2023 - "Last Mile" Project - Overview
These are the Parcels that are involved in this project. (back to Work Projects Page)
Area is "most upstream" headwaters
Junction of Northmost and Eastmost fingers (Oct 22)
Last work done in 2022 on Northmost finger (Oct 22)
715 93rd Ave SE (Jan 22)
93rd Ave on south side of culvert (Jan 22)
93rd Ave on south side away from culvert (Jan 22)
93rd Ave on south side toward culvert (Jan 22)
1033 93rd Ave SE behind fence (Jan 22)
Allowable Ditch Profile of Ditch Dist. creation
Estimated Length of work - one mile
2-Ft Contour of 2023 Work Area
2-Ft Contour of northmost 2023 work area
North Hart Road SE culvert "dam"
2023 "Last Mile Project" - Maintenance
This work was done to re-establish the Hopkins Ditch in this "Last Mile".
Ditch needed to be re-established to deal with the additional 114 Acre Feet
of Stormwater being added to the top of the Hopkins Ditch by "The Preserve".
Preparation work
Forestry Mulcher
Near Hart Road SE
South area near first fork in Ditch
middle of south work area
Laser Level used to keep Ditch at correct elevation
50 yds from
Hart Rd SE
Hart Road culvert - TC Roads to replace
From Hart Road SE looking down-ditch
#2 from Hart Road SE
#3 from Hart Road SE
#4 from Hart Road SE
#5 from Hart Road SE
#6 from Hart Road SE - transition to peat bog area
#7 from Hart Road SE - top of peat bog area
#8 from Hart Road SE
#9 from Hart Road SE
#10 from Hart Road SE (looking north)
#11 from Hart Road SE - near fork
#12 from Hart Road SE - at fork
Equipment used - totally "in the dry"
Questions & Answers about this Project:
What needs to be done?
This one mile length of drainage needs the Ditch Profile established so that water can flow in a directed fashion and not just spread out over the area to drain.
Why was this Ditch not maintained prior to this?
Until now, the amount of stormwater being carried away by the Hopkins Drainage Ditch in this area has not caused major concerns, and the finances of the Ditch District have been focused on keeping the main channel of the Ditch clear. The "Hopkins Ditch Flood Report" dated 3/31/2023 details this information.
Why does this need to be done now?
Due to the recent buildout of 550 homes in The Preserve and the 2 associated Business developments a massive increase in the amount of stormwater flow has occurred that is expected to be carried away by the Hopkins Drainage Ditch. The "Addendum to the Hopkins Ditch Flood Report" explains this fully.
What exactly needs to be done?
In order to reestablish the Ditch, we need to:
FIRST - Determine exactly where the natural flow is/was and where the former ditch channel was.
- To do this we will need to do a "Drone LiDAR Survey" (Flown on 6/14/23 - Data Completed 7/14)
LiDAR Data
SECOND - Make the "ditch-line" determined by the LiDAR an "on-ground line"
Flagging Set by survey crew on 7/18
- Survey Shows Hart Road Culvert needs to be replaced and lowered
THIRD - Have the "ditch-line" cleared of brush and trees.
- Currently this is being delayed by Thurston County; Rep. Griffey is assisting; Hope to start by 8/24
FOURTH - Determine where Access will be made for the removal of the soil necessary to create the Ditch Channel.
- It is estimated that there will be 7763 Cubic Yards of soil that will need to be removed (approx. 650 Dump Truck loads)
- On site estimates have shown that less soil will need to be removed from site and that most can be safely moved to areas away from ditch to higher ground; talks with WDFW will need to confirm this.
FIFTH - Have the actual work done.
- Planning for end of August and into Sept.
Interesting fact: just north of 100th Ave SE is a Gravel area!
Without the Hopkins Drainage Ditch, the area in question would be yet another "bowl" in the Salmon Creek Drainage Basin that did not drain. The pictures below show that there had to be a deep channel dredged through this Gravel Washout in order for this area to drain at all.
HPA and SEPA:
What is a HPA and why is it needed?
An HPA is a WA Dept of Fish & Wildlife "Hydraulics Permit Approval". These "Permits" have always been used by the District when any work is done. Lately though, Thurston County has been pushing the WDFW to require SEPA (State Environmental Protection Agency) Permits. The Ditch District believes that we are Exempt from these requirements for Ditch Maintenance, however we are complying with this request. Below is a LINK to the "Environmental Checklist" and our "Determination of Non-Significance".
SEPA Checklist Link
Comments will be taken and evaluated through 8/14/2023.
Please email your comments and concerns to commissioners@HopkinsDrainageDitch.us
Determination of Non-Significance
This is typical Drainage Ditch Maintenance work. The re-establishment of the Ditch in this area is due to an increase of 114 Acre Feet of flow in the ditch during those stormwater flooding times and is vitally necessary due to this increase of water being introduced into the Ditch by the City of Tumwater.
Gravel washout area just north of 100th Ave SE.
We love to take pictures and show them to the world.
North side of Culvert at 100th (Oct 22)
Halfway through gravel washout (Oct 22)
From North end of Gravel washout looking south (Oct 22)
At north end of Gravel washout (Oct 22)
Looking up-ditch from N end of Gravel area (Oct 22)
Looking South from junction of North fingers (Oct 22)
Dec-23 "High Water" pictures (after almost 6" of rain)
Water came up fast, but also went down fairly fast.