Reducing Stormwater Impacts in Heavily

Developed Areas; Winooski Rain Garden Project

W i n o o s k i R a i n G a r d e n P r o j e c t

S e p t e m b e r 2 0 0 7

The Winooski Rain Garden project

was developed through a partnership between

UVM Extension Lake Champlain Sea Grant

program’s NEMO program and the city of

Winooski. A study of the Morehouse Brook

found it to be severely impaired by stormwa-

ter inputs just below Mallets Bay Avenue.

Winooski, a historic city that is heavily devel-

oped, has little area to build traditional engi-

neered stormwater facilities. In the process of

looking for an alternative way to reduce the

stormwater inputs to the Morehouse Brook,

the rain garden project was developed to dem-

onstrate to residence and business owners the

low cost and low maintenance practice to

manage their stormwater runoff.

Rain gardens originate from the

stormwater practice called bio-infiltration or

bio-retention. This practice mimics an upland

forest’s natural functions of interception, infil-

tration, chemical transformation and ground

water recharge. Rain gardens have a two fold

benefit; reducing stormwater flows and pro-

ducing clean water. This project showed the

versatility of rain gardens as a small residen-

tial garden treating roof runoff, to a large pub-

lic garden treating road runoff, to a small park

garden treating sediment laden stormwater

from a ball field, to the affects of a small gar-

den on parking lot runoff.

The project was funded by the Ver-

mont Department of Environmental Conser-

vation 319 Non-point Source Pollution Pre-

vention Grant in June of 2006. Other partners

in this project include Winooski Environ-

mental Leadership Board, University of Ver-

mont Master Gardeners Program and Ver-

mont Youth Conservation Corps.

Project Preparation

A flier was sent to all Winooski residents in

April as part of the town’s water bill mailing

advertising the rain garden project. The pro-

ject was also advertised in an article written

about the project in the Burlington Free

Press’s local section and through a live call in

program on the local cable access channel.

After receiving many emails and calls about

the project a kick off meeting was held in late

May for interested residents. Site visits to

potential garden locations were conducted by

Emma Melvin. At the same time locations for

the public gardens were reviewed by Emma

Melvin and Erik Bailey.

As part of the education component

of the project, in June, workshops were held

on the function, design and installation of rain

gardens. These workshops were open to the

public. All garden recipients were required to

attend a workshop. Master gardeners inter-

ested in the project were also encouraged to

attend. As part of the workshop, the partici-

pants installed a rain garden at the Winooski

Wastewater Treatment Plant. Twenty three

people attended the two workshops held, and

eighteen people attend the project kick-off

meeting.

North Street Rain Gardens

North Street rain gardens have about a

134,549 square feet watershed draining

into them. Twenty four percent of this

area is covered by impervious surfaces

including houses, roads and driveways.

Not all of these impervious surfaces are

asphalt or concrete, some are dirt and

gravel drives.

These rain gardens were designed slightly

oversized to compensate for the com-

pacted urban soils and somewhat larger

storms volumes (over one inch).

These rain gardens were functioning early

in April and infiltrated the spring snow

melt. They also captured water and sedi-

ment released during a water main break

on North Street above the gardens.

If the only surfaces within the watershed

draining into the rain gardens were the

impervious surfaces (~32,292 ft2) with a

precipitation of approximately 32.6 inches

(storms less than 1 inch) during the time

period the rain gardens were functioning,

these gardens have treated 1,051,750 cubic

feet of stormwater, not to mention all the

sediment captured in the gardens.

W i n o o s k i R a i n G a r d e n P r o j e c t

The Dabb’s garden was designed to capture runoff from 2/3 of the roof . There was a lower tiered garden

installed to capture any overflow from the top garden.

Installation

Garden installation started on July

29 at Jim and Carole Foster’s property, 57

Cedar Street, Winooski. Ten master garden-

ers volunteered for this garden installation.

The installation started with a short explana-

tion of a rain garden, the design and steps of

the installation. This garden treated approxi-

mately 500 square feet of the Foster’s roof.

The garden dimensions were

marked off with wooden pegs and string

prior to the installation. The master garden-

ers started by digging a one and a half foot

deep kidney shaped bowl with gently slop-

ing sides. The excess soils were used in cre-

ating a small berm on outside curve of the

planting bed. After the digging was fin-

ished, the gardeners leveled the bed and the

berm. Compost was mixed with native soils

to create the rain garden soil medium. Two

by four wood planks were laid out during

planting to minimize soil compaction.

