KS_FLAP_RS_376(1)_Pavements_Report_Signed.pdf

19000 ROAD, BIG HILL LAKE ROAD

LABETTE COUNTY, KANSAS

KS FLAP RS 376(1)

PAVEMENT AND MATERIALS REPORT

AUGUST 2017

Report prepared by:

U.S. Department of Transportation Federal Highway Administration

Central Federal Lands Highway Division Lakewood, Colorado http://www.google.com/imgres?sa=X&biw=1280&bih=819&tbm=isch&tbnid=gtpyJEKxSQX6SM:&imgrefurl=http://portal.hud.gov/hudportal/HUD?src=/press/press_releases_media_advisories/2010/HUDNo.10-242&docid=0hzyuk4oobnONM&imgurl=http://portal.hud.gov/hudportal/images/hudimg?id=dot_logo_41193.jpg&w=520&h=528&ei=uGw7Uoy6Ksjk4AOC_IDQBw&zoom=1&iact=hc&vpx=567&vpy=131&dur=635&hovh=226&hovw=223&tx=151&ty=150&page=1&tbnh=154&tbnw=162&start=0&ndsp=30&ved=1t:429,r:26,s:0,i:171

KS FLAP RS 376(1) 19000 Road, Big Hill Lake Road ii

Written by: ________________________________________________________ Robert Norick, Staff Pavements & Materials Engineer

Reviewed by: ________________________________________________________ Mike Voth, Pavements & Materials Team Lead

Approved for distribution by:

Mike Voth, Pavements & Materials Team Lead Date

Electronic Distribution:

Construction Project Development Project Management Technical Services iii

TABLE OF CONTENTS

I. INTRODUCTION

II. CLIMATE

III. EXPLORATION

IV. EXISTING PAVEMENT & SOILS

V. PAVEMENT DESIGN

VI. PAVEMENT RECOMMENDATIONS & DISCUSSION

VII. MATERIALS RECOMMENDATIONS

APPENDICES

A – Location Maps and Climate Data B – Laboratory Reports & Calculations C – Photographs D – Aggregate Base & Pipe Design Criteria

I. INTRODUCTION

This report is written to document the existing road conditions and provide pavement recommendations for the planned KS FLAP RS 376(1) 19000 Road, Big Hill Lake Road project. The project consists of pavement reconstruction for the 6 mile length of 19000 Road between Anderson Road (west project limit) and Gray Road (east project limit) in Labette County in southeast Kansas (near the towns of Cherryvale and Parsons). Big Hill Lake (US Army Corps of Engineers) is a popular recreational attraction in Labette County. The majority of the visits to the lake are to the developed campgrounds, beach, and boat ramp that are accessed from 19000 Road, the only paved road in the area. The existing road is 22 feet in width with 10’ lanes and 1’ shoulders in each direction.

Vicinity and location maps for the project are provided in Appendix A.

II. CLIMATE

Climate data was obtained from the Intellicast.com website for Cherryvale, Kansas. The data is summarized in Table 1 below and provided in Appendix A. The average annual precipitation for this area is 45.44 inches. The project receives both snow and rain depending upon the time of year. The project elevations range from 822 feet to 942 feet.

Table 1. Weather Data

Month Average

HIGH

Record

HIGH

Average

LOW

Record

LOW

Average

PRECIP.

January 42 74 19 -20 1.59”

February 49 86 25 -16 1.81”

March 59 90 34 -6 3.69”

April 68 100 44 14 3.95”

May 77 95 54 28 6.00”

June 85 104 64 40 5.46”

July 92 116 68 47 3.78”

August 91 112 66 45 4.07”

September 82 108 58 27 4.85”

October 72 98 45 15 4.43” November 57 86 34 2 3.58” December 46 78 24 -18 2.23”

Temperatures are in °F and precipitations are in inches.

III. EXPLORATION

On January 24, 2017, a pavement and subgrade investigation was conducted for the project, including twenty-four shallow borings to depths of 5 feet. The road was drilled at approximately 1/4 mile increments, with boring locations alternating between lanes. CFL personnel logged the findings including depth of boring, visual soil description, pavement thickness, aggregate base thickness, areas of distress, and road width. During the site visit, eleven samples were collected. These samples were submitted to the CFLHD laboratory for testing to determine engineering properties. The laboratory results are provided in Appendix B.

IV. EXISTING PAVEMENT & SOILS

The existing roadway averages 22 feet in width with a riding surface of built up chip seals (1½” thick). The existing pavement was found to be in poor condition with extensive quantities of patching, rutting, bleeding, and alligator, longitudinal, and edge cracking. Beneath the built up chip seals is a 4” depth of compacted limestone aggregate base course over lean clays (drilled to 5’ depth). The pavement patches generally consist of a 3” to 6” depth of cold mix asphalt. Table 2 below summarizes the laboratory subgrade soil classifications (AASHTO M 145 and ASTM D 2487) for the aforementioned eleven soil samples.

