Cocoa Beach’s downtown was the first to be developed in the 1920s with Minutemen (formerly Cocoa Avenue) as the main street. In the 1950s, drainage infrastructure was installed and over the following decades a gray infrastructure of asphalt, concrete, buildings and parking lots became the streetscape. For over a half century, this downtown drainage has been flowing untreated into a residential canal that leads out to the Banana River Lagoon. This canal is the oldest in the City and considered the poorest quality. There is no vacant land available in downtown to create a convention stormwater pond without demolition.
This improvement treats stormwater by striving to emulate the pre-development rainfall pattern i.e. allowing rain to percolate into the soil where it falls, minimizing surface flow. Tree canopy, rain gardens, pervious pavers and exfiltration is interconnected to transport collected rain to the barrier island soils that allows renourishment of the City’s shallow freshwater aquifer, keeping saltwater intrusion at bay. This stormwater improvement method adds to the barrier island’s natural community through added green infrastructure, much of it native landscape, while significantly restoring the hydrology lost to decades of development. The basin treated by this improvement is 20.3 acres of roadway and downtown adjoining retail shops and restaurants.
- Flood control elements: Exfiltration rain tanks, pervious pavers, rain gardens.
- Waterbody impacted: Banana River Lagoon; Nutrient impairment addressed: nitrogen, phosphorus
- This project replaced a couple of recommended projects in the 2001 Stormwater Master Plan. It addressed areas which were identified for other projects.
- The project is located within the Indian River Basin Banana River Lagoon BMAP. The project addressed the reduction of TN/TP as part of a TMDL. Minutemen Corridor Stormwater Improvement/LID, CB-39.
As part of community improvement, it was designed to be a streetscape project in addition to a stormwater project. Elements such as pavers, wide sidewalks, bike racks, and new benches welcome community members and visitors to this main street corridor. Traffic calming features have not only added more aesthetic appeal, but also made the area safer for pedestrians and cyclists. The rain gardens showcase native coastal plants which beautify and enhance the natural habitat of the area. The project consists of five blocks, each with a slightly different feel as they are for different purposes. From east to west: Block 5 is the beach plaza welcoming residents and tourists alike to the heart of Cocoa Beach. Block 4 consists of restaurants, retail and an art gallery. Block 3 contains City Hall has well as restaurants and retail shops. Blocks 1 and 2 are a combination professional business and residential. These blocks are also passed through to get to the schools, country club, and aquatic center. The project is considered to be part of the Indian River Lagoon National Scenic Byway which is part of Florida Scenic Highways and America’s Byways systems.
- MM Construction Plans
- Plant list has 3 parts- initial plants planted, current plants, and trees. The trees have not changed, however three years post-construction, plant beds were reassessed. Many plants that were initially planted did not thrive in the beds there were planted in. Each rain garden was assessed for how much water it received as well as sun exposure. Due to this, a much wider variety of plants were used in the replanting. Another goal of replanting was to include more Florida natives. Original plants that were thriving were left in place.
Project Funding & Maintenance
Regular maintenance of the rain gardens includes weekly/biweekly bed weeding and trimming depending on the season. We had initially contracted this out, but as the continuing service contracts expired for grounds maintenance, the newer bids came in much higher for fiscal year 2021. The stormwater crew is currently maintaining the beds for weeding and hedge trimming. We also have a small group of volunteers from the nonprofit “Keep Brevard Beautiful” that is adopting blocks 3 and 4 to assist with bed maintenance on a monthly/quarterly basis. The stormwater crew also trims the canopy trees, and the palms as needed (at least biannually). The major replanting which occurred this year (3 years post construction) included soil replacement and pine straw placement as mulch.
The Vac-Tron is utilized to clean the rain garden sediment boxes quarterly. The eastmost boxes which take in the most sediment and floatables, may be cleaned on a more frequent basis as needed. The larger Vactor truck is borrowed from our Water Reclamation department to clean out the rain tank sumps biannually.
We are not currently outsourcing to pay for the care of the rain gardens. We had $7,000 in the FY21 budget to pay for this maintenance. However with the new bids, only one company came in within our budget. Unfortunately, once the company started they realized that the job was much more involved then they initially thought, and they let the account go. (It is important to note that for grounds maintenance continuing services contracts this year, companies bid per area in the City and four companies were contracted with. In this way, we are able to contract different companies for specific jobs based on bid price and performance.) If we choose, we can contract with a company for maintenance, but at a reduced schedule to fit within the budget. Given the bid amounts, this part of the budget has been adjusted for FY22, so that we can resume regular maintenance by an outside company.
