bob hedin, hedin environmental, “two passive treatment systems that are regional community...

Two Passive Treatment Systems that are Community Assets

Bob HedinHedin Environmental

Two Passive Treatment Systems that are Community Assets

(Form Follows Function)

Bob HedinHedin Environmental

Mine Drainage

Treatment System

Clean Water

Mine Drainage

Treatment System

Clean Water

2o ValuesValue Adding Form?

Primary Functions

– Reliable production of effluent that meets chemical targets

– Reliable production of effluent that can support biological life

– Contribution to restoration and/or maintenance of functional stream ecosystem

Secondary Functions

• Products that offset treatment costs– Marketable solids– Water– Energy

• Ecological benefits of treatment system• Educational benefits• Aesthetic benefits

Form Follows Functions Observations

• Effective Form Can Follow Good Function• Effective Form Rarely Follows Disfunction• Good Function Rarely Follows Form

Form Follows Function Process

1. Design the system to be functional2. Involve form-adding ideas during design

process3. Set the table for form to be applied after

function is established

Presentation Goal

Present the design process for two functional passive systems in Allegheny County that have become regional assets

• Wingfield Pines (Allegheny Land Trust)• Woodlands Passive System (Pittsburgh Botanic

Garden)

Wingfield PinesPassive System

Wingfield Pines

• Discharge from abandoned underground coal mine to Chartiers Creek

• Pittsburgh Coal seam• Located on land purchased and conserved by

Allegheny Land Trust

Anoxic Limestone Drain

Ponds Vertical Flow Pond

Oxic Limestone Bed

Wetland Ponds Ponds

Oxic Limestone Bed (drainable)

NetAlkaline

Net alkaline Net acid

Net acid

DO, Fe3+, Al all < 1 mg/L(high Fe2+)

Characterize Mine Water

Wetland

Final Discharge

Mn

DO, Fe3+, Al any > 1 mg/L DO, Fe3+, Al any > 1 mg/LFe < 10 mg/L

High Fe2+

Ponds

Repeat As Needed

Mn

Flow pH Alk Acid Fe Al Mn SO4

gpm s.u. mg/L CaCO3 -------- mg/L --------- 1,446 6.6 390 -360 14.6 <0.1 0.3 315

Wingfield Pines AMD

Anoxic Limestone Drain

Ponds Vertical Flow Pond

Oxic Limestone Bed

Wetland Ponds Ponds

Oxic Limestone Bed (drainable)

NetAlkaline

Net alkaline Net acid

Net acid

DO, Fe3+, Al all < 1 mg/L(high Fe2+)

Characterize Mine Water

Wetland

Final Discharge

Mn

DO, Fe3+, Al any > 1 mg/L DO, Fe3+, Al any > 1 mg/LFe < 10 mg/L

High Fe2+

Ponds

Repeat As Needed

Mn

Net Alkaline Water

• No need for alkalinity generation• Contaminants are Fe (and Mn)• Goals:

1. Promote aeration and metal oxidation2. Promote settling of solids3. Promote filtration of solids

Sizing of Wingfield Pines System

• Design for 1,500 gpm flow• Sizing calculations– 7 acres of ponds and wetlands– Available area: 10 acres

• Enough room for creative design• Final Design:– 3.7 acres of ponds– 3.6 acres of wetland

Pond 1 Design Considerations

• Avoid short-circuiting flow• Aerate water to promote iron oxidation• Minimize O&M

Ponds 2-5 Design Considerations

• Avoid short-circuiting• Minimize O&M• Allow observer to easily observe remediation

Wetland Design Considerations

• Avoid short-circuiting flows• Promote vegetation

Miscellaneous Design Considerations

• Minimize earthwork• Shallow groundwater: limit excavation of all

ponds to 825 ft• Account for sewer line through middle of site• Minimize impacts to existing wetlands

