24-8250_Exhibit_J_-_Special_Specification_Imper._Liner.pdf

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SPECIAL SPECIFICATION

Impermeable Liner

1. Description. This Item shall govern for the furnishing and installation of the impermeable liner (geomembrane) shown on the plans. The geomembrane shall be high density polyethylene (HDPE) membrane used to prevent contaminants from entering the newly constructed storm system. The geomembrane shall be capable of preventing the migration of hazardous products from the soils and groundwater within the contaminated areas. The geomembrane shall serve as a barrier to groundwater and soil vapor at these impacted locations. The geomembrane shall minimize the migration of contaminated soil vapor into the manholes at the “special” manhole locations. A protective engineering fabric (geotextile) shall be installed on top of the geomembrane to protect the geomembrane during backfilling operations. The HDPE membrane shall be used in the designated areas, as shown on the plans.

2. Materials.

(1) Geomembrane.

(a) The geomembrane liner shall be new and comprised of HDPE material manufactured of first-quality products designed and manufactured specifically for the purpose of liquid containment in hydraulic structures. The nominal thickness of the HDPE membrane shall be 30 mils.

(b) The Contractor shall, at the time of award, submit to the Engineer, a certification from the manufacturer of the sheeting, stating that the sheeting meets physical property requirements for the intended application.

(c) The surface of the geomembrane shall not have striation, roughness, pinholes or bubbles and shall be so produced to be free of holes, blisters, undispersed raw materials, or any sign of contamination by foreign matter. Any defects shall be reported to the Engineer immediately after discovery and replaced or repaired under the direction of the Engineer at the Contractor's expense. If repair is required, extrusion fusion welding technique shall be performed in accordance with the manufacturer's recommendations.

(d) The geomembrane shall be manufactured in a minimum of 25 ft. seamless widths.

Labels on the roll shall identify the thickness, length, width and manufacturer's batch and roll number. There shall be no factory seams.

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(e) The geomembrane rolls shall meet the minimum values shown in the following chart:

Geomembrane Specifications *

Property Value Test Method Nominal Thk 30 mils

Density (Min) 0.940 g/cc

ASTM D1505

Melt Flow Index (Max) 0.40 g/10 min

ASTM D1238 Condition E (190 C, 2.16 kg)

Tensile Properties (Typical)

ASTM D 638 Type IV Dumb-bell at 5.1 cm/min

Tensile Strength at Break 28.6 (kg/cm width)

Tensile Strength at Yield 16.4 (kg/cm width)

Elongation at Break 750 %

Elongation at Yield 13 %

Tear Resistance Initiation (Typical)

12.7 kg ASTM D1004 Die C

Low Temperature Brittleness (Typical)

-70 (deg C)

ASTM D746

Procedure B

Dimensional Stability Change Each Direction (Max)

+/- 1 % ASTM D1204

100 C, 1 hr.

Environmental Stress Crack. (Min)

2,000 Hours

ASTM D1693

(10% Igepal, 60 C)

Puncture Resistance (Typical)

27 kg FTMS 101 Method 2065

Coefficient of Linear Thermal Expansion (Typical)

0.0002 cm/cm C

ASTM D696

Thermal Stability Oxidative Induction Time (OIT)

2,000 Minutes

ASTM D3895

130 C, 5516 KPa Oxygen (Min) Carbon Black 2 - 3 %

* Note: Minimum values, unless otherwise specified, are the average roll values as reported by the specified test methods.

(f) Raw Material. All compound ingredients of the HDPE materials shall be randomly sampled on delivery to the HDPE manufacturing plant to ensure compliance with the required specifications. Tests to be carried out shall include Density ASTM D1505 and Melt Index ASTM D1238, Condition E.

(g) Manufactured Roll Goods. Samples of the production run shall be taken and tested according to ASTM D638 to ensure that tensile strength at yield and break, and elongation at yield and break meet the minimum specifications. A quality control certificate shall be issued with the material.

(h) All welding material shall be of a type recommended by the manufacturer.

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(2) Geotextile:

(a) The new geotextile shall be manufactured from polyester, polypropylene, or polypropylene - nylon material. The fabric shall be non-woven.

