BHC Consultants 5/1/2026 - Laserfiche WebLink

Exhibit A (Scope of Work) SCOPE OF WORK EXHIBIT A SCOPE OF SERVICES Background The City of Everett, Washington (City) has selected BHC Consultants, LLC (BHC) to provide engineering services for the WPCF TFI Bar Screen Pipe Repair Project. The City issued a notice-to-proceed letter dated January 21, 2026 to get BHC started immediately on this work with the understanding that a professional services agreement would be prepared and executed in parallel with the work and work completed prior to execution of the agreement would be paid on a time and materials basis. The City recently completed the construction of a bypass pipeline for the TFI bar screen that involved connecting a new 36-inch bypass pipeline between existing Diversion Structure No. 2 and a new junction vault installed along the 48-inch trickling filter influent (TFI) pipeline. Since completion of this project, the City has noticed settling in the area that had been excavated for installation of the bypass pipeline and junction vault and substantial rapid settling around the southeast side of the recirculation/bypass flow control structure where the 48-inch TFI pipeline exits the structure. On further investigation, the City noticed that the 48-inch TFI pipeline has separated from the structure. In addition to this, an existing coupling located downstream of the 90-degree elbow has separated from one end along the 48-inch secondary effluent (SE) pipeline exiting the southeast side of the Recirculation/Bypass Flow Control Structure. It is believed these separations induced scouring from the exiting water that created a significant void leading to the recent rapid settling. The initial settling might be due to heavier backfill, soil freezing utilized for excavation, and/or insufficient compaction. The City utilized a third party testing firm to perform compaction tests during construction, so presumably sufficient compaction was achieved. Due to the number of pipes and conduits in the excavated area, soil freezing was utilized for both shoring and groundwater control, which avoided the complication of placing sheet piles in the congested area and settling induced by removal of groundwater. Freezing the soil does cause some expansion (heave), but this did not appear to be a significant problem during construction. Some heaving was noticed at the existing 48-inch TFI pipe, primarily due to wetting of the frozen soil from rain, but this was kept to a relative minimum by keeping the area covered to maintain the soil as dry as possible. The design originally included hog fuel as part of the backfill to reduce the net weight of the backfill to be approximately equal to that of the soils removed. Although the hog fuel would have only be used in the lower portion of the excavation that should normally be below the groundwater table, the City was still concerned about potential for settlement due to degradation of the hog fuel and so desired to instead use all gravel borrow for backfill between the pipe bedding and asphalt subbase material, which resulted in a net weight exceeding the in situ soils. Although the weight of the bypass junction box, even filled with water, is less than the weight of the native soils removed, heavier backfill could also induce settling of this structure by acting upon the base extending out from the sides of the structure (needed to prevent uplift if the structure is empty) and inducing settling in adjacent soils. This project involves the design of emergency repairs to the leaking 48-inch TFI pipeline at the TFI bar screen structure and separation of the existing coupling along the 48-inch SE pipeline, as well as replacing the TFI bar screen dumpster pad and resetting an existing electrical vault that were undermined by the settling and restoring grade and the asphalt surfacing in the