Some of the plants in this garden

were donated by master gardeners

(approximately 3 out of the 15 planted). The

garden was mulched with approximately two

inch layer of aged mulch from the Intervale

Compost. The rain water was directed to

this garden through an extension pipe at-

tached to the rain gutter. The entrance of the

garden was lined with pebbles to protect

from erosion and to better disperse the wa-

ter.

The next garden was installed on

August 5, 2006 at Karen McCreas’ property

on 103 North Street Winooski. This garden

treated approximately the same size roof but

the rain water was directed to the garden by

a sloped drip line armored with cobble. This

garden was also installed by master gardener

volunteers.

The public gardens at Landry Park

were installed August 7-11 by the Vermont

Youth Conservation Corps crew. The town

of Winooski excavated most of the gardens

and created the curb cut for the entrance of

the gardens prior to installation. The town

also transported to the site all the gravel used

for the garden entrances and the walkway

from the baseball field. The compost and

mulch was delivered to the site by Intervale

Compost.

On August 7, the first day at

Landry Park with the VYCC crew, Andrew

Gordon from the University of Vermont’s

Across the Fence TV program, came and

filmed the installation and interviewed Eric

Bailey from the city of Winooski, Sally

Dean, the master gardener involved in the

project and Jim Foster, a garden recipient.

On that same day, a reporter and photogra-

pher from the Burlington Free Press inter-

viewed the VYCC crew members and the

project coordinator Emma Melvin. This

article appeared in the Burlington Free Press

the following day August 8. The Across the

Fence show aired early October.

Each of the larger gardens at

Landry Park was installed in a day. Each

was installed with a gravel entrance to dissi-

pate some of the erosive energy of the

stormwater as it enters the garden. An as-

phalt speed bump was also installed below

the curb cuts on the garden located along

North Street. These speed bumps were in-

stalled to help direct the stormwater in the

gardens. The gravel entrances were de-

signed to also allow for some water storage

and sedimentation for any thing being car-

ried in the stormwater. Many of the plants

used in these gardens were donated by mas-

ter gardeners and others.

Two rototillers, one loaned from

the Winooski Parks Department and one

rented from Essex Equipment were used to

un-compact soils in all the of the gardens.

Due to the high use and the common nature

of urban soils, they were of poor quality and

highly compacted. Replacement soils were

purchased from Intervale Compost. These

soils were used in the upper garden located

along North Street.

The next garden installed was for

the Michael Dabb's’ property at 217 Mallets

Bay Avenue. It was a unique garden given

that it crossed underneath the front fence and

was tiered. The upper tier was the main

garden and the lower tier was for overflow.

The upper tier had an earthen berm but the

lower tier had reinforced wooden wall.

Rain Garden Sign to be posted at the public rain

gardens.

R e s i d e n t i a l R a i n G a r d e n s a n d M a s t e r G a r d e n e r s

This project pur-

pose was to dem-

onstrate the uses of

rain gardens as a

viable tool to man-

age stormwater in

an ultra urban envi-

ronment. By part-

nering with the

Master Gardeners

program, this project was able to reach master gardeners

throughout the state and within Chittenden County. Master gar-

deners helped the home owners choose the proper plants for

their garden and how to maintain a healthy garden. They also

generously donated many of the plants used within the rain gar-

dens installed in this project. This highly respected and active

group planted the seed of rain gardens in their local communi-

ties. Stemming from this partnership a rain garden workshop

was presented at the Annual Association of Professional Horti-

culturist meeting and rain gardens and the Winooski project was

featured on the cover page of the Living Section of the Burling-

ton Free Press in July 2007. As part of this projects partnership

master gardener program has been working with Lake Cham-

plain Sea Grant to develop a plant list suitable for Vermont rain

gardens.

Special thanks to Nancy Hullet, Sally Dean, Marc Conpanion,

Tage Lilja and Ann Pearce.

The rain water was directed to the

garden through an extension pipe connecting

to the down spout. A small rock pile was

created at the end of the extension pipe to

dissipate the flow into the garden. Approxi-

mately eight volunteers helped install this

garden.

