RIVER GROYNES

Manawatu Standard, Volume LVII, Issue 178, 29 June 1937, Page 5

RIVER GROYNES

SUITABLE TYPE OF PILES. REPORT OF ENGINEER. At last month’s meeting of the Palmerston North River Board there was a. discussion on tho question as to whether it was not “penny wise and pound foolish” to continue with the use of blue-gum piles lor groyne work instead of iron-bark or concrete. Eventually it was decided to refer the matter to the consulting engineer, Mr E. Fisher, for an expression of opinion and his report which was received) was presented to yesterday’s meeting of the board.

“It is correct to say that some of the I blue-gum piles in use for ten years arc showing signs of decay,” Mr Fisher stated. “This only applies to a small percentage of the piles in use. 1 estimate that in judging the present condition of the majority of the niles in use, their effective lire time, would at ' least be twenty years and upwards. With reference to the suitability of I iron-bark or concrete piles, I agree | that iron-bark piles are tho most efiijcient and suitable for groyne constrjic- | tion, and do possess the required stability and durability. This has been fully recognised by past boards, but owing to the limited financial re- | sources and the extensive groyne requirements past boards were obliged : to adopt an economical policy regard- | ing the piles used in order to provide sufficiently for the groyne scheme requirements. For this reason alone the blue-gum piles were used. “1 do not consider reinforced concrete piles suitable for groyne constructional purposes. The impact of heavy logs in times ot high floous would fracture these piles. In support of this, concrete piles used in wharf construe tion at Auckland some years ago I proved unsatisfactory, being fractured !as a result or the bei tiling ol boats, ! and iron-bark piles had to be driven to protect the concrete piles from i shock. Another instance of the instaI bility ol reinforced concrete telegraph poles was experienced in the Wai-ra-rapa a tew years ago, being [lie result of a cyclone and extensive and complete destruction of these poles occurred. The stress imposed on the poles by cyclonic conditions is similar to that of such piles exposed to the intense impact of logs under high river iiood conditions. 1 would therefore advise the board not to entertain the use ot concrete piles, but to play safe in determining the piles for future use. “I would advise the board,” concluded Air Fisher, “to continue the uso of only the best quality blue-guru piles procurable, in my opinion this is necessary on account of cost to meet the board’s groyne requirements for the current year.”