HomeMy WebLinkAboutMiscAmends ORD: 4056, 4269
4835, 4851
4963, 5100
CITY OF RENTON, WASHINGTON
ORDINANCE NO. 5132
AN ORDINANCE OF THE CITY OF RENTON, WASHINGTON,
AMENDING CHAPTER 4-2, ZONING DISTRICTS — USES AND
STANDARDS, CHAPTER 4-39 ENVIRONMENTAL REGULATIONS AND
OVERLAY DISTRICTS, CHAPTER 44, CITY-WIDE PROPERTY
DEVELOPMENT STANDARDS, CHAPTER 4-6, STREET AND UTILITY
STANDARDS, AND CHAPTER 4.11, DEFINITIONS, OF TITLE IV
(DEVELOPMENT REGULATIONS) OF ORDINANCE NO. 4260
ENTITLED "CODE OF GENERAL ORDINANCES OF THE CITY OF
RENTON, WASHINGTON" TO AMEND THE R-1 RESIDENTIAL LOW
DENSITY ZONE IN ORDER TO REGULATE CLUSTERED
DEVELOPMENT AND CREATE AN URBAN SEPARATOR OVERLAY
DESIGNATION.
WHEREAS, the King County Countywide Planning Policies designate certain, properties
in the County as "Urban Separators"; and
WHEREAS, Countywide Planning Policy LU-27 calls for the preservation of urban
separators as permanent low density lands which protect adjacent resource lands, Rural Areas,
and environmentally sensitive areas; and
WHEREAS, Urban Separators are intended to create open space corridors within and
between Urban Areas which provide environmental, visual, recreational and wildlife benefits;
and
WHEREAS, Countywide Planning Policy LU-27 establishes that maintenance of urban
separators is a regional as well as local concern and further provides that modifications to
development regulations should have King County review and concurrence; and
WHEREAS, the City of Renton has coordinated review of the proposed Urban Separator
regulations with King County staff and elected officials; and
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ORDINANCE NO. 51 3 2
WHEREAS, applicable Metropolitan. King County Code, Title 21 A.12.030.17,
establishes standards within R-1 zoning, including a fifty percent contiguous open space
requirement and mandatory clustered development outside these corridors; and
WHEREAS, the City Council adopted Community Design Element policies that
designate certain low -density residential and resource areas as Urban Separators, to provide
physical and visual distinctions between Renton and adjacent communities, and to define
Renton's boundaries; and
WHEREAS, the City Council created a Residential Love Density Designation to map
Urban Separators; and
WHEREAS, the Renton City Council determined that Renton development standards
should address the same or better level of protection for Urban Separators as is provided by King
County regulations;
NOW, THEREFORE, THE CITY COUNCIL OF THE CITY OF RENTON,
WASHINGTON, DOES ORDAIN AS FOLLOWS:
SECTION I. Section 4-2-110.A, Development Standards for Single Family
Residential Zoning Designations, of Chapter 2, Zoning Districts — Uses and Standards, of Title
IV (Development Regulations) of Ordinance No. 4260 entitled "Code of General Ordinances of
the City of Renton, Washington" is hereby amended to read as shown on Exhibit A.
SECTION H. Subsection 4-2-110.D.3 of Section 4-2-110.1), Conditions
Associated with Development Standards Table for Single Family Residential Zoning
Designations, of Chapter 2, Zoning Districts — Uses and Standards, of Title IV (Development
Regulations) of Ordinance No, 4260 entitled "Code of General Ordinances of the City of Renton,
Washington" is hereby amended, to read as follows:
2
ORDINANCE NO. 5132
3. Clustering is allowed to meet objectives such as preserving significant natural
features, providing neighborhood open space, or facilitating the provision of sewer service.
Within designated urban separators, clustering is required, consistent with the provision of
Section 4-3-110, Urban Separator Overlay Regulations.
a. The maximum net density requirement shall not be exceeded except that
within Urban Separators a density bonus may be granted allowing the total density to achieve
one dwelling unit per gross contiguous acre for projects that meet the following criteria.
(1) Provision of native vegetation cover on 65% of the gross area of all
parcels in the land use action, including both the area within and outside the open space corridor,
with either existing or new vegetative cover, and at least one of the following additional criteria.
(i) Enhancement of wetlands is provided at a ratio of one-half
acre enhanced for one acre delineated within the Urban Separator pursuant to Section 4-3-050M
12b. Evaluation Criteria, and Section 4-3-050M 12.c. Wetlands Chosen for Enhancement.
Enhancement proposed for a density bonus may not also be used for a mitigation for other
wetland alterations.
(ii) Legal non -conforming uses are removed from the site
and/or brought into conformance with Renton standards.
(iii) Natural surface pedestrian trails, with public access, are
provided as part of an adopted trail system or, where there is no planned trail system, in a
configuration approved by the Reviewing Officiai.
(iv) In the absence of either wetlands or legal non -conforming
uses on the site, public access and trails shall be required to the satisfaction of the Reviewing
Official.
3
ORDINANCE No 513 2
(2) Parcels within the Urban Separator may be combined into larger
contiguous holdings to allow platting to achieve bonus density, however existing legal lots shall
not be reduced in land area for the purpose of transferring density unless such lots are included in
a proposed plat
b. The area of individual lots shall not be less than 10,000 sq. ft.
SECTION III. A new Section, 4-3-110, of Chapter 4-3, Environmental
Regulations and Overlay Districts, of Title IV (Development Regulations) of Ordinance No.
4260 entitled "Code of General Ordinances of the City of Renton, Washington" is hereby added,
to read as follows:
4-3-110 URBAN SEPARATOR OVERLAY REGULATIONS:
A. PURPOSE: The purpose of this section is to implement the Urban Separators policies in
the Community Design Element of the Comprehensive Plan and the King County Countywide
Planning Policies. The intent is to provide physical and visual distinctions between Renton and
adjacent communities, define Renton's boundaries and create contiguous open space corridors
within and between urban communities, which provide environmental, visual, recreational and
wildlife benefits. Urban Separators shall be permanent low -density lands that protect resources
and environmentally sensitive areas.
B. APPLICABILITY: This section shall apply to subdivisions and building permits on
lands within designated Urban Separators as shown in the Urban Separators Maps.
C. URBAN SEPARATORS MAPS:
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ORDINANCE NO. 5132
V�Y Rd
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ORDINANCE NO. 5132
2. Talbot Urban Separator
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P
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Talbot Urban Separator
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It
ORDINANCE NO. 5132
D. ADMINISTRATION:
1. Review Process: Applications subject to Urban Separator Regulations shall be
processed as a component of the governing land use process.
2. Authority: The Reviewing Official shall have the authority to approve with
conditions, or deny proposals based on the provisions of the Urban Separator Overlay
Regulations.
E. URBAN SEPARATOR OVERLAY REGULATIONS:
i. Contiguous Open Space Corridor Established.
A designated contiguous open space corridor is established as shown on the Urban
Separators Overlay Map in Section 4-3-110J.
2. Dedication of Open Space Required.
a. Approval of a plat, and/or building permit on an undeveloped legal lot in
the Urban Separator Overlay shall require dedication of 50°fo of the gross land area of the parcel
or parcels as a non -revocable open space tract retained by property owner, or dedicated to a
homeowners association or other suitable organization as determined by the Reviewing Official.
Acreage in tracts may include critical areas and/or critical area buffers. At a minimum, open
space shall be connected to another contiguous open space parcel by a fifty foot (50') corridor.
b. Existing residences, existing accessory uses and structures, existing above
ground utilities located in the tract at the time of designation and new small and medium utilities
shall not count toward the 50% gross land area calculation for open space except for storm water
ponds designed with less than 3: l engineered slopes and enhanced per techniques and landscape
requirements set forth in the publication the "integrated Pond" King County Land and Water
Resources Division.
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ORDINANCE NO. 5132
C. Approval of a building permit for an addition of 300 square feet for a
primary use structure or 500 square feet for an accessory structure shall require recordation of a
conservation easement, protective easement or tract and deed restriction on critical areas and
critical area buffers located within the Contiguous Open Space Corridor pursuant to Section 4-3-
050.G, Native Growth Protection Areas.
d. Land dedicated as open space shall be located within the mapped
Contiguous Open Space Corridor unless a modification is approved pursuant to Section 4-3-
110.B.6.
3. Uses Allowed 1n Contiguous Open Space.
a. Passive Recreation with no development of active recreation facilities
except within a municipal park.
b. Natural surface pedestrian trails.
C. Animal husbandry (small, medium and large) provided that fencing is
subject to the conditions in 4-3-110.E.3.g, below.
d. Existing residences and accessory uses and structures.
e. Small and medium utilities and large underground utilities.
£ Access Easements.
(1) Utilities easements and emergency service access roads may be
located within Contiguous Open Space Corridors for the limited purpose of providing service to
parcels platted after March 2005, for which there is no practical alternative way to provide
service. Utilities and emergency service easements shall be developed with permeable surface
treatment.
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ORDINANCE NO. 5132
(2) Private access easements for ingress and egress may be located within
Contiguous Open Space in the limited instance where there is no alternative access to a pre-
existing legal lot, but shall not serve lots platted after March 2005.
g. Fencing or similar structures and/or hedges or similar landscape
features on the property or easement boundary of properties abutting and within the Contiguous
Open Space Corridor shall not create a solid barrier. Where required to protect wetlands
pursuant to Section 4-3-050.M.7.c, fencing shall be the minimum necessary.
4. Uses in Portions of the Urban Separator Outside the Established Contiguous Open
Space Corridor.
a. Lases shall be consistent with Section 4-2-060 and 4-2-070.B.
Residential-1 Zone, one dwelling unit per net acre.
b. Development shall be clustered outside the Contiguous Open Space
Corridor mapped in 2-3-110.J.
5. Standards Within Entire Urban Separator.
a. Forest/vegetation clearing shall be limited to a maximum of 35% of the
gross acreage of the site except:
(1) The percentage of forestivegetation coverage may be increased to
qualify for the density bonus allowed in Section 4-2-110.D.
(2) The Reviewing Official may modify the percentage of
forest/vegetation retention if determined necessary to meet the surface water retention/detention
standards of Section 4-3-110.E-7.
(3) The Reviewing Official may approve forest/vegetation clearing
greater than 35% of individual building sites to allow grading for a home site provided that:
0
ORDINANCE NO. 5 t 3 2
(i) A landscape plan is provided for each building site showing
compensating re -planting of species with the same or better water retention and erosion control
fuunctions.
(ii) 5% additional replacement landscaping per site is provided
(iii) Plant caliper is determined by the Reviewing Official to be
sufficient to achieve needed water retention and erosion control functions, and
(iv) Individual trees or stands of trees are retained when
feasible. Feasibility is defined as locations and tree health sufficient to ensure continued viability
of the tree and safety of structures within the developed portion of the lot and
(v) The landscape plan provides massing of plant material to
create either a connection to required open space or is of sufficient size to create functional
wildlife habitat.
b. If the existing cleared area of a site, as of March 21, 2005 is greater
than 35%, approval of a plat shall require re -planting of forest/vegetative cover.
C. Forest/vegetation cover may include a combination of Northwest
native vegetation including conifer, deciduous trees and shrubs sufficient to provide water
retention and erosion control, as determined appropriate by the Reviewing Official. The
Reviewing Official shall determine whether existing vegetation provides functions to meet
forest/vegetation coverage standards, and shall require additional plantings if existing vegetation
is found to be insufficient.
d. Stormwater management shall comply with the 2005 King County
Surface Water Design Manual Conservation Flow Control Area Level 2 flow control standards.
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ORDINANCE NO. 5132
e. Private access easements and improvements shall be established at
the minimum standard needed to meet public safety requirements.
£ Landscape plans required in Section 4-4-070 shall include
retention/re-planting plans as applicable, consistent with standards and plant lists in King County
Department of Natural Resources and Parks Water and Land Resources Division Publication
"Going Native."
6. Modification of Mapped Contiguous Open Space.
The Reviewing Official may modify the open space configuration where:
a Site specific data confirms that the adopted Contiguous Open Space
Corridor map includes more than the required gross area for any parcel, or
b. The applicant can demonstrate a configuration of contiguous open space
that provides better or equal provision of the open space requirement. Modifications to the
Contiguous Open Space Corridor shall be re -mapped during the City's annual Title IV review
process.
SECMDN IV, Section 4-4-0403 of Chapter 4, City -Wide Property Development
Standards, of Title IV (Development Regulations) of Ordinance No. 4260 entitled "Code of
General Ordinances of the City of Renton, Washington" is hereby amended to read as follows:
B. APPLICABILITY. The provisions and conditions of this Section regulating
height are not applicable to fences or barriers required by state law or by the zoning provisions of
the Code to surround and enclose public safety installations, school grounds, public playgrounds,
private or public swimming pools and similar installations and improvements.
Fences, and hedges within the Urban Separator Overlay are also subject to requirements
of the Urban Separator Overlay Regulations (see Section 4-3-110).
I
ORDINANCE NO. 5132
SECTION V. Section 4-4-130.0 of Chapter 4, City -Wide Property Development
Standards, of Title IV (Development Regulations) of Ordinance No. 4260 entitled "Code of
General Ordinances of the City of Renton, Washington" is hereby amended to read as follows.
C. ALLOWABLE TREE CUTTING ACTIVITIES.
Tree cutting and associated use of mechanical equipment is permitted as follows, except
as provided in subsection D.2 of this Section, restrictions for Critical Areas, and in Section 4-3-
I IO.E.5.b, Urban Separator Overlay Regulations.
Emergency Situations: Removal of trees and/or ground cover by the City and/or
public or private utility in emergency situations involving immediate danger to life or property,
substantial fire hazards, or interruption of services provided by a utility.
2. Dead, Dangerous, or Diseased Trees: Removal of dead, terminally diseased,
damaged, or dangerous ground cover or trees which have been certified prior to removal as such
by a forester, registered landscape architect, or certified arborist, selection of whom to be
approved by the City based on the type of information required, or the removal of which is
approved by the City. 3. Maintenance Activities/Essential Tree Removal — Public or Private
Utilities, Roads and Public Parks: Maintenance activities including routine vegetation
management and essential tree removal for public and private utilities, road rights -of -way and
easements, and parks.
4. Installation of SEPA Exempt Public or Private Utilities: Installation of
distribution lines by public and private utilities provided that such activities are categorically
exempt from the provisions of the State Environmental Policy Act and RMC 4-9-070,
Environmental Review Procedures.
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ORDINANCE NO. 5132
5. Existing and Ongoing Agricultural Activities: Clearing associated with existing
and ongoing agricultural activities as defined in chapter 4-11 RMC, Definitions.
b. Commercial Nurseries or Tree Farms: Clearing or cutting of only those trees
which are planted and growing on the premises of a licensed retailer or wholesaler.
7. Public Road Expansion: Expansion of public roads.
8. Site Investigative Work: Site investigative work necessary for land use
application submittals such as surveys, soil logs, percolation tests, and other related activities
including the use of mechanical equipment to perform site investigative work provided the work
is conducted in accordance with the following requirements.
a. Investigative work should not disturb any more than five percent (5%) of
any protected sensitive area described in subsection D.2 of this Section, Restrictions for Critical
Areas, on the subject property. In every case impacts shall be minimized and disturbed areas
restored.
b. In every location where site investigative work is conducted, disturbed
areas shall be minimized, and immediately restored.
C. A notice shall be posted on the site by the property owner or owner's
agent indicating that site investigative work is being conducted, and that the work must minimize
disturbance to the critical areas identified in subsection D.2 of this Section, Restrictions for
Critical Areas.
d. No site investigative work shall commence without first notifying the
Director or his or her designee in advance.
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ORDINANCE NO. 5132
9. Allowable Minor Tree Cutting Activities: Tree cutting and associated use of
mechanical equipment is permitted as follows, except as provided in subsection D2 of this
Section, Restrictions for Critical Areas:
a. On a developed lot or on a partially developed lot less than one-half (1/2)
of an acre any number of trees may be removed;
b. On a partially developed lot greater than one-half (1/2) of an acre or on an
undeveloped lot provided that:
i. No more than three (3) trees are removed in any twelve (12) month
period from a property under thirty five thousand (35,000) square feet in size; and
ii. No more than six (b) trees are removed in any twelve (12) month
period from a property over thirty five thousand (35,000) square feet in size.
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iii. Rights -of -Way Unobstructed: In conducting minor tree cutting
activities, rights -of -way shall not be obstructed.
10. Landscaping or Gardening Permitted: Land clearing in conformance with the
provisions of subsection C.9 of this Section, Allowable Tree Cutting Activities, and subsection
D.2, Restrictions for Critical Areas, is permitted on a developed lot for purposes of landscaping
or gardening. Land clearing in conformance with the provisions of subsection C.9, Allowable
Minor Tree Cutting Activities, and subsection D.2, Restrictions for Critical Areas, is permitted
14
ORDINANCE NO. 5132
on a partially developed or undeveloped lot for purposes of landscaping or gardening provided
that no mechanical equipment is used.
11. Operational Mining/Quarrying: Land clearing and tree cutting associated with
previously approved, operational mining and quarrying activities.
12. Modification of Existing Utilities and Streets (not otherwise exempted by RMC 4-
3-050.C.7) by Ten Percent (10%) or Less: Overbuilding (enlargement beyond existing project
needs) or replacement and/or rehabilitation of existing streets, provided the work does not
increase the footprint of the structure, line or street by more than ten percent (10%) within the
critical area and/or buffer areas.
SECTION VL Section 4-6-030.F of Chapter 6, Street and Utility Standards, of
Title fV (Development Regulations) of Ordinance No. 4260 entitled "Code of General
Ordinances of the City of Renton, Washington" is hereby amended to read as follows:
F. DRAINAGE PLAN DESIGN CRITERIA, DRAFTING STANDARDS AND
CONTENTS:
The drainage plan shall be prepared in conformance with the Department's construction
plan drafting standards and contents, the City's Standard Specifications for Municipal
Construction and Standard Detail documents, and the design criteria, construction materials,
practices and standard details contained in chapters 3, 4, and 5 of the current King County
Surface water design manual; provided that the Department's standards and design criteria will
take precedence and prevail in any interpretation of conflicting or contradictory standards and
design criteria, and provided, further, that within designated Urban Separators regulated in
Section 4-4-110, the 2005 King County Surface Water Design Manual Conservation Flow
Control Area Level 2 flow control standards are required.
15
ORDINANCE NO. 5132
SECTION VI. Section 4-11-150.0 of Chapter 11, Definitions, of Title IV
(Development Regulations) of Ordinance No. 4260 entitled "Code of General Ordinances of the
City of Renton, Washington" is hereby amended by adding the following definition of Open
Space, Contiguous, Urban Separator, to read as follows:
Open Space, Contiguous, Urban Separator: band permanently set aside as open space
located in recorded tracts. Contiguous open space lands may include critical areas, such as
wetlands and steep slopes, and wetland buffers, as well as stormwater ponds enhanced per the
techniques and landscape requirements set forth in The Integrated Pond, Ding County Water and
Land Resources Division.
SECTION VII. This ordinance shall be effective upon its passage, approval, and
five days after its publication.
PASSED BY THE CITY COUNCIL this 4 th _ day of April � , 2005.
APPROVED BY THE MAYOR this 4 th
AppFoyeo as to form:
Lawrence J. Warren, Attorney
Date of Publication: 4/ 8/ 2 0 0 5 (summary)
ORD.I 1753/24/05:ma
Bonnie 1. Walton, City Cleric
day of April 2005.
�4 g -�
"-ka-
Kathy K olker-Wheeler, Mayor
16
ORDINANCE NO. 5132
Exhibit A
4-2-110A DEVELOPMENT STANDARDS FOR SINGLE FAMILY RESIDENTIAL ZONING
DESIGNATIONS
(Primary and Attached Accessory Structures)
RC R-1 R-4 R-8
DENSITY Net D.ehgity in Dwell! g Units per Net Acre)
Minimum
None
None
None
4 dwelling units
Housing Density
per net acre''2
for proposed short
plats or
subdivisions
Maximum
1 dwelling unit
1 dwelling unit per
4 dwelling units
8 dwelling units
z
Housing Density
per 10 net
1 net acre except
73
per 1 net acre
per 1 net acre
acres
that in designated
Urban Separators,
density of up to 1
unit per gross
acre may be
permitted subject
to conditions in
RMG 4-3-110
Urban Separator
Overlay.
NUMBER OF DWELLING
UNITS PER .LOT
Maximum
1 dwelling with
1 dwelling unit
1 dwelling unit
1 dwelling unit
Number per legal
1 accessory
Joe
unit
LOT DIMENSIONS
Minimum Lot
10 acres
1 acre
8,000 sq. ft.
4,500 sq. ft. for
Size for lots
10,000 sq. ft. for
except where
parcels greater
created after
cluster
small lot
than 1 acre.
!November 10,
development3
clusters1' are
2004
allowed, R-8
5,000 sq. ft. for
standards shall
parcels 1 acre or
apply.
less.
Minimum Lot
150 ft. for
75 ft. for interior
70 ft. for interior
50 ft. for interior
Width for lots
interior lots.
lots.
lots. 80 ft, for
lots.
created after
corner lots."' i3
November 10,
175 ft. for
85 ft, for corner
except where
60 ft. for corner
2004
corner lots.
lots.
small lot
lots
Except for
clusters40 are
clustered
allowed, R-8
development
standards shall
within designated
apply.
Urban Separators
R-4 standards
shall apply for
both interior and
corner lots.
Minimum Lot
200 ft.
85 ft.
80 ft. except
65 ft.
Depth for lots
where small lot
created after
clustersi0 are
November 10,
allowed, R-8
2004
standards shall
apply.
Page 1 of 5
ORDINANCE NO. 5132
Exhibit A
R C R-1 R-4 R-8
SETBACKS
Minimum Front
30 ft.5
30 ft_ b30
ft. except
15 ft. for primary
Yard
where small lot
structure.
clusters'0 are
allowed, R-8
20 ft. for attached
standards shall
garages accessed
apply.
from front or side
Unit with Alley
yard street.
Access
Unit with Alley
Garage: The
Access Garage:
front yard set-
The front yard
back of the
set -back of the
primary
primary structure
structure may
may be reduced
be reduced to
to 10 ft. if all
20 ft. if all
parking is
parking is
provided in the
provided in the
rear yard of the lot
rear yard of the
with access from
lot with access
a public right -of -
from a public
way or alley. s
right-of-way or
alley. 6
Minimum Side
30 ft.
20 ft.
20 ft. except
15 ft. for the
Yard Along a
where small lot
primary structure
Street
clusters'0 are
and 20 ft. for the
allowed, 15 ft. is
attached garages
allowed.
which access
from the front and
side yard along a
street.
Minimum Side
25 ft.
15 ft,
15 combined
5 ft.
Yard
ft. 12, 13 are
allowed with a
minimum of 5 ft.
for any side
yard, except
where small lot
clusters 10 are
allowed, 5 ft.
Page 2 of 5
ORDINANCE NO. 5132
Exhibit A
RC R-1 R-4 R-8
SETBACKS Continued
Minimum Rear
35 ft.
25 ft.
25 ft.
20 ft.
Yard
Where small lot
clusters1° are
allowed, 20 ft.
Clear Vision Area
In no case shall
In no case shall
In no case shall
In no case shall a
a structure over
a structure over
a structure over
structure over 42
42 in. in height
42 in. in height
42 in. in height
in. in height
intrude into the
intrude into the
intrude into the
intrude into the
20 ft. clear
20 ft. clear
20 ft. clear
20 ft. clear vision
vision area
vision area
vision area
area defined in
defined in RMC
defined in RMC
defined in RMC
RMC 4-11-030.
4-11-030.
4-11-030.
4-11-030.
Minimum
10 ft.
10 ft.
10 ft.
10 ft. landscaped
Freeway
landscaped
landscaped
landscaped
setback from the
Frontage Setback
setback from the
setback from the
setback from the
street property
street property
street property
street property
line.
line.
line.
line.
BUILDING STANDARDS
Maximum
2 stories and 30
2 stories and 30
2 stories and 30
2 stories and 30
Building Height
ft.
ft.
ft. for standard
ft.
and Number of
roof.
Stories, except for
uses having a
2 stories and 35
"Public Suffix" (P)
ft. for roofs
designations
having a pitch
greater than
3/12.
Maximum Height
See RMC 4-4-
See RMC 4-4-
See RMC 4-4-
See RMC 4-4-
for Wireless
140G.
140G.
140G.
140G.
Communication
Facilities
Page 3 of 5
ORDINANCE NO. 5132
Exhibit A
RC R-1
R-4 R-8
BUILDING STANDARDS (Continued)
Maximum
Lots 5 acres or
35%.
Lots greater
Lots 5,000 sq. ft.
Building
more: 2%. An
than 5,000 sq.
or greater: 35%
Coverage
additional 5% of
ft.: 35% or
or 2,500 sq. ft.,
(including primary
the total area
2,500 sq. ft.,
whichever is
and accessory
may be used for
whichever is
greater.
buildings)
agricultural
greater.
buildings.
Lots less than
Lots 10,000 sq.
Lots 5,000 sq.
5,000 sq. ft.:
ft. to 5 acres:
ft. or less: 50%
50%,
15%. On lots
greater than 1
acre, an
additional 5% of
the total area
may be used for
agricultural
buildings.
Lots 10,000 sq.
ft. or less: 35%.
Vertical Faigade
All dwelling units
Modulation
shall provide
vertical fagade
modulation at
least every
twenty
horizontal feet
(20'), including
front, side and
rearfagades
when visible
from a street.
Page 4 of 5
ORDINANCE NO. 5132
Exhibit A
RC I R-1 R-4
R-8
LANDSCAPING
AND OPEN SPACE
Minimum Off-
5 ft. wide irrigated
5 ft. wide irrigated
Site
or drought
or drought
Landscaping
resistant
resistant
Abutting Non-
landscape strip
landscape strip
Arterial Public
provided that if
provided that if
Streets for Plats
there is additional
there is additional
and Short Plants
undeveloped right
undeveloped right
Submitted on or
of way in excess
of way in excess
after November
of 5 ft, this shall
of 5 ft, this shall
10, 2004
also be
also be
landscaped.
landscaped.
Minimum Off-
10 ft. wide
10 ft. wide
Site
irrigated or
irrigated or
Landscaping
drought resistant
drought resistant
Abutting
landscape strip
landscape strip
Principal,
provided that if
provided that if
Minor and
there is additional
there is additional
Collector
undeveloped right
undeveloped right
Arterial Streets
of way in excess
of way in excess
for Plats and
of 10 ft., this shall
of 10 ft., this small
Short Plants
also be
also be
Submitted on or
landscaped,
landscaped,
after November
unless otherwise
unless otherwise
10, 2004
determined by the
determined by
reviewing official
the reviewing
during the
official during the
subdivision
subdivision
process.
process.
Minimum On or
At least two (2)
At least two (2)
Off -Site Street
trees of a City-
trees of a City -
Tree
approved species
approved species
Requirements
with a minimum
with a minimum
for Plats and
caliper of 1 112" per
caliper of 1 1/2"
Short Plants
tree shall be
per tree shall be
Submitted on or
planted in the
planted in the
after November
front yard or
front yard or
10, 2004
planting strip of
planting strip of
every lot prior to
every lot prior to
occupancy.
occupancy.
Page 5 of 5
D
oil
•miq's
OL
Contents
Why Go Native, Make a Plan .......................................
1
Prepare the Site, Pick the Hight Plants ......................
2
Proper Planting is Paramount .....................................
3
Maintenance................................................................
4
Appendices:
Sample Planting Plans ...............................................
4
Planting for Sunny, Dry Conditions ............................
S
Planting for Sunny, !foist Conditions .........................
S
Planting for Shady, Dry Conditions ............................
6
Planting far Shady, Moist Conditions .........................
6
Plant .List —Rees
r
Plant List -Shrubs and Ferns ....................................
8
Plant List—Groundcouers and Perennials ...................
9
Footnote Resources for More Information ...................
9
my go native?
.t's up to all of us to keep our water-
ways clean and healthy. Native plants
bring benefits to Northwest land and
water resources, wildlife and
people --and you can have them in
your own yard!
Well —established native plants control erosion by hold-
ing the soil with their roots. They reduce flooding by
slowing runoff. Trees, shrubs and groundcovers clean
water by filtering out sediment and pollutants before
they reach lakes and streams. Northwest fish and
wildlife depend on native plants for food, shelter, and
cover. Once established, native plants in the right place
require little maintenance.
A naturally —cared for native landscape is healthy for
kids, pets and our environment. Your yard makes a
difference! This brochure, plus a little time, money and
sweat, is all you need to build a great looking native
plant landscape. Footnotes refer to Web sites and other
resources found on the last page.
1. Make a plan
Scan the land. Assess your site conditions to deter-
mine what plants will thrive in your spot. Remember
that planning is easier (and cheaper) than replanting.
Consider light, moisture and soil conditions. Is the site
sunny, shady or some of both? How often is the area
wet? Test your soils by sticking a shovel in the ground.
Is it rocky? Sandy? Mostly clay? Need dynamite?
0
Think about the other features of your site, too. Note
power lines, existing trees, view corridors, and height
restrictions. Leave space for decks, additions or water
features you may want to add in years to come.
If you want to plant beside a stream or wetland, check
with your local jurisdiction about possible permit re-
quirements. If you are using only native plants and hand
tools, permits may not be required.
Where to plant? Put your native plant landscape in the
less —traveled areas of your property to attract more
wildlife. Keep your vegetable garden, perennial beds,
and lawn close to the house (and hose) so they get the
attention they need with fewer hassles.
2. Prepare the site
Take some lawn out. Consider replacing your lawn with
natives where grass grows poorly or is losing the battle
with moss. You'll save time and aggravation and your
yard will look great. Unwanted lawn can be cut into
easily lifted squares with a flat bladed spade or removed
with a rented sod remover. Or compost your lawn in
place by covering grass with heavy
cardboard and a few inches of
wood chips or bark.'
Add other features. Now is also
the time to create mounds, install
wildlife snags, rock piles or ponds2
and remove any pesky invasive
weeds. Weed removal is a challenge; Be sure to look at
other resources to battle your problem weeds'.
3. Pick the right plants for your
spot
This brochure includes a plant list of
popular and common natives, many of
which can adapt to a range of sites. Narrow
your choices to plants that match the
sunlight, moisture and space conditions of
your site. Then pick your favorites.
Each native plant performs a role in its ,
habitat, so use each plant to its best advan- wo
tage. To control erosion on the edge of a
stream, plant red osier dogwood, willows, Oregon ash
and vine maple. To attract hummingbirds, plant red
flowering currant and orange honeysuckle.4 And kids as
well as animals enjoy huckleberries and native blackber-
ries. To attract more wildlife, "layer" plants that grow to
different heights; check out the examples of layering on
page 6.2
Is bigger better? Most important, choose plants that fit
your spot when full-grown. Pruning large plants to fit a
small area is loads of work and could harm your plant's
health. Larger plants may suffer more transplant shock
and higher mortality than small plants, but can survive
deer browsing better and are less likely to be trampled
or weed —whacked.
Start shopping. While native plants are increasingly
available in nurseries, some may be a little harder to
finds Ask the King Conservation District
(206-764-3410 or wwwkingcdorand the Washington
Native Plant Society (206-527-3210 or www.wnpsorg)
about their annual native plant sales. When buying, use
the Latin name to get the plant you want. For example,
asking for mock orange could land you the European
Philadelphus coronarius rather than our Northwest native
mock orange, Philadelphus lewisii. Bring the attached
plant list to help.
4. Proper planting is paramount!
Help your plants put their best root forward.6 Take the
time to plant carefully. Fall or winter is the best time of
year to plant. In most years, a newly installed plant's
survival decreases after March as the weather gets drier
and warmer. Set out your plants, still in their pots, where
you want them and rearrange for the look you like.
Cluster three or more shrubs of the same species for a
natural look. General guidelines for plant spacing are 10-
15 feet apart for trees, 5-10 feet for shrubs and 1-3 feet
apart for groundcovers.
4D Take the plant out of its pot
or burlap to view its root
size. Keep the roots wet.
Dig a saucer -shaped hole 2-3
times the width of the root
mass, and about as deep. Fill
hole with water and let
drain.
Build a mound of soil at the bottom of the hole.
Q Loosen bound roots and gently shake off excess
potting soil (not into the planting hole).
Gently spread the roots evenly over the soil mound.
The roots should not circle in the hole.
A 10 Place the plant so the root flare (where the roots join
the stem) is at the soil surface.
10 Replace soil into the hole so it fills the space between
the roots.
10 Water generously and add more soil to fill the hole up
to the root flare. Create a soil berm around the
planting hole to retain moisture.
Q Mulch!
:2-
Mulch, mulch, mulch! Tree grindings, leaves, wood
chips, shredded bark, grass clippings, compost, and
manure are all common mulches.? Spread mulch at least
a couple of inches deep around your new plants (but
keep the mulch a couple of inches from the plant's
stem) . Use mulch over weed barriers (cardboard or
newspaper) if you're eager to reduce weeding. Weed
barriers are temporary, though; annual additions of
mulch and shading by plants helps control weeds and
creates a healthy landscape in the long run.
Do fence me in. A fence can keep livestock, rodents,
pets or children away from new plants. There are a
variety of plant protectors available to keep your tender
new shrubs from becoming a wildlife snack. Once
established, most plants survive moderate munching.
1. aY�su+auasvvv
5. A little maintenance goes a long way
Mulch helps reduce weeding and watering, but you will still
need to help your new plantings get established.' Water when
dry during the first two growing seasons. Deep, infrequent
watering is best. Let the soil nearly dry out between soakings.
Many native plants will need little or no additional water after
one or two growing seasons, when they develop healthy root
systems. Handpull invasive plants to give your new natives a
chance to grow.3 Once a well -planned native landscape
matures, it will almost care for itself.
Learn more! Visit http://dnr.metroke.gov/topics/yard-and-
garden for links to native plant nurseries, resources and
more. Or call 206-296-6519 and ask for information about
native plant landscaping. If you are planning to restore
habitat along streams or rivers, ask for the Small Habitat
Restoration Program.
Sample planting plans
The following four illustrations are intended to give you a
jumping offpoint to get started naturescaping. Different
conditions make it very difficult to present a planting plan
suitable for every site. Soil alkalinity, elevation, slope and
soil texture can all affect the survival of plants in your
yard. Learn more, experiment and celebrate the successes.
* Suggested native plants list
This list contains some of the more common and readily
available native plants. We left out some notable plants,
but there are plenty here to get you started. Check out our
resource list at the end to learn more.
-2
Sample Planting for Sunny, Dry Conditions
(OG) currant (RC) (SB)
0
dogwood (RD) (LF) rose (NR) groundcover (C)
Sample Planting for Sunny, Moist Conditions
Sample Planting for Shady, Dry Conditions
M #
PLAN VIEW
Vine inaple Sword L Salal
(VM) fern (SF) (S)
SECTION VIEW
?!7 ff. high
1.0 ft. hir'll
Wood sorrel
(oxalis) (WS)
dogwood (RD) huckleberry (EH) (DF) flower (IF)
Sample Planting for Shady, Heist Conditions
Native Plant List —Trees
Common name
Botanical name
Ideal growing conditions
Height Notes
Big leaf maple
(Ater macrophyllum)
Deciduous
.... .........
dry —moist, sun —part shade
100 ft
Bitter cherry
(Prunus emarginata)
Deciduous
dry —moist, sun —part shade
30 ft
Black. cottonwood
. .
(Populus balsamifera)
..... _
Deciduous
moist —wet, sun —part shade
160 ft
Black hawthorn
(Crataegus suksdorfrt)
. .......................................
Deciduous
moist —wet, sun —part shade
...............
30 ft
Cascara
(Rhamnuspurshiana)
... ........
Deciduous
*dry —wet, sun —shade
30 ft
Douglas —fir
(Pseudotsuga menziesii)
..
Evergreen
_ __..............
. ..........
dry —moist, sun —part shade
........... _.
250 ft
Grand fir
(Abies grandis)
Evergreen
dry
Oregon ash
(Fraxinus latifolia)
Deciduous
......... .
moist —wet, sun —part shade
.............. .
70 ft
Pacific crabapple
(Malus fusca)
Deciduous
moist —wet, sun —part shade
40 ft
Pacific willow
(Sala lasiandra)
Deciduous
moist —wet, sun —part shade
40 ft
Red alderdry—wet,W�
(Alnus rubra)
Deciduous
..... _
dry wet, sun part shade
120 ft
Scouler's willow
(Salix scouleriana)
Deciduous
....................
dry —moist, sun —part shade
30 ft
Shore pine
(Pines contorta var. contorta)
Evergreen
dry —wet, sun —part shade
50 ft
Sitka spruce
(Picea sitchensis)
Evergreen
....
moist —wet, sun —part shade
200 ft
Sitka willow
(Salix sitchensis)
Deciduous
moist —wet, sun —part shade
30 ft
Vine maple
(Ater circinatum)
Deciduous
.. ......... .................
*dry —moist, sun —shade
.....................................
25 ft
Western hemlock
(Tsuga heterophylla)
........
Evergreen
moist —wet, part shade —shade
225 ft
Western red cedar
.
(Thuja plicata)
.................
Evergreen
.
moist —wet, part shade —shade
200 ft
Western white pine
(Pinus monticola)
Evergreen
dry —moist, sun —part shade
130 ft
Definitions:
Dry: quick drying well draining soils Sun: more than 6 hours sun Deciduous: drops leaves seasonally
Moist: damp much of year (not standing water) Part shade: 2-6 hours sun *Ifplan ted in full sun, prefers moist
Wet: rarely or never dries out Shade: fewer than 2 hours sun conditions. Dry shade is f ne.
Native Plant List —Shrubs and Ferns
Common
BotanicalIdeal!conditionsHeightNotes
Beaked hazelnut
(Corylus cornuta)
...... ......... ......... .........
Deciduous
dry —moist, sun —shade
20 ft
Deer fern
(Blechnum spicant)
- ...__......
