
basements, the foundation is assumed to consist of spread footings of reinforced
concrete built on undisturbed soil at a depth of 2 feet or at the depth of maximum
frost penetration,whichever is deeper.
The ratings for dwellings are based on the soil properties that affect the capacity of
the soil to support a load without movement and on the properties that affect
excavation and construction costs. The properties that affect the load-supporting
capacity include depth to a water table, ponding, flooding, subsidence, linear
extensibility(shrink-swell potential),and compressibility.Compressibility is inferred
from the Unified classification of the soil. The properties that affect the ease and
amount of excavation include depth to a water table,ponding,flooding,slope,depth
to bedrock or a cemented pan, hardness of bedrock or a cemented pan, and the
amount and size of rock fragments.
The ratings are both verbal and numerical. Rating class terms indicate the extent
to which the soils are limited by all of the soil features that affect the specified use.
"Not limited"indicates that the soil has features that are very favorable for the
specified use. Good performance and very low maintenance can be expected.
"Somewhat limited" indicates that the soil has features that are moderately
favorable for the specified use. The limitations can be overcome or minimized by
special planning, design, or installation. Fair performance and moderate
maintenance can be expected."Very limited"indicates that the soil has one or more
features that are unfavorable for the specified use.The limitations generally cannot
be overcome without major soil reclamation, special design, or expensive
installation procedures.Poor performance and high maintenance can be expected.
Numerical ratings indicate the severity of individual limitations. The ratings are
shown as decimal fractions ranging from 0.01 to 1.00. They indicate gradations
between the point at which a soil feature has the greatest negative impact on the
use(1.00)and the point at which the soil feature is not a limitation (0.00).
The map unit components listed for each map unit in the accompanying Summary
by Map Unit table in Web Soil Survey or the Aggregation Report in Soil Data Viewer
are determined by the aggregation method chosen.An aggregated rating class is
shown for each map unit.The components listed for each map unit are only those
that have the same rating class as listed for the map unit.The percent composition
of each component in a particular map unit is presented to help the user better
understand the percentage of each map unit that has the rating presented.
Other components with different ratings may be present in each map unit.The
ratings for all components, regardless of the map unit aggregated rating, can be
viewed by generating the equivalent report from the Soil Reports tab in Web Soil
Survey or from the Soil Data Mart site. Onsite investigation may be needed to
validate these interpretations and to confirm the identity of the soil on a given site.
Rating Options
Aggregation Method: Dominant Condition
USDA Natural Resources Web Soil Survey 3/30/2012
Conservation Service National Cooperative Soil Survey Page 4 of 5
Dwellings Without Basements-Jefferson County Area,Washington Shay Property_179 Groves Way,Port Ludlow
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
USDA Natural Resources Web Soil Survey 3/30/2012
Conservation Service National Cooperative Soil Survey Page 5 of 5
Erosion Hazard(Off-Road,Off-Trail)--Jefferson County Area,Washington
(Shay Property_179 Groves Way,Port Ludlow)
O V N N O N N N 520640
520720 520800 520880 520960 521040
47°49'3" --
fit
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47°48'41" ... - .. 47°48'41"
520640 520720 520800 520880 520960 521040
N _
Map Scale:1:3,200 if prated on A size(8.5"x 11")sheet. "'
0
v Meters v
0 30 60 120 180 r
IANFeet
/V 0 100 200 400 600
USDA Natural Resources Web Soil Survey 3/30/2012
Conservation Service National Cooperative Soil Survey Page 1 of 4
Erosion Hazard(Off-Road,Off-Trail)—Jefferson County Area,Washington
(Shay Property_179 Groves Way,Port Ludlow)
MAP LEGEND MAP INFORMATION
Area of Interest(AOl) Map Scale:1:3,200 if printed on A size(8.5"■11")sheet
I_E_ Area of Interest(AOl) The soil surveys that comprise your AOl were mapped at 1:20,000.
Soils
_JI soil Map Units Warning:Soil Map may not be valid at this scale.
Soil Ratings Enlargement of maps beyond the scale of mapping can cause
very severe misunderstanding of the detail of mapping and accuracy of soil line
placement The maps do not show the small areas of contrasting
Severe soils that could have been shown at a more detailed scale.
