nutt pond watershed restoration

NUTT POND

WATERSHED

RESTORATION CITY OF MANCHESTER

STORMWATER MANAGEMENT

PROGRAM

NUTT POND

Nutt Pond is one of 6 urban ponds

located in Manchester, NH

NH DES & the City monitor these urban

ponds with help from the Volunteer Lake

Assessment Program (VLAP)

The City of Manchester started the Nutt

Pond study in 2005 through the

Supplemental Environmental Project

Program as part of the on-going CSO

separation efforts.

NUTT POND AREA OVERVIEW

Location: Driving Park Road, off of South Willow Street in south Manchester.

NUTT POND WATERSHED

Watershed Area: 635

Acres

Watershed is broken

into 4 subwatersheds

based on inlet locations.

One natural inlet

(Tannery Brook) &

three storm drain inlets

Highly Urbanized

Land Use: Commercial

& High Density

Residential

Approximately 60%

Impervious

WATERSHED RESTORATION

PLAN In 2002, Nutt Pond was placed on the NH 305(b)/303(d) list based on

chlorophyll-a levels, limiting primary contact recreation. It was also listed for

Non-Native Aquatic Plants.

In subsequent years it was also listed based for phosphorus, chlorides, pH and

dissolved oxygen levels.

WATERSHED RESTORATION

PLAN

The City prepared a Watershed Restoration Plan to determine existing

pollutant loading, select BMPs and identify pollutant removals that would

help reach long term water quality goals.

Problem: It was determined that approximately 125 lbs/yr of TP and 47 tons

/ year of TSS enter Nutt Pond via Stormwater

WATERSHED RESTORATION

PLAN

It was estimated that the average phosphorus levels in Nutt Pond were 0.028 mg/L

It was determined that a water quality goal of 0.015 mg/L should be the target for

long-term “in-pond” phosphorus concentration in order to reduce chlorophyll-a levels.

This would require a decrease in total annual phosphorus loading from 161 pounds

(124 lbs stormwater) to 86 pounds. A reduction of 75 lbs/yr.

WATERSHED RESTORATION

PLAN

Solution:

Decrease TSS & TP Loading = Decreased Nutt Pond chlorophyll-a

levels

Select BMPs to target TSS & TP removal

BMP SELECTION

Example of the BMP Ranking Process:

Select BMPs that will fit on a

site and allow maintenance to be performed.

Rank the BMPs based on the information below.

Cost of the BMP.

The highest removal efficiency for the contaminant that you are trying to remove.

The least cost per pound for the contaminant that you are trying to remove.

Select the BMPs that are implementable, within the dollar amount allotted for the project and that rank the highest based on the above information.

BMP SELECTION

NO SINGLE BMP

WILL SOLVE

ALL YOUR

PROBLEMS.

YOU MAY

NEED TO PAIR

UP BMPs TO

GET THE

DESIRED

RESULTS.

THIS WOULD ALSO

INCLUDE

PUBLIC

EDUCATION

AND OTHER

NON-

STRUCTURAL

BMPS

SAND REDUCTION PROGRAM

SAND REDUCTION PROGRAM

WATERSHED RESTORATION

PLAN

2005 – City of Manchester awarded 319s grant funding to

complete study and Phase 1 BMPs

2006 – Completion of Watershed Restoration Plan.

Summer 2006 – Completion of the East Inlet BMP.

Fall 2006 – Completion of the North & South Inlet

Retrofits.

Fall 2006 – Completion of the West Bank Stabilization BMP

Summer 2007 – Completion of the South Inlet BMP

Summer 2010 – Completion of the Woodgate Court

Drainage & Stabilization BMPs

2011 - City of Manchester awarded 319s grant funding to

complete study and Phase 2 BMPs

NUTT POND INLET

IMPROVEMENTS SITES

SITE 1 – NORTH INLET

SITE 2 – SOUTH INLET

SITE 3 – EAST INLET

SITE 4 – SOUTH INLET (HENRY’S)

SITE 5 – WEST BANK STABILIZATION

SITE 6 – WOODGATE COURT

NORTH INLET SITE 1

NORTH INLET SITE 1

SOUTH INLET SITE 2

EAST INLET SITE 3

EAST INLET SITE 3

EAST INLET SITE 3

EAST INLET SITE 3

EAST INLET SITE 3

SOUTH INLET (HENRY’S) SITE 4

SOUTH INLET (HENRY’S) SITE 4

SOUTH INLET (HENRY’S) SITE 4

SOUTH INLET (HENRY’S) SITE 4

WESTBANK STABILIZATION SITE 5

WOODGATE COURT SITE 6

10’ DIA. DEEP SUMP DMH

UPSTREAM HEADWALL

ROCK CROSS VANE

CHANNEL

ADDITIONAL DRAINAGE

ADDITIONAL DRAINAGE

OUTLET GRATE

PROJECT COSTS

Project (Phase) Total Cost Grant Funding

Nutt Pond Phase 1 Grant $599,000 $60,000

Woodgate Court

(construction only) $366,000 $0

Nutt Pond Phase 2 Grant

(anticipated) $350,000 $174,000

Totals $1,131,500 $234,000

WEST INLET PROPOSED SITE 7

WEST INLET PROPOSED SITE 7

Source: UNH Stormwater Center Website: http://www.unh.edu/unhsc/

EAST INLET PROPOSED SITE 8

EAST INLET PROPOSED SITE 8

Source: UNH Stormwater Center Website: http://www.unh.edu/unhsc/

WATERSHED PLAN SUCCESS

Estimated BMP removals to date:

East Inlet ~ 185 cubic yards of sediment

South Inlet ~ 145 cubic yards of sediment

Woodgate Court Channel (East Inlet) ~ 4,500 cubic yards of sediment

Woodgate Court BMPs (East Inlet) ~ 6 cubic yards of sediment

Since 2008, approximately 4,836 cubic yards removed (~ 1,200 Cy/Yr)

WATERSHED PLAN SUCCESS

Phosphorus Levels:

WATERSHED PLAN SUCCESS

Chlorophyll a levels:

MORE INFORMATION

Websites

Stormwater http://www.manchesternh.gov/CityGov/dpw/EPD/stormwater/home.html

SEPP (Supplemental Environmental Projects Program) http://www.manchesternh.gov/CityGov/DPW/EPD/SEPP/Home.html

Contact Information:

Robert Robinson, P.E. Environmental Permits Coordinator City of Manchester Department of Highways Environmental Protection Division 300 Winston Street Manchester, NH 03103 Ph: 603-624-6513 Fax: 603-628-6234 Cell: 603-235-6630 E-mail: rrobinson@manchesternh.gov

Benjamin Lundsted, P.E. Environmental Engineer Comprehensive Environmental, Inc. 21 Depot Street Merrimack, NH 03054 Ph: 603-424-8444 Fax: 603-424-8441 Cell: 800-725-2550 E-mail: blundsted@ceiengineers.com