HOW TO OPERATE & MAINTAIN YOUR STORMWATER MANAGEMENT SYSTEM

Surface water management facilities, such as ponds, ditches & swales, are constructed to trap & filter out pollutants in stormwater runoff from roads, parking lots, buildings, & lawns. Discharge of untreated water to natural lakes, creeks, & rivers is harmful to natural vegetation & wildlife. This destroys one of the very things we like best about Florida - our enjoyment of the abundant clean water for recreation & aesthetic enjoyment. The purpose of this informational guide is to provide the entity/permittee responsible for the operation & maintenance of the Stormwater Management System (SWMS) with guidelines for establishing a program of routine maintenance procedures, which should minimize problems & maximize the appearance & performance of a SWMS. Typically, site developers are responsible for operation & maintenance until construction is complete, then they are required by permit condition to transfer this responsibility to a homeowners’, condominium owners’, or property owners’ association. After an association is legally established & construction of the surface water management system is completed, the association will assume responsibility. The operation & maintenance entity for shopping centers, individual stores, & offices typically is the landowner or a management company hired by the landowner.   

Your (SWMS) is designed & constructed to comply with certain environmental protection criteria. Stormwater ponds & their associated surface water management facilities are designed to capture & remove pollutants from specific volumes of stormwater runoff through processes such as percolation, filtering, &/or detention. As long as they are constructed properly & maintained in an effective state, water quality standards are presumed to be met. Stormwater management systems should be inspected on a routine basis to ensure that they are functioning properly. Inspections should be scheduled on a monthly or quarterly basis & following any major rain event. More frequent inspections may be necessary during the rainy season. Keeping detailed notes on maintenance activities will help when providing a report to the Southwest Florida Water Management District (District) at the time of your 18 or 24 month inspection. Environmental Resource Permit (ERP) or your Management & Storage of Surface Waters (MSSW) permit includes a condition that specifies how often the inspection reports are due. It would be wise to designate one individual as the person responsible for overseeing operation & maintenance activities, monitoring & reporting. This will allow that individual to become well acquainted with the SWMS. Provide this person with a copy of the permit & District-approved construction drawings should questions or issues develop.

1. All stormwater pipes, inlets, catch basins, manholes, flumes, pond inflow & outfall structures (including oil skimmers), & discharge pipes should be inspected on a regular basis (monthly or quarterly) & after major rainfalls. They should be maintained by removing built- up debris & vegetation & repairing deteriorating structures. 

2. Chemicals, oils, greases or similar wastes are NOT to be disposed of directly to the stormwater facility or through storm sewers. Treatment ponds are designed to treat normal road, parking lot, roof & yard runoff only. Some chemicals may interfere with a treatment pond’s functions or kill vegetation & wildlife. Dispose of these potentially dangerous materials properly by taking them to recycling facilities or to collection locations sponsored by many local governments. Also, do not dispose of grass clippings in a SWMS. Grass clippings pose problems by smothering desirable vegetation, clogging outfall structures &, when they decompose, may cause unsightly algae blooms that can kill fish. 

3. Accumulated pond sediments may contain heavy metals such as lead, cadmium & mercury, as well as other potentially hazardous materials. Therefore, sediments removed from storm sewers, inlets, pipes & ponds should be disposed of at an approved facility (check with your county Solid Waste Department or the Florida Department of Environmental Protection for disposal facilities approved to accept treatment pond sediment). 

4. During any repair or maintenance activity, use care to avoid causing erosion or siltation to adjacent or off-site areas. 

5. Remember, alterations (filling, enlarging, etc.) of any part of the stormwater facility is not permitted without prior approval from all applicable governing agencies. 

6. The approved Operation & Maintenance Permit & as-built drawings are available at your local District service office. Refer to those plans & permits or additional restrictions, instructions, & conditions. 

7. It is usually more cost-effective to monitor & perform routine maintenance on a SWMS, rather than let it fail & have to reconstruct the entire system. 

8. Mosquito growth can be minimized in a SWMS by the following measures: 

• Do not dump grass clippings or other organic debris into a SWMS. Decaying grass clippings & other decomposing vegetation create ideal conditions for breeding mosquitoes. 