Ei Moderate
Please rely on the bar scale on each map sheet for accurate map
Slight measurements.
Not rated or not available Source of Map: Natural Resources Conservation Service
Political Features Web Soil Survey URL: http://websoilsurvey.nres.usda.gov
Coordinate System: UTM Zone 10N NAD83
® Cities
This product is generated from the USDA-NRCS certified data as of
Water Features the version date(s)listed below.
,..,- Streams and Canals
Soil Survey Area: Jefferson County Area,Washington
Transportation Survey Area Data: Version 7,Sep 22,2009
Rats
Date(s)aerial images were photographed: 7/21/2006
ov Interstate Highways
The orthophoto or other base map on which the soil lines were
Us Routes compiled and digitized probably differs from the background
Major Roads imagery displayed on these maps.As a result,some minor shifting
of map unit boundaries may be evident
N Local Roads
Natural Resources Web Soil Survey 3/30/2012
Conservation Service National Cooperative Soil Survey Page 2 of 4
•
Erosion Hazard(Off-Road,Off-Trail)–Jefferson County Area,Washington Shay Property_179 Groves Way,Port Ludlow
Erosion Hazard (Off-Road, Off-Trail)
Erosion Hazard(Off-Road,Off-Trail)—Summary by Map Unit-:Jefferson County (WA631)
Map unit ..Map unit name Rating Component Rating reasons(numeric values) Acres in ' Percent'of
symbol " " name(percent) -: A01 AOI <-
AIC Alderwood Slight Alderwood(100%) 17.3 58.9%
gravelly sandy
loam,0 to 15
percent slopes
Co Coastal beaches Very Beaches(100%) Not rated(1.00) 2.5 8.4%
Severe
Ro Rough broken Very severe Rough broken Slope/erodibility(0.95) 7.4 25.3%
land land(100%)
Subtotals for Soil Survey Area 27.2 92.5%
Totals for Area of Interest 29.4 100.0%
Erosion.Hazard(Off-Road,Off—Trail)—Summary by Rating Value
Rating Acres in A01 - Percent of AOl
Slight 17.3 58.9%
Very severe 9.9 33.6%
Very Severe 9.9 33.6%
Totals for Area of Interest 29.4 100.0%
USDA Natural Resources Web Soil Survey 3/30/2012
Conservation Service National Cooperative Soil Survey Page 3 of 4
Dwellings Without Basements—Jefferson County Area,Washington Shay Property_179 Groves Way,Port Ludlow
it
Description
Dwellings are single-family houses of three stories or less. For dwellings without
basements, the foundation is assumed to consist of spread footings of reinforced
concrete built on undisturbed soil at a depth of 2 feet or at the depth of maximum
frost penetration,whichever is deeper.
The ratings for dwellings are based on the soil properties that affect the capacity of
the soil to support a load without movement and on the properties that affect
excavation and construction costs. The properties that affect the load-supporting
capacity include depth to a water table, ponding, flooding, subsidence, linear
extensibility(shrink-swell potential),and compressibility.Compressibility is inferred
from the Unified classification of the soil. The properties that affect the ease and
amount of excavation include depth to a water table,ponding,flooding,slope,depth
to bedrock or a cemented pan, hardness of bedrock or a cemented pan, and the
amount and size of rock fragments.
The ratings are both verbal and numerical. Rating class terms indicate the extent
to which the soils are limited by all of the soil features that affect the specified use.
"Not limited"indicates that the soil has features that are very favorable for the
specified use. Good performance and very low maintenance can be expected.
"Somewhat limited" indicates that the soil has features that are moderately
favorable for the specified use. The limitations can be overcome or minimized by
special planning, design, or installation. Fair performance and moderate
maintenance can be expected."Very limited"indicates that the soil has one or more
features that are unfavorable for the specified use.The limitations generally cannot
be overcome without major soil reclamation, special design, or expensive
installation procedures.Poor performance and high maintenance can be expected.
