Protecting & Restoring Long Island's Peconic Bays
According to Article 6 of the Suffolk County Sanitary Code beginning on July 1, 2019, when property owners determine that their septic systems need to be replaced or retrofitted, approval for the replacement or retrofit must be obtained from the Suffolk County Department of Health Services (SCDHS). The new system must conform to current standards, which require, at a minimum, a septic tank preceding a leaching structure. Beginning onJuly 1, 2021, I/A OWTS for new or expanded single-family residences and New Other Construction Projects, which are permitted to use an Individual Sewerage System or Subsurface Sewerage Disposal System, are required. In addition, requirements are established for the use of I/A OWTS for pre-existing Other Construction Projects that exceed the Population Density Equivalent requirements of Article 6 (Suffolk County 2020b). The Towns of East Hampton, and Southampton require the use of I/A OWTS for new construction or substantial reconstruction town-wide (East Hampton) or in town identified high priority areas (Southampton). Current and future flood risk, sea level rise (SLR), and current and future depth to groundwater should be considered in the evaluation of the appropriate I/A OWTS. In areas where the groundwater table is high under current or future SLR scenarios, I/A OWTS with pressurized shallow drainfields are appropriate (CDM 2020). Recent mapping available through the PEP Climate Ready Assessment will enable evaluation of current and future SLR and depth to groundwater scenarios. (Anchor QEA 2019; https://gis.anchorqea.com/PeconicEstuaryCLPS/).
The following permits are required for installation of approved I/A OWTS:
Suffolk County is promoting installation of approved residential I/A OWTS through financial incentives as part of the Suffolk County Septic Improvement Program and New York State Septic Replacement Program. Grants provide up to $30,000 from Suffolk County and New York State to offset the cost of one of the new systems. Low-cost financing is also available to homeowners who qualify. Eligibility and the amount of grant awards are based on a number of criteria, including home ownership and income level, and are prioritized based on density, geographic location, and status of current system. Grant applications for approved systems are assigned points based on whether they are inside or outside a Suffolk County Priority Critical Area (where the groundwater travel time is 0 to 2 years as defined by the Suffolk County Comprehensive Water Resources Management plan, or within 1,000 feet of a surface water body) or whether or not their current septic tank has experienced failure.[2] Funding is contingent upon approval of the installed system by Suffolk County and a commitment to long-term effluent monitoring. Detailed grant information and application materials are provided by Suffolk County through the Septic Improvement Program website (https://reclaimourwater.info/SepticImprovementProgram.aspx).
Additional funding may also be available depending on location. The towns of Southampton, East Hampton and Shelter Island offer extensive rebates programs that can be combined with county and state funds to further incentivize I/A OWTS.
[2] The greatest number of points (100) are given to residences that are both within a Priority Critical Area (70 points) and their current septic system has experienced failure (30 points). Eligible applications from residences in Critical Areas (2- to 25‑year groundwater travel time) are assigned 60 points. Qualifying residences outside of the Priority Critical or Critical Areas receive only 50 points. All applicants that have a documented catastrophic failure of an existing system may receive an additional 30 points. Grants are not available for new construction on vacant lots or in areas served by a sewer system.
The extent of nitrogen removal varies among the different systems, but all provisionally approved systems reduce nitrogen to an average below 19 mg/L during pilot testing of eight systems for one year. To gain full approval, systems must demonstrate three years of data from 20 systems with an average of less than 19 mg/L. Some, but not all, provisionally approved systems are on track to meet this criterion.
The influent source for septic systems is septic tank effluent, with a concentration of 65 mg/l (CDM 2020). The range of total nitrogen effluent concentrations are based on the most recent 12-month rolling average and the cumulative bi-monthly sampling results, respectively (Suffolk County 2020b). The nitrogen removal rates for approved I/A OWTS for a 4-bedroom household (440 gpd) are provided in the table below.
