"POLLUTION PROBABL Y FOAM’

Press, Volume CX, Issue 32361, 29 July 1970, Page 1

"POLLUTION PROBABL Y FOAM’

A complaint from the Pleasant Point Yacht Club about the “serious pollution” problem in the Estuary between the sewage pond outlet and Bridge Street was reported at the Christchurch Drainage Board meeting last evening.

The chief engineer (Mr P. J. Me William) reported. that samples had been taken and examined to assess the quality of Estuary water at Bridge Street and, for comparison, at Pleasant Point, on the side of the Estuaryremote from the yacht club.

“These samples do not indicate ‘serious pollution’ in the area of the club. “It is probable that the club is concerned with foam. The analyses indicate that the concentration of detergent is very low. It is insufficient to cause serious foaming in the absence of considerable turbulence.” By carrying out work at the four outlets to ponds six and five it would be possible to reduce the amount of foaming considerably/ but .it would be unlikely to remove the foam entirely, Mr McWilliam reported. ■ 1 , He said that considerable investigation had been made over the last two or three years to find a reasonable answer to the foam problem, but no economical solution had been found.

He said that foam could be reduced by discharge at the! high part of the tide cycle, but that this would involve extra labour and penal payments. Changes in the weir; level could be achieved auto-| matically, but the cost would; be likely to prove prohibitive.l “To remove the detergent I from the final effluent by any chemical or physical process would be exorbitantly costly. If the board considered the matter of sufficient importance to pursue, it would be necessary to construct a pilot installation on the site,” the report concluded. The board decided, without comment, to inform the yacht club that tests showed there was no serious pollution; it; was also decided to supply the 1 club with the chemist’s analy-j ses.