EPA Technical Assistance Grant - Beaufort SC Northwest Quadrant

City of Beaufort

Block by Block Green InfrastructureNorthwest Quadrant Conceptual Design

Beaufort’s Block by Block Green InfrastructureNorthwest Quadrant Conceptual Design


Preservation guidelines • Maintaining the traditional character of the block; • Maintaining the informal nature of the streets, lanes,

and gardens where they exist; • Maintaining the soft edges found along neighborhood

streets; and• Encouraging informal gardens throughout the

neighborhood.

Neighborhood Strategic Plan • Encouraging the use of rain barrels and greywater

recycling; • Supporting community gardens; and• Identifying future pocket park locations.

What is Green Infrastructure? Stormwater management strategy that uses natural hydrologic features to manage water and provide environmental and community benefits.


How do we make this… function more like this?

Green Infrastructure

5

Under Natural Conditions Runoff is

Limited........But increases

After Development

What is Green Infrastructure? Stormwater management strategy that uses natural hydrologic features to manage water and provide environmental and community benefits.


How do we make this… function more like this?

Cost savings Community identity Recreational

greenspace Reduced urban heat

island effect Wildlife habitat Enhanced property

values Carbon sequestering Aesthetic benefits

Green Infrastructure - Multiple Benefits

Water quality Flood and

hydromodification control

Rainwater capture and use

Increased groundwater recharge and baseflow

Improved air quality Reduced energy

consumption

Multiple Benefits

Category Indicator

Environmental

Reduced Stormwater Volume

Reduced Peak Flow Rate

Reduced Pollutant Loading

Increased Groundwater Recharge

Reduced Energy Use and Heat Island Effect

Reduced Particulate Matter

Increased Carbon Sequestration

SocialImproved Quality of Life and Aesthetics

Increased Recreational Opportunities

Economic

Job Creation

Reduced Infrastructure Costs

Reduced Pumping Costs

Increased or Stabilized Property Values

Economic Benefits

Effects of Water Pollution

Photo courtesy of NRCS

BMP Functions

Structural BMPs

Hydrologic controls Removal processes

Storage/detention or flow attenuation

Infiltration

Evapotranspiration

Settling

Filtration

Sorption

Bioaccumulation

Biotransformation/ phytoremediation

Other (e.g., photolysis; volatilization)

Bioretention + (+) o o + o + + (o)

Permeable pavement + (+) – – + – – – –

Infiltration basin + + (o) o + o + + (o)

Cisterns/rain barrels + – – – – – – – –Note: ( ) optional function; + major function; o secondary function; – insignificant function

BMP Design

Bioretention Bioswales Planter Boxes

Permeable Pavement Green Roofs Water Harvesting

Cisterns Rain Barrels

Sand Filters Vegetated Swales Vegetated Filter Strips

Bioretention Areas

Bioretention Schematic

Media

Underdrain System

Vegetation on SurfaceRunoff

Bioretention Areas

Pollutant removal functions Sedimentation (temporary)

Trash, TSS, Phosphorus Microbial Processes

Nitrogen, Pathogens Chemical Processes

Metals, Phosphorus Exposure to Sunlight & Dryness

Pathogens, Oil & Grease

Where are pollutants removed? TSS

TP

Temp

TN

Pathogens

Metals

Oil & Grease

Bioretention Areas

• Soil Media Depth

www.bae.ncsu.edu/stormwater

Bioretention Areas


Integrating into Landscape


Parking Lots

Port City Java, Market Street


Parking Lots

+ 4 Hours

+14 Hours

Bioretention Areas

Bioretention Areas

Mulch and Vegetation Drought tolerant vegetation Periodic inundation Native species

Consider size and appearance at maturity

Bioretention Variations

Bioswales

Transportation Corridor Right-of-way

Bioretention Variations

Permeable Pavement

Allows for rainfall infiltration

Low traffic surfaces (driveways, parking lots, walk ways)

Provides peak flow mitigation, volume storage, and some water quality improvement

Permeable Pavements

Permeable Interlocking Concrete Pavers (PICP)

Concrete Grid Pavers (CGP)

Pervious (Porous) Pavements (PC & PA)

Plastic Reinforcing Grids (PG)

Permeable Pavement

Store/Treat the design storm volume within base and sub-base reservoirs

• d = V / A × n– d = Gravel Layer Depth (ft)– V = Water Quality Volume– A = Surface Area (square ft)– n = Porosity (0.3 to 0.4)

Structural Design Total traffic In situ soil strength Environmental elements Bedding and reservoir layer design

Permeable Pavement

• AASHTO Guide for Design of Pavement Structures (1993)

• AASHTO Supplement to the Guide for Design of Pavement Structures (1998)

