+-----------------------------------------------------------------------+
| # DIVISION 250                                                        |
|                                                                       |
| **SLOPE REINFORCEMENT**                                               |
|                                                                       |
| **AND RETAINING WALLS**                                               |
+-----------------------------------------------------------------------+

## Section 251. --- RIPRAP

Description

**251.01** This work consists of furnishing and placing riprap for bank
protection, slope protection, drainage structures, and erosion control.

Riprap classes are designated as shown in Table 705-1.

Material

**251.02** Conform to the following Subsections:

Geotextile type IV 714.01

Cement grout 725.22(e)

Riprap rock 705.02

Construction Requirements

**251.03 General.** Perform the work under Section 209. Dress the slope
to produce a smooth surface. If earthwork geotextile is required, place
according to Section 207.

**251.04 Placed Riprap.** Placed riprap is rock placed on a prepared
surface to form a well‑graded mass.

Place riprap to its full thickness in one operation to avoid displacing
the underlying material. Do not place riprap material by methods that
cause segregation or damage to the prepared surface. Place or rearrange
individual rocks by mechanical or hand methods to obtain a dense uniform
blanket with a reasonably smooth surface.

**251.05 Keyed Riprap.** Keyed riprap is rock placed on a prepared
surface and set into place by impact pressure.

Place rock for keyed riprap according to Subsection 251.04. Set the
riprap into place by exerting impact pressure with a hydraulic-powered
bucket or an approximate 2000‑kilogram flat-faced mass. Repeated impacts
should be made until the rock is firmly seated and forms a reasonably
uniform surface without reducing the effective sizes of the rocks. Do
not use impact pressure on riprap below the water surface.

**251.06 Grouted Riprap.** Grouted riprap is rock placed or keyed on a
prepared surface with the voids filled with grout.

Place rock for grouted riprap according to Subsections 251.04 or 251.05.
Thoroughly moisten the rocks and wash excess fines from the riprap or to
the underside of the riprap. Place grout only when the air temperature
is no less than 1 ºC within the near-surface voids of the riprap. Place
the grout in a manner to prevent segregation. Begin placing grout at the
lowest elevation of the riprap. Fill all voids without unseating the
rocks. Do not exceed 1.5-meter thickness for each layer of grouted
riprap. Allow 3 days curing time before adding the next layer of riprap
and grout. Provide weep holes through the grouted riprap as required.
Keep the grouted riprap moist for 3 days after the work is completed and
protect it from freezing for a minimum of 7 days after grouting.

**251.07 Acceptance.** See Table 251-1 for sampling and testing
requirements.

Rock for riprap will be evaluated under Subsection 106.02 and 106.03.

Rock placement for riprap will be evaluated under Subsections 106.02 and
106.04.

Structure excavation and backfill will be evaluated under Section 209.

Geotextile will be evaluated under Section 207.

Material for grout will be evaluated under Subsections 106.02 and
106.03. Grout will be evaluated under Subsections 106.02 and 106.04.
Grout placement will be evaluated under Subsection 106.02.

Measurement

**251.08** Measure the Section 251 items listed in the bid schedule
according to Subsection 109.02 and the following as applicable.

Measure riprap by the cubic meter in place.

Payment

**251.09** The accepted quantities will be paid at the contract price
per unit of measurement for the Section 251 pay items listed in the bid
schedule. Payment will be full compensation for the work prescribed in
this Section. See Subsection 109.05.

+----------+---------+----------+--------+-------+-----+--------------+
| Table    | **Re    | Before   | "      | "     | "   | Before using |
| 251-1    | porting | using    |        |       |     |              |
|          | Time**  |          |        |       |     | in work      |
| Sampling |         | in work  |        |       |     |              |
| and      |         |          |        |       |     |              |
| Testing  |         |          |        |       |     |              |
| Requ     |         |          |        |       |     |              |
| irements |         |          |        |       |     |              |
+----------+---------+----------+--------+-------+-----+--------------+
|          | **      | Yes      | "      | "     | "   | Yes, when    |
|          | Split** |          |        |       |     | requested    |
|          |         |          |        |       |     |              |
|          | **S     |          |        |       |     |              |
|          | ample** |          |        |       |     |              |
+----------+---------+----------+--------+-------+-----+--------------+
|          | **Point | Source   | "      | "     | "   | ---          |
|          | of      | of       |        |       |     |              |
|          | Sam     | material |        |       |     |              |
|          | pling** |          |        |       |     |              |
+----------+---------+----------+--------+-------+-----+--------------+
|          | **Sam   | 1 per    | "      | "     | "   | 1 per mix    |
|          | pling** | material |        |       |     | design       |
|          |         | type     |        |       |     |              |
|          | **Freq  |          |        |       |     |              |
|          | uency** |          |        |       |     |              |
+----------+---------+----------+--------+-------+-----+--------------+
|          | **Test  | AASHTO T | AASHTO | A     | AAS | AASHTO T 23  |
|          | Methods | 85       | T 210  | ASHTO | HTO |              |
|          | Sp      |          |        | T 104 | T   | & T 22       |
|          | ecifica |          |        |       | 96  |              |
|          | tions** |          |        |       |     |              |
+----------+---------+----------+--------+-------+-----+--------------+
|          | **Cat   | ---      | ---    | ---   | --- | ---          |
|          | egory** |          |        |       |     |              |
+----------+---------+----------+--------+-------+-----+--------------+
|          | **Ch    | Apparent | Coarse | S     | LA  | Making test  |
|          | aracter | specific | dura   | odium | ab  | specimens    |
|          | istic** | gravity  | bility | su    | ras | Compressive  |
|          |         | &        | index  | lfate | ion |              |
|          |         | ab       |        | soun  |     | strength     |
|          |         | sorption |        | dness |     |              |
+----------+---------+----------+--------+-------+-----+--------------+
|          | **Type  | Measured |        |       |     | Measured and |
|          | of      | and      |        |       |     | tested       |
|          | Accep   | tested   |        |       |     |              |
|          | tance** |          |        |       |     | for          |
|          |         | for      |        |       |     | conformance  |
|          | **      | con      |        |       |     | (106.04)     |
|          | (Subsec | formance |        |       |     |              |
|          | tion)** | (106.04) |        |       |     |              |
+----------+---------+----------+--------+-------+-----+--------------+
|          | **M     | Riprap   |        |       |     | Mortar       |
|          | aterial |          |        |       |     |              |
|          | or      | (705.02) |        |       |     |              |
|          | Pr      |          |        |       |     |              |
|          | oduct** |          |        |       |     |              |
+----------+---------+----------+--------+-------+-----+--------------+

## Section 252. --- SPECIAL ROCK EMBANKMENT AND

## ROCK BUTTRESS

Description

**252.01** Special rock embankment work consists of furnishing and
placing hand-placed or mechanically-placed rock in fill sections. Rock
buttress work consists of furnishing and placing hand-placed or
mechanically-placed rock in cut sections.

Special rock embankments and rock buttresses are designated as
hand-placed or mechanically-placed.

Material

**252.02** Conform to the following Subsections:

Rock for buttresses 705.05

Rock for special rock embankment 705.04

Construction Requirements

**252.03 Placing Rock.** Perform the work under Section 204 or 209 as
required.

Place the rock in a stable orientation with minimal voids. Offset the
rock to produce a random pattern. Use spalls smaller than the minimum
rock size to chock the larger rock solidly in position and to fill voids
between the large rock.

Construct the exposed face of the rock mass reasonably uniform with no
projections beyond the line of the slope that are more than 300
millimeters for mechanically-placed rock or 150 millimeters for
hand‑placed rock.

**252.04 Acceptance.** Rock for special rock embankment and rock
buttress will be evaluated under Subsection 106.02.

Rock placement for special rock embankment and rock buttress will be
evaluated under Subsections 106.02 and 106.04.

Structure excavation and backfill will be evaluated under Section 209.

Measurement

**252.05** Measure the Section 252 items listed in the bid schedule
according to Subsection 109.02 and the following as applicable.

Measure special rock embankment and rock buttress by the cubic meter in
place.

Payment

**252.06** The accepted quantities will be paid at the contract price
per unit of measurement for the Section 252 pay items listed in the bid
schedule. Payment will be full compensation for the work prescribed in
this Section. See Subsection 109.05.

## Section 253. --- GABIONS AND REVET MATTRESSES

Description

**253.01** This work consists of constructing gabion structures and
revet mattresses.

Material

**253.02** Conform to the following Subsections:

Backfill material 704.03

Gabion and revet mattress material 720.02

Gabion and revet mattress rock 705.01

Geotextile type IV 714.01

Structural backfill 704.04

Construction Requirements

**253.03 General.** Survey according to Section 152 and verify the
limits of the wall installation. Prepare and submit installation
drawings according to Subsection 104.03. Perform the work under Section
209.

**253.04 Basket Assembly.** Do not damage wire coatings during basket
assembly, structure erection, cell filling, or backfilling. Rotate the
basket panels into position and join the vertical edges with fasteners
according to Subsection 253.05. Temporary fasteners may be used for
basket assembly if they are supplemented during structure erection with
permanent fasteners according to Subsection 253.05.

Rotate the diaphragms into position and join the vertical edges
according to Subsection 253.05.

**253.05 Structure Erection.** Place the empty gabion baskets on the
foundation and interconnect the adjacent baskets along the top and
vertical edges using permanent fasteners.

Where lacing wire is used, wrap the wire with alternating single and
double loops every other mesh opening and not more than 150 millimeters
apart. Where spiral binders are used, crimp the ends to secure the
binders in place. Where alternate fasteners are used, space the
fasteners in every mesh opening and not more than 150 millimeters apart.

In the same manner, interconnect each vertical layer of baskets to the
underlying layer of baskets along the front, back, and sides. Stagger
the vertical joints between baskets of adjacent rows and layers by at
least one cell length.

**253.06 Cell Filling.** Remove all kinks and folds in the wire mesh,
and properly align all the baskets. Place rock carefully in the basket
cells to prevent bulging of the baskets and to minimize voids in the
rock fill. Maintain the basket alignment.

Place internal connecting wires in each unrestrained exterior basket
cell greater than 0.3 meter in height. This includes interior basket
cells left temporarily unrestrained. Place internal connecting wires
concurrently with rock placement.

Fill the cells in any row or layer so that no cell is filled more than
0.3 meter above an adjacent cell. Repeat this process until the basket
is full and the lid bears on the final rock layer.

Secure the lid to the sides, ends, and diaphragms according to
Subsection 253.05. Make all exposed basket surfaces smooth and neat with
no sharp rock edges projecting through the wire mesh.

**253.07 Backfilling.** Place a geotextile over the back face of the
gabion structure. Concurrently with the cell filling operation, backfill
the area behind the gabion structure with structural backfill according
to Subsection 209.10. Compact each layer according to Subsection 209.11
except use an acceptable lightweight mechanical or vibratory compactor
within one meter of the gabion structure.

