ND NP THRO 204 Buck Hill Road Pavement Memo

Memorandum
Subject: ND NP THRO 204(1)
Buck Hill Road
Existing Structural Section Thickness
Investigation and Pavement Memo

Date: November 15, 2024

From: Ron Andresen
Materials Engineer
To: Ryan Olson, PM
Wilmari Valentin Medina, Designer
Introduction:
Buck Hill Road, also known as Route 204, is in the Southeast portion of the South Unit of Theodore Roosevelt National Park. The route begins at the intersection of Buck Hill Road and the South Unit Loop Road. The route then proceeds southeasterly for approximately ¾ of a mile and ascends approximately 300 feet vertically to the Buck Hill Overlook parking area. This project proposes to rehabilitate the existing pavement and address subsurface issues observed along the route, including a previously identified landslide area. The project further proposes to reconstruct and expand the Buck Hill Overlook parking area at the end of the route. This memorandum provides a summary of the existing roadway thickness. The project was drilled by Dom Monarco on March 7, 2024.

Findings:
Five holes were made in the roadway. The depth of each hole was approximately five feet. The table below shows the specific hole information.

Hole Information

Hole
Number

Location

Existing Asphalt
Thickness (in)

Hole #P1

Station 102+00,
left

3.0

Hole #P2

Station 108+10,
left

3.0

Hole #P3

Station 117+20,

6.0

Existing Aggregate Base
Thickness (in)

3”-14” inches red scoria base
14”–5 feet dark brown to
brown, moist CH/CL with
minor gravel
3”-14” inches red scoria base
14”–5 feet dark brown to
brown, moist CH with minor
gravel
6”-14” inches red scoria base

right, in pullout
Hole #P4

Station 127+40,
Right

3.0

Hole #P5

Station 139+60,
roundabout

5.0

14”–5 feet olive green to
gray, sandy CH, moist to wet
3”-14” inches red scoria base
14”–5 feet dark brown,
sandy CH to CL, moist
5”-12” inches red scoria base
12”–5 feet dark brown,
sandy CL, moist

Observations:
The existing roadway in the area of the landslide has a gravel surface. There is no asphalt surfacing in this approximately 900-foot length of roadway. Where there is asphalt pavement, the pavement is 3 to 6 inches thick. About 9 inches of red scoria material was under the pavement. This material is commonly used in the region for base course, and is available locally. The soils in this area are clay and silty clay.
The soils classifications and R-values for the Holes are: P1: Soil type A-6(7), R-value = 19
P2: Soil type A-6(14)