n m - rutgers university

StormwaterTimber Creek High School

October 22, 2010

Don K

nezik

Curt

is H

elm

Rutg

ers

Coopera

tive E

xte

nsio

n

Camden County Soil

Conservation District

• What is a watershed?

• Where does precipitation go?

• Land Use / Land Cover Changes

• Point / Non-point Source Pollution

• Low-Impact Development

• Rain Gardens

Outline

What is a watershed?

An area of land that water flows across, through, or

under on its way to a stream, river, lake, ocean or other

body of water.

A watershed is like

one big bathtub...

Courtesy of Texas Watershed Stewards, Texas A&M AgriLife Extension

Gravity Recovery and Climate Experiment, University of Texas

Hydrologic Cycle

Courtesy of www.fgmorph.com

1. It can run off

Where does precipitation go?


2. It can be absorbed by plants

and used for photosynthesis

and other biological processes



3. It can infiltrate through the soil surface and percolate

downward to groundwater aquifers



4. It can evaporate



Land Use/ Land Cover

Changes


Stormwater 101

Types of Water Pollution Sources

Point Source Pollution

vs.

Nonpoint Source Pollution

Stormwater 101

What is Point Source Pollution

• Comes from a specific source, like a pipe

• Factories, industry, municipal treatment plants

• Can be monitored and controlled by a permit system (NPDES)

Stormwater 101

What is Nonpoint Source Pollution?

• Nonpoint Source (NPS) Pollution is pollution associated with stormwater or runoff

• NPS occurs when runoff collects pollutants on its way to a collection system or water body

• NPS pollution cannot be traced to a direct discharge point such as a wastewater treatment facility

Stormwater 101

Examples of NPS

• Oil & grease from cars

• Fertilizers

• Animal waste

• Grass clippings

• Septic systems

• Sewage leaks

• Household cleaning products

• Litter

• Agriculture

• Sediment

Stormwater 101

Pollutants Found in Runoff

SedimentSoil particles transported from their source

Biochemical Oxygen Demand (BOD) ● Oxygen depleting materialLeavesOrganic material

Toxics● Pesticides Herbicides Fungicides Insecticides

● Metals (naturally occurring in soil, automotive emissions/ tires) Lead Zinc Mercury

● Petroleum Hydrocarbons (automotive exhaust and fuel/oil)

DebrisLitter and illegal dumping

Nutrients● Various types of materials that become dissolved and suspended in water (commonly found in fertilizer and plant material): Nitrogen (N)

Phosphorus (P)

Bacteria/ Pathogens

Originating from:

● Pets

● Waterfowl

● Failing septic systems

Thermal StressHeated runoff, removal of streamside vegetation

Stormwater 101

Impact of Nonpoint Source Pollution

• Fish and wildlife

• Recreational water activities

• Commercial fishing

• Tourism

• Drinking water quality

Stormwater 101

Potential Sources of Pollutants Found in Residential

Areas

• Nutrients: Fertilizers and septic systems

• Pathogens: Pet waste and septic systems

• Sediment: Construction, road sand, soil erosion

• Toxic: Pesticides, household products

• Debris: Litter and illegal dumping

• Thermal: heated runoff, removal of streamside vegetation

Stormwater 101

Why are these pollutants important to control?

• Sediment reduces light penetration in stream, clogs gills of fish and aquatic invertebrates, increases filling of impoundments.

• Nutrients act as fertilizer for algae & aquatic plants which can cause highly varying dissolved oxygen levels. At low DO levels, the aquatic life has the potential to be harmed.

• BOD measures the amount of organic matter that is decomposed by microorganisms which deplete dissolved oxygen.

• Toxics can impact life and contaminate drinking water supplies.

• Bacteria/Pathogens are an indicator of possible viruses present in the system.

Stormwater 101

Connected Impervious Surfaces

• No chance for GW recharge for stream base flow

• No chance for infiltration/plant uptake for improved water quality

• Peak flow rates and volumes can be too high for stream carrying capacity

A Solution: Rain Gardens

Courtesy of City of Maplewood, MN

What is a Rain Garden?

A rain garden is a landscaped, shallow

depression that is designed to

intercept, treat, and infiltrate

stormwater at the source before it

becomes runoff. Rain Gardens are

planted with native plants of the

region and help retain pollutants that

could otherwise harm nearby

waterways.

Stormwater 101

Rain Gardens for Parking Lots

NJDEP. 2004. NJ Stormwater BMP Manual.

A rain garden is the residential version of a “bioretention system.”

Bioretention System

Rain Garden Site SelectionTimber Creek High School

October 22, 2010

Don K

nezik

Curt

is H

elm

Rutg

ers

Coopera

tive E

xte

nsio

n

Camden County Soil

Conservation District

• Shallow landscaped

depression that treats

stormwater runoff.

• Designed to merge two

important goals: aesthetics

and water quality

• Can be blended into the

landscape and made to look

natural.

• Water is directed into them

by pipes, swales, or curb

openings.