**253.08 Revet Mattresses.** Place a geotextile according to Section
207. Construct revet mattresses according to Subsections 253.04 through
253.06. Anchor the mattresses in place. Place geotextile against the
vertical edges of the mattress and backfill against the geotextile using
backfill material or other approved material. Overfill revet mattresses
by 30 to 50 millimeters.

**253.09 Acceptance.** See Table 209-1 for sampling and testing
requirements.

Material for gabion structures and revet mattresses will be evaluated
under Subsections 106.02 and 106.03.

Construction of gabion structures and revet mattresses will be evaluated
under Subsections 106.02 and 106.04.

Survey work will be evaluated under Section 152.

Geotextile will be evaluated under Subsection 207.

Structure excavation, structural backfill, and backfill material will be
evaluated under Section 209.

Measurement

**253.10** Measure the Section 253 items listed in the bid schedule
according to Subsection 109.02 and the following as applicable.

Measure gabions by the square meter of front wall face or by the cubic
meter in the structures.

Measure foundation fill under Section 208.

Payment

**253.11** The accepted quantities will be paid at the contract price
per unit of measurement for the Section 253 pay items listed in the bid
schedule. Payment will be full compensation for the work prescribed in
this Section. See Subsection 109.05.

## Section 254. --- CRIB WALLS

Description

**254.01** This work consists of constructing concrete, metal, or timber
crib retaining walls.

Material

**254.02** Conform to the following Section and Subsections:

Bed course 704.09

Concrete 601

Crib wall backfill 704.12

Hardware for timber structures 716.02

Metal bin type crib walls 720.03

Precast concrete units 725.11(c)

Reinforcing steel 709.01

Structural backfill 704.04

Treated structural timber and lumber 716.03

Construction Requirements

**254.03 General.** Survey according to Section 152 and verify the
limits of the wall installation. Prepare and submit installation
drawings according to Subsection 104.03. Perform the work under Section
209. When the wall is set on a rocky foundation, place 200 millimeters
of bed course under the wall base elements.

**254.04 Erection.** Furnish all necessary bolts, nuts, and hardware for
complete assembly of the units into a continuous wall of connected
units. Erect the crib wall according to the fabricator\'s or
manufacturer\'s instructions. On curves, obtain the proper curvature for
the face by using shorter stringers in the front or rear panels.
Construct the wall to within 25 millimeters in 3 meters from the lines
and elevations shown on the plans.

**(a) Concrete crib wall.** Remove and replace all concrete members that
are cracked or damaged.

**(b) Metal crib wall.** Torque bolts for metal crib walls to at least
34 newton meters.

**(c) Timber crib wall.** Construct timber cribs according to Section
557.

**254.05 Backfilling.** Backfill within the cribs with crib wall
backfill according to Subsection 209.10. Backfill behind the cribs with
structural backfill according to Subsection 209.10. Maintain an equal
level of backfill within and behind the cribs during the backfilling
process. Compact each layer according to Subsection 209.11 except use an
acceptable lightweight mechanical or vibratory compactor within one
meter of the crib wall face.

**254.06 Acceptance.** Material for crib walls will be evaluated under
Subsections 106.02 and 106.03. Furnish a production certification with
each shipment for the following:

**(a)** Metal bin type crib walls;

**(b)** Precast concrete units;

**(c)** Reinforcement steel; and

**(d)** Treated structural timber and lumber.

Concrete, metal, or timber crib retaining wall construction will be
evaluated under Subsections 106.02 and 106.04.

Survey work will be evaluated under Section 152.

Structure excavation, crib wall backfill, structural backfill, and bed
course material will be evaluated under Section 209.

Concrete crib walls will be evaluated under Section 601.

Timber crib walls will be evaluated under Section 557.

Measurement

**254.07** Measure the Section 254 items listed in the bid schedule
according to Subsection 109.02 and the following as applicable.

Measure crib walls by the square meter of front wall face.

Measure crib wall backfill by the cubic meter in place.

Measure foundation fill under Section 208.

Payment

**254.08** The accepted quantities will be paid at the contract price
per unit of measurement for the Section 254 pay items listed in the bid
schedule. Payment will be full compensation for the work prescribed in
this Section. See Subsection 109.05.

## Section 255. --- MECHANICALLY-STABLILIZED EARTH WALLS

Description

**255.01** This work consists of constructing mechanically-stabilized
earth walls.

Material

**255.02** Conform to the following Section and Subsections:

Concrete leveling pad 601

Geotextile type IV 714.01

Mechanically-stabilized earth wall material 720.01

Select granular backfill 704.10

Structural backfill 704.04

Construction Requirements

**255.03 General.** Survey according to Section 152, and verify the
limits of the wall installation. Prepare and submit installation
drawings according to Subsection 104.03. Perform the work under Section
209. Grade the foundation for a width equal to the length of reinforcing
elements plus 0.5 meter. Where the wall is set on a rocky foundation,
place 150 millimeters of select granular backfill under the reinforcing
mesh or strips.

For concrete-faced walls, provide a precast reinforced or a
nonreinforced cast-in-place concrete leveling pad. Cure cast-in-place
leveling pads a minimum of 12 hours before placing wall panels.

**255.04 Wall Erection.** Erect the wall according to the drawings and
the manufacturer\'s recommendations. When requested, have an experienced
field representative from the wall system manufacturer available during
erection.

**(a) Concrete-faced walls**. Erect panels by means of lifting devices
connected to the upper edge of the panel. Align precast facing panels
within 19 millimeters vertically and horizontally when measured with a
3-meter straightedge.

Make the joint openings 19±6 millimeters wide. Install joint material
according to the drawings. Cover all joints on the backside of the
panels with a 300-millimeter wide strip of geotextile. Overlap
geotextile splices a minimum of 100 millimeters.

Hold the panels in position with temporary wedges or bracing during
backfilling operations. Erect the wall so the overall vertical tolerance
(top to bottom) does not exceed 13 millimeters per 3 meters of wall
height.

**(b)** **Wire-faced walls.** Place backing mats and 6-millimeter
hardware cloth in successive horizontal lifts as backfill placement
proceeds. Connect, tighten, and anchor soil reinforcement elements to
the wall facing units before placing backfill. Do not exceed an
individual lift vertical tolerance and an overall wall (top to bottom)
vertical tolerance of 25 millimeters per 3 meters of wall height. Place
reinforcement elements within 25 millimeters vertically above the
corresponding connection elevation at the wall face. Do not place
reinforcing elements below the corresponding connection elevations. Do
not deviate from the designed batter of the wall by more than 25
millimeters per 3 meters of wall height. Do not deviate more than
50 millimeters at any point in the wall from a 3-meter straightedge
placed horizontally on the theoretical plane of the design face.

**(c) Gabion-faced walls.** Place the first lift of backfill before
filling the gabion baskets. Construct gabion structures according to
Section 253. Lay reinforcement mesh horizontally on compacted fill and
normal to the face of the wall. Connect the gabion facing unit to
reinforcement mesh with spiral binders or tie wire at 100‑millimeter
nominal spacing with alternating single and double locked loops. Pull
and anchor the reinforcement mesh taut before placing additional
backfill.

**255.05 Backfilling.** Backfill the stabilized volume with select
granular backfill according to Subsection 209.10. Ensure that no voids
exist below the reinforcing mesh or strips. Compact each layer according
to Subsection 209.11, except use an acceptable lightweight mechanical or
vibratory compactor within one meter of the wall face. Where the
stabilized volume supports spread footings for bridges or other
structural loads, compact the top 1.5 meters to at least 100 percent of
the maximum density.

Do not damage or disturb the facing or reinforcing elements. Do not
operate equipment directly on top of the reinforcing mesh or strips.
Correct all damaged, misaligned, or distorted wall elements.

Backfill and compact behind the stabilized volume with structural
backfill according to Subsection 209.10. At the end of the day\'s
operation, slope the last lift of backfill away from the wall face to
direct surface runoff away from the wall. Do not allow surface runoff
from adjacent areas to enter the wall construction area.

**255.06 Acceptance.** Material for mechanically-stabilized earth walls
listed under Subsection 720.01 will be evaluated under Subsections
106.02 and 106.03. Furnish a production certification with each shipment
of concrete face panels.

Construction of mechanically-stabilized earth wall and services will be
evaluated under Subsections 106.02 and 106.04.

Survey work will be evaluated under Section 152.

Geotextile will be evaluated under Section 207.

Structure excavation, select granular backfill, and structural backfill
will be evaluated under Section 209.

Gabions will be evaluated under Section 253.

Concrete leveling pad will be evaluated under Section 601.

Measurement

**255.07** Measure the Section 255 items listed in the bid schedule
according to Subsection 109.02 and the following as applicable.

Measure mechanically-stabilized earth walls by the square meter of front
wall face.

Measure select granular backfill within the stabilized volume by the
cubic meter in place.

Measure foundation fill under Section 208.

Payment

**255.08** The accepted quantities will be paid at the contract price
per unit of measurement for the Section 255 pay item listed in the bid
schedule. Payment will be full compensation for the work prescribed in
this Section. See Subsection 109.05.

+-------+-------+-----------+----------+----------+----------+-------+
| Table | *     | Before    | "        | "        | Before   | \(1\) |
| 255-1 | *Repo | using     |          |          |          | Mi    |
|       | rting |           |          |          | placing  | nimum |
| Sam   | T     | in work   |          |          | next     | of 5  |
| pling | ime** |           |          |          | layer    | p     |
| and   |       |           |          |          |          | oints |
| Te    |       |           |          |          |          | per   |
| sting |       |           |          |          |          | pro   |
| Re    |       |           |          |          |          | ctor. |
| quire |       |           |          |          |          |       |
| ments |       |           |          |          |          |       |
+-------+-------+-----------+----------+----------+----------+-------+
|       | **Sp  | Yes       | "        | "        | ---      |       |
|       | lit** |           |          |          |          |       |
|       |       |           |          |          |          |       |
|       | **Sam |           |          |          |          |       |
|       | ple** |           |          |          |          |       |
+-------+-------+-----------+----------+----------+----------+-------+
|       | **    | Source of | "        | "        | In-place |       |
|       | Point |           |          |          |          |       |
|       | of    | material  |          |          |          |       |
|       | Sampl |           |          |          |          |       |
|       | ing** |           |          |          |          |       |
+-------+-------+-----------+----------+----------+----------+-------+
|       | **    | 1 per     | "        | "        | 2 per    |       |
|       | Sampl | soil type |          |          | lift     |       |
|       | ing** |           |          |          |          |       |
|       |       |           |          |          |          |       |
|       | **F   |           |          |          |          |       |
|       | reque |           |          |          |          |       |
|       | ncy** |           |          |          |          |       |
+-------+-------+-----------+----------+----------+----------+-------+
|       | *     | AASHTO M  | AASHTO T | AASHTO T | AASHTO T |       |
|       | *Test | 145       | 27       | 180,     | 310 or   |       |
|       | Me    |           |          |          |          |       |
|       | thods |           | & T 11   | method   | other    |       |
|       | S     |           |          | D^(1)^   | approved |       |
|       | pecif |           |          | or       | pr       |       |
|       | icati |           |          |          | ocedures |       |
|       | ons** |           |          | T 99,    |          |       |
|       |       |           |          | method   |          |       |
|       |       |           |          | C^(1)^   |          |       |
+-------+-------+-----------+----------+----------+----------+-------+
|       | **    | ---       | ---      | ---      | ---      |       |
|       | Categ |           |          |          |          |       |
|       | ory** |           |          |          |          |       |
+-------+-------+-----------+----------+----------+----------+-------+
|       | **C   | Class     | G        | M        | Co       |       |
|       | harac | ification | radation | oisture- | mpaction |       |
|       | teris |           |          |          |          |       |
|       | tic** |           |          | density  |          |       |
+-------+-------+-----------+----------+----------+----------+-------+
|       | *     | Measured  |          |          |          |       |
|       | *Type | and       |          |          |          |       |
|       | of    | tested    |          |          |          |       |
|       | Accep |           |          |          |          |       |
|       | tance | for       |          |          |          |       |
|       | (Sub  | co        |          |          |          |       |
|       | secti | nformance |          |          |          |       |
|       | on)** | (106.04)  |          |          |          |       |
+-------+-------+-----------+----------+----------+----------+-------+
|       | **Mat | Backfill  |          |          |          |       |
|       | erial |           |          |          |          |       |
|       | or    | \(704\)   |          |          |          |       |
|       | Prod  |           |          |          |          |       |
|       | uct** |           |          |          |          |       |
+-------+-------+-----------+----------+----------+----------+-------+

