San Diego Creek Watershed - Reports & Studies
	DEBRIS CHARACTERIZATION STUDY Agreement No. 8-023-258-0 July 2000

This project has been funded wholly or in part by the United States Environmental Protection Agency Assistance Agreement. The contents of this document do not necessarily reflect the views and policies of the Environmental Protection Agency or the State Water Resources Control Board, nor does mention of trade names or commercial products constitute endorsement or recommendation for use.

This report presents the results of the debris characterization study completed by the County of Orange as a part of the San Diego Creek 319 (h) grant project (Agreement No. 8-023-258-0).

The San Diego Creek 319(h) grant project, which focuses on the control of watershed and land management activities that impair beneficial-uses, is funded by the Federal Clean Water Act Section 319(h) Non-point Source Implementation Program and administered by the State Water Resources Control Board. The San Diego Creek 319(h) grant project, in addition to providing for measures to be implemented to limit pollutant effects to San Diego Creek and Upper Newport Bay, is also a component of a larger watershed effort designed to assess water quality within San Diego Creek, its tributaries, and within Newport Bay. One of the objectives of these studies is to determine the causes of receiving water beneficial-use impairments.

Debris containment systems installed in various flood control channel Locations are designed to reduce the amount of trash and debris transported into the receiving waters of Orange County. During storm events, rain runoff washes trash and debris from the streets, parking lots and open land areas into stormdrains and eventually into flood control channels and into receiving waters such as a bay or harbor. A debris containment system can be used to capture the trash and debris from the runoff before the creek or channel flows into the bay.

The debris containment systems installed within the flood control channels in the San Diego Creek watershed consist of an 18" wide net suspended below a floating boom that extends the span of the flood control channel. Figure 1 shows the debris containment system in the Santa Ana-Delhi Channel. Although this type of debris containment system captures a considerable amount of trash and debris, its' efficiency is limited by the fact that it can only remove floating materials within a vertical span of 18". In addition, heavier trash and debris can pass underneath the net and the turbulence within the channel can cause the trash and debris to be pushed under or over the net. While the removal of trash and debris can be improved by utilizing Other costlier methods, it is more desirable to reduce the amount of trash and debris by implementing source control measures.

To implement a source control measure for trash and debris, it is necessary to determine its source by characterizing the material collected by the containment systems. The 319(h) grant required that the quantity, type and source of the debris removed from the containment systems be specifically characterized from a selected storm using appropriate sampling techniques and the results compared with similar data obtained from the existing debris boom located on the Santa Ana-Delhi channel. Initially, data for this debris study was to be collected from the Santa Ana-Delhi Channel and then, with the installation of the new debris containment systems in the El Modena-Irvine and Peters Canyon channels, additional data would be collected from these two new Locations and compared to the data collected within the Santa Ana-Delhi Channel.

Although an attempt was made to collect trash and debris from the two newly installed containment systems, due to the infrequency of storms in the recent storm season and upstream construction activities in the Peters Canyon channel, no data could be obtained from these channels. All data obtained for this study was therefore from the Santa Ana-Delhi Channel debris containment system.

Even though data was not collected from Peters Canyon and El Modena-Irvine channels, the results of the debris characterization from the Santa Ana Delhi channel during the 1998-1999 and 1999-2000 storm seasons provide valuable information to move forward with implementing source control measures to reduce the pollutant effects from trash and debris. Additional data obtained from the El Modena-Irvine and Peters Canyon channels during the 2000-2001 storm season will be used to further refine the source control measures that are implemented within the watershed. Furthermore, it is anticipated that as new information is gathered over the years regarding the types and quantities of trash and debris that are removed from the containment systems the source control measures may also change to reflect this.

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This debris characterization study examines the collection, segregation and quantification of trash and debris from a debris containment system located on the Santa Ana Delhi channel after several rain events during 1998-1999 and 1999-2000.

The results of this debris characterization study will begin to provide the information necessary for implementing effective source control measures. The results provide the data needed for completing Other related 319 (h) grant tasks such as the prioritization of applicable source control measures for trash and debris and the implementation of source control measures.

Characteristics of these watersheds are described below. Figure 2 illustrates the locations of the containment systems within the San Diego Creek watershed.

