Humboldt County board advances engineering work on DD 11 Sub 1 drainage improvement, schedules preclassification and continued hearing

Colin Klingbile, the project engineer, told the Humboldt County Board of Supervisors at a public improvement hearing that a deteriorating clay tile system in the DD 11 Sub 1 area needs substantial work and that an amended engineering report proposes abandoning some shallow, broken clay tile and installing new pipe deeper and in larger sizes.

Klingbile said the amendment drops the original plan to remove and crush the existing clay tile along a portion of the alignment and instead recommends abandoning that old tile so future pattern tilling of the farmland will not interfere with installation. "In the northwest corner of Section 8... those are 40 acre parcels," Klingbile said, describing the area and explaining why the project design was amended. He said the amendment would also avoid running the new pipe in the exact trench of the old tile where agricultural operations would make installation difficult.

The engineer described a proposed system of roughly 7,000 feet of new pipe including a short section of 42-inch pipe to carry water under County highway C26, transitions to 36-inch and 30-inch reaches, and a 24-inch stretch near a large depression by 180th Street. Klingbile said the conceptual estimate for the project, using reinforced concrete pipe (RCP), is $787,000.

Klingbile laid out two material options: reinforced concrete pipe and dual-wall high-density polyethylene (HDPE). He said RCP is more expensive on a materials basis but is structurally self-supporting, while success with plastic pipe is highly dependent on installation quality, bedding and inspection. "If the board and the landowners are interested in bidding both ways, that's something I'm open to doing," Klingbile said. He recommended at minimum a drainage coefficient of a half-inch per day and offered that the district could consider a one-inch-per-day design to increase long-term capacity.

Landowners and board members pressed on several practical points: whether the private 18-inch tile in the northeast corner would remain in use (Klingbile said tenant investigation suggested it likely would), how to classify lands that currently drain to private tile, and how annexation into the district later would affect cost shares. Several speakers noted it would be reasonable to give lands that already have private tile a reduced assessment but to keep them in the district rather than allow future free hookups without payment.

After discussion the board voted to direct the engineer to prepare plans and specifications that include: RCP and HDPE bid options, designs for both a half-inch and a one-inch drainage coefficient, and a preclassification of benefits based on the engineer's estimate. The board also set a follow-up schedule: the engineer was asked to provide preclassification estimates within about two weeks, and the board continued the public hearing and reclassification process to Aug. 4, 2025, at 9 a.m.

Board members and landowners said they preferred having both material options bid and said they wanted the district to "do it right" rather than underbuild a system that will require frequent repairs. One landowner urged the board to consider the larger drainage coefficient if the incremental cost was modest: "If you're gonna do it, you might as well do it the right way," a landowner said.

The board's direction will lead to formal plans and advertised bids; Klingbile said he would include the option bids and expected to deliver the requested preclassification and plans in the timeline set by the board.

Provenance: The improvement hearing opened at the board meeting and the engineer's presentation began at the transcript section where Colin Klingbile introduced himself as the project engineer and described the amendment to the engineer's report. The board later made the motion to require plans, bid options, preclassification and to continue the hearing to Aug. 4, 2025.