02731_-_Manhole_Lining.pdf

Sewer Manhole Rehabilitation Project 02731-1 Project No. 07693 City of Hayward Manhole Lining November 2025

SECTION 02731

MANHOLE LINING

PART 1 - GENERAL

1.01 GENERAL

A. This section defines the methods and materials for providing a mortar and epoxy composite corrosion barrier system (lining) for protection of sanitary sewer manholes and other sanitary sewer structures.

B. Related Sections

03300 Cast-in-Place Structural Concrete

1.02 REFERENCES

A. ACI 305R – Hot Weather Concreting

B. ASTM C109 – Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or 50-mm Cube Specimens)

C. ASTM C293 – Standard Test Method for Flexural Strength of Concrete (Using Simple Beam With Center-Point Loading)

D. ASTM C496 – Standard Test Method for Splitting Tensile Strength of Cylindrical Concrete Specimens

E. ASTM C596 – Standard Test Method for Drying Shrinkage of Mortar Containing Hydraulic Cement

F. ASTM C882 – Standard Test Method for Bond Strength of Epoxy-Resin Systems Used with Concrete By Slant Shear

G. International Concrete Repair Institute (ICRI) Technical Guideline No. 03730 – Surface Preparation Guidelines for the Repair of Deteriorated Concrete Resulting From Reinforcing Steel Corrosion

H. National Association of Corrosion Engineers International, NACE RP 0188 – Discontinuity (Holiday) Testing of Protective Coatings

1.03 DEFINITIONS

A. “Contractor” includes the general contractor in direct contract with the owner, subcontractor, or any tradesman responsible for construction.

B. “Owner’s Representative” or “City’s Representative” includes the Inspector, Engineer of Record, or Construction Manager representing the owner’s or City’s interests, and not directly compensated by the Contractor.

C. “Cold Weather” is defined as a period when, for more than 3 consecutive days, the following conditions exist:

1. Average daily air temperature is less than 40 F degrees (5 C) and

2. Air temperature is not greater than 50 F degrees (10 C) for more than one-half of any 24-hour period.

Sewer Manhole Rehabilitation Project 02731-2 Project No. 07693

D. “Hot weather” is defined by any one of the following conditions:

1. Ambient air temperature above 90 F degrees (32 C).

E. “Mass Concrete” refers to single pour cast-in-place concrete that is greater than 2’-10” thick, or is 2’-6” thick or greater, with an area larger than 500 square feet.

1.04 QUALIFICATION OF WORK CREW

A. The lining material Manufacturer shall maintain a listing of competent contractors that have demonstrated requisite skill and training to be qualified applicators of their materials.

B. Prior to project commencement, the Contractor must show to the satisfaction of the City’s Representative that all Contractor’s work crew personnel have performed satisfactory work in similar capacities elsewhere for a sufficient period of time to be fully qualified to properly perform the work in accordance with the requirements of the related specifications.

C. Foreman shall have at least 4 years experience with similar work and project conditions.

D. Nozzlemen shall be qualified by having had similar work experience.

1.05 SUBMITTALS

A. The Contractor shall furnish detailed and complete data pertaining to the surfaces of the structure to be rehabilitated, the rehabilitation product, surface preparation and installation to the engineer for approval. The submission of this data shall be made in a timely manner to prevent project delay. At the request of the City’s Representative, the Contractor shall test for adverse chemical conditions that may hinder overall product performance.

B. Prior to initiating the work, the Contractor shall submit specific technical data with complete physical properties of the structure to be rehabilitated and the proposed product for the rehabilitation of the structure, as well as a specific plan for sub-surface preparation.

C. Contractor shall submit a work plan 48 hours prior to beginning lining work. Work plan shall include provisions for curing and testing.

D. Contractor shall submit a safety plan 48 hours prior to beginning lining work. It is the contractor's responsibility to comply with OSHA standards and all regulations pertaining to the work including confined space entry.

E. Contractor shall submit qualifications for foreman and nozzleman(men) demonstrating work experience and certification of competency from material manufacturer.

PART 2 - PRODUCTS

2.01 GENERAL

A. Restoration mortar and epoxy corrosion barrier shall be from a single manufacturer.

B. All materials shall be compatible with the substrate and with each other.

C. Restoration mortar and epoxy corrosion barrier system shall have a minimum three years successful service history in aggressive sewer environments.

Sewer Manhole Rehabilitation Project 02731-3 Project No. 07693

2.02 RESTORATION MORTAR

A. Restoration mortar shall be a low shrinkage, high strength, polymer modified, sprayable microsilica mortar.

1. Mortar shall not contain calcium aluminate cements or aggregates.

2. Mortar shall have compressive strength per ASTM C109 of:

a. 24 hours: 3,000 psi

b. 28 days: 10,000 psi

3. Mortar shall achieve flexural strength per ASTM C293 of:

a. 24 hours: 535 psi

b. 28 days: 1,400 psi

4. Mortar shall achieve tensile strength per ASTM C496 of:

a. 24 hours: 330 psi

b. 28 days: 790 psi

5. Mortar shall have 28-day shrinkage of zero (0) as measured by ASTM C596.

6. Mortar shall have 28-day bond strength of 3,440 psi as measured by ASTM C882.

7. Mortar shall be Mainstay ML-72 Sprayable Microsilica Restoration Mortar or approved equal.

2.03 EPOXY CORROSION BARRIER

A. Epoxy corrosion barrier shall be a 100% solids, two-component, sprayable, high-build coating that is formulated for use in wastewater environments with a pH of 0.5 or higher.

