Tables: Manufactured Treatment Devices — Small-Scale GI¶
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1. Table 1¶
| N.J.A.C. 7:8 Stormwater Management Rules – Applicable Design and Performance Standards | ||
|---|---|---|
| Green Infrastructure | Yes | |
| Stormwater Runoff Quantity | Not Allowed | |
| Groundwater Recharge | Not Allowed | |
| % | Stormwater Runoff Quality | 80% TSS |
Source context and notes
# Manufactured Treatment Devices — Small-Scale GI Source revision: July 2023. # 9.5 MANUFACTURED TREATMENT DEVICES (GI) Manufactured treatment devices (MTDs) are proprietary stormwater treatment systems used to address the stormwater runoff quality impacts of land development and rely upon a variety of mechanisms to remove pollutants from stormwater runoff. There are two types of MTDs currently certified by the Department: hydrodynamic sedimentation (HDS) devices and filtration devices. Most of these devices are not approved for use as a green infrastructure BMP (See Chapter 11.3: Manufactured Treatment Devices (Non-GI)) because they do not manage stormwater close to its source either by infiltration into subsoil, treatment by vegetation or soil or storage for reuse. A subset of MTDs rely upon specialized technology and incorporate an engineered, high-flow rate filter media to remove stormwater pollutants, allowing for a smaller footprint than conventional bioretention systems. Some of the designs include one or more plants within the unit to form a plant/soil/microbe complex for the purpose of pollutant removal. Only such specialized MTDs meet the definition of green infrastructure. Currently, MTDs approved for use as green infrastructure BMPs have a total suspended solids (TSS) removal rate of 80%. The individual certifications may be found in the table labeled Green Infrastructure (GI) MTDs posted online at: https://dep.nj.gov/stormwater/stormwater-manufactured-treatment-devices/. Take note that there are additional MTDs listed on the website, but those that are not considered GI are listed in a separate table, and this chapter does not apply to them. | N.J.A.C. 7:8 Stormwater Management Rules – Applicable Design and Performance Standards | | | | --- | --- | --- | | | Green Infrastructure | Yes | | | Stormwater Runoff Quantity | Not Allowed | | | Groundwater Recharge | Not Allowed | | % | Stormwater Runoff Quality | 80% TSS | # Introduction When selecting a GI MTD for a particular site, the peak flow rate of the Water Quality Design Storm (WQDS), the contributory drainage area and the physical size limits of the MTD installation area must be known in advance. A GI MTD must be sized in accordance with its published verification report and have a Department-issued certification letter in order to be accepted for use to meet the green infrastructure requirement specified in N.J.A.C. 7:8-5.3. A GI MTD must have a maintenance plan and must be reflected in a deed notice recorded in the county clerk's office to prevent alteration or removal.2. Table 2¶
| Area = | 0.25 ac |
|---|---|
| Slope = | 5% |
| CN Value = | 98 (100% Impervious) |
| Projected 2-year storm rainfall depth | 3.84 inches |
| Hydraulically most distant point to the inlet of MTD | 110 ft |