David Kaminski QED Environmental Systems Inc.

Dexter, MI & San Leandro, CA

Innovations in LFG Wellhead Flow Control and

Gas Well Dewatering

The challenge of managing LFG systems • Gas collection and control systems are typically viewed

as mechanical systems – gas wells and wellhead controls, collection system piping and extraction blowers – with expectation of how these systems will behave based on engineering practices and experience

• In fact, they are combined mechanical and biological systems, and the biological component greatly affects how the mechanical system behaves and performs

• Gas generation & collection rates are affected by barometric pressure, seasonal temps, waste stream, precipitation, etc.

• Biodegradation of waste surrounding the gas wells can impede gas flow, liquid removal and cause silting and clogging of wells

• We design to collect gas, but we have to manage liquids in system to get the gas and maintain regulatory compliance

LFG System Goals: What are operators trying to achieve?

• Control odors and maintain compliance with LFG emission regulations (#1 survey response)

• Avoid NSPS exceedance for Pressure (negative), Temperature (131 F) and Oxygen (5%) (#2 response)

• Maximize LFG energy content (flow rate and methane concentration) where gas is utilized (#3 response)

• Maintain steady vacuum across all wells (#4 response)

• Manage accumulation of leachate/condensate in gas wells & piping (#5 response)

• Control air leaks at the wellhead, flexible couplings and hoses (#6 response)

A new trend in LFG well field management

• For nearly three decades, LFG collection systems were designed using devices for controlling and measuring the gas flow at each well that weren’t ideal for LFG

• Four years ago, QED saw that our customers needed greater control over their LFG well fields. We designed the first “purpose built” LFG wellhead - the Quick-Change Orifice Plate wellhead with our Precision Fine-Tune Control Valve, introduced in January 2012.

• This technology shift is driving a change in LFG well field “best management practices” • Adjusting the well for FLOW rather than applied vacuum

• Using data to guide well tuning rather than a “rule-of-thumb”

• Viewing the well field “holistically” rather than well-by-well

• PVC gate valves were designed for controlling liquids, not for regulating gas flow – small adjustments in valve opening can result in large changes flow and applied vacuum

• Pitot tubes and venturis have flow measurement accuracy errors as high as œ 20%. Union orifice plates can be difficult to change and are easily broken when stuck.

• Flexible rubber couplings can’t support weight, causing air leaks. There’s no access for liquid level measurement, so vacuum is shut off and wells are opened or liquid levels aren’t measured at all.

Traditional LFG wellhead designs

Flow Control Using Gate Valves

Disadvantages

• Non-rising stem, so operator can’t observe valve opening position

• Plastic threads can strip, plastic handle can break off with age

• Seals can fail, dirt and grit can get into threads and gate track, and extreme cold and heat can make valve difficult or impossible to adjust or cause the valve stem to shear when excessive force is applied

• Valve is fully open in just 3 - 4 turns, flow adjustment isn’t linear and is difficult to regulate, especially at low flow rates

Closed Open

Advantages

• Lower initial cost than other valve designs

• Widely available

Traditional Gate Valve

• Designed to provide variable flow control in compressible fluids (gases)

• Larger sizes (2” and above) not effective at low flow rates (10-15 CFM)

• Plastic parts are still susceptible to weathering and failure

• As with PVC gate valves, operator has no indication of valve position

• Commercially available 2-inch PVC angle globe valves cost $230 - $290

Angle Globe Valve for Gas Flow Control

• Patented flow-tuned valve design provides precise, linear control of flow from fully closed to maximum flow

• Rising stem design and highly visible metered scale allows observation of valve position setting, making it easy to quickly return to the exact setting if the valve must be closed

• Rugged stainless steel valve stem and handle make it more durable in harsh outdoor environments

Precision Fine Tune Control Valve™

Precision Fine Tune Control Valve™

Case Study South Texas Landfill – Well 54

The QED Precision Fine-Tune Valve eliminated wide swings in methane concentration and air leaks into the well, improving the overall gas quality while avoiding NSPS exceedance

As little as a 1% increase in methane concentration at a gas value of $2.00/mmBtu in a 50 CFM well can pay for upgraded wellhead and well cap in as little as 12 months

