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HomeMy WebLinkAboutAdditional Subd. Preliminary Plat Supplements 04-24-2020 Additional Subdivision Preliminary Plat Supplements Page 1 οf 7 Additional Subdivision Preliminary Plat Supplements Norton East Ranch Subdivision, Phase 5 1. Surface Water The Norton Ranch Surface Water Exhibit illustrates the boundaries of surface waters and wetlands that currently exist within the Norton Ranch East, Phase 5 boundary. These surface water and wetland resources are described in the following narrative. They include: • A preservation wetland located along the east boundary of the project and protected in perpetuity by a Covenant of Dedication. • A temporary drain ditch excavated in January 2015 along the north property boundary. • An existing temporary retention located in the southwest corner of the property. Aajker Creek is located outside the west property boundary although the 50-foot watercourse setback extends across the west boundary into the Norton Ranch East, Phase 5 boundary. Aajker Creek will be protected from development by 50-foot watercourse setbacks in accordance with Section 38.23.100 of the City of Bozeman UDC. Norton East Ranch Subdivision was originally permitted by the USACE under Reference Number NWO-2007-1084-MTH, authorized on April 28, 2008. Morrison-Maierle, Inc. Environmental Services Group completed the original delineation of waterways and wetlands on the 245.6-acre parcel owned by Norton Properties, LLC, on October 13 and 14, 2006. A permit amendment dated October 18, 2016, authorized the installation of a new drain tile located south of Fallon Street. The drain tile was installed parallel to the south boundary in April 2017 to prevent groundwater from surfacing via a broken subsurface drain tile that had been installed in the 1970’s for agricultural purposes. The historic drain tile located near the south boundary was broken at the beginning of construction activities on Norton East in 2010. The broken drain tile resulted in groundwater surfacing at an abandoned spring box, which ultimately flooded Phase 5 of the Norton property and the adjacent Lakes property located at the north boundary where the preservation wetland W-5-05 previously terminated. Before the drain tile was installed in 2017, surface water from the broken drain tile on Norton East was collected in a small ditch excavated in an area previously classified as upland that diverted water from the spring box to the preservation wetland. The excess surface water flooded the Lakes property accumulating in a pond located just north of the north property boundary with Norton. Todd Tillinger of the USACE stated during a March 2014 meeting in Helena that the Lakes could take measures to prevent the overflow from Norton from entering their property. A temporary trench was excavated in upland at the northwest edge of the preservation wetland to divert surface water west on Norton East property to Aajker Creek, intercepting the surface water flow before it crossed the boundary to the Lakes. The trench excavated from the edge of the preservation wetland to Aajker Creek had the intended result of draining the excess surface water and pond on the Lakes property. The drain tile installed Additional Subdivision Preliminary Plat Supplements Page 2 οf 7 at Fallon Street in April 17, 2017, currently collects and diverts groundwater from the south property boundary to the discharge point on Aajker Creek, which is located west of the west property boundary for Norton.. The 2017 drain tile was installed to prevent groundwater from surfacing from the broken historic drain tiles. Because over five years had elapsed since the 2006 delineation, the City of Bozeman required a new wetland delineation of Phase 5 in 2018, which included the preservation wetland. A 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 submitted to the City in 2019. The 2018 delineation results indicated that the edges of the preservation mitigation wetland had expanded since 2006. This was the result of excess surface water from the broken drain tile that has since been diverted to Aajker Creek via a new drain tile and dewatering activities that have since been terminated. A request for a new jurisdictional status determination for the preservation wetland was submitted to Tim McNew with the USACE on October 21, 2019. The 2019 plat layout will not impact the preservation wetland but it will impact the wetland fringe identified in 2018 that has developed since 2010 around the perimeter of the preservation wetland. If the preservation wetland and adjacent wetland fringe is classified as non-jurisdictional, impacts to the expanded wetland fringe will not require a 404 permit. If the preservation wetland and adjacent wetland fringe are determined to be jurisdictional, a 404 permit will be required unless wetland impacts to the expanded wetland fringe are avoided. The 2018 data forms, USGS, NWI, aerial maps, and JD form were included with the JD request. The project history was also included with this submittal. Google Earth maps from 1995 to 2014 showed the transition of the area prior to and during construction. The temporary drain ditch excavated in January 2015 at the northwest end of the preservation wetland and parallel to the north property boundary was dug to prevent surface water from inundating the Lakes subdivision to the north. Several permanent solutions have since been implemented sitewide to address the flooding issues that started in 2010. The excess overland surface water flow on the Norton property has been eliminated. A subsurface drain tile has been installed at the south property boundary, the temporary ditch excavated between the historic spring box and preservation wetland has been abandoned and filled, and the dewatering activities have been terminated. The temporary drainage ditch between the preservation wetland and