Massachusetts Stormwater Technology Evaluation Program Evaluating Stormwater BMPs Spring 2013

The University of Massachusetts Water Resources Research Center works with MassDEP under a contract funded by the Federal 319 grant program to evaluate performance studies of stormwater treatment best management practices (BMPs). The database is found on the MASTEP web site www.mastep.net Massachusetts Stormwater Technology Evaluation Project, UMass

Stormwater treatment has two primary objectives: address water quality – i.e. reduce flood flows

And water quality: treat pollutants contained in stormwater. There are systems profiled on the MASTEP site that address either or both (water quality and quantity), but the majority of BMPs are designed to treat water quality.

Sediment is the primary stormwater pollutant regulated in Massachusetts. It is important because of its negative impacts to health of receiving waterways; Because it is associated with other pollutants that cling to it or bond with it; And because it is relatively easy to measure, making it a good surrogate when monitoring stormwater pollution.

Particle size is important: Because smaller sediment sizes are more effective at holding other pollutants like nutrients; Because smaller sediments take longer to settle out, hence are harder to treat.

Many BMPs are designed to slow moving water down, to give sediments time to settle out.

Filtering is another common way to treat sediments: some BMPs use vegetation or other media to filter or trap water and pollutants it contains.

Constructed Wetlands Removal Efficiency: 65-80% average 80% MassDEP TSS Removal Credit Key Features: Large area Peak flow control Biological treatment Maintenance: low to moderate Cost: marginally higher than wet ponds Advantages: Relatively low maintenance costs High pollutant removal efficiency Enhance aesthetics Disadvantages: Large land requirements Until vegetation is established, lower pollutant removal efficiencies High construction costs http://www.txnpsbook.org, 2002 Source: MassDEP, 2008. Massachusetts Stormwater Handbook

Extended Detention Basins TSS Removal Efficiency: 60-80% average 50% MassDEP TSS Removal Credit Key Features: Large area Peak flow control Maintenance: low Cost: low to moderate Advantages: Least costly BMP that controls both quantity and quality Good retrofitting option for existing basins Removes TSS and sorbed pollutants Beneficial habitat Less hazards than permanent pools Disadvantages: Infiltration is negligible Removal of soluble pollutants minimal Moderate to high maintenance requirements Potential contributor to downstream warming Potential sediment resuspension after large storms Source: MassDEP, 2008. Massachusetts Stormwater Handbook

Water Quality Swales Removal Efficiency: 65-805 average 70% MassDEP TSS Removal Credit Key Features: Higher pollutant removal rates than drainage channels Transport peak runoff and provide some infiltration Maintenance: low to moderate Cost: low to moderate Advantages: Control peak discharges by reducing runoff velocity and promoting infiltration Provides pretreatment by trapping sediments Generally less expensive than curve and gutter systems Disadvantages: Higher degree of maintenance than curb and gutter systems Subject to damage from off-street parking and snow removal http://www.txnpsbook.org, 2002 Source: MassDEP, 2008. Massachusetts Stormwater Handbook

Deep Sump Catch Basins Removal Efficiency: Design Features: 9-35% average 25% MassDEP TSS Removal Credit Design Features: Debris removal Pretreatment Maintenance: moderate to high Cost: low to high Source: MassDEP, 2008. Massachusetts Stormwater Handbook

Innovative BMPs – Media Filtration Removal Efficiency: 50-80% average Design rate: case by case evaluation Design Features: small area Oil and Grease control Maintenance: moderate Cost: moderate Filtration units force water through various media to trap sediments. Stormwater Management Inc, 2002 Massachusetts Stormwater Technology Evaluation Project, UMass

Innovative BMPs - Hydrodynamic Removal Efficiency: No treatment to 35% Design rate: case by case evaluation Design Features: small area Oil and Grease control Maintenance: moderate Cost: moderate Vortechs Inc, 2002

TARP- Technology Acceptance Reciprocity Program Address technology review and approval barriers in policy and regulations; Accept the performance tests and data from partner’s review to reduce subsequent review and approval time; Use the Protocol for state-led initiatives, grants, and verification or certification programs; and Share technology information with potential users in the public and private sectors using existing state supported programs CA IL MA MD NJ NY PA VA TX

Performance Verification - TARP Storm Event Criteria to Sample More than 0.1 inch of total rainfall. A minimum inter-event period of 6 hours, where cessation of flow from the system begins the inter-event period. Obtain flow-weighted composite samples covering a minimum of 70 % of the total storm flow, including as much of the first 20 % of the storm as possible. A minimum of 10 water quality samples (i.e., 10 influent and 10 effluent samples) should be collected per storm event. Determining a Representative Data Set At least 50 % of the total annual rainfall must be sampled, for a minimum of 15 inches of precipitation and at least 15, but preferably 20, storms. Massachusetts Stormwater Technology Evaluation Project, UMass

Performance Verification - TARP Stormwater Sampling Locations Sampling locations for stormwater BMPs should be taken at inlet and outlet. Sampling Methods Programmable automatic flow samplers with continuous flow measurements should be used Grab samples used for: pH, temperature, cyanide, total phenols, residual chlorine, oil and grease, total petroleum hydrocarbons (TPH), E coli, total coliform, fecal coliform and streptococci, and enterococci. Stormwater Flow Measurement Methods Primary and secondary flow measurement devices are required.

