Aztec WWTP General Improvements, Aztec, NM
After engineering the new wastewater treatment plant, which cost $8.4 million, to meet new, more stringent EPA guidelines Smith provided construction management services throughout construction. The Aztec plant is a course bubble aerated and mixed system in the extended aeration regime, with advanced nutrient removal tertiary treatment. The original design was to have only the top three feet of the secondary and advance treatment basins' walls above grade. After construction commenced, the contractor encountered technical difficulties with the dewatering and shoring that would significantly increase the cost of construction. Smith engineers and technicians were on-site to observe the subsurface conditions first hand. After performing a cost analysis of several options, Smith redesigned the plant basins to be raised 9.67 feet, with the associated changes in piping. The above grade redesign, as a result, required a 9.0 MGD lift station to account for peak flows. Working with the City, the Contractor, and the suppliers, Smith completed the redesign in three weeks, causing no delays in the construction schedule and a reduction in the construction cost.
Because of the plant's use of innovative technology, simplicity of operation, and low cost it was recognized in 2010 as the "NM Project of the Year" by the American Public Works Association and for its "Engineering Excellence in NM" by the American Council of Engineering Companies.
Artesia WWTP, General Improvements, City of Artesia, NM
The Artesia plant is a high-performance oxidation oval operating in the extended aeration regime of activated sludge. Shortly after construction began a grade bust was noted when subsurface piping was exposed. The bust caused the main aeration and clarifying structures to be several feet too high. Inaccurate record drawings of the existing facility caused the error. Smith field technicians and engineering staff were able to issue modified plans, to adjust for the error, within two weeks. Construction continued uninterrupted and there was no additional construction cost.
Smith is currently providing construction management and materials testing for the Artesia WWTP. The project is currently housing a full-time construction observer and testing technician. Special inspections have been concrete reinforcement bolting, welding, and leakage tests. Materials Testing has included: soil, aggregate, and concrete testing in the field and the laboratory.
The Deming plant is a pond-based system with nitrifying biotowers (trickling filters). The ponds were lined with synthetic fabric on the bottoms and concrete on the sides. During sludge removal the synthetic bottoms were damaged and wastewater escaped into the underlying soils. Gases produced by bacteria in the wetted soils under the reactor pond caused bubbles that lifted the liner into the mechanical aerator's mixing streams. Smith Engineering technicians suggested emergency operational changes in the field. Our engineers quickly designed and specified a concrete protected/weighted synthetic liner replacement. The reactor pond was emptied, relined, and placed back online within 6 weeks.