Table 2. Laboratory Subgrade Soil Classifications Soil Boring Designation BH-3 BH-5 BH-7 BH-9

Milepost, Offset 0.6, 6’R 1.0, 6’L 1.5, 5’R 2.1, 6’R

AASHTO Classification A-4 (0) A-6 (3) A-7-6 (21) A-6 (9)

ASTM Group Symbol SC-SM CL CL CL

ASTM Group Name Silty clayey sand

Sandy lean clay

Lean clay with sand Lean clay

Soil Boring Designation BH-12 BH-13 BH-15 BH-16

Milepost, Offset 3.0, 6’L 3.2, 5’R 3.6, 6’L 3.8, 6’L

AASHTO Classification A-6 (16) A-6 (12) A-7-6 (20) A-7-6 (26)

ASTM Group Symbol CL CL CL CL

ASTM Group Name Lean clay Lean clay with sand

Lean clay with sand

Lean clay with sand

Soil Boring Designation BH-20 BH-21 BH-23

Milepost, Offset 5.0, 8’R 5.2, 6’L 5.7, 5’L

AASHTO Classification A-7-6 (18) A-6 (17) A-6 (9)

ASTM Group Symbol CL CL CL

ASTM Group Name Lean clay Lean clay Sandy lean clay

During the pavement and subgrade exploration, visual soil descriptions were recorded for all twenty-four borings as provided in Table 3 on the following page. The visual soil descriptions include the soil type, color, moisture condition (dry, moist, or wet), and consistency (very soft, soft, firm, hard, very hard) in accordance with ASTM D 2488.

Table 3. Field Soil Descriptions* Boring B-1 B-2 B-3 B-4 B-5 B-6 B-7 B-8

Milepost 0 0.3 0.6 0.7 1.0 1.3 1.5 1.8 Soil Type Clay Clay Clay Clay Clay Clay Clay Clay Soil Color Golden

Brown Golden Brown

Golden Brown

Golden Brown

Greyish Brown

Golden Brown

Golden Brown

Golden Brown

Moisture Moist Moist Moist Moist Wet Moist Moist Moist Consistency Firm Firm Firm Firm Soft Firm Firm Firm

Boring B-9 B-10 B-11 B-12 B-13 B-14 B-15 B-16 Milepost 2.1 2.3 2.6 3.0 3.2 3.4 3.6 3.8 Soil Type Clay Clay Clay Clay Clay Clay Clay Clay Soil Color Golden

Brown Golden Brown

Greyish Brown

Golden Brown

Golden Brown

Golden Brown

Golden Brown

Greyish Brown

Moisture Moist Moist Wet Dry Moist Moist Moist Wet Consistency Firm Firm Soft Firm Firm Firm Firm Soft

Boring B-17 B-18 B-19 B-20 B-21 B-22 B-23 B-24 Milepost 4.2 4.4 4.7 5.0 5.2 5.5 5.7 5.9 Soil Type Clay Clay Clay Clay Clay Clay Clay Clay Soil Color Greyish

Brown Golden Brown

Golden Brown

Golden Brown

Greyish Brown

Dark Brown

Dark Brown

Brown

Moisture Wet Dry Dry Dry Wet Moist Moist** Moist Consistency very soft Firm Firm Firm very soft Soft Soft Firm

* Based upon visual soil appearance; no testing performed.

** The Labette County Public Works mentioned that there is a shallow spring near BH-23.

As shown in Table 3, soft to very soft clay subgrade materials were identified along the following four sections of the roadway which will require precautions during construction to avoid the “sinking” of construction equipment and the “pumping” of the roadbed under construction traffic.

• Section 1 between Mileposts 0.85 to 1.25 (Soil Boring BH-5)

• Section 2 between Mileposts 2.40 to 2.70 (Soil Boring BH-11)

• Section 3 between Mileposts 3.75 to 4.35 (Soil Borings BH-16 and BH-17)

• Section 4 between Mileposts 5.15 to 5.85 (Soil Boring BH-21, BH-22, & BH-23)

V. PAVEMENT DESIGN

The 19000 Road project was scoped as a double chip seal; a pavement type with a 10-year design performance period. The chip seal pavement design for 19000 Road is based upon the “South Dakota Catalog Design Method” for gravel and chip seal roads as presented in the South Dakota Local Transportation Assistance Program Gravel Roads Maintenance and Design Manual (see Appendix D). This method designates the minimum thickness of road aggregate based upon two parameters; the subgrade support condition (low, medium, or high) and the number of “heavy” trucks per day in the design lane (0 to 5 trucks, 5 to 10 trucks, 10 to 25 trucks, or 25 to 50 trucks). A “heavy” truck is assumed to be a FHWA Class 6 vehicle (3-axle, single unit trucks such as dump trucks with a truck factor of 1.0), or larger, in accordance with Exhibit 11.2-A of the PDDM.

