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Letter from Kimley-Horn to Army Corps of Engineers 03-07-2013Kimley -Horn and Associates, Inc. March 7. 2013 Mr. Michael Setering Army Corps of Engineers, Regulatory Branch 180 East 5`s Street, Suite 700 St. Paul, MN 55101 -1678 Re: TH 101- Lyman Boulevard to Pioneer Trail (2011- 02756 -MTS) Dear Mr. Setering: ■ Suite 238N 2550 University Avenue West St. Paul, Minnesota 55114 Thank you for meeting with us regarding your evaluation of the permit application from the City of Chanhassen for the proposed TH 101 reconstruction project between Lyman Boulevard and Pioneer Trail. We have prepared the attached additional information in response to our meeting on February 27, and your February 4, 2013 letter requesting additional information regarding the need for the trail along the west side of TH 101, and the location of storm pond 3. The 404(b)(1) guidelines have been reviewed in preparing this additional information. Based on the City's comprehensive review of environmental impacts of this project, it maintains that the selected alternative results in the least environmentally damaging alternative given the other alternatives evaluated do not meet the needs of the project and other regulatory requirements. If you have any questions or require any further information, please give me a call (651- 6434 -0455) as the construction bids will be received in March Thank you again for your review of this project. Sincerely, KIMLEY -HORN AND ASSOCIATES Beth Kunkel, CWD Associate Cc: Paul Oehme, City of Chanhassen Jon Horn, Kimley -Horn Attachment: Additional alternatives information TEL 6516454197 TH 101 — Lyman Boulevard to Pioneer Trail (2011- 02756 -MTS) March 7, 2013 TH 101 Trail Alternatives — Proposed trail on west side of TH 101 As stated in the EA and concluded in the FONSI, the trail on the east side of TH 101 is part of the Chanhassen Comprehensive Plan (Comp Plan), and the trail on the west side of TH 101 and tunnel are called for by the Metropolitan Council Regional Trail Plan. Purpose: Pedestrian and bicycle safety are the primary reason for constructing trails on both sides of the roadway. There are presently 20 homes on 96h Street that need safe access to Bandimere Park and the regional/city system. The city has identified in its Comp Plan the expansion of residential development in the current open space west of TH 101 (Exhibit 1). The number of trail users in the future that want to cross from west to east across TH l01could be significant once the residential development occurs, with up to 400 new residences being added west of TH 101. Given the curves and hills on this alignment, crossing the corridor by pedestrians at -grade is not safe, even in the improved condition. The sight distance will be improved by flattening some of the curves and hills, however, curves and hills will remain. The corridor is also being widened from two lanes to four lanes, plus turn lanes at intersections. Therefore, the time to cross the roadway will double due to increased width. Safety concerns were the primary reasons why federal funding was approved for a tunnel underpass, to allow residents west of the road to safely access trails and parks east of the road. The tunnel is to provide access not only for current residents, but for future users as well. Avoidance Alternatives: Tunnel options: The trail is needed on the west side of the road to allow pedestrians on the west side of the road access to the underpass. Other locations for the underpass were considered, however, due to grades and water table elevations, tunnel locations nearer to Wetland 4 were not feasible. A tunnel crossing would consist of a large box culvert (14 feet wide by 12 feet high) with a minimum of 2 feet of cover between the top of box and road surface. To avoid trail fill through the wetland, connecting the west side road users to the park, an underpass location anywhere between 96h Street and the park entrance would have been acceptable for current users. However, due to the water table/wetland elevation on the west side of this segment, and the high ridge and park boundary (potential Section 4(1) impacts) on the east side of the segment, there was only a small segment of TH 101 near the park entrance that provided a feasible crossing option. With the water table near elevation 880, a tunnel could not be engineered to fit without raising the road elevation to keep the tunnel bottom adequately above the water table, which in turn would have had greater impacts to the wetlands, right -of -way and project costs. Additionally, given the location of the ballfields within the park, impacts to park property would have required significant replacement costs (due to the elevation difference) which would not have been approved by FHWA given the Section 4(t) impact. Bridge option: Similar to the tunnel, a bridge option is also dependent on topography. Generally the east side of the road is 10 -15 feet higher than the road, and the west side is 10 -15 feet lower than the road. The height of a bridge above the road would need to be 15 to 20 feet (depending on arch of bridge) for vehicle clearance. As a result neither an underpass nor overpass were reasonable in other locations due to the expanded footprint (swing out of trail for underpass; helix ramp for bridge) of impact on at least one side of the road to tie the bridge into the existing grade (30+ foot difference between bridge and existing grade). Therefore, the only area available to construct a grade - separated crossing based on topography /water table was near the park entrance. The final configuration (location and skew) of the trail tunnel was developed with