Agenda

3 Stormwater System Mapping
A copy of the existing storm system map 1s provided in Appendix B.

2 Authority and Statement of IDDE Responsibilities

2.1 LIegal Authority

As part of the Nashua Revised Ordinances (NROs), the City adopted a Stormwater Management
ordinance in 1998 to address runoff from sites being developed or redeveloped. Since then, the
ordinance has been reviewed and revised to incorporate requirements of the 2003 MS4 Permit and
address other necessary language modifications. Through the City Charter and Nashua Revised
Ordinances, adequate legal authority 1s provided to:

e =Prohibit ilicit discharges

Figure 1-1. IDDE Investigation Procedure Framework

Inventory and Eryn yssarenc Follow-Up

eee a Ole arll

Rank Outfalls (e-| cea ae Screening

i an or an on ae |

System has
been fully

via A ee vialely eed ees Remove lllicits

poll d et =d ay alt Investigations

Investigated

Table 1-1. IDDE Program Implementation Timeline

Completion Date from Effective Date of Permit
IDDE Program Requirement

1 Year 1.5 Years | 2 Years 3 Years 7 Years 10 Years

Written IDDE Program Plan XxX

Some illicit discharges are related to the unsuitability of original infrastructure to the modern regulatory
environment. Examples of illicit discharges in this category include connected floor drains in old
buildings, as well as sanitary sewer overflows that enter the drainage system. Sump pumps legally
connected to the storm drain system may be used inappropriately, such as for the disposal of floor
washwater or old household products, in many cases due to a lack of understanding on the part of the
homeowner.

1 IDDE Program Implementation Tim e line

11 MS Pogrm

This Illicit Discharge Detection and Elimination (DDE) Plan has been developed by the City of
Nashua to address the requirements of the United States Environmental Protection Agency’s (USEPA’s)
2017 National Pollutant Discharge Elimination System (NPDES) General Permit for Stormwater
Discharges from Small Municipal Separate Storm Sewer Systems (MS4) in New Hampshire, hereafter
referred to as the “2017 New Hampshire MS4 Permit” or “MS4 Permit.”

Table 1-1. IDDE Program Implementation Timeline... eee reseenesneeseeneeneseeneeresieensessaseneeneeneenss 5
Table 6-1. Field Equipment — Dry Weather Outfall Screening and Sampling.........ccccceeee eects 14

Figure 1-1. IDDE Investigation Procedure Framework... ccc ceceeeseeee sees eeeseenesseeseseensseessneensseessneeneenenes 5

Appendix A — Nashua Revised Ordinances Article XX XI Stormwater Management

Appendix B — List of Impaired Waters Storm System Mapping

Appendix C — Outfall Inventory and Priority Ranking Matrix

Table of Contents

Illic it Disc harge Detection and Himimation Plan

11
1.2
1.3

21
2.2

3.1

3.2

5.1

5.2

6.1

6.2

7.1

Attachment A

Illicit Discharge Detection and Elimination
(IDDE) Program

Nashua, New Hampshire

Prepared By:
City of Nashua &
Hazen and Sawyer

Using the Template Prepared By:
Seacoast Stormwater Coalition &
Manchester/ Nashua Stormwater Coalition

EPA NPDES Stormwater Permit Number NHR041021
EPA NPDES Wastewater Permit Number NH010070

City of Nashua, NH
MS4 Assistance 2021-2022
Scope of Work for Engineering Services

Schedule:

Task 1: Begin no later than February 28, 2021 and end prior to May 31, 2021
Task 2: Begin no later than February 28, 2021 and end prior to May 31, 2021
Task 3: Begin no later than February 28, 2021 and end prior to May 31, 2021
Task 4: Begin no later than July 1, 2021 and end prior to May 31, 2022

Task 5: Begin no later than July 1, 2021 and end prior to May 31, 2022

Task 6: Begin no later than July 1, 2021 and end prior to May 31, 2022