##  {#section .unnumbered}

## Section 256. --- PERMANENT GROUND ANCHORS

Description

**256.01** This work consists of constructing permanent ground anchors.

Material

**256.02** Conform to the following Subsection:

Ground anchors 722.02

Grout 722.02(e)

Construction Requirements

**256.03 Qualifications.** The Contractor or subcontractor performing
the ground anchor work shall have completed at least 5 permanent ground
anchor projects within the last 3 years. Submit a brief description of
each project including the owning agency\'s name and current telephone
number.

Provide a professional engineer with at least 3 years experience in the
design and construction of permanent ground anchors. Provide on-site
supervisors and drill operators with at least 1 year experience
installing permanent ground anchors. At least 30 days before starting
ground anchor work, identify the professional engineer, on-site
supervisors, and drill operators assigned to the project and submit a
summary of each individual\'s experience.

**256.04 Drawings.** At least 30 days before starting ground anchor
work, submit drawings according to Subsection 104.03. Include the
following:

**(a)** A ground anchor schedule giving the following information:

**(1)** Ground anchor number;

**(2)** Ground anchor design load;

**(3)** Type and size of tendon;

**(4)** Minimum total anchor length;

**(5)** Minimum bond length;

**(6)** Minimum tendon bond length; and

**(7)** Minimum unbonded length.

**(b)** Include the following details in the ground anchor system
drawings:

**(1)** Spacers and their location;

**(2)** Centralizers and their location;

**(3)** Unbonded length corrosion protection system;

**(4)** Bond length corrosion protection system;

**(5)** Transition between the unbonded length and the bond length
corrosion protection systems;

**(6)** Anchorage and trumpet; and

**(7)** Anchorage corrosion protection system.

**256.05 Tendon Fabrication.**

**(a) General.** Fabricate the tendons in either the shop or field as
indicated on the drawings. Size the tendon so:

**(1)** The design load does not exceed 60 percent of the minimum
required ultimate tensile strength of the tendon; and

**(2)** The maximum test load does not exceed 80 percent of the minimum
specified ultimate tensile strength of the tendon.

**(b)** **Bond length.** Determine the bond length necessary to develop
the design load indicated on the drawings. Use a minimum tendon bond
length of 3 meters in rock and 4.5 meters in soil. Provide corrosion
protection of the tendon bond length with a cement grout cover.

Where encapsulation of the tendon is required, protect the tendon bond
length from corrosion by encapsulating it in a grout-filled corrugated
plastic or deformed steel tube or by coating it with fusion-bonded
epoxy. Place the grout inside the tube either before or after the tendon
is placed in the drill hole. Centralize the tendon within the tube with
a minimum 2.5 millimeter grout cover.

**(c) Centralizers.** Use spacers along the tendon bond length of a
multi-element tendon to separate each of the individual elements of the
tendon. Use centralizers to ensure a minimum of 13 millimeters of grout
cover over the tendon bond length or tendon bond length encapsulation as
appropriate. Use centralizers that do not impede the free flow of grout
up the bore hole. Position centralizers so their center-to-center
spacing does not exceed 3 meters.

Locate the upper centralizer a maximum of 1.5 meters from the top of the
tendon bond length. Locate the lower centralizer a maximum of 300
millimeters from the bottom of the tendon bond length.

Centralizers are not required on pressure-injected tendons if the ground
anchor is installed in coarse-grained soils using grouting pressures
greater than 1 megapascal.

Centralizers are not required on hollow-stem-augered tendons if the
ground anchor is grouted through the auger and the hole is maintained
full of a stiff grout during extraction of the auger. A grout is
considered *\"stiff\"* if its slump is less than 225 millimeters.

**(d) Unbonded length**. Provide minimum unbonded length of 4.5 meters.

**(1)** If the entire drill hole is grouted in one operation, provide
corrosion protection of the unbonded length with a sheath completely
filled with corrosion-inhibiting grease or grout, or a heat-shrinkable
tube internally coated with an elastic adhesive.

If grease is used under the sheath, completely coat the unbounded tendon
length, fill spaces between individual elements of multi-element tendon
with grease, and provide measures to prevent grease from escaping at the
ends of the sheath.

If the sheath is grout filled, provide a separate bondbreaker along the
unbonded length of the tendon.

**(2)** If a grease-filled sheath corrosion protection is provided and
the drill hole above the bond length is grouted after the ground anchor
is locked off, grout the tendon inside a second sheath.

Where restressable ground anchors are used, provide a restressable
anchorage compatible with the post-tensioning system provided.

If multi-element tendons are used, properly seat the wedges as
recommended for the post-tensioning system provided.

**(e) Bearing plates**. Size the bearing plates so:

**(1)** The bending stresses in the plate do not exceed the yield
strength of the steel when a load equal to 95 percent of the minimum
specified ultimate tensile strength of the tendon is applied; and

**(2)** The average bearing stress of the bearing plate does not exceed
that recommended in section 3.1.7 of the PTI, *Guide Specification for
Post-Tensioning Materials.*

Weld trumpet to bearing plate. Make the inside diameter of the trumpet
equal to or larger than the hole in the bearing plate. Make the trumpet
long enough to accommodate movements during stressing and testing. For
multi-element tendons with encapsulation over the unbonded length, make
the trumpet long enough to enable the tendon to make a transition from
the diameter of the tendon in the unbonded length to the diameter of the
tendon at the anchorhead without damaging the encapsulation. Fill the
trumpet of restressable ground anchors with corrosion-inhibiting grease.
Provide a permanent Buna-N synthetic rubber seal or an approved equal
between the trumpet and the unbonded length corrosion protection.

Fill the trumpets of non-restressable ground anchors with grout. Provide
a 300‑millimeter minimum tightly-fitting temporary seal between the
trumpet and the unbonded length corrosion protection.

**256.06 Storing and Handling.** Handle and store tendons in a manner to
avoid damage or corrosion. Replace tendons exhibiting abrasions, cuts,
welds, weld splatter, corrosion or pitting. Repair or replace any
tendons exhibiting damage to encapsulation or sheathing. Degrease the
bond length of tendons, and remove solvent residue before installation.

**256.07 Installation.** Drill ground anchor holes within 300
millimeters of the required location. Drill the longitudinal axis of the
drill hole parallel to the longitudinal axis of the tendon. Install the
ground anchor within 3 degrees of the required inclination from
horizontal. Install the ground anchor with a horizontal angle within 3
degrees of a line drawn perpendicular to the plane of the structure. Do
not extend ground anchors beyond the right-of-way or easement limits.

Insert the tendon in the drill hole to the required depth without
driving or forcing. Where the tendon cannot be completely inserted,
remove the tendon, and clean or redrill the hole to permit insertion.

Use a positive displacement pump to grout tendons into drill holes using
either a neat cement grout or a sand/cement grout. Use a grout pump
equipped with a pressure gauge capable of measuring pressures of at
least 1 megapascal or twice the actual grout pressure, whichever is
greater. Use well-mixed grout that is free of lumps or other indications
of prior cement hydration. Continuously agitate the grout during
placement. Place the grout in one continuous operation.

Inject the grout from the lowest point of the drill hole. The grout may
be placed either before or after insertion of the tendon. Record the
quantity of the grout and the grout pressure for each ground anchor.
Control the grout pressures to avoid excessive heaving or fracturing.

Except as indicated below, the grout above the top of the bond length
may be placed at the same time as the bond length grout, but it shall
not be placed under pressure. Do not place grout at the top of the drill
hole in contact with the back of the structure or the bottom of the
trumpet.

If the ground anchor is installed in a fine-grained soil using drill
holes larger than 150 millimeters in diameter, place the grout above the
top of the bond length after the ground anchor has been tested and
stressed. The entire drill hole may be grouted at one time if it can be
demonstrated that the ground anchor does not derive a significant
portion of its load-carrying capacity from the soil above the bond
length.

Use pressure grouting for grout protected tendons anchored in rock.
After sealing the drill hole, pressure inject grout until a 0.3
megapascal grout pressure at the top of the drill hole is maintained for
5 minutes.

After grouting is complete, fill the grout tube with grout if it will
remain in the hole. Wait a minimum of 3 days before loading the tendon.

Extend the corrosion protection surrounding the unbonded length up
beyond the bottom seal of the trumpet or 300 millimeters into the
trumpet if no trumpet seal is provided.

Trim the corrosion protection surrounding the unbonded length of the
tendon as necessary so that it does not contact the bearing plate of the
anchorhead during testing and stressing.

Place the bearing plate and anchorhead so the axis of the tendon is
within 3 degrees of perpendicular to the bearing plate and the axis of
the tendon passes through the center of the bearing plate without
bending the tendon.

If grout protected tendons or fusion-bonded epoxy encapsulations are
used, electronically isolate the bearing plate, anchorhead, and trumpet
from the surrounding concrete, soldier pile, or any metallic element
embedded in the structure.

Place trumpet grease any time during construction. Place trumpet grout
after the ground anchor has been tested and stressed.

Completely cover all anchorages permanently exposed to the atmosphere
with a corrosion-inhibiting grease or grout.

**256.08 Testing and Stressing.** Test each ground anchor using a
maximum test load not to exceed 80 percent of the minimum ultimate
tensile strength of the tendon. Simultaneously apply the test load to
the entire tendon and all elements of multi-element tendons.