Since we are currently not in contract with anyone for rain garden maintenance, the maintenance of the Minutemen BMP components (rain gardens landscaping, rain garden sediment boxes, and rain tank sumps) take approximately 1000+ man-hours per year.
Many forms of community engagement were used during this project: public meetings, business meetings, Cocoa Beach News Network (CBNN) emails, Facebook posts, newspaper articles and project webpage updates. The project had been reviewed by the Planning Board, Land Management Committee, Landscape Committee, and City Commission. During design, interactive public workshops were held at 60% and 90% design in order to get public input on the streetscape portion of the design. (The meetings were publically noticed and all agendas and minutes were published to the City’s website. Businesses that were along the corridor were kept informed of construction process through weekly meetings and emails.
While response was overall positive, the biggest hurdle was ensuring businesses along the corridor were kept as satisfied as possible. Affected businesses were allowed guaranteed pedestrian access and parking throughout construction. In order to accomplish this, one thing that helped was undergoing construction one block at a time. Otherwise, there were luckily alleyways to access the businesses through the back. When construction was completed, businesses were very happy at the aesthetic improvements outside of their doors.
The educational components are still in design. However, they will include at least one cantilevered 24”x48” display highlighting the LID components of the design and the land-water connection. Florida native plants will be highlighted in the garden with their own signs.
Estimated Water Quality and Quantity Benefits
This LID project had the most impressive success with hydraulic efficiency which overall had a retention of 98.5%. Unfortunately, this did not correlate to the same nutrient reduction capabilities.
Altogether, the BMP treatment train produced removal efficiencies of 10% for total nitrogen and 9% for total phosphorus. LID components with a BAM sub-layer always resulted in a greater TN and TP removal efficiency, however this was most pronounced under the pavers in which the BAM reduced the amount of TN 31% more than without BAM, and TP 12% more than without BAM. It is also notable that copper and lead were reduced in all cases, and a reduction of zinc was seen in the exfiltration and pavers, but was increased in the rain gardens (presumably from construction materials).
Problems encountered and lessons learned
Some issues have already been noted above, such as the construction executed in stages and other steps taken to minimize the impact to business. A few more obstacles were encountered, beginning with construction. Due to very old infrastructure in this area, many unknown utilities were discovered when layers of asphalt and concrete were peeled back. When unexpected utilities were discovered, most of the time construction had to be paused and engineered designs reconfigured. The other issue that layers of roadway caused was then matching grades between the new layout and existing adjoining areas- causing nuisance ponding in some ADA pedestrian crossings. Pervious pavement in these areas may be a possible fix, or may be able to be implemented in future designs to avoid a similar issue.
Upon installation, the rain gardens appeared to have a steep drop-off in some areas. To combat this ledge effect, bollards with rope were installed around the gardens. This also helped to keep foot traffic out and the new landscape intact. As the gardens have grown in, we have kept the bollards on the road side, however have removed them from the sidewalk side as we had many issues with people knocking them over and they continually needed to be fixed. We did not want to concrete them in as this would take up a lot more room within the garden bed itself. A better option would have been having bollards included in the initial design to be more permanent structures and so that the space they take up could be accounted for.
The gardens had other issues such as uneven flow into them from the pre-treatment sediment/sump boxes, causing heavy erosion to take place in one area of each garden. In order to diffuse the inflow, curb cuts were installed with rock flumes under them allowing water to enter the gardens through multiple points. The resilience of the plant species chosen was discussed above, but another landscape type issue encounter was mulch which floated away during heavy rain events. Pine bark was initially used in the gardens as mulch, however this same bark would then be found all over sidewalks and roads after heavy rain events. Prior to the plant renourishment previously discussed, the beds were raked out of this mulch, soil was brought up to an acceptable level (as some had also been washed away over the past few years), new plants were planted, and pine straw was used on the beds. We have had a couple of large rain events and so far no pine straw has been misplaced. The pine straw appears to be a much better option as it mats down, making it harder to float away.
Finally, in regard to the BAM efficiency not being as high as anticipated- lower nitrogen reduction may be due to the low concentrations of NOx and SRP in runoff. This could have limited the ability of the BAM to provide significant nitrogen loading reductions. In the future, the presence of sufficient NOx concentrations for denitrifications may need to be field verified prior to the construction of a system with BAM.