The last garden installed in the fall

was at the Nocito property at 4 Pine Grove

Terrace. This garden infiltrated one fourth

of the roof and was adjacent to the back

deck. The garden was adjacent to the gutter

and required little directing. This garden

comprised mostly of bushes, most interest-

ingly blueberry bushes and some herbaceous

flowering plants.

Visits were made to the installed

gardens to assess for any problems and en-

sure proper functioning in the fall and the

following spring and summer.

Two rain garden tours were con-

ducted in the fall of 2006 for interested mas-

ter gardeners, state employees, university

faculty and students. 17 people attended the

tours. Two more tours were given in April

2007 for the master gardeners and a Ver-

mont Technical College horticultural class.

An presentation was made to the

Winooski City planning and development

review boards about the project and rain

gardens encouraging them to consider rain

gardens and Low Impact development as a

solution to manage the towns stormwater.

An educational how- to poster was

created for municipalities and others inter-

ested. An informative brochure was created

about the project and was distributed at the

Vermont Farm Show and is currently dis-

played at the State Extension office in Col-

chester. The Across the Fence show and

the brochure is also available now on the

Lake Champlain Sea Grant webpage. The

project was also spotlight in a presentation

made to the New England Conservation

Districts at their annual meeting in Febru-

ary. A workshop on incorporating rain

gardens and other low impact development

strategies focused the Winooski Rain Gar-

den Project was presented at the Town Of-

ficials Education Conference spring of

2007.

Educational signs were designed

by the Maja Smith with the LCBP Wayside

Exhibit Program. This fall the signs will be

posted at the public gardens explaining the

stormwater impact on streams and how rain

gardens function and reduce these impacts.

Identical signs will be posted at rain gardens

installed by Otter Creek, Poultney Met-

towee, and Rutland.

Maintenance

All gardens were visited early

spring to see if any damage was incurred

over the winter. All gardens were function-

ing properly and were infiltrating spring

snow melt.

Plants were added to the North

Street gardens. The North Street gardens

were impacted by a water main break above

the gardens on North Street that washed in

large amounts of sediment. This sediment

covered the lower two gardens about 2 1/2

inches deep. The upper garden received less

sediment with only a thin layer of sediment

over sections of the garden. This sediment

was removed early enough by Emma Melvin

and the volunteer master Sally Dean to incur

no damage to the plants. Sediment depos-

ited into the garden is the largest mainte-

nance issue with the North Street gardens.

Few of the drive ways located in the water-

shed draining into the rain garden are gravel

or dirt. It is quite apparent that these drive-

ways are contributing enormous amounts of

sediment entering into the gardens. The

driveways can be identified by the type of

gravel that appears within the garden. Large

stones were added to the entrance to stabi-

lize the entrance. Much of the smaller

gravel was transported into the garden after

the larger storms and the water main break.

The gravel and sediment built up at the en-

trance of the gardens were removed as part

of the route weeding. Mulch was stockpiled

at the city wastewater treatment plant and

was used to mulch all the public gardens.

W i n o o s k i R a i n G a r d e n P r o j e c t

Sediment and gravels washed into the rain garden entrances at North Street. This is removed as part of

the season maintenance.

Garden edging was added to the gardens to

reduce the weeds within the garden. Sally

Dean has adopted the North Street garden

and has helped maintain these garden this

summer with Emma Melvin. She will con-

tinue this maintenance in the following

years.

All plants that were planted at these

gardens survived this year and will be moni-

tored next year.

The other Landry Park gardens

were damaged during park construction. No

maintenance was completed on these gar-

dens due to the continued construction and

inability of the city securely say that these

gardens would be maintained and restored

after construction.

The gardens located at the waste-

water treatment plant were re-mulched at the

beginning of the season and weeded through

the season. Most plants in these gardens

came back this season.

Stormwater Reduction

Some stream flow monitoring was

completed after the garden installations.