input from landowners to minimize the taking of a number of large oak trees. No trail on west side: Alternatives were considered to avoid the trail through Wetland 4 by routing users south to Pioneer Trail, to cross at the signalized intersection, then back north on the east side trail. This may avoid the 0.3 acres of trail impact to the wetland, however does nothing to improve pedestrian crossing safety, since the distance for this "detour" would add 0.5 miles to cross the road (quarter mile each TH 101 —Lyman Boulevard to Pioneer Trail (2011- 02756 -MTS) March 7, 2013 direction). In reality, most people would not go an extra half -mile out of their way just to cross the road. Just last year a child on a bike was struck and killed by a car when attempting to cross a four -lane segment of TH101 to the north of this segment. Boardwalk option: A boardwalk type structure was considered as an alternative to placing fill in the wetland to accommodate a trail on the west side through the wetland area. MnDOT design requirements for trails/boardwalks include: Longitudinal grades not to exceed 5% Cross slopes not to exceed 2% 10 foot wide trail, with 2 foot clear zone on each side (14 foot total width) The trail and roadway grades are roughly 10 feet above the elevation of the wetland, between W. 96h Street and the southern limits of Bandimere Park, where the roadway grading conflicts with the delineated wetland limits (approximately 1,000 linear feet). Due to this severe change in elevation, minimum 250 foot long ramps (assuming that the existing grade varies) would need to be constructed at each end of the conflict area to transition from the roadway trail grade to the grade of the boardwalk. The starting points of the ramps would be limited to the storm water pond locations. Ultimately, this results in a short and expensive boardwalk that creates unnecessary bicycle hazards due to a rough riding surface, additional barrier rail requirements, and undesirable maintenance requirements, all at increased costs to the city. The construction of an elevated boardwalk at the roadway grade level was also considered in the wetland area. This would require a pier- supported boardwalk (bridge) with a railing along the outside edge of the boardwallL . The total length of the elevated boardwalk/bridge would be approximately 1,000 feet and it would have an estimated construction cost of approximately $1,000,000. While a majority of the overall project costs are being financed with federal and state funds, the elevated boardwalk/bridge would not be eligible for these funds. The City of Chanhassen would be responsible for the additional elevated boardwalk costs which would increase their project contribution from approximately $825,000 to $1,825,000. This option was not further considered due to safety, long term maintenance of the boardwalk/bridge, and cost. Minimization Measures: Because the western trail is required for user safety, and practicable alternatives are not available, the trail impact area has been minimized through a number of design changes along the wetland. These included: • reduced the boulevard between the road and trail from 8 feet to 6 feet • narrowed the roadway center median from 16 feet to 4 feet • increased side slopes adjacent to Wetland 4 from 1:3 to 1:2 • placed trail in the area temporarily impacted by road surcharge to minimize the area disturbed It is estimated that these measures already reduced the wetland impact at this location by nearly 0.3 acres. The road could not be shifted further east due to topography (steep upslope) and park limits. Exhibit 1 shows the location of the future development with respect to the Pioneer Trail and W. 96ih Street intersections. Conclusion: Based on the above facts, the DNR was convinced that the trail impact to the large wetland (Wetland 4) could not be reasonably avoided; as was the FHWA in making its finding that this project had no significant impact. Based on the fact that there are no practicable alternatives to the proposed trail as outlined above that meet the safety needs for this roadway, the city concluded that this project, with the trail proposed west of the road through the wetland was the least environmentally damaging alternative when considering factors other than just wetlands. TH 101 — Lyman Boulevard to Pioneer Trail (2011- 02756 -MTS) March 7, 2013 Storm Pond Alternatives Purpose: Provide the necessary stormwater treatment and storage for road runoff in compliance with City, watershed, and MPCA NPDES requirements. Background: There are generally three subwatershed divides within the project, as shown in Exhibit 2 (Drainage Map). As a result, collecting and treating stormwater generally requires three stormwater ponds, one in each subwatershed. Three ponds were designed near the wetlands in the lowest area of each subwatershed to treat water prior to discharging to the wetlands. Since the EA was published, wetland impacts were avoided through pond design modifications for Ponds 1 and 2, providing the storage and treatment required for the road runoff in those areas. In the southern subwatershed, however, the combination of topography, existing development and other regulatory requirements, do not allow avoidance of wetland impacts for Pond 3. Alternatives Analysis: East side pond option: The city has evaluated numerous options and held discussions with multiple landowners to locate the southern storm pond. Initially it was expected to be feasible outside the wetland, east of the road, as was described in the EA (Figure 4 of the EA). However, after residents east of 101 reviewed that document, they strongly objected to the east pond due to concerns with