updated drainage report.pdfBEYLER
CONSULTING
Issaquah Office
455 Rainier Blvd N
Issaquah, WA 98027
(425) 392-8055
w
FOR
Lakewood Office
7602 Bridgeport Way W Ste 3D
Lakewood, WA 98499
(253) 301-4157
(SMALL SITE, CATEGORY 2 PROJECT)
721 Edmonds Way
Edmonds, WA 98020
Applicant:
Thomas Chung
721 Edmonds Way
Edmonds, WA 98020
Prepared by:
Brandon Loucks, P.E.
Beyler Consulting
7602 Bridgeport Way SW, Suite 3D
Lakewood, WA 98499
253-301-4157
Job No. 16-089
December 28, 2016
Plan. Design. Manage
CIVIL 8& STRUCTURAL ENGINEERING i LAND SURVEYING i LAND PLANNING
PROJECT MANAGEMENT I PERMIT EXPEDITING I FEASIBILITY
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Category 2 Small Site Drainage Report Chung Short Plat
December 2016
1. Project Description: The proposed project is a three -lot short subdivision, per ECDC
20.75, on an existing 0.46 -acre parcel (#00745300000500). It is classified as a small
site, category 2 project and is subject to RS -6 zoning requirements. See the Project
Classification chart and the end of this report, Handout E72.
The proposed project is subject to the 2005 Stormwater Management Manual for Western
Washington (Ecology 2005) and Exhibit A, the 2010 Stormwater Code Supplement to
Edmonds Community Development Code Chapter 18.30 (Edmonds 2010).
2. Existing Site Conditions: The subject site is a SW -facing, 20,155 sf lot located
approximately one mile inland from Puget Sound in the Edmonds Way Direct Discharge
Basin. It was created as lot 5 of the Pinestone Plat per Snohomish County records. There
are two access points to the site via driveway drops on Edmonds Way (SR -104). There is
a single home on the site along with a gravel driveway, a concrete loop driveway,
concrete patio and walkway, rockeries, and landscaping consisting of lawn, shrubs, and
trees. The existing impervious area on the site is 9,598 sf, or 48% of the parcel area.
The site generally slopes from NE to SW at an average slope of 4%, with a total relief of
8 ft. The steepest portion of the site is a 35' stretch of gravel driveway that slopes toward
the road at 8%. Site soils consist primarily of Everett very gravelly sandy loam, which is
in hydrologic soils group A and highly conducive to infiltration. Runoff from the site that
does not infiltrate drains as sheet flow or shallow, subsurface flow to an existing 48"
storm drain in Edmonds Way. Site soils are described in an NRCS Custom Soil Resource
Report attached at the end of this drainage report.
3. Developed Site Conditions: The proposed/assumed new plus replaced impervious
surface is 9,422 sf. Of the proposed impervious area, 1,922 sf is a 12' wide shared access
driveway, within a 15' wide easement, serving lots 1 and 3. This is under the 5,000 sf
threshold for runoff treatment for pollution -generating impervious surface (PGIS). The
remaining 7,500 sf of impervious surface will be composed of roofs and other hard
surfaces spread over the three lots, which assumes 2,000 sf for each rooftop and 500 sf
for each driveway.
Runoff from the proposed shard access road will be collected by a series of catch basins
and tightlined to the existing 48" storm main within SR -104 (Edmonds Way). Stormwater
for the three lots will be managed by onsite/LID techniques and dispersion/infiltration as
described in Chapter 5 of the City of Edmonds Stormwater Supplement. Further detail
of onsite stormwater management will be provided at the time of building permit
application when the exact footprints and driveway locations are known.
Plana Design.'Mairii.age
CIVIL &'�TRI.CILPC?.AL ENGMEERING, f LANDL!G2,VIi.-b'Sd , ( P.LAN(ID PLAIN(WlC`<VC
PIi�tOJE.i6,::T E�II�!ur�P«GIi..IMEP u �I PgC',fC_(� T EXPEDITING � V11iii1 SIBIIJL.flN
Category 2 Small Site Drainage Report Chung Short Plat
December 2016
4. Small Site Minimum Requirements (SSMRs)
Per City of Edmonds Stormwater Supplement Chapter 5.
SSMR #1 — Preparation of Stormwater Site Plan
This report combined with the Site Development Plans addresses this requirement.
