EPA Technical Assistance Grant - Beaufort SC Northwest Quadrant

Block by Block Green Infrastructure
Northwest Quadrant Conceptual Design

City of Beaufort

Beaufort’s Block by Block Green Infrastructure


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

Under Natural
Conditions Runoff is ....But increases After
Limited.... Development

5

Green Infrastructure - Multiple Benefits

 Water quality  Cost savings
 Flood and  Community identity
hydromodification  Recreational
control greenspace
 Rainwater capture and  Reduced urban heat
use island effect
 Increased groundwater  Wildlife habitat
recharge and baseflow  Enhanced property
 Improved air quality values
 Reduced energy  Carbon sequestering
consumption  Aesthetic benefits

Multiple Benefits

Category Indicator
Reduced Stormwater Volume
Environmental Reduced Peak Flow Rate
Reduced Pollutant Loading
Increased Groundwater Recharge
Reduced Energy Use and Heat Island Effect
Reduced Particulate Matter
Increased Carbon Sequestration
Improved Quality of Life and Aesthetics
Social
Increased Recreational Opportunities
Job Creation
Reduced Infrastructure Costs
Economic
Reduced Pumping Costs
Increased or Stabilized Property Values

Effects of Water Pollution

Photo courtesy of NRCS

BMP Functions

Hydrologic
controls Removal processes

Evapotranspiration
or flow attenuation

Biotransformation/
Storage/detention

phytoremediation
Bioaccumulation

volatilization)
photolysis;
Other (e.g.,
Infiltration

Filtration

Sorption
Settling
Structural BMPs
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 Schematic
Runoff
Vegetation on Surface

Media

Underdrain System

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

Bioretention Areas
• Soil Media Depth
Where are pollutants removed? TSS
TP
Temp
TN
Pathogens
Metals
Oil & Grease

Bioretention Areas

www.bae.ncsu.edu/stormwater

Integrating into Landscape


Parking Lots

Port City
Java, Market

Parking Lots


Bioretention Areas
+ 4 Hours
+14 Hours

Bioretention Areas

 Mulch and Vegetation
 Drought tolerant vegetation
 Periodic inundation
 Native species
 Consider size and appearance at maturity

Bioretention Variations

 Bioswales

Bioretention Variations

 Transportation Corridor
 Right-of-way

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 Guide for Design of Pavement Structures
AASHTO
 In situ soil strength
(1993)
•
 Environmental elements to the Guide for Design of
AASHTO Supplement
 Bedding and Structures (1998)
Pavement reservoir layer design
• AASHTO Flexible Pavement Method

Permeable Pavement

 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

6 inches pervious concrete

Washed no 57 stone (Min 6”)

Permeable Pavement

6 in

6-9 in

12-18 in

Permeable Pavement

Grid Pavers
Sand
PICP with gravel fill
Washed No. 57 Stone

Interlocking Concrete Pavers
Pea Gravel
Washed No. 57 Stone

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



US Marine Corps Air Station Golf Professionals Club
Laurel Bay

116

Beaufort Northwest Quadrant 802

Project Location

Burton
Beaufort
Beaufort
280

21
281

170

802

Port Royal
Legend
Par is
Project Location Shell Point
M ale co

Northwest Quadrant Boundary
n

City of Beaufort Limits
Highway
Marine Corps Recruit Depot
Major Road
Parris Island
Railroads (Local)
Lake/Pond/Stream/River
City of Beaufort
Swamp/Marsh 0 0.5 1 2
Miles South Carolina
Cities
Project Location

Beaufort’s Block by Block Green Infrastructure BOUNDARY ST


WILMINGTO N ST
UNION ST
BA
GG
ET CONGRES S ST
T ST

BLADEN ST

CHURCH ST
GREENE ST
RIBAU T RD

Northwest

MONSON ST

NEWCASTLE ST
D

WASHINGTON ST
MARS H R

HAMAR ST
Quadrant

HARRINGTON ST
Beaufort DUKE ST

ADVENTURE ST
BLADEN LN

PRINCE ST

ELTON LN
PILOT ST

KING ST
KING ST
EUHAW ST

GLEBE ST
HEYWARD ST
WAIGHT ST

NORTH ST NORTH ST

T
YS CRAVEN ST
BA

Historic
ST
Downtown
SIM
MS Beaufort River Beaufort
T RD
PO
DE

Legend
City of Beaufort
Streets 0 200 400 800
Feet South Carolina
Northwest Quadrant Boundary
Northwest Quadrant

