RIVERS COMMISSION.

Hauraki Plains Gazette, Volume XXXII, Issue 4303, 12 August 1921, Page 1

RIVERS COMMISSION.

The Waihou and Ohinemuri Rivers Commission, consisting o£ Messrs H. J. H. Blow (chairman), W. S. Shortt, and G. Buchanan, resumed, its. sittings in the Paeroa Courthouse PAYMENT FOR BENEFIT. Any man whose land was benefited by river and drainage works should be rated ; if the putfalil of a drain was improved the property that drain ran through was benefited. Toe Ohinemuri River was of benefit to Waihi as a mining sludge channel. The drainage of the Piako drainage board’s areas was into the Waihou and the Piako rivers. The Hauraki Plains were made by the alluvial deposits of these rivers. The putting of mining tailings into the river was regarded as ,a natural right by the mine owners. ' ■

To Mr Montague: About 40,009 acres of Crown. lands would benefit by,the river works, less 7000 or 8000 acres of Native land.

/ To Mr Richmond: The-greatness of the volume of silt deposited *on the land after the 1910 flood was due to the fact that that flood scoured out the old tailings deposited in the .early days, and not mere,Uy the silt- deposited just prior to 1910 only. A river carrying detritus would fill up if the quantity of water was -reduced,- It was heavy tailings, and not fine slimes, that were.found in the material dredged for stop-banks. The fine slimes would be held in suspension in the water, and. not precipitated to the" bottom. No mining tailings or slimes were deposited into the Waihou. . MATAMATA’S LIABILITY. The land at Okoroire was now .'’,ll ploughed land, and in rainy weather the light pumiceous soil was washed down into the Waihou, all that .area being in the .basin of the Waihou. The works done under the 1910 Act were substantially drainage and reclamation works, .their only benefit to mining interests being .the fact that they were guards against compensation claims owing to the river being used as a sludge channel. THAT £150,000. To Mr Cliendon: The cost of the protective works . was estimated- by the 1910 Commission,, but not based, upon engineering data. Commissioner Shortt : There were two competent engineers on the Commission, and they must have had ai: i idea of the cost.

Mr Clendon : They stated it would be from £130,000 to £150,000, so they were not definite.

Witness admitted ..that sinc.e the estimate was made materials had risen immensely in cost, steel going up by 200 per cent.. Pucyrus dredges .had gone up by 90 per cent. ; wages were double. Both the stop-banking and the dredging for enlarging th' ' same improved navigation. Paeroa was geographically, the centre of the ■* ■ T area affected. Mr Clendon: Do you know any other town which willi benefit more than Paeroa by the river wprks ?—No.

Did not the lemoval pf the willows benefit Te Aroh,a by improving the navigation of the W.aihou ? —Yes, Should Te Arpha share some of the burdeh ?

There •should be ; a wharfage rate charged on the goods' shifted,up the river and credited to'the river imports fund. There should not be a direct levy, unless the town discharges sewage into the river. The object of dredging the Ohinemuri was to improve the river for navigation up to the Ngahina wharf. THE REAL REMEDY, The best way of dealling with the debris in the Ohinemuri was to construct stop-banks and leave the rest.

to nature. There would be a tendency for the matter held in suspension to precipitate in the still water places. Mr Clendon: What proportion of the the improvement works would you attribute to the .mining interest? —Ten to twelve per cent. Mr Clendon: Do you think the Government should pay as a landholder, in addition to the one-sixth-now contributed ? —No, I would impose the burden on the land only.

Witness said there -rWere 30,000 acres of Crown lands and about 7000 or 8000 acres of Native land. The whole of the lands to ,the east of the Piako River were benefited by the works. The water jv,ent direct from the Awaiti to the Piako as far as Kerepeehi. There was a belt of titree on the Awaiti which would be an island in time of high' flood. The drains were a subsidiary way of draining the Awaiti, but the main way was to prevent the overflow of the Waihou River. The floods had a bad effect, upon the outlets of the whole of the country between the Waihou and the Piako. The Elstow drainage district had an outlet into the Waihou for the Thames Borough endowments, but this was not the right outlet; if should be via the Awaiti. The drains and cuts had all

