CORRESPONDENCE

Evening Star, Issue 17320, 7 April 1920, Page 3

CORRESPONDENCE

Every Utter must be accompanied fi.v th* name and address of the writer, not necessarily for publication, but as a guarantee of good faith. Rejected letters cannot- be returned under any circumstances whatever. ST. CLAIR BEACH PROTECTION. TO TH"B EDITOR. Sir, —This much-thought-of trouble at ] St. C-lair Reach is one that cannot be dealt with by inexperienced men. 'flie value of the seaside resort to j Dunedin is by no moans small, and j whatever the cost may be to pro- j tect the foreshore, it must be a work of permanency. One only has to travel throughout Xew Zealand to see the 'value of seaside resorts. Viewing what has been done for the benefit of the community of Otago at St. Clair, with its baths, esplanade, and other attractions, and the ultimate connecting of St. Kilda by a further extension of the St. Clair esplanade will make the locality one if not the best seaside resort in New Zealand. The beach lias to be maintained, and to formulate a plan for the protection of tfie sand banks from the erosion of the sen it must be sought for at one point only—viz.. at the bluff near the swimming baths. This locality is practically an open roadstead, where the full force of a southerly gale rages, and with its high sea and tides sweeps almost in a direct, line to the dressing sheds, where the sand bank is being washed away, as there is nothing to prevent the velocity ri the wave action pounding on the banks. Certainly groynes aro no rise; this is nroved. Yon have them there, and know the result. Ono has therefore to initiate something apparently not thought of if the authorities determine to cone with the trouble on common-sense lines. If it is the intention of the authorities to continue the concrete wall, and to undertake works of a larger nature than simply protection the sand banks, then they must direct- their attention to a work of constructing a causeway to act as a groyne at the point near the swimming baths. This causeway will require to be thros or four chains in length and about 10ft wide on top, and built up to about !!Bin above high spring tide lev"!, consisting of bon!;-l.'i-s to hve?k the force of the