The Value of Better Flow Control – Improved Gas Heat Content

Try the latest QED LFG Calculator at www.qedenv.com/landfillgas2

Additional Annual Gas Value @ 1% Methane Increase Gas Value ($/mmBtu)

1 CFM

5 CFM

10 CFM

25 CFM

50 CFM

100 CFM

$1.50 $8 $40 $80 $200 $400 $800 $2.00 $11 $55 $110 $275 $550 $1,100 $2.50 $13 $65 $130 $325 $650 $1,300 $3.00 $16 $80 $160 $400 $800 $1,600 $3.50 $18 $90 $180 $450 $900 $1,800 $4.00 $21 $105 $210 $525 $1,050 $2,100

Common LFG Flow Measurement Methods Pitot Tubes are intended to fit a wide range of flow rates, but can easily clog with condensate and corrosion, and have poor accuracy at gas flows under 20 CFM (œ 5-10% at best, œ 20% or greater at worst)

Venturis are also a “one size fits all” device, but create significant pressure drop at high flows (>12” WC @100 SCFM) and insufficient pressure drop for reliable measurement at flows under 20 SCFM

Orifice Plate sizes can be selected to match changes in flow rates, but changing plates in unions can be time consuming, requires shutting off gas flow and breaking pipe connections, and gas techs can’t see the plate size without opening the pipe union

The static port measures static (low) pressure

The impact tube measures flow (high) pressure

Pitot Tube Wellhead

For accuracy of plus or minus 2%, the duct diameter should be 30 times pitot tube diameter or greater (for 3/16” tube, pipe size should be 5.625” or greater)

Pitot Tube Design Requirements (From Dwyer Technical Specifications for Pitot Tube Systems)

3/16”

Typical LFG Pitot tube assembly

• If the impact or static tube becomes clogged, measurement accuracy can be affected. The instrument will give you a reading, but you won’t have any indication that it’s not accurate.

• If the gas velocity is low, the differential pressure is very small and hard to measure accurately. Error in the instrument could be greater than the measurement! Pitot tubes don't work very well for very low velocities.

• Typical LFG flow velocities in 1” – 3” pipe diameters often fall well below the minimum velocity to maintain œ3% accuracy

• Meters used to measure LFG flows with Pitot tubes don’t meet the needed accuracy to attain accurate measurements:

– GEM 5000: 1.6” WC (œ4mbar) typical, 6.0” WC (œ15 mbar) max

– Elkins Envision: œ0.1375” WC low range

Pitot Tube Operating Conditions

Pitot tube wellheads don’t generate sufficient pressure drop in many wells to get an accurate measurement with common LFG instruments. In a 2” wellhead, 0.5” WC pressure drop isn’t achieved until 40 CFM

Typical Wellhead Gas Flow Velocities

• While LFG wells can achieve flow rates e 100 CFM, they are typically lower, and can easily be below 10 CFM

• Flow velocities in wellhead pipe sizes of 1” to 3” are often too low to get accurate measurements with Pitot tubes

• Orifice plate wellheads have the advantage of changing orifice sizes to match the gas flow to achieve desired pressure drop for accurate measurement

Velocity Too Low

Orifice plate wellheads have the advantage of matching the plate size to achieve the desired pressure drop at any flow rate

Performance of Orifice Plates vs Pitot Tubes

Values derived using Industrial Flow Calculator for LFG at 100° F, 50/50 mixture of CH4 and CO2 at 20” WC vacuum and 100% humidity. Pitot tube values from manufacturers data.

• Uses proven orifice plate technology for accurate and repeatable flow measurement

• Plates can be swapped out under vacuum in seconds to achieve desired differential pressure

• No time wasted shutting down the control valve, breaking pipe connections or rebalancing the well

• Removable dust cover allows for easy confirmation of plate size, reducing reporting errors

Quick-Change™ Orifice Plate System

Simply loosen the Quick-Change collar and slide the plate out to remove condensate build-up. Plate can be quickly wiped clean if desired.