been laid out to cope with a flood of

the 1910 magnitude. »To Mr Richmnod: The works were necessary, whether there had bepa mining or not. THE NGARARAHI CUT. The Ngararahi cut had not caused an influx of mining silt into the lower Ohinemuri. The Extraction Co, he had estimated on October 16, 1912, could take 950,000 tons of tailings out of the river ; this was within 50,009 tons of the actual. Boats could not get up tp Te Arpha now had it npt been for the clearing of willows, etc. There were some bad .snags near the old Extraction Work®. About a mile of dredging was required. NAVIGATION TO PAEROA. Commissioner Buchanan: If that mile of dredging were done, could boats come up to Paeroa railway wharf as in the old days? Witness : Yes, 'launches and boats like the Kopu could come up. This vessel drew four feet.

This degree of navigability would be a great benefit to the town ? —Yes.

Would the Waimarie and the Taniwha be able to come up if that dredging were done ? —No, they draw five and X six feet.

What depth would there be at hign tide if that mile were dredged ? —Six feet.

Xo Mr Richmond: Perenekis. cut would obviate the need of dredging. Commissioner Buchanan : Is there any reason why Perenekis cut should not be made? —No. It, should cost S less than £lO,OOO to make it navigable.

Commissioner Buchanan: Did you notice any appreciable difference in the flooding at the Ohinemuri River after the Ngararahi cut w.as made ? Yes. The flood - wafer got away from .the Waihou, and also the Ohinemuri backed up the Waihou and got relief by the cut to some extent. The ‘Rotokphu cut also assisted. He noted an accretion at the Wairaarie bend, about fifty feet wide, ,of mining silv. He had not rioted .any accretion of mining silt since 1910, except on Mill Road. Bet.ween Mangaiti and the top of the Ngararahi cut two-thirds, of the water in the Wathou River would overflow into the Hauraki Plains. South of Mr Wiggins’ house and -Mangaiti the, would flow at 6000 cubic feet per second; threefifths of the flow .would go that. way. The land to Hopi shoulld be rated,' :je it benefited. He took bearings as far as Pohongo for the proposed Pate-tonga-Awaiti canal.

To Commissioner Blow. The rainfall in the Waihou basin was about 40 inches, and in the Ohinemuri double that. The Perenikis cut would not .need to be .lined. Clay banks with a barter would stand, The current ran at five feet per second. If this cut were put through the river would clear itself of silt. Paeroa should pay part pf the .cost. The two rivers seldom flooded simultaneously ; the Waihou to,ok three days to go down; but the Ohinemuri only five hours. He would favour a special rating area within the Ohinemuri watershed. He wanted a regulating lake below Perenikis bend in order to have a flood basin, where silt would settle. This basin would* cost,£6ooo. The Ohinemuri and Waihou rivers were so interdependent that they had to be' considered con-

jointly. The cost should be provid< d among all those using the river in any shape or form. The land for the basin would have to bp bought, but its value could not be much, as it would always be subject to floods. He would certainly advise that the land should be bought. The cut would enable the river to get rid of mining debris. •

To Mr Porritt: The denudation of the timber on the Waihi hills had caused the washing down of debris. Mr Johnstone : The area has been re-affprested' with ti-tree.

Witness r Around the town of Waihi itself there has been tree-planting, biit not back into, the hills.

To Commissioner Buchanan: The water of the Waihou ‘had taken, on one occasion, three weeks to go down.

Mr Blow: Could the mines have been carried on advantageously without the Ohinemuri as a sludge channel ? In South Africa they have no riyer and have to stacks the tailings, but there might not be room in Waihi for stacking. ,

A COMPREHENSIVE CONTROL.

Moore F. Hazard, mining engineer, of 25 years’ local experience, said he considered the drainage of the whole of the Hauraki Plains and of the Piako and Waihpu river watersheds should be under, the one control, and one scheme prepared to deal with it. Replying to Mr Johnstone, he understood that the 1910 Commission was not set up to deal with land reclamation, but to devise measures for relief against floods. Mr Young observation regarding the flow of water from Mangditi across the Plains were in accord with those given by witness to the 1910 Commission. The removal of willows on. the Waihpu had been beneficial to navigation, but the tendency would be, especially after the Ngararahi cut had been put in, for the fiver to regrade and be swept down into the lower Waihou. The river sands were on the move always, from time immemorial these sands moved down .towards the sea. .Drainage, cultivation, road-making, all tended to loosen sand and soil which would be washed intp the river, THE CLASSICAL EXAMPLE.