->vnv--> action, and thus I- 3 .-;,-"!! tire velocity • if thp ware? on the sand hill. The cost of such work-should not he expensive, as millions of tons of stone are available at the rock bluff, and. if necessary, the snid-? of the. road could be reduced to provide additional stone. Tim causeway need not be br.ilt in the ordinary way. but thp 3 ton? cm be placed in position by I chute from the rocky face of cliff, or. ;f considered more economical, trucked to thp work. Pnswilily it jp the intention not to <?xfpnd the concrete wall, and seek only temporary repairs. If this is the os'C then T fusae-st that a matt-re?? of mnnnl-a Ta?cines be la ; d consisting of manvK-;, fascines 12ft t-> 14ft in length and 1?; m to 15in in thickness, when secured by wire he placed at, ricrht annles to-the lire of ?ii-d hank, built up on a nf about 4Me~ to a height of 18in above high tide level. If tho fascines are pron-rlv pieced and packed so that on completion, they one mass in the form of "str-piiiiK" from the seaward si-e from beach level up to the required he'iT'st. it wili be found that the fascine* will gradually become •embedded in the sand, end the oeach i-:= not disfigured : to lay f.-s-ines in any other way only b"ie.,- s failure. This form of protection io hanks where the sea. is washing awav fbe sand has proved a success in many vnrts of Xew Zealand, and it should prove of value at St. Clair. Piefore entering upon any work in the form of protection I should suaccst that 'he eontrolhnr; authorities visit- Clair Beach, ?o to the Icc.ilitv of the swimming ba'i,-. and view the position from there, and"" possibly they will find the cause of the trouble has to be d-->n!t with at the bluff.—l am, etc., St. Clair. April 6. TO THE KDITO"Sir,—Tt seems to be. afto r all that has been r-aid apainst groynes and the sad experience that has resulted from the pre- j sent groynes, that "the Orean "Reach Himain Board still intend to proceed with this obsolete method, which will only result in further <lestr""tion of the beach. Tt is a. well-known fact that when nil* piers ar(? placed i n rivers, as in bridge : construction, if the bottom i<= of soft mate-ial. such pr sand. etc.. the action | of the current is to deepen around the [ mips, and this is what actually happens with piles plac--d as they are- at present nt the Ocean Beach nt St. t'lai". ' When grovnes are put in a river to protect- the j banks they are placed at an angle to the ] current. The piles are also 010 = e-lviarded from low water-mark to about the highest known flood level, thereby acting as a'lead to the river current awav fr"m the ban'- ! ■ which is to be- protected. Xow. this is I | common sense and good engineering : but ■ .".i'nno.= ;nii an engineer came along, and ; when requested to put in cjrovp.es to proi tect the river bn!; he placed a number ; of piles in a. line at low water-mark lonki in:r y-> stream. T ou would probably sa.v be i had take--* 1.-nve of bis series: vet tins is what the Ocean Peach "nomain BoT'd are doing at the beach at St. Clair. The beach if not a river bank, and cannot be (reared as such. nn d this is the mistak" of present engineering advice. • -. hat engineers r-.-onire to re"ocrr.!~e- is that it i* the ffrcup; unde'-tow that they have to deal with, and that this undertow's motion is direct-Iv away from the shore Tnere are certainly a few whirling eddies rear the shore, hut thev are moVly on toe sip-face The undertow -> a.s nearly j as possible directly awav f,-o- the shovo'. | therefore means must be f,-,.,r> r 7 *.i counto'--j act this undertow Ky rcduci-c- its sneed or by the .need of the o„co m i.; wa.vr-s to- some obstruction. There are various wars by which 'bis m ;„v t i, e fono._- Pnt- whatever is' done by" the Domain Ponrrl tho most vrr: , n y j, t]l( , sr.Klhdl protection This has now so far that nnthine- short- of a m'>hl> or concrete wall «d'l 1 H effective " Tbi* soonld be done witbnirt. debar becn-isp apa-t fr ? m spoiling the b-nn+Jfnl sandbibs. ~ ,s reovrrod fo„ the public M f of ,- 1., hope the board will pn t . rer-eat the same d-,gn of wall n, at present in use at he T ,.„ with a bfit'nr nf H M 1. or concare. wifb lip at top. The present den'gn of v -.iP .and the groynes are responsible for = n d dcstrccf ; on of the sandy beach That- use-d to be there I may here .fate that T am a native of Dunedm and Inve known the beach tor >a period ot 40 year,. T am also aengineer jod drnit.sman. c n that whet. T say may have some weight j ..-r,,,!^ strongly adviso that the Vovnes should be all withdrawn-! all thn, P nt present in positmn-and that no further groynes l-.e made.—T am etc A P ril 6 " "_R? Walker. OUR SEASIDE "RESORT. TO TiTE EDITOR. Sir,-On3 hardly knew whether or not to take senously your remarks in Saturday's issue, which appeared to bo devoted chiefly towim.B heaping anathema on those responsible ror the erection of th 0 esplanade and partly in eulogising- tie m.i-nificent work clcno by Mr _ Hancock in standing by and .ensunr-g against accident the hundreds of peon,- who made use of the upper road on Good Friday. If any credit is due to Mr Hancock for wishing to stop the building of the esplanade, ho certainly is entitled to it The improvement agitators," as von designate them, were an executive consisting of Messrs A. Bathgate, M. Cohen, Dr Howard. Messrs C P. Johnston, P. S. K. Maeassey ,T Mlnaoe, J A. Park, J. A. X. Reidle, Dr Hoberts, Messrs C. R. Smith and J. H i, ,1 a PP° lnte d at a public meeting called for the purpose of soe.ing -what coulS t ~ e l . + ° ,ln P rove the neglected condition of the front, and otherwise make our holiday resort more attractive. Surely a very representative body of citizens! The Press—the "'Evening Star' especially —were most generous in their praise o'f what was proposed to be done, and we were 'aroatly indebted to them for lielo in enabling- the T,-ork to be carried through. In addition to the esplanade, the executive were successful in persuading the council to Require land and build conveniences, shelter and band- rotunda, etc. We will suppose, as Mr Hancock says, thai the esplanade wall

is responsible for the present condition of the beach. What would have been the result it it had not existed, with the heavy seas we have had of late? But there is ample evidence it has nothing to do with k. . In February of this -rear there appeared in the ' Otago Witness' a number of photos taken of the beach, ono of them i taken in 1914, just two years after tho wall f was completed, with the sund up to the foot of the wall, and again in 1817, after the beach had undergone many changes, -i The conditions were similar, with the groynes ' all but buried. 1 You have only to go to our second beach 1 and inquire what has become of the sand ( that used to be there. Only to-day I was ] informed that at Karitane rocks that used ( to be submerged with sand are standing r feet out of the water. No, sir; you must , look fed other causes for the denudation of , the beach than the work of the " improve- • meut agitators."—l am. etc.. ' G. A. Fenwick, ; Hon. Sec. to the Executive. April 7.