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Home My WebLink About1976-09-21; City Council; 3771; Ponto trunk line siphonc CITY OF CARLSBAD AGENDA BILL NO. J 7/7 Initial: x-p Dept.Hd.CjC DATE: September 21, 1976 0 DEPARTMENT: PUBLIC WORKS _ _ C. Mgr. R Subject: PONTO TRUNK LINE SIPHON Statement of the Matter The City of Carlsbad, the Leucadia County Water District, and the Encinitas Sanitary District jointly own a sewer trunk line which brings influent from the south into the Encina Water Pollution Control Facility. A portion of this trunk line, which carries waste water under the Encinas Creek drainage channel, is in need of repair and modification to OSHA standards. Additionally, it needs some effort to eliminate a hydrogen sulfide problem. County Staff has recommended a course of action and provided for design and construction funds in the JAC budget. Local staff concurs in the repair and OSHA work but recommends additional analysis to determine a course of action on the hydrogen sulfide problem. EXHIBITS; A. Staff Report B. County Letter RECOMMENDATION: It is recommended the Council approve and authorize the Leucadia County Water District to proceed with an engineering analysis and subsequent design to resolve the hydrogen sulfide and OSHA problems at the Ponto siphon inlet and outlet structures, such engineering work not to exceed $2,500.00. COUNCIL ACTION: 9-21-76 Authorization was given Leucadia County Water District to proceed with an engineering analysis and subsequent design to resolve the hydrogen sulfide and OSHA problems,at the Ponto Siphon inlet and outlet structures, subject to such engineering work not to exceed $2,500.00, as recommended by the staff. MEMORANDUM - September 9, 1976 TO: City Manager FROM: Public Works Administrator REFERENCE: PONTO SEWER SIPHON The Ponto Sewer Trunkline is one of the main lines leading into the Encina Water Pollution Control Facility. This line, which lies parallel to and easterly of the railroad tracks, serves the Encinitas Sanitary District, Leucadia County Water District, and the southerly portion of the City of Carlsbad. At its entrance to the Encina plant site this trunkline must cross a major flood control channel. This is accomplished by means of a facility called an "inverted siphon." The trunkline enters an inlet structure which provides access to one of several lines which go down and under the drainage channel, then come up into an outlet structure. From the outlet structure the sewage influent flows directly into the plant headworks. The ownership of, and cost of operation of the siphon are shared by Carlsbad, Leucadia and Encinitas. In May of 1975 an inspection of the siphon inlet and outlet structures revealed that there were significant problems being created by deterioration due to condensation occurring inside the structures. In addition, there were several things that needed to be done to the structures to bring them into conformance with OSHA standards. The County, in a letter dated July 15, 1975, furnished information concerning the extent of work required for the inlet and outlet structures and an estimate of the cost and engineering for that work. Chemical analysis of samples taken at the inlet and outlet structures of the siphon reveal growing concentrations of hydrogen sulfide. County engineering staff has recommended the construction of a chlorination station at the siphon outlet structure to combat the problems associated with hydrogen sulfide. The cost of constructing the chlorination station, as well as performing the remedial work required at the inlet and outlet structures, is funded by an appropriation in the 1976-77 JAC budget. The technical staff of the three agencies met on August 11, 1976 to discuss the project. It was the conclusion of the technical staff that, before committing up to $10,000 for the construction of a chlorination station, the situation should be studied to MEMO to City Manager -2- September 9, 1976 determine if it is possible to remedy the hydrogen sulfide problem by a modification of operation and maintenance procedures. It is the conclusion of staff that the recommended course of action would be to authorize Leucadia County Water District to analyze the possibility of correcting the hydrogen sulfide situ- ation by modification of operation and maintenance procedures. In addition, the district should be authorized to proceed with the design of that work which is necessary to