12VAC5-613-80 of the Proposed Regulations mixes both performance and prescriptive requirements without differentiation. Only performance requirements apply to designs pursuant to 32.1-163.6:
·Item 4 should be omitted – see comments above related to DEQ permitting authority. As written this item refers to Section 90 C, which is both prescriptive, and performance.
·Item 5 should be modified to read: All AOSSs shall be designed for the anticipated receiving wastewater strength and flow.
·Item 7 is prescriptive a prohibition must be written in terms of ultimate performance, not simply declared.
·Item 11 is prescriptive - Trench Bottom Loading Rates is prescriptive (prescribes loading rates based on specified soil perc rates). The recommended modification should read: The soil treatment area shall be adequately sized to accommodate the hydraulic capacity of the underlying soil.
·Item 12 is prescriptive and should be omitted.
·Item 13 is a prescriptive declaration of vertical separation for prescribed treatment levels is the definition of prescriptive. Additionally, there is no statutory authority for vertical separations. The recommended modification should read: For any small AOSSs where the vertical separation to a limiting feature is less than 18 inches below the soil treatment area and for any large AOSS, regardless of site constraints, the designer shall provide calculations to demonstrate that water mounding will not adversely affect the functioning of the soil treatment area, that hydraulic failure will not occur, and that adequate vertical separation will be maintained to ensure the performance requirements of this chapter are met.
·Also recommend a new item that reads: For any system in which artificial drainage is proposed, the designer shall provide calculations and other documentation sufficient to demonstrate the effectiveness of the proposed drainage, except where an outlet daylights downgradient from the drainage area
·Item N is prescriptive because it specifies specific treatment levels to vertical separation depths.
·Item O is performance but the loading rate (0.00021) is incorrect. The prescriptive organic loading rates for SEPTIC systems ranges much higher than this limit (0.0015 to 0.0002 for soil rates ranging from 5 minutes per inch to 110 minutes per inch). Recommend the following: The organic loading rate shall not exceed 0.0005 lb/day/sf BOD5 on a trench-bottom or aerial basis, as appropriate
12VAC5-613-90 of the Proposed Regulations mixes both performance and prescriptive requirements without differentiation and creates standards that exceed the statutory test of for systems otherwise permitted pursuant to the regulations.
Item A is performance but sets the wrong fecal coliform limit. The statutory groundwater standard for systems otherwise permitted pursuant to the regulations is 200 cfu/100 mil, not 2.2.
Item B is performance but it is not clear that a Total Nitrogen (TN) limit of 5 mg/l is consistent with the statutory groundwater standard. VDH should be required to demonstrate that this standard is routinely met by systems otherwise permitted pursuant to the regulations.
Item C.1 is performance, but fraught with peril and uncertainty. The DEQ groundwater standard (9VAC25-280) lists 31 organic/inorganic constituents and 8 radioactive elements. Does this reference imply that homeowners would have to routinely or periodically test for all these constituents that are not normally associated with domestic wastewater. The only constituents listed that are routinely associated with domestic wastewater are: ammonia, and nitrate. Since aerobic treatment systems do a great job of nitrification – that leaves nitrate as the only meaningful constituent.
Item C.2 is redundant and there are problems associated with referenced section 100.G., principally the quarterly sampling that will quadruple the O&M costs to a residential system owner (eg. homeowner).
Item C.3 is performance based but again does not comply with the statutory effluent or discharge standard for systems otherwise permitted pursuant to the regulations.
Item C.4 is prohibitive, therefore prescriptive.
Item C.5 is prescriptive.
Item C.6 doesn’t belong in a performance requirement rather should be in the administrative section. And there are significant issues with a renewal permit chief among them, the considerable risk to the permit holder (homeowner, developer, community association) that requirements may change that would require significant costs to renew a permit.
Item D is prescriptive. In addition, VDH has no statutory authority within the operative Notice of Intended Regulatory Action (NOIRA) to set a Nitrogen limit or standard that is more restrictive than standard for systems otherwise permitted pursuant to the regulations.
Item E is prohibitive, therefore prescriptive. For systems located in wetlands, it must be clarified that the wetlands classification is non-tidal. There are sufficient prohibitions already in place to protect tidal wetlands, such as shellfish water regulations and Chesapeake Bay Preservation Act buffer requirements. Designs typically treat the wastewater to secondary standards then disinfect. At this point they exceed all statutory requirements for systems otherwise permitted pursuant to the regulations. Dispersal to an elevated sand mound adds tertiary treatment prior to entering the natural environment. The final effluent that enters the wetland environment is "cleaner than creek water" except for the nutrient levels, which are attenuated within the natural environment. Research shows that wetlands are not so great at providing secondary treatment - but do a great job of mitigating nutrients from an otherwise "clean" effluent. VDH should demonstrate the science or empirical data that validates this proposed prohibition.
Recommend the following as a replacement for Section 90:
12VAC5-613-90. Ground Water Protection.
A. The AOSS shall not pose a greater risk of ground water pollution than systems otherwise permitted pursuant to 12VAC5-610.The concentration of fecal coliform organisms must not exceed 200 cfu/100 ml at the terminus of the treatment works.
B. Each large AOSS shall comply with TN limit of 5 mg/l at the project area boundary. Prior to the issuance of a construction permit, the designer shall demonstrate compliance with this requirement through modeling or other calculations. Such demonstration may incorporate multiple nitrogen removal methods such as pretreatment, vegetative uptake (only for AOSSs with shallow soil treatment areas), denitrification, and other viable nitrogen management methods. Ground water and other monitoring may be required at the department's discretion.
C. All small AOSSs in the Chesapeake Bay Watershed shall provide a 50% reduction of TN as compared to a conventional gravity drainfield system.
D. The engineer shall identify the point of compliance for effluent sampling and corresponding effluent quality standard. When required, the sampling point for chlorine disinfection shall be at the end of the chlorine contact tank if TRC is to be used to measure compliance.
12VAC5-613-100 – does not belong in Part II – move to Part III.
12VAC5-613-100 G. – recommend the following replacement language: Systems with direct dispersal to groundwater shall comply with the following:
12VAC5-613-100.G.a – is unclear. Is this a requirement for telemetry to notify the operator and local health department of an alarm condition (typically high water, loss of air flow, or disinfection)? Anything other then these basic parameters are unobtainable. Recommend the following replacement language: Shall include telemetry and automatically notify the operator and local health department if an alarm condition occurs related to the disinfection unit, aerator malfunction or a high water condition within a pump or treatment tank.
12VAC5-613-100.G.b – should be omitted. It is excessive and will cost owner’s 4x the maintenance cost of similar systems.
12VAC5-613-100.G.c - should be omitted. It is excessively restrictive.
12VAC5-613-100.G.2 – should be modified to read: Large AOSSs must be continuously monitored for the proper operation of all treatment units. If the wastewater treatment works is not manned 24 hours a day, telemetry shall be provided that monitors all critical systems, including turbidity into the disinfection unit and the functionality of the disinfection unit, and notifies the operator of alarm conditions.
12VAC5-613-110 - does not belong in Part II – move to Part III.
