fBackground: In July of 2012, the City was awarded a $100,000 Technical Assistance Grant from the EPA. As part of that award, in November a team of stormwater and environmental engineers, and planners came to Beaufort for three days. Working with members of the city’s planning and public works departments, they identified two specific projects that could improve stormwater management in the Northwest Quadrant, and incorporate these practices into overall street and block design. This will be a presentation of the final designs, and the design process. This is the final presentation of the design, given by Jason Wright of TetraTech at City Hall on April 3, 2013.
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EPA Technical Assistance Grant - Beaufort SC Northwest Quadrant
1. Block by Block Green Infrastructure
Northwest Quadrant Conceptual Design
City of Beaufort
2. Beaufort’s Block by Block Green Infrastructure
Northwest Quadrant Conceptual Design
3. Beaufort’s Block by Block Green Infrastructure
Northwest 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.
4. Beaufort’s Block by Block Green Infrastructure
Northwest Quadrant Conceptual Design
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?
5. Green Infrastructure
Under Natural
Conditions Runoff is ....But increases After
Limited.... Development
5
6. Beaufort’s Block by Block Green Infrastructure
Northwest Quadrant Conceptual Design
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?
7. 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
8. 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
27. Bioretention Areas
Mulch and Vegetation
Drought tolerant vegetation
Periodic inundation
Native species
Consider size and appearance at maturity
33. 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
34. 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
57. Stormwater Wetlands
A Diverse System of
Herbaceous Plants tends
to limit mosquito
population
Human Introduction of
Gambousia affinis NOT
recommended
www.bae.ncsu.edu/stormwater
59. Beaufort’s Block by Block Green Infrastructure
Northwest Quadrant Conceptual Design
60. Beaufort’s Block by Block Green Infrastructure
Northwest Quadrant Conceptual Design
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
61. Beaufort’s Block by Block Green Infrastructure BOUNDARY ST
Northwest Quadrant Conceptual Design
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
62. 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
63. 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
64. 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…..
65. Localized Improvements
Correct drainage issues
Improve streetscape and reduce maintenance
Create community value
Demonstrate progress
Planned and Constructed incrementally
66.
67. 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 ● ● ● ● ●
75. 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
76. Prince Street and Hamar Street
• Vegetated Infiltration Basin
• Open Community Park Space
• Large watershed
77. Prince Street and Hamar Street
• Water Volume and Quality
Treatment
• Community Park Space
• Aesthetic Improvement
78. 23
Prince Street and Hamar Street
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
79. Duke Street From Bladen To Hamar
• Permeable Pavement and
Bioretention
• Streetscape Enhancement
• Aesthetic Improvement
80. Duke Street From Bladen To Hamar
• Permeable Pavement and
Bioretention
• Streetscape Enhancement
• Aesthetic Improvement
81. 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
82. Duke Street From Bladen To Hamar
• Water Volume and Quality
Treatment
• Enhanced Parking Areas
• Reduce Localized
Flooding
83. Duke Street From Bladen To Hamar WAS HING TON ST
HAMAR ST
ADVENTURE ST
DUKE ST
BLADEN ST
Green
Infrastructure PRINCE ST
Legend
Green Infrastructure
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
84. Duke Street From Bladen To Hamar WASHINGTON ST
HAMAR ST
ADVENTURE ST
DUKE ST
BLADEN ST
Green
Infrastructure
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
85. Duke Street From Bladen To Hamar WASHINGTON ST
HAMAR ST
ADVENTURE ST
DUKE ST
BLADEN ST
Green
Infrastructure
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
86. 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.
87. Operations and Maintenance
Permeable pavement operations and maintenance considerations
Task Frequency Maintenance notes
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
Task Frequency Maintenance notes
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.
88. 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
89. 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
90. 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
Beaufort River impaired for fecal coliform and dissolved oxygen (eutrophication from nutrients)Impaired for aquatic life, good for recreation (for now)
Beaufort River impaired for fecal coliform and dissolved oxygen (eutrophication from nutrients)Impaired for aquatic life, good for recreation (for now)
Bioretention BMPs are small-scale, shallow, vegetated, depressed areas with a soil (often engineered soil)media and plant-based filtration device that removes pollutants through a variety of physical, biological,and chemical treatment processes
36 acres. Does not include the drainage area for the Department of Social Services.
Provide treatment for the runoff generated by the 1.22 inch event
1.5 acres.
Utilizing all of the area available for implementation (6,717 square feet of bioretention and 13,434 square feet of permeable pavement) will provide treatment for the runoff generated by the 5.97 inch event (approximately a 5 year event), substantially more than is required by the current design storm.