Current through Register Vol. 24-18, September 15, 2024
(1) Construction plans and specifications
must be clear and detailed documents and in an electronic format acceptable to
the department.
(2) Plans must
include the following:
(a) Design flow,
treatment level, drainfield and tank sizing, and hydraulic loading
rate;
(b) LOSS schematic or flow
diagram;
(c) Hydraulic profile of
the LOSS; and
(d) Plan and profile
views as applicable of all LOSS components.
(3) Plan sets must be scaled to clearly show
all necessary information and include the following:
(a) A title sheet, plan and profile sheets,
and other information that outlines and details the LOSS facilities design:
(i) Title block indicating the project title,
owner's name, date, seal and signature of the design engineer;
(ii) Index to individual sheets;
(iii) Vicinity map with project site
location;
(iv) Master site plan
showing facilities served and general system layout; and
(v) List of abbreviations, definitions, and
symbols used within the plans.
(b) A general statement that all work must be
in conformance with the requirements of this chapter and other design and
technical standards specified by the design engineer.
(4) Plan sheets must be consecutively
numbered and include, as appropriate:
(a) A
north arrow;
(b) Description of
scale in text and with a graphical bar;
(c) A descriptive title and date;
(d) Plan views;
(e) Section views;
(f) Profile views;
(g) Elevations;
(h) Easement and franchise locations and
boundaries;
(i) Component
details;
(j) General layout;
and
(k) Supplemental
views.
(5) Sewage tanks
and other treatment component plans and specifications must:
(a) Show location, dimensions, and elevations
of all treatment and pumping units;
(b) Include detailed plan and cross-section
views with dimensions;
(c) Include
installation details including placement depth and bedding materials, and
connections to the tank to minimize settling impacts;
(d) Include a detailed standard plan,
including any related electrical components, and installation requirements for
tanks designed for individual lots;
(e) Specify tank capacity, baffling, filters,
risers and other appurtenances, liquid volume, emergency, scum and sludge
volumes, float switch or other control component settings;
(f) Identify manufacturer and model for
prefabricated tanks; and
(g)
Include a statement that:
(i) Any
substitutions must be approved by the design engineer; and
(ii) All prefabricated tanks must meet the
requirements of chapter 246-272C WAC.
(6) Plans and specifications must include
design and structural calculations and all necessary construction information
for tanks constructed on-site.
(7)
Plans and specifications for collection and transmission piping must specify:
(a) Pipe type, material and size;
(b) Pipe elevations;
(c) Depth from grade and slope if
applicable;
(d) Installation
details including placement depth and bedding materials;
(e) Location and detail for all cleanouts and
other appurtenances;
(f) Horizontal
setbacks from all other utility piping; and
(g) All water-sewer crossing detail and
instructions.
(8) Plans
for the drainfield component must:
(a) Use an
appropriate scale of 1:50 or less;
(b) Show plan view of trenches or beds in
relation to site topography, showing contours on maximum two-foot
intervals;
(c) Show trench or bed:
(i) Length;
(ii) Separations;
(iii) Pipe size, materials, and
configuration; and
(iv) Detail of
orifice size, spacing and orientation.
(d) Show locations of numbered test pits and
test wells, if any, in relation to primary and reserve drainfields;
and
(e) Show trench or bed profile
with width, depth, piping, cover and any features such as sand, gravel,
geotextile, chambers.
(9) Plans for alarm systems must:
(a) Show location of panels and alarms;
and
(b) Identify manufacturer and
model number of panel.
(10) Plans for flow metering must show:
(a) Valve locations;
(b) Access boxes to grade; and
(c) Any special installation
instructions.
(11) Plans
must show all electrical components and include a statement that all components
meet applicable state or federal codes.
(12) Plan notes must include quality
assurance, inspection, and testing:
(a) Where
appropriate, the installer shall provide documentation to the design engineer
that sand or other media meets specifications;
(b) The design engineer or authorized
representative shall inspect the work during construction;
(c) The design engineer shall schedule a
final inspection and drainfield pressure test witnessed by the department prior
to cover; and
(d) The installer
shall call for a special inspection for the following type of work:
(i) Poured-in-place septic tanks and pump
chambers and other special containment vessels;
(ii) Proprietary treatment or distribution
components;
(iii) Any special
excavation requirements;
(iv)
Placement of select fill material or final elevation of fill;
(v) Testing of the pressure distribution
network prior to final inspection;
(vi) Pressure testing of all piping;
and
(vii) Water tightness testing
of all tanks.
(13) All LOSS construction specifications
must be in conformance with state or nationally recognized standards. Examples
include, American Public Works Association standards, Ten States Standards,
Department of Ecology's Criteria for Sewage Works Design, Department of
Transportation's Standard Specifications for Road, Bridge, and Municipal
Construction, and the department's recommended standards and
guidance.
(14) Specifications must
include all construction information not shown on the plans and necessary to
inform the installer of the design requirements including, but not limited to:
(a) The quality of materials;
(b) Workmanship and fabrication of the
project;
(c) Type, size, strength,
operating characteristics, and rating of equipment;
(d) Allowable leakage for testing gravity
sewer pipe;
(e) Electrical
apparatus and wiring components;
(f) Meters;
(g) Operating tools;
(h) Construction materials;
(i) Special filter or drainfield media other
than native soil;
(j) Other
appurtenances;
(k) Instructions for
testing materials and equipment as needed to meet design standards;
and
(l) LOSS component and process
testing to confirm functionality prior to department final
inspection.
Statutory Authority:
RCW
70.118B.020. 11-12-035, §
246-272B-04400, filed 5/25/11, effective
7/1/11.
