Attch B Source Narrative Webb Slough Quarry.pdf

Oregon Department of Transportation Region 5 Geology 3012 Island Avenue

La Grande, OR 97850

(541) 963-1598; (541) 410-6693 cell

September 27, 2023

To: Paul Howland Assistant D12 Manager, Pendleton

Rich Lani District 12 Manager, Pendleton

From: Bobbi Jean Cummiskey Region 4/5 Engineering Geologist

Subject: Material Source Narrative D12 Chip Seal Rock Production Project 2023 Umatilla County

RE: Prospective Material Source Webb Slough Quarry ODOT Source #OR-30-027-5, DOGAMI #30-0097 Section 12, T. 3 S., R. 30.5 E., W.M.

US 395B (Hwy 028), M.P. 34.55

This narrative memo and all of the attachments (exploration air track drill hole logs, laboratory testing data, and the DOGAMI Operating Permit), should be duplicated and distributed to all bidders that inquire about this prospective material source, according to Section 00120.25 of the 2024 Standard Specifications for Highway Construction. This is an existing ODOT-owned material source.

ODOT Region 5 is offering this prospective material source for production of crushed aggregate for chip seal work in 2024 on Highway US 395B (Hwy# 028), and if proposed by the Contractor, the aggregate needed for Highway OR 37. The development plan for this source is based upon estimated project material requirements of 4,400 cubic yards (cyds) of material. The quarry development plan sheets identify an excavation area and associated volume adequate to supply the aggregate materials necessary to complete the project.

The Webb Slough Quarry is located in the Blue Mountains physiographic province of northeastern Oregon. This area is shown on published geologic maps as within the mapped Grande Ronde Basalt (symbol Tcg), part of the Columbia River Basalt Group, erupted predominantly during the Miocene geologic epoch (Geologic Map of Oregon, 1991, 1:500,000, compiled by G.W. Walker and N. S. MacLeod).

Attachment B - Source Narrative Webb Slough Quarry

Webb Slough Quarry D12 Chip Seal Rock Production Project 2023 Page | 2

Aggregate from the Webb Slough Quarry has been used on an intermittent basis for various County and State roadway projects since the site was acquired in 1928 and expanded in 1943, and was last used in 2009 for the Emergency US 395 Battle Mountain Landslide Repair at MP 37.28B where approximately 20,000 cyds of stone embankment material was produced. Drill holes for the explosives for a rock production in 2005 encountered ground water in the northwest area, along with some of the exploratory air track holes along the western boundary drilled on April 1, 2003 (see Air Track Drill Logs AT03-54 – AT03-61 and Exploration Map). Information concerning the operational history in this source is limited. Some information is available for review in the Region 5 Geology office in La Grande. Any contractor interested in looking at available information not provided here should call and schedule a time to review the material.

Someone from the Geology staff must be present when the information is being reviewed to maintain accuracy and consistency in distribution of information.

The development concept for this entry is to lower the quarry floor of the existing quarry to a common elevation, and to expand the quarry to the south, to provide an area for processing and stockpiling for future entries into the 20 acres addition to the south. Rejects will be utilized to form berms between the existing quarry and the highway for visual and sound screening. Access roads will be constructed to elevations of the new working floors and to the top of the working faces for equipment access.

The general development plan for this quarry is to have future entries continue mining to the south into the quarry addition property until reaching property limits or the resource limits, in order to maximize the use of the resource and generate additional floor space for processing and stockpiling. Overburden from each operation will be utilized to construct safety berm(s), with the excess salvaged and stabilized for reclamation purposes according to the development plan map and specifications.

In conformance with the 2024 Standard Specifications for Highway Construction, subsection

00120.15 Examination of Work Site and Bidding Documents, Contractors should make an on-site visit to this source to familiarize themselves with the existing conditions and appearance of the source and to visually inspect the existing quarry faces and the surrounding ground surface in advance of bid preparation. Based on the on-site visit and review of all available information, Contractors will then be able to use their best judgment to prepare a bid based upon existing site conditions, the conditions they expect to encounter at the time of the proposed operation, and on the most accurate information available for the source. Documentation contained within this material source narrative packet is for informational purposes only; they are not meant to replace those pages supplied in the Project Bid Packet.

Attachments:

DOGAMI Permit Laboratory Data Drill Hole Logs