MS4: POLLUTANT REDUCTION PLANNING FOR

IMPAIRED WATERWAYS

May 17, 2017

Pollutant Reduction Plan (PRP)

A plan developed to identify and then reduce a baseline amount of a

specific pollutant by some preset percentage (using various facilities,

BMP’s and programs).

Total Maximum Daily Load (TMDL)

The maximum amount of a specific pollutant that a waterbody can

assimilate and still meet WQ standards. Baseline has been pre-

established.

How is a TMDL Different from a PRP?

Chesapeake Bay Plan is a TMDL Plan (pollution diet)

Adopted in December 29, 2010 - Largest TMDL ever developed by EPA

Plan is to be completed by 2025, currently at the halfway point

(where 60% goals are to be met, Phase III Watershed Implementation Plan

(WIP’s) in progress) – Monday June 5th – Public Kickoff Meeting

6 States (and District of Columbia) participate in the TMDL Plan (by way of

WIP’s)

PRP’s become a tool to help shape and ensure successes for the

obligations of a WIP and the Bay TMDL

Chesapeake Bay TMDL

TMDL Limits are set at 185.9 million pounds of Nitrogen, 12.5 million

pounds phosphorus and 6.45 billion pounds of sediment (per year).

Overall watershed reductions for these limits are set at 25%, 24% and

20% respectively.

PA reduction goals are;

10% (Total Suspended Sediment)

5% (Total Nitrogen)

3% (Total Phosphorus)

Note:

In PA Permittees are encouraged to achieve the 10% sediment

reduction as this is expected to then result in the 5% and 3% reductions

Chesapeake Bay TMDL - Limits

How do I know if I have a local TMDL?

http://files.dep.state.pa.us/Water/BPNPSM/StormwaterManagement/MunicipalStormwater/Municipal_MS4_Requirements_Table.pdf

PRP Pollutant Reduction Plan – Impaired Waters

• If Impairment is sediment (Siltation) only, a 10% reduction is required.

• If Impairment is Nutrients only (or excessive algal growth, organic

enrichment/low DO), then a 5% Phosphorus reduction is required

• If Impairment is due to both sediment and nutrients, then PRP must

reduce sediment (10%) and Phosphorus (5%).

What does listed “impairment” mean for PRP?

Appendices (from Municipal Requirements Table)

Utilizing “Parsing” in PRP

Parsing for PRP – Optional process whereby land area is “removed” from the

loading calculations (if shown to not be of concern)

Note: Parsing for TMDL plans is a slightly different topic.

Why would you do this for PRP?

Reduces the pollutant loading and therefore reduces obligation for

reduction

Why wouldn’t you do this?

BMP’s in parsed areas cannot be included in PRP reduction calculations

Utilizing “Parsing” in PRP

Examples where Parsing may be appropriate;

Area of land is covered under an existing NPDES site (Industrial

Stormwater Discharge for example)

PennDOT (or Turnpike) rights-of-way

CAFO (already covered under NPDES)

Land area where stormwater does not contribute to MS4

Parsing can be “undone”…submit a “modified PRP” (same public hearing

applies)

Can I use existing programs or BMP’s to offset required reduction for

existing pollutant loading?

…but not as a direct “deduct”

Existing practices or BMP’s can ONLY be accounted for in PRP as

reduction in existing baseline.

What about existing BMP’s and Programs?

Example – Estimated loading of sediment is 1,000 pounds (per year) per

your PRP. To meet 10% reduction (or 100 pounds), PRP can propose that

an existing street sweeping program removes 50 pounds per year.

You cannot claim in your PRP that you meet half the annual goal by street

sweeping;

WHY???

1. Offset must come from baseline…PRP can claim 50 pounds per year

less as the starting point…950 pounds. Therefore 10% means now that

you need to only reduce by 95 pounds, not 100.

2. Side note: PA DEP does not allow street

sweeping to be the only BMP proposed to

reduce pollutants.

What about existing BMP’s and Programs?