Individual I/A OWTS Nitrogen Effluent Concentrations, Nitrogen Reduction, and Annual Removal Rates
| Technology | Effluent Nitrogen Concentration (mg/L) | Nitrogen Reduction (%) | Annual Nitrogen Removal (lb/yr) |
|---|---|---|---|
| Hydro-Action AN Series | 9.43 – 10.5 | 84 – 85 | 73 – 74 |
| Norweco Hydro-Kinetic | 18.2 – 19.7 | 70 – 72 | 61 – 63 |
| SeptiTech STAAR | 14.5–15.1 | 77–78 | 67–68 |
| Orenco Advantex AX-20 | 9.5 | 85 | 74 |
| Fuji Clean CEN Series | 11.2 – 11.4 | 84 – 86 | 72 |
Capital and operations and maintenance costs and nitrogen benefit assumptions are detailed in Suffolk County (2021) and are based on a 4-bedroom household (440 gpd). Capital costs include a design and engineering cost of $2,500 and are provided for the three types of installations, with reuse of existing leaching structure, and with replacement with either a gravity leaching structure, or a pressurized drainfield. An additional $500 for backfill is added to capital costs for scenarios that replace the existing leaching structure. Operations and maintenance (O&M) costs include power, and consumables, and parts repair and replacement over 20 years with a 2% inflation rate applied. Electric power costs are based on $0.22 per kilowatt hour (kWh; Suffolk County 2020c). The total annualized costs include capital costs annualized with a 5% discount rate and the annual average O&M cost. The cost range includes the least and most expensive vendor referenced for each technology by Suffolk County through the Septic Improvement Program website (https://reclaimourwater.info/SepticImprovementProgram.aspx).
Individual I/A OWTS Capital, O&M, Total Annualized Costs, and Costs per Pound of Nitrogen Removed
| BMP Type | Technology | Capital Cost | Average Annual O&M Costs | Total Cost* | Cost per Pound N Removed |
|---|---|---|---|---|---|
| I/A OWTS – Individual Reuse of Existing Leaching Structure | Hydro-Action AN Series | $17,550–$25,878 | $736–$806 | $2,144–$2,812 | $29-$38 |
| Norweco Hydro-Kinetic | $18,198–$24,646 | $871–$903 | $2,332–$2,849 | $37-$47 | |
| SeptiTech STAAR | $16,400–$25,910 | $754–$780 | $2,070–$2,833 | $31-$42 | |
| Orenco Advantex AX-20 | $20,047 | $737 | $2,346 | $32 | |
| Fuji Clean CEN Series | $16,590–$27,765 | $620–$712 | $1,951–$2,848 | $27-$40 | |
| I/A OWTS – Individual New Gravity Leaching Structure | Hydro-Action AN Series | $20,450–$30,608 | $736–$806 | $2,377–$3,192 | $32-$44 |
| Norweco Hydro-Kinetic | $29,826 | $871–$903 | $2,585–$3,265 | $41-$54 | |
| SeptiTech STAAR | $20,400–$29,242 | $754–$780 | $2,391–$3,100 | $35-$46 | |
| Orenco Advantex AX-20 | $23,447 | $737 | $2,618 | $35 | |
| Fuji Clean CEN Series | $19,400–$30,650 | $620–$712 | $2,176–$3,079 | $30-$43 | |
| I/A OWTS – Individual Pressurized Shallow Drainfield | Hydro-Action AN Series | $24,229–$36,162 | $736–$806 | $2,680–$3,637 | $36-$50 |
| Norweco Hydro-Kinetic | $24,923–$37,937 | $871–$903 | $2,871–$3,916 | $46-$65 | |
| SeptiTech STAAR | $37,202 | $754–$780 | $2,554–$3,750 | $38-$56 | |
| Orenco Advantex AX-20 | $26,954–$26,954 | $737 | $2,900 | $39 | |
| Fuji Clean CEN Series | $23,615–$36,505 | $620–$712 | $2,515–$3,549 | $35-$50 |
*Annualized total costs over 20 years.
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