He agreed that Coleman’s drain had discharged enough sand into the Waihou to fill up the bed for a distance: of twelve miles. Other drains acted similarly, but Coleman’s was the outstanding example. There was a great deal pf erosion in the sandy sub-soil of drains. In 1910 ne estimated that the Waihpu was bringing down 1,200,000 tons per annum of matter held in suspension, in addition to sand being dragged along th.e bottom. About 2000 acres of the Awaiti had benefited by .the Ngararahi cub. The stop-ihan® from. Thorp’s bend to P.aeroa was a valuable protective work to the town of PaerpfL Most of the land damaged in 1910 had recovered and were green paddocks.- All these lands had increased in selling value since 1919,. The flood of 1910 brought dpwn the accumulated deposits of many years; however., this scouring out improved the river. The fine slimes now produced were carried out in solution. The “Textbook of Geology,” page 359, stated that sand one-fifteenth pf a millimeter in diameter would float in slightly .agitated water ; this corresponded to an 80-mesh screen. The arnount of solids that tne average river would carry in suspension was 1 in 1500. Since the Ohinemuri carried off double this amount in 1910 it should now carry the half—whicn it was at present reduced to —very easily. The area of the Ohinemuri and lower Waihpu river bed between Waihi and the sea was’ approximately 2500 acres. To cover 'that to a depth of one foot would take 4,000,000 tons of tailings. The mining silt in the river had never been the cause of floods in the river; .the protective works would been necessary had there been no mining at all; but the mining aggravated the effects of the floods. The amount of mining debris by comparison with that brought down from agricultural lands was negligible. Works above Ngahina would bear no relation to mining. Lands which were swamped in 1910 were now good farms.

- WAIL ABOUT WAIHI. Witness went on to say that owing to the number of mining reserves (400 acres in all) the town of Waihi was a difficult one to manage municipally. These reserves could not be touched. He had bought a freehold section of one acre for* £3. There was no demand for sections. The bulk of the houses sold went cither to th-! Hauraki Plains or the Waikato. Dozens, perhaps hundreds,, of sections had been voluntarily forfeited when the owners left Waihi. The average price of the houses would not be more than £l7O or £lBO, principally because mining was insecure. There was only one brick. building, and two brick walls. .

WAIHOU FLOOD. In 1917 the Waihou was in flood, but pot the Ohinemuri. The flood covered the Awaiti Road at Nethertpn, and had also been two feet deep on the road at Tirphia—Springdale road, the depth in the swamp being four feet; this water had come down the Awaiti drain, near the Netherton schooli This state of things verified evidence he had given to the 1910 Commission. * THE REASON WHY. Mr Porritt: Was it not a fact that the Waihi Borough wanted to embrace the mining properties in order that Ohinemuri should not get all the gold duty.—Yes.

Mr Porritt 1 ,That accounts for the large area taken in, including much farming and agricultural areas that were never used as residence sites. They w.er.e taken up in blocks of sites so as to make f armlets to grow produce on. Did you not ge.t £3 per head of population ? Is there any Other local body in New Zealand that has ever been in such a happy position ? —No reply. Mr Porritt: Was not the 1910 Commission set up because of the complaints of damage done to the Ohinemuri owing to mining Yes. And do you agree with the findings of the Commission ?—No. SOME POINTERS. Have not the works at Ngai’arahi a beneficial effect in helping tp ’carry the mining tailings out of the lower Waihou ?

I consider the river would carry tailings off without the cut. Dp you make that assertion seriously ?—I db. ' Would you be surprised to know that 75 per cent, of what you call “slimes” deposits along the bed and banks of the river ?—Yes. Are not the fine grindings you refer to a. greater danger than the coarse stuff ? . I have not seen it. It sets like leather and is harder to shift than sand ?—I should say not. Do you know that the Extraction Company ‘treated those fine green tailings ? —No. Do not the Ohinemuri floods over the right bank of the Waihou carry silt over with them ? —Nothing appreciably. Would, you be surprised tg

that the tailings .ar,e still lying there, several inches thick Only near Bertelsen’s farm, near the Extraction Works.

