Proposed Nitrogen Standard (12VAC5-610-90.D.1.b.ii)
As part of my review of the proposed VDH regulations I've been looking closely at the EPA and DCR nitrogen model compared to the proposed regulations. What I find is stunning.
Based on the EPA/DCR model and the VDH proposed rule, A Conventional Septic Tank/Drainfield System achieves a Nitrogen Loading Rate that is 50% below the allowable of 4.5 lbs per year per person.
Again - A Conventional Septic Tank System would comply with VDH's proposed Nitrogen rule by a factor of 2 using the EPA/DCR model.
An alternative system acheives a 50% reduction in Nitrogen compared to a conventional septic system. So an alternative system would currently comply with VDH's proposed rule by a factor of 4.
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If we really and truly want to reduce the Nitrogen loading to the Bay, we have to start talking about the elephant in the room. That is the 500,000 or so existing conventional systems in the watershed. If we simply added a secondary aerobic treatment unit to every conventional system, we would reduce the Nitrogen discharge by 50% - or 1.45 million lbs per year (EPA esimates that Virginia's septic systems contribute a total of 2.9 million lbs of Nitrogen annually).
But what we are doing with this proposed rule is over-regulating about 1,000 new systems per year that only add up to about 10,000 pounds of Nitrogen annually, roughly 0.3% of the total septic contribution (based on the annual contribution of 2.9 million lbs according to DCR/EPA).
So where does the 1,000 systems per year come from. These are the "engineered" systems that the new "performance" regulations target. VDH issues about 30,000 onsite permits each year. VDH estimates that 22% of onsite system are alternative - 22% of 30,000 = 6,600 systems. Of these, AOSE's design 85% or more. So 15% of 6,600 = 990 systems.
Why are spending so much time and energy over-regulating 1,000 engineered systems (3% of the annual total) that are doing a significantly better job of treating wastewater than a conventional system?
