Public Works staff has obtained sulfate and hydrogen sulfide (H2S) samples at various points in the sewer system. The laboratory analysis of the samples shows higher than anticipated levels of both sulfate and H2S in many locations. The presence of H2S in sewer systems has been shown to be a safety hazard and increase corrosion, which reduces the lifespan of wastewater infrastructure. This plan will develop a sewer model that predicts sulfate and H2S concentrations and subsequently develops alternatives to mitigate the effects of H2S in the sewer system.

City Council may:

• Award the Contract for Professional Services to HDR Engineering, Inc., or
• Do not award the contract.  If the contract is not awarded, the safety of Public Works staff will be compromised and increased corrosion in wastewater infrastructure will result in higher costs for rate payers.

There is available funding in the Wastewater FY19 Capital Improvement Projects.

Staff recommends that Council authorize the Mayor to execute a Contract for Professional Services with HDR Engineering, Inc. for $167,145.00 for Work Order 19-05 – Wastewater Collection System Hydrogen Sulfide Mitigation Plan.