Friday, July 27, 2018

Forest Practice and a Deep-seated Glacial Landslide

I reviewed a recent forest practice application at Tala Point in Jefferson County. The initial application map is shown below: 

Red outlines the proposed harvest area.
Trees are left within the semi circular area due to a nest site. 

Based on my geology assessment, I noted that the proposed harvest included areas on the northwest portion of the harvest that are within the groundwater recharge area of a landslide prone area. 

Jefferson County GIS based map of landslide hazards
The slide hazard map is based on mapping by Hansen (1976)

These slide areas are deep-seated slides in that the failure zones are deeper than the tree rooting depths. The slides are in glacial related sediment and thus under forest practice rules should be considered glacial deep-seated landslide areas. The forest practice rules call for the groundwater recharge area to glacial deep-seated landslides to be either avoided or follow a much more detailed application review process. Typically, when what are termed rule identified landforms are recognized, they are not harvested. 

Our report was forwarded to the DNR (Department of Natural Resources) as a public comment on the proposed harvest on July 2. On July 16, the DNR issued the following notice:  

Dear Interested Party,

Thank you all for your comments and phone calls regarding Pope Resources’ harvest proposal under Forest Practice Application/Notification (FPA/N) number 2615518, commonly referred to as Tala Point.  I wanted to take this time to provide an important update on the processing of this application.

After initial remote review of this application and a subsequent July 6th field review of the western half of this proposal with our staff geologist, it was determined that this proposal contains, or is adjacent to, rule defined potentially unstable slope features as described in WAC 222-16-50(1)(d).  As a result we have requested additional information from the landowner in the form of a report from a qualified expert.

As of this morning, the applicant has chosen to withdraw FPA/N 2615518.  Please feel free to share this information with other interested individuals or those I may have inadvertently missed.

Thank you again for your interest in this application,

A new application was submitted July 24. This new application pulled the harvest boundary back away from the slides and excluded the groundwater recharge area. 

The system worked and the timber company and the DNR followed the forest practice rules.  It was good to see geology agreement between the comment, DNR and the applicant as to the landform, type of slide and the recharge are to the slide. 


Geoff said...

Yes, the system worked. Good work! Did you make any reference in your "public comment" that this was the "best available science?"

Dan McShane said...

I did not use that phrase, but did provide what could be termed best available science specific to the site in question. It is never clear in these cases if the comment report has any influence as the DNR does not typically directly reference the comments. Regardless, I am glad they took a closer look at that location.