HDPE LinedEvaporation Ponds

Presented by:

Neil Nowak, PE

HDPE LinedEvaporation Ponds

TOPIC OF PRESENTATION:

Use of High Density Polyethylene (HDPE)as the top layer of brine (production) andflow back water evaporation pondfacilities.

HDPE Lined Evaporation PondsNot Extinct Yet?

PURPOSE:• Dispose of production

water and flow backwater generated fromoil and gasdevelopment.

• Several million barrelsof production water andflow water is generatedeach year in themountain states.

• Other types ofevaporation anddisposal facilities exist.

SELECTION OF TECHNOLOGY:

Technologies for managing production andflow back water:

– Disposal injection back into the ground

– “Frac” injection of the water back down intothe production formation to enhance yield

– Treatment for surface discharge or reuse

– Evaporation

High DensityPolyethylene (HDPE)designed as theprimary or top layer ofthe lined ponds inorder to protect thegroundwater and toenhance theevaporation of theproduction waterwithin the ponds.

DESIGN…WHY HDPE?:

Textured 60-mil HDPE for top liner of ponds not buried.

• Ultraviolet (UV) degradation resistance.

• Durability (20 plus years, Ivy 2002).

• Chemical resistance.

• Black color enhances evaporation of water.

• HDPE was chosen over clay liner and othergeomembranes due to being the most compatible withsite conditions and regulations (i.e. exposed to sunlight,desiccation, and hydrocarbons).

• Textured surface used to aid with traction if operationspersonnel fall into ponds, and to increase slope frictionand stability.

DESIGN (continued):

CONSTRUCTIONPonds designed and constructed with single or twogeomembranes over compacted clay or GCL and ageonet leak layer in between to monitor the primary linerfor leaks.

CONSTRUCTION

Geomembrane panels are welded together and tested forstrength throughout the installation performed by trainedand certified technicians.

CONSTRUCTION

Geomembrane panels are welded together and tested forstrength throughout the installation performed by trainedand certified technicians.

Projects located insemi-arid regions:

– Eastern Utah(Danish Flats) nearCisco

– North of Baggs, WY(Southern Cross)

– Cheyenne, WY (SiloField)

– Southeast NewMexico (CRI)

INTRODUCTION:

Production water delivered to the sitesvia tanker trucks for disposal byevaporation.

• Danish Flats facility went operational with4 ponds in May 2008, and currently at 14ponds operational as of Oct 2011.

• Southern Cross facility went operationalwith 2 ponds in July 2008 with anadditional 2 ponds constructed in 2011.

• Silo Field near Cheyenne, WY iscurrently being built and will start with 3ponds and state-of-the-art oil/waterseparation equipment.

• Controlled Recovery, Inc. (CRI) nearHobbs, NM. An existing facility to beupgraded, will start lining in December2011 with 5 ponds, and state-of-the-artoil/water separation equipment.

INTRODUCTION (continued):

• Each constructed evaporation pond is approximately 5.2 acres atthe top of the berm (DF, Utah=70 acres of ponds, Southern Cross,WY=20 acres of ponds, Silo Field, WY will be 15 acres of ponds,and CRI, NM will be approximately 20 acres of ponds).

• The evaporation ponds are designed to hold at capacity:– 330,000 barrels (42 gallon/barrel) of water at 12 feet depth– 580,000 barrels at 22 feet deep

• Production water (brine water) or flow back water is delivered bytruck and moved from an off-loading area to the ponds by gravity, orvia force main after removal of the hydrocarbons throughpretreatment.

• Hydrocarbons are removed through various pretreatment processes,including gun barrel tanks, sludge pits and state-of-the-artequipment.

• Emissions from pretreatment are routed to a control device.

PROCESS:Truck receiving area/off-loading via hose and pipeline toinitial phase separation in acceptance pits or gun-barreltanks (Danish and Southern Cross), or through state-of-the-art oil/water separation equipment (Silo Field andCRI).

PROCESS:At Danish Flats, off-gases from acceptance pits and gun barrel tanksare routed to a control device, which includes a thermal oxidizer andscrubber.

PROCESS:

At R360’s facilities at Silo Field and CRI, the water will be receiveddirectly from the trucks and be directed through state-of-the-artoil/water separation equipment that will reduce the hydrocarboncomponent in the water to 30 parts per million (ppm) or less (non-sheen producing). The treatment design is currently beingconstructed.

Off-gases from the equipment will be routed to a control device,which will include a thermal oxidizer and scrubber.

The effluent from the treatment equipment will flow directly to theHDPE lined ponds for evaporation. No sludge ponds.

PROCESS:

From acceptance pits/gun-barrel tanksthe water moves by gravity to theHDPE lined settlement/sludge pond forlast stage of hydrocarbon removal andcollection at Southern Cross andDanish Flats. However, these sludgeponds require bird-netting to cover thewater, which will likely have floatinghydrocarbon.

These sludge ponds also are emissionsources for volatile organic compounds(VOCs) and may be concerns with airpollution permitting if the sheen is notremoved promptly.

PROCESS:• The water is fed by gravity or force main pipe to the

evaporation ponds from the settlement/sludge pond ordirectly from the oil/water separation equipment.

EVAPORATION:• Ponds designed to store and evaporate

production and flow back water.

• Top layer of the pond liner is texturedsurface 60-mil HDPE.

• Climate at these sites are ideal in thesemi-arid mountain west for evaporationduring May through October.

• HDPE liner aided evaporation due to blackcolor of surface.

EVAPORATION (continued):

• Design evaporation rate estimated to be approximately 50 inches of waterannually at Danish Flats, and 40 inches at Southern Cross.

• Actual evaporation encountered during 2008 was nearly 70 inches (due toshallower water in ponds) and in 2009 and 2010 was nearly 60 inches atDanish Flats; and approx. 55 inches at Southern Cross.

• Design evaporation at Silo Field and CRI are both similar atapproximately 45-46 inches per year.

OPERATIONS:

• During ideal conditions for evaporation (May throughOctober) of water which has been found to be up to 1-inch (approx) per day on the hottest days in July inAugust.

• During low evaporative months of November throughApril, the facilities store the water in the ponds.

OPERATIONS:

Ideal conditions forevaporation occurswhen:– The air temperature

is above 80 degreesFahrenheit andsunny,

– The wind blows, and

– The level of water ina pond is not greaterthan 3 feet deep.

MAINTENANCE:

• After several years of operation (possibly 8 to 10years), the “salt” from the production or brinewater builds up as precipitate in the pondbottoms.

• Upon excessive build-up of sediments or uponclosure, then all the water is evaporated and thesediments dried and either removed or thefacility buried (closure).

CONCLUSIONS:

• Evaporation facilities are serving a need of the regionand the oil/gas industry.

• Evaporation of production and flow back water is one ofthe low cost methods for disposal.

• HDPE as the top layer is the right choice due to provendurability and resistance to UV and chemicaldegradation.

• HDPE improves the evaporative ability of the ponds withthe black color of the liner.

HDPE Lined Evaporation Ponds

HDPE Lined Evaporation PondsSouthern Cross with two ponds operational (2010):

HDPE Lined Evaporation PondsSilo Field under construction 2011, includes GCL, and

double geomembrane with leak layer in between:

Questions?Thank You!

Presented by:

Neil Nowak, PEPhone: 720-529-0132

Email: nnowak@weaverboos.com

Website: weaverboos.com