Contra Costa Canal Hydraulic Study, Contra Costa Water District, Concord, CA
Dr. Lewandowski performed a hydraulic study of the Contra Costa Canal to identify the current channel capacity and potential for flow constraints at channel siphons and check structures. The study included analysis of the unsteady flow in the tidally influence earth lined canal section, and the steady flow capacity in the concrete lined sections downstream of Pumping Plant 1 using HEC-RAS. Field tests were done to determine the Manning’s n value for the concrete lined sections and culverts in the earth lined sections. A post performance tool was developed to summarize the results of the modeling and to provide a graphical comparison of canal capacity with expected flow delivery rates through 2050.
South Bay Aqueduct (SBA) Hydraulic Capacity Study, Zone 7 Water Agency, Alameda County, CA
Dr. Lewandowski assisted the Zone 7 Water Agency in Alameda County with a hydraulic analysis of the existing South Bay Aqueduct as part of the raw water conveyance study. This work determined the design capacity, current capacity, and necessary modifications to the aqueduct to provide adequate capacity for future additional flows. Hydraulic testing was performed on portions of the canals and piping of the SBA to determine current head loss conditions. The backwater conditions measured in each canal section were used to determine the current Manning’s n values for the canal sections. Reviewing operating records of the SBA, he determined that Manning n values of the concrete lined channel were forty percent higher than design values. He assisted in development of alternatives to increase the aqueduct capacity, including replacement and paralleling of pipelines, raising the canal lining, relining pipelines to reduce the friction factor, and increasing the operating head.
Hydraulic Analysis of the Upper Diamond Fork Project, Central Utah Water Conservancy District
Dr. Lewandowski performed hydraulic calculations and assisted with the hydraulics design report. This design-build project included a flow transition connection to an existing 660 cfs flow discharge structure; a vertical 600 foot, six foot diameter shaft discharging to an underground flow control chamber; a five mile length, 10.5 foot diameter tunnel with an access and overflow structure; and 4000 feet of 96-inch diameter pipe. Challenging hydraulic situations included side flows over weirs, a channel transition from the tunnel to a rectangular channel that created supercritical flow, and a hydraulic jump forced by a drop in channel bottom elevation at the overflow structure.
Collier Canyon Creek CLOMR, Livermore, CA
A storm water bypass consisting of parallel 72 inch diameter and 78 inch diameter pipelines was constructed for the Collier Canyon Creek in North Livermore. Dr. Lewandowski developed models for both the creek and the bypass pipelines for use in development of a CLOMR for the project. Channel flows were reduced by the bypass, causing the 100-year floodplain boundary to lie within the channel banks. The pipelines flows were modeled using PCSWMM, which allowed for partially full pipeline flow in the steeper lengths of the parallel pipes. The natural creek channel was modeled using HEC-RAS, with flow boundary conditions developed on an iterative basis, depending on the flow rates in the bypass pipeline. Dr. Lewandowski worked directly with FEMA staff to finalize the modeling issues and resolve the CLOMR application issues.
Agua Fria Creek Relocation Analysis for Warren Avenue Grade Separation, Fremont, CA
Dr. Lewandowski was project manager for the hydraulic analysis of two large supercritical flow channels that were relocated to allow construction of a roadway undercrossing of a railroad right of way. Preliminary hydraulic calculations were performed to determine approximate slopes, channel widths, and superelevation at channel curves to prevent flooding at the 100-year flow rate. The channels were a combination of rectangular open channel and culvert flow. Transitions between the rectangular and existing trapezoidal channel and the junction of the two supercritical flows were designed to prevent formation of hydraulic jumps. A HEC-RAS model was developed to verify channel flow conditions and water surface profiles.
