Drainage Mat Construction Specification: A Comprehensive Guide, High school final essays of Law

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DEVELOPMENT CONSTRUCTION SPECIFICATION - C

TWEED SHIRE COUNCIL

DEVELOPMENT

CONSTRUCTION

SPECIFICATION

C

DRAINAGE MATS

VERSION 1.

SPECIFICATION C233 - DRAINAGE MATS

• DEVELOPMENT CONSTRUCTION SPECIFICATION - C
• CITATION CLAUSE CONTENTS PAGE
• ORIGIN OF DOCUMENT, COPYRIGHT
• VERSIONS, C233 DRAINAGE MATS........................................................................................................................
• GENERAL
• C233.01 SCOPE
• C233.02 TERMINOLOGY
• C233.03 REFERENCE DOCUMENTS
• C233.04 ORDER OF CONSTRUCTION
• CONSTRUCTION
• C233.05 TYPE A MATS
• C233.06 TYPE B MATS
• SPECIAL REQUIREMENTS
• C233.07 RESERVED
• LIMITS AND TOLERANCES
• C233.08 SUMMARY OF LIMITS AND TOLERANCES

DEVELOPMENT CONSTRUCTION SPECIFICATION - C

DEVELOPMENT CONSTRUCTION SPECIFICATION C

DRAINAGE MATS

GENERAL

C233.01 SCOPE

1. This Specification is for the installation of Drainage Mats (Blankets). Scope
2. Drainage mats shall be constructed where and as shown on the design plans or as directed by the Certifying Engineer.

Location

3. This Specification should be read in conjunction with the Specification for SUBSURFACE DRAINAGE - GENERAL.

Associated Specification

4. Requirements for quality control and testing, including maximum lot sizes and minimum test frequencies, are cited in the Specification Part for Quality Requirements.

Quality

C233.02 TERMINOLOGY

1. Type A drainage mats are intended to ensure continuity of a sheet flow of water under fills, to collect surface seepage from a wet seepage area or for protection of vegetation or habitat downstream of the road reserve where a fill would otherwise cut the flow of water.

Type A Mats

2. Type B drainage mats are constructed to intercept water which would otherwise enter pavements by capillary action or by other means on fills and to intercept and control seepage water and springs in the floors of cuttings.

Type B Mats

C233.03 REFERENCE DOCUMENTS

1. Documents referenced in this Specification are listed in full below whilst being cited in the text in the abbreviated form or code indicated.

(a) Council Specifications

C230 - Subsurface Drainage - General C232 - Pavement Drains

(b) Australian Standards

AS 1289 5.4.1 - Compaction control test - Dry density ratio, moisture variation and moisture ratio.

Documents Standards Test Methods

C233.04 ORDER OF CONSTRUCTION

1. Type A drainage mats shall be constructed after the site has been cleared and grubbed and before commencement of embankment construction.

Type A Mats

2. Type B drainage mats shall be constructed after completion of the subgrade construction and before construction of the pavement.

Type B Mats

DEVELOPMENT CONSTRUCTION SPECIFICATION - C

CONSTRUCTION

C233.05 TYPE A MATS

1. Type A drainage mats shall be constructed under embankments as and where shown on the design plans or as directed by the Certifying Engineer.

Location

2. After the embankment foundation has been trimmed and any necessary trench drains installed, a geotextile complying with the requirement of the Specification for SUBSURFACE DRAINAGE - GENERAL, shall be laid on the embankment foundation. The area of geotextile laid shall be sufficient to cover the area of the Type A drainage mat and an additional amount for enclosing the sides of the drainage mat after the filter material has been placed. Laps of minimum width of 500mm shall be provided at each join in the geotextile.

Placing of Geotextile

3. Type C filter material or Type D filter material, as shown on the design plans or as determined by the Certifying Engineer, shall be placed on the geotextile and compacted to the satisfaction of the Certifying Engineer. The minimum thickness of the compacted filter material shall be 300mm plus an allowance for the expected consolidation of the embankment foundation under the embankment load or 500mm if the amount of the expected total consolidation of the embankment foundation is not known. The filter material shall be placed in two (2) or more layers so that no layer, when compacted, has a thickness greater than 250mm.

Placing of Filter Material

4. After completion of placement and compaction of the filter material, geotextile shall be placed on top of and around the sides of the filter material so that the filter material is completely enclosed by geotextile. The geotextile shall be secured in such a manner as to prevent movement of the geotextile by wind or by construction plant placing subsequent layers of filter material or earth filling over the drainage mat.

Securing of Geotextile

5. An additional layer of geotextile shall be placed on the drainage mat under the base of any rock facing which may be placed as part of the embankment construction. The additional layer of geotextile shall extend beyond the outside and inside faces of the bottom layer of rock.

Geotextile under Rock Facing

6. Care shall be taken not to damage the geotextile during the construction of the drainage mat or during placement of subsequent layers of filter material, earth filling or rock facing. Any geotextile so damaged shall be repaired or replaced by the Subdivider to the satisfaction of the Certifying Engineer. The cost of repairing or replacing such damaged geotextile shall be borne by the Subdivider.

Damaged Geotextile

Subdivider’s Cost

7. Type A drainage mats shall extend 2m beyond the toes of embankments and such extensions shall be covered by a 300mm thick layer of Type C filter material or Type D filter material, as determined by the Certifying Engineer. This protective layer shall be placed immediately after completion of construction of each drainage mat.

Protective Layer

8. Outlets from Type A drainage mats may be surface outlets at the toes of embankments or piped outlets connected to other drainage systems. Where piped outlets are constructed they shall conform to the requirements of the Specification for SUBSURFACE DRAINAGE - GENERAL.

Outlets

DEVELOPMENT CONSTRUCTION SPECIFICATION - C

LIMITS AND TOLERANCES

C233.08 SUMMARY OF LIMITS AND TOLERANCES

1. The limits and tolerances applicable to the various clauses in this Specification are summarised in Table C233.1 below.

Item Activity Limits/Tolerances Spec Clause

1. Filter Material

(a) Layer thickness 250mm max C233. C233.

(b) Compaction (Relative) Type A filter material

100% Standard C233.

2. (^) Type B Mats

(a) Design level at top of mat

+0, -40mm C233.

Table C233.1 - Summary of Limits and Tolerances