Miller and Smith tour El Paso’s water infrastructure

Dr. Miller and Ph.D. student Ben Smith recently visited collaborator Dr. Zhuping Sheng at the AgriLife Research Center in El Paso, to discuss progress on our joint Managed Aquifer Recharge project. While there, we met his post-doctoral research associate Dr. Shalamu Abudu, his graduate students from Texas A&M and New Mexico Tech, and visiting scholar Dr. Lifei Chen.

While in El Paso, Zhuping was eager to show us its impressive and unique water infrastructure. We started with a tour of the Fred Hervey Wastewater Reclamation Plant, which treats wastewater, up to 12 million gallons per day (MGD) to drinking water standards. The water is then returned to the Hueco Bolson aquifer via injection wells, and the next stop on our tour, infiltration basins, which Zhuping’s group is studying. We then returned to the center, presented the results of our current research, and worked intensely on troubleshooting our model.

We start our tour with a creosote bush in the Fred Hervey Water Reclamation Plant's front garden. It is very representative of the natural vegetation in El Paso. The alternative was to start with the plant's intake screens. This is much more scenic.
View of the plant from the sedimentation tanks. The anaerobic digesters are the tanks on the left.
View of the recently cleaned sedimentation basin.
Screw pumps move water to the secondary treatment phase.
Powered activated carbon and oxygen are introduced to remove organics and nitrogen compounds.
Zhuping and our tour guide, Ron Carrell, standing on the clarifier where bacteria and activated carbon are removed after use.
In the lime mixing room. Lime is added to make the water basic, pH~11, killing viruses and precipitating out unwanted metals and minerals.
This recharge basin hasn't been regenerated in a while. You can see the dark, clay and silt cover, tinted green from biological activity.
A weather station and two evaporation pans capture the rate at which water is lost to the atmosphere, which depends on environmental conditions. A comparison between the upper and lower pan suggests that evaporation is lower at the bottom of the basin, improving recharge rates.
Cutaway of the RO filter. Water enters through the large perforated endcap, shown top left, moves through the layers of the membrane, and exits through the center perforated pipe.
The upper portions of the sandy soil in the basin catches fines, creating a less permeable, clay and silt layer on top. The basin then needs to be regenerated to improve performance. The plastic sampling cap is about three inches in diameter.
The recharge basin is regenerated by scraping the upper crust away with a small loader.
While we were there, the maintenance crew turned the spigot from the reclamation plant back on at full blast.
Even full blast takes time to cover the area.
The Franklin Mountains, formed by tectonic movements during the Cenozoic. These fault block mountains consistent of layered sedimentary rocks, with some granite intrusions. The Rio Grande previously flowed on this side of the range, but has since changed course. We are standing on top of the Hueco Bolson, a basin filled with sediments from a number of origins. Deposit types include lacustrine (lake), alluvial (river), colluvial (gravity), and aeolin (wind blown). The groundwater in this basin is a major source of water for El Paso.
A rock outcrop in the Franklin Mountains, on the west side of El Paso. The interface appears to be between two Ordovician layers: the light bluish-gray El Paso limestone and the dark gray-pink Montoya Dolomite, which has a thin layer of reddish sandstone at its base. Click for the image for a link to the geologic map.
A rock outcrop in the Franklin Mountains, on the west side of El Paso, along "Scenic Drive." The rocks here are from the El Paso formation; in this area, it includes some particularly "cherty" limestones, shown here.
Various water filters used at the plant. Water first passes through the metal sand strainer, followed by the white, fluffy cartridge filter, in order to remove particles down to 5 microns. It then goes through the stars of the show, the reverse osmosis (RO) membrane filters. A cutaway of the RO filter is seen on the far right of the table, while the intact unit is in the middle, and a sample of the unrolled membrane is in front.
Cutaway of the RO filter. Water enters through the large perforated endcap, shown top left, moves through the layers of the membrane, and exits through the center perforated pipe.
Infulent to the plant is extracted from the brackish aquifer under Fort Bliss and the El Paso Airport (left beaker). After treatment in the reverse osmosis filters, it becomes permeate suitable for drinking (middle beaker), and concentrate which must be disposed of (right beaker). The vials show the salt that would remain if all the water in the beakers evaporated.
Each primary treatment unit houses 360 pressure vessels containing RO membranes identical to those shown earlier.
The plant currently has five units, with the capacity to add another. The pumps shown next to each unit provide the pressure to move water through the RO filters, which is very energy consumptive and the main drawback to this method.
Plant director Art Ruiz provides samples of the permeate, which is so pure, all you can taste is paper cup. This water gets blended with untreated, brackish groundwater to make it more suitable for drinking. Chlorine is added to maintain safety during distribution, as is a corrosion inhibitor. The water is then distributed to the public. The concentrate tastes like ocean water.
The pump station sends the concentrate water from the plant to disposal facilities around 20 miles away. The concentrate is then injected deep into the subsurface, where it will not effect the aquifer.
In the near future, the facility will send all of its concentrate to this nearby chemical plant, where a variety of salts and minerals will be reclaimed from it and distributed commercially. Products produced by EWM will include high-purity salt and potash (potassium) fertilizer.
After visiting the plant, we toured the accompanying interpretative center, which had some fantastic water and groundwater based exhibits.
Typically, we would emphasize the "toliet to tap" nature of wastewater reuse, but this exhibit about the water reclamation plant was just too "colorful" to miss.
This bead maze illustrates the water distribution system. Brilliant!
Here, kids get to build water and all of its accompanying impurities!
Why dolomite? Why not dolomite!!!
Despite its water resources issues, ag is still a big business in El Paso. After our plant tour, Zhuping took us to see the pecan orchards.
Cotton is the other major crop in the El Paso area.
The Ysleta Mission is the oldest parish in Texas still in operation. It is located in Ysleta del Sur Pueblo, the sovereign nation of the Tigua tribe.
Ben and Zhuping check out the drainage ditch at the border fence. Fortunately, they don't worry about you approaching from this side.