bring the inlet and outlet structure into a proper state of repair and into conformance with OSHA standards. Should the analysis of the hydrogen sulfide problem lead to the conclusion that a chlorination station or some acceptable alternate is necessary, the design of this work would be included with that necessary to modify the inlet and outlet structures. A total of $16,000 has been budgeted in the JAC budget to cover the cost of engineering and construction of the required modification. RECOMMENDATION: That the Leucadia County Water District be authorized to proceed with an engineering analysis and subsequent design to resolve the hydrogen sulfide and OSHA problems at the Ponto site inlet and outlet structures. Ronald A. Beckman Public Works Administrator RAB:ms BOUNTY OF XAN DIEGO Z RMBn8XW(XBtKSXKB£»OQK COMMUNITY SERVICES AGENCY Department of Sanitation & Flood Control C. J. HOUSON * J County Operations Center, 5555 Overland Avenue, San Diego, California 92123 ..... Telephone: 565-5325 15JULW5 RECEIVED 1 6 1975Mr. Ron Beckman City of Carlsbad r>t-r\/ /-\r- «.«. ~ 1200 Elm Avenue CITY OF CARLSBAD Carlsbad, California 92008 Engineering Department SUBJECT: Encina Siphon Inlet and Outlet Structure and the Ponto Pumping Station On 22 May 1975 a general inspection of the siphon inlet structure and the Ponto Pumping Station was made in your presence at the request of this depart- ment to review certain operational and maintenance problems. Later the siphon outlet structure was inspected by the writer for safety and maintenance purposes. These units belong to the City of Carlsbad, the Leucadia County Water District, the Encinitas Sanitary District, and at your request, have been operated by our staff since being completed. As a result of the inspections, which include a review of the facilities by the County Safety Officer, the following list of deficiencies is presented for correction as soon as possible: Siphon Inlet Structure 1. Provide and install corrosion resistant squirrel cage type blower suitable for continuous operation similar or equal to: American Blower Utility Set #l-k MJ, 430 cfm § %" W.C., 1140 rpm, 1/6 HP TEFL motor with overload protection, aluminum wheel, cast iron housing with interior and exterior coated with "Bisonite M", unit factory dynamic balanced insect screen on inlet, 115/230 volt single phase 60 hertz. Blower to be installed on top of structure so as to discharge into chamber through one of the existing vents. (Note: Power service to come from adjacent Ponto Pumping Station.) 2. Electrical a. Install Grouse-Hinds EVCX240 interior 100 watt ceiling light, ex- plosion proof, mounted with guard Class I GPD. b. Install switch for interior light on outside of structure at convenient location. Grouse-Hinds EDSC218-S602, 20 amp, 120 volt, 2 pole, Class I GPD, factory sealed. c. Install motor switch on outside of structure. Any brand, 2 pole, O.L. for motor, weatherproof. d. Install explosion proof conduit to serve light and standard conduit for all other wiring. • i Mr. Ron Beckraan City of Carlsbad Page 2 15 JUL1975 3. Install aluminum handrail with toe plate around top of structure. Approxi- mately 36 feet required. (2nd priority) 4. Remove MH rungs and install OSHA ladder or stairs of all aluminum con- struction. (2nd priority) Ponto Pump Station 1. Secure pump station making certain wet well does not cause odors. 2. It is not feasible to install a full flow valve on pump station inlet line running between manhole and wet well. The existing line is constructed of 8 inch V.C. %. Siphon Outlet Structure 1. Install blower and switch equal to unit specified for inlet structure. 2. Install power supply via buried conduit from near flow meter or blower house. To be determined by design engineer. 3. Provide electrical convenience outlet at structure. 4. Repair corroded hardware on Bilco hatch. 5. Install approximately 35 feet of aluminum handrail with toe plate around top. The cost for this work, including engineering and contingencies, is estimated to be between $5,000-$6,000. We recommend the work be properly engineered with suitable drawings and specifications and a minor form of contract be let. We hereby request your prompt attention in having all of this work accomplished. The execution of the agreement, presently in your hands, authorizing the County to operate and maintain these facilities should also be expedited. B. V. ELKINS Director (Acting) By C. B. OLDSEN CBO:si