The following is Part III of a three part series focusing on the City of Scottsbluff’s 319 grant projects. These projects are designed to reduce impervious cover in parking lots, filtering and infiltrating stormwater runoff. This article will go over project successes. For an overview of the projects, see Part I. For project challenges and lessons learned, see Part II.
In the last article, we went over the challenges of landscaping a hot, harsh urban environment. Now that we have gone over the difficulties of these projects, we are going to outline some of the practices we used that worked well. The following is a list of some of the techniques that were effective and that we will be using in the future:
- Plant Selection- Thanks to the help of the Nebraska Forest Service and the Nebraska Statewide Arboretum, we were able to use a very carefully chosen plant list. This plant list included several tried and true plants for our area, such as catmint, yarrow, jupiter’s beard, butterfly milkweed, and asters, as well as some lesser-known selections, such as thelosperma and plumbago. We will be monitoring these landscapes to see which of these plants do well over time, helping to expand our palette of plants we know to be successful in this area.
- Sedges- While this also refers to plant selection, the unique functionality of our sedges merits them their own bullet point. Because the projects are designed to capture stormwater, and because the soils were in such poor condition when we started our projects, we had several areas that were poorly drained. These were the areas where we planted sedges, some of them which were literally planted in standing water. These sedges have thrived, looking very attractive while serving the very important function of cleaning and filtering stormwater before it reaches the storm drain or is infiltrated into the ground. There are very few plants that do well when exposed to extended periods of standing water; we have had great success with using sedges in these difficult areas.
- Beehive Storm Grate- The previous storm drain was a typical rectangle grate that was flush with the ground. We talked about some of the challenges of mulch in our previous article; one of the other challenges is that it can plug a storm drain. The storm drain we chose for the overflow of our retention area, shown below, is designed to keep from plugging when the water gets deeper and mulch starts floating. After experiencing a few strong thunderstorms, it appears that this design has been very effective at keeping the storm drain open to receive overflowing stormwater runoff.
- Strategic Placement of Hardscape- We allowed several areas throughout the landscape for people to pass through as they were leaving their vehicles. This seems to have cut down on the amount of foot traffic we receive in the landscape itself. Additionally, in an area that was constantly being driven over, we strategically placed a boulder. This not only has aesthetic value, it has completely stopped vehicles from driving over this part of the landscape.
At this time, those are the most noticeable successes that we have seen. We are hoping that over time, using large landscape beds with adequate soil rooting volume for trees will help the trees to be more successful long-term; however, it will be several years before we know for sure if it is a success. We are also hoping to turn off the drip irrigation systems in the future. During their first summer, though, we will be leaving the irrigation on to help the plants establish their root systems. We may have to continue irrigating during extended dry periods. We will also be observing our plants over time to see how they do- watch for future articles outlining specific plant selections that have done well. All in all, perhaps the greatest success has been being able to remove over 9,500 square feet of concrete from our parking lots and replace it with a beautiful, functional landscape that will have great environmental benefits for years to come.