Aajker Creek at the north property boundary is no longer necessary and has been abandoned. Tim McNew has indicated that the temporary ditch channel and area surrounding the ditch must be reviewed during the growing season in 2020 to confirm that the ditch no longer exhibits wetland characteristics. The area was identified as wetland in the 2018 delineation although no test pits were excavated in the area. The drainage ditch was dry in October 2018. Potential wetland characteristics will be evaluated during the growing season 2020. If any one of the wetland criteria is not present, the ditch will be classified as a non-wetland, which will confirm that there are no WUS downgradient of the preservation wetland and expanded Additional Subdivision Preliminary Plat Supplements Page 3 οf 7 wetland fringe. The preservation wetland will then meet the criteria for a non-jurisdictional wetland, and, consequently, the expanded wetland buffer zone. Non-jurisdictional wetlands are regulated by the City of Bozeman. The preservation wetland will be enhanced with trees and shrubs to develop structural diversity as illustrated in the Norton Ranch Landscape Plans, which were designed according to the City of Bozeman Municipal Code. There is an existing retention pond located just north of Babcock Road. This retention pond was installed knowing that it was going to be relocated to the northwest corner of Phase 5 and is to be converted to a detention pond. The pond has been sized to accommodate the existing runoff currently flowing to the temporary retention pond from Phase 3 as well as the additional runoff produced from the Phase 5 development. Please refer to the Stormwater Design Report for more information on the proposed detention pond. 2. Floodplains (Waived) There are no designated floodplains on or immediately adjacent to this site. 3. Groundwater The Geotechnical Investigation Report (Appendix C) for Phase 5 encountered groundwater at depths varying from 3.5 to 5.5 feet below ground surface. The seasonally high groundwater was measured during the spring of 2018. Groundwater levels were determined to be 0.5’ to 2’ below ground surface (please refer to the groundwater monitoring data provided in Appendix C). Shallow groundwater elevations have been encountered throughout the Norton East Ranch Subdivision. The developer is aware of these elevations and all structures are constructed as slab-on-grade. The infrastructure plans for this development will account for the high groundwater condition on site. All streets will be constructed above existing grade to ensure all stormwater ponds are installed above the SHGWL. Dewatering for utility installations and foundation construction is expected and will be accounted for in any construction permits. Crawl space and basement foundations are not recommended within this subdivision – a note is included on the plat with this recommendation. 4. Geology, Soils and Slope No unusual geological features are present on the subdivision site. On December 11, 2017 Noah J. Schaible, E.I., of C&H Engineering visited the site to conduct a subsurface soils investigation. The subsurface soils investigation consisted of examining eleven exploratory test pit excavations. The eleven test pits excavated for the field investigation exhibited nearly identical soil profiles. The first soil horizon encountered in each exploratory test pit was a Silty Clay Organic Soil of low plasticity (OL). The second soil horizon encountered in each exploratory excavation was High Plasticity Clay (Fat Clay) (CH). The third soil horizon encountered in each exploratory excavations was a Poorly Graded Gravel with Sand and Cobbles (GP). The geotechnical investigation report is included in Appendix C of this Additional Subdivision Preliminary Plat Supplements Page 4 οf 7 submittal. This report details the soils encountered on site and provides recommendations for infrastructure and foundation designs. 5. Vegetation The entire Norton East Ranch Subdivision went through a mitigation wetland permitting process in 2007. The mitigation wetland is located to the east of Phase 5 and within the proposed Park in the northeast corner of the site. There is an existing perpetual conservation easement surrounding the wetland and therefore the wetland will not be impacted by the development of Phase 5. The summary report and conservation easement documents are included in Appendix E. 6. Wildlife (Waived) No critical wildlife species or habitats are known to be found on this property. An email was sent to Julie Cunningham of Montana Fish, Wildlife, and Parks on February 7, 2018 asking her to comment on the proposed subdivision, however no response was received. The letter that was sent out is included in Appendix D of this submittal. Ms. Cunningham provided the following comment on Phase 4 of Norton East Ranch Subdivision in September of 2017, “Although I have seen mule deer in this vicinity, it is not in critical winter range and it is in an urban matrix surrounded by other developments. Therefore, I have no major concerns related to wildlife impact from this proposed development.” Phase 5 is in the vicinity of Phase 4 and similar wildlife conditions exist. 7. Historical Features (Waived) There are no known historical features located within the project. 8. Agriculture (Waived) The property is not a viable farm unit. 9. Agricultural Water User Facilities There are no active agricultural water user facilities located within this proposed development.. 