Slip the clean plate back into the wellhead and tighten the collar to take an accurate flow measurement

The Quick-Change Orifice Plate Wellhead is the only flow measurement device that can be cleaned without shutting down the well, breaking a pipe union or removing the wellhead

• Color coded for easy size identification

• Orifice diameter is clearly marked in raised type on each plate

• Strong, glass-filled high-temperature nylon plastic won’t break or corrode, and don’t get hot like metal plates

• Lightweight – a kit of six plates can be easily carried in you pocket

NEW Color-Coded Plastic Orifice Plates The new molded orifice plate kits from QED have several advantages over metal or other plastic orifice plates

• Won’t leak between uses due to weathering or heat

• Bird proof! Birds can’t pull off caps and cause air/gas leaks

• Strong, glass-filled engineering plastic won’t break or corrode

• Unique barb design - easy connection/removal, positive seal

NEW QED Easy Port™ Wellhead Fittings

The new Easy Port molded, positive-seal fittings are easy to open, easy to attach and remove gas meter tubing

LFG Flex Hose • LFG flex hose, made from clear flexible vinyl

(PVC), is subject to weathering from UV exposure and the heat from LFG

• Over time, the hose will discolor or “brown”, losing flexibility and eventually cracking, causing air leaks into the gas system

NEW Solarguard™ UV-resistant

Flex Hose

Typical Solarguard™ Installations

What’s Next from QED? • 2nd Generation Wellhead Molded Design

• All major components molded from high-strength, high-temp engineering plastics

• Two-piece valve design improves serviceability

• Operating temperatures to 180° F

• Self-regulating LFG control valve • Keeps vacuum or flow at desired set point

• Uses a solar-powered actuator that “wakes up” several times each day, makes adjustment if necessary

• Intended to reduce swings in flow from changes in barometric pressure and system vacuum to maintain compliance and maximize gas extraction for energy use

What’s next in LFG management? NSPS/EG • Proposed August 27, 2015 revisions to the New Source

Performance Standards (NSPS) and Environmental Guidelines (EG) will change some aspects of wellfield management and reporting, and may pull more sites under those rules

• The good news: elimination of monthly PTO reporting, HOVs for T and O2, and the “5/15” compliance cycle; site will still measure but not report T & O, and longer compliance time for P issues

• The bad news(?): EPA target is to further reduce emissions • NMOC emission trigger for GCCS drops from 50 Mg to 34 Mg

• Surface emission monitoring will add measurement at every penetration in the landfill to current site walk/grid approach

• Better wellbore seals, gas well dewatering and better wellhead flow control are being encouraged as “Best System of Emission Reductions” (BSER)

Typical Landfill Gas Well Components

Rock or Gravel Backfill Perforated

Pipe/Screen

Gas Collection Header Pipe

Annular Seal

LFG Wellhead Flow Control Valve

Why Manage Landfill Liquids? Leachate Collection & Recirculation

• Regulatory compliance (maximum head limit against liner)

• Minimize side slope seeps, ponding and odors

• Gradient control in unlined landfills to prevent leakage

• Leachate recirculation to accelerate gas production and treat leachate (reduce BOD/COD)

• Maximize gas flow from wells to increase profits, reduce fugitive emissions and odors

• Reduce liquid accumulation in piping (low spots, sumps)

• Maintain steady operation of power generation systems

• Prevent damage to blowers, generators and flares

Condensate & Leachate in Gas Wells/Piping

Leachate Flow in Typical MSW Landfill

Monitoring Probes

Gas Extraction Wells

Waste Cells

Gas Header Pipe

Flare/ LFGTE Plant

Leachate Plant

Leachate Flow

Daily Cover Material

Daily Cover Practices • Common practice of using soil as daily cover creates

hydraulic barrier to leachate movement

• Results in lateral movement of leachate and pockets of “perched” leachate, high liquid levels in gas wells

• Using alternative daily cover materials can improve leachate collection efficiency, minimize seeps and ponding, reduce liquid accumulation in gas wells and improve gas movement through the waste material

• Spray-on foam, recycled cardboard or tarps as daily cover allow for better vertical leachate movement and distribution in waste

• Yard waste can be used as daily cover, breaks down over time and generates additional gas

• Compost has also been used, very effective at controlling odors

PROBLEM: • Leachate/condensate

accumulate in gas wells, blocking screen openings and reducing gas flow

• Long-term accumulation can clog the well screen and backfill, leading to permanent reduction in gas flow from the well

• Leachate recirculation can accelerate leachate buildup in gas wells

Liquid in LFG wells and surrounding waste cause gas and liquid to compete for pore spaces in waste and results in high shut-in gas pressure, causing leachate seeps or blow-outs and silt in wells while reducing gas collection rates

