THE RAILWAY WORKS ON THE RIVER BANK.

Patea Mail, Volume VIII, Issue 1024, 20 April 1883, Page 2

THE RAILWAY WORKS ON THE RIVER BANK.

The following is the Harbour Board Engineer’s "report on the above :—■ To the Patea Harbour Board : Gentlemen,—ln accordance _ with a minute passed at your last meeting that I should examine and report on the damage to the river caused by the railway embankment, and by the contractor not properly protecting the earth he is now tipping into the river, I have now the honour to to lay before you the following report. I have examined the S.E. bank of the river from the bridge seawards and find : That between the bridge and railway wharf where it is unprotected by fascines, the facing of papa has been softened by the water and the greater part washed away in the form of silt, and that the bank at that point is being gradually carried into the river. Between the lower end of the railway wharf and the piling, an embankment has been carried through what is commonly known as the mud flat, thus forming a tidal basin which is filled and emptied twice a day. This causes a strong current at the opening where the basin enters the' river. The end of the embankment at this part was, I understand, for a,length of time, totally unprotected, and, being_ exposed to a strong current, large quantities of the earth must have been carried into the river at the present time there is only a facing of papa, but I observe the contractor is beginning to pitch it with stone facing- This embankment for its whole length is in a very unsatisfactory state—more particularly the inner side, or •that next the tidal basin. This has no protection of any kind, and is simply soft earth, it is freely exposed to the action of the water, and is rapidly being carried into, the river* by the ebb tide. On the side next the river • the*embankment has been protected by the stems of fern trees laid horizontally and staked down. I have examined this work and find that it gives a very imperfect protection to the earth, which is being freely washed out through the openings between the stems, leaving large voids behind. Both sides of this embankment require to be properly faced, At the seaward end of the piling the railway is carried on an earthen embankment for a few chains till it gets on the solid ground in a cutting in the cliff. The embanfoment is. !-tlre ffpper ciul projects about Unity 01 forty feet from the -cliff into the river at its narrowest part, it is also on the concave side, so that it is exposed. ,_to the full force . the current at the :■ very .worst .place that could have been chosen. On Friday I saw the men forming the era bankment by throwing loose earth into the river at this place. The material-here at the present time is being carrieth iri large quantities into the bed of the river, and if a heavy fresh were to come on, the whole is liable and very likely „to be washed down. Further seaward, some attempts have been made to protect the face by blocks of soft papa rock. On examining them X found the papa was so soft that I could easily tear off .pieces four or five pounds weight, and these would crumble away in the hand like soft earth, so that the remedy was little better than the disease.

I also found along the clifl; several small gullies opening to the river, which had been filled up with earth. An attempthad been made to stop the main body of earth going into the river by facings of papa rock at the bottom ; but it was little bettor than that described above. Quantities of earth have evidently been thrown down these gullies without care being ■taken to prevent it getting into the river, as is clearly shown by the remains which are lying above low water in the shape of lumps of clay up to half a hundredweight each. The effect of allowing these embankments to remain in their present condition is to cause a gradual silting up of the river bed, with a kind of puddled clay, much worse to remove by currents and freshes than sand ; other Harbour Boards are paying from one to two shillings per yard to have similar - material removed from their rivers by dredging instead of allowing it to be deposited. This silling up is evident at various points, where recent deposits from one to twelve inches above the old bottom may be seen above low water mark, and also by the formation of a shoal dry at low water springs, which the pilot informs me has lately been formed where the river widens out, after being contracted by the embankment. Although I have been unable to examine this shoal on accQ.unt of the bad weather, it is only what I should have inferred from the strong back water I saw and which was caused as stated. I wish to point out that had the bridge or trestle work been continued for about three bays further, the worst portion of this embankment would have been avoided, and a permanent injury to the river prevented. The extension of the timber work would have taken the railway well round the point so that any embankment that would then have been required, would when properly faced, have done no harm.

Unfortunately as matters now are, even if the toe of the present embankment were properly finished, it will do harm to the river, because it would continue to act as a groin or jetty diverting the water from its proper course, and throwing the current over to the opposite bank, where in lime it will form a large hollow ; besides this making the channel crooked the river bed abreast of this groin, as i,

always the, case, will be scoured out into a deep hole and a shoal will form below

I observe the river bank at the “ Boiling Down ” has been washed away to a very considerable extent although protected by a rubble wall. This can easily be stopped by a few loads of shingle thrown at the back of the wall against the stones so as to . prevent the rush of water through the rubble ; it will then fill up gradually with sand. Exactly the same thing happened when the other part of this wall was being built, but as soon as the shingle was placed at the back it silted up. I have the honour to be, Gentlemen, your obedient servant, ' , , John Thomson, Harbour Engineer.