Subgrade Soil Conditions

Eleven subgrade soil samples were submitted for testing to determine their respective R-Values (AASHTO T 190). These test results and their calculated Resilient Modulus values are summarized in Tables 4 below. The subgrade Resilient Modulus is calculated from the R-Value using the following correlation equation for fine grained soils from the 1993 AASHTO Guide for Design of Pavement Structures (Equation 1.5.3, Page I-14).

Resilient Modulus, MR (psi) = 1,000 + 555 x (R-Value)

Table 4. 19000 Road Resilient Modulus Values

Sample Number Location R-Value Resilient Modulus

BH-3 Milepost 0.6 24 14,320 psi BH-5 Milepost 1.0 20 12,100 psi BH-7 Milepost 1.5 5 3,775 psi BH-9 Milepost 2.1 12 7,660 psi BH-12 Milepost 3.0 6 4,330 psi BH-13 Milepost 3.2 8 5,440 psi BH-15 Milepost 3.6 5 3,775 psi BH-16 Milepost 3.8 9 5,995 psi BH-20 Milepost 5.0 5 3,775 psi BH-21 Milepost 5.2 11 7,105 psi BH-23 Milepost 5.7 17 10,435 psi

Mean 11 7,105 psi

The project’s subgrade soils are generally classified as AASHTO A-6 and A-7 soils (see previous Section IV. Existing Pavement & Soils). AASHTO M 145 rates the project’s clayey soils as “poor” road subgrade material, and therefore, are considered a “low” subgrade support condition per the South Dakota Catalog Method.

Traffic

The 19000 Road (Big Hill Lake Road) is used primarily for recreational purposes, but does pass through farm land and there is a water treatment plant in the middle of the 6 mile section of roadway. Over 100 designated campsites are operated by the Corps of Engineers at Big Hill Lake with the majority of these being accessed from 19000 Road.

The road is classified as a major collector with a current two way average daily traffic (ADT) of 305 and a seasonal ADT of 500 (based upon the FLAP application and KSDOT traffic maps). The FLAP application also indicates that 90% of the current road ADT is related to Big Hill Lake users. As such, the vast majority of vehicles that use this route are passenger vehicles, pickups, SUVs, and recreational vehicles. Truck traffic is estimated at 5% of the ADT related to the water treatment plant and farm land. The road is a school bus route with no defined stop locations. The design lane traffic is estimated to be 60% of the two way ADT in accordance with Chapter 11 of the Federal Lands Highway (FLH) Project Development Design Manual (PDDM). The estimated daily number of “heavy” trucks in the design lane is 5% of the 305 ADT multiplied by the 60% directional distribution or 9 trucks per day.

Required Depth of Road Aggregate

Based upon the “South Dakota Catalog Design Method” Table 6 for “5 to 10” heavy trucks per day in combination with a “low” subgrade support conditions, the “suggested” minimum thickness of compacted aggregate base course is 8.5 inches (see Appendix D).

The existing depth of the chip seal and compacted base course is approximately 5.5”. The project proposes a full depth reclamation of the existing pavement and base course with the addition of a 3” depth of aggregate base to achieve the “suggested” minimum thickness.

VI. PAVEMENT RECOMMENDATIONS & DISCUSSION

Pavement Structural Section

The current FLAP project agreement provides for a construction cost of $1,200,000.

Based upon the current project budget, the following pavement structural section is recommended with an estimated 10-year performance period: the addition of a 3 inch depth of compacted aggregate base for the length and width of the roadway (FP-14 Section 302); full depth reclamation of the existing chip seal and aggregate base to a depth of 6 inches (SCR Section 304); and the installation of a double chip seal for the final pavement surface ((FP-14 Section 407).

Soft Subgrade Materials

Soft clay subgrade materials have been identified along sections of the roadway. The Contractor will need to select equipment and methods appropriate for these soft subgrade conditions in an effort avoid the “sinking” of construction equipment and the “pumping” of the roadbed under construction traffic.

Subexcavation

Soft clay subgrade materials have been identified along sections of the roadway. The Contractor is expected to use means and methods that prevent the need for subexcavation.

Due to budget constraints a limited amount of subexcavation quantities are included in the contract to be used at the discretion of the CO. Subexcavation should be to a depth of 2 feet with the placement of a geotextile separation fabric (Class 1, nonwoven, Type E) in the bottom of the excavation and the placement of 2 feet of select borrow material on top of the fabric. The typical subexcavation detail should be included in the plan set.

