By Mark Dupree 27 Jun, 2022
The 2015 Facility Plan developed a project scope for the Phase III expansion. At that time, the project included the addition of one raw sewage pump, upgrade of the biological process for expansion and removal of TN and TP, construction of an additional tertiary clarifier or construction of tertiary filters, upgrade of the aerobic digestion process, the addition of onsite sludge dewatering, and 150 days ultimate sludge storage capacity. Since 2015, the scope evolved due to the age of the equipment (originally installed in 2000) and changes in operational theory and preferences. The facility is currently permitted for a Design Average Flow of 0.7 MGD. The project will expand the DAF capacity to 1.05 MGD. With this expansion, new effluent requirements come into play due to anti-degradation requirements. The new facility will have the ability to biological remove total phosphorus, and total nitrogen, as well as improve the total solids removal. The project includes increasing the capacity of the raw sewage and RAS/WAS pump stations. The preliminary treatment screening structure was originally designed to handle 6 MGD through one channel with a bypass channel for future equipment. The existing screen will be replaced in-kind, and a 6 MGD perforated plate drum screen will be installed in the second channel for screening RAS and influent flows exceeding 5.23 MGD. The two existing aeration basins will be modified to include a 5-Stage biological nutrient removal (BNR) process. A third basin will be constructed to increase the WRF treatment capacity to 1.05 MGD. All basins will be fitted with baffle walls for zone separation, internal recycle pumps for denitrification, mixers for maintaining solids in suspension, and new fine-bubble diffusers for the aerobic and anoxic/swing zones. The existing centrifugal blowers will be replaced with positive displacement rotary lobe blowers, which will be controlled by Dissolved Oxygen (D.O) probes located in the aeration zone that will increase/decrease the blower speed to maintain the desired D.O. The existing tertiary clarifiers (600 GPM/SF surface overflow rate) which were constructed in Phase II will be downgraded to secondary clarifiers (1000 GPM/SF) in the Phase III project. The clarifiers will be rehabilitated with new drives, bearings, gear reducers, wear items, and control panels. To maintain tertiary treatment, a new Tertiary Building will be constructed and contain new disc filters, UV disinfection, a non-potable water booster system, and a backup chemical phosphorus removal system (alum) for the new BNR process. The proposed layout of this building is designed to allow the tertiary treatment capacity to double when flows to the Facility increase. The aerobic digestion facility will be upgraded as well, with a rehabilitated gravity thickener mechanism, new air header, and sludge piping modifications. The digestion complex will overflow to a digested sludge storage tank at the new Sludge Handling Building. In addition to the storage tank, this structure will contain a recycle pump station to convey wastewater/supernatant/pressate to the head of the Facility, sludge pumping, polymer feed systems, a protected water system, a belt filter press, and a belt sludge conveyor. The proposed layout of this building is also designed to allow the sludge handling capacity to double when loading to the Facility increases. The belt conveyor will carry dewatered sludge from the Sludge Handling Building out to the new Sludge Storage Building, a 34,000 SF concrete slab covered by a 3-sided pre-engineered metal building. This structure will provide the City with a year of storage for their biosolids from both the West Side WRF and the Main WWTF (9 MGD) located on the other side of town. A Vactor Receiving Station will also be constructed onsite, similar in design to the Sludge Storage Building. The project also includes water main extension, SCADA upgrades, removal of the existing drying beds and dewatered sludge storage area, drain tile realignment, and mass grading to facilitate overland flow and protect wetlands onsite and adjacent to the project. This project is funded through a low interest loan through the IEPA. Construction began in May of 2021.
By Mark Dupree 09 Jun, 2022
The City of St. Charles owns and operates a sanitary sewer collection system and two wastewater treatment facilities: The Main Wastewater Treatment Facility and the West Side Water Reclamation Facility. The collection system tributary to the Main Wastewater Treatment Facility (Main WWTF) consists of approximately 152 miles of sanitary sewers, 5 miles of force main and 13 lift stations. The Main WWTF is located at the Public Works Facility, 1405 S. 7th Avenue on the eastern shore of the Fox River. The treatment facility has a design average treatment capacity of 9 million gallons per day (MGD). The facility generally serves the community’s wastewater needs east of Randall Road and discharges to the Fox River. The facility provides preliminary, primary, and secondary treatment for flows received from the tributary communities to meet strict effluent water quality requirements before discharging to the Fox River. Trotter and Associates completed the Facility Plan and Phosphorus Removal Feasibility Study for the Main WWTF in 2015. The analysis recommended implementation of an A 2 O process to address the phosphorus limit and future Total Nitrogen requirements, a chemical feed system for polishing, a chemical buffering system for struvite prevention, and a primary sludge fermenter for enhanced BPR. The Facility Plan also identified the need for a Digester Improvements project. The existing anaerobic digesters were constructed in 1989. The previous digested sludge storage tank was constructed in 1951 and repurposed multiple times. The Facility Plan recommended rehabilitation of the anaerobic digesters and replacement of the digested sludge storage tank. It was further recommended that the project be completed jointly with the Phosphorus Removal Project to expedite the completion schedule and minimize disruption to treatment facility operations. Performing both projects in parallel led to process disruption throughout the plant. The contractor, engineering team, and City staff were in constant communication regarding shutdowns of various processes throughout the plant. Digestion was required throughout construction. Therefore, only one of the egg-shaped digesters could be emptied at a time for rehabilitation. After completion of the first digester, sludge was transferred to it so the second digester could be rehabilitated. Additionally, for the biological process work only 2 of the 8 process basins could be emptied at a time to maintain permit compliance. City staff worked with the engineer and contractor throughout construction to maintain permit compliance when a large percentage of their biological process was not available. The project was completed in July 2019, and through teamwork, constant coordination, and the dedication of all parties, the project was completed within 1.1% of the bid price, and below the original estimate for the two separate projects.
