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Leachate System Clogging -The Springfield Experience
Nathan HammJuly 17, 2017
1
MWCC 2017
Presentation Overview
2
• Facility Background
• Challenges
• Technical Approach
• Findings
• Remedial Approach
• Design Recommendations
MWCC 2017
Facility Background
3
• MSW Landfill• 120 Acres Pre-Subtitle D
• 22.2 Acres Subtitle D
• Historically Trucked Leachate to WWTP• Up to 15 MGY
• Leachate Pumping System and Forcemain• Constructed in 2010
• Duplex Pump Station from Existing Storage Lagoon
• 9 Mile, 4-Inch SDR 9 and SDR 17 HDPE Forcemain
• Design Pump Flow 100 - 110 GPM (2.6 ft/sec)
• >74M Gallons Pumped Since Commencement
MWCC 2017
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Pump Station
MWCC 2017
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Pumping System
MWCC 2017
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Forcemain Construction
MWCC 2017
Challenges
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• July 2016 Leachate System Stops Operating• Pumps Ramp Up and Shut Down (High Pressure
Limits)
• City Attempts to Restore Service• Perform Pump Maintenance
• Lagoon Intake Screen Dislodged
• Turtles and Deer Bones
• Attempts to Video / Camera Forcemain
• Jetting Contractor Cleaned Select Section
• Additional Clogs
MWCC 2017
Technical Approach
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• Determine Extent of Problem• Forcemain Pressure Analysis
• Camera / Video Select Forcemain Sections
• Assess Scale / Sludge Formation Mechanisms• Leachate Sampling and Analysis
• Sludge Sampling and Analysis (Lagoons & Forcemain)
• Develop Remedial Alternatives/Recommendations
• Implement Selected Remedial Solutions
MWCC 2017
Findings - Forcemain Pressure Test
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0
15
30
45
60
75
90
105
120
135
150
165
180
195
210
0
15
30
45
60
75
90
105
120
135
150
165
180
195
210
14:25 14:35 14:45 14:55 15:05 15:15 15:25 15:35
Pre
ssu
re,
PS
I
Time, Minutes
Forcemain Pressure Test Using Pump House Pumps
Pump
'AR-2"
"AR-4'
"AR-5"
"AR-6"
"AR-8"
"AR-10"
MWCC 2017
Findings - Forcemain Camera
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MWCC 2017
Findings - Leachate Analysis
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• High TDS and Dissolved Metals• TDS 3,000 mg/L
• Calcium, Iron, Magnesium, Sodium
• Moderate to High Organics Concentrations
• Scale Index Analysis and Precipitate Modeling• High Scaling Potential (Calcite-CaCO3 and Siderite-FeCO3)
0
200
400
600
800
1000
1200
1400
Oct-01Oct-03Oct-05Oct-07Oct-09Oct-11Oct-13Oct-15
CO
D,
mg
/l
Chemical Oxygen Demand
0
50
100
150
200
250
300
Oct-01Oct-03Oct-05Oct-07Oct-09Oct-11Oct-13Oct-15
Am
mo
nia
as
N,
mg
/l
Ammonia as N
MWCC 2017
Leachate Lagoon Sludge
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MWCC 2017
Pumping System Strainer Basket Sludge
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MWCC 2017
Forcemain Sludge
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MWCC 2017
Forcemain Sludge
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MWCC 2017
Findings - Sludge Sampling and Analysis
– EMSL Analytical
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Sample ID: 1 2Description: Lagoon Sludge Forcemain SludgeGrouping Analyte Contribution Contribution
Liquid Phase: Water 45 – 55% 35 - 45%Solid Phase: Plant Matter 1 - 3% 1 - 2%
DecomposedOrganic Matter
1 - 3% 1 - 2%
Quartz 5 - 10% <1%Calcium Carbonate 30 - 40% 5 - 10%Mica <1%Iron Oxide 2 - 5% 40 - 50%UnidentifiedInorganics
1 – 2% 10 - 20%
BiologicalOrganisms:
Bacteria Trace Trace
MWCC 2017
Findings - Summary