Would the selling value of .the silted lands .not have been greater stillhad they not been silted ?—Possibly. Another flood would still carry a large amount of tailings down ? —No. Then how do you account for the 61<d Waihou bed filling up ? The same thing; would happegn if a cut were made near Te Arolia.

Then it is not all going out 'So sea ? Any silt will settle.

And this fine mining silt settles harder ordinary silt ? —I don't think so.

Is not the part below the Junction the, place which would benefit most by the Ngararahi cut ?—Yes.

r And you would nqt expect to find silt. there ?—No.

If all these deposits are washed out to sea, would you not expect to find some in the Firth of Thames and the Hauraki Gulf ? Yes, they are there.

Then you disagree with the finding of the Thames Harbour Board engineer, Mr Biair Mason ? —No reply. Are you aware that the bed of the Ohinemuri River from Mackaytown to she Junction has been raised since the* river was declared a sludge nel, until it is now pnly half the depth ?

I ha\e no knowledge on the matter. How many houses were removed on to the Waihi Plains ?—A good number.

And are occupied by Waihi residents ?—Yes.

And some went out to the Waihi beach ? —Yes.

Mr Gilchrist, junr.: The Ngararaai cut and the clearing of the .willows has lowered the water and damaged navigation ? I could not say.

Assuming that it is so, would dredging remedy the condition ? —Yes. The uppei- Waihou 'is .the mala drain in the Waihou watershed ? Yes.

Are not the streams in Matamata County gigantic in comparison wita Coleman’s creek ? —All waterways bring down debris. Do. you think Waihi has been extravagant ?

Yes, in"the early days. A voice: We had better stay there for a week-end and see. Mr Clendon: It will) not be able to be extravagant after this*commis~sion has.finished. (Laughter.), To Mr Montague : He- agreed that Waihi Borough benefited by the improvement of navigation, and should pay towards such work. The area of the Waihi Plains was 3000 acres.

To Mr Richmond: A very small stop-bank on the Ohinemuri would stop the overflow and prevent the deposit of silt, but would not keep back high floods. A little dredging would have restored the balance which was disturbed by the mining operations, had not noticed any fresh daffiage by tailings since 1910, though he had looked cjarefully for tailings. M? Burgess, who was perhaps the finest warden New Zealand had had, held that the mining slimes would be washed out to sea. The reduction of slimes to one-third by comparison with 1910 output would allow the river .to clear itself without dredging. Between 10,000 and 20,000 tons of rock had been put into tne river at Karangahake as the result of railway and road operations. The Rising Sun was the only company now putting mullock into the fiver, but only in small quantities. Two quarries, one the blue metal quarry below Owharoa were putting debris in. The river would deal more easily with the slimes than with .the metal. Floods which left a slime damaged the vegetation irrespective of niihing ■slimes. ‘

Mr Richmond: You were told by Mr Porritt how lucky Waihi was. Ohinemuri County has ‘got £200,000 in gold duty. All the dead spots would be filled with debris, apart from mining, and then the whole lot would go out to sea.

WEDNESDAY’S SITTING. Resuming on Wednesday morning, the chairman, Commissioner H. J.. H. Blow, said the area taken put of the Piako County to form the Hauraki Plains County was 20,100 acres ; out of Thames, 57,600 ; out of Ohinemuri, 140,000, these figures being approximate.

Continuing the cross-examination of M. F. Hazard, mining engineer, witness, in reply to Mn Hanna, said the mine gear had been designed to put the tailings into the Ohinemuri. Mr Hanna: Did Paeroa not get the stop-banks merely because they were necessary for the rest of the district ?

Paeroa gets a direct benefit, A gap in the stop-bank work would nullify the whole. The stop-bank on the continued otherwise those lands would continued, otherwise those land would suffer.’ The tide had a damming effect and would 'cause deposit of the solids in the water. He had never known the Ohinemuri keep up in flood for- more than a day or two. The tidal effect, by damming back the river;, caused gtill wa,te'r, favouring precipitation of the solids. VOLUME OF DEBRIS. Mr Hanna: If the debris from Coleman’s drain would fill up 7 miles of the bed of the Waihou (1,500,000 tons), would not 2,000,000 tons of tailings fill up 9 miles of the bed of the Ohinemuri, which is a smaller river ? Yes, probably. Mining could not be carried on payably if the tailings had to be stacked. Mr C'lendon : Would your evidence be warped in any way by the interests which employ you ? I hppe not. You believe in a river board. Yes. A board of commissioners, the best men tha.t could be got. Would not a board so far-reaching in its interests be cumbersome and costly ? —No. IS SILT HARMFUL ? Can you produce any person who will say there was any suggestion of protective works before the commission of 1910 ?—No. not that commission set up

