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Home My WebLink About20090136 Ver 1_More Info Received_20090306 Date: March 6,2009 "':;) <~,>~;~~\ , \~".~,~ V(('''';~ _ _ _ . __' """"J. .~I....~~ - ,", /' '~-""" E N GIN E E R S . P LAN N E R 5 . S C I E N TIS T 5 . CON ST R 1.) C T I O';,1ti,l~~ N'~E R s~~;;::>~ Landmark Center 11, Sune 220.4601 Six Forks Road. Raleigh, NC 27609. Phone 919,783,9214 . f'~.~9'783'9266 '/"":: ;'?>'~~ 6" \,.- ," - '-~;~t1~) \~?o ','~~;(,:_,-.~.~~) '~\;~:j - ~:;- '-t~ <'(} ~. '-:5- ASSOCIATES of NC Company: Job Number 12082306A Contact: Division of Water Quality 401 Oversight/Express Review Permitting Unit 1650 Mail Service Center Raleigh, NC 27699-1650 Cyndi Karoly, Supervisor Project: Dunn Creek Greenway DWQ Project # 09-0136 Wake County Subject: Review Comments Number of Items Description 5 Letter Response to Additional Information Requested by DWQ 401 Oversight dat~d February 25,2009. ,_ - ~----~- ------..--....-,--.--- -- _~_._"m -_...>>_._~-_.~,..~~_._---------_.__.~-~_.._,-_._~._--._---- D In accordance with your request D For your review IZI For processing D Plans reviewed and accepted D Plans reviewed and accepted as noted o For revision by you D For your use/files D Please call when ready IZI Please return to this office IZI Approval requested D Conference requested at your convenience Comments: I appreciated your advance email advising me of your need for additional information. If you have any questions, please contact me by email or at the following phone numbers office 919-278-2517 or by cell (919) 210-5481. Thanks, Steven if~ r. r;/kk- teven F. Stokes, LSS Environmental Scientist cc: Susan Simpson, Director Wake Forest Parks and Recreation Files It'({dill,~ {/1I(11I,~1i 1:\( ,'111'11((' www_r.., I_COM Town of Wake Forest North Carolina ....:. -~ i:). A '6.~ l~-~ .:.~ ' .(:) ~ en ~ ....~.,~} '2'", If. 1:~;. ~/'" .:*'./- c~ <1, q.. //<9 1;.~:i'7,~ <I' \~\.:". "l-'~"'j \ /' (~'-l .~/;;, -~l '(,\.,:. "r 'Y"' "'-". -c:;?,;, ...........- .>. .' , ""<i.').\ \y... . /~:f~ ) '- :.~- cf' -. \;0 ........'"") ~O March 6, 2009 NCDENR Division of Water Quality 401 OversightlExpress Review Permitting Unit 1650 Mail Service Center Raleigh, NC 27699-1650 RE: Review Comments for Dunn Creek Greenway, Wake Forest, NC UT to Smith Creek [030402, 27-23-(2), C, NSW] DWQ Project # 09-0136, Wake County Dear Ms. Karoly: We have reviewed the request for additional information received from the NCDENR Division of Water Quality dated February 25, 2009 and have prepared the following responses to your comments. Impact Justification (Avoidance and Minimization) We believe the request to reduce the width of the trail to 8 feet does not fit the use and purpose of the proposed greenway system. In our previous discussions with the DWQ, we talked about how this section of trail would be 10-feet wide while not having an adverse impact on the stream buffers. The DWQ letter suggests that by reducing the width to 8 feet there would be a significant reduction in the amount of impervious surface constructed in the riparian buffers, however this is not the case. We have calculated the net reduction area to be only 2301.08 sq. ft. or 1.7% of the entire buffer area. We believe the lO-foot width is necessary for the following reasons: 1) The proposed greenway is lO-feet wide in accordance with the NCDENR State Recreational Trails Grant obtained by the Town of Wake Forest, 2) provides access for emergency and maintenance vehicles, 3) allows safe passage distance for the anticipated volume of walkers, children, pets, joggers, cyclists, and roller bladders, 4) provides adequate sight distance at bridge sections, and 5) matches the existing section of greenway already constructed. Safe access for emergency and maintenance vehicles on the trail is essential. Since the greenway will be used by the City of Raleigh to maintain the existing sanitary sewer, the trail must be 10- 40] Elm Avenue' Wake Forest, NC 27587-2932 Phone: (9] 9) 554-6100' Fax: (919) 554-6195 . www,wakeforestnc.gov feet wide. The City of Raleigh has advocated successfully for a 10-foot minimum width for other trail sections and has stated that an 8-foot pavement width does not provide adequate width to avoid damage to the edge of pavement. In certain situations, the narrower width does