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• Sludge / Sediment Buildup Throughout Forcemain• Loose Sludge with “Chips” vs. Hard Cementation
• Heaviest Buildup in Middle Sections
• Observed Scaling on Pipe Walls in Section Closest to Pumps
• Significant Sludge Buildup in Lagoon (>18-Inches)• Sucked into Pumping System
• Sludge Chemical Composition Different Between Lagoon and Forcemain
• Leachate Conducive to Precipitate Scale Formation
MWCC 2017
Remedial Approach
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• Modify Lagoon Intake Structure
• Phased Cleaning Approach• High Rate Flushing and Suction• High Pressure Jetting• Chemical Cleaning (Acid Treatment)
• Camera the Pipes After Cleaning to Observe Effectiveness
• Develop a Long-Term Routine Maintenance Program• Pigging• Lagoon Aeration• Routine Flushing or Jetting• Chemical Scale Inhibitors• Biocides
MWCC 2017
High Rate FlushingFlushing Line North of AR-5 - Collecting with a Vac Truck
Location Station Valve AdjustmentDist to End,
Feet
Max Pressure,
psiFlow Rate,
gpmGallons for one flush
# of Flushes
Flush Time (min)
Gallons Required
Set Up Break Down, Hrs RT Haul, mi Load Rate
Cycle Time, Hrs
Pump Distance
AR-3 to AR-5 26+00
Open AR-5 NorthClose AR-5 SouthClose AR-3 NorthOpen AR-7 SouthVac Truck at AR-5
Pump Truck at AR-3 8500 150 150 5548 1.5 55 8323 1.5 16 300 1.66 372
AR-3 to AR-1(accounting for
6" pipe) 26+00
Open AR-5 SouthClose AR-3 SouthOpen AR-3 NorthClose AR-1 NorthVac Truck at AR-3 2234 150 150 2384 1.5 24 3575 1.5 16 300 0.83 372
Pump House to AR-1 26+00
Open AR-3 SouthClose AR-1 SouthOpen AR-1 North
Pump at AR-1Vac Truck or Hose at PH 2600 200 150 1697 1.5 17 2546 1.5 5 100 0.99 200
Pump House to Leachate Pond
Open AR-1 SouthPump Truck at PH
Open Suction Line ValvePump to Leachate Pond 200 100 200 522 3 8 1567 1.5 5 100 0.99 20
Monitor Pressure at injection point Subtotal
104 min 16010 gal 6 hr 4 hr 12 hr
Frac Tank Locations Totals10 hr 107911 gal 19 hr 24 hr 53 hr
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MWCC 2017
Forcemain Pigging
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Foam Swabs and Scouring Pigs
MWCC 2017
Forcemain Pigging
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Remote Tracking System
MWCC 2017
Pigging - Launcher
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MWCC 2017
Pigging – Catcher System
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MWCC 2017
Pigging – Before and After Swabs
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MWCC 2017
Pigging – Before & After
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MWCC 2017
Lesson Learned – HDPE Restrictions
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MWCC 2017
Chemical Treatment
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• Acid Blends
• Large Volume Requirements
• Safety Concerns
• Disposal
• Cost
MWCC 2017
Overall Conclusions
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• Analyze Leachate for Scaling Potential During Design
• Design Forcemain Systems for Sediment Resuspension• > 3.5 ft/sec for loose scale removal and resuspension
• < 8 ft/sec to avoid excess head and water hammer
• Forcemain Pipe ≥ 4-inch Diameter to Facilitate Maintenance
• Design for Maintenance• Cleanouts Spaced 400-500 ft Maximum
• Pig Launchers and Catchers
• Chemical Treatment Equipment
• Develop and Follow a Routine Maintenance Plan
MWCC 2017
Questions
Nathan Hamm, P.E.
SCS Engineers, Inc.
7311 W. 130th Street, Suite 100
Overland Park, KS 66213
nhamm@scsengineers.com
(913) 749-0705 Direct Office Line
29
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