SSMR #2 — Construction Stormwater Pollution Prevention Plan
The Site Development Plans include information and methods addressing this
requirement.
SSMR #3 — Source Control of Pollution
Specific source controls are not required for single family residential sites.
SSMR #4 — Preservation of Natural Drainage Systems and Outfalls
The proposed development preserves the natural drainage system and outfall to the
Edmonds Way direct discharge basin. It also reduces the amount of impervious area
draining to the existing system by 1,942 sf.
SSMR #5 — Onsite Stormwater Management
Onsite Stormwater Management requirement for the three lots will be met by utilizing
onsite/LID techniques and infiltration as described in Chapter 5 of the City of Edmonds
Stormwater Supplement. Further detail will be provided at time of building permit when
the house footprint and driveway locations have been finalized. All pervious areas on site
will use compost amended soil per City of Edmonds Handout #E72 C.
It also should be noted that the project does not exceed the flow control threshold below
under SSMR #7 and has the opportunity to discharge additional flows to the Edmonds
Way Basin and stay under the flow control threshold. This may be considered during final
engineering.
SSMR #6 — Runoff Treatment
Proposed PGIS is less than the 5,000 sf threshold required for treatment.
SSMR #7 — Flow Control
Flow Control Facilities
The project is located within the Edmonds Way basin, which is a direct discharge basin.
Per Chapter 5.7.2 of the Edmonds 2010 manual, the flow control standard is as follows:
The post -development 10-, and 100- year recurrence interval peak flows shall not
exceed, 0.25 cfs and 0.45 cfs per acre of impervious surface area, respectively.
I'Plan.. Design. Maiiiage
CIVIL & 'S ITRUCT4JR:hL E 114GIINEE1RUNG 0 LAND SUMiiiYIMS, � LAND P11 MpNMI G
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2
Category 2 Small Site Drainage Report
Chung Short Plat
December 2016
By implementing LID components for all the impervious surfaces of the three lots (see
SSMR #5), the projects stormwater discharge is limited to the shared access roadway. It
is proposed to collect and convey water from the shared access to the existing 48" storm
main within SR -104. Utilizing WWHMv2012, it has been confirmed that the shared
driveway will not generate more than a 0.25 cfs and 0.45 cfs for the 10-, and 100 -
recurrence intervals. See the WWHM output below. A conveyance analysis of the new
conveyance system will be provided during Final Engineering.
WWHM2012
PROJECT REPORT
Project Name: default[23]
Site Name:
Site Address:
City
Report Date: 12/22/2016
Gage : Everett
Data Start : 1948/10/01
Data End : 2009/09/30
Precip Scale: 0.80
Version Date: 2016/02/25
Version : 4.2.12
Low Flow Threshold for POC 1 : 50 Percent of the 2 Year
High Flow Threshold for POC 1: 50 year
PREDEVELOPED LAND USE
Name : Basin 1
Bypass: No
Groundwater: No
Pervious Land Use acre
C, Forest, Mod .044
Pervious Total 0.044
Impervious Land Use acre
Impervious Total 0
Basin Total 0.044
Element Flows To:
Surface Interflow
Groundwater
11PIan- Design. Manage
C B/11— & STRUCTURAII.. ENG INElliiilft]flN(] I n...ANID SUF Vi. .:`fl[NG a LAND PP...ANNIING
3
Category 2 Small Site Drainage Report Chung Short Plat
December 2016
MITIGATED LAND USE
Name : Basin 1
Bypass: No
GroundWater: No
Pervious Land Use acre
Pervious Total
Impervious Land Use
'ROADS MOD
Impervious Total
Basin Total
Element Flows To:
Surface
Stream Protection Duration
Predeveloped Landuse Totals for POC #1
Total Pervious Area:0.044
Total Impervious Area:O
Mitigated Landuse Totals for POC #1
Total Pervious Area:O
Total Impervious Area:0.044
Groundwater
Flow Frequency Return Periods for Predeveloped. POC #1
Return Period
Flow(cfs)
2 year
0.000542
5 year
0.000847
10 year
0.001038
25 year
0 00,1259
50 year
0.00,141
100 year
0.001-55
Flow Frequency Return Periods for Mitigated. POC #1
Return Period
Flow(cfs)
2 year
0.,017484
5 year
0.023538
110 year
0.03°104'7
25 year
0.033994
50 year
0.038854
�100 year
0 0 4 4 () 31
Plan, Des-gn. Manage
CIVIL & STRUCR.)RA1. ENGINEHUNG 0 LAND SURVI - YING I LAND PLANNING
PROD CI` VANAGEMENF I PERVII EXPEDfFING I FEASIB11 [ f Y
n
Category 2 Small Site Drainage Report
Conveyance Analysis
Chung Short Plat
December 2016
A conveyance anslysis will be completed during final engineering to confirm the pipe
capacity of the proposed pipe against the projected design flows.
