54 STAT.] 76TH CONG., 3D SESS.-CH. 333 -JUNE 12, 1940 No part of the appropriations contained in this Act shall be used for the operation of a testing laboratory of the highways department for making tests of materials in connection with any activity of the Dis- trict government. For personal services, trees, and parkings, $26,780; For contingent expenses, trees and parkings, including laborers, trimmers, nurserymen, repairmen, teamsters, hire of carts, wagons, or motortrucks, trees, tree boxes, tree stakes, tree straps, tree labels, planting and care of trees, and tree spaces on city and suburban streets, purchase and maintenance of non-passenger-carrying motor vehicles, and miscellaneous items, $110,000; Refunding erroneous collections: To enable the Commissioners, in cases where motor-vehicle registration fees, motor-vehicle opera- tors' permit fees, motor-vehicle title fees, motor-vehicle fuel taxes, importers' license fees, special assessments, or collections of any character have been erroneously covered into the Treasury to the credit of the special fund created by the Act entitled "An Act to provide for a tax on motor-vehicle fuels sold within the District of Columbia, and for other purposes", approved April 23, 1924, and the Act entitled "An Act to provide additional revenue for the District of Columbia, and for other purposes", approved August 17, 1937, to refund such erroneous payments, $1,500: Provided, That this appropriation shall also be available for refunding such pay- ments made within the last three fiscal years prior to the fiscal year for which this appropriation is made available: Provided further, That this appropriation shall not be available for refunds authorized by section 10 of the Act of April 23, 1924. WATER SERVICE The following sums are appropriated wholly out of the revenues of the Water Department for expenses of the Washington Aqueduct and its appurtenances and for expenses for Water Department, namely: WASHINGTON AQUEDUCT For operation, including salaries of all necessary employees, mainte- nance and repair of Washington aqueducts and their accessories including Dalecarlia, Georgetown, McMillan Park, first and second High Service Reservoirs, Washington aqueduct tunnel, the filtration plants, the pumping plants, and the plant for the preliminary treat- ment of the water supply, ordinary repairs, grading, opening ditches, and other maintenance of Conduit Road, purchase, installation, and maintenance of water meters on Federal services; purchase, care, repair, and operation of vehicles, including the purchase and exchange of one passenger-carrying motor vehicle at a cost not to exceed $650; purchase and repair of rubber boots and protective apparel; printing and binding; and for each and every purpose connected therewith, $513,350. For the development of a plan to insure an adequate future water supply for the District of Columbia, including engineering and other professional services by contract or otherwise, without reference to section 3709 of the Revised Statutes, the Classification Act of 1923, as amended, or the civil-service requirements, $20,000, to continue available until June 30, 1942. For a new pump and electric-control equipment for the Dalecarlia pumping station and for each and every purpose connected therewith, $70,000. 339 Use of funds for test- ing laboratory, etc. Trees and parkings, contingent expenses. Refund of erroneous collections. 43 Stat. 106. 20D. C . Code §§831- 848; Supp. V, §§ 831- 847. 50 Stat. 676. Provisos. Availability of funds. Exception. 43 Stat. 108. 20 D. C. Code 1840; Supp. V , §840. Maintenance, etc., of aqueducts and ac- cessories. Meters on Federal services. Plan for adequate water supply. 42 Stat. 1488 . 5U. S. C . §§ 661-674; Supp. V, §673, 673c. Dalecarlia station equipment.