What is a Rain

Garden?

• Benefits of a Rain Garden

Video

(4.26 minutes)

Benefits

http://postit.rutgers.edu/uploads/Rain Garden Video.wmv

http://postit.rutgers.edu/uploads/Rain Garden Video.wmv

NOTE: 90% of all storm events

produce less than 1 inch of rain.

Therefore, the key to reducing

pollutant loads is to treat the

runoff associated with the first 1

inch of rain (Clayton & Schueler,

1996).

• Adsorption to soil particles− Removes dissolved metals and soluble phosphorus

• Plant uptake− Removes small amounts of nutrients

• Microbial processes− Removes organics and pathogens

• Exposure to sunlight and dryness− Removes pathogens

• Sedimentation and filtration− Removes total suspended solids, floating debris, trash, soil-bound

phosphorus, some soil-bound pathogens

• Infiltration of runoff− Provides flood control, groundwater recharge, and nutrient removal

The Science Behind

Rain Gardens

• It depends on the surface you are collecting the runoff from

• Rooftop

• Driveway

• Road

Rain Garden

Rain Garden

Rain Garden

Where do

Rain Gardens go?

• The rain garden should be at least 10 feet from the house so infiltrating water doesn’t seep into the foundation.

• Ensure adequate square footage (100 – 300 s.f.).

• Do not place the rain garden within 25 feet of a septic system.

• Do not put rain garden in places where the water already ponds or the lawn is always soggy.

• Avoid seasonably-high water tables within two feet of the rain garden depth. (e.g. 2 ½’ if rain garden is 6” deep)

• Select a flat part of the yard for easier digging as a first option.

• Avoid large tree roots.

http://clean-water.uwex.edu/pubs/raingarden/rgmanual.pdf

Where do

Rain Gardens go?

Walk the Property

Identify the following…

• Rooftop gutters and downspouts (if any)

– Do they discharge above ground?

– Are they directly connected to the road?

– Are they directly connected to the underground storm sewer?

• Existing stormwater infrastructure

– Curb/gutter for the parking lot or driveway

– Catch basins and storm sewers

• Look into the catch basins

• What is the direction of pipe flow?

– Open channel conveyance swales/ditches

– Detention basins

• Topography – flat vs. sloped

• Type of existing vegetation (if any)

Hockman Farm, Winchester, Virginia

Length

Surface Area = Length x Width

Width

Drainage

Area

Rooftop Scenario

Drainage Area

Drainage Area - Rooftop

Scenario

With no curb

Photo Credit: Rusty Schmidt

Drainage Area - Road, Driveway, or

Parking Lot Scenario

Drainage Area

Photo Credit:

Barr Engineering,

Minneapolis, MN

Drainage Area - Road, Driveway, or

Parking Lot Scenario

With a curb (curb cut needed)

Drainage Area

Saugerties Community Center, Ulster County, New York

LengthWidth

Drainage

Area

Example – Saugerties

Community Center,

Ulster County, NY

How to find the

drainage area of your

site:

10 ft 50 ft

Drainage Area =

Width x Length

10 ft x 50 ft = 500 ft2

Water should be completely drained within 24 hours

Ideal percolation rate ~ 1.5 inches/ hour

Percolation Test

Ruler

1st Hour2nd Hour3rd Hour4th Hour

Soil Test

• Sample the soil and send to the Rutgers Soil

Testing Lab for:

• Nutrient analysis/ recommendations

• pH analysis/ recommendations

• Percent sand/ silt/ clay or textural class

• Soil RibbonTest

Roll soil into a ball in hand and see how it forms

• Hard ball – Clay/Silt soil

• Soft ball – Loamy soil

• No ball – Sandy soil

But, don’t worry – clay/silt and

sandy soils can be amended to get

the preferred loamy soil texture

Gloucester County 4-H Fairgrounds

$20$50

• Optimal sand content for a rain garden is 50-70%

Size of the Rain Garden

• The size of the rain garden is a function of volume of runoff to be treated and recharged.

• Typically, a rain garden is sized to handle New Jersey’s Water Quality Design Storm: 1.25 inches of rain over two hours.

• A typical residential rain garden ranges from 100 to 300 square feet.

• Between four and eight inches deep is ideal

• Depth depends upon the soil texture

– Sandy loam: great soil for a rain garden! 4-8 inch depth is fine

– Clay: not so great soil for a rain garden. Increase the surface area and decrease the depth. Soil amendments (coarse sand and/or compost) are recommended. 3 inch depth is fine

Depth of the Rain Garden

http://clean-water.uwex.edu/pubs/raingarden/rgmanual.pdf

Rain Garden Sizing Tablefor NJ’s Water Quality Design Storm

Rain Garden Sizing TableBased on New Jersey’s Water Quality Design Storm

Drainage Area

Size of 3” Deep Rain Garden



500 ft2 200 ft2 100 ft2 75 ft2

750 ft2 300 ft2 150 ft2 112 ft2

1000 ft2 400 ft2 200 ft2 149 ft2

1500 ft2 600 ft2 300 ft2 224 ft2

2000 ft2 800 ft2 400 ft2 299 ft2

Rain Garden Sizing Tablefor NJ’s Water Quality Design

Storm

What if I don’t want to use the table… how do I determine the

size of the rain garden?