**(a) Testing equipment**. The testing equipment shall consist of:

**(1)** A dial gauge or vernier scale capable of measuring to 0.025
millimeter. Use a movement-measuring device having a minimum travel
equal to the theoretical elastic elongation of the total anchor length
at the maximum test load. Use a device with sufficient travel so the
anchor movement is measured without resetting the device.

**(2)** A hydraulic jack and pump. Use a jack and a calibrated pressure
gauge to measure the applied load. Have the jack and pressure gauge
calibrated as a unit by an independent firm within 45 days of the start
of ground anchor work. Use a pressure gauge graduated in 1 megapascal
increments or less. Use a jack having a minimum ram travel equal to the
theoretical elastic elongation of the total anchor length at the maximum
test load.

**(3)** A calibrated reference gauge. Have the reference gauge
calibrated with the test jack and pressure gauge. Keep it at the project
site.

**(b) Performance tests.** Place stressing equipment over the ground
anchor tendon so that the jack, bearing plates, load cells, and
stressing anchorage are axially aligned with the tendon and the tendon
is centered within the equipment.

Performance test 5 percent of the ground anchors or a minimum of
3 anchors, whichever is greater, at each separate structure. The CO will
select the ground anchors to be performance tested.

Perform the performance test as indicated in Table 256-1.

Raise the load from one increment to another immediately after recording
the ground anchor movement. Measure and record the ground anchor
movement to the nearest 0.025 millimeter with respect to an independent
fixed reference point at the alignment load and at each load increment.
Monitor the load with a pressure gauge. Place the reference pressure
gauge in series with the pressure gauge during each performance test. If
the load measured by the pressure gauge and the load measured by the
reference pressure gauge differ by more than 10 percent, recalibrate the
jack, pressure gauge, and reference pressure gauge. At load increments
other than the maximum test load, hold the load just long enough to
obtain the movement reading.

Table 256-1

Performance Test Load Sequence

+---------+---+------+------+------+------+------+------+------------+
| *       | * |      |      |      |      |      |      |            |
| *Test** | * |      |      |      |      |      |      |            |
|         | T |      |      |      |      |      |      |            |
| **Seq   | e |      |      |      |      |      |      |            |
| uence** | s |      |      |      |      |      |      |            |
|         | t |      |      |      |      |      |      |            |
|         | L |      |      |      |      |      |      |            |
|         | o |      |      |      |      |      |      |            |
|         | a |      |      |      |      |      |      |            |
|         | d |      |      |      |      |      |      |            |
|         | I |      |      |      |      |      |      |            |
|         | n |      |      |      |      |      |      |            |
|         | c |      |      |      |      |      |      |            |
|         | r |      |      |      |      |      |      |            |
|         | e |      |      |      |      |      |      |            |
|         | m |      |      |      |      |      |      |            |
|         | e |      |      |      |      |      |      |            |
|         | n |      |      |      |      |      |      |            |
|         | t |      |      |      |      |      |      |            |
|         | * |      |      |      |      |      |      |            |
|         | * |      |      |      |      |      |      |            |
+---------+---+------+------+------+------+------+------+------------+
|         | * | *    | *    | *    | *    | *    | *    | **Reduce   |
|         | * | *0.2 | *0.5 | *0.7 | *1.0 | *1.2 | *1.3 | to         |
|         | A | 5D** | 0D** | 5D** | 0D** | 0D** | 3D** | Lock-Off   |
|         | * |      |      |      |      |      |      | Load**     |
|         | * |      |      |      |      |      |      |            |
+---------+---+------+------+------+------+------+------+------------+
| 1       | * | *    |      |      |      |      |      |            |
|         | * | *•** |      |      |      |      |      |            |
|         | • |      |      |      |      |      |      |            |
|         | * |      |      |      |      |      |      |            |
|         | * |      |      |      |      |      |      |            |
+---------+---+------+------+------+------+------+------+------------+
| 2       | * | *    | *    |      |      |      |      |            |
|         | * | *•** | *•** |      |      |      |      |            |
|         | • |      |      |      |      |      |      |            |
|         | * |      |      |      |      |      |      |            |
|         | * |      |      |      |      |      |      |            |
+---------+---+------+------+------+------+------+------+------------+
| 3       | * | *    | *    | *    |      |      |      |            |
|         | * | *•** | *•** | *•** |      |      |      |            |
|         | • |      |      |      |      |      |      |            |
|         | * |      |      |      |      |      |      |            |
|         | * |      |      |      |      |      |      |            |
+---------+---+------+------+------+------+------+------+------------+
| 4       | * | *    | *    | *    | •    |      |      |            |
|         | * | *•** | *•** | *•** |      |      |      |            |
|         | • |      |      |      |      |      |      |            |
|         | * |      |      |      |      |      |      |            |
|         | * |      |      |      |      |      |      |            |
+---------+---+------+------+------+------+------+------+------------+
| 5       | * | *    | *    | *    | *    | *    |      |            |
|         | * | *•** | *•** | *•** | *•** | *•** |      |            |
|         | • |      |      |      |      |      |      |            |
|         | * |      |      |      |      |      |      |            |
|         | * |      |      |      |      |      |      |            |
+---------+---+------+------+------+------+------+------+------------+
| 6       | * | *    | *    | *    | *    | *    | *    | **•**      |
|         | * | *•** | *•** | *•** | *•** | *•** | *•** |            |
|         | • |      |      |      |      |      |      |            |
|         | * |      |      |      |      |      |      |            |
|         | * |      |      |      |      |      |      |            |
+---------+---+------+------+------+------+------+------+------------+

**Note:** A = Alignment load; D = Design load.

Hold the maximum test load for a minimum of 10 minutes. Repump the jack
as necessary in order to maintain a constant load. Begin the load-hold
period as soon as the maximum test load is applied.

Measure and record the ground anchor movement at 1, 2, 3, 4, 5, 6, and
10 minutes. If the ground anchor movement between 1 and 10 minutes
exceeds 1 millimeter, continue holding the maximum test load and record
ground anchor movement at 15, 20, 25, 30, 45, and 60 minutes.

Plot the ground anchor movement versus the maximum load for each test
sequence in Table 256-1, and plot the residual movement of the tendon at
each alignment load versus the highest previously applied load.

**(c) Proof tests**. Proof test all ground anchors that are not
performance tested. Perform the proof test as indicated in Table 256-2.

Raise the load from one increment to another immediately after recording
the ground anchor movement. Measure and record the ground anchor
movement to the nearest 0.025 millimeter with respect to an independent
fixed reference point at the alignment load, and at each load increment.
Monitor the load with a pressure gauge.

Hold the maximum test load for a minimum of 10 minutes. Repump the jack
as necessary in order to maintain a constant load. Begin the load-hold
period as soon as the maximum test load is applied.

Measure and record the ground anchor movement at 1, 2, 3, 4, 5, 6, and
10 minutes. If the anchor movement between 1 and 10 minutes exceeds 1
millimeter, continue holding the maximum test load and record anchor
movements at 15, 20, 25, 30, 45, and 60 minutes.

Table 256-2

Proof Test Load Sequence

+-----+--------+-------+------+-------+------+-------+--------------+
| **T |        |       |      |       |      |       |              |
| est |        |       |      |       |      |       |              |
| L   |        |       |      |       |      |       |              |
| oad |        |       |      |       |      |       |              |
| In  |        |       |      |       |      |       |              |
| cre |        |       |      |       |      |       |              |
| men |        |       |      |       |      |       |              |
| t** |        |       |      |       |      |       |              |
+-----+--------+-------+------+-------+------+-------+--------------+
| **  | **0    | **0.  | *    | **1.  | *    | **1.  | **Reduce     |
| A** | .25D** | 50D** | *0.7 | 00D** | *1.2 | 33D** | to**         |
|     |        |       | 5D** |       | 0D** |       |              |
|     |        |       |      |       |      |       | **Lock-Off** |
|     |        |       |      |       |      |       |              |
|     |        |       |      |       |      |       | **Load**     |
+-----+--------+-------+------+-------+------+-------+--------------+
| **  | **•**  | **•** | *    | **•** | *    | **•** | **•**        |
| •** |        |       | *•** |       | *•** |       |              |
+-----+--------+-------+------+-------+------+-------+--------------+

**Note:** A = Alignment load; D = Design load.

Plot the ground anchor movement versus load for each load increment in
Table 256-2.

**(d) Lock off.** Upon completion of performance and proof tests, reduce
the load to the specified lock-off load and transfer the load to the
anchorage device. After transferring the load and before removing the
jack, measure the lift-off load. If the load is not within 10 percent of
the specified lock-off load, reset the anchorage and remeasure the
lift-off load. Repeat as necessary.

**256.09 Acceptance.** See Table 256-3 for sampling and testing
requirements.

Material for ground anchors will be evaluated under Subsections 106.02
and 106.03.

Construction of ground anchors and services will be evaluated under
Subsections 106.02 and 106.04.

Grouting will be evaluated under Subsection 106.02 and 106.04.

Installed ground anchors will be evaluated based on one of the following
performance or proof test results:

**(a)** After a 10-minute hold, the ground anchor carries the maximum
test load with less than 1 millimeter of movement between 1 and 10
minutes and the total movement at the maximum test load exceeds 80
percent of the theoretical elastic elongation of the unbonded length.

**(b)** After a 60-minute hold, the ground anchor carries the maximum
test load with a creep rate that does not exceed 2-millimeter/log cycle
of time and the total movement at the maximum test load exceeds 80
percent of the theoretical elastic elongation of the unbonded length.

Replace all ground anchors with unacceptable performance or proof test
results. Do not retest failed ground anchors.

Measurement

**256.10** Measure the Section 256 items listed in the bid schedule
according to Subsection 109.02 and the following as applicable.

Measure performance tests that indicate acceptable installations.

Payment

**256.11** The accepted quantities will be paid at the contract price
per unit of measurement for the Section 256 pay items listed in the bid
schedule. Payment will be full compensation for the work prescribed in
this Section. See Subsection 109.05.

