Let's start with an anecdote about a call to SSTL this past summer.
Home Owner (HO): I have a problem with my western red cedar. Its turning brown. Its really important to us, as its the focal point of the yard. Its about 25" around it, and 25' tall.
SSTL: Okay, is the brown foliage predominantly the inner foliage with the rest of the foliage remaining green? Cedar have seasonal "flagging" where the older, less sun-exposed, less productive foliage has compounds pulled out of them back into the branches and trunk, like deciduous leaves in the fall, turning them brown. The winter winds will blow the brown "flagged" foliage out of the tree, and they will look great in the spring. Its a normal thing for western red cedars.
HO: No. The foliage is turning brown all over it.
SSTL: Has there been any construction or excavation in the area recently, say over the past five years. Trees' health often declines or improves slowly over the course of a several years.
HO: Well, we had a new septic system installed near the tree.
SSTL: Has there been a grade change? Have they changed the soil level?
HO: Well, yes. They added about two feet of dirt around the tree, but they didn't get that close to it with the excavator so I don't think that they damaged the roots.They couldn't have gotten closer than four or five feet of the trunk.
SSTL: Well, basically what you are telling me is, first, they damaged some of the roots by digging. Second, they compacted the soil tremendously by driving a 30,000 pound machine all over the roots. Third, they buried the trunk and suffocated the roots, which are normally in the upper 24" of the soil by burying them under two feet of soil, which was compacted in the process. Now you're seeing the foliage browning all over the tree and wondering what you can do about it. I'm sorry, but your tree is probably going to completely die. Its likely to late to do anything but learn from the experience. Next time you're going to have construction performed, please call first, allowing up to come up with a Construction Protection Plan to save the trees that can be saved, and removing the trees that won't make it, while its easier and cheaper.