Metabolic Studio’s Pilot Wetland Study Treatment

Metabolic Studio

1745 N Spring St. #4

Los Angeles, CA 90012

(323) 226-1158

Metabolic Studio’s Pilot Wetland Study

Treatment Performance Report (DRAFT) - A Part of the Bending the River Back Into the City

D R A F T - For Discussion Purposes Only

Metabolic Studio Pilot Wetland Study

Page Intentionally Left Blank


i Metabolic Studio Pilot Wetland Study

TABLE OF CONTENTS

Page

1. INTRODUCTION ................................................................................................. 1

1.1 Background ............................................................................................. 1

1.2 Water Quality Objective ...................................................................... 2

1.3 Baseline Conditions ................................................................................ 3

1.4 HSSF Wetlands and Design Constraints ............................................ 4

1.5 Study Objectives ..................................................................................... 5

2. TREATMENT PERFORMANCE .......................................................................... 7

2.1 Indicator Bacteria .................................................................................. 7

2.2 Physical and Chemical Water Quality Parameters .................... 10

3. HYDRAULIC RETENTION TIME ....................................................................... 17

4. VEGETATION COVERAGE ............................................................................ 19

5. CAPITAL AND O&M COSTS.......................................................................... 21

5.1 Capital Costs ......................................................................................... 21

5.2 O&M Costs .............................................................................................. 22

5.3 Total Annual Costs ................................................................................ 22

6. CONCLUSIONS ................................................................................................ 24

7. REFERENCES ..................................................................................................... 26


TABLE OF CONTENTS (Continued)

Page

ii Metabolic Studio Pilot Wetland Study

LIST OF TABLES

Table 1 Mean and Theoretical Hydraulic Retention Time ........................ 17

Table 2 Capital costs for one and three three-tank in-series systems ... 22

Table 3 Annual O&M costs for one and three three-tank in-series

systems ....................................................................................................... 22

Table 4 Annual operating costs for one and three three-tank in-

series systems ............................................................................................ 23

Table 5 Physical and Chemical Water Quality Parameters Measured

in the Field ................................................................................................. 29

Table 6 Physical and Chemical Water Quality Parameters Measured

in the Laboratory ..................................................................................... 30

Table 7 Water Quality Data of Captured Rainwater Stored in

Cisterns Onsite and LAR Water ........................................................... 32



Page

iii Metabolic Studio Pilot Wetland Study

LIST OF FIGURES

Figure 1 Locations of Bending the River Back into the City, the

wetland site, and grab sampling ......................................................... 2

Figure 2 Total coliform geometric mean concentration for samples

collected at selected locations ........................................................... 7

Figure 3 Fecal coliform geometric mean concentration for samples


Figure 4 Enterococci geometric mean concentration for samples


Figure 5 Average total suspended solids at selected locations along

the treatment systems ........................................................................... 11

Figure 6 Average turbidity at selected locations along the

treatment systems ................................................................................... 12

Figure 7 Average conductivity at selected locations along the three

treatment systems ................................................................................... 13

Figure 8 Average oxidation reduction potential (ORP) at selected

locations along the three wetland systems .................................... 14

Figure 9 Average BOD5 at selected locations along the treatment

systems ....................................................................................................... 15

Figure 10 Average nitrate concentration at selected locations along

the three wetland systems ................................................................... 16

Figure 11 RWT effluent concentration for the gravel and clay pellet

wetlands .................................................................................................... 18

Figure 12 Vegetation coverage of individual wetland cells in the three

wetland systems. ..................................................................................... 20

Figure 13 a) Water truck; b) floatable pump .................................................... 33

Figure 14 a) Influent storage 1 at the lower level and fabric filter

installation prior to refilling the storage tanks; b) influent

storage 2 and the intermediate tank ................................................ 33



Page

iv Metabolic Studio Pilot Wetland Study

Figure 15 The pilot wetland site plan ................................................................... 34

Figure 16 The layout of the wetland plants in each wetland cell. ............. 35

Figure 17 A flow control and recording setup installed at the influent

of the clay pellet wetland, C. ............................................................. 35

Figure 19 An effluent sampling port located at the end of each

wetland cell .............................................................................................. 36

LIST OF APPENDICES

Appendix 1 – Water Quality Results

Appendix 2 – Rainwater Versus LAR Water Quality

Appendix 3 – Materials and Methodology


Acronyms and Abbreviations

v Metabolic Studio Pilot Wetland Study

BOD5 Five-Day Biochemical Oxygen Demand

BRBC Bending the River Back to the City

COD Chemical Oxygen Demand

CTRS California Toxic Rule Standard

DCT Donald C. Tillman Water Reclamation

Plant

DTLA Downtown Los Angeles

E. coli Escherichia coli

HRT Hydraulic Retention Time

HSSF Horizontal Subsurface Flow

IN Influent

LACDPH Los Angeles County Department of Public

Health

LAG Water Reclamation Plants

LAR Los Angeles River

MCL Maximum Contamination Level

MPN Most Probably Number

NTU Nephelometric Turbidity Units

ORP Oxidation Reduction Potential

PAHs Polycyclic Aromatic Hydrocarbons

PCBs Polychlorinated Biphenyls

PSF Pounds Per Square Foot

RWT Rhodamine WT

TDS Total Dissolved Solids

TOC Total Organic Carbon

TSS Total Suspended Solids


1 Metabolic Studio Pilot Wetland Study

1. INTRODUCTION

1.1 Background

Water scarcity due to climate change and prolonged droughts in arid

regions has fueled a growing interest in capturing and using stormwater

and dry-weather runoff for non-potable water applications. These

innovative reuse approaches not only help diversify local water resources,

but also help municipalities achieve discharge requirements specified in

National Pollutant Discharge Elimination System (NPDES) