CITY OF WEST RICHLAND – Building Division
3801 W Van Giesen, West Richland WA 99353
Ph: (509) 967-5902 Fx: (509) 967-2419
Inspection Request Line 967-3518
Retaining Wall
Permit Submittal Requirements
PERMIT REQUIRED:
A permits is required for Retaining Walls made of any material
(concrete, masonry, ecology block, steel, railroad ties, etc.),
unless specifically exempted as described in this handout.
PERMIT EXEMPT:
Retaining Walls four feet in height or less measured vertically
from the finished grade at the exposed toe of the wall to the
highest point unless: supporting a surcharge or, impounding,
Class I, II, II-A liquids or, subject to the provisions of Chapter
???
CODE:
International Building Code 2006 Edition WSDOT/APWA
Standard Specifications for Road, Bridge, & Municipal
Construction (Current Edition)
FEE:
Fee is based on valuation of the project plus a 25% plan review
fee and a $4.50 state fee.
SUBMITTAL REQUIREMENTS:
1. A Critical Areas Determination, issued by the Planning Division
2. Permit Application
3. Soils Investigation or Soils Report – Two (2) copies, stamped and signed by a
Washington State licensed Geotechnical Engineer or Engineering Geologist.
4. Grading Plan – Two (2) copies, with yardage calculations
5. Plot Plan – Two (2) copies, scaled 1”=20’
6. Retaining Wall Section and Elevation Views – Two (2) copies, stamped and signed by a
Washington State licensed Engineer.
7. Retaining Wall Design Calculations, - Two (2) copies, stamped and signed by a Washing
State licensed Engineer
8. Erosion and Sedimentation Control Plan – (2) copies
9. For Retaining Walls in Critical Areas designated as geologically hazardous areas or, in
the mapped ESLHA, a letter from a Washington State licensed Geotechnical Engineer
addressing the criteria of WRMC ??????
INTRODUCTION
Retaining Walls, including shoring structures, are structural systems that provide lateral
support for vertical or near-vertical slopes of soil. Several common types of Retaining Walls
include: gravity, semigravity, cantilever, soldier pile, sheet pile, proprietary modular block,
mechanically stabilized earth, and soil nail retaining walls. The City of West Richland does
not consider rockeries (walls constructed of rock from the earth) to be Retaining Walls.
DEFINITIONS
Wall Height. For permitting purposes, Retaining Wall height is defined as the height
measured vertically from the finished grade at the exposed toe of the Retaining Wall to the
highest point of the finished wall.
Setback Area Height. For setback purposes, Retaining Wall Setback Area Height is
defined as the height measured vertically from the original grade to the highest point of the
Retaining Wall supporting soil.
EXEMPTIONS FROM PERMIT REQUIREMENTS
A Retaining Wall permit is not required for the following conditions: however retaining
walls must also meet the General Requirements listed within this handout:
 Retaining Walls four (4) feet or less in height, provided that none of the conditions
below (numbers 1-5 under General permit requirements) apply. (See Wall Height
definition above.)
 For Retaining Walls proposed for construction in conjunction with an approved
subdivision or short plat, a separate retaining wall permit is not required. However,
wall details shall be included on the subdivision/short plat civil drawings, the
submittal requirements listed on page 1 of this handout shall be submitted with the
plans, and plan approval signed by the City Engineer will constitute Retaining Wall
approval. Retaining Walls shall be designed, reviewed and approved based on the
requirements of this handout.
 Retaining Walls four (4) feet or less in height proposed on an individual lot with a
Critical Areas determination of Erosion Hazard Area only. Other Critical Areas
determinations do not apply to this exemption.
GENERAL PERMIT REQUIREMENTS
A Retaining Wall permit shall be required when any of the following conditions apply:
1. Retaining Walls greater than four (4) feet in height to eight (8) feet in height, (see
Wall Height definition above.)
 Plans must be designed and stamped by a WA State licensed Engineer
 Design Calculations shall be submitted with the plans, stamped by the
Engineer of record
 Peer review and special inspection are not required for Retaining Walls 8 feet
or less in height unless a special environmental or potentially hazardous
conditions exists
2. Retaining Walls greater than eight (8) feet in height, (see Wall Height definition
above.)
 Plans must be designed and stamped by a WA State licensed Engineer
 Design calculations shall be submitted with the plans, stamped by the
Engineer of record
 Peer review and special inspection are required
3. Retaining Walls of any height located in a designated Critical Area other than
Erosion Hazard area.
 Plans must be designed and stamped by a WA State licensed Engineer and
comply with WRMC Chapter ????
 Design calculations shall be submitted with the plans, stamped by the
Engineer of record
 Peer review and special inspection are required for all Retaining Walls
located in designated Geologically Hazardous Critical Areas
4. Retaining Walls of any height supporting a surcharge from a street, road, alley,
driveway, parking, building, structure or other surcharge or Retaining Walls that
impound flammable liquids or hazardous materials.
 Plans must be designed and stamped by a WA State licensed Engineer
 Design calculations shall be submitted with the plans stamped by the
Engineer or record
 Peer review and special inspections are required for Retaining Walls grater
than 6 feet in height
5. Terraced Retaining Walls are subject to the noted conditions above for permit
requirements and exemptions; the following conditions also apply:
 Each tier is considered to be a separate Retaining Wall (if any individual tier
exceeds the threshold for a permit then a permit shall be required for the
entire terraced structure)
 The upper tier shall be setback from the lower tier a distance equal to, or
greater than, the height of the lower Retaining Wall tier.
 If the distance between the upper tier and the lower tier is less than the height
of the lower tier then the lower tier shall be considered to support a surcharge
from the upper tier and a permit shall be required and be subject to the
requirements of this handout
RETAINING WALL CONSTRUCTION
For gravity block and modular block retaining walls, the contractor shall follow the
manufacturer’s recommended installation procedure. For all other types of retaining walls,
the contractor shall follow the plans and specifications prepared by the Engineer of Record.
Keyway
The Engineer of Record shall determine the minimum embedment for all walls in accordance
with the manufacturer’s recommendations or as required by the International Building Code.
Wall Backfill
For gravity and modular block retaining walls, the backfill material shall be placed in lifts to
an elevation approximately six (6) inches below the top of each course of blocks, until the
uppermost course is placed. Any backfill material on the bearing surface of one block course
shall be removed before setting the next course. For all other types of retaining walls, the
contractor shall follow the approved plans and specifications prepared by the Engineer of
Record.
Backfilling
When fill is placed behind a Retaining Wall, the soil parameters for design are based on the
knowledge of the proposed fill soils and the anticipated control of the compaction. Special
inspection by a licensed geotechnical engineer is required to verify that the soils and
compaction procedures are proper and the compacted soils properties achieve the design
parameters.
Underdrain
A minimum six (6) inch diameter rigid perforated or slotted drainpipe shall be placed in a
shallow excavated trench located along the backside of the Retaining Wall. The pipe shall be
placed on the surrounded by “Gravel Backfill for Drains” to a minimum height of 1’-6”
above the bottom of the pipe. A filter fabric shall surround the gravel backfill and shall have
a minimum 1’-0” overlap along the top surface of the gravel. This requirement for fabric
may be waived by the Engineer of Record if soils and water conditions make it unnecessary.
The perforated drainpipe shall be connected to the storm drainage system (other than
detention) or an approved outfall.
Terraced Retaining Walls
Each tier of the terraced Retaining Wall shall be installed in accordance with the prescriptive
installation design standards described herein and reflected in the diagrams on the project
specific plans and specifications prepared by the Engineer of Record. For gravity block and
modular block retaining wall installed in accordance with the prescriptive design standards
described herein, the upper Retaining Wall tier shall not be located within a horizontal
distance from the lower Retaining Wall tier equal to the height of the lower Retaining Wall.
DESIGN CRITERIA FOR RETAINING WALLS
General
There are two types of Retaining Walls; one type is protecting, typically used for soils that are capable of
standing by themselves without support and the other type is retaining or supporting, for soils that are not
capable of standing or remaining at the existing slope.
Retaining Walls shall be designed based on standard engineering methods provided by the International
Building Code (current adopted edition) and WSDOT/APWA Standard specifications for Road, Bridge, and
Municipal Construction (current edition). Width and height of footings and walls shall be provided, including a
reinforcing steel schedule and design calculations. The submitted plans, specifications, engineering
calculations, diagrams soils report, and other data shall conform to the requirements of the current adopted
edition of the International Building Code but not be limited to, the requirements of IBC Chapter 1806.
Gravity block and modular block walls shall meet the requirements of the City Engineering installation design
standards described herein and reflected in the attached diagrams. All other types of Retaining Walls not
described within this document shall conform to the requirements of the International Building Code.
Wall Backfill
For gravity and modular block retaining walls, the
material located directly behind the wall shall conform to
the manufacturer’s recommendations or plans and
specifications prepared by the Engineer of Record. If there
is no manufacturer’s recommendation or plans and
specifications prepared by the engineer of record, the wall
backfill shall consist of well draining granular material in
conformance with WSDOT/APWA 9-03.12(2)
Sieve Size
4” Square
2” Square
US No. 4
US No. 200
Dust Ratio:
% Passing US No. 200
% Passing US No. 40
Sand Equivalent
Gravel Backfill for Drains
Sieve Size
A system shall be designed to intercept ground water
behind the retaining wall in order to prevent hydrostatic 1” Square
pressure on the wall. The intercepted groundwater shall be ¾” Square
channeled to an approved drainage system. Specify all
3/8” Square
drainage materials (piping, type of backfill, etc.) on the
US No.4
drainage plan. Note, the backfill that surrounds the drainage
pipe shall conform to WSDOT/APWA 9-03.12(4) outlined in US No. 200
the adjacent chart. This material shall be placed to a twelve
(12”) inch minimum width between the entire block facing and the cut slope.
Percent Passing
100
75-100
22-66
5.0 max
52 min.
Percent Passing
100
80
100
10
40
0
4
0
2
GENERAL REQUIREMENTS
1. All Retaining Wall designs that require a permit shall have plans and details stamped
and signed by a WA State Licensed Professional Engineer, including the design
calculations when required.
2. A soils investigation/report is required to determine the classification of soil design
parameters and soil design bearing capacity. All report recommendations shall be
incorporated into the Retaining Wall design including drainage considerations.
3. Retaining Walls shall not exceed there (3) feet in height, above original grade, when
located in setback areas. (See Setback Area Height definition above)
4. Retaining Walls of any height shall not be constructed over public utility easements,
or be constructed to adversely affect drainage, or create a sight distance hazard.
5. The slope behind the top of a Retaining Wall shall be no steeper than 2:1
(horizontal:vertical) unless specifically approved by the applicant’s Geotechnical
Engineer.
6. Retaining Walls of any height shall not be constructed in, on, or over (developed or
undeveloped) City right-of-way, unless specifically approved by the City Engineer.
Per WRMC Chapter ??? approval of an Encroachment Permit may be granted to
locate a Retaining Wall within the City right-of-way if it does not interfere with the
public’s use of the right-of-way and/or if the proposal benefits the public interest,
safety or convenience.
7. A two (2) foot minimum shy distance shall be maintained from Retaining Walls to
the edge of roads (including private access roads serving 3 or more lots), streets and
alleys.
8. Temporary Spoil. Unless substantiated by the applicant’s Geotechnical Engineer,
temporary spoil or stockpiling shall be placed no closer than two (2) feet from the
surface edge of the excavating, measured from the nearest base of the spoil to the
cut. Spoil should be placed so that it channels rainwater and other run-off water
away from the excavation. Permanent spoils are considered to be fill and are subject
to IBC permitting and fill requirements (a separate fill/grading permit may be
required.
9. General Requirements apply even if a retaining wall is exempt from permitting
requirements.
GENERAL INSPECTION REQUIREMENTS
1. If the Retaining Wall is located on private property and is permitted as part of a
building permit or as a separate Retaining Wall permit, the property owner is
responsible to call the City Building Inspection line (509-967-3518) for the
following inspections, including but not limited to:
 Location and Setbacks
 Verification of Bearing Soil
 Placement of Reinforcement
 Wall Drainage (behind wall and to a point one foot away from wall)
 Drainage dispersal inspection (inspected by City Engineer for drainage on
foot away from wall to approved dispersal area)
 Final Inspection and Height
2.
If the Retaining Wall is constructed as part of a subdivision or short plat site
improvement, the property owner is responsible to call the City Engineer at 509967-5434 for the noted inspections above.
SPECIAL INSPECTION REQUIREMENTS
 For poured concrete Retaining Walls, if the design Engineer specifies a concrete
design strength greater than 2500psi, a special inspection is required by either the
Engineer of Record or a Special Inspector approved by the Building Official who is
certified by the Washington Association of Building Officials (WABO) for reinforced
concrete.
 The Geotechnical Engineer of record shall verify conformance with the project
specific Retaining Wall design including but not limited to: soil bearing conditions
and capacity, groundwater conditions, verification of backfill material, compaction
methods, drainage, and retaining wall placement procedures, etc.
 Field reports by the Geotechnical Engineer of record shall be submitted in a timely
manner to the Building Division for review and approval for private individual lot
development and to the Engineering Division for subdivision/short plat and right-ofway development.
PERMIT SUBMITTAL REQUIREMENTS
1. CRITICAL AREAS CHECKLIST
A Critical Areas Determination, issued by the Planning Division, must be completed and on
file with the City. Provide applicable information as indicated by the decision for
compliance with WRMC Chapter ???.
2. SOILS INVESTIGATION OR SOILS REPORT
The classification of soil and design bearing capacity must be determined based on
observation and tests of the soil materials disclosed by borings or excavations. Such work
shall be performed by a Washington State Licensed Professional Geotechnical Engineer or
Engineering Geologist. Soils investigation/report recommendations shall be incorporated
into the Retaining Wall design and shall conform to the requirements of IBC 1802 and IBC
Table 1804.2
3. GRADING PLAN Three (3) copies, scaled 1”=20’.
When fill or grading for Retaining Walls exceeds 50 cubic yards, a separate grading plan
with yardage calculations must be submitted (additional permit fees required). Exception:
Grading in designated Critical Areas or within the mapped ESLHA requires grading plans,
peer review and additional permit fees regardless of the amount of grading or fill.
4.
PLOT PLAN Three (3) copies, scaled 1”=20’.
a) North arrow, property line dimensions, streets, alleys, driveways, parking areas, etc.
b) Clearly show edge of City right-of-way, curb, gutter, sidewalk, street trees, etc.
c) Detail public and private access and utility easements that encumber the property
*Provide copies, of all recorded easements that affect the property
d) Show location of existing house, garage, decks, etc. on the subject property
e) Show location of streams, creeks, drainage courses, etc. on the subject property
f) Clearly show the proposed location of the Retaining Wall and distance to property
lines
g) Indicate the height of the wall, including top and bottom elevations of the wall at
five (5) foot linear intervals to clearly show height of the wall along its entire length
h) Clearly show how wall drain pipe will connect or discharge to an approved drainage
system
i) Show existing and proposed grade contours at two (2) foot linear intervals for slopes
up to 15% and five (5) foot linear intervals for slopes exceeding 15% slope
5.
SECTION AND ELEVATION VIEWS Two (2) copies, stamped and signed by a
Washington State licensed Engineer with the following:
a) Provide a typical section view of the Retaining Wall.
b) Footing and wall detail: specify width, maximum height, reinforcing steel schedule,
rebar spacing, etc.
c) Wall detail: specify width, height, steel schedule, etc.
d) Drainage provisions behind wall (piping size and material) and backfill proposed.
Clearly show how Retaining Wall drain pipe will connect or discharge to an
approved drainage system.
6. RETAINING WALL DESIGN CALCULATIONS Two (2) copies, stamped and
signed by a WA State licensed Professional Engineer and shall include: soils classification,
unit weight of soil, allowable bearing pressure, active and passive earth pressures,
liquefaction potential, coefficient of friction, seismic loads, site specific surcharge loads,
water table information, grading calculations, global slope stability, sliding resistance,
overturning, local capacity of walls (bending, shear, deflection, embedment), lagging design
and fascia design. For manufactured systems (i.e., block walls, keystone) and other
engineered Retaining Wall systems provide the installation instructions with the permit
application submittal.
7. EROSION AND SEDIMENTATION CONTROL PLAN
Erosion and Sedimentation Control Plans per WRMC Chapter ????.
Three (3) copies of
8. LETTER
FROM
GEOTECHNICAL
ENGINEER
SPECIFICALLY
ADDRESSING THE CRITERIA OF WRMC CHAPTER ???.
For Retaining Walls in designated geologically hazardous Critical Areas or in the mapped
ESLHA, the Geotechnical Engineer of record shall submit a stamped and signed letter
acknowledging that the criteria of WRMC Chapter ??? has been reviewed and all applicable
design considerations for code compliance have been incorporated into the plans.
NOTE: THE PURPOSE OF THIS HANDOUT IS TO ASSIST THE PUBLIC IN COMPLYING WITH DETAILED PERMIT
SUBMITTAL REQUIREMENTS. IT IS NOT A COMPLETE LIST OF PERMIT OR CODE REQUIREMENTS AND SHOULD NOT
BE USED AS A SUBSTITUTE FOR APPLICABLE LAWS AND REGULATIONS. IT IS THE RESPONSIBILITY OF THE
OWNER/DESIGN PROFESSAL TO REVIEW THE SUBMITTAL FOR COMPLETENESS AND APPLICABILITY TO OTHER
CODES. ONLY COMPLETE APPLICATIONS WILL BE ACCEPTED BY THE CITY FOR REVIEW.