+----------+------------+-----------------+-----------+---------------+
| Table    | > *        | > Before        | > Before  | > "           |
| 256-3    | *Reporting | > producing     | >         |               |
|          | > Time**   |                 | producing |               |
| Sampling |            |                 |           |               |
| and      |            |                 |           |               |
| Testing  |            |                 |           |               |
| Requ     |            |                 |           |               |
| irements |            |                 |           |               |
+----------+------------+-----------------+-----------+---------------+
|          | > **Split  | > Yes           | > Yes,    | > "           |
|          | > Sample** |                 | > when    |               |
|          |            |                 | >         |               |
|          |            |                 | >         |               |
|          |            |                 | requested |               |
+----------+------------+-----------------+-----------+---------------+
|          | > **Point  | > Source of     | > Source  | > "           |
|          | > of**     | > material      | > of      |               |
|          | >          |                 | >         |               |
|          | > **       |                 |  material |               |
|          | Sampling** |                 |           |               |
+----------+------------+-----------------+-----------+---------------+
|          | > **       | > 1 per         | > 1 per   | > "           |
|          | Sampling** | > material type | > mix     |               |
|          |            |                 | > design  |               |
|          | **F        |                 |           |               |
|          | requency** |                 |           |               |
+----------+------------+-----------------+-----------+---------------+
|          | > **Test   | > AASHTO M 6    | > ASTM C  | > AASHTO T    |
|          | >          |                 | > 939     | > 106         |
|          |  Methods** |                 |           |               |
|          | >          |                 |           |               |
|          | > **Specif |                 |           |               |
|          | ications** |                 |           |               |
+----------+------------+-----------------+-----------+---------------+
|          | **         | > ---           | > ---     | > ---         |
|          | Category** |                 |           |               |
+----------+------------+-----------------+-----------+---------------+
|          | **Charac   | > Quality       | > Flow    | > 7-day       |
|          | teristic** |                 |           | >             |
|          |            |                 |           | > compressive |
|          |            |                 |           | >             |
|          |            |                 |           | > strength    |
+----------+------------+-----------------+-----------+---------------+
|          | **Type of  | Measured and    | Measured  |               |
|          | Ac         | tested          | and       |               |
|          | ceptance** |                 | tested    |               |
|          |            | for conformance |           |               |
|          | **(Sub     | (106.04)        | for       |               |
|          | section)** |                 | co        |               |
|          |            |                 | nformance |               |
|          |            |                 | (106.04)  |               |
+----------+------------+-----------------+-----------+---------------+
|          | > **       | > Aggregate     | > Grout   |               |
|          | Material** | >               | >         |               |
|          | >          | > source        | > mix     |               |
|          | > **or     | > quality       | > design  |               |
|          | >          | >               | >         |               |
|          |  Product** | > (fine)        | > (7      |               |
|          |            | >               | 22.02(e)) |               |
|          |            | > (703.01)      |           |               |
+----------+------------+-----------------+-----------+---------------+

## Section 257. --- ALTERNATE RETAINING WALLS

Description

**257.01** This work consists of constructing various types of retaining
walls at the Contractor\'s option. The alternate wall types are gabions,
crib walls, mechanically‑stabilized earth walls, permanent ground anchor
walls, and reinforced concrete retaining walls.

Material

**257.02** Conform to the following Sections:

Crib walls 254

Driven piles 551

Gabions 253

Mechanically-stabilized earth walls 255

Permanent ground anchors 256

Reinforced concrete retaining walls 258

Reinforcing steel 554

Structural concrete 552

Construction Requirements

**257.03 General.** The designer/supplier furnishing the proposed wall
is responsible for the stability of the wall. Do not qualify the
responsibility for the design or restrict the use of the drawings or
calculations for the proposed alternate. Indemnify the Government from
all claims for infringement of proprietary rights by others without the
consent of the patent holders or licensees.

**257.04 Submittal.** Submit a proposal using any of the wall types
listed. Submit wall type proposals on a site-by-site basis. Different
types may be used at individual sites on the project.

Survey according to Section 152, and verify the limits of the wall
installation. Provide drawings of the proposed wall according to
Subsection 104.03 within 120 days of the notice to proceed and at least
90 days before starting wall construction.

All drawings shall be signed by a professional engineer.

Include all details, dimensions, quantities, ground profiles, and
cross-sections necessary to construct the wall. Submit design
calculations on sheets about 200 by 300 millimeters in size with the
project number, wall location, designation, date of preparation,
initials of designer and checker, and page number at the top of the
page.

Provide an index page with the design calculations. The drawings must
include, but not be limited to, the following items:

**(a)** Plan and elevation drawings for each wall containing the
following:

**(1)** A plan view of the wall identifying:

*(a)* Offset from the construction centerline to the face of the wall at
its base at all changes in horizontal alignment;

*(b)* Limit of widest module, mesh, strip, or anchor; and

*(c)* Centerline of any drainage structure or drainage pipe behind,
passing through, or passing under the wall.

**(2)** An elevation view of the wall identifying:

*(a)* Elevation at the top of the wall, at all horizontal and vertical
break points, and at least every 10 meters along the wall;

*(b)* Elevations at the wall base, the top of leveling pads and
footings, or the bottom of soldier piles;

*(c)* Wall batter;

*(d)* Distance along the face of the wall to all steps in the wall base,
footings, leveling pads, or lagging;

*(e)* Type of panel or depth of module or lagging;

*(f)* Length and type of mesh, strips, or anchors;

*(g)* Distance along the face of the wall to where changes in length of
the mesh, strips, or anchors occur; and

*(h)* Original and final ground line.

**(3)** General notes for constructing the wall.

**(4)** Horizontal and vertical curve data affecting the wall. Match
lines or other details to relate wall stationing to centerline
stationing.

**(5)** A listing of the summary of quantities on the elevation drawing
of each wall.

**(b)** Dimensions and schedules of all reinforcing steel including
reinforcing bar bending details, dowels, and studs for attaching the
facing.

**(c)** Details and dimensions for foundations and leveling pads
including steps in the footings or leveling pads.

**(d)** Details and dimensions for all:

**(1)** Panels, modules, soldier piles, and lagging necessary to
construct the element;

**(2)** Reinforcing steel in the element;

**(3)** Location of mesh, strip attachment, or anchor devices embedded
in the panels; and

**(4)** Anchors and soldier piling including the spacing and size of
piles and the spacing and angle of anchors.

**(e)** Details for constructing walls around drainage facilities.

**(f)** Details for terminating walls and adjacent slope construction.

**(g)** Architectural treatment details.

**(h)** Design notes including an explanation of any symbols and
computer programs used in the design of the walls. Specify the factors
of safety for sliding, pullout, and overturning. Specify the bearing
pressure beneath the wall footing, stabilized earth mass, or soldier
piles.

**(i)** Verification of design criteria for the site specific wall
locations with test procedures, results, and interpretations. Include
results from creep, durability, construction induced damage, and
junction strength tests.

**(j)** Other design calculations.

Process all submissions through the Contractor unless the Contractor
gives written permission for the wall designer/supplier and the CO to
communicate directly.

Submit 3 sets of the wall drawings with the initial submission. One set
will be returned with any indicated corrections. If revisions are
necessary, make the necessary corrections and resubmit 3 revised sets.

When the drawings are accepted, furnish 5 sets and a mylar sepia set of
the drawings.

**257.05 Construction.** Construct the wall according to the accepted
drawings and the following Sections, as applicable:

**(a) Gabions**. Section 253.

**(b) Crib walls**. Section 254.

**(c)** **Mechanically-stabilized earth walls.** Section 255.

**(d)** **Permanent ground anchor walls**. Sections 256, 551, and 552.

**(e)** **Reinforced concrete retaining walls.** Section 258.

Revise the drawings when plan dimensions are revised due to field
conditions or for other reasons.

**257.06 Acceptance.** Material for alternate retaining walls will be
evaluated under Subsection 106.02, 106.03, or 106.04 according to the
applicable sections listed in Subsection 257.05.

Construction of alternate retaining walls and services will be evaluated
under Subsections 106.02 and 106.04 according to the applicable sections
listed in Subsection 257.05.

Structure excavation and backfill will be evaluated under Section 209.

Measurement

**257.07** Measure the Section 257 items listed in the bid schedule
according to Subsection 109.02 and the following as applicable.

Measure foundation fill under Section 208.

Payment

**257.08** The accepted quantities will be paid at the contract price
per unit of measurement for the Section 257 pay item listed in the bid
schedule. Payment will be full compensation for the work prescribed in
this Section. See Subsection 109.05.

When plan dimensions are changed by the CO during construction to
account for field conditions, the lump sum price of the wall will be
adjusted by applying a calculated per square meter cost adjustment
factor to the added or decreased wall front face area.

The adjustment factor will be determined by dividing the lump sum price
bid for each wall by its estimated area.

The alternate retaining wall lump sum will be paid based on the progress
of the work under this Section.

## Section 258. --- REINFORCED CONCRETE RETAINING WALLS

Description

**258.01** This work consists of constructing reinforced concrete
retaining walls.

Material

**258.02** Conform to the following Sections and Subsections:

Concrete 552

Forms and falsework 562

Joint fillers and sealants 712.01

Reinforcing steel 709.01

Structural backfill 704.04

Tie bars, dowel bars, and hook bolts 709.01

Construction Requirements

**258.03 General.** Survey according to Section 152, and verify the
limits of the wall installation. Prepare and submit forms and falsework
drawings according to Section 562. Perform the work under Section 209.

**258.04 Reinforcing Steel.** Submit all order lists and bending
diagrams according to Subsections 104.03 and 554.03. Fabricate
reinforcing steel according to Subsection 554.05. Ship and protect
material according to Subsections 554.04 and 554.06. Place, fasten, and
splice reinforcing steel according to Subsections 554.08 and 554.09.

**258.05 Structural Concrete.** Design concrete mixture according to
Subsection 552.03. Store, handle, batch, and mix material and deliver
concrete according to Subsections 552.04 through 552.08. Provide quality
control according to Section 153 and Subsection 552.09. Construct wall
according to Subsections 552.10 through 552.16.

**258.06 Backfilling.** Backfill the area behind the wall with
structural backfill according to Subsection 209.10. Compact each layer
according to Subsection 209.11 except use an approved lightweight
mechanical or vibratory compactor within one meter of the wall.

**258.07 Acceptance.** Reinforced concrete retaining wall material,
construction, and services will be evaluated as follows:

Survey work will be evaluated under Section 152.

Forms and falsework drawings will be evaluated under Section 562.

Structure excavation and backfill will be evaluated under Section 209.

Concrete will be evaluated under Section 552.

Reinforcing steel will be evaluated under Section 554.

Material for joint fillers, sealants, tie bars, dowel bars, and hook
bolts will be evaluated under Subsections 106.02 and 106.03.

Measurement

**258.08** Measure the Section 258 items listed in the bid schedule
according to Subsection 109.02 and the following as applicable.

Measure by the cubic meter of concrete in the structure including
footings.

Measure the square meter area by the length of the front wall face and
the height excluding footings.

Measure foundation fill under Section 208.

Payment

**258.09** The accepted quantities will be paid at the contract price
per unit of measurement adjusted according to Subsection 106.05 for the
Section 258 pay items listed in the bid schedule. Payment will be full
compensation for the work prescribed in this Section. See Subsection
109.05.

The accepted quantities of reinforced concrete retaining wall will be
paid for at the contract unit bid price multiplied by an adjusted pay
factor (*PFa*) determined as follows:

*PFa* = 1 ‑ 0.5 (1‑*PF*)

where:

*PF* = Pay factor for concrete as determined under Section 552.

