Pinellas Park Water Management

30 years of goals and accomplishments

In the 1950s, paper carriers in Pinellas Park, FL, had a unique way of dealing with the city’s severe flooding problems. On rainy days, the carriers wrapped their newspapers in waxed paper bags. This kept the papers dry and enabled them to float, ideally long enough for residents to retrieve them. Eventually, though, the waxed paper became saturated and the papers sank in the standing water.

The Pinellas Park area has experienced relentless flooding for decades. The low-lying area has the Gulf of Mexico a short distance to the west and Tampa Bay to the east. Pinellas County, in which Pinellas Park is located, averages 52 inches of rainfall each year, with the majority of rain occurring in a four-month period. During wet weather, the groundwater table rises nearly to the surface, causing the area to flood during even the smallest rain events.

Harry Marlow, PLS, a retired land surveyor who has lived in Pinellas Park since 1956, recalls seeing children paddle up his street in canoes after thunderstorms. “My office was about 1 mile from my house, and I can remember it taking me 45 minutes to get home because of the water,” he says.

Weary of the flooding, in 1975 the citizens of the Pinellas Park area asked the Florida State Legislature for help. The legislature recommended creating a special district dedicated to stormwater management. That same year voters agreed, by a 2.5:1 ratio, to tax themselves up to 3 mills ($3 for every $1,000 of assessed property value) to create a State of Florida special water management district called the Pinellas Park Water Management District (PPWMD).

The PPWMD had one primary goal: to alleviate flooding by retaining the runoff from 25-year/24-hour recurring storm events within channel banks and 100-year/24-hour storm events out of houses. Today, after 30 years in operation, the district is only a few projects away from meeting that goal.

The design criteria established at the district’s inception were fine-tuned in 1992 and currently dictate the basis of drainage improvement designs. They are as follows:

• Contain the 25-year flood event within the channel banks with 1 foot of freeboard where possible.
• Minimize head losses at culverts and bridge crossings to maintain clearance above the 25-year flood event.
• Provide adequate capacity within the primary drainage system to be consistent with a 10-year storm event design capacity in the secondary drainage system.
• Limit flooding during a 100-year flood event to streets and yards if possible.

Before: Channel 3 looking east from 35th Street North

After: Channel 3 looking east from 35th Street North, concrete lined

District Plans, Builds, Manages, and Maintains Infrastructure
The PPWMD is responsible for managing the primary stormwater drainage system in its approximately 15-square-mile jurisdictional area, which encompasses the city of Pinellas Park and unincorporated Pinellas County. The secondary systems, including street drainage, curb and gutter inlets, and associated conveyance systems, are maintained by the city and county.

The district is governed by a board of directors appointed by the City of Pinellas Park City Council and the Pinellas County Board of County Commissioners. The work of the PPWMD is carried out by the executive director, a staff of administrative and maintenance professionals, and consultants.

Irrigation Ditches Converted to Drainage Basins
The PPWMD area began as an agricultural community recognized for its flower farms. Local farmers also raised dairy cattle and harvested sugar cane and vegetables. Around 1915, many ditches, including five major ditches that are still in use today, were built to irrigate farmland.

The area was hit hard by the Great Depression of the 1930s. The economy floundered, and many of the 2,000 residents left to pursue work elsewhere. Development along south-central Florida’s roads, combined with the growth of nearby St. Petersburg, helped bring the area and the city of Pinellas Park, in particular, back to life. By 1960, more than 11,000 people called the area home, and as of April 1, 2006, the population was estimated at 48,835. The city is 16.09 square miles, based on annexation data collected from 1950 through June 2003. Because of voluntary annexations, the city’s physical size is continually growing.

From the beginning, the PPWMD recognized that the five ditches would serve as the backbone of its stormwater management program. As capital improvements progressed, the ditches, configured as a system of channels, began functioning as drainage basins. Based on this, the PPWMD was divided into five primary service areas, described as follows:

• The Channel 1 Basin flows westerly to its outfall at the Cross Bayou Canal. The conveyance system is composed of concrete-paved and concrete-filled fabric-lined channels, grass-lined reinforced earthen channels, bridges, culverts, unimproved channels, and pipe systems. The channels total approximately 9.3 miles in length, with bottom widths ranging from 2 to 26 feet.
• The Channel 2 system comprises a main channel and four tributary channels that provide drainage for approximately 2,270 acres. Channel 2 serves as the major outfall for a city-maintained storm sewer, as do all the other channels. The general flow is easterly, and the 6 miles of channels, bridges, culverts, and pipe sections discharge to Sawgrass Lake.
• Drainage in the southeastern boundary of the PPWMD occurs within the Channel 3 Basin, which also discharges to Sawgrass Lake. The channels in Basin 3 total 2.8 miles in length and include piped sections, bridges, and concrete-paved and unimproved channels.
• Located in the southwestern portion of the PPWMD is the Channel 4 Basin. It includes a main channel, three minor tributaries, and a lake. The basin drains approximately 1,857 acres and flows southwesterly to its confluence with Joe’s Creek. The channels measure 4.7 miles in length.
• The Channel 5 Basin is a 560-acre drainage area in the central portion of the district’s jurisdiction. The system, which flows southwesterly to its outfall at Joe’s Creek, consists of unimproved channels, concrete-paved channels, articulating block–paved channels, bridges, culverts, a piped storm sewer system, and other piped sections measuring approximately 1.4 miles in length.  

First Projects Help Open Water Flow
The first few years of the PPWMD’s existence were spent developing master plans for each drainage basin. These were updated in the 1990s and are still in use today. Directing the efforts was the district’s first executive director, Morton S. Lipschultz, P.E. Lipschultz was a Pinellas Park resident who had worked with the city as a consulting engineer in private practice. He was instrumental in the district’s establishment and served as executive director until 1995. Through his knowledge of civil engineering, Lipschultz represented the technical side of the PPWMD’s creation and justified how the area’s flooding problems could be addressed. The political components of the district’s endeavors were spearheaded by some long-established residents and community champions, including Loyd Tingler and Joe Wornicki.

The Loyd Tingler Nature Park features recreational amenities while accommodating water storage and addressing water-quality issues.

The recirculating drawdown pump station at the park

The PPWMD’s first engineering consultant was Greiner Engineering Sciences Inc. (now URS Corp.). In 1979 construction began on the district’s first project—a concrete-lined channel in the Channel 1 Basin. On May 9, 1979, a slow-moving, low-pressure storm dumped between 10 and 16 inches of rain across Pinellas County and caused severe flooding in Pinellas Park. Cars were submerged to their rooftops. Hundreds of homes and businesses were flooded. One resident recalls walking home in water almost to his shoulders. Obviously, the work of the PPWMD had not started a moment too soon.

The early projects focused on the downstream ends of the five basins. Concrete-lined channels and concrete-filled fabric-lined sediment traps and embankment erosion protection were installed to prevent erosion, decrease hydraulic friction, and reduce maintenance. Where possible, the projects typically widened and deepened the channels to maximize conveyance to the outfalls and to increase storage. This helped move the stormwater more effectively from the drainage basins and residential neighborhoods. Each year, the PPWMD completed three or four more projects, gradually fulfilling its master plan recommendations and its ultimate goal of alleviating flooding in the Pinellas Park area.

In 1990, CDM became the district’s general engineering consultant to oversee design and construction of multiple drainage improvement projects. In 2003, the engineering firms of McKim & Creed, TBE Group, and Advanced Engineering & Design were also selected to assist the district. Together, these firms are helping the PPWMD complete its final projects.

Paradise in Concrete
Originally, all concrete-lined channels included concrete bottoms. However, with the ever-increasing focus to refine water-quality standards, the Southwest Florida Water Management District (SWFWMD) expressed concern that the concrete-lined bottoms would negatively impact existing wildlife habitats and water quality. To address this, and to provide the stormwater with more contact with natural ground, an alternate design was proposed. The PPWMD and its engineers redesigned most channels to incorporate a natural bottom with concrete sides. The earth bottom created an attractive environment for grasses and other vegetation, while the reinforced concrete sideslopes stabilized the embankments, prevented erosion, and virtually eliminated slope maintenance.

To support the mostly 1.5-foot-horizontal to 1.0-foot-vertical sideslopes of the reinforced concrete-lined channels, engineers developed a reinforced concrete strut design connected to the sideslope’s reinforced concrete footers.

Whether the channels were constructed with concrete bottoms or open/natural bottoms, habitats and ecosystems prevail. The concrete-lined bottoms capture sediment, which allows wetland plants to grow and encourages wildlife to inhabit the space in search of food. These drainage channels are home to fish and crabs in the downstream tidal areas. Egrets, herons, ducks, anhinga, and osprey populate areas surrounding the channels because of the consistent food source. Occasionally, an alligator, water moccasin, copperhead, or otter is spotted.

Volunteers Help Build Park Amenities
In 1992, the PPWMD completed one of its most ambitious projects: the Loyd Tingler Nature Park. Originally, the project was defined as a water-quality and flood control facility, but through the actions of Lipschultz and the community, it evolved into a city park that fulfills its original purpose and provides a recreational amenity.

