HEAVY RAIN IS CAUSE OF STREET LAKES FORMING

Star (Christchurch), Issue 18642, 20 December 1928, Page 11

HEAVY RAIN IS CAUSE OF STREET LAKES FORMING

DRAINAGE OUTLETS IN SQUARE ARE INADEQUATE

After a few hours of heavy rain, 'which set in at 7.15 this morning, there were street-floodings throughout Christchurch.

In Cathedral Square conditions were particularly bad. Water in sheets up to ten feet wide spread out from the side channels, and there were undrained lakes in the centre of the roadway.

The floodings were due to insufficient tapping by sewers of the storm channels and the choked condition of the pipes and gratings.

By the New Brighton tram stop, opposite the Godley Statue, there was aliood which extended eastwards as far as Worcester Street. To make this flood, water flowed right round the < athedral from opposite the Bank of New Zealand. All the way down the south-east side of Worcester Street Hast water flowed to the corner by the Government Buildings, and it was joined by the flow from the small sheltershed by the bank and round the east side of the Square. To relieve the .flood, there is a single outlet, leading underground to the corner by the Government Life Insurance buildings. It is interesting to follow the course of the water which leaves this particular flood. Crossing the Square westwards, it emerges into the open channel by the Government Insurance office and flows down to Everybody’s, Theatre. Opposite the foyer the channel is covered, but the culvert cannot, carry the water, most of which flows over the top. It travels on round the corner of the Square to the A.M.P. Buildings, where there was perhaps the biggest lake of the lot this morning. From here the fall follows what used to be an open channel down Worcester Street West. Six months ago this channel was covered at the request of the Tramway Board. This has reduced its capacity, and while the lower part runs full, the part which is open to the street is a real nuisance. As it is flat, it spreads the water all over the pavement and street, and pedestrians have no option but to walk through. The object of covering the channel was to leave room for cars to pass trams. “I warned them what would happen/’ said the City Engineer, Mr A. R. Galbraith, this morning. “They’ve reduced the carrying capacity of the channels, and been no gain of carriage-way. because the cars park on the extra space/’

In the opinion of Mr Galbraith, storm-waters are carried too far before the channels are tapped by the underground storm-water sewers which lead into the river. One of the storm-water areas is bounded by Bealey Avenue. Victoria Street, Salisbury Street and Manchester Street. It includes C-ran-mer Square on the south and extends as far as Colombo Street on the north. All the water from this area is concentrated in open channels on the intersection of Victoria and Kilmore Streets, and serious flooding is the usual thing there. There is one old outfall down Kilmore Street, and two years ago a second one was laid down Chester Street from the same point. In the opinion of the City Engineer the- surface water should be tapped at Salisbury and Conference Streets. Some of the channels carry water half a mile. “ Portsmouth, in the south of England, is a flat city, just like Christchurch,” said Mr Galbraith. “ I was district engineer there, and we made it a practice never to carry surface water more than 300 feet.” Tide Blocks Outflow. Mocrhouse Avenue is very susceptible to flooding, and this morning the pavements at the comers of Colombo and Manchester Streets were well covered. The Drainage Board engineer made an inspection and reported that all the channels and sewers were clear. They are not big enough. The water was rising up the sewer and flowing out of the man-holes. The outfall from Moorhouse Avenue is into the Heathcote, near Radley Bridge. When a rain like this coincides with a high tide the fall is stopped and the streets must remain flooded till the tide turns. RATE OF FALL. The heavy rain set in at 7.15 this morning, and by noon half an inch had fallen. The fall was heaviest between 8.45 and 9.15, when over a fifth of an inch fell. 3 Already 4.4 inches have fallen this month. For the whole month of December this amount has been exceeded on only three occasions since 1902. It is fifteen years since this happened last. Between 9.30 a.m. and 1 p.m. 51 points fell.