SMALL CANAL EQUIPMENT
Small canals encompass a wide range of cross sections, starting from concrete-lined distribution ditches with bottom widths (BW) as small as 30 cm (12 in.) and extending to branch, distributary, or even small main canals where BWs and depths can approach 2.5 m (8 ft.). In most cases, canals of this size are constructed on a prepared and compacted earthen fill (berm) using conventional earth-moving equipment. Once the berm is shaped, the full canal section is excavated and finished in a single pass. Typical side slopes for small canals are 1:1, 1.25:1, or 1.5:1, depending on soil conditions, design requirements, and intended hydraulic performance.
Excavation and Trimming Methods
Small canal cross sections are typically excavated or trimmed in full section using one of the following methods:
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A conventional excavator or backhoe equipped with a trapezoidal bucket matching the canal cross section, with excavation guided by laser control for accuracy. The subgrade accuracy may be low using this method resulting in higher concrete losses.
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Fine grading a conventionally excavated canal section using a digging chain attachment mounted on the front of a self-propelled, concrete slipform lining machine, trimming only 25 to max. 40mm (1–1.5 in.); this is a low-production solution.
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A specialized trapezoidal trencher like a G&Z ET6300 or ET7300 that excavates and fine grades the canal cross section in a single pass at high production rates and at high accuracy.
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For larger small canal cross sections, a full span configuration bucketline trimmer can be used to fine-grade the final 230–300 mm (9–12 in.) of a canal previously excavated by conventional earthmoving equipment. The accuracy is high using this method.
Concrete Lining Methods
Small canal cross sections are typically concrete lined using the following methods and concrete is fed to the Liner by concrete transit / truck mixers:
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A smaller Subgrade Guided Towed Boat Liner pulled by a front-end loader, motor grader, or self-propelled “Tugger”. Light and portable, these liners can be lifted in and out of the canal and maneuvered around obstacles in the canal alignment using equipment on site such as a front-end loader or the self-propelled Tugger.
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A larger Subgrade Guided Towed Boat Liner equipped with its own power unit and winch for self-pulling along the canal using a “Deadman” or piece of idle construction equipment to pull against. These liners require a crane for placement and removal from the canal and are typically supplied with a concrete distribution system. Larger liners can also be handled with a tugger.
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A three or four track Self Propelled Canal Liner equipped with a canal mold. Elevation and steering are automatically controlled in reference to a single stringline, a stringless guidance system, or by tracing the canal subgrade. With the mold removed, the liner tractor is self-moving around obstacles, while the lighter mold is moved / repositioned using a crane or on smaller molds, a front end loader.
