an extensive questionnaire. It includes description of the life history of the Teredo and the Limnoria the influence of temperature and salinity, character of bottom, purity of water, currents, resistance to attack of piles driven at different times of the year, resistance of various kinds of wood, nature of attack, changes in violence of attack, seasonal variations, depth of water in relation to virulence of attack, etc., etc. There is also extensive discussion as to protective measures and it is of particular interest to note the reference to successful protection obtained where iron nails were driven into piles. One of the most interesting parts of the report consists of two maps on which the distribution of Teredo and Limnoria attack is given in great detail, with particular reference to extent or virulence of attack. The Danish Committee established six grades, as follows: (1) Where the marine borers have been traced in one or more places but where it cannot be said that the attacks are of much practical import. (2) Where borers have been found here and there, but where attacks have done actual harm in only a few places. (3) Where the borers are numerous enough to destroy a pile 25 centimeter (9 inches) in diameter in the course of a period of ten to twenty years so that the same must be replaced. (4) Where such destruction occurs in the course of five to ten years. (5) Where such destruction occurs in the course of two to five years. (6) Where such destruction occurs in the course of one year. The indications on the maps clearly show where Teredo or Limnoria is responsible. Destruction of the sixth grade is particularly marked in the waters of Norway and Sweden at the entrance of the North Sca. FUTURE WORK: Realizing the international character of marine borer activities, the National Research Council was appealed to for the purpose of formulating a broad program to coördinate the various investigative activities now being conducted and to stimulate additional research work. A preliminary committee has been appointed which has drawn up such an outline. It is hoped that those interested will contribute and coöperate with the Research Council to the end that this plan may represent the broadest possible viewpoint. Your Committee strongly recommends that the A.R.E.A. continue to actively participate in the prosecution of the research work so necessary for a proper understanding of the habits of marine borers and methods for their control. RECOMMENDATIONS: The result of examination of service records of piling on all coasts during the past few years leads your Committee to recommend that good creosoting will offer the best protection so far found. By good creosoting the Committee means a treatment conform ing to the recommended practices of the A.R.E.A. both as to oil and treatment. We do not believe that there is sufficient knowledge as yet to warrant the use of special oils and that the A.R.E.A. No. 1 creosote oil should still be regarded as the standard for piling protection. (5) PRESERVATIVE TREATMENT to be used on piles AND TIMBERS IN LAND CONSTRUCTION O. C. STEIRMAYER, Chairman; E. H. BOWSER, H. A. DIXON, C. F. FORD, J. H. WATERMAN, Sub-Committee. The very high cost of replacing piling and bridge timbers which have failed through decay or other causes, necessitating often the rebuilding of the entire bridge, brings forth considerations of chemical preservation of such material unlike that of any other treated wood used in railroad construction. First cost of the treated piling should be of secondary importance. Zinc chloride and a combination of zinc chloride and creosote oil have been used to a limited extent as the preserving agent; however, your Committee is of the opinion that where the greatest degree of permanency is desired only creosote oil should be used in quantities which will insure thorough penetration in the treatable portions of each stick, and of such depth as will preclude the possibility of season checks extending beyond the line of treatment. Your Committee recommends the following additions to the General Requirements: Piling for Land Construction Treatment shall be in accordance with specifications for preservative treatment of wood with creosote oil (full cell process). The net amount of oil left in the piling shall be not less than 15 pounds per cubic foot of wood. Timbers in Land Construction Treatment shall be in accordance with any of the following specifica tions: 1. Specification for preservative treatment of wood with creosote oil (full cell process). 2. Specification for preservative treatment of wood with creosote oil (empty cell process, with final vacuum). 3. Specification for preservative treatment of wood with creosote oil (empty cell process, with initial air and final vacuum). The various processes of treatment shall be so manipulated as to reach a net retention of not less than 12 pounds of oil per cubic foot in all timbers, excepting bridge ties and guard rails in which the minimum amount may be not less than 8 pounds of oil per cubic foot of wood. Failure of some creosoted structures in the past can be attributed to untreated surfaces exposed to decay when sawing off piles, framing, and boring of holes. Your Committee is of the opinion that instructions for field treatment of creosoted materials are very necessary and offers the following: Instructions for Field Treatment for Creosoted Material All treated timber and piling which is cut or bored after treatment shall have the surfaces so exposed covered with creosote oil. Where cut, the surfaces shall be painted thoroughly with creosote. Where holes are bored, they shall be poured full of creosote where possible. Horizontal holes such as those for Sway Brace Bolts shall be filled by pouring creosote into them through a bent funnel. The creosote shall be heated before using. Where it is absolutely necessary to bore holes in piles to support scaffolding, or for other reasons, the holes shall not be left open but shall be poured full of creosote and a tight-fitting creosoted timber plug inserted. (6) METHODS FOR STORING LUMBER AND PILING FOR AIR-SEASONING PRELIMINARY TO PRESERVATIVE TREATMENT C. F. FORD, Chairman; R. S. BELCHER, H. C. BELL, C. E. GOSLINE, J. K. MELTON, J. H. WATERMAN, Sub-Committee. It is the opinion of your Committee that the top of the treated sills or stringers used for piling and lumber should be at least 12 inches above the ground instead of 6 inches, as now provided; and it is suggested that the Manual be revised to read as below, with the changes underscored: "Material should not be treated until seasoned. If it arrives at the treating plant in a seasoned condition, ready to treat, it may be loaded directly from the cars to the trams; otherwise it shall be stacked: If ties, they should be stacked in layers of one or two and seven to ten, depending on the width of the ties, with alleys at least 3 feet width between rows of stacks extending between tracks, and at least 6 inches off the ground on treated sills; if lumber, it shall be segregated according to size and each layer in the pile shall be separated by at least 1-inch strips with an air space of 1 inch or more between each piece of lumber in any layer. For caps, stringers and other large timbers, 4-inch by 4-inch strips should be used to separate layers in piling, with alleys at least 3 feet wide between rows of stacks extending between tracks and at least 12 inches off the ground on treated sills; if piles, they shall be stored in a like manner, placing only one length in a pile, using strips 4 inches by 4 inches or saplings of equal size between each layer; reversing all sticks in every other layer in order to keep the pile level, with alleys at least 3 feet wide between rows of stacks and at least 12 inches off the ground on treated sills. The space under and between the rows of stacks at all times should be kept free of rotting wood, weeds, or rubbish. The yard to be so drained that no water can stand under the stacks or in their immediate vicinity." The following paragraph should be added as the next to the last paragraph, under General Requirements: "In some localities, where weather conditions make it difficult to properly season piling or large timbers, it may be found desirable to locate the piles with ends to the East and West in order to secure direct rays of the sun on the ends of the sticks." |