SSMR #8 — Wetland Protection
No known wetlands are located within 1/4 mile of the subject site.
SSMR #9 — Operation and Maintenance
Operation and Maintenance of all installed BMPs will be performed by the homeowners in
accordance with the provisions in Chapter 7 of the City of Edmonds Stormwater
Supplement.
SSMR #10 — Offsite Analysis and Mitigation
The existing downstream conveyance system was examined during the design process
and appears to be functioning properly. The project reduces the amount of impervious
surface draining to the existing system by 1,942 sf, so there are no adverse impacts
anticipated.
SSMR #11 — Financial Liability
Necessary performance bonds will be placed by the developer prior to construction.
S. Attachments
• VICINITY MAPS
• PROJECT CLASSIFICATION
DRAINAGE BASIN MAP
• NRCS SOILS REPORT
11)1 .n- Design. Maanage
CI/IL & SoTRUC; URAL. FO`G"dtl°VEEIRINGs I u.AEtD SGaiOdVQf` UJG:.; J h..IAND PII_Fl,MP+1 NG
PROJECT MANAGEN6l. NF I u'ERN✓V11 E..XPuiG.K:b]fJMS � f E:.:Ph"SSB u..I1-Y
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Category 2 Small Site Drainage Report
VICINITY MAPS
NTS
Chung Short Plat
December 2016
D.ky st
IF
MNAM
yw Pk
2241h 51 SW
T.
Edm-d. Way
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Plan Design. Marage
CIVIL & STRUCTURAL. EIJG1NE1.'.1RJNG I)LAIC ID SURVEYING ( LANC) PILAWIING
PROJECT MANAGEMEN r I IPERMIT EXPEDITING I FIFASIBIN ITY
6
2241h 51 SW
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4,
Plan Design. Marage
CIVIL & STRUCTURAL. EIJG1NE1.'.1RJNG I)LAIC ID SURVEYING ( LANC) PILAWIING
PROJECT MANAGEMEN r I IPERMIT EXPEDITING I FIFASIBIN ITY
6
Category 2 Small Site Drainage Report
Chung Short Plat
December 2016
I'PlIan.. Design. Manage
C'IML. & STRUCTURAL. EPIGMEIERING I LANID SURIVEYMG � IL.J IND PLAWNG
PROJECMANAGE.:.IMENI I PERMIT EXPECH I GNG I IFEASIBILATY
7
W,, �'. A
WAY,,
Category 2 Small Site Drainage Report
Chung Short Plat
December 2016
If you have determined that the Stormwater Manaacnient Code
applies to your proiect (Figure -A), follow the Blue boxes in the chart
I
Iviow to determine (lie Ckissil'ication ol'your project.
Does the project involve 1 -
acre
-acre or more of larid-
disturbing activity' ?
01,
Is the project part of a larger
common plan of development or
stile where the total disturbed area
for the entire plan will total I -acre
or more of land -disturbing activity?
W
Does the Project involve one or more of the
following:
.,000 square feet (sf) or nio.of rretr
-
iuiperyioris surface, regulated replaced
impervious surface or new plus regulated
replaced impenious surface?
OR
7,000 sf or more of laird -disturbing activity?
OR
50 cubic yards or more of either grading, fill, or
excavation as defined in Chapter 18.40,000
ECDC?
M
minor Site Project:
See Stormwater Supplement
Chapter 6 for specific
requirements
Y k�,�
Large Site Project:
See Stormwatersuppleirient
Chapter 4 for specific
requirements.
Does the project create or add 5,000 square feet or
more of new intperriorts surface, regulated
replaced impervious surface or new plus
regulated replaced impervious surface?