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The debris containment system in the Santa Ana-Delhi Channel is located within the city of Newport Beach, just south of the Mesa Drive bridge, near Irvine Avenue and upstream of the channel's confluence with Upper Newport Bay. The Santa Ana-Delhi Channel, which is one of the major tributaries to the Upper Newport Bay, contains about 17 square miles of watershed area. This watershed is 95 % developed with land uses that include commercial, industrial, recreational and residential. Roads and residential make up a large portion of the land uses.

The debris containment system in the Santa Ana-Delhi Channel is located within the city of Newport Beach, just south of the Mesa Drive bridge, near Irvine Avenue and upstream of the channel's confluence with Upper Newport Bay. The Santa Ana-Delhi Channel, which is one of the major tributaries to the Upper Newport Bay, contains about 17 square miles of watershed area. This watershed is 95 % developed with land uses that include commercial, industrial, recreational and residential. Roads and residential make up a large portion of the land uses.

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The debris containment system located in the Peters Canyon Channel, also located in the city of Irvine, is just upstream of the El Modena-Irvine Channel confluence. This debris containment system was installed as part of Task 2.2 of the San Diego Creek 319 (h) grant. Peters Canyon Channel drains an area of about 44.7 square miles; this watershed is comprised of about 50 % agricultural use and 50 % urban areas. It is estimated that over half of the remaining agricultural area in the watershed is tributary to Peters Canyon Channel.

The components of the debris characterization study include the collection, segregation and obtaining subset samples of trash and debris from the debris containment system. A brief description of these tasks is as follows.

After each rain event, the County of Orange Public Facilities and Resources Department (PFRD), Operations and Maintenance Division deployed a work crew to the debris containment system Location to collect the trash and debris manually and deposit it into large Plastic bags. The bags were then transported to a staging area for storage and additional processing. At the staging area, the bottoms of the bags were punctured to allow water to drain and after 24 hours, the collected materials were segregated.

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The segregation step involves the separation of the trash and debris into seven defined categories based on previous trash and debris studies . These categories are: Organic, Plastic, Glass, Rubber, Metal, Paper and Cloth. Items that do not fit into these seven categories are put in the "Other" category. Items in the "Other" category are items that are large, unusual or are made of materials in several categories. Figure 3 is the field data sheet used during this process. After the trash and debris were segregated they were bagged separately by category and then weighed. The sums of all the categorized bag's weights were added to determine the Total weight of trash and debris removed from the debris containment system. For selected category samples, subset samples were obtained in order to determine Other characteristics of the collected trash and debris.

Since the collected trash and debris items were wet and some items have a significant amount of sediment attached to the surface, water content and sediment weight subset samples were collected from selected category samples.

Water content subset samples, collected from selected categorized samples, were used to estimate the amount of water absorbed within the trash and debris items. A small subset sample was obtained from each category and placed in a small aluminum tray. The trays of subset samples were weighed to obtain the wet weights. The subset samples in the trays were then dried in an oven at 60 degrees Celsius to remove water and moisture. After drying for 24 hours, the subset samples in the trays were re-weighed to determine the dry weights. The difference in the wet and dry weights of a specific category is the amount of water associated with that category.

Sediment weight subset samples, used for the estimation of sediment attached to Organic and Plastic trash and debris items, were obtained from the segregated Plastic and Organic categories only. These categories were selected based on previous study findings that these two categories make up the majority of the trash and debris collected and therefore most affected by the amount of attached sediment.

For the sediment subset sampling, one subset sample bag of Organic and one subset sample bag of Plastic were selected and weighed. The contents of these subset sample bags were then separately placed into large crates that have quarter inch diameter holes at the bottom. The crates serve as strainers to allow the sediment to be washed from the pieces of Organic and Plastic items. In some instances, scrubbing and flushing is necessary to remove the sediment. After the washing and straining, the items were shaken vigorously in the crate to remove excess wash water. The items were then placed into two separate clean bags and small holes were punctured in the bottom of the bags to allow excess water to drain. After draining, the subset samples were re-weighed. The difference in the weights before and after washing the subset samples is the weight of the sediment attached to the Plastic and Organic materials.

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Trash and debris data were collected after six storms during the 1998-1999 storm season, and one storm during the 1999-2000 storm season from the Santa Ana-Delhi containment system.