Items needed to claim existing (structural) BMP credit in PRP;

• A detailed description of the BMP;

• Latitude and longitude coordinates for the BMP;

• Location of the BMP on the storm sewershed map;

• The permit number, if any, that authorized installation of the BMP;

• Calculations demonstrating the pollutant reductions achieved by the BMP;

• The date the BMP was installed and a statement that the BMP continues to

serve the function(s) it was designed for; and

• The operation and maintenance (O&M) activities and O&M frequencies

associated with the BMP.

(Source: PA DEP)

What about existing BMP’s and Programs?

Section A – Public Participation

Complete PRP must be available for someone to review

Advertise for public review (no less than 45 days prior to submission to

PA DEP) – provide copy of ad for PRP

Accept written comments (30 days from notice)

Address each noted concern and any changes made

What is required to be in a PRP?

Section B – Map

Develop map to show land uses, and/or impervious coverage

waterways

stormsewer shed to each outfall to impaired waterway or waterways noted in

Appendix D & E

Parsed areas

MS4 boundaries

Outfalls

Municipal Boundaries

What is required to be in a PRP?

Section C – Pollutants of Concern

• Note the pollutants being considered as part of the PRP (either by

Chesapeake Bay TMDL or by impaired waters (Siltation, Nutrients or both)

What is required to be in a PRP?

Section D – Determine Existing Loading for Pollutants of Concern

Calculating Pollutant Loads - Several Methods Available:

• (easiest) Simplified Approach

Obtain county specific loading rates

Determine impervious and non-impervious land coverage

(within UA area)

Apply rates to areas and calculate the loading

What is required to be in a PRP?

Simplified Approach for PRP’s

MapShed

Other Methods to Calculate PRP Loading

• Wiki Watershed

Other Methods to Calculate PRP Loading

Notes:

• User friendly to locate watershed and develop model

• Allows HUC 8/10 & 12 scale watershed analysis

• Web based platform (no proprietary software)

• Allows analysis on manually drawn drainage areas

(EPA) SWMM

Notes:

• Requires more extensive effort to build model

• Requires calibration

• Some loading calculations and efficiencies are flow volume based

Other Methods to Calculate PRP Loading

Section E – Select BMP’s to Achieve Minimum Required Reductions in

Pollutant Loading

Develop a “top down” calculation of how you will reduce pollutants;

- What new BMP’s or programs will community engage in to reduce loading

- Focus on “low hanging fruit” first (street sweeping)

- Other practices should look for most cost effective means (most ROI per

dollar spent)

• Avoid boutique BMP’s…low reduction, higher cost

• Stream restoration best one out there for reductions per cost

• Look for retrofits (larger facilities handling urban DA)

• Must be able to complete projects within 5 years (permit cycle)

• Use Effectiveness values provided by PA DEP.

• Use Expert Panel Papers to assist in calculating allowable reductions

- Continue reductions until full value is reached

What is required to be in a PRP?

Section F – Identify Funding Mechanisms

Feasibility of plan is evaluated by PA DEP (don’t promise the world)

• Look for partners, sponsors

• Look to outside limited term funding programs (grant or loan)

• Does not have to be guaranteed, but need to have backup plan if

funding option fails

What is required to be in a PRP?

Section G – Identify Responsible Parties for Operation and

Maintenance of BMP’s

• The party(ies) responsible for ongoing O&M;

• The activities involved with O&M for each BMP; and

• The frequency at which O&M activities will occur.

Annual Report will be mechanism to ensure activities are performed per

O&M

What is required to be in a PRP?

• Signing on for a 5 year program...spend time to make sure the plan fits

community

• Don’t delay and expect to “throw” one together 46 days prior to

submission

• Engage community, look for opportunities to partner (not just for

funding but for buy-in)

• Don’t be afraid to ask questions…lots of questions (even the

professionals don’t know everything)

Summary / Take Away

P. Eric Mains, PE

Sr. Water Resource Engineer

pmains@gfnet.com