Saturday, March 28, 2009

Wetland delineation and identification

For those of you who don't live in the Seattle area, be aware that King County imposes a pretty high degree of regulatory requirements on anyone who wants to build a home. These requirements sound great in the abstract, ie for protecting the environment on the other guy's property, but can be frustrating when you're the one dealing with it. I am just venting because there is nothing really you can do about, gotta live by the king's rules.

We started the first step last summer, by hiring a wetlands consultant (Altmann Oliver Associates) to mark the location and type of wetlands present on the property. John Altmann did a great job in my uninformed opinion; it was late summer time, and the vegetation was thick, but despite this he was quickly able to map the edges of the various wetlands. First he did a rough survey just to get an idea of what we were looking at. This is what the rough sketch looked like:

(The red line and circle was from me taking an initial crack at possible driveway and home locations...)

After that, John went back out to do the precise flagging of the wetland boundaries. I went with him on one of his trips; it was quite interesting but the guy sure knows how to move fast through brush; he really ran me ragged out there! Watching him work, it seemed like more of an art than a science; he showed me some tricks, like looking for certain types of vegetations (ferns are a clear-cut sign of moist or wets soil, I learned), or dark patches of soil, or using an augur to take a short core sample. We ended up with ~110 flagged locations, and a determination of the wetland types. (If you are interested, the official state manual for wetland determination can be found here.)

Next step was to hire a surveyor to map the exact location of the wetlands. We chose GeoDatum and arranged the work via email; a few weeks later, we had the survey done. A nice side-benefit was that the surveyors hacked some lanes into the brush to be able to reach the interior of the property; this made it easy for us to get in there as well.

Here is a screen capture of the Autocad file delivered by the survey company:

You can see that John and the survey company did actually have to go onto the properties to the north and south of us, in order to get an accurate representation of the wetlands...sorry guys!

After the survey was done, it was back to John to prepare the Critical Areas Ordinance pkg submission. This was the formal application to the county asking them to certify the precise wetland areas and types, as determined by John. Getting this certification is required before you can develop your property. It took a few weeks of waiting, but eventually the county mailed a letter saying they agreed with the submission, and we could go ahead and record the wetlands on the property title (the results are considered valid for five years).

I've described it in a few short words here, but this whole process required several months and quite a bit of money. Once you have the final wetlands delineation certified, this tells you roughly where you can or cannot build your house. Although the western fifth of our lot was classified as essentially a solid wetland and there was another large wetland in the northeastern corner, there was plenty of room in the middle of the property for our needs, and a reasonable path for a driveway coming in from the eastern property line.

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