In response to an adjudication issued by the Pennsylvania Environmental Hearing Board (EHB) in late 2011, the Pennsylvania Department of Environmental Protection (PADEP) has issued a proposed policy that, if finalized, would guide its review of sewage facilities planning modules proposing the use of individual and community onlot sewage systems in High Quality (HQ) and Exceptional Value (EV) watersheds.
Under Pennsylvania’s Act 537, when a new subdivision is proposed, municipalies are required to submit a completed sewage facilities planning module to revise the comprehensive official plans that they develop and implement to resolve existing sewage disposal problems and provide for the future sewage disposal needs. In Pine Creek Valley Watershed Ass’n, Inc. v. DEP, et al., EHB Docket No. 2009-168-L, the EHB rescinded PADEP’s approval of one such planning module submitted by District Township for a subdivision to be served by on-lot septic systems in an EV watershed.
The EHB held that PADEP had failed to demonstrate that the water quality of a receiving EV stream would be maintained and protected as Pennsylvania’s (federally mandated) antidegradation program requires, see 25 Pa. Code § 93.4a(d) (“The water quality of Exceptional Value Waters shall be maintained and protected”). Simply stated, the EHB rejected PADEP’s conclusion that an onsite EV wetland would denitrify effluent plumes so effectively that nitrate concentrations as high as 20 mg/l would be less than 0.84 mg/l (the water quality of the EV stream that was required to be maintained and protected) when they merged into the EV stream.
PADEP’s proposed policy, “Sewage Facilities Planning Module Review for Onlot Sewage Systems Proposed in High Quality and Exceptional Value Watersheds,” seeks to respond to (and avoid another outcome like) the Pine Creek decision. Although acknowledging that the EHB based its decision in Pine Creek on 25 Pa. Code § 93.4a, PADEP finds support for the best management practice (BMP)-based approach that it sets forth in the policy in 25 Pa. Code § 93.4c, and, more specifically, § 93.4c(b)(2), which provides that “[t]he Department will assure that cost-effective and reasonable best management practices for nonpoint source control are achieved [for the protection of High Quality and Exceptional Value Waters].”
Before setting forth its BMP-approach, the policy provides a useful primer on onlot sewage systems and water quality. Here’s an abbreviated version: Properly designed, located, installed and maintained septic systems, via anaerobic processes in a septic tank and aerobic processes in a soil absorption field, are capable of treating nearly all of the typical pollutants of concern in sanitary wastewater treatment. Some inorganic compounds, however, may not be effectively removed. Of these, only nitrate has been demonstrated to have substantive far-field effects on water quality in groundwater and surface water, which makes it the pollutant of concern from onlot systems.
Nitrate is a natually-occurring compound that comes from a variety of sources. Nitrate in groundwater is a human health concern as it can lead to a disorder called methemoglobinemia. Nitrate in surface waters poses a threat to aquatic life and recreational water uses. Nitrate removal occurs naturally in groundwater (and to some extent, in surface water) through denitrification, plant uptake, and microbial immobilization. Minimum isolation distances set forth in regulations are not always sufficient to protect water supply wells and surface waters from nitrate. It is difficult to project the water quality effects of onlot systems where the fate of nitrate flow through the subsurface to surface waters is not well characterized.
As alluded to above, the policy proposes a BMP-based approach to nitrate removal. First, the policy identifies a number of accepted BMPs. These include onlot system density, setback distances, riparian forest buffers, riparian buffers, permeable reactive barriers, and denitrifying onlot treatment system technology. Then, the policy assigns each BMP one or more protection factors (e.g., the policy assigns three different protection factors for three different ranges of setback distance) and explains the scientific justification underpinning the protection factors assigned. Finally, the policy provides that “[t]he total protection factor for a system is calculated by multiplying the individual protection factors for each proposed BMP” and that “the product of all BMP protection factors should be at least 45.”
Why 45? Because, as the policy notes, the typical nitrate concentration in septic effluent is around 45 mg/L. And as the policy explains:
“Precipitation and groundwater contributions generally average approximately 1 mg/L nitrate-N in the absence of local and substantial anthropogenic sources. Considering the uncertainty associated with quantitative estimates of the effectiveness of BMPs for nitrogen removal and also that base levels of nitrate-N in precipitation and groundwater already may be 1 mg/L, the product of all BMP protection factors should be at least 45 to ensure consistency with the antidegradation requirements of Chapter 93. A total protection factor of 45 is designed to reduce nitrate concentrations by a factor of 45; that is, from 45 mg/L nitrate-N to approximately 1 mg/L nitrate-N . . . . By selecting and implementing BMPs with a total protection factor of 45 or greater, the water quality in the HQ or EV water is expected to be maintained and protected.”
The policy provides some helpful examples to illustrate how the approach might work in practice, describes how the use of these BMPs should be addressed in official sewage facilities plans and sewage facilities planning modules, and explains how permitting for onlot sewage systems in HQ and EV watersheds would work under the policy.
DEP is accepting comments on the proposed policy through June 3. In the meantime, certain members of the Pennsylvania General Assembly are working to supersede the policy through legislation. Representative David Maloney (R-Berks) introduced a bill (HB 1212) that would amend the Clean Streams Law to provide that PADEP may not require antidegradation requirements for onlot systems in conjunction with their planning and permitting. Whether such a law would contravene federal Clean Water Act requirements is an open question.
Considering the difficulty involved in projecting the water quality effects of individual onlot systems in HQ and EV watersheds, the proposed policy strikes me as a sensible and justifiable approach to addressing the problem presented by the Pine Creek decision. Whether that approach would satisfy the EHB is also a question for another day.