OR
Convert 3/4 acre or more of native vegetation to
lawn or landscaped area
OR
Through a combination of creating tqfeciive
impervious surface and converted pervious
surfaces, causes an increase of 0.1 cubic feet per
second in the 100 -year flow frequency from a
threshold discharge area as estimated using an
approved model"
W
Category I Small Site Project:
See Stormwater Supplement
Chapter 5 or specific
requirements
1P11, n- Desigri. Manage
CIVIL & SMUC.l URAL. ENG1NEF,,_R1,NG ! LAND SURIVE.�YING I LAND PLANNING
PRWECT IVU A F IIPERMI I EXPEM HM,; I FEASIBU.] FY
I
Yo,
Category 2Small Site Drainage Report Chung Short Plat
December 2016
DRAINAGE BASIN MAP
City ofEdmonds GIS
NTS
LU
CIA
lk
15
Yewy
VjN q,
IN 10/161 PROJECT SITE
71, EDMONDS WA
Al
Plan. Design. Mainage
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Category 2 Small Site Drainage Report
Chung Short Plat
December 2016
NRCS SOILS REPORT'
Plan.. Design. Manage
CIVIL & SI-RUCTURAL ENGIM . ERUNG I LAND SURVEYMG � h..OID PII...006ING
PROJEM MANAGEMENT I ung RIMI T E.:.XPEIDT.TMG � FIEiASIBILITY
10
USDA United States
Department of
Agriculture
MRCS
Natural
Resources
Conservation
Service
A product of the National
Cooperative Soil Survey,
a joint effort of the United
States Department of
Agriculture and other
Federal agencies, State
agencies including the
Agricultural Experiment
Stations, and local
participants
Custom Soil Resource
Report for
C% Snohomish County
Area, Washington
June 16, 2016
11 iG3 rrli�- I
Soil surveys contain information that affects land use planning in survey areas. They
highlight soil limitations that affect various land uses and provide information about
the properties of the soils in the survey areas. Soil surveys are designed for many
different users, including farmers, ranchers, foresters, agronomists, urban planners,
community officials, engineers, developers, builders, and home buyers. Also,
conservationists, teachers, students, and specialists in recreation, waste disposal,
and pollution control can use the surveys to help them understand, protect, or enhance
the environment.
Various land use regulations of Federal, State, and local governments may impose
special restrictions on land use or land treatment. Soil surveys identify soil properties
that are used in making various land use or land treatment decisions. The information
is intended to help the land users identify and reduce the effects of soil limitations on
various land uses. The landowner or user is responsible for identifying and complying
with existing laws and regulations.
Although soil survey information can be used for general farm, local, and wider area
planning, onsite investigation is needed to supplement this information in some cases.
Examples include soil quality assessments (http://www.nres.usda.gov/wps/portal/
nres/main/soils/health/) and certain conservation and engineering applications. For
more detailed information, contact your local USDA Service Center (http://
offices.sc.egov.usda.gov/locator/app?agency=nres) or your NRCS State Soil
Scientist (http://www.nres.usda.gov/wps/portal/nres/detail/soils/contactus/?
cid=nres142p2_053951).
Great differences in soil properties can occur within short distances. Some soils are
seasonally wet or subject to flooding. Some are too unstable to be used as a
foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic
tank absorption fields. A high water table makes a soil poorly suited to basements or
underground installations.
The National Cooperative Soil Survey is a joint effort of the United States Department
of Agriculture and other Federal agencies, State agencies including the Agricultural
Experiment Stations, and local agencies. The Natural Resources Conservation
Service (NRCS) has leadership for the Federal part of the National Cooperative Soil
S u rvey.
Information about soils is updated periodically. Updated information is available
through the NRCS Web Soil Survey, the site for official soil survey information.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs
and activities on the basis of race, color, national origin, age, disability, and where
applicable, sex, marital status, familial status, parental status, religion, sexual
orientation, genetic information, political beliefs, reprisal, or because all or a part of an
individual's income is derived from any public assistance program. (Not all prohibited
bases apply to all programs.) Persons with disabilities who require alternative means
2
for communication of program information (Braille, large print, audiotape, etc.) should
contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a
complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400
Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272
(voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and
employer.
3
Preface........................................................................................... .
How Soil Surveys Are Made..........................................................
SoilMap..........................................................................................
SoilMap........................................................................................
Legend..........................................................................................
MapUnit Legend..........................................................................
Map Unit Descriptions..................................................................
Snohomish County Area, Washington ......................................