Numerical ratings indicate the severity of individual limitations. The ratings are
shown as decimal fractions ranging from 0.01 to 1.00. They indicate gradations
between the point at which a soil feature has the greatest negative impact on the
use(1.00)and the point at which the soil feature is not a limitation (0.00).
The map unit components listed for each map unit in the accompanying Summary
by Map Unit table in Web Soil Survey or the Aggregation Report in Soil Data Viewer
are determined by the aggregation method chosen.An aggregated rating class is
shown for each map unit.The components listed for each map unit are only those
that have the same rating class as listed for the map unit.The percent composition
of each component in a particular map unit is presented to help the user better
understand the percentage of each map unit that has the rating presented.
Other components with different ratings may be present in each map unit.The
ratings for all components, regardless of the map unit aggregated rating, can be
viewed by generating the equivalent report from the Soil Reports tab in Web Soil
Survey or from the Soil Data Mart site. Onsite investigation may be needed to
validate these interpretations and to confirm the identity of the soil on a given site.
Rating Options
Aggregation Method: Dominant Condition
USDA Natural Resources Web Soil Survey 3/30/2012
Conservation Service National Cooperative Soil Survey Page 4 of 5
Dwellings Without Basements-Jefferson County Area,Washington Shay Property_179 Groves Way,Port Ludlow
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
USDA Natural Resources Web Soil Survey 3/30/2012
Conservation Service National Cooperative Soil Survey Page 5 of 5
Erosion Hazard(Off-Road,Off-Trail)--Jefferson County Area,Washington
(Shay Property_179 Groves Way,Port Ludlow)
O V N N O N N N 520640
520720 520800 520880 520960 521040
47°49'3" --
fit
o°
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N fl N
W
b
$ W N b N � j . k
V ;:• h OV
m m
rd N
b
m
n
O _'. 0
N N
b b
O
m
b 0
b
N
N
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Ol W
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47°48'41" ... - .. 47°48'41"
520640 520720 520800 520880 520960 521040
N _
Map Scale:1:3,200 if prated on A size(8.5"x 11")sheet. "'
0
v Meters v
0 30 60 120 180 r
IANFeet
/V 0 100 200 400 600
USDA Natural Resources Web Soil Survey 3/30/2012
Conservation Service National Cooperative Soil Survey Page 1 of 4
Erosion Hazard(Off-Road,Off-Trail)—Jefferson County Area,Washington
(Shay Property_179 Groves Way,Port Ludlow)
MAP LEGEND MAP INFORMATION
Area of Interest(AOl) Map Scale:1:3,200 if printed on A size(8.5"■11")sheet
I_E_ Area of Interest(AOl) The soil surveys that comprise your AOl were mapped at 1:20,000.
Soils
_JI soil Map Units Warning:Soil Map may not be valid at this scale.
Soil Ratings Enlargement of maps beyond the scale of mapping can cause
very severe misunderstanding of the detail of mapping and accuracy of soil line
placement The maps do not show the small areas of contrasting
Severe soils that could have been shown at a more detailed scale.
Ei Moderate
Please rely on the bar scale on each map sheet for accurate map
Slight measurements.
Not rated or not available Source of Map: Natural Resources Conservation Service
Political Features Web Soil Survey URL: http://websoilsurvey.nres.usda.gov
Coordinate System: UTM Zone 10N NAD83
® Cities
This product is generated from the USDA-NRCS certified data as of
Water Features the version date(s)listed below.