VII. MATERIALS RECOMMENDATIONS, SCRs, AND

CONSTRUCTION CONSIDERATIONS

Chip Seal

A Type 2B double chip seal with a grade CRS-1HP rapid setting polymer modified cationic emulsified asphalt is recommended for the project. The grade CRS-1HP emulsified asphalt is one of the standard emulsions for chip seals in Kansas.

Prime and Fog Seal

For this project, a medium-curing cutback asphalt (MC) prime coat applied to the base prior to the chip seal placement and an emulsified asphalt fog seal applied to the final chip seal pavement surface are recommended. A medium curing cutback asphalt provides a superior prime coat as compared to the standard emulsified asphalts.

Materials for Culvert Pipe

The project’s soils were found to be moderately corrosive with resistivity as low as 1190 ohm-cm. To address corrosion, it is recommended that galvanized steel pipe should have either a bituminous or polymer coating or a 14 gage wall thickness (see Appendix D).

Construction Scheduling and Execution

Construction should be scheduled for the months of July through September in an effort to minimize problems related to the soft clay subgrade materials. The majority of the soft subgrade materials are on the east half of the project, and therefore, it is recommended that construction progresses from east to west in an effort to provide the greatest flexibility for managing the construction budget.

SCRs and Construction Concerns

CFLHD’s standard SCRs related to pavements and materials are expected to be used with the exception of the following FP-14 sections: Section 304 Full Depth Reclamation;

Section 407 Chip Seal; Section 411 Asphalt Prime Coat; and Section 702 Asphalt Material. Any additional SCRs may be developed as needed. Based upon the soft clay subgrade materials along the roadway, a project specific Section 304 SCR permits a wider range of equipment (both light and heavy) for pulverizing, reconditioning, and scarifying the existing chip seal pavement and aggregate base to the standard 2” sieve requirement. The Contractor selects the equipment and methods appropriate for the project conditions. The Section 407 SCR specifies the Type 2B chip seals with a grade CRS-1HP emulsified asphalt. A project specific Section 411 SCR provides the specifications for the application of a medium-curing cutback asphalt (MC) prime coat.

A project specific Section 702 SCR provides the material specifications for the grade CRS-1HP emulsified asphalt.

Bid Items

Suggested FP-14 pay items for the proposed structural section are provided in Table 5.

Table 5 : Recommended Pay Items Item

Number Item Description Unit

20402-0000 Subexcavation CUYD 30202-2000 Roadway Aggregate, Method 2 TON 30402-5300 Full Depth Reclamation, Method 2, 6-Inch Depth SQYD 40601-0000 Fog Seal TON 40702-1200 Chip Seal, Type 2B SQYD 40711-0000 Emulsified Asphalt TON 40712-0000 Blotter TON 41101-1000 Prime Coat, Method 1 TON 41105-0000 Blotter TON

APPENDICES

A – Location Maps and Climate Data

B – Laboratory Reports & Calculations

C – Photographs

D – Aggregate Base & Pipe Design Criteria

APPENDIX A – Location Maps and Climate Data

LOCATION MAPS

Vicinity Map

Site Map with Project Limits

Climate Data

APPENDIX B – Laboratory Reports & Calculations

Resilient Modulus Calculation

Project: KS FLAP 376(1) - 19000 Road

Location: Labette County, Kansas

Date: 2/24/2017

Resilient

Boring # R-Value Modulus

BH-3 24 14,320

BH-5 20 12,100

BH-7 5 3,775

BH-9 12 7,660

BH-12 6 4,330

BH-13 8 5,440

BH-15 5 3,775

BH-16 9 5,995

BH-20 5 3,775

BH-21 11 7,105

BH-23 17 10,435

Mean 11 7,105 mailto:=@sum(h7:h24)

