Flood Control Archives - Page 4 of 10 - Lake Worth Drainage District

Your Stormwater Pond Questions Answered

February 14, 2023/in Flood Control, News, Residential

Whether you are a long-time resident or you’re new to the Lake Worth Drainage District (LWDD) boundary, you may have noticed the many stormwater ponds that dot the landscape. While the State of Florida boasts thousands of waterways, stormwater ponds are man-made water bodies that some may mistake for natural waterways. The following are questions frequently asked by residents about the function and maintenance of stormwater ponds in their neighborhood.

Q: What are stormwater ponds and why do we need them?
A: A stormwater pond is designed to collect and manage runoff from rainwater. When rainwater lands on rooftops, parking lots, streets, driveways and other hard surfaces, the rainfall that does not soak into the ground (stormwater runoff) flows into your neighborhood stormwater pond through grates, pipes or swales. Since 1970, stormwater ponds have been required for most new developments and are specifically designed to help prevent flooding and remove pollutants from the water. Without these ponds, stormwater would carry pollutants like litter, motor oil, gasoline, fertilizers, pesticides, pet wastes, sediments and anything else that can float, into nearby canals, streams, rivers, lakes, wetlands, estuaries or the ocean.

Q: What are the different types of stormwater ponds?

A: There are 2 common types of stormwater ponds, wet and dry.

A retention or dry pond has an orifice level at the bottom of the basin and does not have a permanent pool of water. All the water runs out between storms, and it usually remains dry when it is not raining.
Wet detention systems (ponds) are the most recognizable stormwater systems. They are designed to allow material to settle and nutrients to be absorbed. After a storm, water drains from a pond through a pipe in the discharge control structure. Part of the pond — known as the permanent pool — is always below the level of the discharge control structure. Sometimes aquatic vegetation is planted around the pond’s perimeter to help filter sediment in stormwater runoff.

Q: Who is responsible for maintenance of the stormwater ponds in my neighborhood?
A: In our area, the responsibility for permitting the design and construction of most stormwater systems rests with the South Florida Water Management District (SFWMD). After developers complete construction of permitted systems in residential areas, the permit and the legal responsibility for maintaining these systems are typically passed on to a homeowners or condominium owners association. It is then that the upkeep and maintenance of the system becomes the responsibility of the association. The association is responsible for labor and expenses for keeping the system functional and operating as it was designed. Just like other infrastructure within the community, this responsibility is shared by every property owner in the neighborhood, even if they do not live adjacent to a stormwater pond, as everyone’s stormwater flows into the system.

Q: How often should detention ponds receive maintenance?

A: There are several retention pond maintenance tasks to stay on top of. The following is a list of the most important routine measures you should take to prevent more significant problems and keep your pond in good working condition.

Inspections: Stormwater pond inspections including pipe interconnections between ponds should be performed as part of an overall maintenance program. Depending on the size of the property, they should be inspected quarterly and within 24 hours of a major storm event. Look for and repair items like obstructions in the discharge control structures, trash accumulation, erosion, and sedimentation.
Vegetation management: Monthly mowing helps prevent erosion and maintains pleasing aesthetics around the stormwater pond. Property owners should minimize fertilizer and pesticide use to avoid downstream pollution.
Sediment removal: Check the amount of accumulated sediment from the bottom of the discharge control structure to ensure there is a free flow of water. Also, accumulated sediment should be removed from the pond if it has decreased the pond’s design depth by approximately more than 25%.
Structural repair and replacement: Eventually, the structural components like pipes, control structures, banks and side slopes of a stormwater pond will need to be repaired or replaced. A stormwater professional service provider can help you determine when this is necessary. Many providers can be found through an online search or phone directory.

Q: Is it ok to use stormwater ponds for recreational purposes such as swimming, kayaking or stand-up paddle boarding?
A: Recreational use of stormwater ponds may be hazardous and is not recommended. Stormwater ponds are designed to capture and retain stormwater runoff, which may contain many different types of pollution including heavy metals, pesticides, herbicides and pathogens. Additionally, the vegetation around a stormwater pond may hide dangerous wildlife like rodents, snakes and alligators. Young children, elderly individuals and pets should never be left unattended near a pond for fear of drowning or interaction with dangerous wildlife.

