Management of Non-Point Source Pollution CE 296B

Management of Non-Point Source PollutionCE 296B Department of Civil Engineering California State University, Sacramento Lecture #12, March 17, 1998 Monitoring - Part I

I. With respect to the management of non-point source pollution, what does the term Monitoring, entail? This is not just an academic question. The management of non-point source pollution differs substantially from the management of point source pollution such as municipal wastewater. With municipal wastewater, it is possible to assess performance and compliance by sampling and testing effluent. A mindset surrounding non-point source pollution management is that performance and compliance can be assessed primarily by sampling and testing effluent.

I. With respect to the management of non-point source pollution, what does the term Monitoring, entail? (cont.) A. What are the characteristics of point vs. non-point source pollution that influence how we will define monitoring? 1. Point source pollution: • Management efforts take place primarily in one location. • Management efforts are primarily technological in nature and allow for process control. • As the discharge is relatively steady, constant in composition and takes place in one point, the impact on receiving waters is relatively easy to assess.

POTW Schematic of Point Source Pollution • At single outfall: • steady flow • constant conc. Receiving Water

I. With respect to the management of non-point source pollution, what does the term Monitoring, entail? (cont.) • A. What are the characteristics of point vs. non-point source pollution that influence how we will define monitoring? (cont.) 2. Non-point source pollution: • Management efforts take place in countless locations spread throughout a large area. • Management efforts are diverse in type. • As the discharge is highly variable and takes place in many locations, the impact on receiving waters is difficult to assess.

Receiving Water Schematic of Non-Point Source Pollution Urban Flow Suburban flow: Irrigation Storm Flow

I. With respect to the management of non-point source pollution, what does the term Monitoring, entail? (cont.) B. As a point of comparison, how is monitoring accomplished for point source pollution? Three primary areas of work: 1. Monitoring of process control 2. Monitoring of effluent quality 3. Monitoring of downstream impacts of discharge In each case, the central technique is sample collection and analysis.

Monitoring of Process Control at a POTW • Consider a flow diagram of a typical POTW: • Sample and analyze influent characteristics to: • Obtain ongoing characterization profile of influent, BOD strength, solids content, flow rate. • Identify specific constituents that source control programs could help control. • Sample and analyze influent and effluent from unit processes to obtain performance data. Use data to optimize performance of a technological system.

Monitoring of Effluent Characteristics at a POTW • Requirements in the Porter-Cologne Act and Clean Water Act require point source dischargers, the real kind, to monitor effluent quality as part of any NPDES permit. There are multiple purposes to this and include: • Identifying the presence and amount of particularly troublesome constituents. (e.g., Hg, Pb, synthetic organics) • Meeting concentration based numerical effluent limits • Assessing the load, typical units - mass per day, of conventional and exotic constituents released to the receiving water.

Monitoring of Downstream Impacts of POTW Discharge Because of the well defined nature of point source discharge, both in terms of steady flow and consistent constituent concentrations, it is relatively ease to determine the impact of that discharge downstream. • By sampling downstream effluent, one can assess the amount of dissolved oxygen depletion due the the noted BOD concentration in POTW effluent as a good example. • Because of the well defined characteristics of POTW effluent, one can easily assess the magnitude of the loading of many different constituents associated with the facility.

I. With respect to the management of non-point source pollution, what does the term Monitoring, entail? (cont.) C. What are some of the objectives of a monitoring program an effort to manage non-point source pollution? 1. For a specific BMP, one would certainly like to establish effectiveness of that BMP in managing pollutants. Because the very nature of non-point source pollution, such an evaluation would have to be done for a large number of circumstances. Low-flow, high-flow. Seasonal differences.

I. With respect to the management of non-point source pollution, what does the term Monitoring, entail? (cont.) • C. What are some of the objectives of a monitoring program an effort to manage non-point source pollution? (cont.) 1. BMP effectiveness testing - more: Additionally, in assessing BMP effectiveness, there is also the difference between source control type measures and treatment type measures. While it is possible, although not easy, to measure the pollutant removal from a detention basin, how do you determine if stenciling drain inlets has reduced pollution?

I. With respect to the management of non-point source pollution, what does the term Monitoring, entail? (cont.) • C. What are some of the objectives of a monitoring program an effort to manage non-point source pollution? (cont.) 2. An effort to manage non-point source pollution might involve the implementation of over 100 different BMPs, some of which are implemented in thousands of locations. One would certainly like to know how complete the effort has been or is to implement those BMPs.

I. With respect to the management of non-point source pollution, what does the term Monitoring, entail? (cont.) • C. What are some of the objectives of a monitoring program an effort to manage non-point source pollution? (cont.) 3. One would like to know how much non-point source effluent there is and what is in it. Major problem, there may be countless points of discharge and many different conditions under which that discharge takes place.

I. With respect to the management of non-point source pollution, what does the term Monitoring, entail? (cont.) • C. What are some of the objectives of a monitoring program an effort to manage non-point source pollution? (cont.) 4. One would like to know what the effect on receiving waters is of non-point source discharges in the sense of chemical characteristics. 5. One would like to know how the realization of beneficial uses is affected by non-point source discharges.

I. With respect to the management of non-point source pollution, what does the term Monitoring, entail? (cont.) • C. What are some of the objectives of a monitoring program an effort to manage non-point source pollution? (cont.) In summary, it is desirable to monitor to meet the following objectives: • BMP effectiveness • BMP implementation • Effluent quality • Affect on water quality objectives • Affect on beneficial uses All the while, the cost of the management program needs to be assessed

Discussion Break Say you are designing a monitoring element of a non-point source management plan. You have a modest amount of money to do this and need to spend your money wisely. On what would you spend money first? Assume that the regulators will give you freedom to chose. • BMP effectiveness • BMP implementation • Effluent quality • Affect on water quality objectives • Affect on beneficial uses

Q Time II. With respect to sample collection and analysis type monitoringof water, what is involved at a nuts and bolts level? A. First distinction is the difference between a grab and composite sample. Consider the classic hydrograph: A grab sample take place at a point in time. The goal of a composite sample is to collect a sample containing the average concentration experienced over a period of time.

