Construction Dewatering Water Treatment Tips

In many cases when you have to dewater an area of a construction or remediation site to do an excavation or other subsurface work, the water is clean and can be easily discharged without treatment. However, in some cases, the soil and groundwater are contaminated, and if dewatering is required, it is highly likely that the discharge water will be contaminated and will require some type of treatment prior to discharge. If you think this may be required on your next job, it is important to do some planning for a temporary water treatment systems and the associated costs.

To accurately design and estimate the cost of a reliable temporary groundwater treatment system, you need to gather the right data. This can save you lots of money and headaches when you actually go to the field.

Ideally, the following questions should be answered:

  1. What is the actual flow rate that will need to be treated?
  2. Will the flow be continuous or intermittent?
  3. What is the estimated duration of the project?
  4. What are the estimated actual influent concentrations of the contaminants in the water?
  5. What are the discharge requirements in your discharge permit?
  6. What are the water quality data for the site’s groundwater including pH, alkalinity, turbidity, total suspended solids (TSS), hardness, iron & manganese concentrations, chloride, sulfate, conductivity, total dissolved solids (TDS), total organic carbon (TOC) and oil and grease.
  7. If metals are present in the groundwater, what are the total and dissolved concentrations? Methods of treating water for dissolved vs solids borne metals vary significantly.

Require that the company you consider for providing the water treatment equipment provides you with a basis for their design in the form of calculations or modeling. This establishes a solid basis for their design and can be very helpful in securing a discharge permit.

Allow for a pilot test, if recommended by the water treatment equipment supplier. It will require additional work up front but can save a great deal of money by getting the water treatment design right for your site. In many cases, this is the only way to get an accurate estimate of influent concentrations and to prove that a process will work with the specific water at your site, particularly if inorganic contaminants (metals) are involved.

Ensure that your project plan allows for enough space on the job site to house the water treatment system in a location that makes sense.
Leave the solids in the hole. Suspended solids are the enemy! Always use a screened well point or some other filtered recovery source for the dewatering system. Heavy solids loading can add significant costs to the water treatment process and it is always best to leave the solids in the ground whenever possible.

Questions? Contact us here.

Still need help, please contact Carbonair here, or call us at 1-800-526-4999. Important things to consider when you have to treat dewatering discharge water at your site. |

Sign Up for More Articles