Site Evaluation and Septic Design
The Basics of a Site Evaluation
There are many things which must be considered when evaluating a site for a septic treatment system but these are the main considerations that must be taken into account.
• Identifying any elements that might effect the suitability of the parcel for septic services. These include things like water wells, water sources, lakes and rivers, drainage areas, swampy areas or exposed or near surface rock ledgers. It is also important to identify the slope and direction of the slope of the land and how it will affect both the surface drainage and where the effluent from the system will go.
• Identifying the best location on the site for the septic treatment area.
• Dig two test pits approximately 9 feet deep.
• Logging the soils horizons (layers) in the two test pits to identify soil structure and soil types.
• Verifying the level of ground water or seasonal saturation if this is closer than nine feet from the surface.
• Collecting two samples of the most restrictive layer of soils and having them analyzed at an accredited lab.
A system design is based on two concerns.
How much effluent will the house produce and how well can the on site soils treat this amount of effluent.
• The amount of effluent that is expected to be produces is based on the number of bedrooms in the house as well as the overall water usage of the occupants.
• How well the soils can treat the effluent is based on the soils log (the soil structure) and the results of the lab work (the soil type or texture).
Why does the County ask for a PSDS Site Evaluation prior to subdivision?
• This report gives the County assurances that if the acreage is created, there will be a place where the septic can safely be treated. This should prevent low lying and swampy lots from being subdivided to create homesteads that will always have sewage problems. It can also help to determine the minimum size of the acreage. At a minimum, a quarter of an acre of good land is needed for a septic treatment area. It is easier to build the house in the swamp then to design an effective septic treatment system in a swamp.