Lime Ridge features 10 miles of hiking trails near Concord, CA.
from 680 take ygnacio valley road to concord. when you stop seeing houses and start driving up a big hill, that is lime ridge. there is parking at the first stop light once you get up and over the hill. park there at the gate and there is a map posted at the sign.
http://www.tripleblaze.com/trail.php?c=3&i=714