I. Case Background: From Pilot to Full-Scale Implementation In early 2022, the municipal sanitation department of a district in Linfen City, Shanxi Province, launched a special sludge removal and transportation improvement initiative. Annual sludge volume generated from local wastewater treatment plants and pipeline desilting operations has been steadily increasing. The existing small-capacity dump trucks (6 m³ and 8 m³) were no longer sufficient to meet transportation demands—suffering from low efficiency and poor sealing, resulting in frequent secondary pollution. Following multiple rounds of market research and technical comparisons, the department decided to procure a batch of 24 m³ sealed sludge dump trucks for closed-loop transportation of sludge from treatment plants to designated disposal sites. In the initial procurement phase, the unit selected Chengli Special Purpose Vehicle Co., Ltd.’s SINOTRUK-based 24 m³ sludge dump trucks via public tender, ordering five units with a total budget capped at approximately RMB 1.371 million (per publicly available tender information). These vehicles feature SINOTRUK HOWO chassis, with upper-body structures independently designed by Chengli—fully sealed dump bodies equipped with hydraulic lifting systems and a cargo capacity of 24 m³, compliant with China VI emission standards. II. Operational Performance: High Efficiency, Excellent Sealing, Low Failure Rate After nearly two years of real-world operation, the initial five vehicles have collectively accumulated over 150,000 km in mileage and transported more than 60,000 tons of sludge. According to feedback from the unit’s fleet management supervisor, the vehicles have demonstrated outstanding performance in the following areas: • Superior Sealing Performance: Fully sealed body design with hydraulically locked rear doors ensures zero leakage or dust emission during transport—effectively eliminating environmental complaints related to sludge transportation. • High Loading/Unloading Efficiency: Responsive hydraulic lifting system with large lifting angle enables clean, rapid unloading—reducing per-trip loading/unloading time by approximately 40%. • Excellent Chassis Stability: Powerful SINOTRUK chassis delivers robust performance under heavy-load conditions—including stable hill climbing and cornering—with low failure rates; critical components comply with OEM joint warranty standards. • Prompt After-Sales Service: Chengli provides lifetime after-sales support for the superstructure, while the chassis benefits from nationwide warranty coverage. Spare parts are shipped within 24 hours, and local service stations have conducted multiple on-site visits to resolve minor issues—ensuring uninterrupted daily operations. These tangible performance outcomes earned high recognition from the procuring entity and laid a solid foundation for subsequent contract renewals. III. Contract Renewal: Expanded Procurement in 2024 In early 2024, the municipal sanitation department issued a new procurement notice, planning to acquire an additional eight 24 m³ sludge dump trucks—continuing with the SINOTRUK chassis solution. Per local procurement practice, the total budget was capped at approximately RMB 2.285 million (per publicly available tender information), with an estimated unit price of around RMB 250,000. Chengli Special Purpose Vehicle participated again in the bidding process and secured the order based on its strong prior user satisfaction, comprehensive after-sales commitments, and transparent, competitively priced configurations. Compared to the initial 2022 procurement, the 2024 renewal contract incorporated the following improvements: • Upgraded Chassis Configuration: Newly ordered vehicles adopted the SINOTRUK HOWO TX series chassis, with engine power increased to 350 hp—better suited for more complex transportation routes. • Enhanced Superstructure Details: Based on field feedback, rear door sealing rubber strips were thickened, and an anti