17—Everett very gravelly sandy loam, 0 to 8 percent slopes
References ..........
4
How Soil Surveys Are Made
Soil surveys are made to provide information about the soils and miscellaneous areas
in a specific area. They include a description of the soils and miscellaneous areas and
their location on the landscape and tables that show soil properties and limitations
affecting various uses. Soil scientists observed the steepness, length, and shape of
the slopes; the general pattern of drainage; the kinds of crops and native plants; and
the kinds of bedrock. They observed and described many soil profiles. A soil profile is
the sequence of natural layers, or horizons, in a soil. The profile extends from the
surface down into the unconsolidated material in which the soil formed or from the
surface down to bedrock. The unconsolidated material is devoid of roots and other
living organisms and has not been changed by other biological activity.
Currently, soils are mapped according to the boundaries of major land resource areas
(MLRAs). MLRAs are geographically associated land resource units that share
common characteristics related to physiography, geology, climate, water resources,
soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically
consist of parts of one or more MLRA.
The soils and miscellaneous areas in a survey area occur in an orderly pattern that is
related to the geology, landforms, relief, climate, and natural vegetation of the area.
Each kind of soil and miscellaneous area is associated with a particular kind of
landform or with a segment of the landform. By observing the soils and miscellaneous
areas in the survey area and relating their position to specific segments of the
landform, a soil scientist develops a concept, or model, of how they were formed. Thus,
during mapping, this model enables the soil scientist to predict with a considerable
degree of accuracy the kind of soil or miscellaneous area at a specific location on the
landscape.
Commonly, individual soils on the landscape merge into one another as their
characteristics gradually change. To construct an accurate soil map, however, soil
scientists must determine the boundaries between the soils. They can observe only
a limited number of soil profiles. Nevertheless, these observations, supplemented by
an understanding of the soil -vegetation -landscape relationship, are sufficient to verify
predictions of the kinds of soil in an area and to determine the boundaries.
Soil scientists recorded the characteristics of the soil profiles that they studied. They
noted soil color, texture, size and shape of soil aggregates, kind and amount of rock
fragments, distribution of plant roots, reaction, and other features that enable them to
identify soils. After describing the soils in the survey area and determining their
properties, the soil scientists assigned the soils to taxonomic classes (units).
Taxonomic classes are concepts. Each taxonomic class has a set of soil
characteristics with precisely defined limits. The classes are used as a basis for
comparison to classify soils systematically. Soil taxonomy, the system of taxonomic
classification used in the United States, is based mainly on the kind and character of
soil properties and the arrangement of horizons within the profile. After the soil
scientists classified and named the soils in the survey area, they compared the
Custom Soil Resource Report
individual soils with similar soils in the same taxonomic class in other areas so that
they could confirm data and assemble additional data based on experience and
research.
The objective of soil mapping is not to delineate pure map unit components; the
objective is to separate the landscape into landforms or landform segments that have
similar use and management requirements. Each map unit is defined by a unique
combination of soil components and/or miscellaneous areas in predictable
proportions. Some components may be highly contrasting to the other components of
the map unit. The presence of minor components in a map unit in no way diminishes
the usefulness or accuracy of the data. The delineation of such landforms and
landform segments on the map provides sufficient information for the development of
resource plans. If intensive use of small areas is planned, onsite investigation is
needed to define and locate the soils and miscellaneous areas.
Soil scientists make many field observations in the process of producing a soil map.
The frequency of observation is dependent upon several factors, including scale of
mapping, intensity of mapping, design of map units, complexity of the landscape, and
experience of the soil scientist. Observations are made to test and refine the soil -
landscape model and predictions and to verify the classification of the soils at specific
locations. Once the soil -landscape model is refined, a significantly smaller number of
measurements of individual soil properties are made and recorded. These
measurements may include field measurements, such as those for color, depth to
bedrock, and texture, and laboratory measurements, such as those for content of
sand, silt, clay, salt, and other components. Properties of each soil typically vary from
one point to another across the landscape.
Observations for map unit components are aggregated to develop ranges of
characteristics for the components. The aggregated values are presented. Direct
measurements do not exist for every property presented for every map unit
component. Values for some properties are estimated from combinations of other
properties.