,..,- Streams and Canals
Soil Survey Area: Jefferson County Area,Washington
Transportation Survey Area Data: Version 7,Sep 22,2009
Rats
Date(s)aerial images were photographed: 7/21/2006
ov Interstate Highways
The orthophoto or other base map on which the soil lines were
Us Routes compiled and digitized probably differs from the background
Major Roads imagery displayed on these maps.As a result,some minor shifting
of map unit boundaries may be evident
N Local Roads
Natural Resources Web Soil Survey 3/30/2012
Conservation Service National Cooperative Soil Survey Page 2 of 4
•
Erosion Hazard(Off-Road,Off-Trail)–Jefferson County Area,Washington Shay Property_179 Groves Way,Port Ludlow
Erosion Hazard (Off-Road, Off-Trail)
Erosion Hazard(Off-Road,Off-Trail)—Summary by Map Unit-:Jefferson County (WA631)
Map unit ..Map unit name Rating Component Rating reasons(numeric values) Acres in ' Percent'of
symbol " " name(percent) -: A01 AOI <-
AIC Alderwood Slight Alderwood(100%) 17.3 58.9%
gravelly sandy
loam,0 to 15
percent slopes
Co Coastal beaches Very Beaches(100%) Not rated(1.00) 2.5 8.4%
Severe
Ro Rough broken Very severe Rough broken Slope/erodibility(0.95) 7.4 25.3%
land land(100%)
Subtotals for Soil Survey Area 27.2 92.5%
Totals for Area of Interest 29.4 100.0%
Erosion.Hazard(Off-Road,Off—Trail)—Summary by Rating Value
Rating Acres in A01 - Percent of AOl
Slight 17.3 58.9%
Very severe 9.9 33.6%
Very Severe 9.9 33.6%
Totals for Area of Interest 29.4 100.0%
USDA Natural Resources Web Soil Survey 3/30/2012
Conservation Service National Cooperative Soil Survey Page 3 of 4
•
Erosion Hazard(Off-Road,Off-Trail)—Jefferson County Area,Washington Shay Property_179 Groves Way,Port Ludlow
Description
The ratings in this interpretation indicate the hazard of soil loss from off-road and
off-trail areas after disturbance activities that expose the soil surface. The ratings
9
are based on slope and soil erosion factor K.The soil loss is caused by sheet or rill
erosion in off-road or off-trail areas where 50 to 75 percent of the surface p has been
exposed by logging, grazing, mining, or other kinds of disturbance.
The ratings are both verbal i
g erbal and numerical. The hazard is described as"slight,"
9
"moderate,""severe,"or"very severe."A rating of"slight" indicates that erosion is
unlikely under ordinary climatic conditions;"moderate"indicates that some erosion
is likely and that erosion-control measures may be needed; "severe"indicates that
erosion is very likely and that erosion-control measures, including revegetation of
bare areas, are advised; and"very severe"indicates that significant erosion is
expected,loss of soil productivity and off-site damage are likely,and erosion-control
measures are costly and generally impractical.
Numerical ratings indicate the severity of individual limitations. The ratings are
shown as decimal fractions ranging from 0.01 to 1.00. They indicate gradations
between the point at which a soil feature has the greatest negative impact on the
specified aspect of forestland management(1.00)and the point at which the soil
feature is not a limitation (0.00).
The map unit components listed for each map unit in the accompanying Summary
by Map Unit table in Web Soil Survey or the Aggregation Report in Soil Data Viewer
are determined by the aggregation method chosen.An aggregated rating class is
shown for each map unit. The components listed for each map unit are only those
that have the same rating class as listed for the map.unit.The percent composition
of each component in a particular map unit is presented to help the user better
understand the percentage of each map unit that has the rating presented.
9 P gp
Other components with different ratings may be present in each map unit. The
ratings for all components, regardless of the map unit aggregated rating, can be
viewed by generating the equivalent report from the Soil Reports tab in Web Soil
Survey or from the Soil Data Mart site. Onsite investigation may be needed to
validate these interpretations and to confirm the identity of the soil on a given site.
Rating Options
Aggregation Method: Dominant Condition
. Component Percent Cutoff. None Specified
Tie-break Rule: Higher
LSDA
Natural Resources Web Soil Survey 3/30/2012
Conservation Service National Cooperative Soil Survey Page 4 of 4
APPENDIX II
Selected BMP's
10
4.1 Source Control BMPs
BMP C101: Preserving Natural Vegetation
Purpose The purpose of preserving natural vegetation is to reduce erosion wherever
practicable. Limiting site disturbance is the single most effective method
for reducing erosion. For example, conifers can hold up to about 50
percent of all rain that falls during a storm. Up to 20-30 percent of this rain
may never reach the ground but is taken up by the tree or evaporates.
Another benefit is that the rain held in the tree can be released slowly to the
ground after the storm.
