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HomeMy WebLinkAbout(32a) City Wetlland Report Bridger Meadows_Naiad_Review TQ Response 03-02-2021 Section 32a – Applicant Responses City Wetland Report NAIAD Review Bridger Meadows Neighborhood Development PUD Preliminary Plan Application 20350 Subdivision Preliminary Plat Application 20351 March 2, 2021 Sarah Rosenberg, Associate Planner City of Bozeman 121 N Rouse Ave Bozeman, Mt 59715 RE: Responses to City of Bozeman Review of Bridger Meadows Subdivision Sensitive Areas _________________________________________________________________________________ Dear Sarah, Responses (blue) to City of Bozeman (COB) review of Aquatic Sensitive Areas are below each bulleted review point. • Ms. Bacon notes that the subdivision’s original design had the road east of the lots, a design that would impact about 0.74 acres of wetland and much of the setbacks. The site was redesigned, and the wetland impacts were reduced to 0.078 acres. This current design is shown in Figure 1. Although I commend the reduced impact in the redesigned project, simply juxtaposing the two designs does not adequately show avoidance and minimization. We can assume that there are many problems with the first effort, besides wetland impacts, that would make that design unreasonable (e.g., increase expense of grading and lot values with open area adjacent -vs.- across the street). Avoidance and minimization can and should be an iterative effort. There are five areas where the current design could be altered, and one or more would provide additional avoidance and minimization of impacts to sensitive areas. Please refer to the circled areas in Figure 1 (this figure has been placed at the end of this document). Wetlands have been avoided and impacts minimized by redesigning the project into its current configuration. Decreasing impacts from 0.74 acre to 0.091 acre qualifies as both avoidance and minimization, to the maximum extent practicable. • Area 1 – There is no description of the grading that extends into the setback area in this location. Nor is it labeled on the are Grading and Drainage Plan. Without this explanation, it is difficult to know its purpose or conceive a path to avoid and minimize impacts on the setback. • The impacts in Area 1 are not in a sensitive area and do not impact any existing wetlands. The proposed excavation is the removal of artificially placed fill (an old railroad bed). The fill is being removed to increase the 100-year flood storage volume of the East Gallatin River, to offset loss of flood storage volume in other areas of the site. The Applicant intends to excavate Area 1 down to about the same elevation as the surrounding wetlands, then remove wetland sod/seed mats from impacted wetlands and re-plant them in this area. Wetland plants would very likely re-establish themselves in some or all of Area 1 due to the new conditions (shallower groundwater), resulting in a new wetland area that is larger than the total area of currently proposed wetlands impacts, even at a 50% reduction factor for replacement wetlands. Bridger Meadows Neighborhood March 2, 2021 Applicant Responses City Wetland Report NAIAD Review Page 2 • Area 2 – The grading necessary for the building pad of Lot 4 is the reason for the most extensive wetland impacts, those on Wetland 3 (0.60 acres). Eliminating one lot and reconfiguring the others could avoid this wetland altogether and minimize other impacts to the setback. The Wetland 3 acreage of 0.60 acres is misquoted and is actually 0.060 acres. Area 2 (Wetland 3) impacts were reduced to the extent feasible (from 0.060 to 0.035 acres) by adjusting the Lot 4 lot line. This change also reduced floodplain impacts. Any further reduction of impacts in this area would compromise other goals of the project and of the City, such as the desire for infill development. Removing Lot 4 to protect an additional 1,500 sq. ft. of Wetland 3, which was farmed agricultural land as recently as 2011, is not feasible. Allowing the development to move forward in an economically viable manner allows the Applicant to follow his intent and vision to permanently preserve and enhance almost all of the naturally occurring wetlands on the site, while having homeowners close by with a vested interest in monitoring and preventing the degradation of wetlands and unique wildlife habitat that has occurred in the past on this site. • Area 3 – it appears that moving this utility crossing approximately 50 feet to the SE would avoid 0.01 acres of impact to Wetland 4, All Wetland 4 impacts will be within the 30-foot utility easement, so wetland delineation was not completed beyond those limits. Impacts would be similar east and west of the proposed location. The utilities and easement are located to align sewer with an existing manhole in Boylan Road, so cannot be moved. • Area 4 – By switching the location of the stormwater management with Lot 7, it appears that additional setback impacts could be reduced. The impacts in Area 4 are primarily in an upland area of historically agricultural use. Impacts to existing vegetation extending toward the wetland is necessary to discharge storm water from an underground detention facility. The stormwater facility’s location is set by the low point in the road and cannot be moved west to the area of Lot 7 due to the rise in road elevation. Moving the road’s low point to the west would not allow enough elevation drop for collection, storage, and treatment of all street runoff. • Lastly, Area 5 – The ‘Ground Water Discharge Pipe’ and proposed retention basin outfall could be moved to the east to have the pipe discharge into the upland area, thereby avoiding the impact of 0.008 acres of impact. The Area 5 (Wetland 1) impact, previously required for a groundwater discharge pipe, has been removed from the project along with the pipe. This eliminates ground disturbance within sensitive areas (existing wetlands and floodplain) in Area 5. • Setback Impacts • I do not see any setbacks on Wetland 3 in Exhibit C. It appears that Wetland 3 is connected to the floodway, and its buffer should also extend. Wetland 3 is not an immediately adjacent (i.e., fringe) wetland, therefore per the UDC is not included in the watercourse setback. Whether it is connected to the floodway or not is irrelevant. There is no wetland buffer for