Evergreen
_ .........
moist —wet, part shade —shade
............................
2 ft
Evergreen huckleberry
. . .. .. ........ ............
(Vaccinium ovatum)
Evergreen
.....
*dry —moist, part shade —shade
........ ..
..........
loft
Indian plum ... .. _ .......
(Oemleria cerasiformis)
- _ __.. .
Deciduous
*dry —moist, part shade —shade
........................
15 ft
Lady fern
(Athyrium frlix femina)
Deciduous
moist —wet, sun —shade
4 ft
Mock orange
...._. __. _..._... ........
(Philadelphus lewisii)
__...........
Deciduous
_.. ....
dry —moist, sun —part shade
... .... ...
9 ft
Oceanspray
(Holodiscus discolor)
_
Deciduous
dry —moist, sun —part shade
15 ft
Oregon grape (tall)
(Mahonia aquifolium)
Evergreen
*dry —moist, sun —shade
5 ft spreads easily
Pacific ninebark
(Physocarpus capitatus)
Deciduous
moist —wet, sun —shade
13 ft .......................... .
Pacific wax myrtle (Myrica californica) Evergreen
.. ..............
Red elderberry (Sambucus racemosa) Deciduous
. . .. . ......... .........
Red —flowering currant (Ribes sanguineum)
Red huckleberry (Vaccinium parvifolium)
Red osier dogwood (Cornus sericea)
Rosa species
Salal
Salm anberry
Servicebezry
Snowberry
Sword fern
. ............................
Tbimbleberry
........
(R. nutkana, R. pisocarpa)
(Gaultheria shallon)
(Rubus spectabilis)
... ...........
(Amelanchier alntfolia)
................ ................. .................
(Symphoricarpos albus)
......... ........ .........
(Polystichum munitum)
....................
(Rebus parviflorus)
Deciduous
............
Deciduous
Deciduous
Deciduous
Evergreen
Deciduous
Deciduous
Deciduous
. ......
Evergreen
. ..........
Deciduous
.............
*dry —moist, sun —shade
......__...............
15 ft
*dry —moist, sun —shade
................... .
....... .
15 ft
dry —moist, sun —part shade
6 ft
dry —moist, part shade —shade
..... ......
10 ft
moist —wet, sun —shade
15 ft
........................
dry wet, sun —part shade
*dry —moist, part shade --shade
moist —wet, sun shade
.................
dry —moist, sun shade
dry —wet, sun or part shade
dry -moist, part shade —shade
*dry —moist, sun —shade
......... .........
6 it
spreads easily
5 ft
.. ........._
spreads easily
10 ft
spreads easily
20 ft
5 ft
spreads easily
3ft
8 ft
spreads easily
Definitions:
Dry: quick drying well draining soils Sun: more than 6 hours sun Deciduous: drops leaves seasonally
Moist: damp much of year (not standing water) Part shade: 2-6 hours sun * If planted in full sun, prefers moist
Wet: rarely or never dries out Shade. fewer than 2 hours sun conditions. Dry shade is fine.
Native Plant List—Groundcovers and Perennials
Common name
Botanical name
Ideal growing
conditions Height Notes
Beach strawberry
(Fragaria chiloensis)
Evergreen
dry -moist, sun part shade 6 in spreads easily
Bleedingheart
(Dicentra formosa)
Deciduous
dry -moist, part shade -shade 1.5 ft spreads easily
Camas
(Camassia quamash)
Deciduous
..... ....
*dry -moist, sun part shade 1 ft
Inside -out -flower
(Vancouveria hexandra) .....
Deciduous
......
dry moist part shade --shade 6 in spreads easily
Kiunikinuick
(Arctostaphylos uva-ursz)
Evergreen
dry, sun 6 in spreads easily
Western trillium
(Pillium ovatum)
Deciduous
moist, shade 1 ft
Wood sorrel
(Oxalis oregana)
Deciduous
dry -moist, part shade -shade 6 in spreads easily
Definitions:
Dry: quick drying well
draining soils
Sun: more than 6 hours sun Deciduous: drops leaves seasonally
Moist: damp much of year (not standing water)
Part shade:
2-6 hours sun * If planted in full sun, prefers moist
Wet. rarely or never dries out
Shade: fewer than 2 hours sun conditions. Dry shade is fine.
Footnote Resources for More Information
• WSU Native Plant Guide
http://gaidening.wsu.edu/text/nwnative.htm
All these and more are at:
5. Native Plant Sources:
http://dnr.metrokc,Eov/wlr/gil/,npresrcs.htm
•Where to purchase native plants
1. Shrink your Lawn!
1M1Hdnrmetrokc.gov/wlr1p>Znpnursryhtm
httpmHdnr.metrokr,,O-vLw-l-rY-pi/shrunklawn.htni
"` • Restoration Growers Association —Let the King Conserva-
2. Landscaping for Wildlife in the Pacific Northwest. Russell
tion District find local native plants for you! Contact KCD at
Link. UW Press, Seattle. 1499.
206-296-3410 ext. 129.
3. King County Noxious Weeds:
6. Plant it Right Brochure:
gip;//dnr.metrokc.goy/wlr ds/weeds/index htr�
h�tp: /cru.cahe u.edu/CEPublications/niiscO337/miscO337,T)df
4. Native Plant Information:
7. Soils, Compost & Mulch Information:
• Grow Your Own Native Landscape. Item MISCO273 WSU
• Soils, compost and mulch use
Cooperative Extension. Revised 1999. Order at
h trk /s it
1-800-723-1763.
• Mulch and horticulture myths
• Gardening with Native Plants of the Pacific Northwest
htWlZA?vwwcfrwashingion.edu/research.-m-uI
2"d edition. Arthur R. Kruckeburg. UW Press, Seattle 1996.
8. Natural Yard Care Booklet (includes watering):
• Plants of the Pacific Northwest Coast. Jim Pojar and Andy
I nr.me ok w sRecylso o in
Mackinnon. Lone Pine Publishing, Vancouver, BC. 1994,
r&tl mj=dbooklet.shtmUj
R-1 Cluster Code Amendment Draft November 3, 2004
4-2-11QA DEVELOPMENT STANDARDS FOR SINGLE FAMILY RESIDENTIAL ZONING
DESIGNATIONS
(Primary and Attached Accessory Structures
RC R-1 R-4 R-8
DENSITY (Net Densi in Dwelling Units per Net Acre
Minimum
None
None
None
4 dwelling units
Housing Density
per net acre''2
for proposed short
plats or
subdivisions
Maximum
1 dwelling unit
1 dwelling unit per
4 dwelling units
g dwelling units
2
Housing Density
per 50 net
1 net acre except
per 1 net acre
per 1 net acre
acre
that in designated
Urban Separators,
density of up to-1_
unit per gross
404
acre may be
permitted subject
to conditions in
RMC 4-3-110
Urban Separator
Overlay.
NUMBER OF DWELLING
UNITS PER LOT
Maximum
11 dwelling with
1 dwelling unit
1 dwelling unit
1 dwelling unit
Number perlegal
1 accessory
loe
unit
LOT DIMENSIONS .
Minimum Lot
10 acres
1 acre
8,000 sq. ft. '
4,500 sq. ft. for
Size for lots
48$10,000 sq.
except where
parcels greater
created after
ft. for cluster3
small lot
than 1 acre.
November 10,
development
clusters10 are
2004
allowed, R-8
5,000 sq. ft. for
standards shall
parcels 1 acre or
apply.
less.
Minimum Lot
150 ft. for
75 ft. for interior
70 ft. for interior
50 ft. for interior
Width forlots
interior lots.
lots.
lots. 80 ft. for
lots,
created after
corner lots."''3
November 10,
175 ft. for
85 ft. for corner
except where
60 ft. for corner
2004
corner lots.
lots.
small lot
lots
clustersi° are
allowed, R-8
standards shall
apply.
Minimum Lot
200 ft.
85 ft.
80 ft. except
65 ft.
Depth for lots
where small lot
created after
clustersf0 are
November 10,
allowed, R-8
2004
standards shall
apply.
p s
H:IEDNSP1Title 1VIR-1 Clusterin 1E. 4-2-110 A.revised2-27doe.doc
A.re�sed2 27des.deePI!1ED�'`T�ride POR 1 Gjuster�ga& n 2 y , n n de Last printed 2/8/2005 9:40
AM44;QQQS4-.-Q44441 1,ari i 1� i29- I ,.154"Vage 1 of 5
R-1 Cluster Code Amendment Draft November 3, 2004
RC R-1
R-4 R-8
SETBACKS
Minimum Front
30 ft.
30 ft.
30 ft. except
15 ft. for primary
Yard
where small lot
structure.
clusters10 are
allowed, R-8
20 ft. for attached
standards shall
garages accessed
apply.
from front or side
Unit with Alley
yard street.
Access
Unit with Alley
Garage: The
Access Garage:
front yard set-
The front yard
back of the
set -back of the
primary
primary structure
structure may
may be reduced
be reduced to
to 10 ft. if all
20 ft. if all
parking is
parking is
provided in the
provided in the
rear yard of the lot
rear yard of the
with access from
lot with access
a public right -of -
from a public
way or alley.
right-of-way or
alley. 6
Minimum Side
30 ft.
20 ft.
20 ft. except
15 ft. for the
Yard Along a
where small lot
primary structure
Street
clusters10 are
and 20 ft. for the
allowed, 15 ft. is
attached garages
allowed.
which access
from the front and
side yard along a
street.
Minimum Side
25 ft.
15 ft.
15 combined
5 ft.
Yard
ft. 12, 13 are
allowed with a
minimum of 5 ft.
for any side
yard, except
where small lot
clusters i0 are
allowed, 5 ft.
H:\EDNSP\TitlelV\R-1 Clustering\E. 4-2-110 A.revised2-27doc.doct4:T-D `TSP4T itI. Ar' , Gusle in" ^ 2 11 n
A Q 27R4D e�iae nnn y ri,,.,tefing�L .r 2 110 n .de Last printed 2/8/2005 9.40
AM age 2 of 5
R-1 Cluster Code Amendment Draft November 3, 2004
RC I R-1 I R4 I R-8
SETBACKS" Contin
Minimum Rear 35 ft.
Yard
Clear Vision Area
In no case shall
a structure over
42 in. in height
Intrude into the
20 ft. clear
vision area
defined in RMC
4-11-030.
Minimum
10 ft.
Freeway
landscaped
Frontage Setback
setback from the
street property
line.
BUILDING STANDARDS
Maximum
Building Height
and Number of
Stories, except for
uses having a
"Public Suffix" (P)
designation9
25 ft.
In no case shall
a structure over
42 in. in height
intrude into the
20 ft. clear
vision area
defined in RMC
4-11-030.
10 ft,
landscaped
setback from the
street property
line.
2 stories and 30 2 stories and 30
I ft. ft.
Maximum Height See RMC 4-4-
for Wireless 140G.
Communication
Facilities
See RMC 4-4-
140G.
25 ft.
Where small lot
clusters1D are
allowed, 20 ft.
In no case shall
a structure over
42 in. in height
intrude into the
20 ft. clear
vision area
defined in RMC
4-11-030.
10 ft.
landscaped
setback from the
street property
line.
2 stories and 30
ft, for standard
roof.
2 stories and 35
ft. for roofs
having a pitch
greater than
3/12.
See RMC 4-4-
140G.
20 ft.
In no case shall a
structure over 42
in. in height
intrude into the
20 ft. clear vision
area defined in
RMC 4-11-030.
10 ft. landscaped
setback from the
street property
line.
2 stories and 30
ft.
See RMC 4-4-
140G.
H:IEDNSP1Titie MR-1 ClusterinaT. 4-2-110 A.revised2-27doc.docf4.l.- SP-\Tide AnD�aeteFinO& ^ ' "n
2.7dE) dE)eHAE-D `rcn4;+ie nnn 1 Quster-in 1& n 2 1 1 n n Ae Last printed 2/8/2005 9:40
AM ;;9005 c.nn PM W »nnn 3:25 nage 3 of 5
R-1 Cluster Code Amendment Draft November 3, 2004
RC R-1 R-4 R-8
BUILDING STANDARDS (Continued)
Maximum
Lots 5 acres or
35%.
Lots greater
Lots 5,000 sq. ft.
Building
more: 2%. An
than 5,000 sq.
or greater: 35%
Coverage
additional 5% of
ft.: 35% or
or 2,500 sq. ft.,
(Including primary
the total area
2,500 sq, ft.,
whichever is
and accessory
may be used for
whichever is
greater.
buildings)
agricultural
greater.
buildings.
Lots less than
Lots 5,000 sq
5,000 sq. ft.:
Lots 10,000 sq.
ft. or less: 50 /0
50 /o.
ft. to 5 acres:
15%. On lots
greater than 1
acre, an
additional 5% of
the total area
may be used for
agricultural
buildings.
Lots 10,000 sq.
ft. or less: 35%.
Vertical Fagade
All dwelling units
Modulation
shall provide
vertical facade
modulation at
least every
twenty
horizontal feet
(20'), including
front, side and
rear fagades
when visible
from a street.
H:IEDNSPITitle IV1R-1 Clusterin 1E. 4-2-110 A.revised2-27doc.doc
. Last printed 2/8/2005 9:40
AM' »70GS c.n t ��► ry t 3/2Q04 4 PWage 4 of 5
R-1 Cluster Cade Amendment Draft November 3, 2004
RC R-1 R4 R-8
LANDSCAPING
AND OPEN SPACE
Minimum Off-
5 ft. wide irrigated
5 ft. wide irrigated
Site
or drought
or drought
Landscaping
resistant
resistant
Abutting Non-
landscape strip
landscape strip
Arterial Public
provided that if
provided that if
Streets for Plats
there is additional
there is additional
and Short Plants
undeveloped right
undeveloped right
Submitted on or
of way in excess
of way in excess
after November
of 5 ft, this shall
of 5 ft, this shall
10, 2004
also be
also be
landscaped.
landscaped.
Minimum Off-
10 ft. wide
10 ft. wide
Site
irrigated or
irrigated or
Landscaping
drought resistant
drought resistant
Abutting
landscape strip
landscape strip
Principal,
provided that if
provided that if
Minor and
there is additional
there is additional
Collector
undeveloped right
undeveloped right
Arterial Streets
of way in excess
of way in excess
for Plats and
of 10 ft., this shall
of 10 ft., this shall
Short Plants
also be
also be
Submitted on or
landscaped,
landscaped,
after November
unless otherwise
unless otherwise
10, 2004
determined by the
determined by
reviewing official
the reviewing
during the
official during the
subdivision
subdivision
process.
process.
Minimum On or
At least two (2)
At least two (2)
Off -Site Street
trees of a City-
trees of a City -
Tree
approved species
approved species
Requirements
with a minimum
with a minimum
for Plats and
caliper of 1 %Z' per
caliper of 1 '/z"
Short Plants
tree shall be
per tree shall be
Submitted on or
planted in the
planted in the
after November
front yard or
front yard or
10, 2004
planting strip of
planting strip of
every lot prior to
every lot prior to
occupancy.
occupancy.
H:IEDNSPITitle IV1R-1 Clusterin 1E. 4-2-110 A.revised2-27doc.doc
A..r-e -27c es leeH � SP4 49 PPR-1 GWsteri,..g\ 4 2 ' t-'_"ndeeLast printed 2/8/2005 9:40
AWAPA200 5.nn nrx11/34004 94 PWage 5 of 5
Laureen iVicalay - 4-2-110 DRevised2-3.doc Pa e
4-2-11 OD
To be amended by the following changes
Amended February 1, 2005 in Response to Planning and Development Committee public
comments and In house Staff Review
4-2- I IOD
CONDITIONS ASSOCIATED WITH
DEVELOPMENT STANDARDS TABLE FOR
SINGLE FAMILY RESIDENTIAL ZONING DESIGNATIONS
1. a. Phasing, shadow platting, or land
reserves may be used to satisfy the
minimum density requirements if the
applicant can demonstrate that the current
development would not preclude the
provision of adequate access and
infrastructure to future development and
would allow for the eventual satisfaction of
minimum density requirements through
future development.
b. In the event the applicant can show
that the minimum density cannot be
achieved due to lot configuration, lack of
access, environmental or physical
constraints, minimum density requirements
may be waived by the Reviewing Official.
2. Use -related provisions are not
variable. Use -related provisions that are
not eligible for a variance include:
building size, units per structure/lot, or
densities. Unless bonus size or density
provisions are specifically authorized,
the modification of building size, units
per structure, or densities requires a
legislative change in the code provisions
and/or a Comprehensive Plan
amendment/rezone.
3. Clustering is allowed to meet
objectives such as preserving significant
natural features, providing neighborhood
open space, or facilitating the provision of
sewer service. Within designated urban
separators clustering is required, consistent
with the provision of Section 4-3-110,
Urban Separator Overlay Re lations.
a. .
d. a. The maximum net density
requirement shall not be exceeded
except within Urban Separators a
density bonsus may be gg ted allowing
the total denser to achieve 1 dwelling
unitper oss acre for Rrojects that meet
the followingcriteria.
i. Provision of native vegetation cover
on 65% of the gross land area
including both the area within and
outside the open space corridor with
either existing or new vegetative
cover, and at least one of the
following additional criteria.
a) Enhancement of wetlands is
provided at a ratio of one-half acre
enhanced for one acre delineated
within the Urban Separator pursuant
to Section 4-3-050M 12b.
Evaluation Criteria, and Section 4-3-
050M 12.c. Wetlands Chosen for
Enhancement. Enhancement
proposed for a density bonus may
not also be used for a_mitigation for
other wetland alterations.
h) Legal Non -conforming uses are
removed from the site and/or
brought into conformance with
Renton standards.
c) Natural surface pedestrian and/or
equestrian trails with pjLblic access
H:IEDNSP1Title IV1R-1 Custering14-2-110 Mcvised2-3.doc
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Laureen Nicola5 - 4-2-140 DRevised2-3.doc � � P Pa e 2'
are provided as part of an adopted
trail system or, where there is no
planned trail system, in a
configuration approved by the
Reviewing Official.
In the absence of either wetlands or
legal non -conforming uses on the site,
public access and trails shall be
required to the satisfaction of the
Reviewing Official.
b. The area of individual lots shall not be
less than 10,000 sq. ft.
d. Eaves: Eaves and cornices may
project up to 24" into any required
setback.
5. In order to be considered detached, a
structure must be sited a minimum of 6'
from any residential structure.
6. A front yard setback of less than 20' is
allowed if equal to or greater than the
average of the front yard setback of the
existing, abutting primary structures;
however, in no case shall a minimum
setback of less than 20' be allowed for
garages which access from the front yard
strect(s).
C.
7. For pre-existing legal lots having less
c than the minimum lot width required by this
Section, the following chart shall apply for
determining the required minimum side yard
width along a street:
4. Allowed Projections into Setbacks:
a. Fireplace Structures, Windows:
Fireplace structures, bay or garden
windows, enclosed stair landings,
and similar structures as Zoning
Administrator may project 24" into
any setback; provided, such
projections are:
(i) Limited to 2 per fagade.
(ii) Not wider than 10'.
b. Fences: See RMC 4-4-040.
c. Steps and Decks: Uncovered steps
and decks not exceeding 18" above
the finished grade may project to any
property line. Uncovered steps and
decks having no roof covering and
not exceeding 42" high may be built
within the front yard setback.
WIDTH OF
EXISTING
LEGAL LOT
MINIMUM
SIDE YARD
WIDTH
ALONG A
STREET
RC ZONE
150 feet or less 1 25 ft.
R 1 ZONE
Less than or equal
to 50 ft.
10 ft.
50.1 to 51 ft.
11 ft.
51.1 to 52 ft.
12 ft.
52.1 to 53 ft.
13 ft.
53.1 to 54 ft.
14 ft.
54.1 to 55 ft.
15 ft.
55.1 to 56 ft.
16 ft.
56.1to57ft.
17ft.
57.1 to 58 ft.
18 ft.
58.1 to 59 ft.
19 ft.
59.1ft. and greater
19 ft.
R-4 or R-8
ZONE
Less than or equal
to 50 ft,
10 ft.
50.1 to 52 ft.
11 ft.
52.1 to 54 ft.
12 ft.
54.1 to 56 ft,
13 ft.
56.I to 58 ft.
14 ft.
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Lau —re en Nicola y - 4-2-110"DRevised2-3.—do c
58.1 ft, or geater 1 15 ft.
However, in no case shall a structure
over 42" in height intrude into the 20'
clear vision area defined in RMC 4-11-
030.
8. 1n no case shall building height exceed
the maximum allowed by the Airport
Related Height and Use Restrictions, for
uses located within the Federal Aviation
Administration. Airport Zones
designated under RMC 4-3-020.
9. "Public Suffix" (P) properties are
allowed the following height bonus:
Publicly owned structures shall be
permitted an additional 15' in height
above that otherwise permitted in the
zone if "pitched roofs," as defined
herein, are used for at least 60% or more
of the roof surface of both primary and
accessory structures. In addition, the
height of a publicly owned structure
may be increased as follows, up to a
maximum height of 75' to the highest
point of the building:
a. When abutting a public street, 1
additional foot of height for each
additional 1-1/2' of perimeter
building setback beyond the
minimum street setback required;
and/or
b. When abutting a common property
line, 1 additional foot of height for
each additional 2' of
perimeter building setback beyond
the minimum required along a
common property line.
10. In order to serve as a transition between
the lower density R4 zone and the
higher density .R-8 zone "small lot
clusters" of up to a maximum of 50 lots
shall be allowed within 600 feet of an R-
S zone when at least 30% of the site is
permanently set aside as "significant
open space." Such open space shall be
situated to act as a visual buffer between
small lot clusters and other development
in the zone. The percentage of open
space required may be reduced by the
reviewing official to 20% of the site
when:
a) Public access is provided to open
space,
b) Soft surface trails are provided
within wetland buffers, and
c) Store water ponds are desig ed
to eliminate engineered slopes
requiring fencing and enhanced to
allow passive and/or active
recreation.
11. a) Lot size width and depth may be
reduced by the reviewing official when,
due to lot configuration or access, 4-
dwelling units per net acre cannot be
achieved. The reduction shall be the
minimum needed to allow 4-dwelling
units per net acre and shall be limited to
the following minimum dimensions:
Lot size - 7,200 sq. ft
Lot depth — 70 feet
Lot width - 60 feet
12. When lot size is reduced for the purpose
of achieving maximum density, setbacks
may also be reduced. Setback reductions
shall be limited to the following:
Front — 20 feet.
Side yard along a street --15 feet
primary structure, 20 feet attached
garage with access from the side yard.
Minimum side yard combined setback —
15 feet.
Minintum for one yard — 5 feet.
13. For properties vested with a complete plat
H:IEDNSnTitle IV1R-1 Clustering14-2-110 DRevised2-3.doc
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i Laureen Nicola - 4.2-11a DRevised2-3.doc' Page 4
application prior to Nov. 10, 2004, and for
the Mosier IL Maplewood East and
Anthone, the following standards apply.
Vested plats must be developed within 5
years of preliminary plat approval and/or
annexation.
Maximum Density - 5 dwelling
units per net acre
Minimum Lot Size - 7,200 sq. R
Minimum Lot Width - 60 feet for
interior lots, 70 feet for corner lots
Minimum Lot Depth - 70 feet
Minimum Front Yard - 15 feet for the
primary structure, 20 feet for an
attached or detached garage. For a unit
with alley access garage, the front yard
setback for the primary structure may be
reduced to 10 feet if all parking is
provided in the rear yard of the lot with
access from a public right of way or
alley.
Minimum Side Yard Along a Street - 15
feet
Minimum Side Yard - 5 feet
(Amd. Ord. 4963, 5-13-2002)
H.- EDNSP1Tide IVUt-1 Clustering*2-110 DRevised2-3.doc
151
Lau reen Nicola - Urban Separator Overla 8 Feb-3.doc Pa e 1
Proposed New City of Renton Code Creating an Overlay District
Amendments Responding to 1) Planning and Development Committee and 2)Public
Comment 3) In House Staff Comments 4) Planning Commission recommendation
(Shown in bold)
February 3, 2005
4-3-110 Urban Separator Overlay Regulations
A. Purpose:
The pgWose of this section is to implement the Urban Separators policies in the
Community Design Element of the Comprehensive Plan and the King Coun
Countywide Planning Policies. The intent is to provide physical and visual distinctions
between Renton and adjacent communities define Renton's boundaries and create
contiguous open space corridors within and between urban communities, which
provide environmentalvisual recreational and wildlife benefits. Urban Separators
shall be permanent low -density lands, that protect resources and environmentally
sensitive areas.
B. Applicability:
This section shall applygpply to subdivisions and building permits on lands within designated
Urban Separators as shown in the Urban Separators Map.
C. Urban Separators Maps
D. Administration:
1. Review Process: Annlications subiect to Urban Separator Regulations shall be
processed as a component of the governing land use _process.
2. Authority: The Reviewing Official shall have the authority to approve with
conditions, or denim+ proposals based on the provisions of the Urban Separator
Overlay Regulations.
E. Urban Separator Overlay RegWations
1. ContigKous Qpen Space Corridor Established.
A designated contiguous o ens ace corridor is established as shown on the Urban
Se arators Overla Mqp in Section 4-3-110J.
2. Dedication of Open Space Required.
a. Aimroval of a plat, and/or building permit on an undeveloped legal lot in the
Urban Separator Overlay shall require dedication of 50% of the gross land
area of the parcel or parcels included in the land use action as a non -revocable
open space tract retained by orooerty owner, or dedicated to a homeowners
Be
H:IEDNSP\Title IVUR-I Clustering\Urban Separator Overlay$ Feb-ldoc
Laureen Nicola .: Urban Se arator Overla 8 Feb-3.doc Pa e 2
association or other suitable organization as determined by the Reviewing
Official. Acreage in tracts may include critical areas and/or critical area
buffers.
b. Existing residences existing accessory uses and structures, and existing above
ground utilities Iocated in the tract at the time of designation shall not count
toward the 50% gross land area calculation except for un-fenced stormwater
ponds enhanced per techniques and landscape requirements set forth in the
publication the "Integrated Pond" King County Land and Water Resources
Division.
L. Approval of a buildins permit for an addition of 300 square feet for
primary use structure or 500 square feet for an accessory structure shall
require dedication of a conservation easement, protective easement or tract
and deed restriction pursuant to Section 4-3-050G. Native Growth Protection
Areas, on critical areas and critical area buffers located within the Contiguous
Open Space Corridor.
d. hand dedicated, as open space, shall be located within the mapped Contiguous
Open Space Corridor unless a modification is approved pursuant to Section 4-
3-110B6..
3. Uses Allowed In Contiguous Open Space
a. Passive Recreation with no development of recreation facilities
b. Natural surface pedestrian and equestrian trails
c. Animal husbandry (small, medium and large) provided that fencing is
subject to the conditions in 4-3-1103g,
d. Existing residences and accessory uses and structures
e. Underground utilities (small, medium, and Iarg_e)
f. Access Easements.
fD Utilities easements and emergency service access roads may be located
within Contiguous Open Space Corridors for the limited purpose of
providing service to parcels platted after March 2005, for which there is no
practical alternative way to Rrovide service. Utilities and emergency_
service easements shall be developed with permeable surface treatment.
Private access easements for ingress and egress may be located within
Contiguous Open Space in the limited instance where there is no
altemative access to a pre-existing legal lot, but shall not serve lots platted
after March 2005.
g Fencing or similar structures and/or hedges or similar landscape features on
portions of properties abutting and within the Contiguous Open Space Corridor
shall not create a solid barrier. Where required to protect wetlands pursuant to
Section 4-3-050Mc., fencing shall be the minimum necessary.
-2-
HAMNSI'M le IVIR-1 Clustering\Urban Separator Overlay8 Feb-3.doc
Laureen Nicola - Urban Se arator Overly 8 Feb-3.dac • Page 3
4- Uses in Portions of the Urban Separator Outside the Established Contiguous Open
Space Corridor
a. Uses shall be consistent with Section 4-2-060 and 4-2-070B.,
Residential- I Zone One Dwelling unit per net acre.
b. Development shall be clustered outside the Contiguous Open Space Corridor
mapped in 2-3-110J.
5. Standards Within Entire Urban Se arator
a. Forest/veeetation clearing shall be limited to a maximum of 35% of the gross
acreage of the site except:
(1). The percentage of forest/vegetation coverage may be increased to quaIi
for the density bonus allowed in Section 4-2-11OD.
(2). The Reviewing Official mAy modify the percentage of forest/ve etation
retention if determined necessary to meet the surface water retention/detention
standards of Section 4-3-110 E.7.
b. If the existing cleared area of a site, as of March, 2005 is greater than
35% approval of a plat shall require re -planting of forestive etative
cover .
c. Forest/ye etation cover mLiy include a combination of native vegetation
including conifer, deciduous trees and shrubs sufficient to provide water retention
and erosion control functions as determined qppLopriate by the Reviewing
Official. The Reviewing Official shall determine whether existing vegetation
provides functions to meet forest/vegetation coverage standards, and shall require
additional plantinp if existing vegetation is found to be insufficient.
d Stonnwater management shall comply with the 2005 King County_ Surface
Water Design Manual Conservation Flow Control Area Level 2 flow control
standards
e Private access easements and improvements shall be established at the
minimum standard needed to meet public safety requirements.
f Landscape plans required in Section 4-4-070 shall include retention/re-
planting lans as applicable, consistent with standards and lant lists in Kin
County Department of Natural Resources and Parks Water and Land
Resources Division Publication "Going Native"
6. Modification of Mapped Contiguous Open Space:
The Reviewing Official may modify the open space configuration where:
a. Site specific data confirms that the adapted Contiguous Open Space Corridor
mpp includes more than the required goss area for any parcel,or
b. The applicant can demonstrate a configuration of contiguous open space that
provides better orequal provision of the open sace requirement. At a
minimum, open space shall be connected to another contiguous open space
parcel by a fift foot corridor. Modifications to the Contiguous Open Space
Corridor shall be re -mapped during the City's annual Title IV review_ process.
-3-
H:%EDNSP\Title lVR-1 Clustering\Urban SeparatorOverlayS Feb-lduc
I.Laureert, Nicola - Urban Se arator Overla 8 Feb-3.doc Pa e 4
Proposed De inition
Open space, contiguous, Urban Separator: Land permanently set aside as open
space loeated in recorded tracts. Contiguous open space lands may include critical
areas, such as wetlands and steep slopes, and wetland buffers, as well as stormwater
ponds enhanced per the techniques and landscape requirements set forth in The
Integrated Pond, King County Water and Land Resources Division.
Cross references to Other Sections of City Code
Section 4-4-040 Fences and Hedges
Need to discuss further with development services
Need to reference the Urban Separator Overlay requirements
Section 4-4-130 C Allowable Tree Cutting Activities
Tree cutting and associated use of mechanical equipment is permitted as follows, except
as provided in subsection D2 of this Section, restrictions for Critical Areas, and in
Section 4-3-110 E. 5b. Urban Separator Overlay Reaulations (section text continues)
Do we need to add something in the section referencing the land development permit or
will the standards in the overlay automatically take care of that?
Section 4-6-030 F. Drainage Plan Design Criteria Drafting Standards and Contents
The drainage plan shall be prepared in conformance with the Department's
construction plan drafting standards and contents, the City's Standard
Specifications for Municipal Construction and Standard Detail documents,
and the design criteria, construction materials, practices and standard details
contained in chapters 3, 4, and 5 of the current King County Surface water
design manual; provided that the Department's standards and design criteria
will take precedent and prevail in any interpretation of conflicting
contradictory standards and design criteria, and provided that within_
designated Urban Separators regulated in Section 4-4-110 the 2005 King
County Surface Water Design Manual Conservation Flow Control Area Level
2 flow control standards are required.
-4-
H:IEDNSPITitle IV1R-1 Clustering\Urban Separator Overlay$ Feb-ldoc
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BA1MA & HOLMBERG INC.
C-'Ity of Rrc,,into a
�lanr�in hive. ;icn
TECHNICAL INFORMATION REPORT D; -, �. ; �:• ,:
fo r
Wilson Park
May 5, 2009
1
CIO
x
133'�
SIGNAL
Baima & Holmberg, Inc. Job No. 2687-001.
Prepared For
Robert Wilson
720 South 55th Street
Renton, WA 98055
100 FRONT STREET SOUTH • ISSAQUAH WASHINGTON • 98027-3817 • (425) 392-0250 • (425) 391-3055
TABLE OF CONTENTS
SECTION TITLE
PROJECT OVERVIEW
2 CONDITIONS AND REQUIREMENTS SUMMARY
3 OFFSITE ANALYSIS
4 FLOW CONTROL AND WATER QUALITY FACILITY
ANALYSIS AND DESIGN
5 CONVEYANCE SYSTEM ANALYSIS AND DESIGN
G SPECIAL REPORTS AND STUDIES
7 OTHER PERMITS
8 ESC ANALYSIS AND DESIGN
9 BOND QUANTITIES, FACILITY SUMMARIES, AND
DECLARATION OF COVENANT
10 OPERATIONS AND MAINTENANCE MANUAL
Street Address 720 South 551h Street
King County Tax Parcel No. 312305-9125
Project Overview
This project involves developing a 2.5-acre parcel into 13 single-family lots. The site
currently is occupied with a single residence, lawn and wooded areas. The site is located
about 250' north of South 55'h Street, about 150' east of the east terminus of South 53rd
Place, on the slope overlooking SR 167, about %z mile to the west. The site generally
slopes down to the west at an average slope of approximately 20%, Per the SCS soil
maps, the site is underlain with Alderwood soil, sandy loam over glacial till.
Upstream Tributary Drainage
A portion of the parcel to the east of the site drains onto the site. No problems related to
this runoff was noted.
Level 1 Downstream Drainage Analysis
In general, runoff from the site flows west into lots in the adjacent development,
Geneva Court (A). The majority of these runoff flows apparently collect in the drain
behind an 8'± rockery (B) constructed along the back yards of the west -most lots of said
development or in area drains in the back yards, then flow into the storm system in
South 53rd Place (C & D). This flow collects in a stormwater pond/bioswale facility
located at the intersection of South 53rd Place and Talbot Road South (E), about 750'
downstream from the site. This facility outfalls through an 18" pipe to the west side of
Talbot Road South into a shallow, poorly defined channel flowing west through the
woods (F). The flows pass through a short 12" culvert (H) under a walking path then
disappear into thick woods/brush, continuing to flow west to a wooded wetland area (1)
beyond'/4 mile downstream from the site. This wetland apparently drains to a 10' X 5'±
box culvert crossing under SR-167 (Q), about '/z mile downstream from the site.
A small area of the south part of the site drains southwest across the south property line
of the site into the adjacent parcel to the south (Z). These runoff flows through woods,
collecting in a ditches along South 55'h Street (K)(about 350' downstream from the site)
and/or Talbot Road South (L)( about 800' downstream from the site). Flows into the
ditch along South 55th Street (K) continue west in a 6"-12" rock -lined ditch channel
OVERLAP 15 9.56'
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King County Department of Development and, Environmental Services
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part l ' PROJECT OWNER -AND
PROJECT ENGINEER
Project Owner
Address
im hurt-+ 55nk c;r
Phone
Project 5ngineer
•
Company K
Address/Phone t • L
APP.UCATION -'
)c Subdivison
Short Subdivision
Grading
Commercial
Other
Part 2 PROJECT LOCATION AND
�DESCRIPTlON
Project Name
Wi,LeiPIQ FfV--
Location
Township
Range -5
...J? .....Section 31
U
Part'4 :OTHER R1=ICEEWS ANp PERM]TS '
DIFW HPA
COE 404
DOE Dam Safety
FEMA Floodplain
COE Wetlands
Shoreline Management
Rockery
Structural Vaults
Other
Pert 6 STTE:CHARACTERISTICS'
River Floodplain
Wetlands
Stream Seeps/Springs
Critical Stream Reach High Groundwater Table
Depressions/Swales Groundwater Recharge
Lake Other
Steep Slopes
Part 7. SOILS
Soil Type Slopes Erosion Potential Erosive Velcoties
A Oftwgo �t!j&vr rat ?
Additional Sheets Attached
Part8-. DEVELOPMENT LIMITATIONS
REFERENCE LIMITATIONISITE CONSTRAINT
Ch. 4--wDownstream Analysis L,a E)— )AM J15
Additional Sheets Attached
MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS
DURING CONSTRUCTION AFTER CONSTRUCTION
Sedimentation Facilities ►'stabilize Exposed Surface
Stabilized Construction Entrance Remove and Restore Temporary ESC Facilities
✓Perimeter Runoff Control Clean and Remove All Silt and Debris
✓Clearing and Graing Restrictions !/ Ensure Operation of Permanent Facilities
vCover Practices Flag Limits of SAO and open space
(/Constructian Sequence
preservation areas
Other Other
Part i o '. SURFACE WATER`SYSTEM
Grass Lined
Tank
Infiltration
Method of Analysis
Vr , ±y i `�-
Channel
✓Vault
Depression
.,"Pipe System
Compensation/Mitigati
Energy Dissapator
Flow Dispersal
on of Eliminated Site
Open Channel
Wetland
Waiver
Storage
Dry Pond
Stream
Regional
Wet Pond
Detention
Brief Description of System Operation 51)_& M04DC? 'prriyym
Facility Related Site Limitations
Reference Facility Limitation
"—tast in Place Vault
'✓Retaining Wall
Mockery > 4' High
Structural on Steep Slope
Other
.Part 13 _-SIGNATURE O1= PROFE8SIONAL.,ENGINEER ...:. ,
I or a civil engineer under my supervision my supervision have visited the site. Actual site
conditions as observed were incorporated into this worksheet and the attachments. To the best of
my knowledge the information provided here is accurate.
SECTION 2
CONDITIONS AND REQUIRMENTS SUMMARY
PREAPPLICATION MEETING FOR
WILSON PARK
720 S 55TH ST
CITY OF RENTON
Department of Community and Economic Development
Current Planning Division
PRE09-012
February 26, 2009
Contact Information:
Planner Gerald Wasser Phone: 425.430.7382
Public Works Reviewer Rick Moreno Phone: 425.430.7278
Fire Prevention Reviewer; Dave Pargas Phone: 425.430.7023
Building Department Reviewer: Craig Burnell Phone: 425.430,7290
Please retain this packet throughout the course of your project as a reference.
Consider giving copies of it to any engineers, architects, and contractors who work
on the project. You will need to submit a copy of this packet when you apply for
land use and/or environmental permits.
Pre-screening: When you have the project application ready for submittal, call and
schedule an appointment with the project manager to have it pre-screened before
making all of the required copies.
The pre -application meeting is informal and non -binding. The comments provided
on the proposal are based on the codes and policies in effect at the time of review,
The applicant is cautioned that the development regulations are regularly
amended and the proposal will be formally reviewed cinder the regulations in
effect at the time of project submittal. The information contained in this summary
is subject to modification and/or concurrence by official decision -makers (e.g.,
Hearing Examiner, Planning Director, Development Services Director, Department
of Community and Economic Development Administrator, Public Works
Administrator and City Council).
FIRE & EMERGENCY SERVICES
# DEPARTMENT
�� lO% M E M Q R A N D U M
DATE: February 24, 2009
TO_ Rick Moreno, Plan Reviewer
FROM: David Pargas, Assistant Fire Marshal, Community Risk
Reduction
SUBJECT: PRE-APP 09-012
Wilson Park Project
A review of the plans and material regarding the Vasquez Short Plat has been conducted
and completed. Please review the Renton Fire & Emergency Services Fire Code and
Policy comments and. concerns.
1, FIRE FLOW: Structures up to 3,600 square feet (including garage and basement
areas) shall require a minimum fire flow of 1,000 gallons per minute for two
hours. Structures in excess of 3,600 square feet shall meet a minimum fire flow of
1,500 gallons per minute for two hours. A water availability certificate shall be
required.
2. REQUIRED HYDRANTS: As in accordance with Renton Fire & Emergency
Services Department standards, one (1) hydrant shall be required for structures up
to 3,600 square feet and requiring a minimum fire flow of 1,000 gallons per
minute. For structures over 3,600 square feet and requiring a minimurn fire flow
of 1,500 gallons per minute or more shall require a minimum of two (2) hydrants.
The number of hydrants shall also be based on spacing, which shal l be in
accordance with sound engineering practices. All hydrants servicing the Wilson
Park project shall be equipped with five inch Storz fittings on the main ports.
3. HYDRANT SPACING: Residential spacing requires hydrants to be located no
greater than 300 feet to the front of any structure. 1n this case, the existing
hydrants are located much greater than the 300 feet to the existing structures,
Therefore, a minimum of two (2) new hydrants shall be required in order for the
Wilson Park project to meet the 300 foot spacing.
4. FIRE APPARATUS ACCESS: The minimum fire apparatus road access shall
be no less than 20 feet wide and on a surface capable of sustaining the weight of a
fire apparatus. The turning radius shall be 45 feet to the outside and 25 feet to the
inside.
Rick Moreno, Plan Reviewer
Febniary 24, 2009
Page 2 of 3
At this time, 1 am concerned about the minimum 20 foot access off of South
192"d as a private access. Private accesses are difficult to regulate and to prevent
parking in fire apparatus access roadways that are 20 to 28 feet wide.
If this access cannot be designed as a public street, there are some possible
options that could be considered, but would need to be reviewed and approved by
the Fire Marshal. The options I am proposing as a possibility to mitigate the
access issues are as follows:
A) The�gated access would require it to be the type operated of a radio
frequency and known as a Click To Enter system.
B) The 20 foot road access would require to be naarked on both sides of the
road as "NO PARKING AT ANY TIME ". The siznage would need to be
provided by the developer and maintained by the Home Owners
Association.
C) All of the proposed 16 lots would have to be equipped with a residential
fire sprinkler system. The fire sprinkler systerns would not aide in
mitj3Zating,the steep rade issue.
5. FIRE APPARATUS ACCESS — GRADE: It appears that the access into the
Wilson Park neighborhood may be greater than a 15 percent grade. It is important
to note that we strongly require the grade to be no greater than 15 percent for
Renton Fire & Emergency Services to recommend a project. Using fire sprinkler
systems to mitigate an access to allow for it to be greater than 15 percent is not an
option,
6. FIRE SPRINKLER: Residential fire sprinklers are not applicable to this project
unless used as an option to mitigate insufficient fire flow or an access issue other
than grade.
7. FIRE MITIGATION FEES: Fire mitigation fees shall be $488.00 per unit and
shall be paid prior to final plat recording. Credit would be given for the one home
that has been dedicated to be removed.
RECOMMENDATION:
LADDER/AERIAL ACCESS: Ladder access for a 35 foot ground ladder set at
a 70 degree angle shall be provided on all four sides of any structure two stories
or greater in height.
DP/kc
hAced\planninglcwTent plarm inglpreapps\09-012.jeny'�fire comments pre09-012 wilson park.doc
Rick Moreno, Plan Reviewer
February 24, 2009
Page 3 of 3
c; Jerry Wasser, Associate Planner
hAcedlplanninglcurrent planninglpreapps109-012.jerrylfire comments pre09-012 wiison park.doc
n�R
DEPARTMENT OF COMMUNITY AND
ECONOMIC DEVELOPMENT
MEMO RANDU M
DATE; February 23, 2009
TO: Jerry Wasser 42
FROM: Rick Moreno
SUBJECT: Utility and Transportation Comments for Wilson Park Short Plat
P RE09-012
NOTE, The applicant is cautioned that infonnation contained in this summary is
preliminary and non -binding and may be subject to modification and/or concurrence by
official city decision -makers. Review comments may also need to be revised based on
site planning and other design changes required by City staff or made by the applicant.
We have completed a preliminary review fax the above -referenced development proposal.
The following comments are based on the fare -application submittal made to the City o f
Renton by the applicant.
WATER
1. This site is within the Reuton service area. .However, due to elevation of the site,
Renton ca.nilot provide sufficient sustainable water pressure. It is recommended
that the owner receive a certificate of water availability through Soos G�-cck eater
District. The City will be able to release the service area upon evidence that Soos
Creek can service this parcel. This certificate will be submitted to the City prior to
release of service area.
TRANSPORTATION
1, Street improvements are required including, but not limited to paving, sidewalks,
curb and gutter, storm drainage, street fighting and landscaping along street
frontage.
2. Traffic mitigation fees of $75 per additional daily trip shall be assessed per single
family home at a rate of 9.57 trips per day.
3. All wire utilities shall be installed underground per City of Renton Ordinance,
4. A dedication of roadway to adjacent northern property is required prior to
recording. It appears that Tract A is set up for this application, (See Stoma Utility
issues),
5. ratfr may, xtcltg.situ tiisive evluatan sh.l)! be required for roadway
b. The proposed 32 ft. right-of-way with curb, gutter and sidewalk on one side does
not meet current code. An approved variance is required with this proposal.
PRE 09-012 PRCommenis.doc
7. Dedicated right-of-way, meeting City of Renton Street Standards including curb,
gutter and sidewalk improvements fronting all lots shall be required prior to
recording. Current proposal is not acceptable for lots 6 through 9.
8. Maximum road slopes shall be 15% in all cases. Maximum angle of approach is 8
degrees and maximum angle of departure is 10 degrees.
9. Secondary access roadways are sometimes required as specified by the Fire
Marshall_ Secondary access roadways are also required by the City of Renton
Street Standards (Title 4, Chapter 6, Section 60G). If streets are over 500 feet, but
not over 700 ft, long, dwellings shall either provide a secondary access road or
provide an approved residential fire sprinkler system shall be installed, If streets
are over 700 ft., a secondary access road is required. Any proposed access -gating
system requires approval from the Renton Fire Department.
10. Sidewalk, curb and gutter shall abut S 192"a St with radius curb per City of
Renton standards.
SANITARY SEWER
1. This site is within the City of Renton Sewer area. The owner shall extend an 8-
inch sanitary sewer main within the proposed right -of way from S 55"' St. and
extend to the frontage of each proposed lot. A 15-foot utility easement shall be
required to extend to the easterly boundary of lot 6, or lot 9.
2. All system development fees shall apply based on the size of the water meter
services.
SURFACE WATRER
The project is required to do a drainage analysis and meet the design criteria in
accordance with the 1990 King County Surface Water Design Manual with conservation
flow control criteria or current city standard. The 2005 KCSWDM criteria may be
required subject to submitted calculations by the engineer.
The Surface Water System Development Charge (SDC) is S1,012 per new single-
family residence. This is payable at the time the utility construction permit is
issued_
if the proposed Tract A is dedicated for detention, and a right-of-way dedication
is used to connect to the northern lot, traffic bearing lid(s) will be required to any
proposed stonrr vault.
GENERAL COMMENTS
1. All utility and street improvements will require separate plan submittals prepared
according to City of Renton drafting standards by a licensed Civil Engineer.
2_ If fire sprinkler systems are necessary, then a separate fire sprinkler permit will be
required.
3. Permit application must include an itemized cost of construction estimate for these
improvements.
4. The fee for review and inspection of these improvements is 6% of the first
$150,000 of the estimated construction costs 5% of anything over $150,000 but
less than $300,000, and 4% of anything over $300,000. Half the fee must be paid
upon application.
PRE 09�O12 PRComments.doc
CITY OF RENTON
Planning{Building/Public Works
MEMORANDUM
DATE: February 26, 2009
TO: Pre -Application File No. 09-012
FROM: Gerald Wasser, Associate Planner, (425) 430-7382
SUBJECT: Wilson Park
General, We have completed a preliminary review of the pre -application for the above -referenced
development proposal. The following comments on development and permitting issues are
based on the pre -application submittals made to the City of Renton by the applicant and the
codes in effect on the date of review. The applicant is cautioned that information contained in this
summary may be subject to modification and/or concurrence by official decision -makers (e.g., Hearing
Examiner, Planning Director, Public Works Administrator, Development Services Director and City
Council). Review comments may also need to be revised based on site planning and other design
changes required by City staff or made by the applicant. The applicant is encouraged to review all
applicable sections of the Renton Municipal Code. The Development Regulations are available for
purchase for $50.00 plus tax, from the Finance Division on the first floor of City Hall,
Project Proposal: The subject property is located north of S. 55'h St_ and east of Talbot Rd. S. at
720 S. 55`h St. The proposal is to subdivide a 108,884 sq. ft. (2.5 acre) parcel into 16 lots and one
tract, for future development of detached single-family houses. There is one existing home on the
parcel, which would be removed. The site has three different zoning designations, R-1, R-8, and R-
14, and the applicant is proposing a zone change to R-8 for the entire site. The proposed lots range
from approximately 4,500 sq. ft. to 6,243 sq. ft, in size. The preliminary plat would be accessed via a
50 ft. wide access easement running from S. 55;" St. over a neighboring parcel to the south.
Secondary access would be provided via a 30 ft. ingress, egress, & utility easement over a
neighboring property to the south. The site contains protected slopes and a number of significant
trees.
Zoning/Density Requirements: The subject property encompasses three different zoning
designations. Staff estimates that approximately 75,300 sq. ft. (1.73 ac) are zoned R-8, 31,200 sq. ft
(0.72 ac) are zoned R-1, and 2,384 sq. ft. (0.06 ac) are zoned R-14. These are only approximations.
Density is calculated by first subtracting the area of any access easements and critical areas from the
gross site acreage, and then dividing the number of units by the net acreage. The applicant did not
submit a density worksheet for the proposal. Based on the breakdown of haw much land is located in
each zoning designation, staff has estimated that up to 13 units could be built on the R-8 portion of the
lot, no units could be built on the 0.72 acre portion in the R-1, and no units could be built on the R-14
portion of the lot. The R-8 zone permits a minimum of 4.0 units per acre and a maximum of 8.0 units
per acre. The applicant's submittal is predicated on a rezone of the R-1 and R-14 portions of the site
to R-8 zoning. Note: While the applicant may request a rezone to R-8, staff is not supportive of
this change of zone. The R-1 zone was applied in this general area to aid in the protection of
critical areas. The R-1 zone designation on this property is part of a larger continuous area
which Includes wetlands, steep slopes, landslide areas, and coal mine areas. This rezone
would also require a Comprehensive Plan Amendment from Residential Low Density (RLD) to
Residential Single Family (RSF).
Development Standards: Because the only developable part of the lot is the R-8 portion, unless a
rezone and Comprehensive Plan Amendment are approved, staff has only reviewed compliance with
the development standards for that part of the site.
Wilson Park Pre -Application Meeting
February 26, 2009
Page 2 of 3
The R-8 zone permits one residential unit per lot. Detached accessory structures are permitted at a
maximum number of two per lot at 720 square feet each, or one per lot at 1,000 square feet in size.
No accessory structures are allowed on lots without a primary structure.
Minimum Lot Size, Width and Dooth — The minimum lot size permitted in the R-8 zone is 4,500 square
feet for tots greater than 1 acre in size and 5,000 square feet for lots 1 acre or less in size. A minimum
lot width of 50 feet for interior lots and 60 feet for corner lots, as well as a minimum lot depth of 65 feet,
is also required. The total area of the proposed subdivision is greater than 1 acre, so the minimum rat
size is 4,500 square feet. All of the proposed lots in the R-8 portion of the site would far exceed this
minimum. Note. Since this may be a Hillside Subdivision, lots may be required to be larger
than the minimums prescribed in the zone.
Building Standards — The R-8 zone allows a maximum building coverage of 35% of the lot area or
2,500 square feet, whichever is greater for lots over 5,000 square feet in size, Building height is
restricted to 30 feet and 2-stories. Detached accessory structures must be below a freight of 15 feet
and one-story. The gross floor area must be less than that of the primary structure. Accessory
structures are also included in building lot coverage calculations. Given the proposed lot
configuration, it appears that building standards could be satisfied.
Setbacks — Setbacks are the minimum required distance between the building footprint and the
property line or private access easement. The required setbacks in the R-8 zone are 15 feet in front
for the primary structure and 20 feet in front for the attached garage, 20 feet in the rear, 5 feet for
interior side yards, and 15 feet for side yards along streets (including access easements) for the
primary structure and 20 feet for side yards along streets (including access easements) for attached
garages. Given the proposed lot configuration, it appears that setbacks could be satisfied.
Access/Parking' The site has no street frontage, but has existing access easements to South 55"'
Street and SE 192"a Street, The applicant is proposing to access the project via 50-foot road and
utility easement. Road A would have to be a dedicated public right-of-way. Secondary access is
proposed via a 30-foot ingress, egress, and utility easement, Additionally, the City would require that
the extension of Road A at proposed Lots 8, 9 and 10 be developed to the same standards as the rest
of Road A (including width, sidewalk, curb and gutter) to the northern property line. Subdivisions with
five or more internal lots must provide a public road to serve the new homes, Curb, gutter and
sidewalk improvements would be required. Public rights -of -way must be a minimum of 42 ft. wide.
Reductions in public right -of width and street improvements would require a street modification.
Sidewalks on both sides of the street within the plat and on one side of the southwest access from
South 55th Street would be required.
Each lot must allow for the parking of two vehicles on the property.
Landscaping: The applicant would be required to plant at least two trees of a City approved
species with a minimum caliper of 1 1/2 inches in the front yard or planting strip of each lot of the short
plat and a 5-foot strip along the new right-of-way. The trees and landscaping must be planted prior to
final inspection of the new homes. In addition, the stormwater pond must also be landscaped.
Critical Areas: The site contains two small areas of protected steep slopes. There is also an area
of high landslide hazard on the parcel. A geotechnical report will be required at the time of
submittal for a preliminary plat which should include recommendations by the geotechnical
engineer on location and footings of future homes on the site. Due to the fact that there are
known wetlands in the area, a wetlands study must also be submitted. The wetlands study
must be conducted according to the City of Renton Critical Areas regulations, a copy of which
is included in the packet of information given to the applicant at the pre -application meeting.
Secondary review of the wetlands study, at the applicant's expense, may be required. if
wetlands are found, appropriate buffers and Natural Growth Protection
Easements must be established.
Hillside Subdivisions: Hillside Subdivisions are subdivisions in which the average slope is 20% or
in which any street in the subdivision has grades greater than 15% at any point. RMC 4-7-220
PRE09.032 Wilson Park PP (R-8, 36-lot, accoss,new street, slopcs).doc
Wilson Park Pre -Application Meeting
February 26, 2009
Page 3 of 3
establishes the regulations for Hillside Subdivisions including application requirements, grading
information, street requirements, lot size and erosion control requirements.
Significant Tree Retention: A tree inventory and a tree retention plan shall be provided with the
formal land use application. The tree retention plan must show preservation of at least 30% of
significant trees (6-inches and greater). A tree retention worksheet will also be required at the time of
formal application. The submitted tree plan must indicate how proposed building footprints will be sited
to accommodate preservation of significant trees that will be retained,
Consistency with the Comprehensive Plan: The R-8 portion of the site is located within the
Residential Single Family (RSF) Comprehensive Plan Land Use designation, The following proposed
policy is applicable to the proposal:
Land Use Element
Policy L.U-158. Net development densities should fall within a range of 4.0 to 8.0 dwelling units per
acre in Residential Single Family neighborhoods.
Permit Requirements: Because staff is not supportive of the proposed Comprehensive Plan
Amendment and rezone, the applicant may wish to redesign the project utilizing the R-8 portion
of the site only for residential lots. A redesign of the project would affect permit requirements.
The following permit fees assume that a rezone will not be pursued by the applicant,
To subdivide the parcel, the applicant must make formal submittal for Hearing Examiner
Preliminary Plat Review. A submittal checklist, listing the items that must be included in the
submittal packet to the City, is included in the packet of information given the applicant at the pre -
application meeting. The applicant will be required to install a public information sign on the property
and the City will send out information on the plat to neighboring property owners.
There is a $2,000,00 Tee for preliminary plat review. The plat will also require Environmental Review
with an additional fee of $500.00. The time frame for processing the environmental review and
preliminary plat is approximately 12 weeks to the end of the appeal period.
Once approval is received, the applicant must complete any required improvements, such as sewer
and water stubs, surface water management facilities, fire hydrant and grading. A separate utilities
construction permit is required for these improvements. The applicant must also satisfy any conditions
of the preliminary approval from the Hearing Examiner before the plat can be recorded. The newly
created lots may be sold only after the plat has been recorded. The applicant may submit for building
permit review for the new houses before the plat is recorded, but the City can only issue the building
permits when the plat has been recorded.
A demolition permit would be required for the demolition of the existing house on the subject property.
Fees: In addition to the fees for review of the land -use, construction and building permits, the
following mitigation fees would be required prior to recording of the short plat.
A Parks Mitigation Fee based on $530,76 per new single family residence;
A Transportation Mitigation Fee based on $75.00 per each new average daily
trip attributable to the project; and,
A Fire Mitigation Fee based on $488.00 per new single-family residence.
A handout listing all of the City's Development related fees in attached for your review.
Expiration: Upon preliminary plat approval, the preliminary plat approval is valid for 5 years with a
possible one-year extension.
cc: Jennifer Henning
PREp9-012 Wilson Park PP (R-8, Ib-lot, access,new street, slopes) -doe
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SECTION 3
OFFSITE ANALYSIS
BAIMA & HOLMBERG INC.
LEVEL I DOWNSTREAM DRAINAGE REPORT
for
Wilson Plat
.January 23, 2009
Raima & Holmberg, Inc. Job No. 2687-001
Prepared For
Robert Wilson
720 South 55th Street
Renton, WA 98055
100 FRONT STREET SOUTH • ISSAQUAH WASHINGTON • 98027-3817 • (425) 392-0250 • (425) 391-3055
Street Address 720 South 55th Street
King County Tax Parcel No. 312305-9125
Project Overview
This project involves developing a 2.5-acre parcel into 13 single-family lots. The site
currently is occupied with a single residence, lawn and wooded areas. The site is located
about 250' north of South 55`h Street, about 150' east of the east terminus of South 53rd
Place, on the slope overlooking SR 167, about Yz mile to the west. The site generally
slopes down to the west at an average slope of approximately 20%. Per the SCS soil
maps, the site is underlain with Alderwood soil, sandy loam over glacial till.
Upstream Tributary Drainage
A portion of the parcel to the east of the site drains onto the site. No problems related to
this runoff was noted.
Level 1 Downstream Drainage Analysis
In general, runoff from the site flows west into lots in the adjacent development,
Geneva Court (A). The majority of these runoff flows apparently collect in the drain
behind an 8'f rockery (B) constructed along the back yards of the west -most lots of said
development or in area drains in the back yards, then flow into the storm system in
South 53rd Place (C & D). This flow collects in a stormwater pond/bioswale facility
located at the intersection of South 53rd Place and Talbot Road South (E), about 750'
downstream from the site. This facility outfalls through an 18" pipe to the west side of
Talbot Road South into a shallow, poorly defined channel flowing west through the
woods (F). The flows pass through a short 12" culvert (H) under a walking path then
disappear into thick woods/brush, continuing to flow west to a wooded wetland area (I)
beyond'/4 mile downstream from the site. This wetland apparently drains to a 10' X 5':L
box culvert crossing under SR-167 (Q), about 1/2 mile downstream from the site.
A small area of the south part of the site drains southwest across the south property line
of the site into the adjacent parcel to the south (Z). These runoff flows through woods,
collecting in a ditches along South 551h Street (K)(about 350' downstream from the site)
and/or Talbot Road South (L)( about 800' downstream from the site). Flows into the
ditch along South 55th Street (K) continue west in a 6"-12" rock -lined ditch channel
along the north side of the street, passing through a couple of 12" driveway culverts on
the way to the intersection of South 55th Street and Talbot Road South (M). This ditch is
eroded in areas and shows signs of overtopping and flowing into the street, presumably
during the recent storms that caused widespread flooding in Western Washington.
Flows from this ditch collect in an 18" storm system (M). Flows from the ditch along
Talbot Road South (L) collect in the same storm system, about 850' downstream from
the site. The 18" storm system continues west under Talbot Road South and west along
the north side of South 192"a Street (N) to about 1200' downstream from the site where
it apparently discharges into another shallow roadside ditch (0)(because of heavy
vegetation the pipe outlet was not located). This ditch is poorly defined with flows
drifting west along the road, where they enter Springbrook Creels at about 1800'
downstream from the site (P). Springbrook Creek, with a channel generally about 5'
wide and 3' deep (water depth of about 1') continues west to about '/2 mile downstream
from the site (J) where it enters the aforementioned 10' X 5'± box culvert crossing
under SR-167 (Q). The creek continues plowing west on the west side of SR-167. Other
than the overtopping ditch noted along South 55th Street, there were no apparent
downstream drainage problems. A check of King County drainage complaints on their
IMAP website yielded no reported complaints along this downstream drainage path.
S 4M ST
Vicinity Map
168
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SECTION 4
FLOW CONTROL AND WATER QUALITY FACILITY
ANALYSIS AND DESIGN
BAIMA & HOLMBERG, INC.
100 Front Steet South
ISSAQUAH, WASHINGTON 98027-3817
(425) 392-0250 FAX (425) 391-3055
SHEET NO. OF
CALCULATED 6Y 1 --- DATE
CHECKED BY DATE
SCALE
BAIMA & HOLMBERG, INC.
100 Front Steet South
ISSAQUAH, WASHINGTON 98027-3817
(425) 392-0250 FAX (425) 391-3055
JOB Z (0
SHEET NO. OF
CALCULATED BY f DATE
CHECKED BY DATE
crAI c
Pondcale Worksheef
1 Enter site information in the yellow highlighted cells
2 Verify no error message is displayed
3 Results are displayed in Green Box
ote: pondcalc will not work for negative landcover conversions.
pondcalc does not handle existing El or TG very well.
Disclaimer: This spreadsheet is provided without warranty of any kind. Use this spreadsheet
at your own risk. All facility sizes should be verified using KCRTS software.
Rainfall Region
ST
Scale Factor:
1.00
FC Level:
2
acres
,f 205
TF= till forest, T
{either ST or LA see rainfall regions map}
{ 0.8 - 1.2 see rainfall regions map}
{ 1, 2, or 3 see flow control app map}
type
acres
TF�z
TP
rsh��il+ �I��N�If
y. yyqq
i§
�l
TG
0.8
El
1.7
= till pasture, TG = till grass,
Adjusted Acres Error Messages
converted cover
2.5
0.8
1.7
=1 = effective impervious
Acreage Check: post pre
gross 2.5 2.5
adjusted 2.5 2.5
Existing Conditions 100-yr SBUH Peak (offsite Roadway)
--------------------------------------------------------------------------
******************** S.C.S. TYPE-1A DISTRIBUTION
********* 100-YEAR 24-HOUR STORM **** 3.90" TOTAL PRECIP. *********
----------_----------------------------------------------------------------
DATA PRINT-OUT:
AREA(ACRES) PERVIOUS IMPERVIOUS TC(MINUTES)
A CN A CN
.3 .3 81.0 .0 98.0 20.0
PEAK-Q(CFS) T-PEAK(HRS) VOL(CU-FT)
.14 7.83 2576
Developed Conditions 100-yr SBUH Peak (offsite Roadway)
----------------_--------------------------------_----------------------
******************** S.C.S. TYPE-1A DISTRIBUTION ********************
********* 100-YEAR 24-HOUR STORM **** 3.90" TOTAL PRECIP. *********
DATA PRINT-OUT:
AREA(ACRES) PERVIOUS IMPERVIOUS TC(MINUTES)
A CN A CN
.3 .0 86.0 .3 98.0 2.0
PEAK-Q(CFS) T-PEAK(HRS) VOL(CU-FT)
.41 7.67 4658
J06
BAIMA & HOLMBERG, INC.
100 Front Steet South
ISSAQUAH, WASHINGTON 98027-3817
(425) 392-0250 FAX (425) 391-3055
SHEET NO. OF
CALCULATED BY ❑ATE 41�
CHECKED BY DATE
SCALE
SECTION 5
CONVEYANCE SYSTEM ANALYSIS AND DESIGN
SECTION 6
SPECIAL REPORTS AND STUDIES
Altmann Oliver Associates, LLC
PO Kox 57.4 (..111,11is,ii, 11.198011 0(hcc ( [23) 313-15,0 ELN
January 21, 2009
Steve Beck
4735 NE 4th
Renton, WA 98059
Environnwmal
Planning
Landscape
ArchiiC_C.'Lur
AOA-3796
SUBJECT: Wetland Reconnaissance for Wilson Property (Parcel 312305-9125)
720 So. Se Street, Renton, WA
Dear Steve:
On January 15, 2009 1 conducted a wetland and stream reconnaissance on the
subject property and the adjacent new 50-foot wide access easement utilizing the
methodology outlined in the 1997 Washington State Wetlands Identification and
Delineation Manual. No wetlands or streams were identified on or immediately
adjacent to the properly or the new access easement during the reconnaissance.
The south-central portion of the subject property is currently developed with an
existing single-family residence and associated maintained lawn area_ The
remainder of the property consists of a mostly coniferous forest that generally slopes
moderately down from east to west.
Vegetation on the site included western red cedar (Thuja plicata), Douglas fir
(Pseudotsuga menziesh), big -leaf maple (Acer macrophyllum), hazelnut (Corylus
comuta), Indian plum (Oemleria cerasiformis), snowberry (Symphoricarpos albus),
tall Oregongrape (Mahonia equifolium), Himalayan blackberry (Rubus discolor),
trailing blackberry (Rubus ursinus), sword fern (Polystichum munitum), and English
ivy (Hedera helix). The plant community within the undeveloped new access
easement consisted of a mix of trees and brush including black cottonwood (Populus
trichocarpa), big -leaf maple, Himalayan blackberry, snowberry, sword fern, and
English ivy. No hydrophytic plant communities were observed on the site.
Borings taken throughout the property revealed high chroma non-hydric soils and
there was no observation or evidence of prolonged soil saturation.
Steve Beck
January 21, 2009
Page 2
If you have any questions regarding the reconnaissance, please give me a call.
Sincerely,
ALTMANN OLIVER ASSOCIATES, LLC
John Altmann
Ecologist
LIU & ASSOCIATES, INC.
Geotechnical Engineering Engineering Geology Earth science
February 20, 2009
Mr. Robert Wilson
720 South 551h Street
Renton, WA 98055
Dear Mr. Wilson:
Subject: Geotechnical Engineering Study
Wilson Plat
720 South 551h Street
Renton, Washington
L&A Job No. 9AO06
INTRODUCTION
We have completed a geotechnical engineering study for the site of the subject plat, located at the
above address in Renton, Washington. The general location of the project site is shown on Plate
1 — Vicinity Map. We understand that the proposed development for the site is to plat it into 16
single-family residential lots, with supporting infrastructure. The purpose of this study is to
characterize the subsurface conditions of the site and provide geotechnical recommendations for
grading, slope stabilization, erosion mitigation, surface and ground water drainage control,
foundation design and construction, etc., for the proposed development of the site. Presented in
this report are our findings, conclusions and recommendations.
PROJECT DESCRIPTION
For our use in this study, you provided us with a set of topographic survey and plat plan of the
proposed development for the site. According to this plan, the subject site is an rectangle -shaped
land about 526 feet wide (east -west) by about 207 feet deep (north -south), lying to the north of
South 55th Street. The platted building lots are to be accessed from 55`h Avenue South to the
south side of the site via a new roadway entering the site near its southwest corner and an
existing gravel driveway at about 120 feet west of the southeast corner. These roadway/driveway
19213 Kenlake Place NE - Kenmore, Washington 98028
Phone (425) 483-9134 • Fax (425) 486-2746
February 20, 2009
Wilson Plat
L&A Job No. 9AO06
Page 2
are to connect a paved road running mainly east -west down the middle of the site. kdivi"
'•t t}�a r � �qR! �¢ < :x cu'y !� ".5": a, Y,.. t ,^ ui:"s i� �'S4 ..�� � }�*�_...
is to be located at the northwest corner of the site to store storm runoff collected over
the impervious surfaces of the proposed development. We understand that grading for the
proposed development of the site willUMMyt;
im
. Retaining walls and/or rockery
walls may be required to support or line the cut banks and/or fill embankments along the cast,
west and part of the south boundaries of the site.
SCOPE OF SERVICES
Our scope of services for this study comprises specifically the following:
I Review the geologic and soil conditions at the site based on a published geologic map.
2. Explore the site for subsurface conditions with backhoe test pits to a firm bearing soil
stratum or to the maximum depth (about 12 feet) capable by the backhoe used in
excavating the test pits, whichever occurs first.
3. Perform necessary geotechnical analyses and provide geotechnical recommendations for
grading, slope stabilization, erosion mitigation, surface and ground water drainage
control, design and construction for building foundations and stormwater detention vault,
etc., based on subsurface conditions encountered in the test pits and results of our
geotechnical analyses.
4. Prepare a written report to present our findings, conclusions, and recommendations for
the proposed development of the subject plat site.
SURFACE CONDITIONS
SITE CONDITIONS
LIU & ASSOCIATES, INC.
February 20, 2009
Wilson Plat
L&A Job No. 9AOO6
Page 3
The subject site is situated on a broad, moderate to steep, westerly -declining hillside. It is backed
into undeveloped wooded lands to the north and east, and adjoined by a single-family residence
and undeveloped land to the south and a subdivision to the west. The site generally slopes down
t portions of the site generallyliewesterl at grades from 13 to percent. The '*"`y
within the eastern 100 to 120 feet and the western 150 to 200 feet of the site, while the more
moderate area lies in about the middle third of the site where the building pad and the yard of an
existing residence are located.
The existing residence is accessed from South 55th Street via a long gravel driveway. The
,;.�.
unpaved area around the existing house is covered with lawn grass. The g 4 castem
and western areas of the site is dotted with tall, mature evergreen trees with few mature
deciduous trees mixed in between. The eastern steeper area is covered with thick brush, while
the western steeper area is covered by sporadic brush and dense ivy.
GEOLOGIC SETTING
The Geologicp of the Lake Stevens Quadrangle, Snohomish County, Washington, by James
P. Minard, published by U. S. Geological Survey in 1985, was referenced for the geologic and
soil conditions of the subject site. According to this publication, the surficial soil units at and in
the vicinity of the site are mapped as Kame Terrace (Qit) deposits underlain by Ground Moraine
(Qgt).
The geology of the Puget Sound Lowland has been modified by the advance and retreat of
several glaciers in the past and subsequent deposits and erosion. The latest glacier advanced to
the Puget Sound Lowland is referred to as the Vashon Stade of the Fraser Glaciation, which has
occurred during the later stages of the Pleistocene Epoch and retreated from the region some
14,500 years ago.
LIU & ASSOCIATES, INC.
February 20, 2009
Wilson Plat
L&A Job No. 9AO06
Page 4
The Kame terrace deposits were laid down by ice -marginal streams flowing between higher
ground on one side and an ice margin on the other side during the last glaciation. They consist
mostly of silty sand and gravel to cobble. The Kame terrace deposits also contain lenses and
pods of till and beds of sand, silt and clay locally. The Kame terrace deposits are of moderately -
high to high permeability and can provide good foundation support to structures in their native
undisturbed state.
The ground moraine soil unit, underlying the Kame deposits, is composed of a thin layer of
ablation till over lodgmont till sediments, deposited by Puget glacial lobe of the Vashon Stade of
the Fraser Glaciation. The lodgmont till is generally a compact mixture of unsorted clay, silt,
sand, gravel and cobble, commonly referred to as "hard pan". The ablation till is similar to
lodgmont till, but is much less compact and coherent. The thickness generally varies from 2 to 4
feet for the ablation till deposit, and 5 to 30 feet for the lodgmont till deposit. The lodgmont till
deposit is practically impervious, except local lenses of sand and gravel. It has a compressive
strength comparable to that of low-grade concrete and can stand in steep natural or cut slopes for
a long period. The lodgmont till can provide excellent foundation support with little settlement
expected to structures. The overlying ablation till is generally in a loose to medium -dense state,
and is more compressible and permeable.
SOIL CONDITIONS
Subsurface conditions of the site were explored with seven test pits excavated within the site.
These test pits were excavated on February 4, 2009, with a tract -mounted backhoe to depths from
6.5 to 9.5 feet. The approximate locations of the test pits are shown on Plate 2 - Site and
Exploration Location Plan. The test pits were located with either a tape measure or by visual
reference to existing topographic features in the field and on the topographic survey map, and
their locations should be considered only accurate to the measuring method used.
LIU & ASSOCIATES, INC.
February 20, 2009
Wilson Plat
L&A Job No. 9AO06
Page 5
A geoteehnical engineer from our office was present during subsurface exploration, who
examined the soil and geologic conditions encountered and completed logs of test pits. Soil
samples obtained from each soil unit in the test pits were visually classified in general
accordance with United Soil Classification System, a copy of which is presented on Plate 3.
Detailed descriptions of soils encountered during site exploration are presented in test pit logs on
Plates 4 through 7.
The test pits encountered a layer of loose, organic topsoil, from about 10 to 24 inches thick,
mantling the site. In Test Pits 1 and 2, located in the eastern high ground area, the layer of
topsoil was found underlain by a layer of ablation till of brown, medium -dense, silty, fine to
medium sand with a trace of gravel, from 2.3 to 3.5 feet thick. This ablation till is underlain to
the depths explored by a lodgmont till deposit of brown to brown -gray, dense, silty fine sand,
with some gravel and occasional cobble.
Test Pits 3 and 4, located at the downhill fringe of the moderately -sloped middle section of the
site, encountered a Kame terrace deposit underlying the topsoil. The top 1.7 to 2.0 feet of this
Kame terrace deposit is weathered to a loose to medium -dense state and is composed of brown,
fine to medium sand, locally with some silt and/or gravel. The fresh Kane terrace deposit
underneath is medium -dense to dense, and is composed of brown -gray to light -gray, line to
medium sand with a trace of gravel. This clean sandy deposit should be of high permeability.
Test Pits 5, 6 and 7. Located near at the west end of the site, encountered a weathered and/or
fresh Kame terrace deposit, up to about 9.1 feet thick, underlying the topsoil. The Kame terrace
deposits were found underlain by a lodgmont till deposit in Test Pits 5 and 7 at a depth of 5.0 and
9.0 feet, respectively.
GROUNDWATER CONDITION
LIU & ASSOCIATES, INC.
February 20, 2009
Wilson Plat
L&A Job No. 9AO06
Page 6
Groundwater seepage was not encountered by any of the seven test pits excavated on the subject
plat site. The topsoil, ablation till, and weathered and fresh Kame terrace deposits are loose to
medium -dense, and would allow some storm runoff to seep into the ground. The underlying
dense to weakly -cemented lodgmont till deposit is of extremely low permeability and would
perch stormwater infiltrating into the more permeable surficial soils. The amount of and the
depth to this perched groundwater would fluctuate seasonally, depending on precipitation,
surface runoff, ground vegetation cover, site utilization, and other factors. The perched
groundwater may dry up completely during the dryer summer months and accumulate and rise in
the wet winter months. The test pits excavated in the heart of winter did not encountered any
groundwater. Therefore, it is our opinion that groundwater �"'K. " under the subject
g p 3' g J
plat site �_� :1� should be minimal and minor even in the winter months of the year.
P $�; " " Y
DISCUSSIONS AND RECOMMENDATIONS
GENERAL
Based on the soil conditions encountered by the test pits excavated on the site, it is our opinion
that the site is suitable for the proposed development from the geotechnical engineering
viewpoint, provided that the recommendations in this report are fully implemented and observed
during construction. Due to moisture -sensitive fine-grained soils mantling the site and the local
tuge` tc tt areas within the site, we recommend that grading and foundation construction
work for the proposed development be carried out and completed during the dryer period from
April 1 through October 31. If grading work has to proceed beyond the above dryer period, the
measures for slope stabilization, erosion mitigation, and surface and ground water drainage
control recommended in this report should be in place and operational on a daily basis during
construction.
