MUNICIPAL ENGINEERING

Trotter and Associates, Inc. (TAI) currently provides municipal engineering services to over thirty (30) units of local government in northeastern Illinois, either as the appointed Engineer or as the consulting engineer.



As the appointed engineer, TAI is the designated firm in providing day to day general consultations, grant writing and project funding assistance, meeting attendance and project coordination, subdivision and development plan reviews, storm water reviews, GIS services, land surveying, capital improvement planning, design and construction services.


TAI has assisted clients in completing revisions and updates to engineering standards and the following municipal ordinances: subdivision; sewer uses; water use; wastewater pretreatment; zoning ordinances.


Through working for both large and small communities, Trotter and Associates recognizes that the needs are different from one community to the next. TAI understands the level of scrutiny that government agencies face and strive to assist its clients in keeping projects on schedule and within budget. TAI is diligent in the preparation of preliminary opinions of probable cost to ensure that our clients do not encounter the dilemma of addressing cost overruns during the construction phase of a project.


Trotter and Associates’ engineers understand that project costs are best controlled by preparation of detailed and accurate contract plans and specifications. Our designs routinely undergo a constructability review by our construction engineers during the Phase II design process to identify any potential cost or time-saving measures. This internal review allows us to make necessary design revisions prior to bid letting. TAI brings a commitment to detail and clarity in the preparation of plans and specifications that conform to municipal standards. Over the years, TAI has been very successful in minimizing change orders during construction resulting from in-depth assessments of local conditions.


TAI is very familiar with the problems brought on by aging infrastructure and the challenges faced by continued community growth. Trotter and Associates, Inc. has the experienced professional staff and procedures to improve the community’s infrastructure correctly, as well as in a cost effective manner by providing the best solutions possible.


Trotter and Associates’ goal is to provide the best possible service to all of our clients. In order to support this goal, TAI has assembled an experienced team of engineers, surveyors, engineering technicians, and support staff that is committed to providing the most efficient, cost effective, reliable solutions to our clients.



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RELATED PROJECTS

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. The St. Charles Main 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. Trotter and Associates completed the Facility Plan and Phosphorus Removal Feasibility Study in 2015. The analysis utilized BioWin™ to evaluate various treatment methods and technologies. The selected alternative was an A 2 O process to address the phosphorus limit and future Total Nitrogen requirements. The recommendations also included construction of a chemical feed system for polishing, a chemical buffering system for struvite prevention, and a primary sludge fermenter for enhanced BPR. The 2015 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.
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.
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