-why not just say 20,000 pound crush strength for gravelless pipe, instead of H-10 or H-20 (AASHTO) (12VACS5-610-930, F.2.f)

-Why is gravelless area less than gravel area in df size, what justifies it? (Table 5.4 and text –950, D.2)

-Drip dispersal B.3 requires 6 inches, manufacturers like to recommend install at 4 inches, justification either way? (–955, B.3)

The new addition of B.6. addressing emitter aspiration at depressurization is an element of the requirement C.4 for the placement of air relief valves.  Item “D” regarding prevention of gravity redistribution is also related.  Proper placement of air valves, coupled with appropriate piping configuration to prevent redistribution will minimize aspiration of particles into the emitter at end dose event depressurization.    Certain self-cleaning emitters will not clog due to aspiration as they are continuously self purging during operation.  B.6. is redundant. Removal of B.6 is recommended.

Regarding additional specific language to 610 955 C.3.C.3., the addition of actual design criteria may be in conflict with the elements of 12VAC5-613-80. Performance requirements; general. 12 a.b.& c.

As a pressurized dispersal system, drip dispersal systems, as Low Pressure Distribution Systems, are engineered “Alternative Systems” subject to 12VAC5-613.  12VAC5-613-80. 12 a.,b.,& c.  outlines the site specific considerations that must be addressed by the engineer in system design regarding specific site soil hydraulics.

Absorption area geometry is an important consideration in sites with shallow soil depths to limitations and larger flow systems in all slope classes.

Should Hydralic Linear Loading design criteria be applied to LPD systems?  Large flow systems?  Gravity 613 systems?

All systems >1000-1200 GPD require considerably more site hydraulic evaluation then as provided by prescriptive design values.

The concept of and specific design guidelines (specific values) for “Landscape Linear Loading” or “Hydraulic Linear Loading” have their origins in traditional above ground (mound) systems. The values are recommendations with considerable narrative discussion addressing site specific soil and landscape conditions.  Appropriately sized in situ dispersal involves addressing additional absorption dynamics as addressed in 12VAC5-613-80. 12.  The requirements (“shall”) in 610-955 C.3. are out of place.     The entire text of 610-955 C.3. should be removed.

VDH OSE designs include specifications which provide a 25% reduction in area for infiltration with a substitution worded as follows:
“Gravel-less material may be used, in lieu of gravel and pipe, within the approved distribution area in accordance with Table 5.4 of 12VAC5-610. If gravel-less material is used the distribution box location remains the same”

This statement leaves critical factors open to interpretation. Please address the following examples:

1. To date VDH construction permits do not offer guidance or specifications for corresponding alterations in systems designed with pump or siphon dosing.

Could VDH offer guidance on who is responsible for alteration of the pump design to reflect the change in area and/or number of trenches?

2. The statement does not clarify whether the selection of materials is made by a contractor, a homeowner, or the designer (PE or OSE).

How does the VDH intend to amend policy requiring design of onsite systems to conform with the engineering responsibilities of the licensed designer?

3. The onsite wastewater system design is under the auspices of the professional engineering the system, this includes source, conveyance and dispersal.

Does the substitution of specified generally approved products require endorsement by the designer subsequent to the issuance of the permit, and does the public have any reliable means to discern the responsible charge for this alteration?

4. To date contractors have been expected to counsel their clients regarding the installion of a onsite sewage systems with only 75% of the prescribed surface area. The manufacturer claims:

"Chamber systems are easy to install. Engineered for strength and performance, they have greater design flexibility including a smaller footprint as compared with stone and pipe, and are made from recycled materials. These advantages of Infiltrator chambers add up to cost savings on labor, materials and time savings on the job." (emphasis addedd)

How will the VDH assure the public that the consumer has been advised regarding increased area loading rate, and risk of reduced system performance?

5. VDH central staff responded to a request for gravel-less system performance statistics with the following statement: "...there is not currently a standard VENIS report for the malfunction report that I can pull to provide you with the requested sample data."

In light of the record of usage dating to 1991, and controversy amongst some designers in disparate regions when will VDH provide a public accounting of systems in place, and malfunction assessment associated with repair statistics?

The Board of Health may want to incorporate language for utilization of submersible turbine pumps and do away with the narrowly worded requirement under 12VAC5-610-880 B.6:

6. Pumps. All pumps utilized shall be of the open face centrifugal type designed to pump sewage.