Pavement Memorandum_SD FTNP BADL 10(9) .pdf

Memorandum

Subject: SD FTNP BADL 10(9)

Dillon Pass Embankment Repairs Pavement Recommendations

Date: January 8, 2018

From: Robert Norick

Staff Pavements/IA/Materials Engineer

To: Justin Henwood, PM/COE Steve Short, Lead Designer

Background:

This memorandum provides the pavement recommendations for the SD FTNP BADL 10(9) Dillon Pass Embankment Repairs including the Loop Road resurfacing between the Bigfoot Overlook and Bigfoot Road. The project is located on the 28-mile length of the Badlands Loop Road in the Badlands National Park, South Dakota. The asphalt, two lane Loop Road is the primary roadway within the national park and carries a significant amount of traffic. The vast majority of the vehicles that use this route are passenger cars, pickups, and SUVs; constituting approximately 93% of the daily traffic (based upon the previous pavement reports). There are occasional tour buses and freight trucks, as well as, recreational vehicles. Based upon the Cycle 6 (2017) road inventory program (RIP) data, the pavement condition rating (PCR) of the Badlands Loop Road is “good” to “excellent” with localized areas with “fair” ratings. The localized “fair” ratings are predominantly the result of higher pavement roughness due to depressions from settlement and heaves from swelling soils. There are no “poor” sections of pavement along the route.

Recommendations:

The project proposes embankment and drainage improvements at both the Dillon Pass and Bigfoot areas, as well as, resurfacing of the Loop Road between the Bigfoot Overlook and Bigfoot Road (1.1-mile length). The drainage improvements will likely include a few road cuts for the removal and installation of storm pipes. The Bigfoot road section includes a handful of areas with either depressions from settlement or heaves from swelling soils.

During the 1990’s, pavement and subgrade investigations were conducted for the 28-mile length of the Loop Road. CFL personnel logged the findings including soil description, pavement thickness, and aggregate base thickness. Subgrade samples were collected and tested at the CFLHD laboratory to determine the subgrade engineering properties. These investigations identified the subgrade soils to be high plasticity clays with R-Values less than 5 (some with high swell potential). The R-Value (resistance value) is a measure of a material’s resistance to deformation under load on a scale of 0 (water) to 100 (steel).

Following the 1990’s pavement investigations, the entire 28-mile length of the Loop Road was rehabilitated with a handful of projects. The construction plans and pavement reports from these previous projects were reviewed to determine the existing pavement section at both the Dillon Pass and Bigfoot areas. The Dillon Pass pavement section consists of 5 inches of asphalt pavement over 3 inches of cold in-place recycling (CIPR) and 9 inches of crushed aggregate base (CAB). The pavement section in the Bigfoot area consists of 3 inches of asphalt pavement over 4.5 inches of CIPR and 8 inches of CAB. Based upon the subgrade soils and the existing pavement sections, the following pavement structural sections are recommended for the Loop Road pavement cuts and resurfacing.

ASPHALT PATCHING FOR PAVEMENT CUTS (STORM PIPES)

4-inch deep Asphalt Pavement 12-inch deep Crushed Aggregate Base

BADLANDS LOOP ROAD RESURFACING

1-inch deep Asphalt Milling 2-inch deep Asphalt Overlay

A PG 64-28 binder is recommended for the project’s asphalt pavement. This binder is readily available and commonly used by South Dakota DOT. Being that the road’s PCR is controlled pavement roughness, it is recommended that a Type II-A roughness requirement be included in the Section 403 SCR in accordance with FP-14 Section 401.16(c) and Table 401-4. This will encourage the Contractor to strategically mill to minimize the existing heaves and depressions. To further minimize pavement roughness, it is recommended that a note be included on the plans allowing localized asphalt leveling courses. Additional recommendations include a tack coat applied to milled pavement and between asphalt lifts and a fog seal applied to the final pavement surface.

Recommended Pay Items for this Project:

Item Number Item Description Unit

30202-2000 Roadway Aggregate, Method 2 Ton 40301-0100 Asphalt Concrete Pavement, Type 1 Ton 40601-0000 Fog Seal Ton 41201-0000 Tack Coat Ton 41301-0200 Asphalt Pavement Milling, 1-Inch Depth Sqyd

The pay items above are to be constructed using the FP-14. Any changes to these items should be reflected in an addendum email or within the final report. Any applicable Special Contract Requirements will follow at a later time and under separate cover.

If you have any questions, please let us know.

CC: CFLHD Pavements & Materials Project Files: N:\SD\badl10(9)\Pavements\3. Reports-Tech Memos file://cflcadd3.cflhd.local/projects/SD/badl10(9)/Pavements/3.%20Reports-Tech%20Memos