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Sterling Gulch Phase II & III

Matrix developed and implemented a plan to stabilize Sterling Gulch and its associate tributary. Sterling Gulch is partially located within the Sterling Ranch development. Due to the increased stormwater input, Sterling Gulch required extensive grading and increased vegetative stabilization to minimize the potential for erosion. Matrix’s Ecological Services team assessed approximately 10,125 linear feet of Sterling Gulch and its tributary. Preconstruction soil samples were then collected and analyzed and soil amendment recommendations were developed to provide a sufficient growth medium and ensure successful native revegetation. Based on the soil sampling results and existing plant communities, Matrix developed native seed mixes tailored to the site’s characteristics and design. The team also provided markups on grading plans to include overbank depressions and swales to increase topographic complexity and the overall ecological function of the site.

Matrix was heavily involved during construction, providing oversight of topsoil salvage and preparation, grading, and seeding operations. Following construction of both project phases, the Ecological Services team provided three years of adaptive management monitoring and worked closely with the landscape contractor to achieve a native-dominated and stable vegetation community. During the first year of adaptive management monitoring on Phase II, significant populations of annual noxious weeds were observed, which was likely a result of a noxious weed-dominated seed bank in the existing topsoil. To prevent this issue on the Phase III site, the team recommended a scrape a bury approach to remove the top four inches of topsoil, effectively eliminating the seed bank. As a result, minimal noxious weeds were observed in Phase III following construction.