The treatment of nitrogen is one of the key elements in maintaining compliance with the TMWRF Discharge Permit.  The majority of nitrogen enters the treatment plant as ammonia.  In order to remove the ammonia, it must first be converted to nitrate.  This reaction occurs in the nitrification towers where ammonia is biologically converted to nitrate.  Four of the six nitrification towers at TMWRF were constructed in 1985 and have been in continuous service since.  The towers are filled with a honeycomb plastic media which serves as a surface for the microbes to grow.  A rotating sprinkler at the top of the tower spreads the wastewater across the media where it flows by gravity across the microbes to the bottom of the tower.  The plastic media as well as the sprinkler are original equipment and are at the end of their service life.  Additionally, seams in the concrete walls of the tower are failing and need to be replaced.  This rehabilitation project will replace all of the media, the sprinkler mechanism and make necessary structural repairs to the tower.

Complicating the construction is the need to have the nitrification tower back in service prior to the colder winter months when the nitrification reaction is less efficient.  In order to ensure the timely completion of the project the contract requires the contractor to procure all necessary materials prior to the beginning of the removal of the existing media.  With an expected lead time of 6 months for the volume of media needed, the contract anticipates procurement of materials during the remainder of 2019 with construction beginning as soon as practicable in 2020 depending on the weather. 

The City of Reno held an open, competitive bid for this project with bids being opened on March 27, 2019.  K.G. Walters Construction Co., Inc.  submitted the lowest responsive bid.  The current Capital Improvement Plan budget approved by the TMWRF Joint Coordinating Committee for the construction of this project will support the award of the bid in the amount of $4,298,500, with the City of Sparks’ share $1,348,439.45.  

1. City Council can approve the reimbursement as presented by staff
2. City Council could direct the City Manager to have staff explore other options.

I move to approve reimbursement to the City of Reno for Sparks’ share of a construction contract (AC-5568)  with KG Walters Construction Co. Inc. for the Nitrification Tower 2 - 2019 Rehabilitation Project at the Truckee Meadows Water Reclamation Facility in the amount of $1,348,439.45.