A Sanitary Sewer Evaluation Survey and Infiltration & Inflow (I&I) Study was completed by the City in December 2009, as an aid in identifying areas that are experiencing or may experience high volumes of I&I.  Infiltration is groundwater/storm water that can enter sanitary sewer systems through defective pipe joints and/or broken pipes typically found below the surface. Inflow is water entering the sanitary sewer system from inappropriate connections such as roof drains, yard drains, and domestic sewer cleanouts without caps located on private property. Both of these undesired water sources can be identified through sanitary sewer smoke testing. High volumes of I&I can cause dilution in sanitary sewers which can decrease the efficiency of wastewater treatment or may cause sewer volumes to exceed wastewater treatment plants’ capacities. Many times it may be difficult to distinguish the source of the cause, so the Environmental Protection Agency (EPA) defines the term I&I as combined contributions from both.

This process prioritized the lift station infrastructure and service areas for further investigation.  The study included a GIS-based rating system to identify critical line segments based on factors such as infrastructure needing repairs, pipe depth and material. The recommended improvements were ordered and ranked by importance based on the GIS risk rating system, with Project A being the higher priority and Project D being a lower priority.  Rehabilitation efforts for Project A, B and C have been completed.

Project D is identified as the next priority focus. A Preliminary Engineering Report (PER) for Project D was completed in April 2017. The construction of Project D is separated into two packages due to different construction means and methods required.  Package 1 involved cured-in-place and Package 2 requires pipe bursting to rehab the identified wastewater lines.  The design for Package 1 was completed in April 2018 and construction is currently underway. The design for Package 2 was completed in July 2018 and is now ready for construction. 

An Invitation for Bid (ITB) was advertised for Package 2 on August 1, 2018 and August 8, 2018.  Bids were opened on August 23, 2018 and six (6) bids were received for the project.  The following is the bid summary:

The responsible low bidder is T Construction, LLC with a total bid of $631,415.  The Engineer's estimate of probable construction cost is $620,000. The Consultant along with City staff recommends awarding the contract to the responsible low bidder, T Construction LLC.

The construction scope of work for Project D Package 2 is summarized as follows:

• Rehabilitation of approximately 11,125 L.F. of 6-inch to 15-inch by pipe bursting method
• Rehabilitation of manholes with coatings
• Television inspection
• Service reconnections

There is currently $706,104 available in CIP WW1601.  The remaining project balance will be used for a construction administration contract and construction contingency.

Construction of Package 2 is anticipated to begin in October 2018 with 180 calendar days to substantial completion in March 2019.  The City is aware of the potential impacts to residents and will coordinate and communicate as required per City notification policy CO-0110, Construction Notifications.  Staff and the contractor will utilize several measures during construction such as door to door visits, door hangers, mail outs, and website updates in order to maintain open communication with all impacted property owners. 

Staff recommends the City Council authorize the execution of a construction contract with T Construction, LLC in the amount of $631,415 for the Wastewater Collection System Rehabilitation Project D, Package 2, CIP WW1601.