RANGITAIKI LAND DRAINAGE

Bay of Plenty Beacon, Volume 2, Issue 225, 14 October 1940, Page 5

RANGITAIKI LAND DRAINAGE

CHIEF ENGINEER'S REPORT ©REDOING, CONSTRUCTION AND 'MAINTENANCE' The activities of the Department of Lands and Survey in -connection with drainage opera tion carried out on the Rangitaiki Plains for the year endJedl ■March 31st, 1940, are reviewed! in the report of the Chiief Drainage Engineer, Mr R. L. Innis, presented to both Houses of the General Assembly. Mr Inni's states:-— In accordance with the provisions r Rangitaiki Land Drainage QlO, I have the honour to sub;mit tfie report on .the works carried •out on the Rangitaiki Plains during the year ending 31st March, 1940 The rainfall recorded at Tliorn'ton. was 33.21 in for the year 1939, and 39.19 in for the fiscal year ending 31st March> 1940. The wettest month was June, when the fall was ' "5.07 in, and the driest month March ■with a fall of I.6in. The average rainfall, at Thornton over a period •of 22 years has been 52.*27 in. The ;year under review has the lowest recorded rainfall, the highest being 11936, with a tola! fall of 68.35 in. i Increase in Production.

Hie low rainfall lias not been injurious to production, and the general opinion of the settlers is that ■the results of the farming activities 'of the season have been exceptionally profitable. The Rangitaiki Dairy Co, which handles a large proportion of the -dairy product of the district, manufactured 4395 tons •of butter during the period of 12 anonths ending 31st Ma!rch, 1940, •compared with 4256 tons of butter xluring the same period in the preceding year.' The actual increase in -production for' the season is, how"ever, greater than these figures indicate, because, production lagged in the spring and was exceptionally well maintained into the late autumn, and the output of. butter for the dairy season ending 31st jVIay 3 1940, is expected to be a record for the district. Many farmers report increased production from Smaller Jierds. 1 / Maintenance of Canals. To carry into effect the /Tecent legislation to restrict the Construction of drains likely to .Endanger the Tarawera River improvements ~v/orks, a survey has been carried •out which reveals that drains have ibeen and are being constructed on the river banks which may be the --cause of' breaks in the river stop.•banks.

The activities of the Department ~have ' been principally connected Svith the maintenance of canals and •drains, and the only noteworthy •constructional undertakings have l>een the completion of the Orini Stream flood gate and the raising •of the stop-banks on the'right bank of the Tarawera River. More, rapid on the last-mentioned work Trvill, be made possible in future by the employment of an additional •excavator. Dredges The excavating plant, has now been increased to five drag line machines by the recent arrival of n useful light machine of this type from Pongakawa. The total output of these machines was 200,000 cubic the year. No. 1/ Monighan Drag-line excava tor has been continuously employed •deepening the Kopeopeo Canal. Working down-stream the machine reconditioned 3 miles 12 chains of ■canal, and at the end of the year liad reached a point approximately 35 chains from the flood gate at the outlet. Operating a 1-cubic yard bucket the machine excavated approximately 90,000 cubic yards of material. No. 28. Light Bay City Drag-line cxcavator has been used for crane work and driving sheet piling for the construction of the Orini floodgate. It also excavated 15 chains of by-pass channel to connect with the flood gate and repaired the Wha Icatane River stop-bank near the mouth of the Te Rahu Canal. The quantity of excavation was 16,000 ■cubic yards. Recent Addition to Plant. No. 30 Bay City Drag-line excavator has, except for interruptions <lue to breakdowns, been continu-

ously employed enlarging the stopbank on the right bank of the Tarawera River. This work has now been completed for a total distance of 3 miles upstream from the Railway Bridge, and 55,000 cubic yards of material was placed to complete! mile 22 chains of stop bank during the year. No. 31 Light Diesel Drag-line excavator is the recent addition to the plant. It is equipped with a 65 horse-power engine and operates a % cubic yard bucket on 40ft boom. The machine was delivered in January, 1940, and after a complete overhaul commenced work in February, 1940, on the right bank of the Tarawera River n(ear the F'actory Road. Approximately 2800, cubic yards of material was excavated from the river and placed on 5 chains of stop-banlc. No. 32 Light Diesel Drag-line excavator, after completing some repair work on the Mangaroa drain, commenced work early' in the year on a drain enlargement scheme involving 66,000 cubic yards of excavation from the Edgecumbe catchwater and Seccoiiibes drains. This work is being carried out principally to provide drainage for an area of 6700 acres of the Putauaki Block, which is being developed by the Native Department. Heavy reconstruction at the lower end of the catchwater drain has now been completed for a distance of 1 mile 15 chains from the Rangitaiki River. The output of this machine for the year was 36,000 cubic yards. No. 6 Priestman Dredge, which lias been laid up for some years, sank in the Awaiti Canal and was, raised 1 and beached in a safe position. Flood Gates The large flood gate commenced last year near the mouth of the Orini Stream has been completed. This structure comprises three sft. diameter east-iron automatic gates which will prevent tidal flow up the Orini Stream. As a protection agains.t erosion of the sand under the base of this structure, the entire fouundation was enclosed with steel sheet piling. To avoid the difficulties of underwater construction, a site for the structure was chosen where it could be constructed ?n excavation, and though this site was over 300 ft from open water, special methods had to be adopted to reduce the pressure of the percolating water beTore 'the concrete foundation slab could be laid. A nejwi channel has been excavated to carry the stream flow through the flood gate, and the old channel, will be

closed next summer after allowing time for the banks of the new channel and -filling to stabilise. A small flood gate and 3ft. diameter culvert was constructed on the Orini Stream and another of 4ft diameter completed on the Offlcheii Canal. The deepening of the Edgecunibe catchwater and Kopeopeo Canal necessitated alterations to two bridges, and a farm access bridge was constructed on Central Drain. Rangitaiki River River channel improvement worlt commenced" some time ago lias been continued. During the year the right bank of the river was cleared of willoAvs-for a distance of 86 chains upstream from the Edgecumbe Bridge. Bank protection work has been assisted by the absence of severe floods in the river. Tarawera River Freedom from floods and the temporary repair work carried out last year accounts for the fact that there were no breaks in the left bank stop-bank of the Tarawera River this year. It was pointed out in a previous report that the condition of this stop-bank is a menace to the district, and arrangements for the reconstruction and maintenance of this bank are matters of urgent necessity. Some bank protection work was carried out above the WhakatancTauranga Stale Highway bridge. Maintenance The Department undertakes the maintenance of 158 miles of canals and drains. This work is carried cut with mechanical excavatoirs and weed-cutting launch in the canals and larger drains and by manual labour in the small drains. ' The total length of the drains constructed by the Department to date is as follows;— (Continued at foot of next column)

Dredger canals G8 miles 43 chains; main drains 121 miles 36 chains; road drains 30~miles 46 chains. Summary of work carried out during the year:—■ Drains and canals cleared by manual labour 123 miles 36 chains; drains and canals widened and, deep ened by manual labour 4 milles 74 chains; drains cleared with weedcutting launch 14 miles 74 chains; drains and canals improved with excavator 5 miles 60 chains; new canals constructed with excavator 15 chains; stop-banks constructed oi repaired with excavators 1 mile 35 chains; stop-banks repaired with manual labour 8 chains; river-ibank cleared of willows 1 mile 6 chains; flood-gates completed 3; bridges erected 1. Surveys carried out involved: Traverses 171 miles 25 chains; levels 23 miles 19 chains.