Is There Enough Data? Lab Studies Field Studies 15 test runs 15+ storms 15 inches of rainfall These slides illustrate the different criteria used when evaluating field and laboratory studies to determine whether they meet TARP requirements for field studies – or if lab studies, provide data of essentially equivalent quality.

Are the Data Representative? Weather conditions Topography, land use Soils, sediments By representative, we mean do studies produce or evaluate conditions typically found in stormwater; and/or expected to be encountered at the location where a particular BMP is to be installed.

Storms can produce highly variable flow patterns, and differences in concentrations of pollutants. Does a study capture such variability? Massachusetts Stormwater Technology Evaluation Project, UMass

Massachusetts Stormwater Technology Evaluation Project, UMass

Massachusetts Stormwater Technology Evaluation Project, UMass

Massachusetts Stormwater Technology Evaluation Project, UMass

Are the Data Representative?, Weather, Flows Multiple samples per event Field Studies: must include high flow/intensity storms Consecutive storms Sample all year Lab Studies: Flow rates: 25%, 50%, 75%, 100%, 125% Performance studies should test flows that are typical of local stormwater patterns, and that approach or exceed the capacity of the system – i.e. test the system under extreme conditions.

Data from a laboratory test. Column at left shows flows from 25% to 125% of system capacity. Column at right shows sediment removal efficiency at each flow. For this system higher flows resulted in lower treatment efficiency.

A system does not have to achieve high treatment efficiency (e. g A system does not have to achieve high treatment efficiency (e.g. 80% TSS removal) at all flows. Systems are evaluated on an annual basis. This table shows the calculation used by New Jersey for laboratory tests. Each flow is given a weight factor, that is roughly based on the expected frequency of storms of that size on an annual basis. Larger storms are encountered less frequently than are small storms. This is a simplification of rainfall distribution frequencies found in the field.

For each flow, the tested % removal is multiplied by the weight factor For each flow, the tested % removal is multiplied by the weight factor. Add the results for each flow to get an overall performance rating for the system.

Are the Data Representative? Sediment Sediment size is important. It is easier to treat large particles. A wide range of particle sizes, from sand to silt and clay, is generally preferred in performance studies. TARP-recommended influent sediment concentrations of 100-300 mg/l are meant to reflect typical concentrations found in stormwater. Higher concentrations, or dirtier flows, are generally easier to “clean” (i.e. attain a given removal %) than are lower concentrations. Particle size: mean < 100 microns; distribution 55% sand, 40% silt, 5% clay Influent concentration 100 – 300 mg/l

A rough idea of the difference in size between different types of particles.

Flow-based proprietary systems often only have a few seconds or minutes in which to capture sediments – hence capture of small sediments is a real challenge.

Impact of Particle Size on Performance Red line shows size distribution of Sil-Co-Sil 106, similar to the “NJ Mix” recommended for lab studies. Magenta and Blue lines represent two commercial mixes with few fines. If you expect to encounter fine particles at the location where your BMP is to be installed, you want to see test data that uses fine particles like the Sil-Co-Sil mix.

Impact of Particle Size on Performance In comparative testing of a proprietary device, under all flows tested (concentrations equal), lower removal efficiency occurred at all flow levels for the finer NJDEP mix (similar to Sil-Co-Sil) than for OK-110, which is mostly sand.

Are Results Accurate, Repeatable? Quality Control tests, data Standardized methods Methods, including quality control tests (e.g. duplicates, lab blanks, etc.) should be standard and documented well enough so that a different testing agency would be able to replicate the test and obtain similar results.

Innovative BMPs - Advanced Sedimentation Scour testing is important. A BMP should have some features in place that prevents sediment that has accumulated in the unit from being washed when subsequent high flows come through the unit. Rinker Inc, 2002

Example of scour occurring in a unit at different flows Example of scour occurring in a unit at different flows. In this test, some scour occurred as flows were being increased, even in some cases when system capacity flows were not reached.