child safety and tree loss. In addition to safety concerns, the subject parcel was in foreclosure with the bank and there were concerns regarding the timely acquisition of the necessary easement. It was also pointed out that the pond location could impact the septic system design of that parcel, further complicating the potential to acquire space for a pond east of TH 101. Therefore, the city was forced to find an alternative pond location. No pond option: As an alternative to placing the pond in Wetland 5, the city asked the responsible wetland agencies whether it would be feasible to not treat the storm water before directing storm water to the wetland in order to avoid the physical (fill/excavation) impact to the wetland, given that the wetland quality was not high (monotypic reed canary grass). However, it was concluded that the watershed and wetland rules would not allow that option, and water quality was a greater concern than wetland fill given the wetland size, quality, and the presence of an impaired downstream water (Bluff Creek per MPCA). It was also noted by residents that the wetland already had flooding issues and therefore some runoff retention prior to discharging to the wetland was considered an important function that needed to be met by the treatment pond. West pond two -cello 1ii2n: The pond was shifted to the west side of the road to address public concern as part of the final EA and FONSI review with FHWA. In meetings with the responsible wetland agencies, we discussed the pond alternatives and alternate locations. Reconfiguring the pond to provide treatment outside the wetland but storage within the wetland (two - celled pond) was considered as shown in Exhibit 3 (2 -Cell Pond Figure). That configuration would have limited the fill in the wetland to 0.35 acres for berm construction, however, an additional 0.5 acres of wetland to the west would have been severed from the rest of the wetland and subjected to frequent water bounce. Therefore, the overall impact to the wetland was similar to the preferred alternative, however, the impact was deeper into the wetland basin, would have required greater easement area cost, and was expected to require additional wetland impact for maintenance access (not shown). The location of the wetland impact was considered, knowing that the quality of the wetland up to the first property line is low (frequently mowed and is primarily reed canary grass), and as you get further west into the basin it was less disturbed and wetter. Keeping the impacts closest to the road was considered the lesser of impacts between these alternatives. As such, this alternative pond configuration was not carried forward as it had greater overall project impacts. TH 101 —Lyman Boulevard to Pioneer Trail (2011- 02756 -MTS) March 7, 2013 West pond configuration options: Exhibit 4 (Pond 3 Design) shows the relationship of Pond 3 to the wetland and property lines. Moving Pond 3 further north of the proposed location to avoid much of the wetland would result in a significant impact to the property owner, to the extent that the entire property would have had to be acquired rather than just an easement. With the structures and improvements on this parcel and the adjacent parcel, the cost added to the project (more than $500,000) to acquire property would have made the project not feasible. Therefore, the option remaining was to minimize the amount of fill in the wetland resulting from the proposed pond. The pond shape, size and location was initially designed to minimize wetland impacts. With the road elevation currently being approximately 10 feet above the wetland, and the need to raise the roadbed another 3 to 4 feet as it approaches the Pioneer /TH 101 intersection (for safety and continuity reasons), the pond could not be shifted any closer to the road. Also, based on the storage volume and function needed from the pond, it could not be further narrowed to reduce wetland impacts. Conclusion: Therefore, the proposed location for the pond within the wetland was determined to be the least damaging environmental alternative after considering safety and engineering feasibility, functionality, other regulatory requirements, along with the wetland impacts. Lyman Blvd 64, _ i ,� w'•`- ��r •s $ +q tea. .� P "reserve Bandimere ' Park I - '• `" Future 40 - Ingle Family Lots t ;ll K a iF +�'>� �f ' S it ' `• \ Ra'Y ! • `' i i.: �'� i'r' , pr y7 �9. °w•. - tya a. a =- ♦ .♦ ,A , '� '� -g. .,vim. ; •,(— I f ",� '^ ` ri. • 96tist. 1, IT J I i` Y rF. ! ♦ i 1 %. Lry else♦ �'"r-N t'.i,= h♦ r'. C y? I I'd t �r I; 1 `xyy .- ; � , �„.. ♦ a _^ r ^ v�.l � � PioneerTra iit _.c \h 514 NORTH TH 101 From CSAH 18 to CSAH 14 o soo eoo °Fee` Exhibit 1 �Z. ­Jy "s 4M SCALE IN FEET - Ir All" TIN 101 Dminage A. as FIGURE NO. 1 I lu { �nr 5 i r i l GSAH t{ bnbBrT � j t k 7 -i"a 7 rt u I LymaniBlv6 Preserve Bandimere Park 4" Au KP- M t4 rill r j low W. A.'