So, the health department allows a 25% reduction in drainfield absorption trench bottom area when substituting synthetic aggregate for gravel.  This basically increases a 3-bedroom site to a 4-bedroom site.  Any reasonable person with any basic understanding of onsite sewage systems would agree that this is ridiculous (eek, this sounds similar to what the FBI director said about H.C. just before he reached his ridiculous conclusion).  When will the Virginia Department of Health start using common sense rather than caving to manufacterers?  Just bite the bullet and give a 25% reduction for all materials including gravel, i.e. reduce the square footage requirements in the gravity column in Table 5.4 in the Sewage Handling and Disposal Regulations to reflect the 25% reduction for all materials.  Well, I suppose if VDH did this, the manufacturers would probably request another 25% off.  This is ridiculous.