(b) The Contractor shall, at the time of award, submit a certificate to the Engineer, from the manufacturer of the geotextile, stating the geotextile meets the physical property requirements for the intended application.

(c) The geotextile shall be of uniform thickness and surface texture, and conform to the following types as shown on the plans:

Property Value Test Method Type I Geotextile

Weight, nominal 190 G/sq meter

ASTM D 3776

Thickness, min. 80 mils ASTM D 1777 Grab Tensile Strength (25 millimeter grip), min.

91 KG ASTM D 4632

Elongation at break, min. 50% ASTM D 4632 UV resistance, 500 hrs. 85%

Strength retention

ASTM D 4355

(d) The geotextile shall be furnished in protective covers capable of protecting the fabric from ultraviolet rays, abrasion and water.

(e) The geotextile shall not be installed or exposed to the ultraviolet rays more than 20 days prior to the installation of storm sewer and backfill operations.

3. Construction Methods: The liner method system shall consist of a layer of protective geotextile over a layer of 30 mil HDPE geomembrane.

The Engineer reserves the right to inspect the manufacturer's or the fabricator's facilities to ensure compliance with these specifications.

(1) Area Subgrade Preparation. Surfaces to be lined shall be smooth and free of all rocks, stones, sticks, roots, sharp objects, or debris of any kind and shall be approved by the Engineer prior to liner installation. The surface shall provide a firm, unyielding foundation for the geomembrane with no sudden, sharp or abrupt changes or break in grade, except as shown on the plans. Bends indicated on the plans shall be field fabricated using Manufacturer's recommendation and approved by the Engineer.

No standing water or excessive moisture shall be allowed. The Contractor shall certify in writing that the surface on which the geomembrane is to be installed is acceptable before commencing work.

(2) Weather Conditions. Geomembrane deployment shall proceed between ambient temperatures of 32 to 105°F. Placement can proceed below 32°F only after it has been verified by the Engineer that the material can be seamed according to the specification.

Geomembrane placement shall not be done during any precipitation, in the presence of

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(3) Method of Placement. The liner shall not be installed with any equipment or tools that can damage the liner materials by handling, trafficking or other means. The method used to unroll the liner panels shall not cause scratches or crimps in the geomembrane and shall not damage the supporting soil. Panels of geomembrane shall be placed using a method that shall minimize wrinkles. A continuous layer of geotextile shall be installed over the geomembrane. The geotextile shall have a minimum overlap of 12 in.

to adjoining sheets.

(4) Field Seams. Individual panels of geomembrane shall be laid out and overlapped by a maximum of 4 in. for an extrusion weld prior to welding or 5 in. for a hot wedge weld prior to welding. Extreme care shall be taken in the preparation of the areas to be welded. The area to be welded shall be cleaned and prepared according to the procedures of the material manufacturer. All sheeting shall be welded together by means of integration of the extrudate bead with the lining material. The composition of the extrudate shall be identical to the lining material, or all sheeting shall be welded together using the hot wedge welding system.

The welding equipment used shall be capable of continuously monitoring and controlling the temperatures in the zone of contact where the machine is actually fusing the lining material to ensure that changes in environmental conditions will not affect the integrity of the weld.

No “fish mouths” shall be allowed within the seam area. Where “fish mouths” occur, the material shall be cut, overlapped, and an overlap extrusion weld shall be applied.

(5) Field Seam Testing/Quality Control. The Contractor shall employ on-site physical non-destructive testing on 100% of all welds.

A quality-control technician furnished by the Contractor shall inspect each seam. Any area showing a defect shall be marked and repaired in accordance with HDPE repair procedures.

A test weld 1 ft. long from each welding machine shall be run each day prior to liner welding and under the same conditions as exist for the liner welding. The test weld shall be marked with date, ambient temperature, and welding machine number.

Samples of weld 1/2 in. to 7/8 in. wide shall be cut from the test weld and pulled by hand in peel. The weld shall not peel. Seams shall exhibit a film tear bond. The weld sample shall be kept for subsequent testing on laboratory tensometer equipment in accordance with the applicable ASTM standards. Random weld samples may be removed from the installed welded sheeting at a frequency to be approved by the Engineer.