• AASHTO Flexible Pavement Method

These systems should be installed by a qualified professional

• The only exception is very small backyard patios where BMP failure will not be hazardous to human health

• A list of professionals qualified in permeable paver installation is available through the Interlocking Concrete Pavement Institute (ICPI) – www.icpi.org

• More information on pervious concrete is available through the Carolina Ready Mixed Concrete Association (CRMCA) – www.crmca.com

Permeable Pavement

http://www.icpi.org/

Permeable Pavement

6 inches pervious concrete

Washed no 57 stone (Min 6”)

Permeable Pavement

6 in

6-9 in

12-18 in

Permeable Pavement

Washed No. 57 StoneWashed No. 57 Stone

Pea GravelPea Gravel

Interlocking Concrete PaversInterlocking Concrete Pavers

Washed No. 57 StoneWashed No. 57 Stone

SandSand

Grid PaversGrid Pavers

PICP with gravel fill

Permeable Pavement

Permeable Pavement

6 in

6-9 in

12-18 in

Permeable Pavement

Permeable Pavement

Vegetated Infiltration Basin

Photo credit: Jill Bicknell, Santa Clara Valley Urban Runoff Program.

Stormwater Wetlands

Reduce Nutrients Slow Flow of Water

Stormwater Wetlands


A Diverse System of Herbaceous Plants tends to limit mosquito population

Human Introduction of Gambousia affinis NOT recommended

Stormwater Wetlands

Multi-Benefit Use


Burton

Beaufort

Shell Point

Port Royal

Laurel Bay

Parris Island

21

170

281

802

280

116

802

Male

con

Par

is

Beaufort

US Marine Corps Air StationUS Marine Corps Air Station

Marine Corps Recruit DepotMarine Corps Recruit Depot

Golf Professionals ClubGolf Professionals Club

0 1 20.5Miles

City of BeaufortSouth Carolina

Project Location

Legend

Project Location

Northwest Quadrant Boundary

City of Beaufort Limits

Highway

Major Road

Railroads (Local)

Lake/Pond/Stream/River

Swamp/Marsh

Cities

Beaufort Northwest QuadrantProject Location


BAY ST

DUKE ST

PRINCE ST

GREENE ST

RIB

AU

T R

D

KING ST

BOUNDARY ST

CH

UR

CH

ST

NORTH STH

AM

AR

ST

BLA

DE

N S

T

NE

WC

AS

TLE

ST

MO

NS

ON

ST

WASHINGTON ST

SIMMS ST

HA

RR

ING

TON

ST

WIL

MIN

GT

ON

ST

WA

IGH

T S

T

AD

VE

NT

UR

E S

T

MA

RS

H R

D

ME

RIT

TA A

VE

CONGRESS ST

EU

HA

W S

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UN

ION

ST

HE

YW

AR

D S

T

BAGGETT ST

GLE

BE

ST

PIL

OT

ST

DEPOT RD

CRAVEN ST

ELTON LN

BLADEN LN

KING ST

NORTH ST

0 400 800200Feet


Northwest Quadrant

Legend

Streets

Northwest Quadrant Boundary

Beaufort River

HistoricDowntownBeaufort

NorthwestQuadrantBeaufort

Charrette Process

Work session with director and staff Site selection and preliminary concept plans Presentations to staff and officials Final concept plans and report Final presentation

Implementation

Regulating Plan T3 Neighborhood General T4 Urban Neighborhood and Neighborhood Center T5 Urban Center/Corridor

Localized Improvements Public Right of Way and Block Level Solutions

Transects

Integration of Green Infrastructure techniques into the planning and development process

Consistent, predictable costs and performance, and replicable results

Adaptable to local conditions Ancillary benefits and values

Aesthetics, identity, energy…..

Localized Improvements

Correct drainage issues Improve streetscape and reduce maintenance Create community value Demonstrate progress Planned and Constructed incrementally

DraftProject Criteria

Drai

nage

Impr

ovem

ent

Wat

er Q

ualit

y

Inte

grati

on o

f Tra

nsec

ts

Dem

onst

ratio

n of

Te

chno

logy

Nei

ghbo

rhoo

d Be

nefit

Anci

llary

Ben

efits

Candidate Project/TransectsSection 8 Housing Church and Washington Streets ○ ○ ○ Private Lot between Prince and Hamar ● ● ○ ● ●Glebe Street Extension ● ● ● Stormwater Dry Pond Hamar and Washington ○ ○ ● ●Green Street along Pilot from Prince to North StreetConnection of Duke and Princeton ○ ● ●Duke Street from Bladen to Pilot Street ● ● ● ●Candidate ImprovementsBump Outs for Tree Space ● ● ● ●Vegetated Curb Extensions ● ● ● ●Residential on-lot Permeable Pavement ● ● ● ● ●

