Streams Tech, Inc. (STI) prepared a guidance document for developing bacteria Total Maximum Daily Loads (TMDLs) for the Virginia Department of Environmental Quality (DEQ) providing the details of potential data sources, data pre-processing methodologies, multi-year hydrologic and water quality model setup, development of TMDL allocations and addressing regulatory requirements to standardize the TMDL development process and the deliverables. Approximately 650 bacteria TMDLs have been developed in Virginia using a detailed approach in quantifying point and nonpoint bacteria sources, developing allocations and planning implementations.
Streams Tech, Inc. developed bacteria TMDLs for waterbodies occupying 137 square miles of Prince William and Stafford Counties in Virginia and predicted water quality conditions using an HSPF model under a variety of rainfall and bacteria loading scenarios.
STI delineated the watershed into smaller subwatersheds by topography and hydrologic connectivity, presenting descriptive data on each subwatershed and stream segment by developing calibrated and validating hydrologic water quality models and developing allocation scenarios. The developed model accounted for point and nonpoint pollutant discharges in the watershed, and results were used to determine effective TMDL allocations. The EPA approved of the TMDL in 2013.
Streams Tech, Inc. developed a watershed model using BASINS/HSPF for Hyco River, which flows from North Carolina into Virginia, and performed initial model setup (e.g. BASINS/HSPF setup, watershed delineation, land use reclassification, FTable generation), weather data and WDM file preparation, hydrologic and water quality calibration and validation of the model for Michael Baker Jr., Inc.
The project involved an eight year simulation of flow and pollutant concentrations on an hourly basis at various locations to determine the assimilative capacity of stream reaches and was used to develop TMDL allocations for various impaired reaches of the watershed.
A stormwater collection system model was developed to identify problems in the existing stormwater infrastructure of Fort Bliss and find effective solutions to frequent flooding during summer storms. This was done using EPA's SWMM data, Geographic Information System (GIS) data calibrating with observed, site-specific flow and storm data, AutoCAD images of the sewer network, historic data, and data from surveys conducted on-site along with LIDAR survey data.
The model was also used to demonstrate the system's effectiveness in design storms, providing insight as to how it would perform in a variety of rainfall scenarios.
The Four Mile Run Watershed is one of the most heavily urbanized drainage basins in Northern Virginia, encompassing lands from four jurisdictions. Streams Tech, Inc. provided technical expertise to the Northern Virginia Regional Commission on hydrology, hydraulics, stormwater management, and water quality issues in support of the Four Mile Run Watershed Management Program. An existing model has been updated to EPA's SWMM 5 incorporating latest storm sewer system data, in addition to dealing with other floodplain issues of the system.
In coordination with Halcrow, Inc. team, STI provided on-call services to Southwest Florida Water Management District (SWFWMD) under the Peer Review of Floodplain Results contract.
A peer review was performed, which addressed the reasonableness of modeling and results used to update the floodplain delineations as part of the District’s Cooperating Technical Partner (CTP) responsibility to provide accurate digital flood maps.
Streams Tech, Inc. developed a comprehensive water distribution and management system model for McAlester, Oklahoma that simulated pipe flow hydraulics, such as dynamic flow rates and pressures throughout the distribution system.
The model helped to evaluate the existing water networks, optimizing the flushing program, and assess the current capacity and performance of the distribution system at any location. This could be used to plan for expansion (such as optimal sizing of new water main), potential locations for new towers and pumps, and other future development.