Gas Flow vs. Liquid Levels in Wells

White Areas = High gas flow

Blue Areas = Low/no gas flow

Blue Areas = High Liquid Levels

(Clarke, 2007)

LF

G F

low

, SC

FM

SOLUTION: • Install a dedicated

pumping system to dewater the well to increase gas flow and maintain long-term viability of the well

• Increases the zone of influence around well, reducing LFG emissions, odors and air leaks into system from “over pulling,” improving gas quality and maintaining regulatory compliance

Dillah, McCarron and Panesar, 2004

Zone of Influence Leachate accumulation effectively shortens the length of the well intake and reduces the “zone of influence” in the waste

Dewatering the well and surrounding waste can increase the zone of influence with no increase in vacuum, reducing the risk of air infiltration and maintaining gas quality

LFG Collection Rate Improvement Gramacho Landfill, Brazil

* Average of 6-8 flow measurements taken over 30 days (August 2009) † Single flow measurement taken after dewatering (October 2009)

LFG Flow (SCFM) Change in LFG Flow

Well Before

Pumping* After

Pumping† SCFM % 10 39 58 20 51% 16 25 40 15 59% 39 243 335 91 38% 43 25 49 24 95% 44 43 58 15 35% 45 17 27 10 61% 47 26 73 46 176% 54 40 79 39 99% 55 37 82 45 120% 64 59 98 39 66%

TOTAL 554 898 344 62%

As little as 5 CFM additional gas flow per well at $2.50/mmBtu can pay for a $3,300 dewatering pump system in just one year, with additional annual revenue generated thereafter

Gas Well Dewatering - Economics

Gas Value ($/mmBtu)

1 CFM

5 CFM

10 CFM

25 CFM

50 CFM

$1.50 $394 $1,970 $3,940 $9,850 $19,700 $2.00 $525 $2,625 $5,250 $13,125 $26,250 $2.50 $657 $3,285 $6,570 $16,425 $32,850 $3.00 $788 $3,940 $7,880 $19,700 $39,400 $3.50 $920 $4,600 $9,200 $23,000 $46,000 $4.00 $1,050 $5,250 $10, 500 $26,250 $52,500

Additional Annual Gas Value @ 50% Methane

Benefits of LFG Well Dewatering • Maximize gas collection rates and zone of influence

• Increase revenues where gas is utilized

• Reduce fugitive emissions, odors

• Maintain regulatory compliance in gas wells

• Reduce liquid accumulation in collection piping & sumps

• Maintain steady operation of generators and flares

• Prevent damage to blowers, engines and flares

• Increased useful life of LFG wells by reducing clogging and encrustation of well screens and backfill

Landfill Pumping is a Challenge • More challenging than nearly any

other industrial pumping application

• Elevated temperatures to +180° F accelerates wear, attacks materials

• High levels of suspended solids can clog pumps and well screens

• High dissolved solids clogs pumps, discharge piping and headers

• Foaming potential can reduce flow rate or cause pumps to stall

• Viscosity greater than water increases energy needed

• Corrosives and aggressive organics

• Extreme pH at some sites (< 1.5 pH)

Pumps and leachate don’t like each other…

Gas Well Dewatering Challenges • No matter what type of pump is

used, some degree of maintenance is required

• The cost of maintenance over time can be the largest percentage of total life cycle cost

• QED recognizes that pumps in some wells require frequent maintenance, and some will stall/stop even when maintained

• QED has introduced design enhancements to reduce maintenance, speed cleaning and reduce downtime and stalling

Easier disassembly: removing four bolts on bottom inlet allows complete pump disassembly in minutes – no turning of the inlet assembly or O-ring hang-up/dragging

Easier service: quick-release clip on actuator rod allows quick float removal for easier cleaning. Pump body has a high-polish ID finish to reduce solids build-up and precision bore sizing to improve O-ring fit

Increased durability: All metal parts are 304SS or higher for improved corrosion resistance; plastic parts are high-strength & high-temperature engineering plastics (PVDF, PEEK)