The sediment pond is shown in the foreground of this photograph, with the littoral area in the background and to the left.

The park was originally the vision of the Florida Department of Environmental Regulation (DER) and the PPWMD Board of Directors. Through hydrologic and hydraulic modeling, it was determined that stormwater storage would be required to reduce flooding in the Channel 1 Basin. The Florida DER proposed that an offline facility directly connected to Channel 1 be designed to provide storage and to reduce flooding. In addition, the facility would serve as a water-quality enhancement area to mitigate the perceived loss of habitat and runoff treatment because of the recommended concrete lining of Channel 1. Through stormwater analysis, the PPWMD’s consultant determined that the concentration of nutrients and metals was greater in tributary Channel 1C than in the main Channel 1. Therefore, the design diverted Channel 1C instead of the main channel. This allowed normal flow to enter the facility via a diversion weir. The weir was designed to divert flow up to the 25-year/24-hour recurring storm event through one 54-inch circular reinforced concrete pipe.

The facility was designed to be an offline retention and sedimentation pond. Flow—under normal conditions and up to the 25-year event—conveys sediment that settles in a pond. The flow then continues to a shallow, littoral area containing native Florida wetland and upland plants and trees selected for maximum nutrient uptake and then to an outfall structure with a bleed-down orifice to Channel 1.

The facility also features a pump station containing two 650-gallon-per-minute pumps. The valving configuration at the station allows the PPWMD to lower the pond volume and discharge to the adjacent concrete Channel 1 if a major storm event is approaching. The dual-use pump station normally operates with a timer to recirculate the pond water, thereby preventing the lake water from becoming stagnant.

While the original purpose of the facility was to serve as a flood control and water-quality improvement area, it didn’t take long for the PPWMD and the community to realize that the site could provide additional benefits not only to the environment but to the community as well. The result is a 6.4-acre park and nature area that features a lake with cypress trees, pine, Florida native wetland plants, a gazebo, a boardwalk, a picnic area, and an equestrian trail.

Lake Boisvert is an offline water storage facility that has reduced flooding in Pinellas Park.

An aerial view of Loyd Tingler Nature Park

It was brought to fruition through the help of volunteers from the local community. Members of the Pinellas Park Kiwanis Club helped lead the volunteer effort. The local chapter of the Florida Engineering Society donated the engineering design. A contractor developed the construction plan free of charge.

The park was named for the late Loyd Tingler, who served on the PPWMD’s Board of Directors from 1975 though 1987 and was instrumental in making the PPWMD a reality. In 2000, ownership of the Loyd Tingler Nature Park was transferred from the PPWMD to the City of Pinellas Park.

Innovative Lake Design Offers Offline Stormwater Storage
While many areas in Pinellas Park were infamous for flooding, the Channel 3 Basin was especially notorious for overflowing into nearby neighborhoods and, specifically, the Fortuna Park subdivision. Analysis, modeling, and other assessments helped engineers determine that water storage for this drainage basin was necessary in the upstream portion of the watershed. Unfortunately, the surrounding area was almost completely developed and offered very little land available for offline storage.

The PPWMD investigated several areas, including a public soccer field, a small forested area, and a piece of property that was home to the district’s new headquarters. The PPWMD had recently relocated its offices to this parcel, and hydrologic and hydraulic analyses indicated that the district’s property was the optimal location for the much-needed water storage facility. Ever faithful to its mission of alleviating flooding in Pinellas Park, the district made the land available for the design and construction of Lake Boisvert.

Named for former board member Andrew Boisvert, the lake was designed as an offline stormwater storage facility that would help store a significant volume. Because of Lake Boisvert and street drainage improvements made concurrently by the city, the flood stages were lowered in the surrounding area and, in particular, Fortuna Park. This project became an essential element in the overall Channel 3 master plan.

As runoff enters Channel 3, the water rises in the main channel and then drains into Lake Boisvert before overflowing the channel banks. This additional storage, as well as the wider, deeper concrete lining of Channel 3, has measurably reduced street flooding to the surrounding residences.

The additional storage provided by the offline Lake Boisvert was created not only by the construction of the lake itself but also by the way in which its volume and function are maximized, even in a constrained size and location. To create more available storage volume, the lake is artificially kept low by draining it to a depth below the surrounding normal water table. This is done by installing a discharge pipe with a backflow prevention flapper valve that keeps the lake at this low elevation and continuously drains the lake to the level of Channel 3. A concrete weir separates the lake from the tributary connected to the main channel, Channel 3. The discharge pipe penetrates the concrete weir.