## Section 259. --- SOIL NAIL RETAINING WALLS

Description

**259.01** This work consists of constructing soil nail retaining walls.

Material

**259.02** Conform to the following Section and Subsections:

Bolts and nuts 717.01(d)

Centralizers 722.02(f)

Geocomposite sheet drain 714.02(b)

Grout 722.02(e)

Shotcrete 566

Soil nails 722.04

Structural backfill 704.04

Structural steel (bearing plates) 717.01(a)

Welded stud sheer connectors 717.05

Construction Requirements

**259.03 Qualifications.** The Contractor or subcontractor must
demonstrate satisfactory completion of at least 5 permanent soil
nail-retaining wall projects during the past 3 years, totaling at least
1000 square meters of wall face area and at least 500 permanent soil
nails. Submit a brief description of each project including the owning
agency's name, contact person, and current telephone number.

Provide a professional engineer with experience in constructing at least
3 soil nail-retaining walls over the past 5 years. Provide on-site
supervisors and drill operators with experience installing permanent
soil nails on at least 3 projects over the past 5 years. At least 30
days before starting soil nail work, identify the engineer, on-site
supervisors, and drill operators assigned to the project and submit a
summary of each individual's experience.

**259.04 General.** Survey according to Section 152 and verify the
limits of the wall installation.

**259.05 Construction Plan.** At least 30 days before starting soil
nail-retaining wall work, submit the following according to Subsection
104.03:

**(a)** Start date and proposed retaining wall construction sequence.
Include the proposed method of excavating to ensure wall and slope
stability.

**(b)** Drilling methods and equipment. Include drill hole diameter to
achieve the specified pullout resistance values and any variation of
drill hole diameter or specific pullout resistance along the wall
alignment.

**(c)** Nail grout mix design, placement procedures, and equipment.
Include test results conducted according to AASHTO T 106 and supplied by
a qualified testing lab verifying grout 3-day and 28-day compressive
strengths. Previous test results for the same grout mix completed within
one year of grouting are acceptable.

**(d)** Soil nail testing methods and equipment setup.

**(e)** Identification number and calibration test results for each test
jack, pressure gauge, and load cell. Calibrate the test jack and
pressure gauge as one unit. Submit results from calibration tests
conducted by an independent testing laboratory within the previous 90
days.

**(f)** Ultimate strength of proposed soil nail tendons.

**259.06 Excavation.** Complete any clearing and excavation above the
wall area according to Sections 201 and 204 before commencing wall
excavation. Do not perform any of the wall excavation before beginning
the wall construction. A work bench for the drilling equipment may be
provided by placing material excavated from elsewhere on the project in
front of the soil nail wall area.

Perform excavation for the wall in lifts concurrent with soil nail
installation and shotcrete placement. Do not allow the exposed
unsupported final excavation face cut height to exceed the vertical nail
spacing plus the required reinforcing lap or the short-term stand-up
height of the ground, whichever is less. Complete excavation to the
final wall excavation line and application of the shotcrete in the same
work shift. Application of the shotcrete may be delayed up to 24 hours
if it can be demonstrated the delay will not adversely affect the
excavation face stability. A stabilizing berm of soil may be left in
place to contain the lift face during nail installation.

Do not excavate to the next lower lift until nail installation,
reinforced shotcrete placement, attachment of bearing plates and nuts,
and nail testing have been completed and accepted in the current lift.
Cure grout and shotcrete at least 72 hours or attain the specified 3-day
compressive strength before excavating the next underlying lift.

**259.07 Nail Installation.**

**(a) Storing and handling.** Store and handle soil nail tendons in a
manner that avoids damage or corrosion. Replace tendons exhibiting
abrasions, cuts, weld splatter, corrosion, or pitting. Repair or replace
any tendons exhibiting damage to the encapsulation or epoxy coating.

**(b) Fabrication.** Provide tendons threaded a minimum of 150
millimeters to allow proper attachment of bearing plate and nut.
Threading may be continuous spiral deformed ribbing provided by the bar
deformations or may be cut into the reinforcing bar. Use the next larger
bar size if threads are cut into the reinforcing bar. When appropriate,
repair damage to the epoxy coating with a minimum 0.3-mm-thick coating.

Provide centralizers sized to position the tendon within 25 millimeters
of the center of the drill hole. Position centralizers a maximum of 3
meters apart and within 600 millimeters from the top and bottom of the
tendon. Use centralizers that do not impede the free flow of grout into
the drill hole.

**(c) Drilling.** Drill holes for the soil nails at the locations and to
the orientation shown on the plans. Select drilling equipment and
methods suitable for the ground conditions. Do not use water, drilling
mud, or other fluids for drilling or removing cuttings. If unstable
ground is encountered, use cased drilling methods to support the
circumference of the drill holes. Self-drilling tendons are not
acceptable.

**(d) Grouting.** Insert the nail tendon into the hole and grout the
drill hole within 2 hours of completing drilling. Inject the grout at
the lowest point of each drill hole through a grout tube, casing,
hollow-stem auger, or drill rods. Completely fill the drill hole in one
continuous operation. To prevent voids, keep the outlet end of the grout
conduit below the surface of the grout as the conduit is withdrawn. Cold
joints in the grout column are only allowed at the top of the test bond
length of proof-tested production nails.

Maintain the temporary unbonded length of proof test nails open for
subsequent grouting. If the unbonded test length of production proof
test nails cannot be satisfactorily grouted subsequent to testing,
install a new nail in its place.

**259.08 Nail Testing.** Perform both verification and proof testing of
designated test nails. Do not test any nail until the nail grout and
shotcrete facing have cured for at least 72 hours and attained the
specified 3-day compressive strength.

**(a) Testing equipment.** Furnish two dial gauges, dial gauge support,
jack and pressure gauge, electronic load cell, and a reaction frame. The
load cell is required for verification tests only.

Use pressure gauges graduated in no greater than 500-kPa increments.
Measure the nail head movement with a minimum of two dial gauges capable
of measuring to 0.025 millimeters.

**(b) Verification test.** Perform verification tests on sacrificial
test nails at locations shown on the plans. Perform verification tests
before installation of production nails to verify drilling and
installation methods, nail pullout resistance, and design assumptions.

Provide verification test nails with both bonded and unbonded lengths.
The minimum unbonded length is 1 meter and the minimum bonded length is
3 meters. Determine the maximum bonded length based on the verification
nail bar grade and size to avoid exceeding the allowable bar structural
load during testing. Provide larger bar sizes if required to safely
accommodate the 3-meter minimum test bond length and testing to twice
the allowable pullout resistance.

Use the following formula to determine the maximum bonded length:

$$L_{\text{BV}_{\text{max}}}\  = \ \frac{\text{Cf}_{y}A_{s}}{2Q_{d}}$$

where:

L~BVmax~ = Maximum verification test nail bonded length (m)

C = 0.9 for grades 420 and 520 bars and 0.8 for grade 1035 bars

f~y~ = Bar yield or ultimate stress (kN/m^2^)

A~s~ = Bar steel area (m^2^)

Q~d~ = Allowable pullout resistance (kN/m)

Determine the design test load by the following equation:

$$\text{DTL}\  = \ L_{\text{BV}}\  \times \ Q_{d}$$

where:

DTL = Design test load (kN)

L~BV~ = As-built bonded test length (m)

Q~d~ = Allowable pullout resistance (kN/m)

Perform tests by incrementally loading the verification test nails as
indicated in Table 259-1. Measure and record soil nail movement at each
load increment.

The alignment load is the minimum load required to align the testing
apparatus and should not exceed 5 percent of the design test load. Set
dial gauges to "zero" after applying the alignment load. Following
application of the maximum load, reduce the load to the alignment load
and record the permanent set.

Hold each load increment for at least 10 minutes. Monitor the
verification test nail for creep at the 1.50 DTL load increment by
measuring and recording nail movement at 1, 2, 3, 5, 6, 10, 20, 30, 50,
and 60 minutes. Maintain the load during the creep test within 2 percent
of the intended load by use of the load cell.

Table 259-1

Verification Test Load Schedule

+-----------------------------------------+----------------------------+
| **Test Load Increment**                 | **Hold Time**              |
|                                         |                            |
|                                         | **(minutes)**              |
+-----------------------------------------+----------------------------+
| AL (0.05DTL max.)                       | 1                          |
+-----------------------------------------+----------------------------+
| 0.25DTL                                 | 10                         |
+-----------------------------------------+----------------------------+
| 0.50DTL                                 | 10                         |
+-----------------------------------------+----------------------------+
| 0.75DTL                                 | 10                         |
+-----------------------------------------+----------------------------+
| 1.00DTL                                 | 10                         |
+-----------------------------------------+----------------------------+
| 1.25DTL                                 | 10                         |
+-----------------------------------------+----------------------------+
| 1.50DTL (creep test)                    | 60                         |
+-----------------------------------------+----------------------------+
| 1.75DTL                                 | 10                         |
+-----------------------------------------+----------------------------+
| 2.00DTL (maximum load)                  | 10                         |
+-----------------------------------------+----------------------------+
| AL                                      | 1                          |
+-----------------------------------------+----------------------------+

**Note:** AL = Alignment load; DTL = Design test load.

**(c) Proof testing of production nails.** Perform proof tests on
production nails at locations selected by the CO. Perform successful
proof testing on 5 percent of the production nails in each nail row or a
minimum of 1 per row.

Provide production proof test nails with both bonded and temporary
unbonded lengths. The minimum temporary unbonded length is 1 meter.
Determine the maximum bonded length based on the production nail bar
grade and size to avoid exceeding the allowable bar structural load
during testing. Provide a test nail bonded length of 3 meters or
L~BPmax~, whichever is less.

Use the following formula to determine the maximum bonded length:

$$L_{\text{BP}_{\text{max}}}\  = \ \frac{\text{Cf}_{y}A_{s}}{1\text{.}5Q_{d}}$$

where:

L~BPmax~ = Maximum proof test nail bonded length (m)

C = 0.9 for grade 420 and 520 bars and 0.8 for grade 1035 bars

f~y~ = Bar yield or ultimate stress (kN/m^2^)

A~s~ = Bar steel area (m^2^)

Q~d~ = Allowable pullout resistance (kN/m)

Determine the design test load by the following equation:

$$\text{DTL}\  = \ L_{\text{BP}}\  \times \ Q_{d}$$

where:

DTL = Design test load (kN)

L~BP~ = As-built bonded test length (m)

Q~d~ = Allowable pullout resistance (kN/m)

Perform proof tests by incrementally loading the proof test nail to 150
percent of the design load as indicated in Table 259-2. Measure and
record soil nail movement at each load increment.

