Construction Perspectives:
Non-vegetated GI and Effective
Engineer-Contractor Communication
Presented to:
CWEA Stormwater Conference
Spring 2015 Seminar
Presented by:
April 17, 2015
Zack Knight, PE
Presentation Outline
Purpose, Goals, and Context
Case Studies: Plans and Specs vs. the Constructed Project
Infiltration beds and trenches
Porous (permeable) pavement: asphalt and pavers
Street structures and streetscaping
Stormwater structure filters, flow devices, and modifications
Parting Tips for Engineer-GI Contractor Communication
Avoiding miscommunication
Work in challenging environments
“Newbie” contractors and their subcontractors/suppliers
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Purpose and Goals
Purpose: To share construction lessons-learned and explore
the evolving nature of green infrastructure design.
Show projects up to 5 years old
Illustrate spot design areas requiring attention
Design/construction challenges and solutions
Share parting tips on effective contractor communication
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Context.. and reflection
The road less traveled: CNY
There are 2 Seasons: Winter…
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And Construction!
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“Save the Rain” Program Highlights
Onondaga County, NY
•
•
•
7,660 acres
6.1 Billion Gallons Total
Annual Combined Sewage
in Sewer Service Area
170+ Projects Completed to Date, 100,000,000 gallons of capture
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Case Study #1: Streetscape on Water Street
• Project Completed in 2012
• Runoff Reduction = 866,000 gallons annually
• Construction Cost = $986,000
• Planters,
Curb Extensions,
and Porous Pavers
• Challenges:
• Service Utilities
• Paver Layout
•
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Case Study #1: Water Street Green Gateway
•
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Case Study #1: Water Street Green Gateway
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Utility Solutions:
- Wrap Utilities in trench
- Shift GI (if possible)
- Enhanced survey (when
possible)
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Case Study #1: Water Street Green Gateway
•
Paver Layout Solutions:
- Mockups
- Addressing Curb
Irregularities before
Installation
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•
Paver Layout Solutions:
- Detailed paver
specifications, details,
and qualifications
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Case Study #2: Porous Asphalt - ROW Parking Lane
• Project Completed in 2011
• Demonstration
project for a 4’ wide porous asphalt
•
strip in public residential ROW (widening)
• Construction Cost = $66,000
• Challenges:
• Specifications vs. Supply
• Placement
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Case Study #2: Porous Asphalt - ROW Parking Lane
•
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Case Study #2: Porous Asphalt - ROW Parking Lane
Specification Solutions:
- NAPA, FHWA, or Institutional
•
- Integrate
with permeable State mixes
- Pavement design; consider geogrids
Supply Solutions:
- Work with Batch Plant ASAP
- Binder, fibers, other admixtures to
match climate and specified testing
requirements
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Case Study #2: Porous Asphalt - ROW Parking Lane
•
Placement Solutions (the quick notes):
- Contractor/Paver Pre-Pave Meeting
- Ideally track paver w/ smaller roller (8to 10-ton). 1-2 passes – it’s porous!
- Haul time/distance, ambient temp (55
F), mix temp (varies, 275-325 F), and
surface protection critical.
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Case Study #3: City Parking Lot #4
• Runoff Reduction = 2,474,000 gallons annually
•
• Construction Cost = $607,000
• Porous asphalt w/ subsurface infiltration bed
• Challenges:
•Longitudinal slope
•Subsurface Soils
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Case Study #3: City Parking Lot #4
•
Sloped finished grade Solution:
- Stepped bed, keeping connectivity
using control structures
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Case Study #3: City Parking Lot #4
Poor subgrade soils solution:
- Create a slow release system
•
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Case Study #3: City Parking Lot #4
- Slow release using PVC weirs
and orifices
•
- Stainless,
pre-eng/fab, and
hydraulic brake options
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Case Study #3: City Parking Lot #4
•
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Case Studies #4-5: Leavenworth Park and Geddes St.
Leavenworth
•
• 2,474,000 gal RR
• Cost = $607,000
• Curbside bioswale
Common Challenge: Curbing
Geddes
• 543,000 gal RR
• Cost = $279,000
• Curbside bioswale
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Case Studies #4-5: Leavenworth Park and Geddes St.
Leavenworth
•
• 2,474,000 gal RR
• Cost = $607,000
• Curbside bioswale
Common Challenge: Curbing
Geddes
• 543,000 gal RR
• Cost = $279,000
• Curbside bioswale
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Case Studies #4-5: Leavenworth Park and Geddes St.
•
Leavenworth: Curbside
Parking Curbing Solutions:
- Utilize a carriage walk
- Different options for
carriage walk at curb cuts
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Case Studies #4-5: Leavenworth Park and Geddes St.
•
Leavenworth
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Case Studies #4-5: Leavenworth Park and Geddes St.
•
Geddes St. Traffic Hazards
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Case Studies #4-5: Leavenworth Park and Geddes St.
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Geddes St. Solutions:
- Careful use of standard details
- Reinforcement adjacent to GI
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Summary of Solutions to Challenges
•
Challenges
Solutions
Service Utilities
Wrapping, Shift GI, Enhanced survey
Porous Paver Installation
Mock-Ups, Detailed specs
Porous Asphalt Specification
Tested resources, integrate with State mixes, pavement
design-consider geogrids
Porous Asphalt Supply
Batch plant coordination, mix design
Porous Asphalt Placement
Pre-pave meeting, proper equipment/logistics
Infiltration Bed Slope/Subgrade
Stepped bed, control structures, slow release
GI Curbing-Parking
Carriage walk, curb cut details
GI Curbing-Traffic
Reinforced section
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Parting Words – Contractor Communication
The most important part of ensuring a quality
constructed project is effective communication with
the contractor.
As the A/E, we are there to know and enforce the
contract fairly and firmly
Miscommunication to avoid as A/E’s
Email and paper when phone or site visit (in person) is the right
thing to do
Speculation or expressing opinion
Keep records FAT (factual, accurate, and timely) – saving for
record or an appropriate use
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Parting Words – Contractor Communication
Green infrastructure is often located in challenging
environments
Contractor site security, work hours, schedule/sequencing
Work with owner, in detail, to coordinate down time or disruption
Progress meetings with Owner and organizational resources
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Parting Words – Contractor Communication
Working with new green infrastructure contractors
Pre-qualification based on type of GI
Preconstruction meeting(s) – as many parties as possible
Supplier, vendor, and continuous progress meetings
Subcontractors
Often avoided because contract is with prime
Meet with the pavers, landscapers, and tradesman
Meet with the suppliers and their “QA-QC” personnel
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THANK YOU!
Questions?
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