II. With respect to sample collection and analysis type monitoringof water, what is involved at a nuts and bolts level? (cont.) B. How are grab samples collected? Physically, this could be complicated, but conceptually it is simple. A portion of the flow at the moment in time one is interested in, is placed in an appropriate sample container. C. How are composite samples collected? Two primary different possibilities exist: 1. Flow splitting 2. Flow proportioned samples

Q Time Collection of Composite Samples - Basics Area = Q (vol./unit time) x Time = Volume • Note that on a hydrograph, the area under the curve represents total flow volume of the time period in question. • The true average concentration for the specified time period would be the total mass (load) divided by the total volume (area). • With an accurate estimation of the average concentration, coupled with total flow measurement yields the mass loading.

Q Time Composite Samples - Flow Splitting Method Area to be sampled: • Recall the classic hydrograph: • If an equal fraction of the flow, as an example 1/100th Q, is diverted into a sample container throughout the sample time, one has a composite sample. This works best when the flow and concentrations are relatively constant. Then, it works great!!

A3 A2 A4 A1 A5 Q A6 A7 A8 t2 to t6 t7 t4 t8 t1 t5 t3 Time Composite Samples - Flow Proportioned Method - I If A1=A2=A3=…=A8, Then, V1=V2=V3=…=V8 • Recall the classic hydrograph, made much bigger:

Composite Samples - Flow Proportioned Method - II • If equal sized samples are taken at t1, t2, t3, …,t8 and mixed together, then a good approximation of the average concentration under the hydrograph has been collected. • For such a system to work, the following information must be accurate: • The estimate of storm size, or dry weather flow • The estimate of total run-off from the storm size • The measurement of flow • If the above items are true, fancy equipment exists to help in the process.

Fringe Benefit of Flow-Proportioned Sample - Pollutograph • If individual samples taken at t1, t2, t3,…t8 are analyzed separately, a picture of the constituent concentrations with time can be established. • Currently, this is called a pollutograph, and on the rare occasions they have been collected, they have served to study the phenomena of first flush. • Another possible use is to correlate constituent concentrations with flow rate. • It would be nice if more of these existed.

II. With respect to sample collection and analysis type monitoringof water, what is involved at a nuts and bolts level? (cont.) D. What are well collected composite samples from storm events called? Event Mean Concentration (EMC) Samples E. If one is dealing with storm water run-off, the size of the catchment can influence the results. Consider hydrographs from a large and small catchment. Small Catchment, < 100 acres Large Catchment, > 20 sq. mi.

Discussion Break Based on what you have just seen, what kind of caveats would you put on EMC concentrations taken at: Large catchments? Small catchments?

II. With respect to sample collection and analysis type monitoringof water, what is involved at a nuts and bolts level? (cont.) F. When sampling for constituents, which ones are appropriate for grab samples and which ones for composite samples? 1. Grab: Anything that is perishable • Samples associated with indicator organism analysis or pathogen identification • Volatile organic compounds • NOT BOD. Icing will preserve these samples 2. Composite: Anything else

Discussion Break Why do you think there is a basic preference for composite samples? Could this ignore the impact of concentration effects at moments in time during an event?

II. With respect to sample collection and analysis type monitoringof water, what is involved at a nuts and bolts level? (cont.) G. What are some of the major pitfalls in actually collecting samples for non-point source pollution? Several categories, among them: 1. The extreme difficulty of collecting sheet flow samples. Problem is though, one might be real interested in collecting sheet flow samples. Examples include: • Erosion at different points on the slope. • Flow from streets before the piping system is encountered.

Sample collection tube and device • II. With respect to sample collection and analysis type monitoringof water, what is involved at a nuts and bolts level? (cont.) • G. What are some of the major pitfalls in actually collecting samples for non-point source pollution? Several categories, among them: 2. If one is collecting from a conveyance system (pipe, channel, etc.), it’s usually from a point in the flow cross-section, question is, is it representative of the cross-section? Turbulent Flow Helps

Sampler and sample line • II. With respect to sample collection and analysis type monitoringof water, what is involved at a nuts and bolts level? (cont.) • G. What are some of the major pitfalls in actually collecting samples for non-point source pollution? Several categories, among them: 3. Avoidance of backwater effects, this can be a particular problem with treatment type BMP’s

II. With respect to sample collection and analysis type monitoringof water, what is involved at a nuts and bolts level? (cont.) • G. What are some of the major pitfalls in actually collecting samples for non-point source pollution? Several categories, among them: 4. When the non-point source pollution is storm water in the western U.S. capturing a representative storm can be problematical. Regulations can dictate how representative a storm is based on among others: • Storm size • Storm intensity • Storm duration • Antecedent dry period

II. With respect to sample collection and analysis type monitoringof water, what is involved at a nuts and bolts level? (cont.) • G. What are some of the major pitfalls in actually collecting samples for non-point source pollution? Several categories, among them: 5. When the non-point source pollution is storm water the logistics of the sample collection and analysis are substantial: • Deciding if the storm is going to be a good one • Getting people to the site • Getting perishable samples to the lab • Making sure the lab people are there • and on, and on , and on!!!!

Management of Non-Point Source Pollution CE 296B