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Proven structural BMPs designed to efficiently and effectively treat stormwater by separating debris and trapping pollutants before they enter the waterways. All BaySeparators, both PT for pre-treatment and SA for stand-alone applications, can be fabricated into multiple sizing combinations to fit a variety of applications and custom installations.

FACT: An all-inclusive treatment train guarantees economy of scale, precise multiple sizing combinations, greater installation flexibility, and superior pollutant removal efficiencies. 

Specify BaySeparator

Both BaySeparator products (the PT, pre-treatment, and the SA, stand-alone) consist of two standard pre-cast manholes and the BaySeparator unit. The two manholes allow the removal and storage of pollutants, while BaySeparator directs the flow of water to provide the most efficient treatment possible. BaySeparators are customized to fit your specific project requirements and the diameter and depth of both the primary and storage manholes may be tailored to suit any specific site conditions necessary.

BaySeparator PT (Pre-treatment)


Designed specifically to function as the pre-treatment device when applied in a stormwater treatment train, BaySeparator PT allows for greater pollutant removal and increased efficiency down the line. It’s engineered to typically remove 50% of the suspended solids on an annual aggregate removal basis, or other required methodology, from stormwater prior to the next BMP in the “train’s” succession, such as BayFilter.

BaySeparator SA (Stand-alone)


BaySeparator SA is Hancor's latest stand-alone version that meets, or surpasses, all industry standards and regulatory 80% TSS removal requirements. Typically installed as a stand-alone, the SA efficiently removes suspended solids, hydrocarbons and floatable debris.

Easy Installation

The BaySeparator is installed as part of the storm drain. To begin, grout the BaySeparator unit and the system inlet pipe into the primary manhole. Alternatively, use a watertight seal where local regulations specify.

The parallel pipes entering and leaving the storage manhole require watertight connections – these are made by using standard boots or other seals. Flexible watertight couplers join BaySeparator to the parallel inlet and outlet pipes from the storage manhole. These flexible seals prevent system failure in the event of differential settling between the two concrete structures. Cover the pipes with gravel or any type of flowable fill. Complete your final backfill and the BaySeparator is ready to start operation.


View BaySeparator Animation (Click here)


Easy Inspection. Easy Maintenance.

One of the advantages of BaySeparator is that its design offers unobstructed access for pollutant inspection and removal. By opening either manhole cover, trapped pollutants can easily be seen from the surface, making confined space entry unnecessary. Inspection can be performed through visual observation and by measuring sediment levels.

Normally when the accumulated sediments in either structure reach a height of two feet from the manhole floor, maintenance should be performed on the system.

The maintenance cycle typically falls into an annual pattern given normal loadings and sizing. Inspection of the system is recommended quarterly for the first year or more to determine the appropriate cycle based on site characteristics.

Four Easy Steps to Maintaining BaySeparator


The first step involves quarterly inspections and possible maintenance of each BaySeparator you have installed. All permits issued by the National Pollutant Discharge Elimination System (NPDES) require an MS4 to ensure adequate long-term operation and maintenance of all BMPs per EPA rule §122.34(b)(5) of the Clean Water Act. This ruling simply means that every BaySeparator must be inspected and/or maintained on a scheduled basis. BaySeparator, like any other BMP, must be inspected quarterly and maintained yearly, or more frequently if there is evidence of a chemical spill, more than two feet of sediment has accumulated, or there is a significant amount of oil noticeable in the unit.

Scheduled maintenance ensures that your BaySeparator system will continue to function correctly and efficiently, yielding optimum performance and retaining maximum value.


It's easy to save money after installing BaySeparator. We have pre-negotiated a reduced rate with several storm sewer maintenance service providers. We will assist you in getting the best possible price from them and then forward the contract to you. All that is left for you to do is fax the contract back or mail it to Hancor, Inc.


By choosing BaySeparator from Hancor you’ve assured yourself of installing a stormwater treatment system that complies with every measure of Phase II (§122.34(b)(5)) of the Clean Water Act.

The Clean Water Act is the primary Federal statute governing the restoration of our nation's waterways. Phase II (§122.34(b)(5)) of the Clean Water Act states that all MS4 regulated entities building after March 2003 must implement a plan to treat stormwater runoff. This includes maintaining the BMP treatment solution. To do otherwise, even in ignorance, may invite the possibility of large fines and penalties.


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