• Clean out any obstructions that get into the system. Debris can obstruct flow & harbor mosquito eggs & larvae. 

• Remove water lettuce & water hyacinth, which nourish & shelter mosquito larvae. 

• Stock ponds with predatory "mosquito fish". Gambusia minnows, may be collected from other ponds & ditches & introduced into your SWMS. Remember, the introduction of grass carp into your SWMS will require District approval. 

Some Environmental Resource Permits & (Management & Storage of Surface Water Permits) require that the vegetation in some ditches be protected to offset wetland impacts permitted during construction or for water quality treatment. The permit or approved construction should clearly identify which ditch vegetation must be preserved. If you’re unsure, contact your local District service office. If vegetation is not required to be protected, ditches & swales should be periodically mowed & cleaned of accumulated refuse. During the mowing operations, ditches & swales should be inspected for bare spots, damage or erosion. Bare areas should be sodded or seeded to replace the grass cover. In the case of erosion, replace the missing soils & bring the area back to grade. Some ditches are designed to store runoff for short periods of time utilizingmethod serves your development, contact your District service office.

How to recognize: Drive retention ponds are designed to be dry, except for 72 hours following a rain event, or a series of rain events if they occur frequently. They are sodded or grassed, with a concrete overflow structure that typically has a metal grated top a rectangular or v-notch weir in the side with an aluminum or fiberglass skimmer around the weir.

How they work: A portion of the sites stormwater percolates through the top soil. The pollutants settle out & are trapped in the ponds bottom. Exposure to sun & oxygen helps break down the greases & oils.

Why they fail: Accumulated sediments with silts, oils, & greases eventually seal off the porous bottom sands resulting in little or no percolation through the filtering sands. Untreated water may discharge through the overflow structure if this occurs. 

1. On a monthly or quarterly basis, & following a storm event, the entity responsible for maintenance should make an inspection of the pond & its outfall structure to ensure that the system is operating properly. If standing water persist longer than 72 hours after a normal summer rain event, or if the wetland vegetation such as cattails grow in the pond, the stormwater facility maybe in need of repair. Repairs may be as simple as scarifying or raking the pond bottom, or may consist of removing the bottom sediment (approximately the top foot of soil) & replacing the soil with clean sand. For more information contact your local district service office. 

2. Mow frequently enough to prevent thatch build up. Pick up grass clippings after cutting. Limit fertilizer use around the pond, & do not fertilize grass in the pond area. 

3. Resod any areas (sides or bottom) where grass or sod has been removed or eroded. 

4. Keep the outfall structure clear of debris & vegetation. 

How to recognize: These ponds may either be dry or wet, but rely on a filtration system made of perforated pipe laid in a bed of filter media, such as sand, to remove pollutants. “Cleanouts” or vertical pipes with caps screwed on top, are connected to the buried pipes & extend up to the pond surface or bank. It is essential that the cap is always kept secured on the cleanout so that untreated water is not discharged through the cleanup. How they work: A portion of the sites stormwater percolates through the filter media into the perforated pipe & out through the control structure. Pollutants settle out or are trapped in the filter media. In addition, exposure to sun & oxygen helps break down the greases & oils. 

Why they fail: The filter bed may become clogged with accumulated sediment, oils, & greases, resulting in little or no percolation through the filtering sands. Untreated water may discharge through the overflow structure if this occurs. 

Maintenance Suggestions: In general, if approximately 36 hours after a rain event you notice that water discharges over the top of the concrete control structure, rather than through the perforated pipe, it may be a signal that the pond is not functioning properly. 

1. On a monthly or quarterly basis, & following a storm event, inspect the pond & its outfall structure to ensure that the system is operating properly. Repairs may be as simple as scarifying or raking the filter sand, forcing water through the cleanout to cleanse the perforated pipe, or as involved as replacing the filter media. Check construction plans or contact the District for more information if any questions arise. 

2. Mow frequently enough to prevent thatch build up. Pick up grass clippings after cutting. Limit fertilizer use around the pond, & do not fertilize grass in the pond area. 

3. Resod any areas where grass has been removed or eroded. Do not sod over the filter media. Place stone or gravel over the filter media for stabilization, if necessary. 

4. Keep the outfall structure clear of debris & vegetation.