H.—29
6
Sub-Enclosure No. 2 with Enclosure No. 4. Table II. —Table showing the Degree of Hardness, and the Proportions of Total Solid Residue, Lime and Organic Matter in the Reservoir-pool, the three Branches of Supposed Leak, and School Creek Spring, and Paper-mill Spring, all taken on Saturday, 17th July.
All the above results are consistent with each other, and with the theory that part at least of the water of the three branches of the flow is derived from the reservoir. The evidence in each separate case is stronger for the middle and the east branches than for the west branch.
Sub-Enclosure No. 3 with Enclosure No. 4. Table III. —Temperature of (a) Reservoir, (b) Supposed Leaks, and (c) School Creek Spring and Paper-mill Spring, on Wednesday, 21st July, between 10.45 a.m. and 11.40 a.m.
The temperature of the supposed leaks was taken at their point of issue from the foot of the embankment; and the result tends to confirm the theory that part, at least, of the water of each of the three branches is derived from the reservoir. The evidence, in harmony with all the other tests, is stronger in the cases of the middle and east branches than in the west branch.
Enclosure No. 5. COPY OP MR. HAY'S REPORT. Mr. E. Hay, M.lnst.C.E., to the Town Cleek, City of Dunedin. Sir, — Dunedm, 27th September, 1886. I received your instructions on the 27th July to examine and report fully to the Council on the alleged leak from the Northern or Ross Creek Eeservoir. I commenced work on the following day, and have now the honour to forward the result of my investigations, and, in doing so, shall endeavour to confine your attention to the plan of operations as pursued by myself, trusting my descriptions will be sufficiently clear to enable your Council to traverse the same grounds in their minds as I have followed in person. On visiting the locality I found water issuing at three points from the foot of a dry stone retaining-wall situated on the original bed of the creek, the wall evidently having been built to prevent a slope of. loose clay and boulders coming in contact with the water from the bye-wash shoot that discharges into the stream-bed at this point. This wall, it must be clearly understood, is not the foot of the reservoir-dam or embankment; but the level of the outflow of the supposed leak is actually 47ft. below the toe of the exterior slope of the dam proper, while the water that issues from the wall is 42ft. below the outlet of the scour-pipe at the well-tower, and 91ft. below the surface of water in the reservoir when full. As previously stated, water flowed from the wall in three distinct streams, which for reference sake may be designated the west, the middle, and east branches; and these have been separately gauged or measured every morning from the 28th July to the 26th September, and their various discharges duly recorded, together with the rainfall and corresponding depths of reservoir in the tables attached. On the first occasion (28th July) when I measured the flow of the supposed leak there was a depth of 18ft. lin. in the reservoir, and the total discharge from the three flows was 139-7 gallons per hour; and the last measurement taken by Dr. Black before the water was turned into the reservoir (after having been emptied, with the exception of a small pool) was 222-1 gallons per hour.
Degree of Hardness. Carbonate of Lime in Solution, in Grains per Gallon. Total Solid Organic Residue left on Matter, in boiling-down, terms of in Grains Grains per Gallon. per Gallon. Reservoir-pool West branch Middle branch East branch School Creek spring Paper-mill spring ... 34 4-7 4-4 4-3 7-0 6-4 1-9 '2-5 2-2 2-1 4-1 3-9 6-5 9-0 8-0 8-1 11-2 11-0 2-1 1-3 * 1-5 1-7 1-1 1-0
Temperature in Degrees Fahr. Difference in Degrees Fahr. between Supposed Leaks and Temperature of Beservoir. Difference in Degrees Fahr. between Supposed Leaks am Average Temperature of Springs. Seservoir ichool Creek spring... 'aper-mill spring iverage of springs .., Vest branch last branch .. . fiddle branch 41-9 51-8 50 50-9 48-02 47-5 47-3 6-12 5-4 2-88 3-4 3-6