Surf vial unsuitable soils, including topsoil and loose to medium -dense weathered soils mantling
the site, should be stripped down to the medium -dense to dense, fresh Kame terrace and/or
lodgmont till soils within the building pads of the lots and the roadways. The underlying fresh
LIU & ASSOCIATES, INC.
February 20, 2009
Wilson Plat
L&A Job No. 9AO06
Page 7
Kame terrace and/or lodgmont till soils are of high to moderately -high to high strength and are
capable of providing adequate foundation support to the proposed residential buildings, roadways
and stormwater detention vault. Conventional footing foundations constructed on or into the
above competent basal soils may be used to support the proposed residential building and
stormwater detention vault. Structural fill, if required for site grading, should be placed on
proof -rolled, underlying undisturbed, competent basal soils following the stripping of the
surficial unsuitable soils.
GEOLOGIC HAZARDS AND REMEDIATIN
Landslide Hazard
The medium -dense to dense, fresh Kame terrace and lodgmont till soils underlying the site at
shallow depth are of moderately -high to high shear strength and have good to excellent resistance
against slope failures. Therefore, it is our opinion that the potential for deep-seated landslides to
occur on the site should be minimal, provided the recommendations in this report are fully
implemented and complied with during construction.
Erosion Hazard
The topsoil and loose to medium -dense weathered soils are of low resistance against erosion.
Erosion may occur in the weaker surficial soils over theh4,irdiept areas of the site if they
are devoid of vegetation cover and overly saturated. Progressive erosion can lead to shallow,
skin -type mudflows in the galmf areas of the site. To mitigate such erosion hazard,
vegetation outside of construction limits should be preserved and maintained. Unpaved exposed
ground within the site resulted from construction activities should be re -seeded and re -vegetated
as soon as possible. Concentrated stormwater should not be discharged uncontrolled onto the
ground within the site. Stormwater over impervious surfaces, such as roofs and paved roadways
and driveways, should be captured by underground drain line systems connected to roof
downspouts or by catch basins installed in paved roadways and driveways. Water collected by
these drain line systems should be tightlined to discharge into a storm sewer or a suitable
LIU & ASSOCIATES, INC.
February 20, 2009
Wilson Plat
L&.A .lob No. 9AO06
Page 8
stormwater disposal facility. Areas devoid of vegetation cover should be re -seeded and re -
vegetated as soon as possible, and should be covered with clear plastic sheets until the vegetation
is fully established.
Seismic Hazard and Design Consideration
The Puget Sound region is in an active seismic zone. The subject site is underlain at shallow
depth by medium -dense to dense, fresh Kame terrace and lodgmont till soils of moderately -high
to high shear strength. There is a lack of continuous, extensive, static groundwater table at
shallow depth under the site. The combination of the above makes it rather unlikely for seismic
hazards, such as landslides, liquefaction or soil lateral spreading, to occur on the site during
strong earthquakes. Therefore, the seismic hazard of the site should be minimal. The residential
buildings to be constructed on the site, however, should be designed to withstand seismic forces
induced by strong earthquakes. Based on the soil conditions encountered by the test pits, it is our
opinion that Seismic Use Group I and Site Class D should be used in the seismic design of the
proposed residential buildings in accordance with the 2006 International Building Code (IBC).
SITE PREPARATION AND GENERAL GRADING
Vegetation within construction limits should be cleared and grubbed. Loose surficial soils,
including topsoil and loose weathered soils, should be completely stripped down to the medium -
dense to dense, fresh Kame terrace and/or lodgmont till soils within the building pads of the
proposed residential buildings and roadways. The exposed soils should be compacted to a non -
yielding state with a vibratory compactor and proof -rolled with a piece of heavy earthwork
equipment.
TEMPORARY EROSION CONTROL
The onsite surficial soils contain a high percentage of fines, and are sensitive to moisture and can
be disturbed easily by construction traffic when saturated. A layer of clears, 2-to-4-inch, quarry
LIU & ASSOCIATES, INC.
February 20, 2009
Wilson Plat
L&A Job No. 9AO06
Page 9
spalls should be placed over excavated areas and areas of frequent traffic, such as the entrance to
the site, as required, to protect the subgrade soils from disturbance by construction traffic.
Silt fences should be installed along the downhill sides of construction areas to prevent sediment
from being transported onto adjoining properties or streets by storm runoff. The bottom edge of
silt fences should be folded inward and ballasted with onsite soils. Ditches or interceptor trench
drains should be installed on the uphill sides of construction areas, as required, to intercept and
drain away storm runoff and near -surface groundwater seepage. Water captured by such ditches
or interceptor trench drains should be discharged into onsite detention/settling ponds or nearby
storm inlets. The storm inlets, if into which stormwater is to be to be discharged, should be
covered with a filter sock to prevent sediment from entering the storm sewer system. The filter
socks should be cleaned frequently during construction to prevent clogging, and should be
removed after completion of construction.
EXCAVATION AND FILL SLOPES
Under no circumstance should excavation slopes be steeper than the limits specified by local,
state and federal safety regulations if workers have to perform construction work in excavated
areas. Unsupported temporary cuts greater than 4 feet in height should be no steeper than 1 H:1 V
in topsoil, loose to medium -dense weathered Kame terrace and ablation till soils, no steeper than
3/4H:1 V in medium -dense to dense Kame terrace deposits and may be vertical in lodgment till
soils if the overall depth of excavation is no more than 15 feet. Otherwise, temporary cut in
lodgment till should be no steeper than 1/2H:IV. Unsupported permanent cuts should be no
steeper than 211: I V in topsoil, loose to medium -dense weathered Kame terrace and ablation till
soils, no steeper than 1-3/4H:1V in medium -dense to dense Kame terrace deposits, and no
steeper than 1-1/211:1 V in lodgment till soils.
A 5-foot-wide level bench should be built into temporary or permanent cut slopes to keep the
vertical rise between the benches no more than 15 feet. The soil units into which cut slopes and
LIU & ASSOCIATES, INC.
February 20, 2009
Wilson Plat
L&A Job No, 9A006
Page 10
the stability of the cut slopes are to be made should be verified by a geotechnical engineer during
excavation.
Permanent fill embankments required to support structural or traffic load should be constructed
with compacted structural fill placed over undisturbed, proof -rolled, firm, native, fresh Kame
terrace and/or lodgment till soils after the surficial unsuitable soils are completely stripped.
Permanent fill to be placed over slopes steeper than 15 percent grade should be retained
structurally. The exposed ground exceeding 15 percent grade should be benched with vertical
steps not exceeding 4 feet tall after stripping of surficial unsuitable soils and prior to placing
structural fill. The slope of permanent rill embankments should be no steeper than 214:1 V. Upon
completion, the sloping face of permanent fill embankments should be thoroughly compacted to
a non -yielding state with a hoe -pack.
The above recommended cut and fill slopes are under the assumption that groundwater seepage
would not be encountered during construction. if groundwater is encountered, the cut and fill
earthwork should be immediately halted and the slope stability re-evaluated. The slopes may
have to be flattened and other measures taken to stabilize the slopes. Stormwater should not
allowed to flow uncontrolled over cut and fill slopes. Permanent cut slopes or fill embankments
should be seeded and vegetated as soon as possible for erosion protection and long-term stability,
and should be covered with clear plastic sheets, as required, to protect them from erosion until
the vegetation is fully established.
STRUCTURAL FILL
Structural fill is the fill that supports structural or traffic load. Structural fill should consist of
clean granular soils free of organic, debris and other deleterious substances and with particles not
larger than three inches. Structural fill should have a moisture content within one percent of its
optimum moisture content at the time of placement. The optimum moisture content is the water
LIU & ASSOCIATES, INC.
February 20, 2009
Wilson Plat
L&A Job No. 9AO06
Page 11
content in the soils that enable the soils to be compacted to the highest dry density for a given
compaction effort.
Onsite clean silty sand to gravelly sand soils, meeting the above requirements, may be used as
structural fill. Imported material to be used as structural fill should be clean, free -draining,
granular soils containing no more than 5 percent by weight finer than the No. 200 sieve based on
the fraction of the material passing No. 4 sieve, and should have individual particles not larger
than three inches.
The ground over which structural fill is to be placed should be prepared in accordance with
recommendations in the SITE PREPARATION AND GENERAL GRADING and
EXCAVATION AND FILL SLOPES sections of this report. Structural fill should be placed in
lifts no more than 10 inches thick in its loose state, with each lift compacted to a minimum
percentage of the maximum dry density determined by ASTM D1557 (Modified Proctor Method)
as follows:
Application
Within building pads and under foundations
Roadway/driveway subgrade
Retaining/foundation wall backfill
Utility trench backfill
% of Maximum Da Dmaity
95%
95% for top 3 feet and 90% below
92%
95% for top 4 feet and 90% below
STORMWATER DETENTION VAULT
An underground concrete detention vaultis to be
constructed at the northwest corner of the site to store stormwater collected over impervious
surfaces of the proposed development of the site. Two test pits (Test Pits 5 and 6) were
excavated within the footprint of the proposed vault, and these test pits encountered dense
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lodgment till soils and/or medium -dense to dense fresh Kame terrace deposit at depths about 4.0
to 5.0 feet. The vault may be supported on footings founded on these competent basal soils. An
allowable soil bearing pressure not exceeding 3,500 psf may be used for the design of the vault
footing foundations.
A drain line consisting of perforated, rigid PVC, drain pipe or slotted, corrugated ADS, drain
pipe, at least 6 inches in diameter, should be installed at a few inches below bottom of the
perimeter footings of the vault walls to intercept and drain away groundwater which may flow
towards the vault. The drain line should have sufficient slope (0.5% minimum) to generate flow
by gravity, and water collected in the drain line should be tightlined to discharge into a storm
sewer or a suitable stormwater disposal facility. The vault footing drain line should be
completely embedded in washed gravel wrapped in a layer of non -woven filter fabric, such as
140N by Miraf Inc. or approved equal. A vertical drainage blanket at least 12 inches thick
horizontally, consisting of clean 3/4 to 1-1/2-inch washed gravel or crushed rock, should be
placed against the perimeter vault walls. The remaining backfill should be constructed of
structural fill. Alternatively, a vertical drain mat, such as Miradrain 6000 by Mirafi Inc. or
equivalent, may be placed against the perimeter vault walls as the vertical drainage blanket. The
vertical drainage blanket or drain mat should be hydraulically connected to the drain line at the
base of the vault perimeter walls. Sufficient number of cleanouts at strategic locations should be
installed for periodical cleaning of the vault wall drain line to prevent clogging.
The perimeter walls of the detention vault would also serve as retaining walls to support cut
banks and backfill. The perimeter walls of the vault capped with a lid would be restrained at
their top from horizontal movement and should be designed for at -rest lateral soil pressure. For
the condition that groundwater behind the perimeter vault walls can be fully drained by the drain
line provided at the base of the walls, we recommend an at -rest soil pressure of 50 pcf equivalent
fluid density (EFD) be used for the design of vault perimeter walls. To counter the at -rest soil
pressure, a passive lateral soil pressure of 375 pcf EFD may be used, except that the passive
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pressure within the top 12 inches of the finish subgrade should be ignored. The above passive
pressure assumes the backslope of the walls is level or ascending away from the walls. The at -
rest soil pressure may also be resisted by the friction force between the footings and the subgrade
soils based on a coefficient of friction of 0.55.
If the site grades are such that it is not feasible to completely drain groundwater behind the vault
walls with a gravity drain line system, the hydrostatic pressure on the perimeter vault walls
should also be taken into consideration for the design of the vault perimeter walls. For the
condition that a perimeter drain line has to be placed higher than the footing level, the perimeter
vault walls should be designed for a lateral soils pressure of 50 pcf EFD above the drain line
level and a combined lateral soil and hydrostatic pressure of 80 pcf EFD below the drain line
level. The above lateral pressures on the walls may be countered by a passive soil pressure of
375 pcf EFD above the drain line and 210 pcf EFD below.
The detention vault should also be designed for seismic loading based on a 100-year seismic
event. For seismic design of the detention vault walls, a pseudo static soil pressure diagram of
inverted triangle from the finished ground level to the bottom of the foundations should be used.
Based on the soil conditions in the detention vault area, we recommend the lateral soil pressure at
the top of the triangle be 8H psf for a 100-year seismic event, where H is the height from finish
grade over top of the vault to bottom of footings in feet. A one-third increase in the above
recommended allowable soil bearing pressure may be used when considering the seismic loading
condition.
The above design parameters are unfactored ultimate values. Proper factors of safety should be
applied for the design of the vault walls against sliding and overturning failures.
PAVED ROADWAYS AND DRIVEWAYS
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Performance of roadway and driveway pavement is critically related to the conditions of the
underlying subgrade soils. We recommend that the subgrade soils under the roadways/driveways
be treated and prepared as described in the SITE PREPARATION AND GENERAL
EARTHWORK section of this report. Prior to placing base material, the subgrade soils should
be compacted to a non -yielding state with a vibratory roller compactor and proof -rolled with a
piece of heavy construction equipment, such as a fully -loaded dump truck. Any areas with
excessive flexing or pumping should be over -excavated and re -compacted or replaced with
structural fill or crushed rock placed and compacted in accordance with the recommendations
provided in the STRUCTURAL FILL section of this report.
We recommend that a layer of compacted, 7/8-inch crushed rock base (CRB), be placed for the
roadways/driveways. This crushed rock base should be at least 6 inches for the public roadways
and 4 inches for the private driveways. The crushed rock base should be overlain with a 3-inch
asphalt treated base (ATB) topped by a 2-inch-thick Class B asphalt concrete (AC) surficial
course for public roadways and overlain by a 3-inch-thick Class B asphalt concrete (AC) surficial
course for the private driveways.
BUILDING SETBACK
The purpose of building setback from the top or toe or an overly steep portion of a slope is to
establish a safe buffer such that if a slope failure should occur the stability of the structure can be
maintained and damages to the structure minimized. In general, the greater the setback, the
lower the risk for the structure to sustain damages from a slope failure.
To maintain stability, the residential buildings to be constructed on the site should be sufficiently
setback from the top or toe of slopes of 40% gradient or more. We recommend the buildings be
set back at least 15 feet from top or toe of slopes with grades 40% or more. If footing
foundations are used to support the new residences of future development, the footing
foundations should be embedded at least one foot into the underlying, medium -dense to dense,
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fresh Kame terrace or lodgment till soils. if the buildings are to be constructed on the slopes with
grades 40% or more, the footing foundations should be extended downward to such elevation
that the horizontal distance from the edge of footings to the face of slopes should be at least 15
feet, and that a plane drawn from the edge of footings to the toe of slopes of 40% or more
gradient should be no steeper than 2.5H:1 V.
BUILDING FOUNDATIONS
Conventional footing foundations may be used to support the residential buildings to be
constructed on the site. The footing foundations should be placed on or into the underlying,
medium -dense to dense, fresh Kame terrace or lodgmont soils, or on structural fill placed over
these undisturbed competent basal soils. Water should not be allowed to accumulate in
excavated footing trenches. Disturbed soils in footing trenches should be completely removed
down to undisturbed, competent basal soils and the basal soils should be thoroughly compacted
to a non -yielding state with a vibratory mechanical compactor prior to pouring concrete for the
footings.
If the above recommendations are followed, our recommended design criteria for footing
foundations are as follows:
• The allowable soil bearing pressure for design of footing foundations, including dead and
live loads, should be no greater than 3,000 psf if constructed on or into native,
undisturbed, competent basal soils, and no greater than 2,500 psf if constructed on
structural fill placed over competent basal soils. The footing bearing soils should be
verified by a geotechnical engineer after the footing trenches are excavated and before the
footings poured.
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+ The minimum depth to bottom of perimeter footings below adjacent final exterior grade
should be no less than 18 inches. The minimum depth to bottom of the interior footings
below top of floor slab should be no less than 12 inches.
• The minimum width should be no less than 16 inches for continuous footings, and no less
than 24 inches for individual footings, except those footings supporting light -weight
decks or porches.
A one-third increase in the above recommended allowable soil bearing pressure may be used
when considering short-term, transitory, wind or seismic loads. For footing foundations designed
and constructed per recommendations above, we estimate that the maximum total post -
construction settlement of the buildings should be 3/4 inch or less and the differential settlement
across building width should be 1/2 inch or less.
Lateral loads on the proposed residential buildings may be resisted by the friction force between
the foundations and the subgrade soils or the passive earth pressure acting on the below -grade
portion of the foundations. For the latter, the foundations must be poured "neat" against
undisturbed soils or backfilled with a clean, free -draining, compacted structural fill. We
recommend that an equivalent fluid density (EFD) of 325 pef (pounds per cubic foot) for the
passive earth pressure be used for lateral resistance. The above passive pressure assumes that the
backfill is level or inclines upward away from the foundations for a horizontal distance at least
1.5 times the depth of the foundations below the final grade. A coefficient of friction of 0.55
between the foundations and the subgrade soils may be used. The above soil parameters are
unfactored values, and a proper factor of safety should be used in calculating the resisting forces
against lateral loads on the new garage.
SLAB -ON -GRADE FLOORS
Slab -on -grade floors, if used for the residential buildings to be constructed on the site, should be
placed on firm subgrade soils prepared as outlined in the SITE PREPARATION AND
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GENERAL EARTHWORK and the STRUCTURAL FILL sections of this report. Where
moisture control is critical, the slab -on -grade floors should be placed on a capillary break which
is in turn placed on the compacted subgrade. The capillary break should consist of a minimum
four -inch -thick layer of clean, free -draining, 7/8-inch crushed rock, containing no more than 5
percent by weight passing the No. 4 sieve. A vapor barrier, such as a 6-mil plastic membrane,
may be placed over the capillary break, as required, to keep moisture from migrating upwards.
BASEMENT AND CIP CONCRETE RETAINING WALLS
Building basement walls would be required to support backfill. Cast -in -place concrete walls may
be used to retain fill embankments along the west and part of the south boundaries of the site.
Basement walls restrained horizontally at the top are considered unyielding and should be
designed for a lateral soil pressure under the at -rest condition; while cast -in -place concrete
retaining walls free to move at the top should be designed for active lateral soil pressure. We
recommend that a lateral soil pressure of 55 pcf EFD be used for the design of basement walls
restrained at the top; and 40 pef EFD for retaining walls unrestrained at the top. These lateral
soils pressures are applicable to walls with level backslope. With a backslope rising away from
the walls, an additional pressure of 0.75 pcf per degree of angle of the backslope above
horizontal should be added to the above pressures. To counter the active soil or at -rest pressure,
a passive lateral soil pressure of 300 pcf EFD may be used, except that the passive pressure
within the top 12 inches of the finish subgrade should be ignored. The above passive pressure is
applicable to walls with level backslope. The above lateral soil pressures are under the
assumption that groundwater behind the walls is fully drained. To resist against sliding, the
friction force between the footings and the subgrade soils may be calculated based on a
coefficient of friction of 0.55. The above soil parameters are ultimate values, and proper factors
of safety should be used in the design of the basement and retaining walls against sliding and
overturning failures. Basement walls or retaining walls may be supported on footing foundations
seated on or into the underlying, medium -dense to dense, fresh Kame terrace or lodgment till
soils, with an allowable soil bearing pressure not to exceed 3,000 psf.
