Arapuni sick : a million's worth of medicines : what then?

Hill, Henry, Office of Dinwiddie, Walker & Co., Napier, N.Z., 1930

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Title: Arapuni sick : a million's worth of medicines : what then?

Author: Hill, Henry

Published: Office of Dinwiddie, Walker & Co., Napier, N.Z., 1930

Reprinted fi om "Hawke's Bin He/aid" Xovembei 6th, 1930.

ARAPUNI SICK.

A MILLIONS WORTH OF MEDICINES.

What Then ?

(To the Editor.;

Sir,—Three Parliamentary pape - on matters connected wnh ine Arapuni hydro-electric power development and of tin' working on .Inn,. 7th last, have :>-il for public information since Parliament opened its recent session.

Minister's Report.

Mr. ["averner states that al 7 a.m., Saturday, June 7th, water was noticed on the floor of the battery-i the power-house.

Crack.

That when the officer at the pump end ol Ihe penstoi b was ci nnmunicat< d with lie found a crack -' inches wale between the Spillway and the structure near it. Water was found issuing from a number oi places behiud the power-

It is bardlv necessary to say tlnlt the papers are of great public i'miportif the community have reference to the Arapuni undertaking from the time when the initial - in to the time in June when the works closed down owing i" the appearance ol certain und defects.

The three papers are thus related:— 1. "Statement made by the Hon. \V B. Taver Minister of Public Works report embraces official information supplied bv Mr. I'\ W. Furkert engineer-in-chiei of i 5 Pu die Work ■ her technics I officers oi his de partment."

Cracks.

That a second crack was disi <<\ ered running from the first through the hill between the old gorge oi the Waikato liver and headrace. That I the flows and general movements decided the authorities to lower the water oid overflowing Spillway, and to enable a better examinati il the conditions being made. The gates in the Diversion channel were then opened.

"2. A Special Geological i 3 "Arapuni h- dron The reporl igned I iI- iderson, I'. Marshall and i A. Bartrum."

3. "Professor Hornell's report relating to the damn ok place at Arapuni hj dro-electrie pov ,n the 7th .1 me, 193

In su form the Hon. Mi r.'iverner's report and thai of the ire given below. Prol Hornell' no remark ra mendat ions <m information supplied bj reports I and 2

June 15,

That the Minister after an ins| nl the working conditions with the water ed until the head-race was drv.

Cracks

Tim ■■ examiui i ion numerous crack - wen found, ilow which water disappeared in quail

Leakages,

Thai aftei ihe » ater had been drawn ifl From the head-race, tlic le

.

That a similar lessening of flow in the power-house where water was seeping on the 7th mst. ceased.

Movements of Rock.

That following tests for rock movements ii was discovered that a movement had occurred, “definite in the direction from penstock to the tahrace, that is in ihe direction of the Gorge.

Power-house Turbines Moved.

Hon. Mr. made ■

Suspension Bridge.

I

tfi( low movement bad taken

report, "supports the theorv that the move-

Power-house Cracks.

On June 20th small era' i on the floor oi Number 2 Unit, and soon alter cracks nere re] bi ee machines and extendi I e upper machine floor down approximated to the top of the turbine and scroll i

Slips and Falls of Rock Material.

Following the emptying of die lake be v. ater hai diverted and the lake drained, that and urea: lulls of material occurred "from die cliff wall above the intake in the diversion tunnel," and the latter blocked three times.'

All the defects enumerated occurred wiiliin 12 mouth* of the opening of Arapuni and after reports had been made again and again, that the stability of the land warranted the construe tion of hydro-electric buildings.

Mar Auck

I

in paper D.1.8 b\ the •tahilIdings

n way, order Yet were itcome of dai in the

The repoi t D.] expert careful stud\ anrl to Arapuni the report. : paragraph of tl report.

as representing tin- 1,. each ■ . the river flowlow, the tl each downwards :

(a) a and gravel.

much jninteil columns rhyolite tuff.

(c) From 90 to 100 feet oi i pumice br»

Unknown thickness of taffaccoos . sands and broi

The rock latiom b), (c) lianiK support tlie viev that the ground chosen for building and so "n. should be firm, with

foundation. Rut lot the geologists speak for themselves

The Bra or upper group of bed- are said to bo "unconsolidated sands and and "need no further consideration." is the remark made concerning them ' Whv "no further consideration." when stability and secur ity are indispensable in the case of a great undertaking like the Arapuni hydro-electric development works. The second i hi and ,hird (c) formations are relatively strong rocks"'. Tliev arc nicks and when drv readily absorb water, the joints in them allow the pa-

Weathering accentuates these joints. which are conspicuous in the the diffs. The report continues 'B tween the columnar rhyolitic full and the pumice breccia are a few feet of - sting ol a poorly consolidated silty phase of the columnar tuff and thin beds of gravel, sand and clay." f'he-,. weak bed.-, especially the idedly impervious. The upper few feet of tl of beds indurated clays. The powerhouse is built on these beds, of which only a small area is exposed."