APPENDIX C – Photographs

Alligator Cracking & Patching at MP 0, BH-1, Looking Ahead

Alligator Cracking at MP 0, BH-1

Alligator Cracking & Patching at MP 0.6, BH-3, Looking Ahead

Subgrade Material at MP 0.6, BH-3, Golden Brown Silty Clayey Sand

Alligator Cracking & Bleeding at MP 1.0, BH-5, Brown Road Intx, Looking Ahead

4” Depth of Limestone Base over Greyish Brown Sandy Lean Clay at MP 1.0, BH-5

Alligator Cracking, Patching, & Bleeding at MP 1.5, BH-7, Looking Back

Subgrade Material at MP 1.5, BH-7, Golden Brown Sandy Lean Clay

Alligator Cracking, Patching, & Bleeding at MP 1.8, BH-8, Looking Ahead

Alligator Cracking, Patching, & Bleeding at MP 2.3, BH-10, Looking Ahead

Alligator Cracking & Patching at MP 2.6, BH-11, Downstream of Dam, Looking Ahead

Alligator Cracking & Patching at MP 3.0, BH-12, Douglas Road Intx, Looking Ahead

Typical Road Conditions at MP 3.2, BH-13 at Top of Dam Access Road

Typical Road Conditions at MP 3.6, BH-15 at USACE Recreational Entrance

Typical Road Conditions at MP 4.2, BH-17, Looking Ahead

Typical Road Conditions & Patching at MP 4.4, BH-18, Looking Back

Typical Road Conditions at MP 4.7, BH-19, Looking Back

Subgrade Material at MP 4.7, BH-19, Dry Golden Brown Lean Clay

Alligator Cracking, Patching, & Bleeding at MP 5.0, BH-20, Looking Back

Subgrade Material at MP 5.0, BH-20, Dry Golden Brown Lean Clay

Ponding Water & Patching at MP 5.2, BH-21, Looking Ahead

4” Depth of Limestone Base over Soft Greyish Brown Lean Clay at MP 5.2, BH-21

Alligator & Longitudinal Cracking at MP 5.5, BH-22, Looking Ahead

4” Depth of Limestone Base over Dark Brown Sandy Lean Clay at MP 5.7, BH-23

Location of Shallow Spring at MP 5.7, BH-23, Looking Ahead

Alligator Cracking, Patching, & Bleeding at MP 5.7, BH-23, Looking Back

APPENDIX D – Aggregate Base & Pipe Design Criteria

The South Dakota Catalog Design Method

Notes: 1 Low Subgrade support: CBR ≤3 percent;

Medium Subgrade support: 3 < CBR ≤ 10 percent;

High Subgrade support: CBR >10 percent.

Estimated Daily Number of Heavy Trucks Subgrade Support Condition1 Suggested Minimum Gravel Layer Thickness,mm (in.)

Low 165 (6.5)

0 to 5 Medium 140 (5.5)

High 115 (4.5)

Low 215 (8.5)

5 to 10 Medium 180 (7.0)

High 140 (5.5)

Low 290 (11.5)

10 to 25 Medium 230 (9.0)

High 180 (7.0)

Low 370 (14.5)

25 to 50 Medium 290 (11.5)

High 215 (8.5)

The South Dakota Catalog Design Method A11

A similar approach to the above procedure is suggested for local and other agencies in the state of South Dakota to deter-mine gravel layer thickness. The method is rather crude because it only relies on two parameters, heavy trucks and subgrade support condition. Table 6 represents suggested thicknesses. (3)

Table 6: Suggested Gravel Layer Thickness for New Or Reconstructed Rural Roads.

Hydrology and Hydraulics December 2012

7-48 Roadway Hydraulics

7.3.5.5 Recommended Methods

Design and evaluate the performance of energy dissipators according to the methods presented in HEC 14. HEC 14 also contains procedures for estimating scour hole dimensions at pipe outlets.

7.3.5.6 Reporting

The design of outlet protection for culvert, ditch, or storm drain outlets should be supported by documentation containing, at a minimum, the following information:

● Project identification

● Location of proposed installation

● Hydraulic design calculations

7.3.5.7 Plans

For the location and design of riprap outlet protection, prepare plans showing all details necessary to construct the improvements according to the hydraulic design, including the following:

● Location

● Dimensions and extent of riprap

● Gradation

● Bedding and Filter Material or Geotextile

● Grading or slope details

7.3.6 ALTERNATIVE PIPE MATERIALS

It is Federal Lands Highway policy to specify alternative drainage pipe materials on all projects where feasible and to comply with the provisions of 23 CFR 635.411. All suitable pipe materials, including reinforced concrete, steel, aluminum, and plastic will be considered as alternatives for all new cross culverts and storm drain pipes on Federal Lands Highway projects.

Not all pipe materials are appropriate or applicable for all storm drain applications. The design of alternative drainage pipe materials should consider functionally equivalent performance in three areas: structural capacity, durability and service life, and hydraulic capacity. The service life and hydraulic capacity issues are addressed in this section.