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A drain line consisting of perforated, rigid PVC, drain pipe or slotted, corrugated ADS, drain
pipe, at least 4 inches in diameter, should be installed at a few inches below bottom of basement
or retaining walls to intercept and drain away groundwater flowing towards the walls. The drain
lines should have sufficient slope (0.5 percent minimum) to generate flow by gravity, and water
collected in the drain line should be tightlined to discharge into a storm sewer or a suitable
stormwater disposal facility. The drain lines should be completely embedded in washed gravel
wrapped in a layer of non -woven filter fabric, such as 140N by Mirafi Inc. or approved equal. A
vertical drainage blanket at least 12 inches thick, consisting of clean, 3/4 to 1-1/2-inch, washed
gravel or crushed rock, should be placed against the walls. Alternatively, a vertical drain mat,
such as Miradrain 6000 by Mirafi Inc. or equivalent, may be placed against the walls as the
vertical drainage blanket. The vertical drainage blanket or drain mat should be hydraulically
connected to the drain lines at the base of the perimeter walls.
ROCKERY WALLS
General
Rockery walls may be used to line the cut banks along the east boundary of the site. Rockery by
nature is not an engineered retaining wall, such as a reinforced concrete wall. Although a rockery
wall can provide some degree of retention capability, its main function is to serve as a protective
facing to retard weathering and erosion process to the earth bank behind the rockery. To achieve
a satisfactory rockery wall, the earth bank behind the wall must be stable by itself on a long -terra
basis. In addition, the rockery wall should be constructed in a proper way to assure long -terra
stability of the cut bank or fill embankment. The medium -dense to dense, fresh Kame terrace
and/or lodgment till deposit underlying the site at shallow depth is of moderately -high to high
shear strength. It is our opinion that cut banks in these soil deposits will be able to maintain
long-term stability if lined by properly constructed rockery. Our design of rockery walls lining
cut banks in these competent deposits is shown on Plate 8 attached hereto.
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Rockery Material and Construction
Rock material used for rockery construction should be hard, well -cemented, sound, durable and
free of cracks, fissures, joints, air holes and other defects. Construction of rockery walls should
be in compliance with the Standard Rockery Construction Guidelines published by the
Association of the Rockery Contractors.
Subgrade and Keyway Trench Preparation
Construction of the rockery walls should start immediately following completion of cut banks
and keyway trenches. The keyway trenches should be cut into medium -dense to dense, fresh
Kame terrace and/or lodgment till soils capable of rendering an allowable bearing capacity of at
least 3,000 psf. The keyway trenches should be at least 12 inches deep below the finish grade in
front of the rockery wall and should be wide enough such that the heel of the keyway trenches
would be at least 12 inches from the back of the base -course facial stones. Keyway trenches
should be free of loose disturbed soils or standing water and the exposed soils at bottom of
keyway trenches should be compacted to a non -yielding state with a vibratory mechanical
compactor prior to rockery installation.
Groundwater Drainage Control
A drain line should be placed in the keyway trenches behind the base -course facial stones to
collect and drain away groundwater flowing toward the rockery walls. The drain lines should
consist of minimum 6-inch, perforated, rigid, PVC pipes, wrapped in a filter fabric sock. The
bottom of the keyway trench and the drain line should have sufficient slope (0.5 percent
minimum) to generate flow by gravity. Water collected in the drain lines should be tightlined to
discharge into a storm sewer or a suitable stormwater disposal facility.
Facial Stones
Facial stones of the rockery walls should be as nearly rectangular as possible with the long
dimension of the stones placed perpendicular to the wall alignment. Facial stones should be
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stacked tightly against one another to minimize voids between the stones. Excessive openings
between the facial stones should be chinked with smaller rock from behind. The rockery walls
should be constructed such that the facial stones of each successive course would be staggered
over and firmly supported on stones of the previous course. Facial stones of the rockery walls
should be tilted back at an inclination no steeper than 6V:1 H.
Drain Rock Course
A drain rock course, consisting of 2-to-4-inch rock spalls, should be installed between the facial
stones and the cut bank in lifts as each course of the facial stones is completed. The horizontal
thickness of the drain rock course should be at least 12 inches. The purpose of the drain rock
course is to retain soils in place while allowing groundwater to bleed out.
PRECAST CONCRETE BLOCK WALLS
General
Precast concrete block walls may be used to support fill embankments to be constructed along
the west and part of the south boundaries of the site. These walls may be constructed with
commercially available precast concrete blocks, such as by Keystone, Lock Block or Redi Rock.
Loose topsoil and loose to medium -dense weathered soils within the keyway trenches of the
walls should be over -excavated down to medium -dense to dense, fresh Kame terrace and/or
lodgment till soils. The block walls should be constructed with geogrid mesh reinforcement
anchored to the block walls and embedded in the wall backfill. The wall should be founded on a
minimum 4-inch layer, 7/8-inch crushed rock, leveling base, placed over firm undisturbed
bearing soils capable of rendering an allowable bearing capacity of at least 3,000 psf. A vertical
drainage blanket should be placed against the back of the concrete block facing and hydraulically
connected to the drain lines at the base of the walls. The remaining wall backfill behind the
vertical drainage blanket should consist of compacted structural fill consisting of clean granular
soils.
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Design Soil Parameters
We recommend that the precast concrete block walls to be constructed to support fill
embankments be designed for a fully drained condition in accordance with the following soil
perimeters:
Reinforced
Retained
Foundation
Leveling
Soils
Soils
Soils
Rock Base
Unit Weight, r, pef
130
120
135
135
Angle of Internal Friction,
36
33
36
40
O, degrees
Cohesion, c, psf
0
0
0
0
The block walls should be designed for a minimum factor of 1.5 against sliding failure and 1.7
against overturning failure under the static loading condition. The Puget Sound region is in an
active seismic zone and the block walls should also be designed under the seismic loading
condition for a 100-year seismic event. The peak ground acceleration is about 0.3g (g = gravity
force) for such an event in the Puget Sound region. The block walls, however, are built with
interlocking concrete blocks with relatively high flexibility, and the blocks do not move in unison
during earthquakes. Therefore, for design of the block wail under the seismic loading condition,
the ground acceleration may be reduced to 0.2g. The block walls should designed for a factor of
safety of at least 1.15 against sliding and overturning failures under the seismic loading
condition. Heavy equipment or material storage should not be allowed within 10 feet of the
block walls; otherwise, the walls should be designed for 250 psf of uniform load.
Construction of Precast Concrete Block Walls
Vegetation within construction limits of the block walls and its backfill should be cleared and
roots thoroughly grubbed. Unsuitable surficial soils, such as topsoil and loose to medium -dense
weathered sand soils within the block walls and backfill footprint should be stripped down to the
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medium -dense to dense, fresh Kame terrace and/or lodgment till soils. Over -excavation down to
these competent basal soils should be backfilled with structural fill.
The keyway trench for the block walls should be cut into native, undisturbed, medium -dense to
dense, fresh Kame terrace and/or lodgment till soils, capable of rendering an allowable bearing
pressure of at least 3,000 psf. The soils exposed at bottom of the keyway trench should be
compacted to a non -yielding state with a vibratory compactor. A minimum 4-inch layer of 7/8-
inch-minus crushed rock leveling base, compacted to a non -yielding state, should be placed over
firm subgrade soils supporting the block walls. The base -course blocks are to be placed on this
crushed rock base with an embedment at least 10 inches below the adjacent finish grade in front
of the block wall. The precast concrete blocks should be stacked tightly against one another.
A minimum 6-inch perforated, rigid, PVC drain line fitted in a non -woven filter fabric sock
should be laid in the keyway trenches behind the base -course blocks. The bottom of keyway
trenches and the drain line should have sufficient slope (0.5 percent minimum) to generate flow
by gravity. The drain pipes should be tightlined to discharge into a storm sewer or a suitable
stormwater disposal facility. A minimum 10-inch-thick (horizontally) vertical drainage blanket,
constructed of clean 1/4 to 1-1/2-inch washed gravel crushed rock, should be placed against the
back of the block wall facing. The vertical drainage blankets should be hydraulically connected
to the drain lines at the base behind the block walls. The wall backfill behind the vertical
drainage blankets should consist of structural fill. The vertical drainage blanket and structural fill
should be constructed in lifts after each course of blocks is completed.
Each layer of geogrid mesh should be laid on level backfill surface, with one end securely
anchored between two rows of concrete blocks, stretched tight, and the other end staked down
prior to the placement of the next lift of wall backfill. Overlaps of geogrid mesh in the direction
of the wall alignments should be at least 12 inches, overlaps in the direction perpendicular to the
wall alignments should not be allowed.
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DRAINAGE CONTROL
Onsite Stormwater Disposal
The moderately -sloped mid -section and the low-lying western portion of the subject plat site are
underlain by fresh Kame terrace deposit of clean, gravelly, fine to medium sand deposit and
infiltration of stormwater into this soil stratum is feasible for the residential buildings to be
constructed in these areas. The impervious lodgmont till deposit, however, was found underlying
"Tract A", located at the northwest corner of the site, at a depth as less as 5 feet below the
existing grade. Therefore, we do not recommend a concentrated infiltration facility in "Tract A"
to dispose a large amount of stormwater into the ground. This is because the large amount of
concentrated disposed stormwater in this tract may increase the potential of groundwater seepage
downhill off the subject site where the lodgmont till may be exposed or near the ground surface.
Increased groundwater seepage may elevate the possibility of erosion, sloughing and landlside.
Appendix C — Small Project Drainage Requirements, of the Kin County, Washington Surface
Water Design Manual, January 24, 2005, allows stormwater collected on 2,000 or more but not
more than 10,000 square feet of impervious surfaces of small residential projects to be disposed
onsite with infiltration or dispersion method. The "full infiltration" method specified in Section
C.2.2 — Full Infiltration of the above design manual can be used on sites underlain by medium
sand or coarse sand or gravel and cobble. The moderately -sloped mid -section and the low-lying
western portion of the subject plat site are underlain by fresh Kame terrace deposit of clean
gravelly, fine to medium sand deposit and are qualified for using Full Infiltration method to
dispose stormwater for the residential buildings in these areas.
According to the above design manual, infiltration trenches installed into clean gravelly sand
soils should be designed to be at least 30 feet long for every 1000 s.f. of impervious surface
served (with a 2-foot-wide trench). The length of infiltration trenches may be shortened
proportionally with increased trench width.
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The infiltration trenches should be set back at least 10 feet from adjacent buildings and 5 feet
from property lines. The schematic presentation of an infiltration trench with a single dispersion
pipe to serve the residential buildings is shown on Plate 9. The infiltration trenches should be at
least 24 inches wide. The bottom of infiltration trenches should be excavated at least 6 inches
into the underlying clean, fresh, gravelly sand Kame terrace deposit. The side walls of the
trenches should be lined with a layer of non -woven filter fabric. The trench is then filled with
clean 3/4 to 1-1/2-inch washed gravel or crushed rock to within about 8 inches of the finish
grade. The' dispersion pipes should be constructed of 4-inch rigid or 6-inch flexible perforated
PVC pipes and laid level in the gravel or crushed rock filled trenches at about 16 inches below
the top of trenches. The top of the gravel or crushed rock fill should also be covered with the
filter fabric liner. The remaining trench should then be filled with compacted on -site soils.
Stormwater captured over impervious surfaces should be routed into a sediment control
structure/oil-water separator structure before being released into the infiltration trenches.
Building Footprint Excavation
Building footprint excavation for the proposed residential buildings, if encountering groundwater
seepage, should have the bottom of excavation sloped and ditches excavated along bases of the
cut banks to direct collected groundwater into sump pits from which water can be pumped out.
A layer of 2-inch crushed rock should be placed over footing bearing subgrade soils, as required,
to protect the soils from disturbance by construction traffic. This crushed rock base should be
built to a few inches above groundwater level, but not less than 6 inches thick. The crush rock
base should be compacted in 12-inch lifts to a non -yielding state with a vibratory mechanical
compactor.
Runoff over Impervious Surfaces
Storm runoff over impervious surfaces, such as roofs and paved roadways/driveways, should be
collected by underground drain line systems connected to downspouts and by catch basins
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installed in paved roadways/driveways. Stormwater thus collected should be tightlined to
discharge into a storm sewer or suitable stormwater disposal facilities.
Building Footing Drains
A subdrain should be installed, around the perimeter footings of each of the residential buildings.
The subdrains should consist of a 4-inch-minimum-diameter, perforated, rigid, drain pipe, laid a
few inches below bottom of the perimeter footings of the buildings. The trenches and the drain
lines should have a sufficient gradient (0.5% minimum) to generate flow by gravity. The drain
lines should be wrapped in a non -woven filter fabric sock and completely enclosed in clean
washed gravel. The remaining trenches may be backfilled with clean onsite soils. Water
collected by the perimeter footing subdrain systems should be tightlined, separately from the roof
and surface stormwater drain lines, to discharge into a storm sewer or suitable stormwater
disposal facility.
Surface Drainage
Water should not be allowed to stand in any areas where footings, on -grade slabs, or pavement is
to be constructed. Finish ground surface should be graded to direct surface runoff away from the
residential buildings. We recommend the finish ground be sloped at a gradient of 3 percent
minimum for a distance of at least 10 feet away from the buildings, except in the areas to be
paved.
Cleanouts
Sufficient number of cleanouts at strategic locations should be provided for underground drain
lines. The underground drain lines should be cleaned and maintained periodically to prevent
clogging.
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RISK EVALUATION STATEMENT
The subject site is underlain at shallow depth by medium -dense to dense Kame terrace and/or
lodgmont till soils. These soils are of moderately -high to high shear strength and gutaer
was not Jenctiun a etl . iy the test ;fits excav to ;vn lthe site r Therefore, the bite should be quite
stable. The key to maintain site stability during and after completion of construction is to have
proper and adequate erosion and drainage controls. It is our judgment that provided the
recommendations in this report are fully implemented and observed during construction, the
areas disturbed by construction will be stabilized and will not increase the potential for soil
movement. In our opinion, the risk of damage to the proposed development and from the
development to adjacent properties due to soil instability should be minimal.
LIMITATIONS
This report has been prepared for the specific application to this project for the exclusive use by
Mr: kabert wilson `kid his associates, consultants and contractors. We recommend that this
report, in its entirety, be included in the project contract documents for the information of the
prospective contractors for their estimating and bidding purposes and for compliance with the
recommendations in this report during construction. The conclusions and interpretations in this
report, however, should not be construed as a warranty of the subsurface conditions. The scope
of this study does not include services related to construction safety precautions and our
recommendations are not intended to direct the contractor's methods, techniques, sequences or
procedures, except as specifically described in this report for design considerations.
Our recommendations and conclusions are based on the geologic and soil conditions encountered
in the test pits, and our experience and engineering judgment. The conclusions and
recommendations are professional opinions derived in a manner consistent with the level of care
and skill ordinarily exercised by other members of the profession currently practicing under
similar conditions in this area. No warranty, expressed or implied, is made.
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The actual subsurface conditions of the site may vary from those encountered by the test pits
excavated on the site. The nature and extent of such variations may not become evident until
construction starts. If variations appear then, we should be retained to re-evaluate the
recommendations of this report, and to verify or modify them in writing prior to proceeding
further with the construction of the proposed development of the site.
CLOSURE
We are pleased to be of service to you on this project. Please feel free to call us if you have any
questions regarding this report or need further consultation.
Nine plates attached
Yours very truly,
LIU & ASSOCIATES, INC.
J. S. (Julian) Liu, Ph.D., P.E.
Consulting Geotechnical Engineer
LIU & ASSOCIATES, INC.
SECTION 7
OTHER PERMITS
SECTION 8
ESC ANALYSIS AND DESIGN
SECTION 9
BOND QUANTITIES, FACILITY SUMMARIES, AND
DECLARATION OF COVENANT
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
STORMWATER FACILITY SUMMARY SHEET
Development Date
Location
ENGINEER
DEVELOPER
Name
Name
Firm
Firm
Address
Address
Phone
Phone
Developed Site: Acres Number of lots
Number of detention facilities on site: Number of infiltration facilities on site:
ponds ponds
vaults vaults
tanks tanks
Flow control provided in regional facility (give location)
No flow control required Exemption number
Downstream Drainage Basins
Immediate Major Basin
Basin A
Basin B
Basin C
Basin D.
Number & type of water quality facilities on site:
biofiltration Swale (regular/wet/ or
continuous inflow?)
combined detention.1WQ pond
(WQ portion basic or large?)
combined detention/wetvault
compost filter
filter strip
flow dispersion
farm management plan
landscape management plan
oil/water separator (baffle or coalescing plate?)
catch basin inserts: Manufacturer
pre -settling pond
pre -settling structure: Manufacturer
flow-splitter catchbasin
sand filter (basic or large?)
sand filter, linear (basic or large?)
sand filter vault (basic or large?)
stormwater wetland
wetpond (basic or large?.)
wetvault
DESIGN INFORMATION
INDIVIDUAL BASIN
A
B
C
D
Water Quality design flow
-Water_Quality treated volume or wet and Vr
1998 Surface Water Design Manual 91119'
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
DESIGN
INFORMATION, cont'd
TOTAL
INDIVIDUAL. BASIN
Drainage basin(s)
Onsite area
A
B
C
D
Offsite area
Type of Storage Facility
Live Storage Volume
Predenj ed Runoff Rate
2-year
10- ear
100- ear
Developed runoff rate
2-year
I0- ear
100 ear
T e of restrictor
Size of orificelrestriction
No. 1
No. 2
No. 3
No. 4
FLOW CONTROL & WATER QUALITY FACILITY SUMMARY SHEET SKETCH
All detention, infiltration and water quality facilities must include a sketch per the following criteria:
Heading for the drawings should be located at the top of the sketch (top right-hand corner).
The heading should contain:
• North arrow (point up or to left) * D9#
• Plat name or short plat number • Address (nearest)
• Date drawn (or updated) • Thomas Brothers page, grid number
2. Label CBs and MHs with the plan and profile designation. Label the control structure in writing or abbreviate
with C_S. Indicate which structures provide spill control.
3. Pipes --indicate:
Pipe size
Pipe length
Flow direction
Use s single heavyweight line
4. Tanks-- use a double, heavyweight line and indicate size (diameter)
5. Access roads
• Outline the limits of the road
• Fill the outline with dots if the road is gravel. Label in writing if another surface.
6. Other Standard Symbols:
* Bollards: 0 0 0 0 is tr Q a
• Rip rap 000000
000000
Fences --x--- x---x---x--- x--- x---
• Ditches—D---}D----D--}D
7. Label trash racks in writing.
S. Label all streets with the actual street sign designation. If you don't know the actual street name, consult the plat
map.
9. Include easements and lot lines or tract limits when possible.
10. Arrange all the labeling or writing to read from left to right or from bottom to top with reference to a properly
oriented heading.
11. Indicate driveways or features that may impact access, maintenance or replacement.
911199 1998 Surface Water Design Manual
2
SECTION 10
OPERATIONS AND MAINTENANCE MANUAL
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