Section 24.17.130 Soil and site evaluation.

24.17.130 Soil and site evaluation.

(1) Only professional engineers, designers, or the health officer may perform soil and site evaluations. Soil scientists may only perform soil evaluations.

(2) The person evaluating the soil and site shall:

(a) Report:

(i) A sufficient number of soil logs to evaluate conditions within:

(A) The initial disposal component; and

(B) The reserve area;

(ii) The ground water conditions, the date of the observation, and the probable maximum height;

(iii) The topography of the proposed initial system, the reserve area, and those areas immediately adjacent that contain characteristics impacting the design;

(iv) The drainage characteristics of the proposed initial system, the reserve area and those areas immediately adjacent that contain characteristics impacting the design:

(A) The existence of structurally deficient soils subject to major wind or water erosion events such as slide zones and dunes;

(B) The existence of designated flood plains and other areas identified in the local management plan required in Section 24.17.060; and

(I) Wells and suction lines;

(II) Water sources and supply lines;

(III) Surface water and stormwater infiltration areas;

(IV) Abandoned wells;

(V) Outcrops of bedrock and restrictive layers;

(VI) Buildings;

(VII) Property lines and lines of easement;

(VIII) Interceptors such as footing drains, curtain drains and drainage ditches;

(IX) Cuts, banks, and fills;

(X) Driveways and parking areas;

(XI) Existing OSSs; and

(XII) Underground utilities;

(b) Use the soil and site evaluation procedures and terminology in accordance with Chapter 5 of the On-Site Wastewater Treatment Systems Manual, EPA 625/R-00/008, February 2002, or later version except where modified by, or in conflict with, this chapter;

(c) Use the soil names and particle size limits of the United States Department of Agriculture Natural Resources Conservation Service classification system;

(d) Determine texture, structure, compaction and other soil characteristics that affect the treatment and water movement potential of the soil by using normal field and/or laboratory procedures such as particle size analysis; and

(e) Classify the soil as in Table V—Soil Type Descriptions:

Table V—Soil Type Descriptions
Soil Type	Soil Textural Classifications
1	Gravelly and very gravelly coarse sands, all extremely gravelly soils excluding soil types 5 and 6, all soil types with greater than or equal to 90% rock fragments.
2	Coarse sands.
3	Medium sands, loamy coarse sands, loamy medium sands.
4	Fine sands, loamy fine sands, sandy loams, loams.
5	Very fine sands, loamy very fine sands; or silt loams, sandy clay loams, clay loams and silty clay loams with a moderate or strong structure (excluding platy structure).
6	Other silt loams, sandy clay loams, clay loams, silty clay loams.
7 Unsuitable for treatment or dispersal	Sandy clay, clay, silty clay, strongly cemented or firm soils, soil with a moderate or strong platy structure, any soil with a massive structure, any soil with appreciable amounts of expanding clays.

(3) The owner of the property or his agent shall:

(a) Prepare the soil log excavation to:

(i) Allow examination of the soil profile in its original position by:

(A) Excavating pits of sufficient dimensions to enable observation of soil characteristics by visual and tactile means to a depth three (3) feet deeper than the anticipated bottom of the disposal component; or

(B) Stopping at a shallower depth if a water table or restrictive layer is encountered; and

(ii) Allow determination of the soil’s texture, structure, color, bulk density or compaction, water absorption capabilities or permeability, and elevation of the highest seasonal water table; and

(b) Assume responsibility for constructing and maintaining the soil log excavation in a manner to reduce potential for physical injury as required by Chapter 296-155 WAC.

(i) Place excavated soil no closer than two (2) feet of the excavation;

(ii) Provide an earth ramp or steps for safe egress to a depth of four (4) feet, then scoop out a portion from the floor to gain the additional two (2) foot depth necessary to observe the six (6) feet of soil face; however, the scooped portion is not to be entered;

(iii) Provide a physical warning barrier around the excavation’s perimeter; and

(iv) Fill the excavation after the health officer has approved or denied the application.

(4) The health officer:

(a) Shall render a decision on the height of the water table within twelve (12) months of receiving the application under precipitation conditions typical for the region;

(b) May require water table measurements to be recorded during the wet season, if insufficient information is available to determine the highest seasonal water table;

(d) May reduce the required number of soil logs for the OSS serving a single-family residence if adequate soils information has previously been developed.

(5) Per RS&Gs, winter evaluations may be necessary when there is evidence of a seasonal water table within eighteen (18) inches of grade or when there is seasonal surface water within less than seventy-five (75) feet, although these parameters may be reduced at the discretion of CCPH staff depending on the type of system proposed and the characteristics of the soil and site. If CCPH staff determine that a winter evaluation is necessary, the applicant must file a request between October 1st and December 31st in order to obtain a decision by the following year.

(a) CCPH will issue a decision by June 1st of the following year, provided precipitation conditions have been typical for the region and provide sufficient information upon which CCPH can issue a decision.

(b) Planned cut-off drains must be clearly indicated in the application and constructed by the time of application submittal. (Sec. 14 of Ord. 2007-10-01; amended by Sec. 10 of Ord. 2021-11-05)