The City of Houston has spearheaded the Northgate Regional Lift Station project as part of its plan to reduce operational and maintenance costs by consolidating 39 wastewater treatment plants and more than 380 lift station facilities. As a result, the project will decommission the Imperial Valley Wastewater Treatment Plan, which handles 4 million gallons of water per day.

As part of the Northgate project, Stiver Engineering successfully delivered to the contractor an expedited alternate design for a 70-foot-deep caisson. Stiver performed a detailed finite element analysis, and the structure was checked against various load cases. We designed the outer shell along with the interior partition wall, bottom slab and the top slab.

The design was performed and checked for each phase of construction, including casting, sinking, and installing the bottom slab, the partition wall and the top slab. Each condition was analyzed and optimized to provide the field crews with a more normalized rebar pattern and installation procedure.

The city of Conroe, Texas, is building a $60 million Central Wastewater Treatment Plant that will be designed to handle up to 12 million gallons per day. Stiver Engineering provided design services for a 38-foot ID Lift Station for the new Central Wastewater Treatment Plant in Conroe, Texas. Our work included sinking calculations and the finite element analysis of the exterior walls and the caisson bottom slab.

Stiver Engineering prepared a caisson cutting edge design for a wastewater lift station replacement project in Redmond, Washington. In addition to the caisson cutting edge design, Stiver performed skin friction calculations for the pour heights and proposed wall thickness to check the safety factor for sinking.

Division 1 of this Project consists of, but is not limited to, the following: raw water pump station including passive intake screen, intake line, wetwell, two (2) vertical turbine pumps and space for a third pump, bridge crane, and potassium permanganate feed system; cast-in-place concrete 2.5 MGD pretreatment facilities including two-stage rapid mix, two-stage flocculation, high rate sedimentation using plate settlers, and hoseless sludge collectors; 2.5 MGD (expandable to 5.0 MGD membrane filtration facility including membrane filtration treatment modules, CIP system, neutralization system, onsite hypochlorite generation system, chemical feed systems, control room, lab, restrooms, locker room, offices, break room, finished water pumping facilities (two (2) vertical turbine pumps and space for a third pump); finished water storage consisting of a 75-foot-diameter by 30-foot tall 1.0-MG pre-stressed concrete storage tank; plant control system (PCS) consisting of field mounted instruments and control devices, non-proprietary distributed control system utilizing personal computers (PCs) and programmable logic controllers (PLCs); all related site work, piping, electrical, and any other activities incidental to the completion of this Project. Division 2 of this Project consists of, but is not limited to, approximately 8,975 linear feet of 20-inch ductile iron raw water transmission main from the new Lake Hartwell Raw Water Intake on Durham Road to the existing 20-inch main on South Carolina State Highway 59 near the intersection with Fair Play Boulevard in Fair Play, South Carolina, including all related equipment and appurtenances, connections to existing waterlines and facilities, erosion control, grassing, and any other activities incidental to the completion of this Project. No additional specifications were given.

Stiver Engineering was retained by the contractor to provide structural engineering services for the design of the caisson (raw water pump station).  The caisson is 16 ft. diameter by 50 ft. deep.  The contractor successfully sunk the caisson in wet sand.  Stiver Engineering designed the reinforced concrete caisson to be sunk and sealed underwater.  This is a technique that we spent many years learning from working with contractors while sinking caissons in the saturated sandy soils of South Texas.

Stiver Engineering was retained by the client in Texas City, Texas to provide structural design through a caisson design and a 36-inch diameter force main design. The structure was built above grade with excavation of the inside soil, and it was allowed to sink to finish grade. The project included twin natural gas standby generators and a 36-inch diameter force main.