DENHAM SPRINGS - Modern urban development models consider 'concrete' and 'asphalt' a dirty word - a means to an end, but not something that should be used in abundance. Why? For reasons that have become extremely important to local residents - their effect on drainage.
Permeable surfaces and storm water runoff were the buzz words at a presentation to a small crowd in city hall Monday morning. LSU agriculture and engineering students took time away from finals study to present their semester-long projects on potential improvements to various study areas just north of the railroad tracks in Denham Springs.
But the proposed improvements were not just aesthetic in nature - they had economic and drainage benefits as well.
Both groups were tasked with analysis of the Long Slash Branch of the Amite River as well as drainage, road infrastructure, and aesthetic improvements to the Downtown Antique District.
The resulting presentations painted a picture of a 'new-look' area that spanned almost the length of the Long Slash, from the former location of Angelle Concrete all the way to Spring Park. Every presentation increased green space, tree capacity, and grass areas for storm water runoff collection. Many also included spaces that would be designed for water to fill in the event of a large storm.
According to several results from the engineering group, even minor increases in the green space to create permeable areas that absorb water runoff can decrease storm water levels by as much as 50%.
The first project, titled 'Vegetated Drainage,' analyzed Long Slash Branch's canal itself, which is made almost entirely of concrete in areas where it is exposed. There are some areas which are buried. The presentation suggested that the canal itself would benefit from a removal of most of the concrete, to be replaced with various tiers of vegetation - all of which were designed to flood, if necessary.
The second project, 'Sponge Park,' saw a complete re-design of the old Angelle Concrete complex into an urban park theme, with a water-based amphitheater (designed to hold water, if necessary) with a splash pad, and a large retention pond for fishing. There would be spaces for food trucks and vendors spread throughout the park, as well as sports courts, and a market.
Third, 'Creek Park' would rest directly north of the district, near the southern border of what will soon be a new campus for Denham Springs Elementary. The presenter noted that the Centerville Street intersection with Range Avenue and Hummell is confusing, suggesting a large, two-lane roundabout with a park in the middle. Parks would also line a 'green' canal and would be pedestrian friendly.
Denham Springs City Hall's parking area, which is mostly concrete, would see a complete remodel in the fourth project, dubbed 'Green Parking Lot.' Not only did the presenter suggest that parking spaces be reduced, but that those reclaimed spaced be used for green space - she even threw in a 'cover' structure that could collect rainwater and distribute it.
The fifth project again focused on the Centerville intersection and installing a roundabout, also with a garden. The presenter also introduced bioswales, which are raised landscape elements that are meant to slow storm water runoff and collect chemicals and pollutants. They regularly come in the form of street side planters, which the presenter also suggested could slow down traffic.
The next project drew the most attention from the audience. In it, the stand-in presenter - as the project manager had a job interview - described the idea of 'Floodable Parks' at Spring Park and as a replacement for the old First Baptist Church, now condemned by FEMA. If built, the floodable parks would hold a 'small stadium' worth of water inside small pools that would also act as play areas. The grass would be kept medium to high to stop and hold more water.
Finally, a presenter who talked to anyone and everyone at Springfest and came back for the encore stated that he was 'struck' by the quaintness of Denham Springs upon his first arrival. His project was based on 'Tactical Urbanism' focused on bioswales, pedestrian experiences, and much more green space.
"A pedestrian experience to reflect the history of downtown Denham Springs," the presenter said.
The engineering students elaborated on permeable surfaces, including roads, that are made of specific materials that help absorb storm water. What piqued the interest of many of the career engineers in the room was the identification of two choke point spots within the Long Slash Branch drainage canal and underground tunnel, which were disturbing the flow of water.
One group made note that there is an eight-foot drop in elevation at the top of the ridge near the Baptist Church and the parking lot.
According to Mayor Gerard Landry, some of the items were immediately actionable - including work on those choke points - while others would need state, federal, and grant monies to come to fruition.
Some were, also, just pie in the sky.
"The permeable streets sound great, until you start talking about things like sand and dirt getting caught in those permeable surfaces. How do you clean them?" the mayor asked rhetorically. "We'll need to see more data on that."
One student brought a quick silence to the room with an off-handed comment on the state of flooding in Denham Springs.
"We decided to go with 25-year models because it accurately reflects the drainage," she began, "everyone knows in 100-year models the Amite reverses and flows into Denham Springs."
The comment brought to light the fact that, while the city is working on their drainage needs and situation, they remain part of a regional drainage plan.