San Pablo and Wildcat Creeks Floodplain Assessment, San Pablo, CA
FEMA had proposed revisions to the City of San Pablo’s Flood Insurance Rate Map (FIRM) that included significantly greater flooding areas compared with previous mapping. The revised boundaries included a total of 340 acres in the floodplain, with an additional 1,200 homes included in the floodplain area. As project manager, Dr. Lewandowski reviewed the Preliminary FIRM boundaries and results of the HEC-2 and HEC-RAS models for both San Pablo Creek and Wildcat Creek prepared by FEMA. He also revised the models to include reductions in Manning’s n values, recent channel improvements and bridge modifications, and an updated topographic map with 2-foot contours. After the adjustments, the floodplain developed from the revised model included only 140 acres, a reduction of 60 percent from the preliminary FIRM values. He assisted the City with their appeal of the FEMA preliminary FIRM. The revisions have been accepted by FEMA and will be included in the future map.
LAVWMA System Capacity and Storage Assessment, Dublin, CA
Dr. Lewandowski served as project engineer for an analysis of the existing system capacity for the Livermore-Amador Valley Water Management Agency (LAVWMA). This project involved development of models for the existing wastewater treatment, storage and disposal systems to identify the limiting Average Dry Weather Flow (ADWF) that can be accommodated in the existing system. Three separate models were developed to show the limitations of storage operations at the treatment plants and at the pump station. He also developed an innovative methodology to determine maximum wastewater storage needs from a combination of collection system characteristics and the rainfall intensity curves for the area.
Drainage and Water Quality Studies for Los Angeles International Airport Expansion, Los Angeles, CA
These studies were completed as part of the CEQA/NEPA effort to determine impacts of the planned airport expansion. Dr. Lewandowski was project engineer for the drainage and water quality analyses. The potential for flooding created by the planned expansion was compared with the existing flooding at the airport. Alternatives were reviewed using existing airport facilities to mitigate increases in peak storm flow and storm water pollutants.
Hydraulic Analysis of Water Storage Tank Failure, Simi Valley, CA
For the Calleguas Municipal Water District in Simi Valley, CA, Dr. Lewandowski performed hydraulic calculations related to the catastrophic release of water from a 5 MG water storage tank. Earthquake failure scenarios were reviewed, to determine the potential variation in types of failure and consequent release of water from the tank, and potential safety issues for operators in the area. Possible flow paths and flood flow routing procedures were used to determine the flow rates leaving the site, and the flooding levels in relation to the operational areas and pumping equipment. Revisions in the yard design were proposed to reduce the peak flow leaving the site.
Filter Bed Flow Distribution Hydraulic Analysis, San Francisco, CA
Dr. Lewandowski was the Project Manager for a computational fluid dynamics (CFD) analysis of the filter gullets at the Harry Tracy Water Treatment Plant in San Francisco. Non-uniform distribution of flow from the gullet between filter beds was the suspected cause of observed gravel movement in the filter beds. Baffles were proposed to provide more uniform flow distribution. Dr. Lewandowski reviewed normal filter operations and three types of backwash conditions, and identified hydraulic conditions for each case. Two types of baffles, a cross-flow baffle and a bracket baffle, were analyzed. CFD results indicated the installation of the baffle would greatly improve the uniformity of flows from the gullet.
Fish Ladder and Water Plant Intake Predesign, San Jose, CA
Dr. Lewandowski was involved in the pre-design of a fish ladder on a dam at Saratoga Creek for the San Jose Water Company. The ladder pool sizes were obtained from consultations with DFG staff, and the spillway configuration was set to allow the fish to enter the ladder from a safe pool. Since the intake for a water treatment plant was located along the side of the ladder path, fish screens were necessary to allow safe passage of fish during periods of treatment plant withdrawals.
Moorpark Water Pump Station Predesign, Simi Valley, CA
In the predesign of the Moorpark Pump Station for the Calleguas Municipal Water District in Simi Valley, CA, Dr. Lewandowski developed the system head curves and pump curves for the pump station. Operational procedures included a number of different pumping scenarios to both low and high heads, with varied flow rates, and use of a pressure reducing station to reduce pump discharge head. Variable speed drives were added to the pumping units to meet the wide range of operating heads and flow rates. He also assisted in development of the pump station layout.
Engineering Solutions for Complex Water Issues