Rule R317-401. Graywater Systems
At about 5 pages in length, the code is relatively straightforward. Unfortunately it is focussed on disposal, rather than beneficial use of the graywater.
A permit is required.
Here are the key points:
- Sub surface irrigation dripperlines must buried at a minimum depth of six inches. Drip feeder lines can be polyethylene or flexible PVC tubing and shall be covered to a minimum depth of six inches.
- Agency shall issue a renewable operating permit at a frequency not exceeding five years with inspection of the permitted systems before renewal; or, inspect annually the greater of 20 per cent of all installed system or the minimum of ten installed systems
- Designer certified at Level 3, in accordance with the requirements of R317-11, shall design the graywater systems.
- at least 250 gallons in volumetric capacity to provide settling of solids, accumulation of sludge and scum unless justified with a mass balance of inflow and outflow and type of distribution for irrigation;
- The local health department may require the following information with or in the plot plan before a permit is issued for a graywater system:(i) plot plan drawn to scale, completely dimensioned, showing lot lines and structures, direction and slope of the ground, location of all present or proposed retaining walls, drainage channels, water supply lines, wells, paved areas and structures on the plot, other utilities, easements, number of bedrooms and plumbing fixtures plan in each structure, location of onsite wastewater system and replacement area of the onsite wastewater system, or building sewer connecting to a public sewer, and location of the proposed graywater system;(ii) a log of soil formations and identification of the maximum anticipated ground water level as determined by the minimum of one test hole, dug in close proximity, two feet below the bottom of the subsurface irrigation field or drip irrigation area together with a statement of types of soil based on soil classification at the proposed site. Soil and groundwater evaluations will be conducted by professionals fulfilling the requirements of R317-11;
Analysis and Discussion of the Code
The key issue with this code (for gardening and water conservation purposes) as having to place the dripperlines at least 6” below surface level.
Because of this, irrigation efficiency decreases substantially. In addition more dripperline must be used ($$) and higher levels of filtration are required.
The requirement for 250 gallons of storage capacity is not a significant issue, because if sufficient dripperline is installed to irrigate at peak flow rate (mass balance of inflow and outflow) the tank can be any size.