Presentation on theme: "The University of Massachusetts Water Resources Research Center works with MassDEP under a contract funded by the Federal 319 grant program to evaluate."— Presentation transcript:
1Massachusetts Stormwater Technology Evaluation Program Evaluating Stormwater BMPs Spring 2013
2The 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 siteMassachusetts Stormwater Technology Evaluation Project, UMass
3Stormwater treatment has two primary objectives: address water quality – i.e. reduce flood flows
4And 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.
5Sediment 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.
6Particle 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.
7Many BMPs are designed to slow moving water down, to give sediments time to settle out.
8Filtering is another common way to treat sediments: some BMPs use vegetation or other media to filter or trap water and pollutants it contains.
9Constructed Wetlands Removal Efficiency: 65-80% average 80% MassDEP TSSRemoval CreditKey Features:Large areaPeak flow controlBiological treatmentMaintenance: low to moderateCost: marginally higher than wet pondsAdvantages:Relatively low maintenance costsHigh pollutant removal efficiencyEnhance aestheticsDisadvantages:Large land requirementsUntil vegetation is established, lower pollutant removal efficienciesHigh construction costs2002Source: MassDEP, Massachusetts Stormwater Handbook
10Extended Detention Basins TSS Removal Efficiency:60-80% average50% MassDEP TSSRemoval CreditKey Features:Large areaPeak flow controlMaintenance: lowCost: low tomoderateAdvantages:Least costly BMP that controls both quantity and qualityGood retrofitting option for existing basinsRemoves TSS and sorbed pollutantsBeneficial habitatLess hazards than permanent poolsDisadvantages:Infiltration is negligibleRemoval of soluble pollutants minimalModerate to high maintenance requirementsPotential contributor to downstream warmingPotential sediment resuspension after large stormsSource: MassDEP, Massachusetts Stormwater Handbook
11Water Quality Swales Removal Efficiency: 65-805 average 70% MassDEP TSS Removal CreditKey Features:Higher pollutant removal rates than drainage channelsTransport peak runoff and provide some infiltrationMaintenance: low to moderateCost: low to moderateAdvantages:Control peak discharges by reducing runoff velocity and promoting infiltrationProvides pretreatment by trapping sedimentsGenerally less expensive than curve and gutter systemsDisadvantages:Higher degree of maintenance than curb and gutter systemsSubject to damage from off-street parking and snow removal2002Source: MassDEP, Massachusetts Stormwater Handbook
13Innovative BMPs – Media Filtration Removal Efficiency:50-80% averageDesign rate: case by case evaluationDesign Features:small areaOil and Grease controlMaintenance: moderateCost: moderateFiltration units force water through various media to trap sediments.Stormwater Management Inc, 2002Massachusetts Stormwater Technology Evaluation Project, UMass
14Innovative BMPs - Hydrodynamic Removal Efficiency:No treatment to 35%Design rate: case by case evaluationDesign Features:small areaOil and Grease controlMaintenance: moderateCost: moderateVortechs Inc, 2002
15TARP- 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; andShare technology information with potential users in the public and private sectors using existing state supported programsCAILMAMDNJNYPAVATX
16Performance Verification - TARP Storm Event Criteria to SampleMore 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 SetAt 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
17Performance Verification - TARP Stormwater Sampling LocationsSampling locations for stormwater BMPs should be taken at inlet and outlet.Sampling MethodsProgrammable automatic flow samplers with continuous flow measurements should be usedGrab 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 MethodsPrimary and secondary flow measurement devices are required.
18Is There Enough Data? Lab Studies Field Studies 15 test runs 15+ storms15 inches of rainfallThese 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.
19Are the Data Representative? Weather conditionsTopography, land useSoils, sedimentsBy 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.
20Storms can produce highly variable flow patterns, and differences in concentrations of pollutants. Does a study capture such variability?Massachusetts Stormwater Technology Evaluation Project, UMass
24Are the Data Representative?, Weather, Flows Multiple samples per eventField Studies: must include high flow/intensity stormsConsecutive stormsSample all yearLab 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.
25Data 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.
26A 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.
27For 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.
28Are 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 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% clayInfluent concentration 100 – 300 mg/l
29A rough idea of the difference in size between different types of particles.
30Flow-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.
31Impact 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.
32Impact 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.
33Are Results Accurate, Repeatable? Quality Control tests, dataStandardized methodsMethods, 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.
34Innovative 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
35Example 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.
36Summary – what to look for 15 storm events15 inches rain. 50% annual average.Particle size: mean < 100 microns- distribution: 55% sand, 40% silt, 5% clayInfluent concentration: 100 – 300 mg/lFlows: range, up to 125% design capacity.Scour tests
37Screen shots of the MASTEP web site. Massachusetts Stormwater Technology Evaluation Project, UMass
39Important 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.
45Design Consideration page contains information on installation and maintenance requirements, sizing considerations, etc.Massachusetts Stormwater Technology Evaluation Project, UMass
46Site 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
47Performance 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
48MASTEP provides a summary of each test or performance study for each BMP. Massachusetts Stormwater Technology Evaluation Project, UMass
49MASTEP Rating SystemCategory 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
50Higher rating does NOT mean better performance MASTEP evaluatesquality of performance DATANOTBMP Performance Results
51BMP 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
53MASTEP 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
54Lab vs. Field Tests Lab Relatively inexpensive Standardized – best for comparing 2 BMPs“Ideal” conditions, not real world – simplifiedShort termFieldReal world. Problems are encounteredCan’t control conditionsExpensiveLong DurationThere 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.
57Contact Massachusetts Stormwater Technology Evaluation Project Jerry SchoenMASTEP Project ManagerBlaisdell HouseUMassAmherst MA 01003MassachusettsStormwater TechnologyEvaluation Project
58“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:Excerpt from MA Stormwater HandbookVolume 2 Chapter 4
59Two 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.