1. Epoxy shall be formulated to be applied in a single coat with minimum thickness of 100 mils.

2. Epoxy shall have a smooth, glossy finish.

3. Epoxy color shall be off-white or other light color as approved by City.

4. Epoxy corrosion barrier shall be Mainstay DS-5 100% Solids Epoxy Coating or approved equal.

2.04 HYDRAULIC CEMENT MORTAR

A. Hydraulic cement mortar shall be used to plug leaks in the structure prior to application of coating.

B. Hydraulic cement mortar shall be a fast-setting blend of hydraulic cement and fillers formulated to stop leaks through cracks and holes concrete and brick/mortar structures.

Working time shall be a minimum of 45 seconds at 77 degrees Fahrenheit.

C. Hydraulic cement mortar shall be compatible with substrate and with restoration mortar.

D. Hydraulic cement mortar shall be Mainstay ML-10 Hydraulic Cement Mortar, or other product recommended by the manufacturer of the restoration mortar that is approved by the City.

Sewer Manhole Rehabilitation Project 02731-4 Project No. 07693

E. Injectable polymer gel or foam may be used in conjunction with hydraulic cement mortar to stop significant leakage. The gel or foam shall be approved for use with the hydraulic cement mortar as approved by the manufacturer of the hydraulic cement mortar.

2.05 EQUIPMENT

A. Equipment shall be of spray type and approved by the material manufacturer. Alternate equipment may be utilized provided it meets the performance requirements of the specification. All equipment must be kept in operating condition and good repair.

PART 3 - EXECUTION

3.01 DELIVERY, STORAGE, AND HANDLING

A. All materials shall be delivered to the site in the manufacturer’s original, unopened containers and packaging with labels clearly identifying product name and manufacturer.

B. All materials shall be stored in accordance with manufacturer’s recommendations. All containers shall be kept sealed until ready for use. All material shall be kept in a cool, dry environment.

C. All materials shall be protected during transport, handling, and application to prevent damage.

3.02 EXAMINATION

A. All surfaces shall be examined by the Contractor and the City’s Representative prior to beginning work. Do not begin surface preparation or application until unacceptable conditions have been corrected.

3.03 SURFACE PREPARATION

A. Prepare surfaces in accordance with manufacturer’s instructions.

B. Clean all surfaces by low pressure water cleaning (4,000 psi minimum), by abrasive blasting, by hand, and/or with power tools to remove all unsound concrete, contaminants, dirt, debris, and deteriorated reinforcing steel. Prepared surfaces shall have a minimum ICRI Concrete Surface Profile (CSP) #4 (preferably with aggregate exposed).

C. Inspect all cleaned surfaces to identify and mark corroded reinforcing steel and to locate cracks, leaks, and joints.

D. Replace or treat corroded reinforcing steel, repair cracks and leaks, and treat joints in accordance with manufacturer’s instructions and as approved by City’s Representative.

E. All surfaces shall be moistened with clean water prior to application as recommended by the manufacturer.

3.04 ENVIRONMENTAL CONDITIONS

A. Do not apply materials under the following conditions:

1. Temperatures above or below the manufacturer’s recommended maximum or minimum allowable temperatures.

2. In dusty or smoke-laden atmospheres.

Sewer Manhole Rehabilitation Project 02731-5 Project No. 07693

3. If any overflowing water or leakage is present.

3.05 APPLICATION OF RESTORATION MORTAR

A. Application of restoration mortar shall commence as soon as surface moisture conditions meet manufacturer’s recommendations.

B. Restoration mortar shall be applied using low to medium velocity wet mix shotcrete application, by hand trowel, or by approved centrifugal applicator.

C. Restoration mortar shall be applied uniformly to all surfaces to be coated.

D. Apply in such a manner as to avoid trapping air in corners, behind exposed reinforcing steel, or between lifts.

E. Restoration mortar shall be applied to a minimum thickness of ½ inch above peaks of existing surface profile after surface preparation.

F. Smooth the applied restoration mortar using a steel trowel with rounded ends (a “pool trowel”) and finish with a sponge or brush to produce a smooth, lightly textured surface upon which to apply the corrosion barrier.

3.06 APPLICATION OF EPOXY CORROSION BARRIER

A. Application of epoxy corrosion barrier shall commence as soon as the restoration mortar has suitably cured in accordance with manufacturer’s recommendations.

B. Do not allow any contamination of the surface of the restoration mortar prior to application of the epoxy corrosion barrier.

C. Apply the epoxy corrosion barrier to a uniform thickness using spray applicator. Thickness shall be 100 mils, minimum.

3.07 CURING OF EPOXY CORROSION BARRIER

A. Protect the epoxy corrosion barrier from liquids, cold temperatures, contaminants, and surface contact until the epoxy has achieved a hard, tack-free condition.

3.08 FIELD QUALITY CONTROL

A. Perform a visual inspection of all surfaces to look for holidays, air pockets, unwanted inclusions, and other defects. Mark such areas for repair and reapplication of epoxy corrosion barrier.

B. Perform a high voltage holiday detection test in accordance with NACE RP 0188. Exercise caution when performing high voltage holiday testing in damp and/or potentially explosive environments.

C. Repair all defects in accordance with manufacturer’s recommendations. Perform follow-up visual and high voltage holiday detection tests to confirm suitability of repairs.

**END OF SECTION**

Sewer Manhole Rehabilitation Project 02731-6 Project No. 07693

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