7.3.6.1 References

The following references provide source information for the development of the standards, criteria, and guidance of this subsection (most recent editions apply):

1. 23 CFR 635.411 Title 23 CFR 635.411 in 23 CFR 635D, General Material Requirements

Roadway Hydraulics 7-49

2. FHWA-FLP-91-006 FHWA, Durability of Special Coatings for Corrugated Steel Pipe, FHWA FLP-91-006

3. FHWA-RD-97-140 FHWA, Durability Analysis of Aluminized Type 2 Corrugated Metal Pipe, FHWA RD-97-140, 2000.

4. AASHTO HDG

Vol. IV

AASHTO Highway Drainage Guidelines, Volume IV – Hydraulic Design of Culverts

5. AASHTO HDG

Vol. XIV

AASHTO Highway Drainage Guidelines, Volume XIV – Culvert Inspection and Rehabilitation

6. Caltrans Chapter

California Department of Transportation Highway Design Manual, Chapter 850 – Physical Standards

7.3.6.2 Design Standards

7.3.6.2.1 Service Life

Design cross culvert and storm drain pipes with a minimum maintenance-free service life of 50-years, regardless of pipe material selection. A shorter service life may be used for temporary installations, and a longer service life may be considered in unusual situations.

7.3.6.2.2 Minimum Pipe Classification

Use Class II as the minimum for all reinforced concrete pipes. Determine appropriate pipe class from FLH fill height FLH Standard Drawings.

Use a minimum wall thickness of 0.0625” [1.63 mm] for all steel and aluminum pipes. The appropriate minimum structural metal thickness will be determined from approved FLH fill height tables.

7.3.6.3 Design Guidance

7.3.6.3.1 Service Life

The durability and service life of a storm drain pipe is directly related to the environmental conditions encountered at the site and the type of materials and coatings from which the pipe was fabricated. The two primary causes of early failure in drainage pipe materials are corrosion and abrasion.

Corrosion gradually wears away at the pipe walls by chemical action, and can occur from both the soil and water sides of the pipe. Abrasion wears away at the interior pipe wall by friction from suspended or bed-load sediment.

http://www.fhwa.dot.gov/publications/research/infrastructure/hydraulics/97140/97140.pdf http://www.fhwa.dot.gov/publications/research/infrastructure/hydraulics/97140/97140.pdf http://www.dot.ca.gov/hq/oppd/hdm/pdf/chp0850.pdf

7-50 Roadway Hydraulics

7.3.6.3.2 Data Collection

Corrosion

Representative pH and resistivity determinations are required in order to specify pipe materials capable of providing a maintenance-free service life. Samples are taken in accordance with the procedures described in AASHTO T 288 and T 289. Samples should be taken from both the soil and water side environments to ensure that the most severe environmental conditions are selected for determining the service life of the drainage pipe. Soil samples should be representative of backfill material anticipated at the drainage site. Avoid taking water samples during flood flows or for two days following flood flows to ensure more typical readings. In locations where streams are dry much of the year, water samples may not be possible or necessary. In areas of known uniform pH and resistivity readings, a random sampling plan may be developed to obtain the needed information.

In corrosive soil conditions where water side corrosion is not a factor, consider specifying less corrosive backfill material to modify the soil side environment. The mitigating effect of the specified backfill should be taken into account in making alternative pipe materials selections in situations where the soil side conditions control the design.

Abrasion

An estimate of the potential for abrasion is required in order to determine the need for invert protection. Four levels of abrasion are referred to in this guidance and the following guidelines are established for each level:

● Level 1. Nonabrasive conditions exist in areas of no bed load and very low velocities.

This is the condition assumed for the soil side of drainage pipes.

● Level 2. Low abrasive conditions exist in areas of minor bed loads of sand and velocities of 5 ft/s [1.5 m/s] or less.

● Level 3. Moderate abrasive conditions exist in areas of moderate bed loads of sand and gravel and velocities between 5 ft/s and 15 ft/s [1.5 m/s and 4.5 m/s].

● Level 4. Severe abrasive conditions exist in areas of heavy bed loads of sand, gravel, and rock and velocities exceeding 15 ft/s [4.5 m/s].

Abrasion levels are intended as guidance to help the engineer consider the impacts of bed-load wear on the invert of pipe materials. Sampling of the streambed materials is not required, but visual examination and documentation of the size of the materials in the stream bed and the average slope of the channel will give the designer guidance on the expected level of abrasion.

Where existing culverts are in place in the same drainage, the conditions of inverts should also be used as guidance. The expected stream velocity should be based upon a typical flow (i.e., 2-year flow and less) and not a 10-or 50-year design flood.

Roadway Hydraulics 7-51

7.3.6.3.3 Reinforced Concrete Pipe

Reinforced concrete pipe (AASHTO M 170M) is typically specified as an alternative whenever environmental conditions permit. The appropriate pipe class is determined from approved FLH fill height FLH Standard Drawings. If the following guidance on corrosion and abrasion limitations is used, reinforced concrete pipe can be assumed to have a minimum service life of 50 years.