Drainage x NJ Water Quality

Area (sq ft) Design Storm (ft)

Depth (ft)

= Size of Rain

Garden (sq ft)

Drainage Area: the

impervious surface that

you’re collecting the

stormwater runoff from

NJ Water Quality Design

Storm:1.25 inches of rain

over a 2 hour period

(1.25 inches = 0.1 feet)

Depth: depends on

the soil texture

CLAY = 3 in = 0.25 ft

SANDY = 8 in = 0.67 ft

Example

So, the rain garden located on your school ground will be

approx. 700 sq ft and approx. 6 in deep.

Width

~35 ft

Length ~100 ft

Determine Drainage Area

35 ft x 100 ft = 3500 ft2

Determine volume of runoff by NJ’s

Water Quality Design Storm –

standard 1.25 in of rain per 2 hours.

Determine Depth of the Rain

Garden based on Soil Texture

6 in = 0.5 ft

3500 ft2 x 0.1 ft

0.5 ft= 700 ft21.25 in = 0.1 ft

Calculate the size of your rain garden

Timber Creek High School

Example

General Soil Amendments Amounts for a 100 sq ft Rain

Garden that is 6 Inches Deep

Soil Amendment Amount for 100 sq ft Rain Garden

Coarse Sand (Bank Run Sand) 1 cubic yard

Compost 1 cubic yard

Fertilizer Follow Soil Test Result Recommendations

Lime Follow Soil Test Result Recommendations

Gloucester County 4-H Fairgrounds

Determine Soil Amendments, if

necessary

Determine

Erosion Potential

Will the velocity and erosion of the stormwater runoff be a

problem?

• No

• Yes, erosion is possible. Address with:

• Grading

• Rocks or obstructions to slow flow

• Rocks to stabilize

• Erosion control blanket

Photo Credit: RCE of Monmouth County

Determine Rain Garden Inlet

How will the stormwater runoff enter the rain garden?

• Extended downspout/gutter

• Stone or concrete spillway

• Across lawn via a gradual slope

• Vegetated or stone-lined swales

• Diversion berm along the bottom of slope

• Paved surface

Approximate Amount of Plants Based on Future Mature Size

Size of Rain Garden Approximate Amount of Plants

100 square feet 1 Small Tree (Optional)7 Shrubs24 Herbaceous Species

200 square feet 1 Small Tree (Optional)14 Shrubs48 Herbaceous Species

Leonard Park, Morris County

Determine Plant

Quantity

The Parts of a

Rain Garden

Inlet/ Splash Pad Berm Depression Ponding Area Depression Berm

The Parts of a

Rain Garden

Types of Plants

Obligate Wetland (OBL),

Facultative Wetland (FACW)

Facultative Wetland (FACW),

Facultative (FAC),

Facultative Upland (FACU)

Lowest Zone/

Ponding Area

Middle Zone/

Depression Area

Highest Zone/

Upland Area

Facultative Upland (FACU),

Upland (UPL)

http://plants.usda.gov

Determine Plant

Quantity

http://plants.usda.gov/

Rose Mallow

Hibiscus palustris

Lowest Zone/Ponding Area Native Plants

Marsh Marigold

Caltha palustris

Determine Plant

Quantity

Middle Zone/Depression Area Native Plants

Joe Pye Weed

Eupatorium purpureum

Obedient Plant

Physostegia virginiana

Determine Plant

Quantity

Bee Balm

Monarda didyma

Highest Zone/Upland Area Native Plants

Black Eyed Susan

Rudbeckia hirta

Determine Plant

Quantity

• Sun or shade layout

• Refer to schematics (Native Plant Society of New Jersey Rain

Garden Manual)

Plant Selection

Determine Plant

Quantity

Determine Mulch

Quantity

• The benefits of mulch:

• Keeps soil moist, which allows

for percolation of rain water

• Protects plants and makes

weeding easier

• Minimizes erosion of the rain

garden soil

• Triple-shredded hardwood mulch with no dye is used in a rain garden

• Mulch should be maintained at a 3 depth in a rain garden

Amount of Mulch Required for

a Three Inch Thick Layer

Size of Rain Garden Approximate Amount of Mulch

25 square feet 0.25 cubic yard



200 square feet 2.0 cubic yards

Springfield Municipal Annex Building, Union County

Triple-Shredded Hardwood

Mulch with No Dye

Determine Mulch

Quantity

Optional Supplies

Supplies may include:

• River rock

• PVC piping

• Deer fencing

• Soaker hose

Springfield Municipal Annex Building, Union County

River Rock

PVC Pipe

Soaker

Hose

Determine Optional

Supplies

n m - rutgers university

Documents