Comments/Follow-up Items

During and following the presentation, a question and answer session was conducted. The responding agency or group is noted in parentheses after the response. The following comments/responses were received.

1. Where will the location of the 6th Avenue pond be? Response or Follow-up Identified:
   The pond will be located near the existing southbound on-ramp from 6th Avenue in the infield area. The pond can be easily maintained at this location (Muller/FHU).
2. Where is the Santa Fe/Alameda pond? Response or Follow-up Identified:
   The pond will be located in the right of way area at the southwest corner of I-25 and Alameda. (Muller/FHU)
3. What will become of the stormwater discharge from the area on 6th Avenue just west of I-25 where there are no stormwater treatment ponds? Response or Follow-up Identified:
   The stormwater will discharge directly into the South Platte River. This location near 6th Avenue is a relatively small area and is constrained by highway structures and drainages such that a stormwater treatment system is not feasible. To compensate, CDOT does best management practices along 6th Avenue such as using less salt and sand on highway and conducting street sweeping.
4. Does the area (Northeast quadrant of 6th interchange) have room for a potential City and County of Denver (CCD) pond? Response or Follow-up Identified:
   Yes, there is enough area for the CCD to create a stormwater treatment system. This area is within the CDOT right of way, and special permission and coordination will be needed between CDOT and CCD (FHU).
5. What will the east/west bike/pedestrian bridge look like specifically at Alameda? Response or Follow-up Identified:
   The east/west bike/pedestrian bridge is located at Bayaud. The bridge would cross Santa Fe/Kalamath, the Consolidated Mainline railroad tracks, and the I-25. The design of the bridge has not been completed. (FHU)
6. What would be the width of the trail? Response or Follow-up Identified:
   The trail width has not been determined at this time (FHU).
7. Will new stormwater treatment structures create additional issues that need to be addressed? Response or Follow-up Identified:
   Yes. The outfalls from the treatment ponds will be designed for functionality and aesthetics. Discharges from outfalls during or immediately after storm events may impact existing wetlands and some wetland mitigation will be needed (FHU)
8. Do different alternatives have different BMP alternatives? Response or Follow-up Identified:
   Yes, there are different drainage scenarios for each alternative. One alternative addresses the interception of groundwater that may be potentially contaminated. Special treatment and discharge permits from the Colorado Department of Public Health and Environment (CDPHE) would be needed. (FHU)
9. Can sections of alternatives be interchanged? Response or Follow-up Identified:
   Yes, alternatives are based on specific parameters. The preferred alternatives will be a composite scenario to best fit the need of the project. (FHU)
10. Is there adequate shoulder space on the Valley Highway? Response or Follow-up Identified:
    Today on the Broadway viaduct there is no shoulder. Along I-25, the existing conditions have a 2 foot (ft) inside shoulder and the outside shoulder is 6 to 9 ft. The proposed I-25 will have 12 ft shoulders, which are more standard for safety. (FHU)
11. Will these 12 ft shoulders eventually become lanes? Response or Follow-up Identified:
    At this point, there is no plan to make those lanes. (FHU)
12. Does TREX have 12 ft shoulders? Response or Follow-up Identified:
    Unsure potentially not in the Narrows section of T-REX. (FHU/CDOT)
13. Will the next bike/pedestrian crossing be at Mississippi? Response or Follow-up Identified:
    Alameda will still have the bike/pedestrian component. Cherokee Development (Gates Area) is looking at having a crossing. Another will be at Mississippi. (FHU)
14. Is there an opportunity to put a pond west of the South Platte River on the General Chemical property? Response or Follow-up Identified:
    There are problems with this approach. First, much of the land near General Chemical is contaminated and would cause an environmental risk if disturbed. This property is under-going remediation through the CDPHE under a Voluntary Clean Up Program. Second, the drainage coming from I-25 would be on the eastern side of the South Platte River and a conveyance system would have to be constructed over the river. (Muller)
15. What is the coordination between this project and CCD? Response or Follow-up Identified:
    We have been working closely together to ensure the drainage plans to do not conflict and we are able to plan ahead. Both agencies are working toward managing stormwater, improving drainage and improving the water quality of the South Platte River. (FHU/CCD)
16. Will you look at conceptual designs of ponds? Response or Follow-up Identified:
    Yes, conceptual designs will be in a technical reference document entitled Water Resource and also mentioned in the Draft EIS. (FHU)
17. What about the 8% of the stormwater that is not included in a BMP? Response or Follow-up Identified:
    Of the entire drainage area of the I-25 Valley Highway Project, only 8% of the area that would receive and collect stormwater is not captured for treatment. The areas include the southwest portion of I-25 and 6th Avenue and portions of the far south side of the Broadway area. This is a high percentage of capture. The Valley Highway will also collect and treat stormwater coming from the CCD drainage area.
18. Can water quality improvements be quantified? Response or Follow-up Identified:
    Water quality improvements could be estimated based on a costly and time intensive water quality monitoring program once BMP’s are installed. Significant background data would need to be collected. Quantification of water quality improvements would be difficult because the South Platte River is a dynamic system with a variety of point and non-point sources other than the highway. Currently, all stormwater received and collected within the I-25 area are directly discharged into the South Platte River. Intuitively, water quality of the South Platte River will be improved from the Valley Highway EIS by constructing and maintaining stormwater ponds that will be used for stormwater treatment. (FHU/CDOT).
19. How are the ponds designed? Response or Follow-up Identified:
    The pond is designed to contain a 2 year storm event according to criteria established by CDOT and the Urban Drainage and Flood Control District. The pond is designed specifically for easy maintenance and proper volume retention. (Muller)
20. Does project allow for wildlife? Response or Follow-up Identified:
    Some enhancements will allow for wildlife, but the primary focus is to avoid impacts to the South Platte River. (FHU)