in consequence of the flooding pf the lands, and the siltatipn of farming areas It was set up on account of the flooding. Tne completion of the works would benefit the whole district. Was it not a fact that the flopds prior to 1910, when the mining silt was deposited, .were not considered harmful ? Floods arc always harmful).

.Mr Clendon read evidence of Mr White, before the 1910 Ccmmission, stating that prior to 1910 the floods did not injure the land, Mr Thorp and others., some of 30 and 40 years’ residence, were quoted to similar effect. Mi- Hazard maintained that Waihi was not the cheapest town in the Dominion to live m, but it was cheaper than many. The Waihi G.M.. Co.’s mining area was only about 30 or 40 acres out of a much greater total acreage. He could no.t state the approximate life of the Waihi mine. It was possible that there was a still richer gold-bearing 'zone not yes touched. Assuming .there were no flpods the depositing of the 2,000,000 tons would not be harmful, except co navigation. The Ohinemuri floods, had covered the Rptokohu district, but only actuality damaged a very small area. Rotokpfiu land had al ways been submerged. If the-fiasis of rating were disturbed he was not prepared tp suggest an equitable reallocation. Paeroa town had been very considerably benefited by the improvement works. Waihi Borough would only benefit by the improved navigation up to Paeroa, but the benefit was very small. He understood the bulk of Waihi’.: imported gopds came by beat to Paeroa. Direct benefit wduld commence at M,ackaytown and extend as far northward as say, Wharepoa, where the stop-bank-ing would cease, for the river b were higher downstream. He had made no classification of the Hauraki Plains land, but believed the improvement work already done would -carry all water coming dpwn. To Mr Johnstone, witness said the augur process gave an absolutely true section of the deposits in the bed of .the stream. He explained in detailKnight’s section —a vacant business site in the centre of Waihi —would be hard tp dispose of at £4O. Many such sections were liable to forfeiture if the Mining Act were strictly enforced. Silting at the mouth of the Waihou was due to willows there colleo ing silt and shoals being .thus formed. More bush on the western slop? of the Te Aroha range had been felled than on the other side. Many thoiv sands of acres had been partial’y cleared and grassed. On .the Ohinemuri side the bush had been cut for milling and mining timber, but very little of it was grassed. This area bad gone back to second growthWaihi’s rainfall Was not as heavy now as in former years. Mr Johnstone handed in rainfall .records taken by the Waihi official observer.

To Mr Buchanan: If the mile < f dredging were done he . believed steamers would be able to bring cargo to Paeroa wharf. He had heard that the shipping company s preference for the junction wharf was due to the short time only available between tides. The old Ruby was probably faster than the presentday boats. Good alluvial' land would not deteriorate in value by havin'g three inches of mining tailings deposited thereon, though it may be necessary tp replough and resow that land again, Replbughing and sowing would cost £6 oi’ so per acre. He would not say such mining deposit would benefit the land. It would cos’: £6 per acre to restore land each time a flood deposited three inches of mining debris. Ou his. own farm at Waihi he put approximately' 3% to 4cwt of manure per acre. His land was nothing like as good as the Plains oi’ Paeroa land. He considered the whole watershed of the Waihou, Waitoa, Piako, and Ohinemuri streams should be under one rating authority. He believed more sand went into the Waihou than into the Piako or Waitoa, for it traversed a greater length of pumic.eous country. The whole of the Thames Valley and Hauraki Plains should oe brought into the scheme, under one local body. Settlers north of Wharepoa wduld indirectly benefit. Classification would be based upon the benefits derivable. Fish would not live in silt-Jaden waters. He knew of no fish, even eels, in the Ohinemuri, but they were fairly plentiful years ago. To the Chairman: The one controlling authority, as he had suggested, could levy direct rates, 6r* through smaller local authorities. The latter course would probably be more economical and equitable. A differential rate would be struck. (Still sitting,)