AKM is currently providing construction management, inspection, and design quality control services for the City of Long Beach’s Municipal Urban Stormwater Treatment (LB-MUST) Facility. This innovative project is designed to intercept non-stormwater runoff and capture a portion of the first-flush storm flows from the City’s urban watersheds before they reach storm drain outfalls that discharge into the Los Angeles River and its estuary. The system features multiple upper watershed diversions located along existing storm drains, with small pump stations installed at each diversion to collect and redirect flows. Additional flows are diverted from existing stormwater pump stations via their sump pumps, and a network of hydraulic conveyance systems—including pipes and open channels—delivers the captured runoff to a downstream advanced treatment facility. This facility includes a combination of treatment technologies, constructed wetlands, and storage basins, with the added potential of serving as a future alternative water supply source. The project is being implemented in three phases: site clearing and preparation (including underground utilities and ground stabilization), construction of the treatment facility, and construction of the conveyance systems.

LB-MUST Street Improvements (completed 2018)

AKM provided construction management and inspection for this phase, which included clearing and grubbing of the proposed site, initial rough grading of the site, removal of buried railroad tracks and ties, installation of K-rail and fencing around the site, establishment of long term stormwater best management practices (BMPs) for the disturbed area and weekly BMP inspections. The work also required the City to relocate a homeless encampment within the work zone. In 2020, AKM provided construction management services for Phase II of the program which included the construction of a new low voltage electrical service, reconstruction and realignment of the roadway fronting the proposed treatment plant site, underground utilities such as water, storm drain and recycled water, as well as the installation of 3,100 linear feet of the conveyance pressure pipe system.

LB-MUST Ground Improvements (completed 2021)

AKM oversaw ground improvement work, which included furnishing all plant, labor, equipment, and materials; performing all operations as required to construct the deep soil mixing (DSM) ground improvements; and providing all associated testing, monitoring, sampling, and recording. Specific work included: mobilization/demobilization; SWPPP; excavation and placement of 2 stockpiles; disposal of hazardous soil; surveying; Deep Soil Mixing construction in full compliance with bid documents; quality control; and construction of a load transfer platform

LB-MUST Treatment Plant and Wetlands

AKM provided quality control and constructability review for the 90% design package of the LB-MUST treatment plant and conveyance system and is currently managing construction and inspection during implementation. The treatment plant is designed to process both brackish and non-brackish influent flows through separate treatment trains. The treatment process consists of influent strainers, ceramic membrane ultra-filtration (UF), and an advanced oxidation process (UV/AOP). Additional processes include pumping, storage tanks, chemical feeding, and air supply systems. The facility has also been designed to allow for the future addition of a reverse osmosis (RO) system to reduce TDS levels and provide additional barriers for potential potable reuse applications. The ceramic membrane system, which consists of two 1-million-gallon-per-day (MGD) units, as well as the UV/AOP system, was pre-purchased by the City. The treatment facility will be housed in a 9,000-square-foot cement masonry unit building, which will include electrical, chemical, and control rooms, as well as an HVAC and mechanical system. As part of the LB-MUST project, a new wetlands area and pedestrian walking path are being constructed. This portion of the work includes the demolition of an existing light industrial warehouse and associated structures, grading and excavation for the wetlands, installation of an impermeable liner at the wetlands bottom, and construction of reinforced concrete inlet and outlet structures with sluice gates. Additional work involves relocating utilities, installing pedestrian pathways around the wetlands, and upgrading the stormwater pumping system within the existing SD-02 Pump Station. The demolition activities included abatement and removal of the existing warehouse, appurtenant structures, parking lot, and interfering portions of utilities and infrastructure. Pump station improvements involved installing a submersible sump pump, new piping, valves, electrical work, and instrumentation to enhance operational efficiency.