Morehouse Brook is piped under ground for

much of its length. It is first piped under

ground at the industrial park near the head

waters and is piped under North Street and

Landry Park. The flow measurements were

made at the point the stream reappeared

from underground just lower left corner of

Landry Park and where it day-lights again at

Mallets Bay Avenue. Upstream measure-

ments were made but were hard to compare

to the downstream measurements due to the

industrial park’s stormwater detention pond

in which the stream drains into prior to it

being piped underground. With the means

available no flow measurements could be

made directly upstream of the North Street

rain gardens to assess the actual decrease in

stormwater flow entering the stream. Esti-

mates were made of decreased stormwater

for each rain garden for the functioning pe-

riod of the garden by calculating the rain fall

and multiplying it by the drainage area of the

rain garden (Figure 2). The precipitation

data used for this calculation was taken from

the NOAA National Weather Forecast Of-

fice webpage for Burlington (Figure 1). The

time period used does not include periods

during the winter when the gardens were

filled with snow. For the residential gar-

dens, the total rain fall was used since resi-

dence noted that their rain gardens never

filled. For the Public gardens only storms 1

inch or less were used in the calculations.

Though rain gardens did infiltrate snow melt

this was not included in the calculations.

Figure 2. Winooski Rain Gardens

Infiltrated Stormwater

Garden Drainage

area

Infiltrated

Rain

Foster 500 ft2 19,495 ft3

Dabb 850ft2 26,928 ft3

McCrea 500 ft2 18,020 ft3

Nocito ft2 7,920 ft3

North Street 32,292 ft2 1,051,750 ft3

Wastewater

Treatment 600 23,394 ft3

Figure 1. Precipitation After Rain

Gardens Installed

Gardens

Installed Date

Inches

of Rain

Rain

Events

Above 1

Inch

Aug-07 1.46 b

Jul-07 6.29 2

Jun-07 2.26 b

May-07 1.95 b

Apr-07 3.79 1.27

Mar-07

Dec-07 3.84 1.74

Nov-07 2.62 b

Nocito Oct-07 6.25 1.96

Dabbs Sep-06 3.22 b

McCreas &

Landry Park Aug-06 4.36 1.5

Fosters &

Waste Water

Treatment

Plant Jul-07 2.95 b

Total

Rain 38.99

Nocito garden has an assortment of shrubs including

summer sweet and blueberry bushes.

S u r v e y R e s u l t s a n d C o m m e n t s 1) Have you seen pooling in your garden?

McCreas: Yes, I have seen pooling, but only in the middle of a

very heavy rain storm (remember, I also funnel water from the

back roof into the garden, AND we built it a tad larger than was

originally anticipated).

Foster: No standing water at all.

Nocito: There has not been any pooling in our garden.

2) Have all the plants survived?

McCreas: I lost one plant over last winter.

Foster: All survived

Nocito: All of our plants survived beautifully

3) Are you satisfied with the gardens performance?

McCreas: The garden is wonderful - it also supported a large

gaggle of bird-planted sunflowers all summer. The best display of

sunflowers I have EVER had.

Foster: Absolutely

Nocito: We love our garden! It performs great!

4) Have you talk to other people about rain gardens?

McCreas: Yes, I talk to people about the rain garden ...... and

thanks for the Free Press referral!

Foster: Constantly, a couple who I have talked to has put one in

or have plans too. People who talked to ask more questions about

putting one.

Nocito: Yes we have talked with other people about our garden.

5) Do people ask you about your rain garden?

McCreas: Thanks to the Free Press article, lots of people ask me

about my rain garden.

Foster: No neighbors this year but neighbors on each side asked

last summer.

Nocito: People cannot see ours unless they are in our backyard,

but typically if I bring it up they ask more about it.

Winooski Rain Garden Locations

Public Garden Locations:

Landry Park-

3 gardens on North Street along Park fence

1 gardens within park adjacent to bleachers

1 garden within park adjacent to baseball field dugout

Winooski Wastewater Treatment Plant-

2 gardens adjacent to parking lot

Private Garden Locations:

217 Mallets Bay Avenue

57 Cedar Street

103 North Street

4 Pine Grove Terrace

This project was funded by a Vermont Agency of Natural

Resources, Department of Conservation Non-point Source Pollution

Control Grant, and by the CSREES USDA New England Regional

Water Quality Project, award number USDA 00-51130-9775.

W i n o o s k i R a i n G a r d e n P r o j e c t ,

p r o t e c t i n g o u r w a t e r w a y s t h r o u g h g a r d e n i n g

Picutres taken during the Winooski Rain Garden

Porject.

University of Vermont

63 Carrigan Drive

Burlington, VT 05405

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