Cost function filter back-washing by pumping:

The original cost function (A1) for filter back-washing by pumping is the following:

This has as a variable (x) that represents the pumping capacity in gpm (gallons per minute) which will be the same as the plant. The conversion to L / s is carried out and the following is obtained:

+

Additional modifications to this function correspond to the correction of costs per year, with the CCI ENR index of 9547 of the year 2013, to obtain A3. Then the part B2 related to the elasticity index is added. This is done in the same way as explained in the Cost Functions Wiki — General.

With this, the following is the function obtained:


Bibliography

Preliminary Cost Estimation Models for Construction, Operation, and Maintenance of Water Treatment Plants. 2013. Jwala R. Sharma, Ph.D., M.ASCE; Mohammad Najafi, Ph.D., P.E., F.ASCE; and Syed R. Qasim, Ph.D., P.E., M.ASCE. | https://ascelibrary.org/doi/abs/10.1061/%28ASCE%29IS.1943-555X.0000155

Referencies

What is filter backwashing? | https://www.oregon.gov/oha/PH/HEALTHYENVIRONMENTS/DRINKINGWATER/OPERATIONS/TREATMENT/Documents/Backwash.pdf