Batavia WWTF Phase I Rehabilitation
By Mark Dupree 04 May, 2022
The City of Batavia is located along the Fox River in southern Kane County, approximately 35 miles west of downtown Chicago. The City’s Wastewater Treatment Facility (WWTF) is located on Shumway Avenue on the western shore of the Fox River. The treatment facility has a design average treatment capacity of 4.2 million gallons per day (MGD). The facility provides preliminary, primary, and secondary treatment for flows received from the tributary communities to meet strict effluent water quality requirements before discharging to the Fox River. The Batavia WWTF was required to comply with a 1 mg/L phosphorus limit. It was likely that the treatment facility will need to achieve lower phosphorus effluent limits prior to 2030. In addition, the Batavia WWTF will require additional capacity in the near future and must be expanded to 4.9 MGD. This expansion triggers the anti-degradation portion of the 2004 IEPA nutrient removal criteria. Therefore, the expanded treatment facility must be able to perform nutrient removal for both nitrogen and phosphorus. This was analyzed with the 2014 Facility Plan and Phosphorus Removal Feasibility Study, which recommended a three-phased approach to meeting the needs of the WWTF. Phase I included rehabilitation of the excess flow disinfection system. The existing chlorine feed system was installed in 1989 within the Chlorine Building and was an operational challenge. The system was replaced with a liquid sodium hypochlorite delivery system, including chemical storage tanks and a duplex skid-mounted diaphragm pump feed system within the existing Chlorine Room. The finished floor of this building is below the floodplain of the Fox River, and this is particularly sensitive as the building contains the emergency back-up generator for the WWTF. Therefore, all entrances to the building were retrofitted with stop logs that may be installed during flood events. Chemical phosphorus removal was also implemented in the Phase I project. The chemical storage and feed systems were installed as a separate structure, including rammed-aggregate piers, retainage walls, base slab, two chemical storage tanks, and a climate-controlled enclosure for the pumping equipment. The chemical is fed within the effluent box of the Nitrification Basins to optimize mixing and capture of the phosphorus prior to settling in the final clarifiers. The Phase I Rehabilitation included the replacement of the Intermediate Pump Station. The design of the new pump station accounted for the tankage and hydraulics required by the existing biological process as well as the future hydraulic conditions from the Phase II Expansion. The Intermediate Pump Station was incorporated into the design of the new Digester Operations Building and contains four 100 HP submersible pumps in a dual wet well design. The City stabilizes biosolids with two 40-foot diameter anaerobic digesters. The Phase I Rehabilitation included replacement of both digester covers, the digester mixing systems, and the digester heating systems. The floating digester covers were replaced with spiral-guided, gas-holding covers to provide the City with nearly 12,000 cubic feet of digester gas storage. The new Main Building was constructed on land occupied by the existing Administration Building. That building housed the laboratory, administration offices, maintenance garage, and locker rooms. The new structure has 22,000 square feet of working space including a mezzanine within the new Maintenance Garage. The new building also contains administrative offices, laboratory, locker rooms, SCADA stations and the new main electrical service for the WWTF. This building also contains sludge dewatering operations, including digested sludge storage, centrifuge feed pumps, polymer feed systems, centrifugal dewatering equipment, dewatered sludge conveyors, and protected water systems. Due to the proximity of this building to downtown and nearby residences and businesses, the City also made a significant investment in odor control for the digested sludge storage and sludge dewatering areas.
By m. dupree 04 Oct, 2021
Trotter and Associates, Inc works with Michels Corporation to install Grouted Rammed Aggregate Piers utilized during the design and construction of the DuPage County Public Works Nordic Park Wastewater Treatment Plant Rehabilitation located in Itasca, IL. As part of the design process, aggregate piers were selected as a cost-saving foundation for two Tertiary Clarifiers and a RAS/WAS Pump Station due to the presence of an organic clay layer beneath the proposed mat foundation. This technology modifies the surrounding soil, increases bearing capacity and reduces settlement. Other options considered by the design team but ultimately were not utilized included undercutting the unsuitable soils layer, installation of steel pipes, and helical piles. The approximate 4,600 square-foot area required a total of 104 30-inch diameter aggregate columns to be installed to an approximate depth twenty-two feet below grade. After installation, load testing was completed to ensure the required capacities were met.  The process of installing the pier included using a thirty-inch diameter auger to predrill the proposed pier locations. Upon completion of the pre-drill, a depth vibrator was inserted into the hole. Aggregate and grout were fed into the hydraulic vibrator through a hopper and hose where it was compacted to densify the soil. The material was then inserted to construct the aggregate piers creating the grouted aggregate pier foundations for the two clarifiers and pump station. This method of construction is efficient, and all 104 piers were installed within 6 days. To see a video showing the process, please click on the following link: https://youtu.be/U6KYaJwK_u4
By m.dupree 20 Mar, 2018
The City of Crystal Lake contracted with Trotter and Associates, Inc. (TAI) to design and oversee the upgrades of a 2.3 MGD...
By m.dupree 11 Oct, 2017
Trotter and Associates, Inc. provided construction observation services to the Village of Algonquin for the construction of the Indian Grove Subdivision Roadway...
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