how will the new stormwater rules affect you?

A State’s Perspective of the

EPA’s Effl uent Limitations Guidelines

40 CFR Part 450

Jeffrey B. Shaver, PE, CPESC

HOW WILL THE NEW STORMWATER RULES AFFECT

YOU?

AASHTO Subcommittee On DesignJuly 27, 2010

EFFLUENT LIMITATIONS GUIDELINESApplicability

Discharges associated with construction activity required to obtain NPDES permit coverage

New Source Performance Standards (NSPS) apply to all new sourcesReflecting The Best Available Demonstrated Control TechnologyConstruction Activity including clearing, grading, and excavation

that disturbs 5 or more acres Less than 5 acres if part of a larger common plan that will ultimately

disturb 5 or more acres.Effective February 1, 2010

All other sources covered underBest Practicable Technology Currently Available (BPT)Best Available Technology Economically Achievable (BAT)Best Conventional Pollutant Control Technology (BCT)Effective February 1, 2010

EFFLUENT LIMITATIONS GUIDELINESThe new requirements must be incorporated into any

new general or individual permits issued after February 1, 2010TN CGP is being reissued Fall 2010

Implementation DatesFebruary 1, 2010 – Non-numeric effluent limitations

NSPS, BPT, BAT, BCTAugust 1, 2011 – Numeric effluent limitation for

construction sites that disturb 20 or more acresNSPS, BAT

February 2, 2014 – Numeric effluent limitation for construction sites that disturb 10 or more acresNSPS, BAT

Non-numeric Effluent LimitationsErosion and Sediment Controls

Control stormwater volume and velocity within the site to minimize soil erosion

Control storm discharges, including both peak flow rates and total stormwater volume, to minimize downstream channel and stream bank erosion

Minimize the amount of soil exposed during construction activity

Minimize the disturbance of steep slopes


Minimize sediment discharges from the site. The design, installation and maintenance of erosion and sediment controls must address factors such as the amount, frequency, intensity and duration of precipitation, the nature of resulting stormwater runoff, and soil characteristics, including the range of soil particle sizes expected to be present on the site


Provide and maintain natural buffers around surface waters, direct stormwater to vegetated areas to increase sediment removal and maximize stormwater infiltration, unless infeasible

Minimize soil compaction and unless infeasible, preserve topsoil

Non-numeric Effluent LimitationsSoil Stabilization

Stabilization of disturbed areas must, at a minimum, be initiated immediately whenever any clearing, grading, excavating or other earth disturbing activities have permanently ceased on any portion of the site, or temporarily ceased on any portion of the site and will not resume for a period exceeding 14 calendar days. Stabilization must be completed within a period of time determined by the permitting authority. In arid, semiarid, and drought-stricken areas where initiating vegetative stabilization measures immediately is infeasible, alternative stabilization measures must be employed as specified by the permitting authority.

Non-numeric Effluent LimitationsDewatering

Discharges from dewatering activities, including discharges from dewatering of trenches and excavations, are prohibited unless managed by appropriate controls.

Non-numeric Effluent LimitationsPollution Prevention Measures

Design, install, implement, and maintain effective pollution prevention measures to minimize the discharge of pollutants. At a minimum, such measures must be designed, installed, implemented and maintained to:Minimize the discharge of pollutants from equipment and vehicle

washing, wheel wash water, and other wash waters. Wash waters must be treated in a sediment basin or alternative control that provides equivalent or better treatment prior to discharge

Minimize the exposure of building materials, building products, construction wastes, trash, landscape materials, fertilizers, pesticides, herbicides, detergents, sanitary waste and other materials present on the site to precipitation and to stormwater

Minimize the discharge of pollutants from spills and leaks and implement chemical spill and leak prevention and response procedures.

Non-numeric Effluent LimitationsProhibited Discharges

The following discharges are prohibited:Wastewater from washout of concrete, unless managed by

an appropriate controlWastewater from washout and cleanout of stucco, paint,

form release oils, curing compounds and other construction materials

Fuels, oils, or other pollutants used in vehicle and equipment operation and maintenance

Soaps or solvents used in vehicle and equipment washing.

Surface OutletsWhen discharging from basins and impoundments,

utilize outlet structures that withdraw water from the surface, unless infeasible.