Data collected from each storm was obtained by processing the entire sample collected with exception of the February 21, 2000 storm. While the Average number of trash and debris bags collected from Other storms was 40 to 60 bags, the February 21, 2000 storm which had the highest Rainfall, produced 184 bags. With this large amount of trash and debris it was not feasible to process the entire sample. Therefore, only 15 of the 184 bags were selected at random, segregated and then weighed. The resulting data presented in the tables has been extrapolated to reflect the 184 bags collected.
During the segregation process, many of the items were found to be common. Table 1 is a list of the common items found. After the samples were segregated and drained of excess water, the wet weights of each category were measured and recorded. The wet weight data along with the Total Rainfall for each storm is presented inTable 2.

For the estimation of the amount of water absorbed within the trash and debris items, the water content within each subset was determined. These results are presented in Table 3 and Table 4. In evaluating the water content percent Averages, it was observed that some numbers did not appear to be consistent with the overall data set. The Dixon test was used to determine if the suspected points were outliers to a normal distribution. The outlying data was excluded prior to calculating the Averages by using the following procedure:

The data set was ordered from smallest to largest that is X1 < X2 < X3 < … Xn. The Dixon ratio r, which is a function of n was calculated.

Number of Points	Ratio Calculated
n = 3 to 7	r10
n = 8 to 10	r11
n = 11 to 13	r21
n = 14 to 25	r22

Depending on which point was suspected of being the outlier, the ratio was calculated in the following manner:

r	If Xn is Suspect	If X1 is Suspect
r10	(Xn-Xn-1)/(Xn-X1)	(X2-X1)/(Xn-X1)
r11	(Xn-Xn-1)/(Xn-X2)	(X2-X1)/(Xn-1-X1)
r21	(Xn-Xn-2)/(Xn-X2)	(X3-X1)/(Xn-1-X1)
r22	(Xn-Xn-2)/Xn-X3)	(X3-X1)/Xn-2-X1)

Using Table A.7 for calculated confidence values, the calculated ratio was compared to the critical value at a confidence level of 95%. If the calculated value was greater than the tabled value the suspected point was rejected and the distribution was re-tested to confirm normality.

For normal distributions the mean is calculated as the arithmetic mean, that is:

the confidence limits for the mean of a normal distribution with unknown variance is given by

where s is the standard deviation of the data set andis from table A2 . Using a = 0.05 the upper and lower limits are calculated. The true mean m will occur outside of this range 5% of the time.

After excluding outlying data, the Averages are calculated. The resulting calculated Averages showed that Organic and Paper categories had the highest water content Averages of 65% and 40%, respectively.

The sediment subset data and the estimation of the percent sediment associated with Organic and Plastic categories are presented in Table 5. The Average percent composition of sediment attached to the Organic and Plastic items in the trash and debris samples was also calculated after excluding anomalous data with the Dixon test. The resulting calculated Average indicates Organic materials Averaged 34% weight sediment and Plastic materials contained 31% weight sediment.

The estimation of the water content and sediment weight Averages were then used to estimate the adjusted or actual weight of trash and debris. To arrive at the estimated adjusted values, the wet weight values are reduced by the Average water content percent for each category and also reduced by the Average sediment weight percent for Organic and Plastic categories. The adjusted trash and debris weights correlated with the amount of Rainfall for each storm presented in Table 6.

Figure 4 illustrates this correlation in a graph, which demonstrates that (except for the March 25, 1999 storm), the amount of trash and debris collected is generally proportional to the amount of Rainfall.

The adjusted weight values were used to estimate the percent composition of the trash and debris. The resulting adjusted composition of the trash and debris is presented in Table 7 and Figure 5 is a graph of these values.

As a result of the calculations, the Average adjusted composition percent of Organic and Plastic categories at Santa Ana Delhi channel were approximately 47% and 34%, respectively. The sum of Averages for the remaining categories is less than 20%.

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The data collected from all the storms provided consistent and useful trash and debris characterization information. The results of this study indicate that the percent composition of the trash and debris followed a similar pattern for each of the storms. In general, the Organic (47%) and Plastic (34%) were found to be the predominant materials collected from the debris containment system. This information is important for implementing a source control program to reduce the amount of trash and debris from impacting the Upper Newport Bay and also provides the baseline for measuring future trash and debris reductions.

These results support data obtained from the 15th Annual California Coastal Commission's Cleanup Day that Plastic items constitute a significant portion of trash and debris. During the event in September 1998, the top five items picked up were cigarette butts, foamed Plastic pieces, Plastic pieces, Paper pieces, and Plastic food bags/wrappers.

