HomeMy WebLinkAboutNCS000250_NCDOT Draft New Requirements_20210624DRAFT Proposed New Permit Requirements for NCDOT
1. TS4 Mapping
The permittee shall implement a program to map the TS4. At a minimum, the permittee shall:
a. Develop and maintain a statewide base map of permittee owned and operated primary highways,
secondary roads, surface waters, bridges and roadway crossings of surface waters.
b. Develop and maintain a statewide TS4 map for primary highways in urbanized areas, as defined
by having a Phase I MS4 permit or Phase II MS4 permit issued by the Department. At a
minimum, the TS4 map shall identify inlets, catch basins, conveyances, flow direction and all
major outfalls. The permittee shall:
i. Prioritize mapping to begin with the MS4 Phase I permitted areas. Phase I mapping shall
commence no later than January 1, 2024 and conclude no later than January 1, 2030.
ii. Upon completion of mapping in MS4 Phase I permitted areas, immediately commence
mapping the TS4 in MS4 Phase II permitted areas. A minimum of 20% of MS4 Phase II
permitted areas shall be mapped each year, and mapping shall be completed no later than
January 1, 2035.
iii. Following the 2040 U.S. Census, annually map a minimum of 20% of the TS4 in all new
MS4 Phase II permitted areas.
iv. Add all newly constructed TS4 outfalls and infrastructure to the TS4 map at least annually.
2. TS4 Pollution Prevention Program
The permittee shall evaluate and address stormwater pollution potential and prevent the discharge of
particulates, sediment, trash, litter and debris from specific areas of the TS4 into surface waters. At a
minimum, the permittee shall:
a. Perform and document a stormwater inspection of each major outfall concurrent with TS4
mapping. The inspection shall be documented utilizing standardized forms and protocols that
guide the inspector in assessing particulate, sediment, trash, and debris accumulation at the outfall
and in the surface waters both upstream and downstream of the outfall. Each inspection shall
include photographs, and shall identify and inventory the size, type/material, and condition of the
major outfall.
b. Perform and document a stormwater inspection concurrent with each bridge inspection. The
inspection shall be documented utilizing standardized forms and protocols that guide the
inspector in assessing particulate, sediment, trash, and debris accumulation on the bridge surface
and in the surface waters both upstream and downstream of the bridge. Each inspection shall
include photographs, and shall identify and inventory the size, type/material, and condition of all
outfalls located at the stream crossing.
c. Develop and maintain an inventory of all mapped TS4 major outfalls, inlets and catch basins, and
inspected bridge outfalls. The inventory shall include the type, size, material, inspection dates,
condition, and assigned stormwater pollution potential tier.
DRAFT Proposed New Permit Requirements for NCDOT
d. Stormwater Pollution Potential Tiers I, II and III shall be assigned as high, medium and low
stormwater pollution potential, respectively, for particulates, sediment, trash, debris, and other
stormwater pollutants. Stormwater pollution potential tiers shall be assigned based upon
standardized protocols, documented outfall and bridge stormwater inspections, illicit discharge
reports, illegal dumping reports, quantified collection of trash and debris in the drainage area,
maintenance work orders and other documented inspections, issues and concerns.
e. Develop and implement best management practices (BMPs) for Tier I outfalls to prevent the
discharge of stormwater pollutants including particulates, sediment, trash, and debris. BMPs can
and should include capture technologies; storm drain inlet grate design to minimize the entry of
trash and debris into the storm sewer system; roadway sweeping; trash, litter and debris removal;
scheduled catch basin and inlet inspections; scheduled catch basin and inlet cleaning, etc.
3. Optional Alternative TS4 Pollution Prevention Program
As an alternative to the TS4 Pollution Prevention Program permit requirements above, the permittee may
implement a task force to develop an equivalent program for evaluating and preventing the discharge of
particulates, sediment, trash and debris to surface waters from the TS4. At a minimum, the task force
shall:
a. Include permittee, Department and Division representatives.
b. Incorporate comments from the Environmental Protection Agency and the general public.
c. Fully document the equivalent alternative program including specific, measurable, achievable,
relevant, and timely (SMART) program requirements including tasks, tools, budgeting,
implementation timelines, schedules and appropriate annual reporting metrics.
d. Obtain written approval of the alternative program by the permit owner and the Department no
later than January 1, 2024. If the task force fails to meet this deadline, then the Stormwater
Inspections and Discharge Assessment permit requirements above shall immediately become
effective.
e. Once approved, the alternative program shall become an enforceable component of this permit
and shall replace the Stormwater Inspections and Discharge Assessment permit requirements
above.
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