ADMINISTRATION - Jon Haukaas, Director of Public Works
Title
AUTHORIZE THE MAYOR AND CITY MANAGER TO ENTER INTO A PROFESSIONAL SERVICES CONTRACT WITH DONAHUE ENGINEERING TO INVESTIGATE CORROSION ISSUES
Background
Well No. 3 failed in the spring of 2018 requiring an emergency repair. Investigation of the adjacent Well No. 4 revealed similar corrosion issues and is currently being repaired. Staff is concerned that the corrosion may be a result of a galvanic reaction of the steel piping induced by the stray electrical currents from nearby utility lines in TH65 and US10. Water Tower 1 and Water Treatment Plant 1 are also located near these wells in Aquatore Park. Tower 1 was originally designed with a Cathodic Protection system but was later removed during a renovation project in the early 1990s.
Galvanic corrosion is an electrochemical process in which one metal corrodes preferentially (our steel pipes) when it is in electrical contact with another in the presence of an electrolyte. The other metal is the surrounding soils and protected gas pipelines in TH65 or US10. Flowing liquids can create an induced electrical current in the ground. The electrolyte is the groundwater. All four facilities are interconnected and may be affected by on-going corrosion.
Current Work Proposal
The scope of work includes investigation of the root cause of corrosion at the two wells, and then design a mitigation method if warranted. A simple sacrificial anode may be the ultimate solution to provide Cathodic Protection of our system once again. This work will make that determination and how extensive that system will need to be.
Financial Impact
The engineering services under this proposal are estimated at a cost of $22,000. Funds will come from the Water Enterprise Funds.
Future Work
The determined improvements will be bid out separately at a future date.
Recommendation
By motion authorize the Mayor and City Manager to enter into a contract with Donahue Engineer to investigate water system corrosion issues in the amount of $22,000.