Conditions of Use • Natural vegetation should be preserved on steep slopes,near
perennial and intermittent watercourses or swales, and on building
sites in wooded areas.
• As required by local governments.
Design and Natural vegetation can be preserved in natural clumps or as individual
Installation trees, shrubs and vines.
Specifications
The preservation of individual plants is more difficult because heavy
equipment is generally used to remove unwanted vegetation. The points
to remember when attempting to save individual plants are:
• Is the plant worth saving? Consider the location, species,size,age,
vigor,and the work involved. Local governments may also have
ordinances to save natural vegetation and trees.
• Fence or clearly mark areas around trees that are to be saved. It is
preferable to keep ground disturbance away from the trees at least as
far out as the dripline.
Plants need protection from three kinds of injuries:
• Construction Equipment-This injury can be above or below the
ground level. Damage results from scarring,cutting of roots, and
compaction of the soil. Placing a fenced buffer zone around plants to
be saved prior to construction can prevent construction equipment
injuries.
• Grade Changes-Changing the natural ground level will alter grades,
which affects the plant's ability to obtain the necessary air,water,and
minerals. Minor fills usually do not cause problems although
sensitivity between species does vary and should be checked. Trees
can tolerate fill of 6 inches or less. For shrubs and other plants,the fill
should be less.
When there are major changes in grade, it may become necessary to
supply air to the roots of plants. This can be done by placing a layer of
gravel and a tile system over the roots before the fill is made. A tile
4-2 Volume 1l-Construction Stormwater Pollution Prevention February 2005
system protects a tree from a raised grade. The tile system should be
laid out on the original grade leading from a dry well around the tree
trunk. The system should then be covered with small stones to allow
air to circulate over the root area.
Lowering the natural ground level can seriously damage trees and
shrubs.The highest percentage of the plant roots are in the upper 12
inches of the soil and cuts of only 2-3 inches can cause serious injury.
To protect the roots it may be necessary to terrace the immediate area
around the plants to be saved. If roots are exposed, construction of
retaining walls may be needed to keep the soil in place. Plants can
also be preserved by leaving them on an undisturbed,gently sloping
mound. To increase the chances for survival, it is best to limit grade
changes and other soil disturbances to areas outside the dripline of the
plant.
• Excavations-Protect trees and other plants when excavating for
drainfields,power,water,and sewer lines. Where possible, the
trenches should be routed around trees and large shrubs. When this is
not possible, it is best to tunnel under them. This can be done with
hand tools or with power augers. If it is not possible to route the
trench around plants to be saved,then the following should be
observed:
Cut as few roots as possible. When you have to cut, cut clean. Paint
cut root ends with a wood dressing like asphalt base paint.
Backfill the trench as soon as possible.
Tunnel beneath root systems as close to the center of the main trunk to
preserve most of the important feeder roots.
Some problems that can be encountered with a few specific trees are:
• Maple, Dogwood, Red alder, Western hemlock, Western red cedar,
and Douglas fir do not readily adjust to changes in environment and
special care should be taken to protect these trees.
• The windthrow hazard of Pacific silver fir and madronna is high, while
that of Western hemlock is moderate. The danger of windthrow
increases where dense stands have been thinned. Other species(unless
they are on shallow, wet soils less than 20 inches deep)have a low
windthrow hazard.
• Cottonwoods, maples,and willows have water-seeking roots. These
can cause trouble in sewer lines and infiltration fields. On the other
hand,they thrive in high moisture conditions that other trees would
not.
• Thinning operations in pure or mixed stands of Grand fir, Pacific silver
fir, Noble fir, Sitka spruce, Western red cedar, Western hemlock,
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Pacific dogwood, and Red alder can cause serious disease problems.
Disease can become established through damaged limbs,trunks, roots,
and freshly cut stumps. Diseased and weakened trees are also
susceptible to insect attack.
Maintenance • Inspect flagged and/or fenced areas regularly to make sure flagging or
Standards fencing has not been removed or damaged. If the flagging or fencing
has been damaged or visibility reduced, it shall be repaired or
replaced immediately and visibility restored.