Table 259-2

Proof Test Load Schedule

+-------------------------------------------+---------------------------+
| **Test Load Increment**                   | **Hold Time**             |
|                                           |                           |
|                                           | **(minutes)**             |
+-------------------------------------------+---------------------------+
| AL (0.05DTL max.)                         | Until stable              |
+-------------------------------------------+---------------------------+
| 0.25DTL                                   | Until stable              |
+-------------------------------------------+---------------------------+
| 0.50DTL                                   | Until stable              |
+-------------------------------------------+---------------------------+
| 0.75DTL                                   | Until stable              |
+-------------------------------------------+---------------------------+
| 1.00DTL                                   | Until stable              |
+-------------------------------------------+---------------------------+
| 1.25DTL                                   | Until stable              |
+-------------------------------------------+---------------------------+
| 1.50DTL (maximum load)                    | See below                 |
+-------------------------------------------+---------------------------+

**Note:** AL = Alignment load; DTL = Design test load.

The alignment load should be the minimum load required to align the
testing apparatus and should not exceed 5 percent of the design test
load. Set dial gauges to "zero" after the alignment load has been
applied.

Perform either 10-minute or 60-minute creep tests at the maximum load.
Start the creep period after the maximum test load is applied. Measure
and record nail movement at 1, 2, 3, 5, 6, and 10 minutes. When the nail
movement between 1 minute and 10 minutes exceeds 1 millimeter, maintain
the maximum test load an additional 50 minutes, recording movement at
20, 30, 50, and 60 minutes. Maintain all load increments within 5
percent of the intended load.

**259.09 Wall Drainage Network.** Install drain strips, PVC connector
pipes, wall footing drains, and weepholes as shown on the plans.
Exclusive of the wall footing drains, install all elements of the
drainage network, as appropriate, before shotcreting each lift.

Install geocomposite sheet drain strips centered between nail columns
with the geotextile side against the ground. Add additional drain strips
at locations where seepage is obvious. Secure strips to the excavated
face to prevent shotcrete from contaminating the ground side of the
geotextile. Construct drain strip splices with a 300 millimeter overlap
so that the drain is vertically continuous and the splice does not
impede the flow of water. Install a drain plate and connector pipe at
the base of each strip.

Place PVC pipe sections, as required, to act as weepholes through the
construction shotcrete face.

Install footing drains at the bottom of the wall according to Section
605.

**259.10 Wall Construction.** Place steel welded wire mesh and
reinforcing steel according to Section 554.

Construct shotcrete facing according to Section 566. Completely fill the
top ungrouted zone of any nail drill holes or other voids with
shotcrete.

Attach a bearing plate and nut to each nail head. While the shotcrete is
still plastic, uniformly seat the plate by tightening the nut with a
hand wrench. Where uniform contact between the plate and the shotcrete
cannot be provided, set the plate in a bed of grout and tighten the nut
with a hand wrench after the grout has set for 24 hours.

Construction tolerances for wall elements are shown in Table 259-3.

Table 259-3

Wall Element Construction Tolerances

  --------------------------------------------------------- ---------------
  **Wall Element**                                          **Tolerance**

  Horizontal location of headed studs, from plan location   10 mm

  Location of headed studs on bearing plate, from plan      6 mm
  location                                                  

  Nail head bearing plate, deviation from parallel to wall  10 degrees
  face                                                      
  --------------------------------------------------------- ---------------

**259.11 Permanent Wall Facing.** Construct the permanent wall facing
according to the applicable Subsection below. When applicable, finish
surfaces with simulated stone masonry according to Section 613.

**(a) Shotcrete-faced walls.** Construct shotcrete facing according to
Section 566. Construction tolerances for the permanent shotcrete facing
are shown in Table 259-4.

**(b) Concrete-faced walls.** Construct according to Section 258.

Table 259-4

Permanent Shotcrete Facing Construction Tolerances

+--------------------------------------------------------+-------------+
| **Facing Finish**                                      | **          |
|                                                        | Tolerance** |
+--------------------------------------------------------+-------------+
| Complete thickness of shotcrete, from plan dimension:  | 15 mm       |
|                                                        |             |
| > Troweled or screeded finish                          | 30 mm       |
| >                                                      |             |
| > Shot finish                                          |             |
+--------------------------------------------------------+-------------+
| Planeness of finish face, surface gap under a 3-meter  | 15 mm       |
| straightedge:                                          |             |
|                                                        | 30 mm       |
| Troweled or screeded finish                            |             |
|                                                        |             |
| Shot finish                                            |             |
+--------------------------------------------------------+-------------+

**259.12 Backfilling Behind Wall Facing Upper Cantilever Section.**
Where the wall facing has an upper cantilever section, backfill with
structural backfill according to Subsection 209.10. Compact backfill
according to Subsection 209.11 within 1 meter behind this wall facing
section using light mechanical tampers.

**259.13 Acceptance.** Soil nail retaining wall material, construction,
and services will be evaluated as follows:

Survey work will be evaluated under Section 152.

Material for the soil nails will be evaluated under Subsections 106.03
and 106.04.

Construction of soil nails and services will be evaluated under
Subsections 106.02 and 106.04.

Installed soil nails will be evaluated based on the criteria in Table
259-5.

Table 259-5

Nail Acceptance Criteria

+-----------------+------------------+-----------------+--------------+
| **Type of Nail  | **Total Creep    | **Total         | **Pullout    |
| Test**          | Movement**       | Movement at     | Fai          |
|                 |                  | Maximum         | lure?^(3)^** |
|                 |                  | Load^(2)^**     |              |
+-----------------+------------------+-----------------+--------------+
| Verification    | \< 2mm between 6 | \>80%           | No           |
|                 | and 60           |                 |              |
|                 | minutes^(1)^     |                 |              |
+-----------------+------------------+-----------------+--------------+
| Proof           | \< 1mm between 1 | \>80%           | No           |
|                 | and 10 minutes,  |                 |              |
|                 | or               |                 |              |
|                 |                  |                 |              |
|                 | \< 2 mm between  |                 |              |
|                 | 6 and 60         |                 |              |
|                 | minutes^(1)^     |                 |              |
+-----------------+------------------+-----------------+--------------+

\(1\) And the creep rate is linear or decreasing throughout the creep
test load hold period.

\(2\) Percent of the theoretical elastic elongation of the test nail
unbonded length.

\(3\) Pullout failure is defined as the inability to further increase
the test load while there is continued pullout movement of the test
nail. Record the pullout failure load as part of the test data.

If a verification test fails, propose alternate installation methods
before installing additional verification test nails and install a
replacement verification test nail.

If a proof test fails, replace some or all of the installed production
nails between the failed proof test nail and the next proof test nail in
the row, as directed. Alternatively, install additional proof test nails
within this area to ensure that the acceptance criteria is being met
within this area. Propose alternative methods before installing
additional soil nails.

Measurement

**259.14** Measure the Section 259 items listed in the bid schedule
according to Subsection 109.02 and the following as applicable.

Measure soil nail retaining walls by the square meter of front wall
face.

Measure verification test nails by the each. Do not measure failed
verification test nails or additional verification test nails installed
to verify alternative nail installation methods proposed by the
Contractor.

Measure production soil nails by the meter. Measure along bar centerline
from the line of the wall excavation face to the tip of the nail.

Do not measure temporary stabilization berms.

Do not measure wall excavation.

Payment

**259.15** The accepted quantities will be paid for at the contract unit
price per unit of measurement for the Section 259 pay items listed in
the bid schedule. Payment will be full compensation for the work
prescribed in this Section. See Subsection 109.05.

+---------+--------+---------+---------+---------+---------+----------+
| Table   | >      | >       | >       | >       | >       | 30 days  |
| 259-6   |  **Rep |  Before |  Before |  Before |  Before | before   |
|         | orting | > using | > using | > using | > using | b        |
| S       | >      | > in    | > in    | > in    | > in    | eginning |
| ampling | Time** | > work  | > work  | > work  | > work  | soil     |
| and     |        |         |         |         |         | nail     |
| Testing |        |         |         |         |         | work     |
| Requi   |        |         |         |         |         |          |
| rements |        |         |         |         |         |          |
+---------+--------+---------+---------+---------+---------+----------+
|         | > *    | > ---   | > ---   | > ---   | > ---   | > ---    |
|         | *Split |         |         |         |         |          |
|         | > Sa   |         |         |         |         |          |
|         | mple** |         |         |         |         |          |
+---------+--------+---------+---------+---------+---------+----------+
|         | > *    | >       | >       | >       | >       | > ---    |
|         | *Point |  Source |  Source |  Source |  Source |          |
|         | > of** |         |         |         |         |          |
|         | >      |         |         |         |         |          |
|         | >      |         |         |         |         |          |
|         | **Samp |         |         |         |         |          |
|         | ling** |         |         |         |         |          |
+---------+--------+---------+---------+---------+---------+----------+
|         | >      | > Each  | > Each  | > Each  | > Each  | > 1 per  |
|         | **Samp | > s     | > s     | > s     | > s     | > source |
|         | ling** | hipment | hipment | hipment | hipment | >        |
|         |        |         |         |         |         | > of     |
|         | *      |         |         |         |         | >        |
|         | *Frequ |         |         |         |         | material |
|         | ency** |         |         |         |         |          |
+---------+--------+---------+---------+---------+---------+----------+
|         | >      | > Sub   | > Sub   | > Sub   | > Sub   | > Su     |
|         | **Test | section | section | section | section | bsection |
|         | > Met  | >       | >       | >       | >       | >        |
|         | hods** | > 72    | >       | > 72    | > 71    | > 259.05 |
|         | >      | 2.02(f) |  722.04 | 2.04(c) | 4.02(b) |          |
|         | >      |         |         |         |         |          |
|         | **Spec |         |         |         |         |          |
|         | ificat |         |         |         |         |          |
|         | ions** |         |         |         |         |          |
+---------+--------+---------+---------+---------+---------+----------+
|         | **Cate | > ---   | > ---   | > ---   | > ---   | > ---    |
|         | gory** |         |         |         |         |          |
+---------+--------+---------+---------+---------+---------+----------+
|         | **Char | >       | >       | >       | >       | >        |
|         | acteri | Quality | Quality | Quality | Quality |  Quality |
|         | stic** | > &     | > &     | > &     | > &     | > &      |
|         |        | > perf  | > perf  | > perf  | > perf  | >        |
|         |        | ormance | ormance | ormance | ormance | strength |
+---------+--------+---------+---------+---------+---------+----------+
|         | **Type | Certif  | Certif  | Certif  | Certif  | Certi    |
|         | of     | ication | ication | ication | ication | fication |
|         | Accept | of      | of      | of      | of      | of       |
|         | ance** | com     | com     | com     | com     | co       |
|         |        | pliance | pliance | pliance | pliance | mpliance |
|         | **(S   |         |         |         |         |          |
|         | ubsect | (       | (       | (       | (       | (106.03) |
|         | ion)** | 106.03) | 106.03) | 106.03) | 106.03) |          |
+---------+--------+---------+---------+---------+---------+----------+
|         | > **Ma | > Centr | > Soil  | > Epoxy | > Geoco | > Grout  |
|         | terial | alizers | > nails | >       | mposite | > mix    |
|         | > or   |         |         | coating | > sheet | > design |
|         | > Pro  |         |         |         | > drain |          |
|         | duct** |         |         |         |         |          |
+---------+--------+---------+---------+---------+---------+----------+

