Your local environmental health department will likely be the first place you go for help with a septic drain field design.
The Local Env Health Department representative will come out, perform a site and soil assessment and will give you a preliminary indication of whether or not a conventional septic system is a possibility.
If a conventional septic system is possible, they will likely do a rough design for you. The folks at the local health department are oftentimes very experienced in drain field design and will be able to draw up a good design pretty quickly and easily.
Keep in mind however, that their goals and your goals may not line up perfectly, and the design you receive from them may not get you the ideal result you are after.
If the design takes up too much of the property or is inconveniently located on the property the environmental health specialist may mention that you could hire a soil scientist to assess the property and do a design using innovative products.
Some of these products get automatic reductions in required drain field area.
An example scenario:
3 bedroom home = 360 gallons per day design
LTAR = .3gpd/sqft (LTAR = long-term acceptance rate) LTAR tells you how many gallons of wastewater per day per sq ft you can apply to the soil long-term and the drain field not fail.
Square feet of Drain field needed = GPD/LTAR
In this case: 360gpd / .3gpd/sqft = 1200sqft of usable area
A Conventional design would require 1200 sq ft of primary drain field area and 1200 sq ft of designated usable repair area for a total of 2400 sq ft of drain field or disposal area for a conventional design. Your local health department is not allowed to do design with proprietary products such as advantex treatment systems, geoflow drip irrigation, ez-flow, t&j panel etc.
A 25% reduction would reduce your primary and repair respectively by 25% resulting in only 1800 sq ft being required instead of 2400 sq ft.
There are a handful of innovative drain field products that get automatic drain field area reductions of up to 50%. All of these products are not approved in every county, and some of the products require very specific soil conditions.
Soil consultants are often very familiar with local rules and best practices and are an invaluable resource. Email me for recommendations for a soil consultant in your area - email@example.com
If a simple drain field area reduction isn't going to cut it then treating the wastewater to a TS-1 or TS-2 treatment standard before dosing it to the drain field may be what you need to get the highest and best use of your land.
Treatment like the AX20RTUV allows you to either 1) reduce the size of your drain field 2) reduce horizontal set backs to things like wells and surface water and/or 3) reduce the depth of soil needed between the bottom of your drain field trench and the seasonal high water table.
If you think your situation needs treatment or if you are considering how best to develop a piece of land with different septic approaches reach out.
Send any plan and soils work you already have to Michael at firstname.lastname@example.org or call 252-243-7693
If the home you are building is an investment or rental property like an oceanfront rental house in the OBX or crystal coast, you really should consider how innovative approaches to onsite wastewater can increase the number of bedrooms, pool size, density of lots and more that will add money to your weekly income check.