A novice reading through these stateinents and knowing how important it have firm and solid foundations would find some difficulty in reconciling tlie bed- enumerated as supplying all the necessary land of a sufficient ity on which to erect buildings demanding .strong foundations and security from erosive influem

Cracks, Leaks and Tilts,

The report however, goes on to point out the weaknesses which had been found in tin- very bed- under review. Among tin cracks ait- oi the workings, many leak- in the viciniu powerand tilu- in connection with the ower at the west end of the sushi bridge over the (lorgo. and at the "power-house," the tilt in each case indicating a .slope towards the

It due- not appear to have been a difficult matter 'or th< oal exthe many trie weakness ever carious part-- of the area at Arapuni, where it had been supposed then was solid and safe country to occupy, It i- assumed the experts were aware of the reports already extant as to the stability o\ the country.

OF NEW ZEALAND [.ess than Lwelve months had ;■■ since Arapuni had been pronounced sound i" every particular and many ware the well-deserved praises be-stowed on ad who had been concerned with the construction of what was at the time the greatest hydro-electrical undertaking in the Dominion.

The results ol a re-survey of tl xistintr conditions at Arapuni have ait clarified the outlook as to future dangers. The suggestions made by the . - as to ibe possibiliwi';ikm'SH's having appeared owing in tin engineering works undertaken, or of possible earth tremors, give jin satisfaction to an anxious public. Tin- instability of existing conditions are known to all who have visited the locality but after so much expert inquiry and so many assurances thflt everything was satisfactory but little consolation comes from suggestions such as the experts now offer. We are n.iv told that "tlie oauee of the fracture miM be definitely ascertained so that remedial measures may be taken.'' It i.s thus suggested ''that the strata beneath the power-house-he explored to a depth of 100 feet or more by shatis or by bores of largo enough diameter to yield a continuous core, and that the different rock layers he geologically examine,! and tested lor their strength and elastic properties." And pray who has beej saying for twelve years past that the Arapuni is solid and safe? The above are the conclusions arrived at by the g<-olngisns concerning the rocks ~n which the Arapuni establishment has been built! It wi: J given out in the public press again and again that everything was sound and stable above and'beam the bed- as exposed in the Gorge, although contradictions were insistent and many. But what can a Minister | what a Parliament in the face of a band of special:-!- who ■■re-survey'' the rocks embracing the Arapuni area and state as their mature opinion that ■'the evidence does not clearly show that the purely geological factors wete important in causing the crack (sic)." >ly they were sufficient in ii « nil Ihe definitely known en gineering -tr ■--<■- i,, rupture the rock already weakened by erosion of the channel formi.ig the headrace and by tic engineering excavations. Hut here come, the rub. "Tin cause o| the continues the report, "must he definitely ascertained s (l th.it remedial measures may be taken." And «hn .it the cause of the fracture- And who i.s to applv the remedj ? Surelj the experts who were

DOWNSTREAM OVEK THE SPILLWAY. The small buildii equipment f OT controlling the water flow through the penstocks is*. The ci begins in the concrete buttress in Front ol the control, house ami follows the direction i ( ~,1,1 ; ,i I! is two inches wide. When the "headrace" (1 e the R pilhvnv) is emptied o) water -hy releasing the lake water held in the 'lam proper through tin' diversion tunnel 11 1.■ possibilities ~| a fault extending upstream will !»■ fully mi

ARAPUNI THOI lil.l \l I in: AIK. Th< i;e is in ti„. lefl the inn- course "| tlie Waikato to I n them is a ridge nn which the transformers stand; the powerhouse is below these iu the gorge. The -pillway maintains twenty feet of water about the heads of the penstorks, A. lvlik-li L'arry water down to the |k>w<t station. Ii \ieai ai A that the fissui covered. It extends in the oivards tlie waterfall and the old forest. Note the distance between tin and the 'lam proper.

job should ho i " d a cause when o many i akness '\\ e suedes; tinue the experts "that the beneath the power-house be explored to the depth oi inn feet or mi or by bore- of large enough diameter to yield a continuous core, and that the .1 lieient rock layef - be examine,! am! t< sted For thi and "la-tic properties." Statements like IK i a hx k of information such as anyone interested in e public undertaking as the \ hydro-electric Installation should have ed and could easily have obtained by following thi Auckland or Wellington pr,

Thus the Auckland "Herald" of January 28. 1997 has reference to the rower-house difficulty at Aranuni and to excavations which had •iver level tor the Foundations of the power-house. "Is it -t the ennt-aetors did not te-i i i II the vicinity of the power-house, and arc there exists to-day wdio will affirm that .solid rock can be reached within ami undertaking ;1 t n depth o| 100 feet from the surface ~! the river? Why test,- have been made within the limit- ol the Arapuni workings to a depth exceeding 22 and nothing beyond volcanic materials lund. almost a- tine and a- varied a- the sands found to-day at Rainbow Mountain, near W.u-o-tapu. and known as kakaramea.