not provide adequate sight distance for pedestrians to avoid service vehicles. More importantly, the paved section must be of sufficient width to accommodate emergency vehicles. For this section of trail, the paved path is the only route for emergency vehicles to reach someone on the trail needing medical attention. A 10- foot trail width would also provide safe passage for people traveling in both directions on the trail. Due to the location of the trail through a major subdivision, the Town of Wake Forest's Parks and Recreation staff project that a significant number of residents will use this trail. Local residents will use the trail not only for recreation, but also to access a major shopping development within walking distance. A wider trail will ensure that there is enough space to safely accommodate all users at peak times. A trail of 10-feet wide also is necessary to comply with the DWQ crossing guidelines while maintaining safe transitions at bends in the trail. DWQ requires that bridge crossings of stream and creeks be as close to perpendicular as possible; these perpendicular crossings result in sharp turns as the trail approaches three of the four proposed bridges on this route. At these sharp turns in the trail, a lO-foot wide trail will provide better sight distance so people can recognize oncoming cyclists and skaters more quickly. It is also important to people using the greenway trails that the trail width remain the same in between major features such a road crossings where users will enter and exit portions of the trail with no other access. The existing greenway trail from Rogers Road to the soccer fields was designed and approved to be to-feet wide. The existing pedestrian culvert provided at the new NC Hwy 98 Bypass was also designed and built as a 10-foot wide crossing under the highway. This is especially important for walkers with strollers who will enter this section from either the north or south end and who will appreciate a 10-foot trail to avoid bicycles and other pedestrians. In specifying a 10-foot wide greenway system, the Town of Wake Forest adheres to the design recommendation from a number of publications that provide guidance for greenway projects, including the American Association of State Highway Transportation Officials (ASSTHO), the North Carolina Department of Transportation (NCDOT), the Federal Highway Administration (FHA), and the Guide of the Development of Bicycle Facilities. Diffuse Flow The requirement for diffuse flow within the Neuse Buffer Zones applies to features that concentrate flows from drainage sources outside the 50-foot buffer zone that must then be distributed via a level spreader or similar device. There are no areas along this trail where a diffuse flow device is needed. The proposed trail does not require any new culverts to be constructed, any existing culverts to be extended, or any drainage pipe, collector ditches or channels to be installed that would concentrate stormwater flows. The proposed design avoids the need for diffuse flow devices by: 1) minimizing the amount of trail (impervious surface) constructed within the buffer zone, 2) installing no piped drainage, 3) crossing the existing drainage channel with long bridge sections to avoid construction in the 30- foot Zone 1 buffer immediately adjacent to the channel, and 4) avoiding existing discharge points from the adjacent subdivisions through the use of slightly elevated boardwalks. A look at the proposed greenway route shows where the trail was shifted away from the 30-foot sanitary sewer easement/dedicated greenway easement and moved away from the stream buffer. We have included two sections of boardwalk to avoid an existing wet area and to allow stormwater flows to travel through the natural buffer without channelization. We believe the design of the Dunn Creek Greenway has avoided unnecessary impacts to the Neuse River Buffer, has maintained a significant percentage of undisturbed buffer area, and has avoided the construction of any new drainage features near or within the existing creek. If you have any questions or need additional information, please let us know. Sincerely, ~ Susan Simpson, Director Wake Forest Parks and Recreation Cc: David M. Koss, PE, LEED@AP Chief Engineer Steven F. Stokes, LSS Environmental Scientist