REPORT TO CITY COUNCIL
To:Honorable Mayor and Members of the City Council
From:Jason Simpson, City Manager
Prepared by:Shannon Buckley, Assistant City Manager
Date:January 9, 2024
Subject:Public Works Agreement with Elliott Drilling Services, Inc. for the Site Grading of the New City Hall Project (CIP Project #Z20006) Recommendation
Approve and authorize the City Manager to execute a public works agreement with Elliott Drilling Services, Inc. in an amount not to exceed $398,500.00 for the site grading of the new City Hall Project (CIP Project #Z20006) in such final form as approved by the City Attorney and authorize the City Manager to execute change orders not exceeding a 10% contingency of $39,850.00 for construction uncertainties and adjustments.
Background
On October 10, 2023, the City Council awarded a demolition agreement for the five buildings on the new City Hall site. The City Council also awarded a grading site development agreement on November 14, 2023. On December 15, 2023, the demolition of the five buildings was completed, and the grading immediately began after that. During the demolition and initial site development excavation, city construction management staff discovered that the wall of the building adjacent to the existing City Hall building shared an underground structural footing. Essentially, this footing supported both buildings and cannot be separated without shoring support. Half this footing must be removed from the building site to accommodate the new underground structural support.
Failing to prevent the adjacent soil from collapsing into the excavated area would impair the existing City Hall's structural integrity and create an unsafe work area within the new City Hall site.
City Hall Site Grading Agreement
Discussion
Given this potentially imminent hazardous situation and the need for a highly specialized contractor that could act quickly, a time-consuming bid process was deemed adverse to the City's public safety concerns. City staff immediately sought input from a contractor with significant experience and the workforce to take immediate remedial steps. Unfortunately, sufficient room around the perimeter of the building footprint does not exist, so conventional benching and sloping are not suitable solutions. The property limit setbacks are very narrow.
To fortify the existing City Hall building wall adjacent to the new City Hall and to create a safe, deep foundation work area, an expedited shoring design has been engineered. Shoring must be established in conjunction with excavation operations to maintain work progress safely.
Elliott Drilling Services Inc. has completed a work order and proposal to design and construct the shoring. This design/construct shoring plan will ensure the structural integrity of the existing City Hall building and provide safety elements throughout the site development, where excavation of new footings will reach depths of up to 13+ feet in restrictive areas around the site perimeter.
The deliverables in this agreement will include the following significant elements designed to ensure the continued structural integrity of the existing City Hall and provide for a safe work area for the new City Hall construction:
•Design Temporary cantilevered shoring and backside of beam lagging inside p/l for beams #1-#30.
•Furnish and install 472LF of 5ft-14ft max support beam and lagged temporary shoring for over-ex. Lagging placed on p/l. for beams#1-#46.
•Drill all soldier pile locations with proper drill rig access supplied by others. Elliott will confirm access and approach w/ the general contractor.
•Drill all soldier pile shafts.
•Furnish and install steel soldier piles into drilled shafts. •Furnish and install lean and structural concrete into drilled shafts. •Stockpile drilled and lagging spoils adjacent to each work area for removal by others. •Furnish and install timber lagging (3") along p/l to the bottom of over-ex elevations and compact soils behind lagging.
•Trim beam tops to 24" below grade.
•OSHA Notification.
•Dig Alert Notification.
•Prevailing wages.
Environmental Consideration
Approval of the agreement for grading is in furtherance of implementing the City Hall project approved by the City Council on May 10, 2022. Additionally, there is no substantial change to the project's new circumstances under which the project will be developed. Accordingly, no further environmental review is required.
City Hall Site Grading Agreement
Fiscal Impact
Funding costs are included in the Fiscal Year 23/24 – 27/28 Capital Improvement Plan (CIP) budget, CIP Project #Z20006.
Attachments
Attachment 1 - Agreement
Exhibit A - Proposal