But what are people to think of undertakings and polite- when headaeh as the following appear in a leading newspaper ol file \. l-laial. "Security of Arapuni Dam". "Site and proved -ale", "No i for anxiety". '■Critic's information incomplete." Tin- i- the heading in the N.Z. Herald. Saturday. December 22nd, i it It an article covering the above point-. The information as far a- I could learn was in reply to a criticism upon Arapuni works then in progress of construction by Mr. R-. \V. Holmes but which I had not -ecu when _ 1 bought a copy of the Herald. Al the time I was travelling on the Main Trunk railway from Napier to Hamilton and Taupo intending to call af Arapuni by the win. With a party ol ladies ami gentlemen from Melbourne I visited various place- ol intere I among which were the dam and the spillwav. A geologist accustomed T "

I'canic country could read in a moment what was looming in connei tion with the area in the immediate track of tin' spillway. 1 picked up and I away with me six or pounds by weight, of pumice mk from the side 'of the spilln ay and it side now as I write. Long before, 1 had visited til "'1 the side test tunnel . er on the -wine; bridge to the felt bonk: climbed to the top of the terrace and took a general survey of the country. Hut my experiences on Christmas Eve 1928 more thai! i re, convinced :i trouble was brewing in connection witii la) tic of the rock materials at Arapun porosity of the rocks am! fc) the uncertain factor about which no th appears to have been given viz.. the effect of impounding waters in an imporoufi basin, with ; and bottom, and particularly in an area of some seven or eight s'quare miles and which had been drained and dry for many lone; year-. These were factors that loomed before me in mv mind and I wrote on my return to Napier a- to the future propects of Arapuni. On May 27th, 1929 "T5 - N land Herald", published a verv well written and interesting account headed, "Arapuni Dominion's greatest power scheme.'' It i- there stated why Arapuni "was -elected as the outcome of exhaustive investigations by a number til experts.'' Direct reference imade to Arapuni as follows:

"Last year doubts were raised in the public mind as to the suitability and stability of the Arapuni country for dam works by the publication of a statement in tin- name of R. "\Y. Holmes a Former engineer in Chief of tlic l'nlilic Works department As to stability Mr Holmes was oh with the idea that the country was full of earthquake cracks. Geological evidence? and engineers and geolc worked hand in hand and thej eluded, "that the gorge was cut by water in the ordinary way They estimate that for 10,000 years the Waikato followed the channel of the gorge." Statements such as the above cannot lw supported hy any dire* I eeec whatever. Geologists and >ers alike know as much about the time when Lake Taupo and the Waikato Valley country were fissured and washed, as they certainly were fissured :in,i washed, by floods of hot and cold water: as they do of the time when othei eruptions will occur at Maungatnutnri Vol. or Mount Tnuhara near

Pcwer-h:use Difficulties.

Taupo, or at N'gauruhoe or liuapeliu. lo the south oi the lake. A know of the ' the volcanic countrj with its interesting legendary sugof volcanic changes, should have suggested caution as to the length of time the Waikato river ha- flowed through tin' Arapuni Gorge. Ilarh--tetter in L 859 was in the vicinity of Arapuni and Maungatautari and remarks how- the Valley was filled, lie illowed in 1 by 1.. Cussen, wdio-e excellent account of the "Waikato River Basins," with map and plate of ancient land surfaces -how of what materials tho greater part of the Waikato basin i- composed. See Vol. XXI. I'ran. N.Z. In-t. pp4o6 - lib. But a much better insight of the Taupo and Waikato country i- obtained from the writings ot the two earliest scientific - to the central area of the N. Island.

first two seii in ists from Euj "i-' «bo traversed bhe Taupe and Wa kato coun. oils ~r 10,000 v s having passed by in the making of river and earthquake (rack-, such as they encountered this year. The cheery account in the "New /calami Herald" related above, as to the prospects at Arapuni was not to continue lor any length of tune. The Arapuni undertaking was ready for operating at the beginning oi July, 1989, and juice was supplied to Au. amid re- = and congratulations. Ilni on August 22, there appeared in the Hon" newspaper the following: "Grave trouble at Arapuni." "Heavy erosion at overflow fall." "Rapid wear threatens spillway." "Remedy involves serious altcrnal lve."