T3 – Neighborhood

T4 – Neighborhood Center

T5 – Urban Corridor/Center

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25

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2025

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25

20

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15

HA

MA

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DUKE ST

PRINCE ST

GREENE ST

BLA

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UN

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ST

KING ST

BAGGETT ST

WASHINGTON ST

PIL

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GLE

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ST

KING ST

Legend

Storm Sewers

Streets

Duke Street Catchment

Basin Catchment

Parcels

Elevation, ft5

10

15

20

25

0 100 20050Feet


Project Contributing Areas

Proposed VegetatedInfiltration BasinBeaufort

ElementarySchool

• Vegetated Infiltration Basin• Open Community Park Space• Large watershed

Prince Street and Hamar Street


• Water Volume and Quality Treatment

• Community Park Space• Aesthetic Improvement


Diversion Structure Inlet & Monitoring Point

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24

19

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232216

HA

MA

R S

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PRINCE ST

Legend

Catch Basins

Diversion Structure

Inlet & Monitoring Point

Streets

Storm Sewers

Proposed Inlet Line

Parcels

Top Footprint

Banks - 2:1 Sideslope

Banks - Steps

Bottom Footprint

0 30 6015Feet


Implementation Areas

Green Infrastructure Practice


Practice LocationWidth

(ft)Length

(ft)

Ponding Depth

(ft)

Surface Area (sq ft)

Water Storage Volume (cu ft)

Vegetated infiltration Basin

Open Space Parcel 125 125 2.0 15,700 20,880

Duke Street From Bladen To Hamar

• Permeable Pavement and Bioretention

• Streetscape Enhancement• Aesthetic Improvement

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25

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2025

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HA

MA

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DUKE ST

PRINCE ST

GREENE ST

BLA

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UN

ION

ST

KING ST

BAGGETT ST

WASHINGTON ST

PIL

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GLE

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ST

KING ST

Legend

Storm Sewers

Streets

Duke Street Catchment

Basin Catchment

Parcels

Elevation, ft5

10

15

20

25

0 100 20050Feet


Project Contributing Areas

Proposed VegetatedInfiltration BasinBeaufort

ElementarySchool


• Water Volume and Quality Treatment

• Enhanced Parking Areas• Reduce Localized

Flooding


DUKE ST

PRINCE ST

HA

MA

R S

T

BL

AD

EN

ST

WASHINGTON ST

AD

VE

NT

UR

E S

T

0 100 20050Feet


Available Implementation Area

Legend

Catch Basins

Storm Sewers

Streets

Bioretention

Permeable Pavement



Practice Location

Width (ft)

Length (ft)

Surface Area(sq ft)


Bioretention Right-of-way 8 840 6,717 9,404Permeable Pavement Right-of-way 8 1680 13,434 4,030


DUKE ST

PRINCE ST

HA

MA

R S

T

BL

AD

EN

ST

WASHINGTON ST

AD

VE

NT

UR

E S

T

±0 90 18045Feet


1.95 inch Event Area

Legend

Catch Basins

Storm Sewers

Streets

Bioretention

Permeable Pavement



Practice Location

Width (ft)

Length (ft)

Surface Area(sq ft)


Bioretention Right-of-way 8 182 1,453 2,034

Permeable Pavement Right-of-way 8 363 2,906 872

Operations and Maintenance

Task Frequency Maintenance notesMonitor infiltration and drainage 1 time/year Inspect drainage time (12–24 hours). Might have to determine

infiltration rate (every 2–3 years). Turning over or replacing the media (top 2–3 inches) might be necessary to improve infiltration (at least 0.5 in/hr).

Pruning 1–2 times/year Nutrients in runoff often cause bioretention vegetation to flourish.

Mowing 2–12 times/year Frequency depends on the location, plant selection and desired aesthetic appeal.

Mulching 1–2 times/ year Recommend maintaining 1”–3” uniform mulch layer.

Mulch removal 1 time/2–3 years Mulch accumulation reduces available water storage volume. Removal of mulch also increases surface infiltration rate of fill soil.

Watering 1 time/2–3 days for first 1–2 months; sporadically after establishment

If drought conditions exist, watering after the initial year might be required.

Fertilization 1 time initially One-time spot fertilization for first year vegetation.

Remove and replace dead plants 1 time/year Within the first year, 10% of plants can die. Survival rates increase with time.

Inlet inspection Once after first rain of the season, then monthly during the rainy season

Check for sediment accumulation to ensure that flow into the retention area is as designed. Remove any accumulated sediment.