Q: Is it legal to fish stormwater ponds in Florida?

A: It is legally acceptable to fish in these bodies of water under the right conditions. The fisherman must have a freshwater fishing license granted by the Florida Fish and Wildlife Conservation Commission at myfwc.com and you cannot be trespassing on private property.

Q: What can property owners do to help prevent pollution in stormwater ponds?
A: Do not dump excess oils and other chemicals from your home, or yard waste like grass clippings, into stormwater ponds of associated drains. Be mindful of applying fertilizers and pesticides near ponds as rain and irrigation may wash these contaminants into adjacent water bodies. Also, be sure to clean up pet waste so nutrients and bacteria do not wash into these water bodies.

Q: Where can I find more information about stormwater ponds in my neighborhood?

A: Contact the Lake Worth Drainage District at 561-498-5363 or visit our website at www.lwdd.net for more information, printable resources and videos on the topic. To obtain a copy of your stormwater pond’s design and drainage system contact the South Florida Water Management District at 561-686-8800 or visit their online permit search at www.sfwmd.gov/epermitting.

Be Proactive With Drainage

January 17, 2023/in Flood Control, News, Residential

Come rain or shine, the Lake Worth Drainage District (LWDD) oversees the operation and maintenance of approximately 500 miles of canals. Throughout the year LWDD operates 20 major water control structures in order to release or hold back water depending on conditions. However, effective flood control takes more than just LWDD. Property owners also have a role to play in the overall flood control system.

In South Florida, flood control is a shared responsibility and is achieved through an interconnected, three-tiered drainage system. This three-tiered system is made up of tertiary or neighborhood drainage systems operated by property owners or residential associations. Secondary drainage systems are operated by LWDD, county or municipalities, and the primary system operated by regional water management entities like the South Florida Water Management District (SFWMD).

The role of property owners and residential associations is like LWDD in that they manage stormwater within their property boundary. They achieve this with the use of swales and stormwater ponds. The swales and ponds provide both water quality and flood control functions. Property owners and residential associations must maintain their drainage infrastructure to ensure that swales, catch basins, underground pipes and discharge control structures are working as designed.

South Florida’s dry season runs from approximately October to May. This time of the year is ideal to conduct inspections of drainage infrastructure and make any necessary repairs. Additionally, January and April are when many residential boards hold elections and may change property management companies. LWDD requires that these changes be provided to us as soon as possible. This will ensure the correct individuals are receiving important weather alerts and flood control instructions.

As leaders in your community, do not be caught off guard with drainage failures. Be proactive during this dry season to ensure that your infrastructure is ready for the coming rains. For more information and to submit your contact information, visit www.lwdd.net/property-managers-hoa.

What Is A Flash Flood? A Civil Engineer Explains

December 15, 2022/in Flood Control, News

The Conversation, August 2, 2022

Janey Camp, Research Professor of Civil and Environmental Engineering, Vanderbilt University

Flash flooding is a specific type of flooding that occurs in a short time frame after a precipitation event – generally less than six hours. It often is caused by heavy or excessive rainfall and happens in areas near rivers or lakes, but it also can happen in places with no water bodies nearby.

Flash floods happen in rural and urban areas, as in late July 2022 in St. Louis and eastern Kentucky. When more rainfall lands in an area than the ground can absorb, or it falls in areas with a lot of impervious surfaces like concrete and asphalt that prevent the ground from absorbing the precipitation, the water has few places to go and can rise very quickly.

If an area has had recent rainfall, the soil may be saturated to capacity and unable to absorb any more water. Flooding can also occur after a drought, when soil is too dry and hardened to absorb the precipitation. Flash floods are common in desert landscapes after heavy rainfalls and in areas with shallow soil depths above solid bedrock that limits the soil’s ability to absorb rain.

Since water runs downhill, rainfall will seek the lowest point in a potential pathway. In urban areas, that’s often streets, parking lots and basements in low-lying zones. In rural areas with steep terrain, such as Appalachia, flash flooding can turn creeks and rivers into raging torrents.

Flash floods often catch people by surprise, even though weather forecasters and emergency personnel try to warn and prepare communities. These events can wash away cars and even move buildings off their foundations.

