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HomeMy WebLinkAboutApp. E. - 2019 Cover Letter 04-24-2020 VA LTGHN Environmental Services 406-586-6909•Cell:406-581-0655-bvaughn@montana.com 8353 Saddle Mountain Road •Bozeman,Montana 59715 Attn: Timothy McNew US Army Corps of Engineers Helena Regulatory Office 10 West 15t'Street,Suite 2200 Helena,Montana 59626-0014 Re: JD request for preservation wetland NWO-MTH-2007—01084,Norton East Ranch October 21,2019 Dear Tim This is a request for a jurisdictional status determination for the preservation wetland protected under a Covenant of Dedication i p on for the original 2007 Ind1v>dual Permit NWO-2007-01084. Kevin Spencer, owner of Norton East Ranch, submitted the preliminary plat application for Phase 5 of Norton East Ranch in 2018. The City Planner required a new wetland delineation although the development was not going to impact the reservation wetland or an jurisdictional p y wetlands. A J wetland delineation was completed on the Norton East Ranch land north of West Babcock Street between September 14 and October 5, 2018, using methodology developed by the USACE and other federal agencies for implementation of Section 404 of the Clean Water Act. The delineation results were not submitted to the City until 2019. The 2018 delineation result indicated that the preservation mitigation wetland had expanded since 2006. This was the result of several upgradient sources of water that have since been abandoned or diverted to a french drain installed at the south end of the property. The 2019 plat layout will not impact the preservation wetland but it will impact the non- jurisdictional wetland area that has developed since 2010 around the perimeter of the preservation wetland. There have been no changes to the area downgradient of the preservation wetland. There are no downgradient waters of the US north of the preservation wetland or connected to the preservation wetland. The data forms, USGS,NWI, aerial maps, and JD form are included with this submittal. The project history is also included with this submittal. Google Earth maps from 1995 to 2014 show the transition of the area prior to and during construction. Delineation procedures involved a review of existing site-specific information and completion of an onsite field investigation based on guidelines for the Routine Determination Method presented in the Field Guide for Wetland Delineation and the Regional Supplement to the Corps of Engineers Mo untains,ountains, Valleys, and Coast Region. Vegetation Y � etation indicator status for this investigation� g m etigation was derived from the Western Mountains, Valleys, and Coast 2016 Regional Wetland Plant List. Taxonomic references included Dorn 1984, Hitchcock 1971, Lackschewitz 1991, and Lesica and Husby 2001. Eleven test pits were excavated throughout Phase 5 to determine the wetland boundaries based on conformance with the USACE wetland criteria for plants, soil, and hydrology. The wetland data was entered on the eleven Wetland Determination Data Forms included with this submittal. Photographs taken during the 2018 wetland delineation field investigation are also included. The 2018 wetland delineation boundaries and test pit locations are shown on the enclosed Wetland Delineation Exhibit (EXI) provided by C&H Engineering. Included on the exhibit are the original 2006 wetland delineation boundaries showing the 8.64-acre preservation wetland,the 25-foot upland buffer, and the meets and bounds of the area protected by the Covenant of Dedication signed and recorded on April 11,2008. The preservation of the non jurisdictional wetland and upland buffer and the drafting of the Covenant of Dedication protecting the wetland in perpetuity were conditions of the original 2007 Individual permit for Norton East Ranch. The preservation wetland is still considered non jurisdictional based on the lack of a permanent downgradient surface water connection or significant nexus to a water of the US. There have been no unapproved impacts to the mitigation wetland since it was created in 2007. The easement for Laurel Glen Parkway across the mitigation wetland was shown in the Covenant of Dedication. The road crossing the preservation wetland has been constructed within the past five years. A temporary drain ditch was excavated in January 2015 at the north end of the preservation wetland parallel to the north property boundary to prevent surface water from inundating the Lakes Subdivision to the north (see enclosed Photo 8.0 from March 2015). Several permanent solutions have since been implemented sitewide to address the flooding issues. The temporary drainage ditch is no longer necessary and has been abandoned. A sub-surface draintile has been installed at the south ro property rty boundary, the temporary ditch excavated between the historic spring box and P g preservation wetland has been abandoned and filled, and the dewatering activities have ceased. The following paragraphs detail the flooding issues that have occurred sitewide since construction began in 2010. The wetland boundaries of the original preservation wetland expanded west of Laurel Parkway between 2010 and 2014, as shown on the 2018 wetland exhibit. The recent wetland expansion was the result of three temporary and artificial sources of surface water that occurred after Norton East Subdivision construction began in 2010. The historic landowner prior to Kevin Spencer of Norton E Ranch had installed two drain tiles within the parcel to reduce groundwater levels to facilitate hay cultivation. The underground drain tiles were broken during construction in 2010, which resulted in groundwater surfacing from the underground pipe to an historic spring box located near the south property boundary. The spring box had been abandoned and dry until the drain tile was broken. The outflow from the spring box coupled with dewatering activities created flooding sitewide. A ditch was excavated in upland by the contractors from the south boundary to the west edge of the preservation wetland,continuing north to the adjacent property. The excess surface water resulted in flooding on the property to the north,the Lakes at Valley West, which created a pond and channel in uplands that were slated for development. A temporary drainage trench was excavated in 2015 at the northwest edge of the preservation wetland to divert excess surface water on Norton East property to Aajker Creek before it crossed the boundary to Valley West. The drainage ditch excavation was completed after a meeting between the Lakes owner Greg Stratton, Barbara Vaughn, and Todd Tillinger, director of the USACE, in March 2014. The drainage ditch was intended to be a temporary solution to allow the Lakes development to proceed until the draintile system on the Norton property could be installed. The drainage ditch at the north property boundary was dry during July 2018 and has been abandoned permanently. The surface water sources that created the westward expansion of the wetland have been terminated. The draintile system was installed at Fallon Street near the south property boundary to collect groundwater and divert it offsite to Aajker Creek. The location of the 12-inch draintile installed by March 18, 2017, was shown on the Phase 4 plans. A groundwater model showing the zone of influence was completed by Michael Nicklin to obtain the 404 permit authorization. The October 18, 2016, Nationwide 29 permit authorization (NWO-2007-1084-MTH), for the offsite discharge of groundwater from the draintile to Aajker Creek was provided to the City. The non jurisdictional wetland area west of the west boundary of the preservation wetland developed between 2010 and 2014 as a result of temporary and artificial sources of surface water. The i water sources have been terminated. The expanded wetland area exhibits marginal wetland conditions dominated by field meadow foxtail (Alopecurus pratensis — FAC), reed canary grass (Phalaris arundinacea—FACW), Canadian thistle (Cirsium arvense—FAC), field sow thistle (Sonchus arvensis —FACU),and smooth brome(Bromus inermis—UPL). The soil in the wetland test pits was dominated by black silt clay with redox features, depleted matrix, or depleted dark surface. The wetland test pits generally displayed saturation to the ground surface, saturation at 18 inches below the ground surface, high ground water table,and geomorphic position. The supporting wetland hydrology for the expanded palustrine wetland no longer exists and the functional value of the newly developed wetland is low based on the lack of structural and plant diversity, lack of water, and prevalence of invasive species. There is no value to reusing the field meadow foxtail and reed canary grass sod, which are both aggressive dominant species. Trees and shrubs will be planted in the north half of the preservation wetland. Please contact my office if you require further information. i Sincerely, Barbara Vaughn Environmental Engineer,MS Cc: Kevin Spencer,Norton East Ranch LLC Matt Hausauer,C&H Engineering Enclosures: Wetland Determination Data Forms 2018 Site Photos Wetland Delineation Exhibit—EXl I