Gantzer Water provides expertise to major engineering firms in the review and design of aeration and oxygenation systems to enhance or improve water quality through in-lake management strategies. Gantzer Water focuses on a comprehensive oxygen analysis to establish baseline oxygen demand for initial system sizing and strategy focus.
Eutrophic water bodies that thermally stratify in the summer often experience anoxia in bottom waters, which in turn results in the release of soluble compounds to the water column, e.g. phosphorus, iron, and manganese. The added nutrients exacerbate eutrophication while adding additional treatment costs for water distribution. Gantzer Water works closely with each firm to address their client’s needs and goals to provide the most robust long-term management strategy within budget constraints.
C.W. Bill Young Reservoir
The C.W. Bill Young Reservoir, operated by Tampa Bay Water (TBW) is a manmade side-stream water supply reservoir constructed and first filled in 2005 to provide water-supply storage to the Tampa Bay Region. Diffused air destratification (DA/D) and hypolimnetic aeration using full-lift aerators (HA), installed in 2005, were evaluated for replacement to coincide with current reservoir construction. The overall goal of the aeration system as defined by TBW is to “reduce existing dissolved iron and manganese, minimize the concentration of these metals in the raw water intake (control tower), promote oxidation of organic matter, decrease conditions conducive to blue-green algal biomass, and reduce the anaerobic zone in the lake.”
The evaluation phase of this project was completed fall of 2012 and is currently moving toward the design phase. Gantzer Water is currently working with Robert Kortmann of Ecosystem Consulting and Mark Mobley of Mobley Engineering under the management of Gannet Flemming to replace the HA and DA/D systems respectively.
Ni River Reservoir
Ni River Reservoir is a manmade water-supply reservoir that supplies drinking water to Spotsylvania County. The reservoir experiences seasonal anoxia in bottom waters and corresponding elevated Mn levels. Currently, Gantzer Water is working with Hazen and Sawyer to perform a feasibility study to evaluate oxygen demand and development of a hybrid management strategy using side-stream super saturation (SSS) and aeration line-diffuser surface mixing.
Falling Creek Reservoir
Falling Creek Reservoir is a surface water source in Bedford County east of Vinton, VA that is operated and maintained by the Western Virginia Water Authority (WVWA). The reservoir has experienced repeated algal blooms that are exacerbated by anoxic conditions on the bottom and intermittent mixing caused by occasional adverse weather. The WVWA observed some success with algae control with the use of copper sulfate; however, they were interested in alternatives to chemical algae control and developing an overall reservoir management strategy.
Gantzer Water and Mobley Engineering designed and installed a hybrid water quality management system using side-stream super saturation (SSS) to inject oxygenated water to the bottom of the reservoir and line-diffuser destratficiation to actively mix the surface waters. The system was installed in fall 2012 and will be operated at full capacity starting in spring 2013. The design and hybrid management strategy was presented at 2012 NALMS 32nd International Symposium.
Spring Hollow Reservoir
Spring Hollow Reservoir is a deep (max depth > 200ft) pump-storage water-supply reservoir located in Roanoke County, VA that is operated and maintained by the Western Virginia Water Authority (WVWA). Following the construction and initial filling in 1996, an aeration line diffuser was installed by the Tennessee Valley Authority (TVA) as a water quality management strategy. Paul Gantzer studied the aeration system in detail as a graduate student at Virginia Tech and worked with the WVWA and Mobley Engineering to redesign the line diffuser to upgrade for pure oxygen. The resulting work paved the way for extensive research related to hypolimnetic aeration and oxygenation design and operation.
Carvins Cove Reservoir
Carvins Cove Reservoir is a moderately deep (max depth 70ft) water-supply reservoir located just north of the City of Roanoke, VA that is also operated and maintained by the Western Virginia Water Authority (WVWA). Carvins Cove historically experienced anoxia in the bottom waters and subsequently elevated Mn levels. Gantzer applied his knowledge obtained at Spring Hollow to design, oversee installation, and operate a Mobley hypolimnetic oxygenation system. Carvins Cove provided a second full scale oxygenation system to operate and subsequently research. Several years of operation and research resulted in two publications in Water Research, (1) Controlling soluble iron and manganese in a water-supply reservoir using hypolimnetic oxygenation (doi:10.1016/j.watres.2008.12.019) and (2) Effect of hypolimnetic oxygenation on oxygen depletion rates in two water-supply reservoirs (doi:10.1016/j.watres.2008.12.053)
Occoquan Reservoir
Occoquan Reservoir is a riverine reservoir with a very short residence time, ~19 days. Occoquan reservoir has historically struggled with algae, anoxia in the bottom waters, and elevated Mn levels in the water column. Gantzer Water worked with Malcolm Pirnie | The Water Division of ARCADIS to evaluate the historical aeration performance, and design a replacement management strategy to address elevated Mn in bottom waters during summer stratification. The resulting project was approved for a Mobley line-diffuser hypolimnetic oxygenation system, which was installed and operated in 2012.
Vadnais Lake and Pleasant Lake
Vadnais and Pleasant lakes are water-supply sources that are maintained by St. Paul Regional Water Service (SPRWS). Both lakes had aging full-lift aeration towers to combat summer anoxia following the onset of thermal stratification. Despite the aeration tower operation, Mn levels were observed to be problematic.
Gantzer Water worked with CH2MHILL addressing the primary goal to evaluate historical aeration performance, and design a replacement management strategy to address elevated Mn in bottom waters during summer stratification. Resulting designs were line diffuser hypolimnetic oxygenation systems, which Vadnais Lake was installed and successfully operated in 2012 and Pleasant Lake will move to construction in the near future.