This addendum includes additional data obtained from the El Modena-Irvine Channel after the completion of the original Santa Ana-Delhi debris characterization study. Due to the infrequency of storms during the September - December 2000 period, only one storm sample could be collected from the El Modena-Irvine channel debris containment system. Trash and debris could not be collected from Peters Canyon Channel because of few storms and an upstream portion of the channel supports vegetation which prevents trash and debris from flowing downstream to the debris containment system.

The results of the characterization of the trash and debris collected from the El Modena-Irvine channel for the storm occurring on October 27, 2000 are presented in the revised Table 2. The recent data was adjusted using the same correction factors for water content and sediment as previously obtained from the Santa Ana-Delhi data and are presented in the revised Table 7.

The majority of trash and debris from the El Modena-Irvine channel were characterized to be 18% Organic and 48% Plastic and 16% Rubber. The composition of remaining categories (Glass, Metal, Paper and Cloth) Total less than 20%. The high percentage composition of Rubber was attributed to the large number of balls (tennis, soccer, basketball, etc.) A graph of the summary data for both Santa Ana-Delhi and El Modena-Irvine channels are presented in the revised Figure 5.

In comparing the data from the two containment systems, it is apparent that the composition of trash and debris are different. The amount of Organic materials found at El Modena-Irvine (18%) was significantly less than the Average (47%) at Santa Ana-Delhi. The amount of Plastic materials found at El Modena-Irvine (48%) was significantly higher than the Average (34%) at Santa Ana-Delhi. In addition, the composition of Rubber materials for El Modena-Irvine (16%) is much higher than the Average for Santa Ana-Delhi (4.9%). The significance of this difference, however, is difficult to evaluate since the data for El Modena-Irvine was only for one storm event. Therefore, it is recommended that future grant funds be obtained to collect additional data from the El Modena-Irvine and Peters Canyon channels to assist in the evaluation of this and future data.

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TABLES

Table 1 - click here for referring text
Common Trash Debris
Category	Item
Organic	Leaves, twigs, branches, grass clippings, flowers, fruit, seeds, pine cones, pods, lumber materials, pencils, chair legs, bark
Plastic	Plastic: bags, pens, wrappers, caps, straws, balls, sports bottles, Plastic water and beverage bottles, unidentified Plastic ends, six pack beverage container holders, fruit juice containers, toys, oil containers, misc. hard Plastic items, chords, tubes a
	Foamed Plastics: plates, cups and lids, peanuts for packaging, surfboard foam, foam Plastic sheets for grocery store packaged meats, foam packaging materials
Glass	Beverage bottles, light bulbs, misc. Glass pieces,
Rubber	Tennis balls, racket balls, balloons, gloves, inner tubes, Rubber shoes and sandals, misc. Rubber pieces, condoms, sun Glass holder, Rubber tubes
Metal	Aerosol containers, aluminum beverage cans, foil gum wrappers, tin cans
Paper	NewsPaper, cardboard, cigarette butts, fast food cups, white Paper
Cloth	Fabrics, Clothing remnants, cotton/nylon strings

Table 2 - click here for referring text
SANTA ANA-DELHI CHANNEL TRASH & DEBRIS WET WEIGHT PERCENT COMPOSITION
	STORM DATE
	2/9/99	3/11/99	3/15/99	3/25/99	4/7/99	4/12/99	2/21/00*	Average
Rainfall	0.16	0.12	0.20	0.56	0.16	0.08	0.82
Organic	67.9%	60.3%	77.2%	77.8%	74.7%	76.5%	59.8%	70.6%
Plastic	22.8%	32.0%	18.0%	15.9%	14.2%	18.6%	30.6%	21.7%
Glass	0.9%	0.0%	1.2%	0.8%	0.7%	0.4%	3.9%	1.1%
Rubber	1.1%	1.1%	1.0%	1.6%	1.3%	1.2%	2.8%	1.4%
Metal	1.2%	5.7%	1.2%	2.8%	0.9%	2.3%	2.0%	2.3%
Paper	1.2%	0.9%	0.8%	0.7%	0.4%	0.9%	0.4%	0.8%
Cloth	0.2%	0.0%	0.7%	0.4%	0.2%	0.0%	0.4%	0.3%
Other	4.9%	0.0%	0.0%	0.0%	7.5%	0.0%	0.0%	1.8%
* data extrapolated from 15 bags sampled of 184 Total