Drainage improvements for Meadowglen Drive and Falkner Road: Challenges and successes
Deodat Budhu, P.E., Manager, Roads & Drainage Division, and Elizabeth White, Engineer, Orange County Public Works Department, Orlando, Florida
Prior to the State of Florida's adoption of stormwater regulations, numerous subdivisions around central Florida were built without stormwater management facilities (i.e., stormwater ponds). In Orange County in the late 1950s and early 1960s some subdivisions were built in various stages and no stormwater management facilities were part of the construction plans.
Representative areas of this problem are found along Meadowglen Drive and Falkner Road. Residents' complaints for the Meadowglen area have historically focused upon an existing ditch located behind the homes along Meadowglen Drive. County records and complaint logs indicate that residents have been concerned with backyard erosion along the ditch as well as lack of maintenance from County crews. On Falkner Road, residents' complaints have historically focused upon the potential for flooding of homes that abut the road.
Drainage improvements proposed in and around these areas are in essence two separate projects, with different improvements in response to two unique problems. Due to the proximity of the two areas, Orange County proposed to construct all the drainage improvements at the same time. Combining construction activities normally results in a cost-saving operation compared to performing the construction separately.
The majority of the Meadowglen Drive area was constructed in various stages. The area consists of various subdivisions: Plantation, Avonwood, and Plantation Estates. The existing Meadowglen Drive drainage ditch is situated between the subdivisions. The ditch originates north of Falkner Road and flows to the south and discharges into Lake Lovely. Approximately 75% of the conveyance system is an open ditch while the other 25% consists of storm pipes and culvert crossings.
Meadowglen Drive drainage ditch (before)
Existing problems in the area have been routine maintenance being extremely difficult due to the location of the ditch in relation to the property lines, power poles, fences, trees, etc., even though an existing drainage easement provides Orange County legal rights to access the ditch.
Orange County has maintained this drainage ditch using manual labor considering that using heavy equipment was impossible in order to provide proper drainage and limit the potential for flooding.
Erosion also presents a problem for several backyards, especially from high water velocity during moderate 5- to 10-year storm events.
The continuous complaints from the residents raised the possibility of enclosing the ditch with a storm collection system creating a shallow swale system with inlet tops in order to provide some level of water quality treatment. Proposed improvements would not alter the existing basin limits and therefore would not impact the receiving system (Lake Lovely) with respect to increased flow rates or pollutant loadings.
To enable the possibility of enclosing the ditch, pipes would have to cross private properties and therefore Orange County would need to obtain perpetual drainage easements from the homeowners. Easement donations from residents have been a problem in the past resulting in nothing being done to address the problem. To ensure the success of the easement donation, a neighborhood meeting with the affected homeowners was held. The advantages and disadvantages of piping the ditch were explained. Residents balanced the improved flooding and closure of the open ditch, "gaining" more backyard areas, with the net benefit of easement donation, against the short inconveniences during construction (i.e., having heavy equipment within feet of the backyard, material stockpiling, and removal of privacy fences). The project was overwhelmingly approved.
Meadowglen Drive drainage ditch (after)
The Meadowglen Drive drainage ditch was then enclosed by installing varied sizes of pipes, ditch bottom inlets, yard drains, curb inlets, several structures as well as a pollution control device at the discharge point into Lake Lovely. For ease of installation and to lower total construction costs, High Density Polyethylene (HDPE) pipe was used in lieu of the conventional reinforced concrete pipe (RCP). Enclosing the ditch in this fashion minimized the need for future maintenance by Orange County and eliminates backyard erosion.
The design and construction costs of the project are $77,244 and $525,000 respectively. It took more than 31 months to complete from the inception of the design to the construction.
Drainage on Falkner Road can be characterized as rural. Shallow swales along the road provide some storage for runoff water during and after storm events. Swale drainage of this type is highly dependent upon soil and groundwater conditions that control the rate at which infiltration of water into the ground occurs.
When the rate of rainfall exceeds the soil infiltration capacity, filling of the swale begins. When the volume of the swale has been consumed, overflow to a downstream drainage system is required to prevent flooding of adjacent properties.
In addition to concerns related to storage and evacuation of water, several problems can develop over time with this type of drainage system:
The most serious of the problems on Falkner Road is the elevation of the lots. The finished floor elevations of many residences along the road are only slightly higher than the elevation of the road. The lack of a swale system and driveway dips not properly built in the area prevent proper overflow, therefore resulting in flooding of the structures under severe rainfall conditions (i.e., hurricane or tropical storm).
In order to address the complaints on Falkner Road and in response to many recommendations from many of the residents, Orange County installed ribbon curb along both sides of the road. Although this ribbon curb does not provide any benefit relative to the existing drainage system, some residents believed that it would help the situation and would also serve to make Falkner Road more consistent with nearby roads within the subdivision.
Falkner Road (finished project)
Orange County subsequently developed major improvements to minimize the potential for flooding of residential properties. Drainage inlets and underground storm piping have been constructed along Falkner Road to minimize the potential for flooding. A shallow roadside swale was also established within the roadway right-of-way over the storm pipe, between driveways to collect runoff water at the proposed inlet locations. For any cases where properties are lower than the road, additional small drainage inlets (i.e., yard drains) were installed outside the road right-of-way to collect any runoff water between the house and the road.
The design and construction costs of the project are $64,795 and $255,826 respectively. It took 220 days to complete construction.
These drainage improvements underscore the importance of public involvement. The partnership of easement donations from several residents and neighborhood willingness to sustain inconveniences results in substantially less disruption and disturbance to private property.
The careful planification, programming budget funds, permits, and emphasizing the need for material selection for specific site conditions have resulted in a learning experience on how to handle challenging drainage improvement projects.