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8 th Canadian Waste Resource Symposium – Halifax, NS Design of an Engineered Wetland to Treat C&D Landfill Effluent April 28, 2016 Scott Kyle, P.Eng.
8th Canadian Waste ResourceSymposium – Halifax, NS
Design of an Engineered Wetland toTreat C&D Landfill Effluent
April 28, 2016
Scott Kyle, P.Eng.
• Project Background• Defining the Treatment Requirement• Design of the Treatment System• Next Steps• Q & A
2CWRS 2016
Presentation Overview
• Halifax C&D Recycling Ltd.– Established in 1995– Four facilities
• Mills Drive (Goodwood): processing and transfer*• Ross Road (Dartmouth): transfer*• Milford (East Hants): processing• Antrim: processing and disposal*
3CWRS 2016
Project Background
* Licensed to operate by HRM,75% diversion requirement
Three Corners C&DMaterial Management
Facility
4CWRS 2016
Hwy 102
Stanfield Int’l Airport
ThreeCorners Site
Westin
5CWRS 2016
ScaleHouse
SortingBuilding
Landfill(capped)
Landfill(active)
Effluent/SedimentationControl Pond
ProposedWetlandLocation
ComplianceLocation
KaulbackBrook
Three Corners C&DMaterial Management
Facility
Site Entrance
Opened 2003
• Effluent treatment an optional requirement in the Province’sC&D Disposal Site Design Guidelines (1997)
• Focus on suspended solids from exposed soil surfaces;provision of a sedimentation control pond
• Original 2003 Three Corners LF design:– Aggregate/TDA effluent collection layer at the base of each cell– Individual transmission pipe for each cell c/w valve– Effluent from the landfill cells directed to the sedimentation control pond– Gravel diffuser bed for sedimentation pond discharge– Flow through a ~100 m wooded buffer to Kaulback Brook
6CWRS 2016
Defining the Treatment Requirement
• No impacts identified through years of regular monitoring ofKaulback Brook – “the receiving water”
• Changes in LF effluent character over time; aging waste + cappingto reduce infiltration
• Tank aeration system added in 2013 to help address periodicodour issues; an effective measure
• Addition of air had one notable undesired effect:
7CWRS 2016
Defining the Treatment Requirement
Increasedmicrobialactivity
Increasedconsumption
of organicmatter
Generation ofammonia as a
byproduct
• Still no identified impacts at Kaulback Brook• NSE identifies Sedimentation Control Pond discharge as
“compliance point”• A need to reduce ammonia level + some other constituents• A practical treatment system, acknowledging…
– Remote location, genset power only– Relatively low flow
• Consideration of options….
8CWRS 2016
Defining the Treatment Requirement
Engineered Treatment Wetland
• Engineered Wetlands
– Passive treatment / limited operator intervention– No electricity– Earthworks construction– Reasonable cost– Proven, flexible– Blend into natural landscapes
9CWRS 2016
Design of the Treatment System“Treatment systems that use natural processesinvolving a) wetland vegetation, b) soils, and c)their associated microbial components to improvewater quality.”
• Design flow; landfill effluent + storm runoff– 51.5 L/min, 214 mg/L ammonia
• Atlantic Canada Wastewater Guidelines Manual (2006)– Section 9.7 provides wetland design recommendations
10CWRS 2016
Design of the Treatment System
Ce = Co*exp(-kT*t), where:Ce = effluent concentration, mg/LCo = influent concentration, mg/LkT = temperature-dependent rate constant, d-1
T = water temperature during treatment month(s), Ct = detention time of the system, days
Summer detentiontime: 9.1 daysWinter detentiontime: 9.5 days
Summer = 29 mg/L, Winter = 74 mg/L
• Flow channel dimensions selected
• Resultant length = 220 m to meet winter retention time forammonia removal
11CWRS 2016
Design of the Treatment System
400 mm LowPermeability Soil150 mm Native Soils
12CWRS 2016
Surface Flow
Sub-SurfaceFlow
Sub-SurfaceFlow
TDA = Tire DerivedAggregate
ComplianceMonitoring
PointRip-Rap
Dispersion Bed
Future Expansion
TDA
13CWRS 2016
Design of the Treatment System-in profile; Deep Section
Level Control Structure
OutFlow
InFlow
• Construction to start May/June• Construction complete by August/September• Fully operational by early fall 2016• Ongoing performance monitoring consistent with the site’s
NSE Operational Approval• Regular maintenance including periodic vegetation harvesting
14CWRS 2016
Next Steps
15CWRS 2016
Thank you!Dan Chassie - PresidentHalifax C&D Recycling Ltd.902 876 [email protected]
Scott Kyle, P.Eng. - PartnerDillon Consulting Limited902 450 4000 [email protected]