Outlet inspection Once after first rain of the season, then monthly during the rainy season

Check for erosion at the outlet and remove any accumulated mulch or sediment.

Miscellaneous upkeep 12 times/year Tasks include trash collection, plant health, spot weeding, and removing mulch from the overflow device.

Task Frequency Maintenance notesImpervious to Pervious interface

Once after first rain of the season, then monthly during the rainy season

Check for sediment and debris accumulation to ensure that flow onto the permeable pavement is not restricted. Remove any accumulated sediment, vegetative debris, or trash. Stabilize any exposed soil.

Vacuum street sweeper Twice per year as needed Portions of pavement should be swept with a vacuum street sweeper at least twice per year or as needed to maintain infiltration rates.

Replace fill materials(applies to pervious pavers only)

1-2 times per year (and after any vac truck sweeping)

Fill materials will need to be replaced after each sweeping and as needed to keep voids with the paver surface.

Miscellaneous upkeep 4 times per year or as needed for aesthetics

Tasks include trash collection, sweeping, and spot weeding.

Task Frequency Maintenance notesForebay cleanout As needed, typical 5 – 10

yearsCheck for sediment accumulation to ensure that flow into the retention area is as designed. Remove any accumulated sediment.

Invasive species/tree control

Semi-annual Within the first year, 10% of plants can die. Survival rates increase with time.

Bank mowing and stabilization

Monthly or as needed Frequency depends on the location, plant selection and desired aesthetic appeal.

Outlet inspection and cleanout

Monthly and after storms greater than 2 inches

Check for erosion at the outlet and remove any accumulated mulch or sediment.

Trash removal As needed Remove accumulated debris throughout the area.

Rodent & mosquito management

As needed Inspect for signs of vector control issues. Proper eradication measures should be used.

Permeable pavement operations and maintenance considerations

Stormwater wetland operations and maintenance considerations

Operations and Maintenance

Cost Estimate

Item No Description Quantity Unit Unit Cost Total

Preparation 1 Traffic Control 15 Day $1,000.00 $15,0002 Temporary Construction Fence 500 LF $2.50 $1,2503 Silt Fence 500 LF $3.00 $1,500 Site Preparation 4 Excavation and Removal 775 CY $45.00 $34,8755 Clearing and Grubbing 15,700 SF $0.75 $11,775 Vegetated Infiltration Basin 6 Fine Grading 15,700 SF $0.72 $11,3047 Inlet Diversion Structure 1 LS $15,000 $15,0008 Vegetation 15,700 SF $4.00 $62,800

Construction Subtotal $153,5049 Bond (5% of subtotal) $7,675

10 Mobilization (10% of subtotal) $15,35011 Construction contingency (20% of subtotal) $30,701

Construction Total $207,23012 Design (40% of Construction Total) $82,892

Total Cost $290,123

Cost EstimateItem No Description Quantity Unit Unit Cost Total

Preparation 1 Traffic Control 15 day $1,000.00 $15,0002 Temporary Construction Fence 545 LF $2.50 $1,3633 Silt Fence 545 LF $3.00 $1,635 Site Preparation 4 Curb and Gutter Removal 545 LF $3.30 $1,7995 Excavation and Removal 296 CY $45.00 $13,320 Traditional Bioretention 7 Fine Grading 1,453 SF $0.72 $1,0468 Soil Media 162 CY $40.00 $6,4809 Filter Layer (sand and No. 8 stone) 18 CY $45.00 $810

10 Vegetation 1,453 SF $4.00 $5,81211 Mulch 14 CY $55.00 $77012 Curb and Gutter 278 LF $22.00 $6,116 Permeable Pavement

13 Curb and Gutter 363 LF $22.00 $7,98614 Permeable Pavement 2906 SF $12.00 $34,87215 Structural Layer (washed no 57 or no 2 stone) 54 CY $50.00 $2,70016 Concrete Transition Strip 363 LF $4.00 $1,452

17 Utility Conflicts 1 LS $10,000.00 $10,000Construction Subtotal $111,160

21 Bond (5% of subtotal) $5,55822 Mobilization (10% of subtotal) $11,11623 Construction contingency (20% of subtotal) $22,232

Construction Total $150,06624 Design (40% of Construction Total) $60,026

Total Cost $210,093


Area (ft2)

Unit Cost(per ft2)

Routine Maintenance(monthly to 2 years)

Bioretention 1,453 $2.28 $3,312.84Permeable pavement 2,906 $0.67 $1,947.02Vegetated Infiltration Basin 15,700 $1.91 $29,987.00

Annual Maintenance Costs

Typical Maintenance

Questions?

EPA Technical Assistance Grant - Beaufort SC Northwest Quadrant

Design

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