The water flow of industrial and potable underground water wells typically decreases over time. One of the main reasons for the decline in water productivity is the accumulation of hard water scale, biofilm, clay, and iron oxide deposits. The contaminants block the water flow causing gradual damage to the water-producing well formation.
Glycolic acid is one of the top solutions for well rehabilitation and flow stimulation. It provides superior cleaning efficacy for hard water scale (calcium, magnesium, manganese salts), various iron deposits, polysaccharide deposits, and biological film formations.
Why Glycolic Acid for Water Well Rehabilitation:
NSF certified for the cleaning of potable water wells
Chelates hard water metal salts by forming water-soluble compounds that are easily rinsed away
Very low corrosion to the metal parts of the well compared to mineral acids
Biodegradable, low toxicity, low odor, non-flammable, and negligible fumes
Compatible with other acids. Can be used in blends to improve cost and effectiveness
Excellent removal for polysaccharide and common organic deposits
How to use Glycolic Acid for the stimulation of water wells and increase water productivity
The Pretreatment Steps of Well Stimulation:
Measure the water flow and compare it with historical flows to determine the flow deterioration over time and set a goal for when the cleaning procedure is required. The flow typically deteriorates because of gradual damages to the well formation, accumulation of deposits, or mechanical damage to the down-hole filter system.
If iron bacteria is present, the well will need a shock treatment with chlorine to loosen the bio-slimes and organic biofilm deposits.
Apply a high-frequency shock to loosed the scale through denoting blasting caps in the water wellbore.
Purge the well and check for large amounts of rock and gravel that can indicate a problem with the screen or the gravel pack. If a mechanical issue is present, it needs to be fixed before the cleaning procedure.
Measure the water pH to determine the required amount of Glycolic acid for the cleaning procedure.
The Application Steps of Well Rehabilitation:
Determine the Required Amount of Glycolic Acid:
Add Glycolic acid 70% solution tech at a rate of 1/2 gallon/ ft³ standing in the wellbore. This should give about a 5% concentration of the acid in the water. The acid can also be pre-mixed with water in a preparation tank if needed.
Example: A well with a diameter of 10" and 126 ft deep with a static water level of 30 ft below the surface. This well would require (126 – 30 ft) x 0.241 = 23.1 gal of glycolic acid 70% solution.
Diameter of Well, in.
Gallons of Glycolic Acid, 70%, to add per
foot of water to give a 5% (wt) solution
The Cleaning Procedure:
Add the determined amount of glycolic acid solution and surge the well to facilitate the mixing and to allow the acid to penetrate into the well formation. Dislodge scale by starting and stopping the pump every 3 - 4 hours. You can also drop a large plug into the wellbore if surging the water column is not applicable. It is recommended to allow Glycolic acid in the well for at least 24 hrs or more.
Removal of the Cleaning Solution
Pump the water to a location (ground or biological treatment facility) in conformance with local environmental regulations. To facilitate the suspension of solid matter, purge the well slowly at first and then at about 25% of full flow. Also, At 15 - 30 min intervals, stop the pump long enough to allow the well to drop to its static level.
Flushing and Finalizing the Cleaning Procedure
Continue pumping the water until the pH is within 0.5 of the original pretreatment value. This will typically take about 1 - 3 hrs. from the start of the flushing procedure. Repeat the above steps as necessary if the water flow is not fully restored.