The Northeast Water Purification Plant (NEWPP) is a $1.4 billion dollar expansion to the water system of Houston and the surrounding cities. With a planned capacity of 320 million gallons a day the tankage on the project was varied and demanding. With a typical water treatment plant, the tanks provided would be shop fabricated out of specialized metals or linings that can only be applied in a shop environment. Due to the scale of the storage and process needs the tanks had to be field erected, and with that, the means and methods of providing the tanks had to be customized and modified to provide the protection needed.

All of the tanks had specialized examination requirements, tolerances, design conditions outside of API-650.

For the two Acid Storage Units we provided twelve tanks overall. Four of the tanks were 304 Stainless Steel with Dome Roofs. Four of the tanks were carbon steel with a rubber liner. The rubber liner was provided over the entire interior surface including the roofs. The last four of the tanks were carbon steel tanks with a dome roof. However, due to the process requirements these tanks were insulated and also had a PVC Bag Liner that was field installed. These tanks were built in the peak of the pandemic which presented significant challenges. These PVC Bag Liners are specialized systems with limited suppliers. The original selected installer was Canadian. When the tanks needed to be installed there was limited options for their crews to be able to both get to the US and then back to Canada. So, we had to do remote video training of the installers and use video surveillance to have the Canadian supplier review the details. All of the carbon

steel tanks had exterior coatings. A specialized blasting procedure was used due to the proximity of other trades and work products in the area.

For the Dewatering Building, we provided seven total tanks. All of the Tanks were stainless steel. Passivation and Pickling had to be performed for all seven of these tanks. Due to the tight final install location, three of the tanks had to be rectangular. Significant horizontal and vertical stiffening had to be applied to support the loads and the lifting process. The other four tanks had to have a 100% drain, so they were made with a conical bottom and supported by legs. Due to the process requirements and installed location, the leg and bottom load were handled by installing stiffening rings of over 1″ thick and 12″ wide.

With nineteen total tanks we provided virtually every type of tank. Insulated tanks, stainless tanks, cone bottom tanks, rubber lined tanks, painted tanks, rectangular tanks, shop built tanks, and PVC Bag Lined tanks.

Award Name

API 650 Atmospheric Oil Storage Tank

Company Name

Caldwell Tanks, Inc.

Award Year


Product Details

  • Northeast Water Purification Project Tanks
  • Houston Waterworks
  • Humble, TX

Date Completed

August 1, 2022

Construction Standard

API 650

Overall Height

24' -0" (Tallest)


40' -0" (Largest)



Steel Tonnage Used


Steel Thickness

3/16" - 3/8"