While a soil survey is in progress, samples of some of the soils in the area generally
are collected for laboratory analyses and for engineering tests. Soil scientists interpret
the data from these analyses and tests as well as the field -observed characteristics
and the soil properties to determine the expected behavior of the soils under different
uses. Interpretations for all of the soils are field tested through observation of the soils
in different uses and under different levels of management. Some interpretations are
modified to fit local conditions, and some new interpretations are developed to meet
local needs. Data are assembled from other sources, such as research information,
production records, and field experience of specialists. For example, data on crop
yields under defined levels of management are assembled from farm records and from
field or plot experiments on the same kinds of soil.
Predictions about soil behavior are based not only on soil properties but also on such
variables as climate and biological activity. Soil conditions are predictable over long
periods of time, but they are not predictable from year to year. For example, soil
scientists can predict with a fairly high degree of accuracy that a given soil will have
a high water table within certain depths in most years, but they cannot predict that a
high water table will always be at a specific level in the soil on a specific date.
After soil scientists located and identified the significant natural bodies of soil in the
survey area, they drew the boundaries of these bodies on aerial photographs and
identified each as a specific map unit. Aerial photographs show trees, buildings, fields,
roads, and rivers, all of which help in locating boundaries accurately.
A
The soil map section includes the soil map for the defined area of interest, a list of soil
map units on the map and extent of each map unit, and cartographic symbols
displayed on the map. Also presented are various metadata about data used to
produce the map, and a description of each soil map unit.
7
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Custom Soil Resource Report
'tap Unit Legend
Map Unit Symbol
17
Totals for Area of Interest
Snohomish County Area, Washington (WA661)
Map Unit Name i Acres In AOI
Everett very gravelly sandy
loam, 0 to 8 percent slopes
IMap Unit Descriptions
Percent of A01
0.4 100.0%
0,4 100.0%
The map units delineated on the detailed soil maps in a soil survey represent the soils
or miscellaneous areas in the survey area. The map unit descriptions, along with the
maps, can be used to determine the composition and properties of a unit.
A map unit delineation on a soil map represents an area dominated by one or more
major kinds of soil or miscellaneous areas. A map unit is identified and named
according to the taxonomic classification of the dominant soils. Within a taxonomic
class there are precisely defined limits for the properties of the soils. On the landscape,
however, the soils are natural phenomena, and they have the characteristic variability
of all natural phenomena. Thus, the range of some observed properties may extend
beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic
class rarely, if ever, can be mapped without including areas of other taxonomic
classes. Consequently, every map unit is made up of the soils or miscellaneous areas
for which it is named and some minor components that belong to taxonomic classes
other than those of the major soils.
Most minor soils have properties similar to those of the dominant soil or soils in the
map unit, and thus they do not affect use and management. These are called
noncontrasting, or similar, components. They may or may not be mentioned in a
particular map unit description. Other minor components, however, have properties
and behavioral characteristics divergent enough to affect use or to require different
management. These are called contrasting, or dissimilar, components. They generally
are in small areas and could not be mapped separately because of the scale used.
Some small areas of strongly contrasting soils or miscellaneous areas are identified
by a special symbol on the maps. If included in the database for a given area, the
contrasting minor components are identified in the map unit descriptions along with
some characteristics of each. A few areas of minor components may not have been
observed, and consequently they are not mentioned in the descriptions, especially
where the pattern was so complex that it was impractical to make enough observations
to identify all the soils and miscellaneous areas on the landscape.
The presence of minor components in a map unit in no way diminishes the usefulness
or accuracy of the data. The objective of mapping is not to delineate pure taxonomic
classes but rather to separate the landscape into landforms or landform segments that
have similar use and management requirements. The delineation of such segments
on the map provides sufficient information for the development of resource plans. If
intensive use of small areas is planned, however, onsite investigation is needed to
define and locate the soils and miscellaneous areas.
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Custom Soil Resource Report
An identifying symbol precedes the map unit name in the map unit descriptions. Each
description includes general facts about the unit and gives important soil properties
and qualities.
Soils that have profiles that are almost alike make up a soil series. Except for
differences in texture of the surface layer, all the soils of a series have major horizons
that are similar in composition, thickness, and arrangement.
Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity,
degree of erosion, and other characteristics that affect their use. On the basis of such
differences, a soil series is divided into soil phases. Most of the areas shown on the
detailed soil maps are phases of soil series. The name of a soil phase commonly
indicates a feature that affects use or management. For example, Alpha silt loam, 0
to 2 percent slopes, is a phase of the Alpha series.
