Attachment_3_Elephant_Butte__NM_3_Steel_Tanks_Insp_Rpt_0001.pdf

February 2, 2022

Tina Villegas

Bureau of Reclamation

555 Broadway Blvd. NE, Suite 100

Albuquerque, NM 87102

Re: Elephant Butte Steel Water Storage Tanks Inspection

Ms. Villegas, This tank inspection report was commissioned by the United States Bureau of Reclamation (Bureau) to assess the condition of the interior and exterior of three (3) identical steel water storage tanks on the same site in Elephant

Butte, New Mexico. On November 10 and 11, 2021, D&R Tank’s certified NACE inspector, Noel Vargas, and

Dusty Vega conducted the inspections and found the tanks to have the following features:

Number of Tanks Three (3)

Volume 17,000 Gallons Each; 51,000 Gallons Total

Diameter 10 feet

Height 30 feet

Purpose Potable Water Supply

Tank Type Welded Steel

Roof Self-Supporting Cone

Foundation Type None

Roof Hatch(es) One 16” Round Hatch (no lock)

Shell Manway(s) One (30” Diameter) – Installed by D&R Tank on 11/9/21

Vent None

Ladder(s)/Stairs Exterior: Steel Ladder with Ladder Guard; Interior: Steel Ladder

Level Monitoring System Mechanical Target Board with Float System

Inlet(s) One 6” Inlet Pipe (approx. 6” above floor)

Outlet(s) One 6” Outlet Pipe (approx. 6” above floor)

Drain(s) 2” Shell Nozzle

Overflow 2” Shell Nozzle with 90 Deg. Bend at Top of Tank

Cathodic Protection None

In order to gain entry, D&R Tank installed one (1) 30” diameter shell manway on each tank. Overall, the tanks were found to be fair and functional condition but are in need of rehabilitation in the very near future.

With proper rehabilitation these tanks will last several decades to come.

All observations below are compared to current codes, standards, and best industry practice, although it is understood that this tank may have been constructed under older codes and standards. The following summarizes the observed conditions:

• Interior and exterior coatings are at the end of life and in very poor condition with only 1.5 – 3 mils of remaining coating thickness in some locations. Minimum exterior coating thickness should be 6.5 mils.

• On all three tanks the roof and shell wall plate conditions were found to be satisfactory and relatively free of corrosion.

• Floor plate conditions were found to be poor with several ¼” diameter holes that required patching just to put the tanks back in service after the inspections. An oily, black manganese bacteria sludge was found at the bottom of each tank approximately 6” thick. This material was removed and disposed of by Lago

Rico as a subcontractor to D&R Tank.

• The tanks are installed directly on the ground with no tank foundations. Per AWWA, tanks should have a foundation consisting of a steel ring, concrete slab, or concrete ring wall. In addition, standpipes such as these tanks, typically are equipped with anchor bolts which resist wind and seismic induced tipping.

Instead, the tanks have been equipped with guywires that appear to be in satisfactory condition and are an acceptable method of securing the tanks.

• Exterior ladders were observed to be in good condition and included a locking ladder guard. Interior ladders were found to be corroded and will need to be replaced. Both ladders were not equipped with a fall protection system which is required by OSHA for tanks 24 feet and higher.

• The overflows consist of 2” shell nozzles with 90-degree bends. This overflow is not large enough for the tank as per AWWA, it should be at least as large as the inlet pipe size (i.e., 6”). In addition, per

AWWA, a proper overflow should extend to 12” to 24” from the ground and ensure that all drainage runs away from the foundation.

• The tanks do not have vents, only overflows. Per AWWA, tanks are required to have separate vents and overflows.

• The 16” diameter round roof hatch was found to be loosely secured with two bolts/nuts. There was no gasket or lock. The hatch should be firmly secured with additional bolts/nuts and a gasket. This will ensure a sanitary seal which is required by EPA/NMED. In addition, there were no guardrails on the roof.

• The inlets, outlets, drains were observed to be in relatively good condition with minor corrosion and meet current AWWA and NMED standards.

• All isolation valves appear to be frozen and are not functional. They will need to be replaced.

• The target level system is functional on Tank #2 (middle tank); however, the target systems do not work on the other two tanks. In addition, the style of target system leaves a 2” wide open hole in the top of the tank which does not meet EPA/NMED sanitary requirements.

• Tanks #1 and #2 have a slight lean with a plumbness of 0.005” horizontal per 1” vertical (1/200) and

0.01” (1/100), respectively. Tank 3 has no measurable lean. The AWWA maximum allowed out of plumbness is 1/200 (0.005”) so Tanks 1 and 3 are compliant, while Tank 2 does not meet the standard.

• Site security was minimal as there is no perimeter fence. Fresh graffiti was observed on some of the tanks.

• Roadway access is very poor and will require proper grading, compaction, and application of basecourse or gravel at a minimum in order to provide access for rehabilitation activities.

As part of D&R Tanks inspection, ultrasonic thickness measurements were taken on the roof, floor, and shell plates. This data is included in Table 1. Minimum thickness measurements from the floors of Tanks #2 and #3 show that approximately 30% of the original metal thickness is gone in some areas. This is consistent with the holes found in the floors of all three tanks that were repaired prior to putting the tanks back in service.

Tank #1 (South), Elephant Butte, NM

P a g e 1 | 6

Tank #1 (South)

P a g e 2 | 6

Tank #1 (South): 16” Roof hatch only secured with two bolts/ nuts and no sealing gasket.

Tank #1 (South): Exterior ladder in good condition and target level system (non-functional).

P a g e 3 | 6

Tank #1 (South): Interior ladder corrosion.

Tank #1 (South): Interior ladder and roof hatch.

Notice light around roof hatch and target level gauge indicating poor sanitary seal.

P a g e 4 | 6

Tank #1 (South): New 30” manway.

Tank #1 (South): Target level system connection to tank.

Notice 2” diameter unsealed hole.

P a g e 5 | 6

Tank #1 (South): Close up of 2” diameter hole at target level system connection.

Tank #1 (South): Floor in poor condition.

P a g e 6 | 6

Tank #1 (South): 6” of sludge found at bottom of all tanks.

Tank #1 (South): Cleaned floor of tank.

Tank #2 (Middle), Elephant Butte NM

P a g e 1 | 5

Tank #2 and Tank #3 (North) Tank #2 (Middle): New 30” manway.

P a g e 2 | 5

Tank #2 (Middle) and Tank #3 (North) with graffiti.

Tank #2 (Middle): 16” roof hatch only secured with one bolt/nut and no gasket.

P a g e 3 | 5

Tank #2 (Middle): Interior ladder in poor condition.

Tank #2 (Middle): 6” of sludge found at bottom of tank.

P a g e 4 | 5

Tank #2 (Middle): Roof and interior ladder.

Notice light at target level gauge connection indicating a poor sanitary seal.

Tank #2 (Middle): Interior floor in poor

P a g e 5 | 5

Tank #2 (Middle): Interior floor in poor condition.

Tank #2 (Middle): Interior shell condition is good.

Tank #3 (North), Elephant Butte NM

P a g e 1 | 4

Tank #3 (North): New 30” manway. Tank #3 (North): Exterior ladder in good condition and target level gauge (non-functional).

P a g e 2 | 4

Tank #3 (North): Overflow Tank #3 (North): Roof hatch secured with one bolt/ nut and no gasket.

P a g e 3 | 4

Tank #3 (North): Interior ladder and roof.

Tank #3 (North): Floor in poor

P a g e 4 | 4

Tank #3 (North): Hole in floor. Tank #3 (North): Floor in poor