10. Water and Sewer Water Supply Water for domestic use and fire protection will be provided by connections to the City of Bozeman water system. The proposed water mains will connect to the existing water main in Babcock Street. Please see the Water and Sewer Design Report in Appendix A for more Additional Subdivision Preliminary Plat Supplements Page 5 οf 7 information. Water rights or cash-in-lieu thereof, will be transferred with final plat. Sanitary Sewer Sanitary sewer service will be provided through connection to the City of Bozeman’s existing sanitary sewer collection system. The sewer system will connect to the existing Norton Ranch Lift Station at the proposed northern terminus of Laurel Parkway. From there, sanitary sewage will be conveyed to and treated at the City of Bozeman’s Water Reclamation Facility. Please see the Water and Sewer Design Report in Appendix A for more information. 11. Storm Water Management Storm water within the subdivision will be conveyed via surface gutter flow to curb inlets, then underground via storm drain piping to a stormwater detention pond located in Park 5A. Please see the Stormwater Design Report in Appendix B for more information. 12. Streets, Roads, and Alleys A Traffic Impact Study has been completed for this project and is included in Appendix F of this submittal. The proposed Subdivision has legal access to Laurel Parkway and West Babcock Street. The proposed roads will match the established (existing) street grid structure and be within dedicated 60-ft wide right-of-way, with the exception of Laurel Parkway which is a collector street and therefore has a 90-ft wide right-of-way. Sidewalks will provide pedestrian circulation within the subdivision In addition, a gravel trail system will run along the perimeter of the subdivision providing access to Phases 1-4 of Norton Ranch Subdivision to the south and the future Lakes at Valley West Subdivision to the north. Road maintenance for all streets will be provided by the City of Bozeman after the improvements have been accepted by the City. Erosion and siltation control will be exercised during construction by using the appropriate best management practices as outlined in “Montana Sediment and Erosion Control Manual” (May 1993) prepared by the MDEQ Water Quality Bureau. 13. Utilities Standard 10-ft front yard utility easements are provided across all lots. Letters requesting comments on their ability to service this subdivision have been sent to the following service providers: Republic Services of Montana, American Medical Response, Bozeman Deaconess Hospital, Bozeman Public School District, Charter Communications, NorthWestern Energy, CenturyLink, Streamline Transit, and the United States Postal Service. Response letters from all of those who chose to comment are enclosed in Appendix C. Additional Subdivision Preliminary Plat Supplements Page 6 οf 7 14. Educational Facilities A letter was sent to Todd Swinehart, P.E., Director of Facilities, Bozeman Public Schools. A copy of the letter and the response are enclosed in Appendix C. 15. Land Use Norton East Ranch Subdivision, Phase 5 is proposed as a 148-lot subdivision which includes 14 affordable housing lots (townhome or single household), 124 single household residential lots, 5 common open space lots, and 5 park lots. The proposed preliminary plat displays the locations of the proposed land uses. 16. Parks and Recreation Facilities The proposed development will use existing parkland dedications from Norton East Ranch Subdivision, Phases 1-4, as well as the proposed Wetland Park in the northeast corner of the subdivision, the proposed Park in the northwest corner of the subdivision, and the proposed linear park along the western edge to satisfy Parkland requirements. The master Parkland Tracking Table is included on the conditions of approval sheet of the preliminary plat application and with the Norton Ranch Subdivision, Phase 5A Master Park Plan. A playground and parking lot is provided within the wetland park and a trail will connect the wetland park in the northeast corner to the park in the northwest corner. A trail running within the open space lots along the west side of the subdivision will connect to the existing trail along the western boundary of Phase 3B. This trail will eventually span from Huffine Lane to Durston Road. There will be an excess of 1.97 acres of parkland after Phase 5 is developed. Please see the enclosed Master Park Plan in Appendix G for details on the proposed Parks. 17. Neighborhood Center Plan (Waived) The Norton East Ranch Subdivision Neighborhood Center has already been installed and is located at the southeast corner of Babcock and Laurel Parkway. The entirety of Phase 5 is within one-half mile of this existing neighborhood center, satisfying Section 38.23.020 of the Bozeman Municipal Code. Pedestrian infrastructure is already installed around the neighborhood center to connect the neighborhood center to Phases 1-4 of Norton Ranch Subdivision. The sidewalks proposed along the streets with Phase 5 will provide the connection from Phase 5 to the neighborhood center, as well as the gravel trail proposed on the west boundary of Phase 5. The Neighborhood Center Plan is shown below. The Center includes a pavilion with a BBQ area, picnic tables, benches, dog waste stations, and lawn areas for active recreation. Additional Subdivision Preliminary Plat Supplements Page 7 οf 7 18. Lighting Plan The street lights on Laurel Parkway are considered to have a low pedestrian conflict and will continue with 250-300 ft spacing (or at intersections) and a lumen output range of 8,300-8,600 (25-30 ft mounting height). Street lights with a lumen output range of 10,000-10,3000 (25-30 ft mounting height) will be included at the proposed local street intersections. A Special Improvement Lighting District will be created after preliminary plat approval and before the final plat application. 19. Affordable Housing The developer has identified an area within its contiguous ownership for development of affordable homes to meet the City’s affordable housing requirements. This area is ideally suited for the development. Please refer to Appendix H for more information on the affordable housing plan. 20. Miscellaneous (Waived) No additional impacts or hazards are anticipated.