The URL can be used to link to this page

Home My WebLink AboutCOM 0428.003 1998-2000 OJP1Y O! N,k~i 4.'~'-. - tip.;: Stephen K Yamashiro Mayor • , Jiro A. Sumada N•:• !'r y: ' Dryuly Chie~Engi~rr ••O. M~ u Cnuixntg of ~ttflrttii ° •1 T DEPARTMENT OF PUBLIC WORKS ~ ~ ;7 25 Aupuni Sveet, Room 202 • Hilo. Hawaii 96720.4252 ~ February 24, 2000 608)961-8321 • Fax (808)961-6630 Memo OOLH-027 T. Thomas E. Arizumi, P.E. Chief, Environmental Management Division State Department of Health P.O. Box 3378 Honolulu, Hawaii 96801 Subject: Hilo Wastewater Treatment Plant Operation and Maintenance Inspection - EMDNVB 200022 Reference: (a) County of Hawaii Department of Public Works letter dtd. 7/14/99, Hilo Wastewater Treatment Facility O&M Inspection - EMDNVB 971337, Corrective Action Plan (b) County of Hawaii Wastewater Division letter 99LH-110 dtd. 10/11/99, Chlorine Contact Detention Time -Hilo Wastewater Treatment Plant (EMD/WB 990435) (c) Dept. of Health Letter EMD/WB 200038 dtd. 1/24/2000, Chlorine Contact Detention Time and Automatic Flow Proportional Chlorination System, Hilo Wastewater Treatment Plant The County of Hawaii Wastewater Division has received the annual Operation and Maintenance Inspection Report for the Hilo Wastewater Treatment Plant and provides the following corrective action plan to address the deficiencies cited in the report. Maintenance: 1. Primary Clarifier No. 1 -Malfunctioning VFD. Subsequent to the County of Hawaii's response to the 1998 Operation and Maintenance Inspection Report (EMD/WB 971337), the Wastewater Division contracted a Design Consultant to perform a comprehensive facility review. Preliminary recommendation is that the pump should be replaced (versus repair of VFD) to provide redundancy for the DAFT which is currently being utilized as a gravity thickener. Target completion date for replacement of the pump is March 2001. I' Comm. No. `t'2S• ~3 Ftile No. SE~ Ref. To: ~1q/PG Ref. Date FEB 2 9 2000 Memo OOLH-027, Hilo WWTP 1999 OSM Response Page 2 of 6 2. Grit screw -Rebuild screw and replace housing. The grit screw housing has been repaired. Rebuilding of the grit screw is deferred since the County of Hawaii intends to replace the existing grit classifiers. Existing wear of the grit screw does not affect performance of the grit classifier since the screw is used to transfer settled grit to the grit hopper. Target wmpletion date for replacement of the grit classifiers is March 2001. 3. Aeration Tank Diffusers -Needs replacement. A comprehensive facility review has been performed by a design consultant. Preliminary evaluation of the consultant firm indicates that Pre-aeration tanks are not required due to the low loading rates to the facility. As such, repair of the Pre-aeration diffusers is deferred pending final recommendation by the consulting firm. 4. Centrifuge No. 1 -Tiles are falling off. As per reference (a), the Wastewater Division has had several discussions with the equipment manufacturer (Humbolt-Decanter) regarding the loss of tiles. Operation of the centrifuge is not affected and repair of the centrifuge is deferred until such time that efficiency of the unit is adversely affected. 5. Biotower Pump No. 2 and 4: Biotower Pump No. 4 has been repaired and is in service. Repair to Biotower Pump No. 2 is deferred since the Wastewater Division will be replacing Biotower Pumps No. 2 and 3 with Vertical Turbine Solids Handling Pumps due to their ability to better withstand existing conditions (pumping of Primary Clarifier effluent). Target Completion date for replacement of Biotower Pumps No. 2 and 3 is December 2000. 6. Final Clarifier No. 1 - No Skimmer Arm The Wastewater Division issued a Notice to Bidders for a contract to replace the skimmer arm assembly in November 1999. No bids were received for the repair work. The Wastewater Division will re-issue the bid package for repair of the skimmer arm assembly. Target Completion date for repair of the Skimmer Arm Assembly is October 2000. Memo OOLH-027, Hilo WWTP 1999 O&M Response Page 3 of 6 NPDES or Chanter 62 Violations: 1. The 85 percent BODS removal rate was not met for the months of October and December 1998 and March, April, and May of 1999. GODS removal rates are affected by the low BODS influent readings. Effluent BODS readings are within limits specified in the NPDES Permit for the Hilo Wastewater Treatment Plant. 2. The Chlorine Residual limits were exceeded during the months of February and May of 1999. As per reference (b) a Flow Proportioned Chlorination system has been installed at the Hilo Wastewater Treatment Plant, which should aid in controlling Chlorine Residual limits at the effluent facility. Facility's Present Deficiencies: 1. Infiltration/Inflow (I/I) continued to impact plant operations as noted by the low influent BODS/TSS readings. As noted in reference (a), the Wastewater Division utilizes Grout Sleeve equipment and is in the process of procuring Chemical Grouting equipment to aid in reduction of I/I. Reduction of I/I is an on-going program. 