Summary – what to look for 15 storm events 15 inches rain. 50% annual average. Particle size: mean < 100 microns - distribution: 55% sand, 40% silt, 5% clay Influent concentration: 100 – 300 mg/l Flows: range, up to 125% design capacity. Scour tests

Screen shots of the MASTEP web site. Massachusetts Stormwater Technology Evaluation Project, UMass

Important to note that MASTEP – the Massachusetts Stormwater Technology Evaluation Project – Is not the same as STEP – the STrategic Envirotechnology Partnership. STEP has been “sunsetted”: 4 technologies that had received STEP “approval” and a TSS removal rating have had these approvals pulled. They are now subject to same evaluation process as all other BMPs.

BMP Performance Comparison Table MASTEP database, main search page. Massachusetts Stormwater Technology Evaluation Project, UMass

Front page of an individual technology found on the MASTEP site. Massachusetts Stormwater Technology Evaluation Project, UMass

General information page for an individual BMP. Massachusetts Stormwater Technology Evaluation Project, UMass

Cost page.

Design Consideration page contains information on installation and maintenance requirements, sizing considerations, etc. Massachusetts Stormwater Technology Evaluation Project, UMass

Site and Environmental Consideration page contains information on any required setbacks or depth to water table, disposal of BMP-captured materials, etc. Massachusetts Stormwater Technology Evaluation Project, UMass

Performance page is most important part of a profile Performance page is most important part of a profile. It contains information about pollutant removal claims, removal efficiencies found in tests, and MASTEP evaluation of studies that have been performed on the BMP. Massachusetts Stormwater Technology Evaluation Project, UMass

MASTEP provides a summary of each test or performance study for each BMP. Massachusetts Stormwater Technology Evaluation Project, UMass

MASTEP Rating System Category 0: MASTEP has not yet reviewed performance data for this technology. Category 1: TARP-compliant field study or equivalent lab study data available for this product Cat. 2: Sound field or lab study data available – some caveats Cat. 3: Data of moderate scientific validity exists – significant caveats Cat. 4: Reliable performance lacking

Higher rating does NOT mean better performance MASTEP evaluates quality of performance DATA NOT BMP Performance Results

BMP Performance Comparison Table Performance Comparison Table at top of BMP search page is useful – opens to a spread sheet showing side-by-side comparison of removal efficiency for different pollutants, different BMPs, organized by BMP type. Only BMPs with a 1 or 2 MASTEP rating (i.e. credible studies have been performed on these BMPs) are listed in this table. Massachusetts Stormwater Technology Evaluation Project, UMass

Massachusetts Stormwater Technology Evaluation Project, UMass

MASTEP provides a summary page for most BMPs (those with ratings of 1, 2, or 3), explaining which studies were used in the MASTEP evaluation, what rating achieved, why it achieved the rating, along with additional explanatory notes. Massachusetts Stormwater Technology Evaluation Project, UMass

Lab vs. Field Tests Lab Relatively inexpensive Standardized – best for comparing 2 BMPs “Ideal” conditions, not real world – simplified Short term Field Real world. Problems are encountered Can’t control conditions Expensive Long Duration There are pros and cons associated with lab and field tests. Lab tests generally best at comparing 2 different BMPs tested under similar conditions. Field tests best at demonstrating how a system will perform in real-world field conditions.

Massachusetts Stormwater Technology Evaluation Project, UMass

Massachusetts Stormwater Technology Evaluation Project, UMass

Contact Massachusetts Stormwater Technology Evaluation Project Jerry Schoen MASTEP Project Manager Blaisdell House UMass Amherst MA 01003 413-545-5532 jschoen@cns.umass.edu Massachusetts Stormwater Technology Evaluation Project www.mastep.net

“The effectiveness of Proprietary BMPs varies with the size of the unit, flow requirements, and specific site conditions. The UMass Stormwater Technologies Clearinghouse database evaluates the quality of proprietary BMP effectiveness studies. MassDEP urges Conservation Commissions to use this database when verifying the effectiveness of Proprietary BMPs: www.mastep.net” Excerpt from MA Stormwater Handbook Volume 2 Chapter 4

Two Ways to Approve or Deny the Use of Proprietary Stormwater BMPs 1. MassDEP has reviewed the performance of a technology as determined by TARP or STEP and assigned a TSS removal efficiency. If the conditions under which it is proposed to be used are similar to those in the performance testing, presume that the proprietary BMP achieves the assigned TSS removal rate. Look at sizing, flow and site conditions. 2. Issuing Authority makes a case-by-case assessment of a specific proposed use of a proprietary technology at a particular site and assigns a TSS removal efficiency. Proponent must submit reports or studies showing effectiveness of BMP. MassDEP strongly recommends using UMass Stormwater Technologies Clearinghouse database to ensure that reports and studies are of high quality (www.mastep.net). For ultra-urban and constrained sites, proprietary BMPs may be the best choice.