Spikey looking bush in landscaping box containing sandy soil.

Concrete and metal structures holding dark, murky water.

Empty concrete and metal bowl-like structure with catwalk on top.

Large concrete tank surrounded by metal catwalk and containing black tinted water.

Plant operator speaks with two other men.

Another large soil pit, with some vegetation and fencing surrounding it.

Large soil pit with metal and plastic electronic equipment.

Man with a mallet hammers metal collar into cracked looking soil.

Large soil pit with group of people standing in it.

Water flowing down concrete chanel into large soil pit.

Large soil pit partially covered with water.

Rocky mountains bordered by sandy soil on bottom and blue sky on top.

Cylindrical filters made of metal, fiberglass, and steel.

Pipe-like cylinder wrapped in white and tan plastic and mesh,.

Beakers with identical looking water samples next to vials containing differing amounts of salt.

Texan standing in front of a large array of pipes and tubes.

Warehouse-type steel building holdins arrays of pipes and machinary. Big US flag hangs from ceiling.

While standing in front of a row of spigots, Art hands been a paper cup full of water.

Row of pumps, large metal machinary, under a partly cloudy sky.

Big red metal building with mountains in background.

Museum sign that reads, "Comparing the Bolsons" with an illustration of the Hueco and Mesilla Bolsons which provide water to the El Paso Area.

Museum exhibit on Hueco Bolson Aquifer Recharge Project with a row of non-functional, brightly painted toilet seats beneath it.

Tinker toys marked with various element names, to assemble in to molecules.

Picture of dolomite rock core with the caption, "Why dolomite? After reviewing geologic reports and drilling four test holes, the dolomite formation was determined to be the safest, most economical, and environmental benign alternative to dispose of the concentrate. Overlying shale and limestone formations will prevent upward movement of the concentrate after injection, thus protecting the Hueco Bolson."

Hand holding fresh pecans still in their shells.

The next morning, we toured the Kay Bailey Hutchison Desalination Plant, which is rather unique in its inland nature. The facility extracts brackish groundwater from portion of the aquifer normally not suitable for drinking and treats it using advanced reverse osmosis membrane technology. It can send up to 27.5 MGD of very high quality treated water to the distribution system. Currently, the remaining concentrate, which is highly saline, is then re-injected deep into the subsurface for disposal. However, this waste will soon be diverted to a chemical production plant nearby, which will convert it into industrial products, like fertilizers, for sale in the commercial market. Brackish groundwater desalination appears to be the wave of the future for many arid areas too far from a coastline to use seawater. Our final stops on the trip were in the nearby border town of Socorro, TX, where we viewed the agricultural production, checked out the border “wall” and drainage canal, and saw the oldest mission in Texas.