ARAMOHB DRAINAGE.

Wanganui Chronicle, Issue 12857, 19 December 1912, Page 2

ARAMOHB DRAINAGE.

REPORT ,BY BOROUGH ENGINEER

Mr. C. N. Staveley reported to the Borough Council ou Tuesday evening as follows on the Aramoho drainage scheme: —

I have investigated this matter, with the aid of the data left by my predecessor, and am now in a position to submit the following report, which deals with that portion of Aramoho .between Russell Street and the railways; consideration of tho remainder being held over pending further surveys (being made. Levels.—lt has been assumed that the levels on record in the office are correct. I have had no opportunity of checking them, and of courso have no reason to doubt their accuracy, itnrfc the salient points will be checked before the work is commenced. Capacity of Sewers. —The drainage of Wanganui is based on what is known I as the "combined" or "partially-com-bined" system, that is to say both fitormwater and house-drainage are ad- i mitted into the same sewers. Jf the combined system were carried out in its entirety, the size and therefore the cost j of the main sewers would be very great, j but a recognised modification is to provide sewers of sufficient capacity to deal ■with the drainage of all houses that may be expected to be built on the area served, and also a portion of the stormwater, the balance of the latter being assumed in times of heavy rainfall to find its way into the river, by natural water-courses. This is known as the i "partially-combined" system 5 and it isl on this basis that the present scheme is worked out. The capacity of the sewei'S is such that ordinary rainfall, up to the rat© of two inches in 24 hours, is allowed for, but the sowers may be expected to be gorged, temporarily during excessive falls, such as a quarter of an itich in the hour, which occur only at rare intervals. Area Served.—With regard to ' the district under consideration, _ the position is complicated by the existonce (a) the Russell St. culvert, and (b) the Kaikokopu Road sewer, both of which it is desirable to bring into use, if such can be effected without detriment to the efficiency of the scheme, and after careful consideration I am albte to state that a good and practicable scheme incorporating both these works can be carried out. I may also point out here that: —(1) Provision has been made as to the size and depth of pipes for future extensions up to the boundary of the Borough; (2) sewers arc "proposed to be laid at present only where subdivision and building have taken place. Lay-Out.—The scheme consists of ■» main line of sewer ISin. in diameter, from the Russell St. culvert to Bal--1 larikie iS:b. via Russell, London, and Spier Streets, with 6tn. branch sewers in all streets except Ballance St., where 9in. is provided. These, together with the Kaikokopu Road sewer and extensions when required, will serve the areadescribed, •with the possible exception Of that (portion east cf Kaikokopu Road known as the Chinamen's gardens; this however, as Mr. Gilmour pointed out in his report of July 22nd, can be otherwise dealt with. / Cost. —The. estimated cost of these works is as follows: — £ s d 18in. pipe sewer on concrete foundation 27.6 eh. at £44 1214 . 8 0 Din. pipe sewer on concrete foundation 26 eh. at £13 10s. :. 351 0 0 Gin. pipe sower without con--crete foundation, 98. 5 eh. at £7 10s 738 15 0 Manholes, 20 at* £15 300 0 0 Junctions, -340 80 0 0 Concrete under Gin. pipe where -necessary 70 c.y. at £2 140- 0 0 4in. verticals on deep sewer 10 0 0 Extension of culvert at outfall ~ 60,0 0 Timber, lighting, and concontingencies, cay 339 17 0 £3,234 0 0 The .amount of loan money allocated for Aramoho water and drainage and unexpended to date, is £9,834, leaving a balance of £6.600" for the remaining portion of the district.