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Home My WebLink AboutInquirey RE ERC Rail Removal Ph 1 Stormwater RequirementsTri, Thanks for your inquiry. After reviewing your information, it is the opinion of the Regulations and Planning Unit of Stormwater Services Section that the described activity of removing rails and ties and resurfacing with a soft surface over the existing rail ballast would not require formal drainage review as described in the King County Surface Water Design Manual as the project meets the intent of the “maintenance” definition; and does not fall into one of the categories of pavement maintenance that are not categorically exempted from drainage review. This interpretation is based on the following: The existing / current use of the project corridor is for walking/biking. The project activities can be considered as repair or replacement of a non -functioning facility or structure as the rails/ties are antithetical to walking/biking as well as a safety hazard. The project activity does not create a significant hydrologic impact. The project will not concentrate currently dispersed runoff. The net result of removing impervious trail ties and timbers and the addition of a soft surface walking / biking trail gravel should be a surface with similar hydraulic response as the existing trail (e.g. railroad ballast with trails/timbers in place). Further, the project activities are not one of the listed pavement maintenance practices within the definition of maintenance that are not categorically exempt form drainage review. The existing railroad ballast is the “base course” and is not being removed to bare soil, therefore this activity is not considered replaced impervious surface. The existing railroad ballast is considered an impervious surface and therefore , as long as the trail/footprint is not widened , adding a soft surface over the existing footprint is not creation of new impervious surface( this addresses part 1 of sentence 1 in definition of new impervious surface). Lastly, the proposed activity also does not constitute, “addition of a more compacted surface, like paving over pre- existing dirt or gravel…” given that the net result of removing impervious trail ties and timbers and the addition of the proposed soft surface walking / biking trail gravel should be a surface with similar hydraulic response as the existing trail (e.g. railroad ballast with trails/timbers in place). Please let me know if any of the information that this interpretation is based upon changes or is incorrect as this may require a re-evaluation. This information includes but is not limited to: existing and proposed trail material types, the assumption regarding keeping existing unconcentrated flows unconcentrated; and the assertion of no expansion of the trail footprint. Please let me know if you have any questions or concerns. Thanks Mark Mark Wilgus, P.E. Engineer IV, Stormwater Services Section PH: 206-477-4848 From: Ong, Tri Sent: Monday, August 29, 2016 4:05 PM To: Wilgus, Mark Cc: Kameda, Wesley; Jacobs, Erica Subject: ERC Rail Removal Ph. 1: Stormwater Hi Mark, From our conversation last Thursday, below are justifications that this project falls under the category for maintenance and is exempt from drainage review. KC Parks will need to obtain grading permits from three local jurisdictions (Bellevue, KC DPER, and Renton). Based on the 2016 KCSWDM: · This project falls under the definition “maintenance” since the ERC current use is a regional trail and the rail removal is an activity taken to prevent a decline, lapse, or cessation in the use of currently serviceable structure…. The existing drainage pattern remains the same and there is no significant hydrologic impacts. Furthermore this maintenance project is exempt from drainage review since there is zero new or replaced impervious surfaces. cid:image001.jpg@01D203AB.701EBFC0 · This project generates zero replaced impervious surface since removal of the rail and timber ties are within the existing railroad ballast and not down to bare soil or below the foundation of the railroad ballast. See definition below…. cid:image002.jpg@01D203AB.701EBFC0 · This project generates zero new impervious surface. The removal of railroad steel and timber ties reduces the amount of impervious surfaces by installing an ADA gravel surface that is similar in hydrologic characteristic to the railroad ballast. cid:image003.jpg@01D203AB.701EBFC0 cid:image004.jpg@01D203AB.701EBFC0 Project Description: King County proposes to remove railroad track (rails and timber ties) from the Eastside Rail Corridor (ERC) and restore the railbed with 4-inches of ADA crushed gravel material on top of the railroad ballast suitable for maintenance access and safe for use by pedestrian and wide tired bicycles. The gravel surface would be graded and would be no greater than 10 feet wide, matching the existing railbed ballast cross section with a cross slope of less than 2%. Removal of the rail infrastructure will improve access, efficiency and safety for maintenance and operations in the corridor. The project limits is from 108th Ave NE in Bellevue (at Kirkland boundary) to the southern limit of the County’s ownership in Renton at MP 5.0 which is adjacent to the north end of Gene Coulon Park. Since acquiring portions of the corridor in 2013, the Parks Division has worked to clear invasive and hazardous vegetation, illegal dumping, encroachment, clean culverts, and address graffiti problems. However, the rails and ties in place along the County-controlled segments of the rail banked ERC prevent Parks’ regular and heavy maintenance equipment from accessing all areas of the corridor. The ERC is a former freight rail corridor formerly owned by BNSF and currently owned and maintained by King County. The County is planning to install a paved regional trail in the corridor in the future. For now the existing rails and ties are in still in place but no longer in use by any freight operation, the corridor has been rail banked for interim trail use under the National Trails System Act (Rails to Trails). Removal of the railroad infrastructure will create a safe soft surface interim trail condition in the corridor for pedestrians and wide tired bicycles. The project will also include appropriate signage at crossings, placement of removable bollards and boulders at crossings, installation of fencing for fall protection in the vicinity of steep slopes, and installation of low split rail fencing along sensitive areas (wetlands) to prevent encroachment. Where feasible, trestles will have an interim walkable decking surface and railings installed. No work will occur in wetlands, streams or sensitive areas. Thanks, Tri Ong, P.E. s Capital Project Manager III s King County Parks and Recreation Division s 206.477.3591 s cell 206.491-6037 s Tri.Ong@kingcounty.gov <mailto:Tri.Ong@kingcounty.gov> www.kingcounty.gov/parks <http://www.kingcounty.gov/parks> | Facebook <http://www.facebook.com/home.php?#!/pages/Seattle-WA/King-County-Parks- Your-Big-Backyard/18326133930?__a=10&ajaxpipe=1> | Blog <http://kingcountyparks.wordpress.com/> 200 parks s 175 miles of trails s 26,000 acres of open space