Soil log and site evaluation
Test pits, profile description, water table and restrictive layer depth, and a determination of what the parcel can support.
Pierce County
Septic Design and Site Evaluation in Pierce County, WA
Before a system can be permitted, someone has to establish what the ground will accept. In Pierce County, where soils change over short distances, this step decides more about the final cost than any other.
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Tell us what you need
Your request goes to an on-site sewage professional certified by the Tacoma-Pierce County Health Department and serving Pierce County, not a national lead list.
The request form is not accepting submissions yet. This site is new and the intake line is still being set up. Until it is live, nothing is collected here, because a form that renders but delivers nowhere is worse than no form at all.
Prefer to talk? Call (253) 367-7679.
What it is
Septic Design and Site Evaluation, explained
A site evaluation logs the soil profile, depth to any restrictive layer, depth to the water table, slope, and the setbacks that apply to the parcel from wells, structures, boundaries and surface water.
A designer then produces the system drawing the Health Department reviews. On straightforward ground the design is routine; on difficult ground it is engineering.
The output is a document. Everything after it, permit, installation, inspection, follows from what the evaluation found.
Pierce County specifics
Why this works differently in Pierce County
The Puget lobe and Mount Rainier between them gave Pierce County outwash, till, lahar sediment and near-surface bedrock, sometimes within a couple of miles of each other. Regional rules of thumb are unreliable here in a way they are not in flatter, more uniform counties.
Parcels on the Graham and Roy prairies often log fast-draining gravel and support conventional designs. Parcels on the Gig Harbor peninsula and the Bonney Lake plateau frequently log till and do not.
Valley parcels in Puyallup, Sumner and Orting log fine sediment with a shallow water table, which restricts depth and often forces a mound or pressure design.
Variants
Types and approaches
New system design
A full design for an unbuilt parcel or a replacement, drawn to the standard the Health Department reviews against.
Repair design
A design for replacing a failed component or absorption area on an existing system, working within what the parcel still has available.
Pre-purchase feasibility
An evaluation before buying undeveloped land, establishing whether the parcel can carry a system at all and roughly what type.
How it runs
The process, in order
- Records review. Existing permits and as-builts for the parcel are pulled before anyone digs.
- Test pits. Pits are excavated and the soil profile logged, including texture, structure and any restrictive layer.
- Water table determination. Depth to seasonal high water table, which in the valleys is often the controlling constraint.
- Setback mapping. Wells, surface water, structures and boundaries are located and the available area established.
- Design. The system is designed to fit what the evaluation found, and submitted for review.
What drives the price
Cost expectations
We do not publish a price, because a number quoted without seeing the property is a guess and you would be right to distrust it. What we can tell you is what moves the figure, so you know what a company is looking at when they price the job.
- Number of test pits required, which rises on variable or large parcels
- Whether the ground supports a simple design or requires engineering
- Site access for the excavator digging test pits
- Whether a seasonal water table determination is needed, which can be time-of-year dependent
- Parcel size and how much of it has to be evaluated to find a viable area
A real number comes from a site visit by a certified company. If two quotes differ a lot, the usual reason is one of the items above, and it is fair to ask which.
Where
Available across Pierce County
Common questions
Questions about septic design and site evaluation
Why is a site evaluation needed if a system was already there?
A replacement still has to be designed for current standards and for the area actually available now, which may differ from what existed when the original was installed. The old as-built informs the work but does not substitute for it.
Can a parcel fail to support any system?
It can. Shallow bedrock, very high water table, insufficient area or setback conflicts can all rule out a conventional system, and sometimes the answer is an engineered design that costs considerably more.
When is the best time of year for an evaluation?
Where the seasonal high water table is the controlling factor, wetter months give the more conservative reading. Ask the designer whether timing matters on your parcel.
Should I evaluate before buying land?
Yes, if the parcel will need an on-site system. A feasibility evaluation before purchase is much cheaper than discovering after closing that the land cannot carry a system you can afford.
Request a match
Get matched with a certified Pierce County company
Your request goes to an on-site sewage professional certified by the Tacoma-Pierce County Health Department and serving Pierce County, not a national lead list.
The request form is not accepting submissions yet. This site is new and the intake line is still being set up. Until it is live, nothing is collected here, because a form that renders but delivers nowhere is worse than no form at all.
Prefer to talk? Call (253) 367-7679.