Some map units are made up of two or more major soils or miscellaneous areas.
These map units are complexes, associations, orundifferentiatedgroups.
A complex consists of two or more soils or miscellaneous areas in such an intricate
pattern or in such small areas that they cannot be shown separately on the maps. The
pattern and proportion of the soils or miscellaneous areas are somewhat similar in all
areas. Alpha -Beta complex, 0 to 6 percent slopes, is an example.
An association is made up of two or more geographically associated soils or
miscellaneous areas that are shown as one unit on the maps. Because of present or
anticipated uses of the map units in the survey area, it was not considered practical
or necessary to map the soils or miscellaneous areas separately. The pattern and
relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha -
Beta association, 0 to 2 percent slopes, is an example.
An undifferentiated group is made up of two or more soils or miscellaneous areas that
could be mapped individually but are mapped as one unit because similar
interpretations can be made for use and management. The pattern and proportion of
the soils or miscellaneous areas in a mapped area are not uniform. An area can be
made up of only one of the major soils or miscellaneous areas, or it can be made up
of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example.
Some surveys include miscellaneous areas. Such areas have little or no soil material
and support little or no vegetation. Rock outcrop is an example.
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Custom Soil Resource Report
Snohomish County Area, Washington
17—Everett very gravelly sandy loam, 0 to 8 percent slopes
Map Unit Setting
National map unit symbol: 2t629
Elevation: 30 to 900 feet
Mean annual precipitation: 35 to 91 inches
Mean annual air temperature: 48 to 52 degrees F
Frost -free period: 180 to 240 days
Farmland classification: Farmland of statewide importance
Map Unit Composition
Everett and similar soils: 80 percent
Minor components: 20 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Everett
Setting
Landform: Eskers, kames, moraines
Landform position (two-dimensional): Shoulder, summit
Landform position (three-dimensional): Crest, interfluve
Down-slope shape: Convex
Across -slope shape: Convex
Parent material: Sandy and gravelly glacial outwash
Typical profile
Oi - 0 to 1 inches: slightly decomposed plant material
A - 1 to 3 inches: very gravelly sandy loam
Bw - 3 to 24 inches: very gravelly sandy loam
C1 - 24 to 35 inches: very gravelly loamy sand
C2 - 35 to 60 inches: extremely cobbly coarse sand
Properties and qualities
Slope: 0 to 8 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Somewhat excessively drained
Capacity of the most limiting layer to transmit water (Ksat): High (1.98 to 5.95 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Available water storage in profile: Low (about 3.2 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 4s
Hydrologic Soil Group: A
Other vegetative classification: Droughty Soils (G002XS401 WA), Droughty Soils
(G002XF403WA), Droughty Soils (G002XN402WA)
Minor Components
Alderwood
Percent of map unit: 10 percent
Landform: Ridges, hills
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Custom Soil Resource Report
Landform position (two-dimensional): Summit
Landform position (three-dimensional): Crest, talf
Down-slope shape: Linear, convex
Across -slope shape: Convex
Indianola
Percent of map unit: 10 percent
Landform: Eskers, kames, terraces
Landform position (three-dimensional): Tread
Down-slope shape: Linear
Across -slope shape: Linear
13
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Standard specifications for transportation materials and methods of sampling and
testing. 24th edition.
American Society for Testing and Materials (ASTM). 2005. Standard classification of
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Federal Register. July 13, 1994. Changes in hydric soils of the United States.
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in the United States.
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nres/detail/national/soils/?cid=n res142p2_053577
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portal/nres/detail/national/soils/?cid=nres142p2_053580
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home/?cid=nres142p2_053374
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detail/national/landuse/rangepasture/?cid=stelprdb1043084
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Custom Soil Resource Report
United States Department of Agriculture, Natural Resources Conservation Service.
National soil survey handbook, title 430 -VI. http://www.nres.usda.gov/wps/portal/
nres/detail/soils/scientists/?cid=nres142p2_054242
United States Department of Agriculture, Natural Resources Conservation Service.
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Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296.
http://www. nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?
cid=nres 142 p2_053624
United States Department of Agriculture, Soil Conservation Service. 1961. Land
capability classification. U.S. Department of Agriculture Handbook 210. http://
www.nrcs.usda.gov/lnternet/FSE—DOCUMENTS/nrcsl 42p2_052290.pdf
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