The best way to stay safe in a flash flood is to be aware of the danger and be ready to respond. Low-lying areas are at risk of flooding, whether it happens slowly or quickly and whether it’s an urban or rural setting.

It’s critical to know where to get up-to-date weather information for your area. And if you’re outdoors and encounter flooded spots, such as water-covered roadways, it is always safer to wait for the water to recede or turn back and find a safer route. Don’t attempt to cross it. Flood waters can be much faster and stronger than they appear – and therefore more dangerous.

Engineers design stormwater control systems to limit the damage that rainfall can do. Culverts transfer water and help control where it flows, often directing it underneath roads and railways so that people and goods can continue to move safely. Stormwater containment ponds and detention basins hold water for release at a later time after flooding has ceased.

Many cities also are using green infrastructure systems, such as rain gardens, green roofs and permeable pavement, to reduce flash flooding. Restoring wetlands along rivers and streams helps mitigate flooding as well.

Often the design standards and rules that we use to engineer these features are based on historic rainfall data for the location where we’re working. Engineers use that information to calculate how large a culvert, pond or other structure might need to be. We always build in some excess capacity to handle unusually large floods.

Now, however, many parts of the U.S. are experiencing more intense storm events that drop significant amounts of rainfall on an area in a very short time period. The recent St. Louis and Kentucky floods were both on a scale that statistically would be expected to occur in those areas once in 1,000 years.

With climate change, we expect this trend to continue, which means that planners and engineers will need to reconsider how to design and manage infrastructure in the future. But it’s hard to predict how frequent or intense future storm events will be at a given location. And while it’s extremely likely that there will be more intense storm events based upon climate projections, designing and building for the worst-case situation is not cost effective when there are other competing demands for funding.

Right now, engineers, hydrologists and others are working to understand how best to plan for the future, including modeling flood events and development trends, so that we can help communities make themselves more resilient. That will require more, updated data and design standards that better adapt to anticipated future conditions.

Fallen tree and fence on canal right of way

Flood Control Resiliency

October 18, 2022/in Flood Control, News, Residential

Hurricane Ian made landfall as a category 4 storm on September 28, 2022, on the west coast of Florida. This powerful storm brought with it winds of 140 mph and torrential rain. It reminds all of us at the Lake Worth Drainage District (LWDD) how important it is for public safety to have a well maintained and operating drainage system.

Effective drainage includes the free flow of water in the canal channel and unrestricted rights-of-way for regular maintenance activities as well as emergency response. Obstruction of drainage whether over the ground or within the canal channel can have devastating effects. During severe storms trees and large shrubs can topple over causing blockages in storm drains, swale areas or flood control structures. Blockages significantly increase the risk of flooding of homes, businesses and may lead to potential life-threatening events. Additionally, encroachments on the rights-of-way can severely hinder LWDD’s use of heavy equipment needed to keep residents safe during and after severe storms.

In response to the increased frequency and intensity of our hurricanes, tropical depressions, and thunderstorms, LWDD addressed flood resiliency and established the Canal Rehabilitation Program. Phase 1 of the program addresses removal of vegetative encroachments within the right-of-way and some structural encroachments that are limiting access to the canal. Phase 1 which was established in 2018 is expected to be completed in 2023.

Phase 2 of the Canal Rehabilitation program will continue to enhance LWDD’s flood control resiliency by addressing unauthorized structural encroachments, such as fences, sheds and patios, located within the canal rights-of-way which restricts maintenance access. These encroachments will be identified and prioritized for removal. Removal of the encroachments is required and is at the expense of the property owner. Dredging and reshaping of some canal channels may be performed during Phase 2 for increased function and operation of the system.

LWDD residents, both adjacent to canals and miles inland, will benefit from enhanced flood control as well as reduced cost in post-storm clean-up. Another benefit to vegetation and encroachment removal is the faster return of residential power following a storm event as an unencumbered right-of-way will facilitate utility restoration efforts.

Hurricane Ian may have passed by Palm Beach County, but it is only time until the next storm takes aim at our coast. LWDD is committed to providing the best possible flood control for our residents today and in the future.