• If tree roots have been exposed or injured, "prune" cleanly with an
appropriate pruning saw or lopers directly above the damaged roots
and recover with native soils. Treatment of sap flowing trees (fir,
hemlock, pine, soft maples) is not advised as sap forms a natural
healing barrier.
4-4 Volume II—Construction Stormwater Pollution Prevention February 2005
t 1
BMP C102: Buffer Zones
Purpose An undisturbed area or strip of natural vegetation or an established
suitable planting that will provide a living filter to reduce soil erosion and
runoff velocities.
Conditions of Use Natural buffer zones are used along streams, wetlands and other bodies of
water that need protection from erosion and sedimentation. Vegetative
buffer zones can be used to protect natural swales and can be incorporated
into the natural landscaping of an area.
Critical-areas buffer zones should not be used as sediment treatment areas.
These areas shall remain completely undisturbed. The local permitting
authority may expand the buffer widths temporarily to allow the use of the
expanded area for removal of sediment.
Design and • Preserving natural vegetation or plantings in clumps, blocks, or strips
Installation is generally the easiest and most successful method.
Specifications Leave all unstable steep slopes in natural vegetation.
•• Mark clearing limits and keep all equipment and construction debris
out of the natural areas. Steel construction fencing is the most
effective method in protecting sensitive areas and buffers.
Alternatively,wire-backed silt fence on steel posts is marginally
effective. Flagging alone is typically not effective.
• Keep all excavations outside the dripline of trees and shrubs.
• Do not push debris or extra soil into the buffer zone area because it
will cause damage from burying and smothering.
• Vegetative buffer zones for streams, lakes or other waterways shall be
established by the local permitting authority or other state or federal
permits or approvals.
Maintenance • Inspect the area frequently to make sure flagging remains in place
Standards and the area remains undisturbed.
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BMP C123: Plastic Covering
Purpose Plastic covering provides immediate, short-term erosion protection to
slopes and disturbed areas.
Conditions of • Plastic covering may be used on disturbed areas that require cover
Use measures for less than 30 days, except as stated below.
• Plastic is particularly useful for protecting cut and fill slopes and
stockpiles. Note: The relatively rapid breakdown of most polyethylene
sheeting makes it unsuitable for long-term (greater than six months)
applications.
• Clear plastic sheeting can be used over newly-seeded areas to create a
greenhouse effect and encourage grass growth if the hydroseed was
installed too late in the season to establish 75 percent grass cover, or if
the wet season started earlier than normal. Clear plastic should not be
used for this purpose during the summer months because the resulting
high temperatures can kill the grass.
• Due to rapid runoff caused by plastic sheeting,this method shall not be
used upslope of areas that might be adversely impacted by
concentrated runoff. Such areas include steep and/or unstable slopes.
• While plastic is inexpensive to purchase,the added cost of installation,
maintenance, removal, and disposal make this an expensive material,
up to$1.50-2.00 per square yard.
• Whenever plastic is used to protect slopes, water collection measures
must be installed at the base of the slope. These measures include
plastic-covered berms, channels, and pipes used to covey clean
rainwater away from bare soil and disturbed areas. At no time is clean
runoff from a plastic covered slope to be mixed with dirty runoff from
a project.
• Other uses for plastic include:
1. Temporary ditch liner;
2. Pond liner in temporary sediment pond;
3. Liner for bermed temporary fuel storage area if plastic is not
reactive to the type of fuel being stored;
4. Emergency slope protection during heavy rains;and,
5. Temporary drainpipe("elephant trunk")used to direct water.
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5
Design and • Plastic slope cover must be installed as follows:
Installation I Run plastic up and down slope, not across slope;
Specifications
2. Plastic may be installed perpendicular to a slope if the slope length
is less than 10 feet;
3. Minimum of 8-inch overlap at seams;
4. On long or wide slopes, or slopes subject to wind,all seams should
be taped;
5. Place plastic into a small (12-inch wide by 6-inch deep) slot trench
at the top of the slope and backfill with soil to keep water from
flowing underneath;
6. Place sand filled burlap or geotextile bags every 3 to 6 feet along
seams and pound a wooden stake through each to hold them in
place;
7. Inspect plastic for rips, tears, and open seams regularly and repair
immediately. This prevents high velocity runoff from contacting
bare soil which causes extreme erosion;
8. Sandbags may be lowered into place tied to ropes. However, all
sandbags must be staked in place.
