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Reprinted from ri a or ' City,County and State Manhole Rehabilitation Cuts 99 1 & 1 ) ) RAY THOMPSON to prevent infiltration problems, the top. It did not take us long to de- Public Works Director, water poured in through cracks cide against the first alternative. Dig- Burlington, Oklahoma wherever the water table was above ging up half the manholes in town, and the bottom of the manholes. many of them buried beneath city J. HERNING In addition to infiltration problems, streets, would be disruptive and Sanitary Inspector, many of Burlington's manholes also cost-prohibitive. Therefore, we Oklahoma State Department of Health had inflow problems. Water poured sought an effective way of solving the into manholes around the lip of the town's I&I problems inside the man- THE town of Burlington,Oklahoma, cover and through the "keyhole" on hole. 1 in northern Alfalfa County had a top. Prior to adding a new cell to the Help again came from the town's problem. sewage lagoon system, it was clear engineer. Gene Myers recommended Over four inches of rain had fallen something would need to be done to that the town look into a "Manhole to the north of town early in July 1983. correct the "I&I" — infiltration and Rehab System" offered by Preco Floodwaters were now inundating inflow — problems in the system. Industries Ltd. of Plainview, New the west side of town. Basements Our first step was to get in touch York. A complete set of instructions were flooded, roads were covered, with with Gene Myers, the city en- on the Preco system for sealing the and some houses had water inside. gineer. Myers Engineering im- interior surfaces of manholes was ob- The sewage lagoons were overflow- mediately set about conducting an ex- tained. As it turned out the system ing, while manholes located on the tensive review of Burlington's sewer consists of four distinct steps. west side of town were allowing huge system to identify the location of the Before starting to apply anything quantities of rainwater into the sani- worst I&I points. inside the manhole, however, it was tary sewer system. Lift pumps were Two Alternatives recommended that the sewer lines straining 24 hours per day to keep up coming into the manhole be"purged" with the exaggerated flow. The south Myers then recommended one of and flushed with an oxidizer, and the cell of the sewage treatment lagoon two alternatives to the city — either inside walls of the manhole be washed was beginning to overflow its dike, excavate around the outside of the of- thoroughly with a firehose and, in and a complete washout appeared fending manholes and reseal them some cases, scrubbed with a deter- imminent. from the outside, or find some way to Ray Thompson, Burlington's cer- seal them from the inside, including. (Continued) tified operator, felt he had little 0 BOWL-SHAPED"sewer guard"was placed in manholes that must be kept accessible. choice. Since the outfall box had been _,.. plugged with concrete years before, fir •. _ permission was now requested from the Oklahoma State Department of Health to use a 10-hp pump to dis- charge directly from the primary cell, -4 in effect bypassing the sewage treat- ment system. Authorization to bypass `� ✓ was permitted on an emergency basis only, and Burlington was placed on the high priority list of communities needing system improvements. It took many weeks for the flow in the Burlington sewer system to return to near normal. Visual inspection of r manholes quickly revealed the rea- sons. Many of the manholes showed signs of extensive infiltration by groundwater. All the manholes in the R'► �` tl .,, ao`ti system were of brick construction, •�'.aILI „t:- approximately 20 years old. While f};- ` supposedly plastered on the outside i `-`• _. '• I+ ��• ."? `= a