DC held the Klingle Trail Open House Wednesday night and what I saw was encouraging. David Alpert covers some parts (lighting, stairs to Connecticut, and the width - 8ft, 10ft or 12 ft) at his blog. I suspect 10 feet is what we'll get.
The two most encouraging parts were that they weren't limiting themselves to water permeable surfaces for the 0.7 mile trail and they had a good plan to connect to Rock Creek Park Trail.
The trail will include a pretty steep climb from Rock Creek to Woodley Road - in some places as steep as 9.5% grade, so a crushed stone surface just won't cut it in those places. If a non-permeable surface is deemed acceptable, DC has plans for bioretention ponds and storm water management that will mitigate the trail surface. The road washed out because a culvert carrying Klingle Creek under the road filled with silt. DC (and it is a combined effort of several agencies) is considering either replacing the culvert with a better one, building the bioretention ponds or finding another way to move the water across the trail without washing it out.
As for the Rock Creek Park Trail connection, the plan as presented is to take about 10-12 feet of the 24 foot wide eastbound Klingle Road - the underpass that connects to Beach Drive - and turn it in to a bike path that connects the Klingle Trail to Rock Creek Park Trail. You can see it on the right hand side of this image where it is marked as "Connection to Rock Creek Trail". The underpass serves 12 houses on the west side of Porter and north of Klingle Road, so a single 12 foot wide lane should be sufficient to meet their needs.
The entire Klingle Road/Porter Road interchange could be redesigned considering the limited use of the area and a down scaled interchange could more than mitigate the impact the trail. That is outside the scope of this project, but that shouldn't stop people from commenting to that effect.
At the next meeting this spring, they'll present the EA and the alternatives.