Note: For use in calculating septic system density allowances applicable to: a) the Planning Area, generally; b) the developed portion of a cluster development project in the Preservation Area, where overall yield is determined by NJDEP Preservation Area Rules; and c) non-Major Highlands Development in the Preservation Area where not exempt from the Highlands Act.
The model Highlands Area Land Use Ordinance provides two methods by which the septic system yield may be calculated for a development project in the Planning Area of a conforming municipality (see Section 5.3). The default method relies on Highlands Council calculations of the maximum septic system density (i.e., minimum average lot size per septic system), based on the HUC14 subwatershed drought recharge and the applicable nitrate target for the Land Use Capability Map (LUCM) Zone (referred to as "Highlands Zones and Sub-Zones" in the model Land Use Ordinance). Under this method, all development project lands in each LUCM Zone of each HUC14 subwatershed are assigned the same maximum septic system density. A chart is available at the following link providing the minimum average lot size required per septic system, by HUC14 for each LUCM Zone.
The alternative method allows for a parcel-specific analysis of septic system density for conventional subdivisions in the Planning Area only. This alternative method cannot be used to calculate the septic system yield for conventional subdivisions in the Preservation Area; applicants must use the standards described in N.J.A.C. 7:38-3.4(b).
The alternative method must be used to determine the maximum septic system density of residential cluster developments, either in the Planning Area or the Preservation Area. The Highlands Council, with the permission of the New Jersey Geological Survey, has created a version of their "A Recharge-Based Nitrate-Dilution Model for New Jersey V6.2" for use in the Planning Area of the Highlands Region. This new model is "A Recharge-Based Nitrate-Dilution Model for the Highlands Region V1.0."
(NOTE: Regardless of the method used, septic system density is only one potential determinant of development yield. The Highlands Land Use Ordinance addresses additional requirements that may further limit development potential to less than the septic system yield. The approvable development yield is a combined result of all Ordinance requirements. Development yield may also be further limited by insufficient developable sites or septic system locations, as regulated by underlying municipal ordinances and Board of Health requirements.)
Please use the link below to download "A Recharge-Based Nitrate-Dilution Model for the Highlands Region V1.0." The following restrictions and notes apply to use of the model:
Calculation of Septic System Density
Calculation of Septic System Yield
Calculation of Septic System Density for Cluster Developments