Hot Springs Tailings Dam Reclamation
Client: URS/Confidential Client
CTI provided a unique combination of highly experienced project managers, geotechnical and civil engineers, construction managers and trade labor to complete the final phase of the reclamation of a tailings dam. The work completed during this final phase included: mobilization and preparatory work, maintenance and control of traffic, haul road improvement/reinforcement and maintenance, demolition and removal, erosion and sediment control, site clearing, excavation, fill placement and grading, stream restoration, landfill cap construction, aggregate base placement, and permanent seeding. CTI set up trailer compound and equipment/material staging area and dewatered/stabilized a 10-acre pond. CTI prepared a traffic control plan, installed and maintained onsite and offsite traffic signage and barricades, and used full-time flaggers and spotters on haul routes at all times.
The haul road improvement and maintenance included repairing and maintaining over 80,000SF of haul roads including import/placement of structural fill and aggregate base to improve and maintain condition of haul roads. Demolition, removal, and abandonment of various drainage and erosion control features included abandonment/grouting of drainage pipes with approximately 150 CY of flowable fill. Erosion and sediment control included installation and maintenance of silt fencing, straw bales, rip rap, and Geoweb erosion control features and a rumble grid at site exit / highway entrance. CTI cleared and grubbed over 2 acres.Scope included excavation and relocation of pond sediments to ensure imported fill materials met site specifications for soil compaction. Fill and Grading included importing and placing 140,000 CY of random fill, sand, and select fill in tailings pond to complete cap over 60-acre tailings pond.CTI constructed nearly 6 acres of landfill cap which included construction management of the PVC liner installation.
Stream Restoration involved excavation and reconstruction of a 500 LF rip- rap lined drainage channel and construction of a 1300 LF PVC-lined diversion channel for sediment control. CTI imported and placed approximately 500 tons of aggregate base for site roads. CTI furnished and incorporated 10 tons of agricultural lime, fertilizer, seed, mulch, and jute matting erosion control blanket over 10 acres. CTI’s management team consisting of a Construction Manager, Site Safety Manager, and Quality Control Manager implemented a behavioral-based safety program and CTI’s construction team of heavy equipment operators, truck drivers, construction laborers, quality control, and testing personnel who worked diligently through various weather delays, changing soil material properties and demanding safety conditions and quality assurance requirements to deliver a successful project.
The primary challenges associated with this site included:
(1) client designation as a “Challenged Safety Site” due to the performance of previous contractors;
(2) heavy construction traffic load; and
(3) storm water management.
These challenges were addressed and overcome in the following ways: Screening of subcontractors and gaining client approval prior to entering into all subcontract agreements to ensure safety culture similar to the client’s and CTI’s. Site-specific training for all site personnel including subcontractors and truckers to ensure heightened awareness. Daily safety meetings and more frequently when necessary. Every employee working on the jobsite, including subcontractor’s personnel, prepared a Safety Task Analysis Card (STAC) prior at the beginning of every shift, and revised the STAC during each shift whenever job assignment changed. CTI’s upper management participated in bi-weekly safety calls with client’s management team to discuss effectiveness of safety program and to identify additional measures when required. CTI imported and placed over 2000 CY per shift which resulted in an average of one haul truck entering the site every 3 minutes. Additionally, vehicles driven by the facility owner’s personnel, the client’s personnel, CTI’s personnel, subcontractors, and vendors/suppliers added to the heavy traffic load.
Due to site constraints, haul roads could only handle one-way traffic in various locations and had a number of blind spots in the roadway. CTI managed this challenge by installing onsite and offsite traffic signage, providing full-time flaggers at areas limited to one lane but requiring two-way traffic and to manage traffic at blind spots, and providing dedicated spotters at each dumping location. The project was performed in a 10-acre pond that received surface drainage from a 60-acre cap which was constructed during an earlier construction phase. In order to manage the storm water, CTI constructed a 30-mil PVC lined diversion ditch to divert storm water around the work site. CTI also used dedicated pumps for dewatering and managed storm water 7-days per week, 24-hours per day when necessary.