The Valleyist Papers
A COLLECTION OF ESSAYS WRITTEN IN FAVOUR OF THE IMPROVEMENT OF STEPHENS VALLEY
Author – William Ray
Edition 4. Issue 10.
There is one thing all of us in SV have in common – we all see the big construction project for our downtown going on, and we all wonder just what is going on. This month let's try to help some with that yearning for information about the project. While plans are not available to me, it isn’t all that hard to see what is going on presently just by walking around the project.
A few months ago, it appeared that the earthwork portion of the project was going to last throughout the year. It certainly seemed complicated enough to last that long. However, the present work to install underground infrastructure makes the earthwork portion of the project appear mundane. Presently RAWSO Constructors is fully engaged in the work of installing water, sanitary sewer, electric conduits, and the stormwater management system. The stormwater management system is very complicated, and we will spend some time talking about it in this issue.
The hard work of stormwater management began long before RAWSO arrived in SV this spring. Months of exacting professional design work had to be done long before a spoonful of dirt could be excavated, or a foot of pipe could be installed. The challenges faced by the engineering team were many. They needed to design a system of water inlets, mixing boxes, piping, manholes, and other infrastructure to drain off surface water coming from rain events impacting the new SV Downtown and also accommodating runoff from other areas above our new downtown (basically all the land on the east side of Natchez Trace which constitutes the drainage area which must be managed).
It is the management of the stormwater that took lots of thought and calculations. If the task were as simple as just draining rainwater away from the downtown, it would not be so daunting. However, there are a litany of other issues to be dealt with. The system must work today when much of the area is naked earth which has the nasty habit of sending mud into the stormwater system and into the creek that runs through Meriwether Park and eventually into Trace Creek and the Harpeth River. Then it must also work to drain the completed downtown, which will mean nearly 100% coverage of the land by pavement and structures that will convert every drop of rainwater into new runoff. Oh, and it must do everything between now, and when the downtown is completely built, to mitigate damage to everything downstream during the long process of building the homes and commercial buildings that will make up our downtown. All of this is very hard to do.
Few of us were around a decade ago when SV was first proposed, but the signs that remain on fence posts along Sneed Road inform us that SV endured a lot of opposition before was born. It is certain that some of the fears expressed by the opposition were about dramatic negative impacts on the Trace Creek and Harpeth River watersheds. Those might have been legitimate fears had not Williamson and Davidson County governments stipulated that a sophisticated stormwater management system, like the one being installed right before our eyes, be installed as SV grew. For what we can all see now, it appears that everyone is adhering to those stipulations, and that our neighborhood will not negatively impact the watersheds.
The methods chosen to accomplish these objectives are revealing themselves as RAWSO makes daily progress on installation of the stormwater system components. A few decades ago, this project would have been far more simple and totally analog. The creek that went through the downtown area would have simply been enclosed in a culvert, the new streets would have been outfitted with stormwater drains to channel the water to that culvert, and that would have been the whole system. The system being installed before our eyes is vastly more capable and complex.
The existing creek is being re-routed into a piping network that sort of zigzags through the site as it connects to mixing boxes, manholes, and collection piping. It can look a little crazy, but there is clearly genius at work in the design being executed. 
A lot of the zigzagging and mixing boxes are part of a system designed to slow down the runoff and store some of it during a flood event. The design provides a lot of “friction” to slow down the runoff and protect everything downstream.
One of the largest elements of that protection has just been completed on the west side of Stephens
Although Meriwether Park is a lovely feature of our life in SV, it is more a component of the stormwater management system that it is a park. That will become even more evident as the downtown construction progresses. You will note that the park is already getting more dense vegetation along the boundaries of the central creek in anticipation of the new work it will soon be asked to accomplish. The vegetation will also provide protection for the creek banks, and it will add more friction to slow the flow of excess surface water.
Some other new technologies in stormwater management are also apparently coming to our project. Some of the stormwater inlets appear to have active filtering systems to help reduce suspended solids and other compounds like phosphorous and nitrogen (mostly components of the fertilizers we apply to our yards) which might increase biological oxygen demand in the Harpeth and Cumberland Rivers downstream of SV. It isn’t clear to we casual observers yet, but there might also be automated valves and weirs incorporated into the management system that reconfigure themselves based on weather conditions. All of this is state of the art in stormwater management.
Sure, we are all impatient for the downtown to be a reality. Sure, we are mostly tiring of the incessant construction noise. But from what we can see, the results are going to be something astounding. A developer, an engineering firm, excellent construction contractors, and understanding residents are all working together to grow SV intelligently.
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