For nearly the past last 20 years in Virginia, drip dispersal field footprints have been equivalent in size to low pressure distribution drainfield footprints.  Drip field footprints were increased in size due to slope just as low pressure distribution fields were increased in size.  The center-to-center spacing of low pressure distribution trenches is increase by 1 foot for every 10 percent of slope.  Therefore, on a 25% slope, the center-to-center spacing of two-foot wide LPD trenches would be increased from 6' to 8' which is a 33% increase in dispersal area.  The same 33% increase has been applied to drip dispersal fields.  However, this regulation eliminates the slope correction factor which will dramitically decrease the size of a drip dispersal field footprint.

What empirical evidence was used to make this decision?  It appears the Virginia Department of Health is making a major change with this regulation with no scientific basis to do so.  This is no different than eliminating the requirement to increase the center-to-center spacing for trenches on slopes.  Will VDH consider this?

Experiments are done for a reason.  Drip was tested in a specific manner for nearly 20 years in Virginia.  Apparently the experiment was successful.  But now VDH is rescinding the drip GMP protocol and adopting this regulation which is significantly different than what was tested.

Eliminating the slope factor should be a 32.1-163.6 design decision made by a private sector licensed professional engineer.  Where does 32.1-163.5 stop and 32.1-163.6 begin?

Please bring back the slope factor for drip dispersal.