Corrosion

Reinforced concrete pipe should not be specified for extremely corrosive conditions where the pH is less than 3.0 and the resistivity is less than 300 Ω-cm. Where the pH is less than 4.0, or the pipe is exposed to wetting and drying in a salt or brackish water environment, protective coatings (e.g., epoxy resin mortars, poly vinyl chloride sheets) should be used. When the sulfate concentration is greater than 0.2% in the soil or 2,000 parts per million in the water, Type V cement should be specified. When the sulfate concentration is greater than 1.5% in the soil or 15,000 parts per million in the water, Type V cement should be used with a sulfate resistant pozzolan. A higher cement ratio may also be used (e.g., AASHTO Class V pipe design).

Abrasion

On installations in severe abrasive environments, consider using seven or eight sack concrete or increasing the cover over the reinforcing steel.

7.3.6.3.4 Steel Pipe with Metallic Coatings

Steel pipe will typically be specified as an alternative when the environmental conditions permit.

The appropriate minimum structural metal thickness is determined from approved FLH fill height tables. Federal Lands Highway design policy assumes that steel pipe will provide a useful, maintenance-free service life for a period of time beyond the point of first perforation. This assumes an acceptable risk for most Federal Lands Highway projects, but at locations with erodible soils, large traffic volumes, or high fills where replacement or repair would be unusually difficult or expensive, consider increasing the steel plate by one standard thickness. In unusual situations where very high fills and severe abrasion are combined, or where other environmental concerns would make replacement of a pipe culvert very costly or impractical, consider using a pipe one size larger in diameter to permit re-lining in the future by insertion of another pipe.

The following types of steel pipe with metallic coatings are considered as alternatives on Federal Lands Highway projects:

● Galvanized steel (AASHTO M 218)

● Aluminum coated steel (Type 2) (AASHTO M 274)

Corrosion

Under non-abrasive and low-abrasive conditions, the service life of steel pipe with metallic coatings may be determined based upon corrosion (i.e., pH and resistivity) factors determined from Exhibit 7.3-B, which shows the relationship between service life and corrosion for plain

7-52 Roadway Hydraulics galvanized steel pipe. It has been adapted from the California Department of Transportation “Method for Estimating the Service Life of Steel Culverts,” California Test 643. The curves have been modified to show the expected average service life of pipe with a steel thickness of 0.0625” [1.63 mm] assuming a useful, maintenance-free service life 25 percent longer than the number of years to first perforation. Under moderate and severe abrasive conditions, abrasion protection must also be considered.

Under nonabrasive and low abrasive conditions, the metal thickness of galvanized and aluminum coated steel (Type 2) alternatives should be determined from Exhibit 7.3-B based on the resistivity and pH of the site. The minimum metal thickness of steel pipe, as determined from FLH standard fill height tables, may have to be increased, or the additional life of a protective coating may have to be added, in order to provide a 50-year service life. The results included in FHWA-FLP-91-006 indicate that within the environmental range of 5.0 through

9.0 pH and resistivity equal to or greater than 1500 Ω-cm, aluminum coated steel (Type 2) can be expected to give a service life of twice that of plain galvanized pipe.

Exhibit 7.3-B can be used to determine various combinations of increased thicknesses, aluminum coated steel (Type 2), and protective coatings to achieve a 50-year service life, but in no case may the metal thickness specified by the structural requirements be reduced.

Abrasion

Under nonabrasive and low abrasive conditions, the metal thickness of the galvanized, galvalume, and aluminum coated steel alternatives, as determined from Exhibit 7.3-B, should be used.

On installations in moderate abrasive environments where protective coatings are not required for corrosion protection, the thickness of the metal should be increased by one standard metal pipe thickness determined from the diagram for average service life of plain galvanized culverts (see Exhibit 7.3-B) or invert protection should be provided. Invert protection may consist of bituminous coating with invert paving with bituminous concrete, Portland cement concrete lining, installation of metal plates or rails, or velocity reduction structures.

On installations in severe abrasive environments where protective coatings are not required for corrosion protection, the thickness of the metal should be increased by one standard metal pipe thickness determined from the diagram for average service life of plain galvanized culverts (see Exhibit 7.3-B) and invert protection should be provided. Invert protection may consist of installation of metal plates or rails, or velocity reduction structures.

Protective coatings are not suitable for corrosion protection in moderate-abrasive and severe abrasive locations. Metal pipes should not be specified in moderate and severe abrasive environments where coatings are required to protect against water-side corrosion.

Roadway Hydraulics 7-53

Exhibit 7.3-B ESTIMATING STEEL PIPE SERVICES LIFE

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7-54 Roadway Hydraulics

7.3.6.3.5 Non-Metallic Protective Coatings for Steel Pipe

Protective coatings may be used to provide additional protection from corrosion or abrasion resulting in an extended service life. Coatings to protect against corrosion may only be used in non-abrasive and low abrasive environments.