Increased warranty: 5-year full warranty with no pro-rating in later years

AutoPump® *AP4+ designed for easier cleaning

* Patent Pending

AutoPump AP4+ Design Enhancements

Standard Float vs. Wide-Slot Float

• Wide-Slot Float – actuator rod slot is wider and cut through to center to prevent solids lock-up between float and actuator rod

• Low-Friction Float Coating – reduces build-up of solids on float to extend cleaning intervals, speeds cleaning and reduces chance of damaging float during cleaning

• High-polish 316L SS Center Rod – reduces friction, solids adhesion and corrosion

• Low-Friction Float Guide Plate –made from engineering plastic to have lower friction than steel and prevent scratching of center rod

AutoPump® AP4+ Design Improvement

New Air Valve Mechanism Design

• The new “captured pin” design eliminates need for fasteners, clips or cotter pins at valve stem

• Improved reliability, easier to service – exhaust seat is easier to adjust

• Now on all AP4+ models!

Net result – the first low-maintenance air-powered pump:

• The Ultra lasts up to 10 times longer between cleanings and takes up to 50% less time to clean

• The Ultra combines all of the design features and rugged reliability of the AutoPump AP4+ in an innovative design that reduces build-up of solids and sticky deposits on the float and center rod

– Greater reliability in challenging applications

– Fewer pump pulls for maintenance

– Cleaning is faster and easier

Design Features

Non-stick float and electro-polished center rod reduce solids buildup, low-friction engineered plastic guide plates reduce pump stalling

Non-stick, high polish finishes make cleaning easier – can be as easy as “wipe and rinse”

All metallic parts are 316-grade SS for greater corrosion resistance and reliability

Field tests compared the new AutoPump Ultra to existing pumps and reported the following results:

“Teardown and cleaning took absolutely no effort”

“No soaking required”

“Only needed a water spray to clean”

“Removed residue with some clean water and the swipe of a hand”

“Easier to clean by 50%”

“It’s been running for four months and I haven’t had to clean it yet!”

Maximum uptime… …Minimum Downtime

Ultra pump beta test after 1 year – 10/20/15

Cleaning Frequency

Pump Pulls/Year

AP Ultra Frequency

Pump Pulls/Year

Annual Pulls Saved

Savings @ $100/pull

Savings @ $150/pull

Savings @ $200/pull

4 weeks 13 18 weeks 3 10 $ 1,000 $ 1,500 $ 2,000

2 weeks 26 8 weeks 7 19 $ 1,900 $ 2,850 $ 3,800

2 weeks 26 22 weeks 3 23 $ 2,300 $ 3,450 $4,600

1 week 52 19 weeks 3 49 $ 4,900 $ 7,350 $ 9,800

Annual Pump Cleaning Savings with AutoPump® Ultra

Using the AutoPump AP4 Ultra and reducing your cleaning frequency from monthly to quarterly at $100 per cleaning event saves $800 annually and frees up as much as 16 hours of technician field time

Standard Pump AutoPump Ultra

• Designed to guide pump tubing out of the well without kinking and to reduce lifting effort

• Deep vee roller bolts onto flange or straps to outside of 6” & 8” well casings

• Currently being field tested at two sites with positive feedback

Pull puller tool to speed maintenance

What’s next in air-powered pumps? • Buildup of precipitate solids on pumps, piping and wells is the single

toughest problem to solve. Approaches have included chemical amendments and alternative designs for well, piping and pumps.

• One possible solution to increase operating time between maintenance pump pulls is to increase operating clearances on key air-powered pump components.

AODD Pumps – An Alternate Approach for Challenging LF Pump Applications • Air-operated dual diaphragm

(AODD) can be an alternative to submersible pumps for applications where chemistry, solids loading or physical limitations exist, such as:

• LFG wells

• Condensate sumps

• Horizontal Gas Collectors

• Side slope leachate risers

• QED combines class-leading AODD technology with all-pneumatic control systems designed for landfills

Cage frame mount for easy transport and temporary use

Dewatering a horizontal gas collector

Mounted inside a condensate sump

AODD Pump Applications

Questions?

David Kaminski QED Environmental Systems, Inc.

DKaminski@qedenv.com Phone: 800-624-2026 WWW.QEDENV.COM

Kansas contact:

Bill Reetz A Better Earth, LLC Tel: 785-764-1674

Bill@ABetterEarthLLC.com