Standard STS Configuration
The following four images are examples of standard configurations or typical site plans for the StormTreat System. These drawings are not to be used for construction, but to provide some common options for configuring the system. Please take a few minutes to study and read through the descriptions. For a larger view, click this link to open all four pages as a pdf: Standard Configuration PDF.
First off, it's important to note that the majority of projects dealing with stormwater require treatment of a minimum quantity of the total runoff, known as the water quality volume (WQV). Therefore, the following four "Cases" include detention systems (proprietary and conventional), external from the capacity inside of the STS units, that are sized to detain a volume equal to one-inch of rain on a one-acre impervious surface (about 3630cf). This configuration is often referred to as an "end of treatment train" approach, where catchment, pretreatment and detention are all upstream of the STS. This configuration is sized, using a volume based approach, to detain and treat the WQV.
Case # 1: Closed Pipe Storage (sheet 1 of 4)
This first option presented utilizes 36-inch diameter, corrugated, polyethylene pipe, prefabricated to function as a watertight detention system. Influent stormwater enters on the far left via the flow splitting manhole and proceeds through the detention system, STS units and exits via the outlet structure on the far right. Note: We can recommend shops where these systems can be custom fabricated for your project.
1. Capable of capturing and treating any volume necessary without losing any untreated stormwater to infiltration.
2. Preferable in sensitive areas, and/or areas with high pollutant loads where immediate health concerns for humans, wildlife and the environment exist (ie. coastal areas, near water supplies, transfer stations, industrial areas, etc.)
3. Outlet valve can be shut to contain spills consisting of hazardous materials and can be pumped from detention and STS units.
4. Assures STS wetland plants get watered with every storm event (no infiltration loss).
5. Prefabricated nature allows for less involved installation than proprietary systems that generally require a concrete base, layers of stone, geotextile fabrics, liners, etc.
1. May be slightly more costly than other options due to custom fabrication of detention system.
2. May increase pollutant load to STS units resulting in increased necessity to pump systems out.
Capable of providing more detention per area as
Backfill Detention / Infiltration / Recharge
The excavated area surrounding the footprint of the STS units can be utilized as a detention and /or infiltration area.
Additionally, there are certainly instances where STS units can be installed without an external detention system. For example, when the WQV is small, the processing rate combined with detention volume available within the STS units and contributing pipe is adequate to meet quantity requirements. Or, when an LID approach is desired, the STS units can be placed sparsely throughout the site with little or no detention. Advantages of this approach are a smaller excavated footprint (LID), less expensive due to omission of detention system and more flexibility on placement of units throughout the site.