Numeric Effluent LimitationsAverage turbidity of any discharge for any day

must not exceed 280 NTU daily maximumConduct monitoring consistent with

requirements established by the permitting authority. Each sample must be analyzed for turbidity in accordance with methods specified by the permitting authority.

If stormwater discharges in any day occur as a result of a storm event in that same day that is larger than the local 2-year, 24-hour storm, the effluent limitation does not apply for that day.

TURBIDITY MONITORING At least three grab samples, representative of a discharge,

shall be collected for the duration of each discharge event. The first grab sample should be taken during the first 30

minutes of the discharge. If the collection of a grab sample during the first 30 minutes

is impracticable, a grab sample can be taken during the first hour of the discharge.

The minimum time period between representative grab samples shall be 30 minutes.

Permittees may sample the turbidity in their discharges multiple times over the course of a day and the average of all measurements should not exceed the average daily value limitation.

TURBIDITY MONITORING Samples and measurements taken in compliance with the

monitoring requirements specified herein shall be representative of the volume and nature of the monitored discharge, and shall be taken after treatment and: Prior to mixing with uncontaminated storm water runoff or the

receiving stream Prior to effluent leaving the construction site boundary

The numeric limitation applies to all discharges from construction sites. However, diffuse stormwater, such as non-channelized flow through a silt fence or other perimeter control that infiltrates into a vegetated area, and does not then discharge to surface waters, would not generally require sampling.

Sampling should be conducted, at a minimum, during normal business hours at a project. The working day can generally be considered to be between the hours of 6 a.m. and 6 p.m., or when workers are normally present on the construction site.

TURBIDITY MONITORING When a linear construction site has two or more outfalls

that must be sampled and the permittee reasonably believes outfalls discharge substantially identical effluents, the permittee may monitor the effluent of one of such outfalls. The permittee shall select a representative outfall

conveying stormwater runoff from the largest disturbed area for that discharge event.

The permittee shall report on the monitoring report that the quantitative data also applies to the substantially identical outfall(s).

TURBIDITY MONITORING The permittee shall evaluate the results obtained from

sampling and monitoring to determine whether the facility complies with effluent limitations.

If the results of stormwater runoff monitoring demonstrate that the site has exceeded the limitation, the permittee must review its storm water pollution prevention plan, make any modifications or additions to the plan which would assist in reducing effluent concentrations to less than the monitoring limitations, including a timetable for implementation.

SR 437, BEDFORD COUNTY

TOTAL RAINFALL/

WATERSHED ACREAGE

AVERAGE DAILY NTU

Trace 44

Enhanced Rock Check Dam

Photo & Data Provided By: Civil and Environmental Consultants, Inc.

SR 95, ROANE/ANDERSON COUNTIES


TOTAL RAINFALL/

WATERSHED ACREAGE

AVERAGE DAILY NTU

0.6 inches/4 acres 625




TOTAL RAINFALL/

WATERSHED ACREAGE

AVERAGE DAILY NTU



TOTAL RAINFALL/

WATERSHED ACREAGE

AVERAGE DAILY NTU



3 Rock Check Dams1 Enhanced Rock Check Dam



3 Rock Check Dams1 Enhanced Rock Check Dam

TOTAL RAINFALL/

WATERSHED ACREAGE

AVERAGE DAILY NTU



TOTAL RAINFALL/

WATERSHED ACREAGE

AVERAGE DAILY NTU

0.1 inch/7 acres 103

SR 101, CUMBERLAND COUNTY

Silt Fence With Wire BackingSediment Tubes (Wattles)


TOTAL RAINFALL/

WATERSHED ACREAGE

AVERAGE DAILY NTU

0.1 inch/3.5 acres 57

SR 101, CUMBERLAND COUNTY

Silt FenceSediment Tubes (Wattles)


TOTAL RAINFALL/

WATERSHED ACREAGE

AVERAGE DAILY NTU

0.1 inch/4 acres 237

SR 101, CUMBERLAND COUNTYSilt Fence


EFFECTS ON EPSC TOOLBOXResearchModify Existing BMPs, Add New BMPsModify Manuals and Standard DrawingsTrain Staff

COMBINING EXISTING

BMPS

POLYACRYLAMIDE

DESIGNING SYSTEMS

QUESTIONS

how will the new stormwater rules affect you?

Documents