Back to Last Page Visited
Navigation Bar Skip Navigation City Council Contact Us Search City Government
Department Contact
Back to our Homepage

Sanitary Sewer Surcharges

The City of Longmont’s Wastewater Treatment Facility was designed to treat domestic sewage. Strong wastestreams cost more to treat because of the increased pollutant load. The sewer surcharge provisions in the City Ordinance were created to achieve equity between treatment costs and charges for all users. Please refer to sections 14.08.650 and 14.08.665 of the Longmont Municipal Code for further information.

IP Program


501 East 1st Avenue

Longmont, CO 80501

Phone (303) 651-8667

or email



Surcharge rates effective January 1st available on-line.

Pollutants of Concern: Biochemical Oxygen Demand (BOD), Total Suspended Solids (TSS) and Total Kjeldahl Nitrogen (TKN)

These are conventional pollutants, meaning that they are part of normal domestic wastewater. They are treatable by the wastewater treatment plant. However, commercial and industrial dischargers can discharge wastewater with higher loadings than domestic users and must compensate the City for the additional treatment requirements.

How is the Sewer Surcharge Billed?

Industrial users are billed separately by the IP Program.

NEW-Beginning in 2013, commercial users will no longer be charged the "BOD Surcharge" item on their utility bill.

How is the Sewer Surcharge Calculated?

Industrial users are required to report wastewater volume and pollutant concentrations. The surcharge is calculated for the portion of the loading above the domestic values.

Domestic values: BOD = 300 mg/L, TSS = 330 mg/L and TKN = 45 mg/L. These values are based on samples collected from Longmont sewers serving only domestic users.

Costs of treatment per pound: Current surcharge rates available on-line.

Calculation for surcharge on pollutant:

Surcharge $ = Total Flow, MGD x (pollutant, mg/L - domestic value for pollutant, mg/L) x 8.34 x $/lb

Example: A company has a large tote of old syrup and wants permission to discharge it to the sewer. A waste hauler wants to charge them $500 for disposal. Is it cheaper to pay for disposal or treatment? The company reports that the tote is 1,000 gallons. Samples were analyzed and found to be 100,000 mg/L BOD, 25,000 mg/L TSS and 13.5 mg/L TKN.

The IP Program would be considered a compatible waste that could be treated by the wastewater treatment plant, assuming the discharge does not cause a sewer blockage. Costs of treatment can be calculated:

(1,000 gallons/1,000,000) x (100,000 mg/L - 300 mg/L) x x8.34 x $0.36/lb = $299.34 for BOD
(1,000 gallons/1,000,000) x (25,000 mg/L - 330 mg/L) x x8.34 x $0.32/lb = $65.84 for TSS
(1,000 gallons/1,000,000) x (13.5 mg/L - 45 mg/L) x x8.34 x $0.15/lb = $0 for TKN (Because it is lower than domestic value)

Sum =$365.18

Treatment of the waste is less than the hauler's price, but the company should consider other options like recycling or reuse.

Back to top.


Pollution Prevention|Industrial Pretreatment Program|Wastewater Treatment |Public Works & Natural Resources|City of Longmont


This page was updated August 16, 2013
City of Longmont Public Works & Natural Resources
Industrial Pretreatment Program