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

Project Criteria

s
ment

nsect

t
enefi
prove

Techn ration of
of T ra

ts
ood B

fi
Bene
lity
age Im

ology
n
r Q ua

bor h
ra tio

nst

la ry
Demo

Neigh
Dr ain

Wate

Integ

Ancil
Candidate Project/Transects
Section 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 Street
Connection of Duke and Princeton ○    ● ●
Duke Street from Bladen to Pilot Street ● ● ●   ●
Candidate Improvements
Bump Outs for Tree Space ● ●   ● ●
Vegetated Curb Extensions ● ●   ● ●
Residential on-lot Permeable Pavement ● ● ●  ● ●

20
15
BAGGETT ST

HAMAR ST
UNION ST

20
GREENE ST

20
20

25
20

WASHINGTON ST

20

20
DUKE ST

ADVENTURE ST
15

Legend
Storm Sewers
PRINCE ST
Streets

BLADEN ST
Duke Street Catchment
Proposed Vegetated
15

Basin Catchment 20
Beaufort
Parcels Infiltration Basin
Elementary
PILOT ST

Elevation, ft
5 KING ST School KING ST

10
GLEBE ST

15
25
20
25

25
25

25 25
25

City of Beaufort
0 50 100 200
Feet South Carolina
Project Contributing Areas

Prince Street and Hamar Street

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


• Water Volume and Quality
Treatment
• Community Park Space
• Aesthetic Improvement

23

22

16
17
PRINCE ST

Diversion Structure Inlet & Monitoring Point

Water

19
16

Green Green 18

20 21
Ponding Surface Storage
22
Infrastructure Infrastructure Width Length Depth Area Volume
HAMAR ST

23

Practice Practice Location (ft) (ft) (ft) (sq ft) (cu ft)
Vegetated Legend
Catch Basins
infiltration Open Space
Diversion Structure
Inlet & Monitoring Point
Basin Parcel
Streets
Storm Sewers
125 125 2.0 15,700 20,880
Proposed Inlet Line
Parcels
Top Footprint
24

Banks - 2:1 Sideslope
Banks - Steps
Bottom Footprint

City of Beaufort
0 15 30 60
Feet South Carolina
Implementation Areas

Duke Street From Bladen To Hamar

• Permeable Pavement and
Bioretention
• Streetscape Enhancement
• Aesthetic Improvement

Duke Street From Bladen To Hamar

• Water Volume and Quality
Treatment
• Enhanced Parking Areas
• Reduce Localized
Flooding

Duke Street From Bladen To Hamar WAS HING TON ST

HAMAR ST

ADVENTURE ST
DUKE ST

BLADEN ST
Green
Infrastructure PRINCE ST
Legend
Catch Basins
Practice Width Length Surface Area Water Storage
Practice Sewers
Storm Location (ft) (ft) (sq ft) Volume (cu ft)
Streets
Bioretention
Bioretention
Right-of-way 200 8
0 50 100
840 6,717
City of Beaufort 9,404
South Carolina
PermeablePavement
Permeable Pavement Right-of-way Feet 8 Available Implementation Area
1680 13,434 4,030

Duke Street From Bladen To Hamar WASHINGTON ST

HAMAR ST

ADVENTURE ST
DUKE ST

BLADEN ST
Green
Infrastructure
Legend
Practice Width Length Surface Area Water Storage
PRINCE ST
Practice Basins
Catch Location (ft) (ft) (sq ft) Volume (cu ft)
Storm Sewers
Bioretention Right-of-way 8 182of Beaufort
1,453 2,034
±
Streets
City
Bioretention 0 45 90 180
South Carolina
Permeable Pavement
Permeable Pavement Right-of-way Feet
8 363 2,906 872

Operations and Maintenance
Task Frequency Maintenance notes
Monitor 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 If drought conditions exist, watering after the initial year might be
months; sporadically after required.
establishment
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, Check for sediment accumulation to ensure that flow into the
then monthly during the rainy retention area is as designed. Remove any accumulated sediment.
season
Outlet inspection Once after first rain of the season, Check for erosion at the outlet and remove any accumulated mulch or
then monthly during the rainy sediment.
season
Miscellaneous upkeep 12 times/year Tasks include trash collection, plant health, spot weeding, and
removing mulch from the overflow device.