the same reason. • Lot 7 has a setback impact but not included in the application. A relaxation from the wetland buffer requirement has been requested with this application. The proposed wetland buffer is shown on the revised Exhibit C and is within the rear building setback area. Bridger Meadows Neighborhood March 2, 2021 Applicant Responses City Wetland Report NAIAD Review Page 3 • Grading setback impacts for the proposed retention basin in the SE corner near Wetland 1 are not in the application. The groundwater pipe has been removed from the project, and all associated impacts to the existing 100-year floodplain and existing wetlands have been eliminated. The ground disturbance area for the retention pond is outside of the watercourse setback, but within the wetland buffer which is acceptable. • I do not see a total area of wetland setback impacts Calculation of watercourse setback impact areas is not required in the UDC so was not provided. There are no impacts within the proposed watercourse setback. This is also true for non-compliant uses within the proposed wetland buffer. • I do not see any plan for the mitigation of these impacts. The proposed watercourse setback does not extend into any of the residential lots or proposed improvements, except re-grading and re-vegetating to mitigate floodplain impacts. The proposed wetland buffer does not extend beyond the rear setback line of any residential lot. Landscaping and minor improvements are allowed within the rear setback and wetland buffer. • No functional assessment. Given wetland impact was reduced through Avoidance and Minimization from 0.74 to 0.091 acre, decrease in wetland function is deemed not a concern by this TerraQuatic Wetland Scientist. Functional Assessments will not be provided. • Sec 38.610.080.A.3.d requires an assessment of cumulative impacts, but I did not see that in this report. No cumulative impacts assessment is provided; no other impacts have occurred as a result from this property owner. • There was a lot of discussion about the ‘defunct stormwater system’ north of the property. The pond to the north is open water, and the relevance of its history may be a concern to the USACOE, but I do not believe it is relevant to City. The stormwater system north of the property is of concern because it is not functioning; sediment has filled the basin and groundwater infiltration has increased downslope of the facility, i.e. Wetland-3 has doubled in size in the last 5 years. • Impacts on Wetland 4 and Wetland 1 are not mentioned in the report. Do not know what this item means. In general impacts are not reviewed within an aquatic resource delineation summary document. • I am not convinced that the buildable area in Lot 4 cannot be reduced to a footprint similar to lot 2. See response above regarding Figure 1, Area 2. Area 2 (Wetland 3) impacts were reduced to the extent feasible (from 0.060 to 0.035 acres) by adjusting the Lot 4 lot line. Further reduction to eliminate all impacts to Wetland 3 would reduce the depth to less than Lot 2. Additionally, the front lot width is much less than Lot 2, so the resulting area within the building setback lines, as well as its triangular shape, would result in a lot that is too small for a typical home consistent with the project. Bridger Meadows Neighborhood March 2, 2021 Applicant Responses City Wetland Report NAIAD Review Page 4 • In Ms. Bacon’s response to 38.30.090.A.5, she states that “City of Bozeman watercourse 50- foot wide setbacks along connected wetlands are greater than federal USACE restrictions.” USACOE has no buffer requirements and leaves this to state and local governments to establish. These are clearly stated in the City Code; therefore, I do not see this statement’s relevance. The item asks if City restrictions are greater, simple answer: Yes. This was just an answer to a question with no expectation regarding relaxation requests. • There is a French drain that is mentioned several times, but I do not see it in the plan submitted with the application. There is an existing French Drain about 8 feet northeast of Bridger Meadows. The previous submittal proposed connecting a new pipe through Bridger Meadows that would discharge collected groundwater into the south end of the Bridger Meadows pond. This new pipe has been deleted from the project. The existing French Drain collects a significant amount of groundwater which discharges continuously into the Boylan Road ditch and into the existing detention basin north of Bridger Meadows. Due to lack of maintenance and/or design issues, the detention outfall path has migrated from its intended discharge to the west and now flows toward and into Bridger Meadows, either creating or greatly expanding Wetland 3 on land that was farmed agricultural land as recently as 2011. The groundwater pipe was shown inaccurately on the previous submittal and has been moved to match the location on the record drawing. • In sec 38.41.130.3 in the review document, Ms. Bacon states that there is no mitigation required for impacts below 0.10 acres. This may be allowable for the USACOE CWA permits; however, I do not see a size limit in the City of Bozeman code. When the USACE enters into the jurisdictional aquatic resources impact mitigation the City does not require additional mitigation requirements. The City does require mitigation ‘negotiation’ for nonjurisdictional (NJ) aquatic resource impacts with the exception of most (if not all) stormwater facilities and true irrigation ditch features. Mitigation quantities and types for impacts to NJ features vary from project to project and depend on myriad aquatic resource characteristics as affected by the proposed development during analysis by City Aquatic Resource Subconsultants. • The review material focuses on impacts in Wetland 3 but reports different numbers than those in the Exhibit B impact table. The review material also reports other impact numbers for Wetland 4 and does not report impacts to Wetland 1. Please review enclosed revised Exhibit B impact map. This map has been submitted to the USACE. Sincerely, Lynn Bacon, PWS TerraQuatic, LLC 614 Lamme Street Bozeman, MT 59715 lbacon@terraquaticllc.com Bridger Meadows Neighborhood March 2, 2021 Applicant Responses City Wetland Report NAIAD Review Page 5 Figure 1. Five specific areas of potential avoidance or minimization.