The additional service life noted below in bold for each type of protective coating, for corrosion protection, are from Part V of FHWA-FLP-91-006. The added service is applicable only to non-abrasive and moderate abrasive conditions. All of the following types of steel pipe with non-metallic coatings are considered as alternatives on Federal Lands Highway projects:

Bituminous coating

Bituminous coatings (AASHTO M 190) can be expected to add 10 years of service to the water side and 25 years life to the soil side service life of pipe as determined from Exhibit 7.3-B.

Bituminous-coated pipe should not be used in low abrasive environments.

Bituminous paving and coating

Bituminous paved invert with bituminous coatings (AASHTO M 190) can be expected to add 25 years life to water side locations. Under moderate abrasive conditions, bituminous paved pipe may be used for invert protection where corrosion protection is not required.

Concrete lining

Concrete lining (ASTM A 849) can be expected to add 25 years of service life. Due to the natural cracking of concrete, the concrete lining should be applied over an asphalt coating if corrosion protection is needed. Under moderate abrasive conditions, concrete lined pipe may be used for invert protection where corrosion protection is not required.

Polymer coating

Ethylene Acrylic Acid Film coatings (AASHTO M245 and M246) should provide an additional 30 years service life with a 0.009” [0.25 mm] thickness.

Aramid fiber bonded coating

Only limited data is available for the service life of aramid fiber bonded coated (ASTM A 885) and epoxy coated pipes. No additional service life is currently credited with this policy.

7.3.6.3.6 Aluminum Alloy Pipe

Aluminum alloy pipe (AASHTO M 196M) will typically be specified as an alternative when environmental conditions permit. The appropriate minimum structural metal thickness is determined from approved FLH fill height tables. Within the following limits of corrosion and abrasion, aluminum alloy pipe can be assumed to have a service life of 50 years. Additional service life may be achieved where required by abrasion with the addition of protective coatings or additional metal thickness as discussed below:

Roadway Hydraulics 7-55

Corrosion

An aluminum alloy should be allowed if the pH is between four and nine and the resistivity is greater than 500 Ω-cm. An aluminum alloy alternative can also be considered for use in salt and brackish environments when embedded in granular, free draining material.

Abrasion

On installations in non-abrasive and low-abrasive environments, abrasion protection is not required.

On installations in moderately abrasive environments, the thickness should be increased by one standard metal thickness or invert protection should be used. Invert protection may consist of bituminous coating and invert paving with bituminous concrete or Portland cement concrete, installation of metal plates or rails, or velocity reduction structures.

On installations in severe abrasive environments, the thickness of the metal should be increased by one standard metal pipe thickness from that determined for low-abrasive conditions and invert protection should be provided. Invert protection may consist of installation of metal plates or rails or velocity reduction structures.

7.3.6.3.7 Plastic Pipe

Polyethylene and polyvinyl chloride plastic pipe may be specified as alternatives for pipe diameters and minimum resin cell classifications shown in the AASHTO’s Standard Specifications for Highway Bridges, Division I Design, Section 18, Soil Thermoplastic Pipe Interaction Systems. The thickness of the plastic alternatives must meet the structural requirements of AASHTO’s Standard Specifications. The assumed service life of plastic pipe designed in accordance with AASHTO Section 18 is 50 years. The maximum allowable fill heights for pipe materials listed below is determined from approved FLH standard fill-height tables which include the following plastic pipe materials:

● Smooth wall polyethylene (ASTM F 714)

● Corrugated polyethylene (AASHTO M 294)

● Ribbed polyethylene (ASTM F 894)

● Smooth wall polyvinyl chloride (AASHTO M 278 and ASTM F 679)

● Ribbed polyvinyl chloride (AASHTO M304 and ASTM F 794)

Corrosion

Plastic alternatives may be specified without regard to the resistivity and pH of the site.

Abrasion

Under nonabrasive and low-abrasive conditions, polyethylene and polyvinyl chloride alternatives should be allowed. Plastic alternatives should not be used under moderate and severe abrasive conditions without invert protection.

7-56 Roadway Hydraulics

Maximum Size

Limit the size of plastic pipe to 48” [1200 mm] under mainline roads.

The locations selected for use of plastic pipes should address partner agency concerns of possible damage due to fire, ultraviolet sunlight, and rodents.

7.3.6.4 Recommended Methods

Design and evaluate the design service life for galvanized steel culvert and storm drain pipes by the Modified California method presented in Exhibit 7.3B. Refer to FHWA-RD-97-140, Durability Analysis of Aluminized Type 2 Corrugated Metal Pipe, for design guidance on aluminized material.

7.3.6.5 Reporting

Documentation of the design service life of culvert and storm drain pipes should be included in the design reporting.

7.3.6.6 Plans

For culvert and storm drain pipes, include information on pipe material, size, class, gauge, and any special coatings in the Plan Drainage Summary.