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Posted 7/1/2013

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By Nancy J. Sticht


Tampa Regulatory Office’s newest environmental engineer Caitlin Hoch has already added a pretty impressive credential to her resume. The recent University of South Florida graduate and her student design team, EMC Magnitude Design, Inc. took first place in a recent competition sponsored by the Florida Water Environment Association, beating 10 other teams from seven state universities. They will advance to represent the state in the national competition at the Water Environment Federation Technical Exhibition and Conference this fall.

EMC Magnitude Design, Inc. was contracted by its client, the city of St. Petersburg, to investigate algae blooms within Booker Creek, a high quality water resource that drains into Tampa Bay, and to suggest stormwater improvements to alleviate nitrogen over-enrichment.

“Excess loading of nitrogen and phosphorous compounds is one of the most prevalent causes of water quality impairment in the United States, significantly impacting aquatic life and long-term ecosystem health, diversity and balance,” said Hoch. “It results in harmful algal blooms, reduced spawning grounds and nursery habitats, fish kills and oxygen-starved hypoxic or ‘dead’ zones.”

Algal blooms can block sunlight needed for submerged grasses and other organisms to grow. They can increase turbidity, impairing the ability of aquatic life to find food, and can damage or clog the gills of fish and invertebrates.

Excess algal blooms also result in a range of economic losses, including lost revenue from impacts to commercial fisheries, recreational fishing and boating trips and tourism. Drinking water cost increase and waterfront property value decrease. 

According to research conducted by EMC Magnitude Design, Inc., Florida’s marine recreational fisheries economic value is higher than any other state in the country, contributing more than $5 billion of Florida’s economy in 2006. In 2008-09, more than one million individuals bought a marine recreational fishing license, generating approximately $29 million in revenue. Similarly, Florida has one of the nation’s top producing commercial fisheries.

Booker Creek is located in Pinellas County, the most densely populated county in Florida, where about 90 percent of the area has been converted from its natural state to urban land uses. The suspected main source of nutrient loading into Booker Creek is residential and commercial fertilizer applications. The primary objective for the design team was to address these concerns by reducing human-caused nutrient levels and coupling it with a design to treat stormwater runoff.

After analyzing data, land uses and several other sources, the team determined that the headwaters of Booker Creek, specifically Woodlawn Lake, were the primary contributor to the impairments and focused their efforts on reducing the nutrients draining from the lake into Booker Creek.  

Their proposed design included building a new component to add to an existing weir to limit the amount of water draining from the lake, re-grading the banks of the lake and widening the littoral shelf. Holding water in the lake for a longer period allows time to treat the water and remove a percentage of the pollutants by allowing them to settle and then be absorbed by vegetation, resulting in cleaner water flowing into the creek. An overflow weir will allow water to drain from the lake when there are heavy rains, so the surrounding neighborhood will not flood.

Another element of the proposed design is the placement of Floating Treatment Wetlands (FTWs), buoyant mats through which plants grow into the water below. The plant roots stay suspended in the water column, providing a large surface area for direct nutrient uptake from the water column and treating the water as it passes through the roots. Finally, the team recommended non-structural elements such as public education and routine maintenance, including mowing the lawn, removing dead vegetation, planting new vegetation and cleaning up trash. 

“The main goal of the entire project is to gain some ‘real world’ experience, so we acted as an actual engineering firm, not just a student team,” said Hoch. “EMC Magnitude Design, Inc. stands for Erin, Miki and Caitlin, the three original members of the team. Two other members joined us later.”

Hoch’s role on the team was to analyze historic and current water quality data within Booker Creek. She analyzed data that was uploaded to an online data warehouse managed and maintained by the U.S. Environmental Protection Agency. The team also had water quality samples taken within the headwaters of Booker Creek at Woodlawn Lake and Booker Lake to be tested for levels of total nitrogen, dissolved oxygen, and chlorophyll a in support of their study.
 
“We were able to successfully identify a significant problem within the Booker Creek watershed and develop an achievable design that has beneficial results. Our client was so pleased with our design that he is working to have it implemented,” Hoch reported.

Hoch, who has served in Jacksonville District as a student aide since 2008, earned her bachelor’s degree in civil and environmental engineering and was recently promoted to her new full-time position.  She and her team will present their project design at the national competition in Chicago in October.



algae blooms Booker Creek Caitlin Hoch corps EMC Magnitude Design Floating Treatment Wetlands Florida Florida Water Environment Association Inc. Jacksonville District Pinellas County regulatory division St. Petersburg Tampa U.S. Army Corps of Engineers University of South Florida USACE