Permitting for this project proved difficult but not impossible. The permitting authority, the SWFWMD, was concerned that by artificially lowering the normal water table, surrounding structures, primarily light industrial in nature, could be affected. To acquire the permit, groundwater modeling was performed, which indicated no impact to these structures. Channel 3 was concrete-lined from Fortuna Park to the entrance to Sawgrass Lake. Two inline widened areas upstream of US 19 were installed on land purchased from a local electric utility, Florida Power Corp. (Progress Energy).

A Project Put to the Ultimate Test
On February 3, 2006, the skies opened up over west-central Florida, dumping 9 inches of rain in three hours and a total of 11.35 inches of rain in 24 hours. Roadways became lakes. Roofs collapsed. People were stranded as water flowed into their cars. Everything flooded … almost. The final upstream project in the PPWMD’s Channel 1 Basin—a concrete-lined drainage channel and culvert system—worked in conjunction with other downstream improvements to keep areas of the city functional and drivable during the record-setting deluge.

The $1.6 million system, designed by McKim & Creed, replaced an open vegetated ditch with 1,100 feet of concrete lining featuring an open, natural bottom. A roadside drainage ditch plagued by erosion was converted to 650 feet of box culvert below a neat grass catchment area.

Put to its first major test, the system performed better than expected. Water rushed through the culvert instead of the streets. Two intersections close to the project held 3 to 4 inches of standing water for a few hours, rather than days. The roads were easily passable, and no houses in the area were flooded.

Maintaining the Infrastructure
The PPWMD is responsible not only for building the stormwater management infrastructure but also for maintaining it. To accomplish this, the district employs 12 people, including an executive director, administrative and support professionals, and maintenance specialists.

Before: Channel 3 looking east toward 35th Street North

After: Channel 3 looking east toward 35th Street North

In some areas, the channels traverse residents’ yards, so the channels must be kept clean, functional, and kempt. The channels are mowed twice each year during the growing season. Blockages, which can include everything from storm debris to couches and chairs, are removed as needed to keep the stormwater flowing. Sediment traps in the channel bottoms are routinely cleaned to prevent obstruction. Most of the channels contain weep holes, which are cleaned regularly to prevent groundwater pressure from building up behind the concrete walls.

Because some of the channels are as wide as 26 feet, a variety of equipment is required to keep them maintained. The district has two Spyder excavators that can excavate, trim, and mow, with the ability to infiltrate places humans cannot. Also included in the arsenal of maintenance equipment are a variety of mowers, a front-end loader, four dump trucks, sprayer equipment, emergency pumps, and a boat.

Knowing the Past Helps Determine the Future
In the 1990s, the district installed rain gauges and level recorders so it could record rainfall, maintenance activities, and the water level in each of the channel basins. Monthly reports are produced, and the information is incorporated into the PPWMD’s geographic information system. An annual report summarizes the previous year’s rainfall and maintenance activities and outlines projects to be completed in the following year.

Since the district was established, flooding in the Pinellas Park area has decreased sufficiently for the district to apply for a Letter of Map Revision to the Federal Emergency Management Agency. If accepted and revised, updated Federal Insurance Rate Maps (FIRMs) will reduce the 100-year flood zones as defined by the FIRMs. Homeowners’ flood insurance requirements will be eliminated because of the proven and observed reduction in flooding.

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The city has grown and benefited significantly as developers, now confident that new communities will not be plagued by flooding, have built new neighborhoods. “The district has done a tremendous amount of good,” says Marlow. “People were afraid that if they built here, their homes would flood. Now people are coming here in droves. It took a lot of hard work on the part of people in the 1970s to get this district set up and approved.”         

The PPWMD anticipates completing its originally identified projects in 2009. At that time its goal—to alleviate flooding in the Pinellas Park area by keeping 25-year storms within channel banks and 100-year storm events out of houses—will be accomplished. As the PPWMD works to complete its mission, it has found that recent additional higher-density land uses are increasing the amount of runoff, and additional projects are being evaluated to accommodate the increased flows. Maintenance repairs and rebuilding due to wear and useful structure life failure are also being identified and will be addressed in the near future.

Author's Bio: Daniel E. Glaser, P.E., is an associate with McKim & Creed and manages stormwater engineering in the firm’s Clearwater, FL, office.

Author's Bio: Richard O. Fraze, P.E., is the executive director of the Pinellas Park Water Management District and served on the Board of Directors from 1984 to 2006.