2. Primary Clarifier No. 1 has been inoperable since 1995 due to a malfunctioning VFD. Co-settling mode of operation requires two of the three clarifiers to be on- line at all times. As per Maintenance item no. 1, the Wastewater Division contracted a Design Consultant to perform a comprehensive facility review. Preliminary recommendation from the consulting firm is that the pump should be replaced (versus repair of VFD) to provide redundancy for the DAFT which is currently being utilized as a gravity thickener. Target completion date for replacement of the pump is March 2001. With regard to the requirement that two of the three clarifiers be on-line at all times, the Wastewater Division utilized one (1) Primary Clarifier for the period of January 24, 2000 to February 8, 2000 after installation of new VFD's at the Pua Sewage Pumping Station since stable influent flow was achieved with the new Pua VFD's. Process control data from use of the single Primary Clarifier indicated that Primary Clarifier TSS and BODS removal rates remained in their normal ranges. In addition, superior plant efficiency (increased BODS and TSS removal rates) was achieved when utilizing a single Clarifier. Memo OOLH-027, Hilo WWTP 1999 O&M Response Page 4 of 6 3. The diffusers for the Pre-aeration basin required replacing due to plugging problems. As per Maintenance item no. 3, a comprehensive facility review was performed by a design consultant. Preliminary evaluation of the consultant firm indicates that Pre-aeration tanks are not required due to the low loading rates to the facility. As such, repair of the Pre-aeration diffusers is deferred pending final recommendation by the consulting firm. 4. Biotower Pumps No. 2 and 4 were inoperable awaiting repairs. As per Maintenance item No. 5, Biotower Pump No. 4 has been repaired and is in service. Repair to Biotower Pump No. 2 is deferred since the Wastewater Division will be replacing Biotower Pumps No. 2 and 3 with Vertical Turbine Solids Handling Pumps due to their ability to better withstand existing conditions (pumping of Primary Clarifier effluent). Target Completion date for replacement of Biotower Pumps No. 2 and 3 is December 2000. 5. The bent skimmer arm for final Clarifier No. 1 still requires replacement. As per Maintenance Item No. 6, the Wastewater Division issued a Notice to Bidders for a contract to replace the skimmer arm assembly in November 1999. No bids were received for the repair work. The Wastewater Division will re-issue the bid package for repair of the skimmer arm assembly. Target Completion date for repair of the Skimmer Arm Assembly is October 2000. 6. The Waste Gas Burner was not being used because it does not re-light automatically when the flame goes out. This is incorrect. The Waste Gas Burner is utilized although automatic re- ignition is not available. Re-lighting of the Waste Gas Burner is accomplished manually. Modification of the Waste Gas Burner system to provide automatic re-ignition will be accomplished as part of the design consultant's facility review. Target Completion date is March 2001. 7. The tiles for Centrifuge No 1 still requires replacement. As per reference (a) and Maintenance item no. 4, the Wastewater Division has had several discussions with the equipment manufacturer (Humbolt-Decanter) regarding the loss of tiles. Operation of the centrifuge is not affected and repair of the centrifuge is deferred until such time that efficiency of the unit is adversely affected. Memo OOLH-027, Hilo WWTP 1999 08M Response Page 5 of 6 8. The electrical conduits in the primary MCC room still have not been painted. The electrical conduits have been painted. Completed. 9. During the inspection, Boiler No. 1 had malfunctioned and was placed out of service. Repair of Boiler No. 1 is complete and the boiler is in service. 10. Bacterial sampling results for the effluent are suspect to the lack of adequate detention time in the chlorine contact tank. As per reference (c), the Department of Health has approved use of the detention time in the effluent line in determining the total Chlorine Contact Period. 11. The automatic flow proportioned Chlorinator remained inoperable. As per reference (b), the automatic flow proportioned Chlorination system was installed in October 1999 and is operational. 12. Staff vacancies continue to impact preventive and corrective maintenance work at the Hilo WWTP. The Mechanics position is currently filled. In addition, a Mechanical Repairer's position has been permanently filled and a temporary Assistant Wastewater Treatment Plant Operator's position has been filled. As per reference (a), a final resolution for the WTP Supervisor's position is targeted for 6/30/00. 13. The sewer user charge still appears to be inadequate to cover annual operation and maintenance costs of the facility. As per reference (a), the Wastewater Division will be proposing revisions to the Hawaii County Code to increase user rates. Target Completion Date is 6/30/00. 14. The equipment replacement fund for FY 98/99 showed a balance of $1,909,172 on June 30, 1999. Considering all of the equipment problems noted above, a $150,000 disbursement during the fiscal year is questioned. As per reference (a), the County has created a new CE V position within the Wastewater Division to assist in designing and/or contracting the necessary equipment upgrades or replacement work and currently has a consultant firm to assist in accomplishing repairs as well as to perform a comprehensive facility review. Memo OOLH-027, Hilo WNfrP 1999 O&M Response Page 6 of 6 15. A discrepancy concerning the process control data for the Biofilter influent was noted. It was determined that the sampling location of the influent was not representative of the wastewater entering the Biofilter. The process control sample point has been moved in order to obtain a more representative sample of the wastewater entering the Biofilter. Should there be any comments or questions on the above please contact Peter Boucher, Division Chief at 808-961-8338 or correspondence can be sent via facsimile to 808-961-8644. Sincerely, q~Jir A. Sum da Dep Chi f Engineer cc: Councilman Dominic Yagong, Public Works Chairman D. Yamamoto C. Dawrs, DRC