• Plastic sheeting shall have a minimum thickness of 0.06 millimeters.
• If erosion at the toe of a slope is likely,a gravel berm, riprap, or other
suitable protection shall be installed at the toe of the slope in order to
reduce the velocity of runoff.
Maintenance • Torn sheets must be replaced and open seams repaired.
Standards
• If the plastic begins to deteriorate due to ultraviolet radiation, it must
be completely removed and replaced.
• When the plastic is no longer needed, it shall be completely removed.
• Dispose of old tires appropriately.
February 2005 Volume II-Construction Stormwater Pollution Prevention 4-27
Y 1
BMP C151: Concrete Handling
Purpose Concrete work can generate process water and slurry that contain fine
particles and high pH,both of which can violate water quality standards in
the receiving water. This BMP is intended to minimize and eliminate
concrete process water and slurry from entering waters of the state.
Conditions of Use Any time concrete is used, these management practices shall be utilized.
Concrete construction projects include,but are not limited to,the
following:
• Curbs
• Sidewalks
• Roads
• Bridges
• Foundations
• Floors
• Runways
Design and • Concrete truck chutes, pumps, and internals shall be washed out only
Installation into formed areas awaiting installation of concrete or asphalt.
Specifications
• Unused concrete remaining in the truck and pump shall be returned to
the originating batch plant for recycling.
• Hand tools including, but not limited to, screeds, shovels, rakes, floats,
and trowels shall be washed off only into formed areas awaiting
installation of concrete or asphalt.
• Equipment that cannot be easily moved, such as concrete pavers, shall
only be washed in areas that do not directly drain to natural or
constructed stormwater conveyances.
• Washdown from areas such as concrete aggregate driveways shall not
drain directly to natural or constructed stormwater conveyances.
• When no formed areas are available,washwater and leftover product
shall be contained in a lined container. Contained concrete shall be
disposed of in a manner that does not violate groundwater or surface
water quality standards.
Maintenance Containers shall be checked for holes in the liner daily during concrete
Standards pours and repaired the same day.
February 2005 Volume I!-Construction Stormwater Pollution Prevention 4-43
k ,
BMP C153: Material Delivery, Storage and Containment
Purpose Prevent,reduce, or eliminate the discharge of pollutants from
material delivery and storage to the stormwater system or
watercourses by minimizing the storage of hazardous materials
onsite, storing materials in a designated area, and installing
secondary containment.
Conditions of Use These procedures are suitable for use at all construction sites with
delivery and storage of the following materials:
• Petroleum products such as fuel, oil and grease
• Soil stabilizers and binders(e.g. Polyacrylamide)
• Fertilizers, pesticides and herbicides
• Detergents
• Asphalt and concrete compounds
• Hazardous chemicals such as acids, lime, adhesives,paints,solvents
and curing compounds
• Any other material that may be detrimental if released to the
environment
Design and The following steps should be taken to minimize risk:
Installation Temporary storage area should be located away from vehicular traffic,
•Specifications near the construction entrance(s), and away from waterways or storm
drains.
• Material Safety Data Sheets(MSDS) should be supplied for all
materials stored. Chemicals should be kept in their original labeled
containers.
• Hazardous material storage on-site should be minimized.
• Hazardous materials should be handled as infrequently as possible.
• During the wet weather season (Oct 1 —April 30), consider storing
materials in a covered area.
• Materials should be stored in secondary containments, such as earthen
dike, horse trough, or even a children's wading pool for non-reactive
materials such as detergents, oil, grease, and paints. Small amounts of
material may be secondarily contained in "bus boy"trays or concrete
mixing trays.
• Do not store chemicals, drums, or bagged materials directly on the
ground. Place these items on a pallet and, when possible, in secondary
containment.
February 2005 Volume II—Construction Storm water Pollution Prevention 4-45
• If drums must be kept uncovered, store them at a slight angle to reduce
ponding of rainwater on the lids to reduce corrosion.Domed plastic
covers are inexpensive and snap to the top of drums, preventing water
from collecting.