+---------+-------+---------+---------+---------+---------+---------+
| Table   | > *   | 30 days | > ---   | > ---   | > ---   | > ---   |
| 259-6   | *Repo | before  |         |         |         |         |
| (con    | rting | be      |         |         |         |         |
| tinued) | > T   | ginning |         |         |         |         |
|         | ime** | soil    |         |         |         |         |
| S       |       | nail    |         |         |         |         |
| ampling |       | work    |         |         |         |         |
| and     |       |         |         |         |         |         |
| Testing |       |         |         |         |         |         |
| Requi   |       |         |         |         |         |         |
| rements |       |         |         |         |         |         |
+---------+-------+---------+---------+---------+---------+---------+
|         | > **  | > ---   | > ---   | > ---   | > ---   | > ---   |
|         | Split |         |         |         |         |         |
|         | > Sam |         |         |         |         |         |
|         | ple** |         |         |         |         |         |
+---------+-------+---------+---------+---------+---------+---------+
|         | > **  | > Mixer | > Insta | > Insta | > Insta | > Insta |
|         | Point |         | llation | llation | llation | llation |
|         | >     |         |         |         |         |         |
|         |  of** |         |         |         |         |         |
|         | >     |         |         |         |         |         |
|         | > **  |         |         |         |         |         |
|         | Sampl |         |         |         |         |         |
|         | ing** |         |         |         |         |         |
+---------+-------+---------+---------+---------+---------+---------+
|         | > **  | > 1 per | > Each  | > Each  | > ---   | > ---   |
|         | Sampl | > mix   | > verif | > proof |         |         |
|         | ing** | >       | ication | > nail  |         |         |
|         |       |  design | > nail  |         |         |         |
|         | **F   |         |         |         |         |         |
|         | reque |         |         |         |         |         |
|         | ncy** |         |         |         |         |         |
+---------+-------+---------+---------+---------+---------+---------+
|         | > *   | > Sub   | > Sub   | > Sub   | > Table | > Table |
|         | *Test | section | section | section | > 259-3 | > 259-4 |
|         | >     | >       | >       | >       |         |         |
|         |  Meth | > 72    | > 25    | > 25    |         |         |
|         | ods** | 2.02(e) | 9.08(b) | 9.08(c) |         |         |
|         | >     | >       | >       | >       |         |         |
|         | > **S | >       | > Table | > Table |         |         |
|         | pecif |  AASHTO | > 259-5 | > 259-5 |         |         |
|         | icati | > T 106 |         |         |         |         |
|         | ons** |         |         |         |         |         |
+---------+-------+---------+---------+---------+---------+---------+
|         | **    | > ---   | > ---   | > ---   | > ---   | > ---   |
|         | Categ |         |         |         |         |         |
|         | ory** |         |         |         |         |         |
+---------+-------+---------+---------+---------+---------+---------+
|         | **C   | > Comp  | > Perf  | > Perf  | > Insta | > Pl    |
|         | harac | ressive | ormance | ormance | llation | acement |
|         | teris | > s     |         |         |         |         |
|         | tic** | trength |         |         |         |         |
+---------+-------+---------+---------+---------+---------+---------+
|         | *     | M       | M       | M       | M       | M       |
|         | *Type | easured | easured | easured | easured | easured |
|         | of    | and     | and     | and     | and     | and     |
|         | Ac    | tested  | tested  | tested  | tested  | tested  |
|         | cepta |         |         |         |         |         |
|         | nce** | for     | for     | for     | for     | for     |
|         |       | conf    | conf    | conf    | conf    | conf    |
|         | *     | ormance | ormance | ormance | ormance | ormance |
|         | *(Sub | (       | (       | (       | (       | (       |
|         | secti | 106.04) | 106.04) | 106.04) | 106.04) | 106.04) |
|         | on)** |         |         |         |         |         |
+---------+-------+---------+---------+---------+---------+---------+
|         | >     | > Nail  | > Verif | > Proof | > Wall  | > Pe    |
|         | **Mat | > grout | ication | > test  | > e     | rmanent |
|         | erial |         | > test  | > nail  | lements | > sh    |
|         | > or  |         | > nail  |         |         | otcrete |
|         | >     |         |         |         |         | >       |
|         |  Prod |         |         |         |         |  facing |
|         | uct** |         |         |         |         |         |
+---------+-------+---------+---------+---------+---------+---------+

## Section 260. --- ROCK BOLTS

Description

**260.01** This work consists of furnishing and installing tensioned
rock bolts.

Material

**260.02** Conform to the following Subsections:

Grout 722.02(e)

Rock Bolts 722.03

Construction Requirements

**260.03 Submittal.** At least 14 days before the installation of rock
bolts, submit the following information:

**(a)** Evidence that the foreman has a minimum of 1500 hours and the
drill operator has a minimum of 1000 hours of satisfactory work in
similar installation of post-tensioned rock bolts.

**(b)** Construction sequence and schedule.

**(c)** Drilling methods and type of equipment.

**(d)** Proposed rock bolt, couplers, bearing plate, anchor unit, flat
washer, and beveled washer specifications including manufacturer's data
sheets and specifications for any additional hardware items.

**(e)** If using cartridged polyester-resin adhesives, include
manufacturer's data sheets and placement procedures.

**(f)** Proposed grout mix design.

**(g)** Calibration data for each torque wrench to be used. Submit
results of calibration test performed by an independent testing
laboratory within the last 60 days.

Allow 7 days for acceptance or rejection. Do not begin work until
submittals have been approved.

**260.04 Rock Bolt.** Size the bolt so the design load does not exceed
60 percent of the minimum guaranteed ultimate tensile strength of the
bolt. Select and fabricate bolts to carry the specified loads.

Couple only grouted bolts. Couple sections together when standard,
commercially-available lengths are exceeded. Provide a center stop for
connecting sections so that an equal length of thread connects each
section. Provide couplings that equal the manufacturer's guaranteed
ultimate strength for the rock bolt. Do not fabricate couplings in a
manner that interferes with the flow of grout.

**260.05 Handling and Storage.** Protect bolts from dirt, mud, water,
and other harmful substances to avoid damage and corrosion. Do not use
rock bolts that are heavily corroded, pitted, damaged due to welding, or
show signs of abrasions, cuts, or nicks.

**260.06 Installation.** Drill holes at the locations and orientations
shown in the plans or as directed by the CO and to the diameter
specified by the bolt manufacturer. Clean holes of all drill cuttings,
sludge, and debris before the rock bolt is inserted or grout is injected
into the hole. Insert bolt into the hole. Attach the bearing plate,
washer, and nut to the bolt with the threaded outer end of the bolt
projecting beyond the nut at least 50 millimeters.

For grout-anchored bolts, inject sufficient grout into the drill hole to
fill the bond zone around the bolt. Apply tension to bolt after the time
specified in Table 260-1.

Table 260-1

Grout Curing Time

+-------------------------------------+--------------------------------+
| **Cement Type**                     | **Curing Time**                |
|                                     |                                |
|                                     | **(Days)**                     |
+-------------------------------------+--------------------------------+
| I                                   | 5                              |
+-------------------------------------+--------------------------------+
| II                                  | 5                              |
+-------------------------------------+--------------------------------+
| III                                 | 3                              |
+-------------------------------------+--------------------------------+

For bolts anchored with polyester resin, use fast-setting polyester
resin cartridges in the bond zone and slow-setting polyester resin
cartridges in the no load zone with gel times consistent with rapid
installation. Select cartridge diameters in accordance with the
manufacturer's recommendations to ensure complete encapsulation of the
rock bolt and satisfactory in-hole mixing. Break and mix resin
cartridges by spinning the bolt as it is inserted into the drill hole
according to the manufacturer's instructions.

For mechanically-anchored, hollow-stem rock bolts, tension the bolt
before grouting. After grouting, inject grout through the hollow core of
the bolt or through a grout tube until the space between the bolt and
drill hole wall is filled and grout is forced out of the de-airing tube
at the face of the hole.

**260.07 Tensioning.** Apply tension to the bolt with a calibrated
torque wrench to 125 percent of the design load. After tensioning, lock
bolt off at the specified design load.

Tension polyester resin-anchored bolts immediately after the fast-set
resin in the bond zone has set up and before the slow-set resin in the
unbonded zone has set up.

Tension grouted bolts after the bonded length has been grouted and the
grout has set up but before the unbonded length is grouted.

Tension mechanically-anchored rock bolts immediately after insertion
into the drill hole according to the manufacturer's recommendations.

Allow the bolt to remain in place if:

**(a)** The bolt can be tensioned to 125 percent of the design load and
the load can be held for 10 minutes.

**(b)** The design load is maintained after final grouting has been
accomplished.

Replace any bolt that does not meet (a) or (b) in a manner and in a
location approved by the CO.

**260.08 Acceptance.** Material for rock bolts will be evaluated under
Subsection 106.02 and 106.03.

Installation of rock bolts will be evaluated under Subsections 106.02
and 106.04.

Measurement

**260.09** Measure the Section 260 items listed in the bid schedule
according to Subsection 109.02.

Payment

**260.10** The accepted quantities will be paid at the contract price
per unit of measurement for the Section 260 pay items listed in the bid
schedule. Payment will be full compensation for the work prescribed in
this Section. See Subsection 109.05.

## Section 261. --- ROCK DOWELS

Description

**261.01** This work consists of furnishing and installing rock dowels.

Material

**261.02 Materials.** Conform to the following Sections and Subsections:

Concrete 601

Grout 722.02(e)

Reinforcing steel 709.01(b)

Shotcrete 566

Supply reinforcing steel for dowels in the form of deformed or threaded
bar.

Construction Requirements

**261.03 General.** Install dowels at the locations and to the depths
shown on the plans or directed by the CO.

**261.04 Drilling.** Drill holes for dowels perpendicular to the
supporting rock surface and as close as possible to the rock that is to
be supported. Drill holes for rock dowels a minimum of 25 millimeters
larger than the dowel diameter.

**261.05 Installation.** Partially fill the dowel hole with grout. Place
and center the dowel in the drill hole. Inject sufficient grout to fill
the remainder of the hole. Encase the length of dowel protruding from
the hole with a sufficient amount of shotcrete or hand-packed concrete
to completely encapsulate the dowel and fill the space between the dowel
and the surface of the rock to be supported. Construct forms as
necessary to contain the shotcrete or concrete until it has hardened.

**261.06 Acceptance.** Material for dowels will be evaluated under
Subsections 106.02 and 106.03.

Installation of rock dowels will be evaluated under Subsections 106.02
and 106.04.

Measurement

**261.07** Measure the Section 261 items listed in the bid schedule
according to Subsection 109.02.

Payment

**261.08** The accepted quantities will be paid at the contract price
per unit of measurement for the Section 261 pay items listed in the bid
schedule. Payment will be full compensation for the work prescribed in
this Section. See Subsection 109.05.