Operations and Maintenance
Permeable pavement operations and maintenance considerations
Forebay cleanout As needed, typical 5 – 10 Check for sediment accumulation to ensure that
years flow into the retention area is as designed.
Remove any accumulated sediment.
Invasive species/tree Semi-annual Within the first year, 10% of plants can die.
control Survival rates increase with time.
Bank mowing and Monthly or as needed Frequency depends on the location, plant
stabilization selection and desired aesthetic appeal.
Outlet inspection and Monthly and after storms Check for erosion at the outlet and remove any
cleanout greater than 2 inches accumulated mulch or sediment.
Trash removal As needed Remove accumulated debris throughout the
area.
Rodent & mosquito As needed Inspect for signs of vector control issues. Proper
management eradication measures should be used.

Stormwater wetland operations and maintenance considerations
Impervious to Pervious Once after first rain of Check for sediment and debris accumulation to
interface the season, then monthly ensure that flow onto the permeable pavement
during the rainy season 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 1-2 times per year (and Fill materials will need to be replaced after each
(applies to pervious after any vac truck sweeping and as needed to keep voids with the
pavers only) sweeping) paver surface.
Miscellaneous upkeep 4 times per year or as Tasks include trash collection, sweeping, and
needed for aesthetics spot weeding.

Cost Estimate
Item
No Description Quantity Unit Unit Cost Total
Preparation
1 Traffic Control 15 Day $1,000.00 $15,000
2 Temporary Construction Fence 500 LF $2.50 $1,250
3 Silt Fence 500 LF $3.00 $1,500
Site Preparation
4 Excavation and Removal 775 CY $45.00 $34,875
5 Clearing and Grubbing 15,700 SF $0.75 $11,775
Vegetated Infiltration Basin
6 Fine Grading 15,700 SF $0.72 $11,304
7 Inlet Diversion Structure 1 LS $15,000 $15,000
8 Vegetation 15,700 SF $4.00 $62,800
Construction Subtotal $153,504
9 Bond (5% of subtotal) $7,675
10 Mobilization (10% of subtotal) $15,350
11 Construction contingency (20% of subtotal) $30,701
Construction Total $207,230
12 Design (40% of Construction Total) $82,892
Total Cost $290,123

Cost Estimate
Item No Description Quantity Unit Unit Cost Total
Preparation
1 Traffic Control 15 day $1,000.00 $15,000
2 Temporary Construction Fence 545 LF $2.50 $1,363
3 Silt Fence 545 LF $3.00 $1,635
Site Preparation
4 Curb and Gutter Removal 545 LF $3.30 $1,799
5 Excavation and Removal 296 CY $45.00 $13,320
Traditional Bioretention
7 Fine Grading 1,453 SF $0.72 $1,046
8 Soil Media 162 CY $40.00 $6,480
9 Filter Layer (sand and No. 8 stone) 18 CY $45.00 $810
10 Vegetation 1,453 SF $4.00 $5,812
11 Mulch 14 CY $55.00 $770
12 Curb and Gutter 278 LF $22.00 $6,116
Permeable Pavement
13 Curb and Gutter 363 LF $22.00 $7,986
14 Permeable Pavement 2906 SF $12.00 $34,872
15 Structural Layer (washed no 57 or no 2 stone) 54 CY $50.00 $2,700
16 Concrete Transition Strip 363 LF $4.00 $1,452
17 Utility Conflicts 1 LS $10,000.00 $10,000
Construction Subtotal $111,160
21 Bond (5% of subtotal) $5,558
22 Mobilization (10% of subtotal) $11,116
23 Construction contingency (20% of subtotal) $22,232
Construction Total $150,066
24 Design (40% of Construction Total) $60,026
Total Cost $210,093

Annual Maintenance Costs

Routine
Green Infrastructure Area Unit Cost Maintenance
Practice (ft2) (per ft2) (monthly to 2 years)
Bioretention 1,453 $2.28 $3,312.84
Permeable pavement 2,906 $0.67 $1,947.02
Vegetated Infiltration Basin 15,700 $1.91 $29,987.00

EPA Technical Assistance Grant - Beaufort SC Northwest Quadrant

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Editor's Notes