Bidwell visited the Upper Waikato. i and the Volcanoes to the South of tiic lake in March, 1839, and hi ' Rambles in New Zealand.'' p 28, "Ail the small rivers 1 have seen in the countn appear to have no valley, but to have tiic course excavated perpendicularly out of the plain to a great depth." (Earthquake fissures?). Again "Although 1 do not think the growth o| potatoes sufficient to account tor the i over a great part of the country, perhaps more than half. ■ lain the wood ha- dei for some cause or other within no great distance oi time, a- I constantly found logs of wood and roots lying in the wet ground of the barren 01001

Dr. DifTenbach. Vol. 1. p. 330.

\- already related in the Minister's statement of occurrences at Arapuni on .June 7. last, there was a 1 the opening in the previous July cause for congratulation at tin l accomplishment of so great an undertaking in the island, hut, now it turned in tin- story oi the ''house built upon -and." The caution thai had been given b.v the Public Works Engineer-in-Chief as to Arapuni in 1917, showed that the physical conditions thereabouts called lor additional investigation, and ho i d further inquiries as to the [ity ui nt ilismtr the Kaitnna river or the Waikato river at the Aratiatia rapids. To t]io suggestion Mr Parry said that ''neither compares favourably with the Arapuni development a- regards capital cost l M ' r hots,. power developed provided, of course, that no abnormal difficulties are encountered." And this was, and is. the crux oi the whole business. The Arapuni area, embracing the core,, an( j adjacent ground, contains materials that can only hi' understood by extending a geological survey for miles to the upper sources of the Waihou (Thames) and Us former connection with the W'aikaio further to the S. I

Dr. Diftenbach « ho visited the i olcanic country in 1840-4] from Kawhai b\ way oi the Waikato and Takaanu says: Vol. I. p. 330:— "If I wished to describe the country through which v.. I could not "or than b.v saying it resembled a Land over which a flood had swept, ' it torn in many places, ridged with terraces. How considerable must have been the volcanic eruption that pumice -tone and lapilli! These show where thev are expo ction a uniform character throughout and not to havi iie work of any in eruption. From the slight of decomposition which had taken pilli, J should imagine they must have been • .1 comparatively recent date." Clearly tho

It was after the report by Mr Parry giving favourable approval to the Arai roposal, |>L'f>\-ill*mI "!iu abnormal difficulties are encountered," that the ferred to the Mines Department for a special geological report. The late Mr I'. Morgan was then ni charge as director "I the geological survey, ami Dr Henderson was authormake n survej iU Arnpuni. I lis report lippears in Vol, I. So 1 ol Ihe Ni Zealand Journal oi Science, and

of the special reNo '-'. which the Hon. Mr Taveriior antic | by Mes I Marshall, and Bari .inn. follow iii"; the Arapuni catastrophe of June. I tied ihe authoril e Arapuni offei , , than en ol tla -ted.

;n in I!'i' I over ci'.ihiii up to .March last >ear. Ihe final work ha- been finished P W'eik-. following the 11 11l of the collt, W. < ; . Armstrong Whitworth, I.

Mam and unexpected difficulties, unanticipated and unthought "I by either engineers or geologists have suddenly appeared, showing instability where stability was reported to exist. The percolation of water through the nonted pumice material where uneven and wh composition ol ih.- beds d unexpected manner, has brought about ments ol al! the beds in tile immediate area el' the gorge. In one o| the drives near the | from which pumii - into a lorn at the date of my I i~n on S saturated with water and snowed that all adjacent beds were saturated from cause- "that in my view can lie traced. The conditions existing at the down of Arapuni when machinery. bridges, rocks and roadways had ■ d ret ace the work

ol hydro-electric production began in July I.' further suggestion whether i in the immediate vicinity of the dam and head aliened by the in ig nf the machinery for so long a period. From appearances n would seem i e upper beds are resting on a saturated 1 ..i -«- having the qual- ; cksand. M\ acquaintance with the c itry lead ippose that the soft volcanic deposits arc of great depth and that water passes through them like an underground river ; the manner of flows in an in water area like the Heretaunga i.l.iin - \\ i area in the immediate vicinity of the dam and head-race was weakened by the sant n the machinery gested for further inquiry. From appearancea it, would seem that all tfie upper base having tin- qua! quicksand. My acquaintance with the coundeptli and that water passes througb them alter the manner of Ileus in artesian beds.

tin has many wounds to be ': and if Pr ! can bring tlun i hi i ma. Ue will deserve well of this country. J.ikc a good pfiysician he recomm* nds what to adopt to remedy existii ditions, and it remains with the of the Public Works - immended should the report be adopts eminent.