-z IN ;6 0 300 e o TH 101 From CSAH 18 to CSAH 14 �Feet Exhibit 1 TH 101 —Lyman Boulevard to Pioneer Trail (2011- 02756 -MTS) February 13, 2013 TH 101 Trail Alternatives As stated in the EA and concluded in the FONSI the trail on the east side of TH 101 is part of the Chanhassen Comprehensive Plan (Comp Plan), and the trail on the west side of TH 101 and tunnel are called for by the Metropolitan Council Regional Trail Plan. Pedestrian and bicycle safety are the primary reason for constructing a trail on both sides of the roadway. The city has identified in its Comp Plan the expansion of residential development in the current open space west of TH 101. The number of future trail users in the future that want to cross from west to east across TH 101could be significant once the residential development occurs, with up to 400 new residences being added west of TH 101. Given the curves and hills on this alignment, crossing the corridor by pedestrians at grade is not safe, even in the improved condition. The sight distance will be improved by flattening some of the curves and hills, however, curves and hills will remain. The corridor is also being widened from two lanes to four lanes, plus turn lanes at intersections. Therefore, the time to cross the roadway will double due to increased width. Safety concerns were the primary reasons why federal funding was approved for a tunnel underpass, to allow residents west of the road to safely access trails and parks east of the road. The trail is needed on the west side of the road to allow pedestrians access to the underpass. Other locations for the underpass were considered, however, due to grades and water table elevations, locations nearer to Wetland 4 were not feasible. Alternatives were considered to avoid the trail through Wetland 4 by routing users south to Pioneer Trail, to cross at the signalized intersection, then back north on the east side trail. This may avoid the 0.3 acres of trail impact to the wetland, however does nothing to improve pedestrian crossing safety, since the distance for this "detour" would add 0.5 miles to cross the road (quarter mile each direction). In reality, most people would not go an extra half -mile out of their way just to cross the road. Just last year a child on a bike was struck and killed by a car when attempting to cross a four -lane segment of TH101 to the north of this segment. Because the western trail is required for user safety, the trail impact area has been minimized by reducing the boulevard width, increasing side slopes adjacent to Wetland 4, and using the area temporarily impacted by road surcharge for the trail. Exhibit 1 shows the location of the proposed western trail and tunnel with respect to the future development, the Pioneer Trail Intersection, and 96h Street. Based on the above facts, the DNR was convinced that the trail impact to the wetland could not be reasonably avoided, as was the FHWA in making its fording that this project had no significant impact. Therefore, the city concluded that this project, with the trail proposed west of the road through the wetland was the least environmentally damaging alternative when considering factors other than just wetlands. Storm Pond Alternatives The city has evaluated numerous options and held discussions with multiple landowners to locate the southern storm pond. Initially it was expected to be feasible outside the wetland, east of the road, as was described in the EA. However, after residents east of 101 reviewed that document, they strongly objected to the east pond due to concerns with child safety and tree loss. In addition to safety concerns, the parcel was in foreclosure with the bank and there were concerns regarding the timely acquisition of the necessary easement. It was also pointed out that the pond location could impact the septic system of that TH 101 —Lyman Boulevard to Pioneer Trail (2011- 02756 -MTS) February 13, 2013 parcel, further complicating the potential to acquire space for a pond east of TH 101. Therefore, the city was forced to find another alternative pond location. The pond was shifted to the west side of the road to address public concern as part of the final EA and FONSI review with FHWA. As an alternative to placing the pond in Wetland 5, the city asked the responsible wetland agencies whether it would be feasible to not treat the storm water before directing storm water to the wetland in order to avoid the physical (fill/excavation) impact to the wetland, given that the wetland quality was not high (monotypic reed canary grass). However, it was concluded that the watershed and wetland rules would not allow that option, and water quality was a greater concern than wetland fill given the wetland size, quality, and the presence of an impaired downstream water (Bluff Creek per MPCA). It was also noted by residents that the wetland already had flooding issues and therefore some runoff retention prior to discharging to the wetland was considered an important function that needed to be met by the treatment pond. Moving Pond 3 farther north of the proposed location to avoid much of the wetland would result in a significant impact to the property owner, to the extent that the entire property would have had to be acquired. With the structures and improvements on this parcel and the adjacent parcel, the cost added to the project (more than $500,000) to acquire property would have made the project not feasible. Therefore, the option remaining was to minimize the amount of fill in the wetland resulting from the pond. In meetings with the responsible wetland agencies, we discussed the pond alternatives and alternate locations. Reconfiguring the pond to provide treatment outside the wetland but storage within the wetland were considered. That configuration would have limited the fill to 0.35 acres for berm construction, however, an additional 0.5 acres of wetland to the west would have been severed from the rest of the wetland and subjected to frequent water bounce. Therefore, the overall impact to the wetland was similar to the preferred alternative, but would also require greater easement area cost, and was expected to require additional wetland impact for maintenance access. Therefore, the proposed location for the pond within the wetland was determined to be the least damaging environmental alternative after considering safety and engineering feasibility, functionality, other regulatory requirements, along with the wetland impacts.