Wingfield Pines SystemOctober 19, 2009

Photo provided by PADEP Bureau of Abandoned Mine Reclamation

Pond 1

Pond 2Pond 3

Pond 4Pond 5

Constructed wetland

effluent

Chartiers Creek

System PerformanceSept 2009 – Oct 2011

Flow pH Fe Mn SO4 TSS

gpm s.u. mg/L mg/L mg/L mg/L

Influent 1,446 6.6 14.6 0.3 315 24

P5 out na 7.8 2.6 0.2 301 12

Effluent na 7.9 0.5 <0.1 315 4

Pittsburgh Botanic GardenWoodlands Passive Treatment System

Pittsburgh Botanic GardenWoodlands Passive Treatment System

• Piped discharge from abandoned deep mine• Pittsburgh Coal seam• Primary water source to the Lotus Pond in the

Woodlands Exhibit

Flow pH Alk Acid Fe Al Mn SO4

gpm s.u. mg/L CaCO3 -------- mg/L --------- 8 3.3 0 177 1.3 26.0 1.0 699

PBG Woodlands Raw AMD

pH Alk Acid Fe Al Mn SO4

s.u. mg/L CaCO3 -------- mg/L --------- Woodlands 3.3 0 177 1.3 26.0 1.0 699Wingfield 6.6 390 -360 14.6 <0.1 0.3 315

Two discharges from the Pittsburgh Coal Seam, 5 miles apart

Anoxic Limestone Drain

Ponds Vertical Flow Pond

Oxic Limestone Bed

Wetland Ponds Ponds

Oxic Limestone Bed (drainable)

NetAlkaline

Net alkaline Net acid

Net acid

DO, Fe3+, Al all < 1 mg/L(high Fe2+)

Characterize Mine Water

Wetland

Final Discharge

Mn

DO, Fe3+, Al any > 1 mg/L DO, Fe3+, Al any > 1 mg/LFe < 10 mg/L

High Fe2+

Ponds

Repeat As Needed

Mn

Net Acid Water

• Generate alkalinity and raise pH• Remove metals

Net Acid Water

• Generate alkalinity and raise pH• Remove metals

• Drainable Limestone Bed

Drainable Limestone Bed

AMD

Polishing Pond

Flush Pond

Receiving Stream

Drainable Limestone Bed

AMD

Polishing Pond

Flush Pond

Receiving Stream

Moore DLB System, Somerset County

Sizing of System

Drainable Limestone Bed• Acid loading: 21 ppd acidity (9 kg/day)• DLB sizing calcuation: 225 tons limestone• PBG DLB: 450 tonsPolishing Pond• At least 24-48 hours• PBG Polishing Pond: > 200 hoursFlush Pond• At least twice the flush volume• PPG Flush Pond: 1.5 X flush volume

Secondary Design Concerns

• In Woodlands Exhibit: minimal tree impacts• Polishing Pond location and AMD discharge

location set prior to project– Topographic constraints– Available land constraints

• Planned to be major aquatic component of the Woodlands Exhibit

Drainable Limestone Bed

• 100 ft X 20 ft X 5 ft poured concrete tank• 4.5 ft of AASHTO 3 Vanport limestone• Distributed influent on top of stone• Effluent collection pipe at bottom of tank• Water level controlled by Agri Drain water

level control structure• Draining (once/week) activated by SDS

Concrete tank (filled with 450 tons of limestone)

Perforated influent pipe (4 inch dia)

Perforated drainage pipe (8 inch dia)

Agridrain box

Original terracotta pipe

To solids basin (during DLB drainage)

Riser (for influent sample collection)

Riser (for cleanout)

Riser (for influent pipe cleanout)

To channel and Asian pond (treated water)

Drainable Limestone Bed (Plan View)

Solar panel, battery and computer -to open and close valve in Agridrain box

Concrete tank

Polishing Pond

Flush Basin

Pittsburgh Botanic Garden DLBsolids basin during end of draining

71% of the Al retained in the DLB during routine operations released during draining

Flow pH Alk Acid Fe Al Mn SO4

gpm s.u. mg/L CaCO3 -------- mg/L ---------

Influent na 3.3 0 130 0.5 13.0 0.8 431Effluent 8.3 6.8 216 -188 0.1 0.7 0.2 456

Woodlands Passive Treatment System2013-2015

Questions/Comments