Material Storage Areas and Secondary Containment Practices:
• Liquids, petroleum products, and substances listed in 40 CFR Parts
110, 117,or 302 shall be stored in approved containers and drums and
shall not be overfilled.Containers and drums shall be stored in
temporary secondary containment facilities.
• Temporary secondary containment facilities shall provide for a spill
containment volume able to contain precipitation from a 25 year, 24
hour storm event, plus 10%of the total enclosed container volume of
all containers, or 110%of the capacity of the largest container within
its boundary, whichever is greater.
• Secondary containment facilities shall be impervious to the materials
stored therein for a minimum contact time of 72 hours.
• Secondary containment facilities shall be maintained free of
accumulated rainwater and spills. In the event of spills or leaks,
accumulated rainwater and spills shall be collected and placed into
drums. These liquids shall be handled as hazardous waste unless
testing determines them to be non-hazardous.
• Sufficient separation should be provided between stored containers to
allow for spill cleanup and emergency response access.
• During the wet weather season (Oct 1 —April 30), each secondary
containment facility shall be covered during non-working days, prior
to and during rain events.
• Keep material storage areas clean,organized and equipped with an
ample supply of appropriate spill clean-up material (spill kit).
• The spill kit should include, at a minimum:
• 1-Water Resistant Nylon Bag
• 3-Oil Absorbent Socks 3"x 4'
• 2-Oil Absorbent Socks 3"x 10'
• 12-Oil Absorbent Pads 17"x19"
• 1-Pair Splash Resistant Goggles
• 3-Pair Nitrile Gloves
• 10-Disposable Bags with Ties
• Instructions
4-46 Volume ll—Construction Stormwater Pollution Prevention February 2005
E +
BMP C180: Small Project Construction Stormwater Pollution Prevention
Purpose To prevent the discharge of sediment and other pollutants to the maximum
extent practicable from small construction projects.
Conditions of Use On small construction projects, those adding or replacing less than 2,000
square feet of impervious surface or clearing less than 7,000 square feet.
Design and • Plan and implement proper clearing and grading of the site. It is most
Installation important only to clear the areas needed, thus keeping exposed areas
Specifications to a minimum. Phase clearing so that only those areas that are actively
being worked are uncovered.
Note: Clearing limits should be flagged in the lot or area prior to
initiating clearing.
• Soil shall be managed in a manner that does not permanently compact
or deteriorate the final soil and landscape system. If disturbance and/or
compaction occur the impact must be corrected at the end of the
construction activity. This shall include restoration of soil depth, soil
quality, permeability, and percent organic matter. Construction
practices must not cause damage to or compromise the design of
permanent landscape or infiltration areas.
• Locate excavated basement soil a reasonable distance behind the curb,
such as in the backyard or side yard area. This will increase the
distance eroded soil must travel to reach the storm sewer system. Soil
piles should be covered until the soil is either used or removed. Piles
should be situated so that sediment does not run into the street or
adjoining yards.
• Backfill basement walls as soon as possible and rough grade the lot.
This will eliminate large soil mounds, which are highly erodible, and
prepares the lot for temporary cover,which will further reduce erosion
potential.
• Remove excess soil from the site as soon as possible after backfilling.
This will eliminate any sediment loss from surplus fill.
• If a lot has a soil bank higher than the curb,a trench or berm should be
installed moving the bank several feet behind the curb. This will
reduce the occurrence of gully and rill erosion while providing a
storage and settling area for stormwater.
• The construction entrance should be stabilized where traffic will be
leaving the construction site and traveling on paved roads or other
paved areas within 1,000 feet of the site.
February 2005 Volume II—Construction Stormwater Pollution Prevention 4-55
•
• Provide for periodic street cleaning to remove any sediment that may
have been tracked out. Sediment should be removed by shoveling or
sweeping and carefully removed to a suitable disposal area where it
will not be re-eroded.
• Utility trenches that run up and down slopes must be backfilled within
seven days. Cross-slope trenches may remain open throughout
construction to provide runoff interception and sediment trapping,
provided that they do not convey turbid runoff off site.
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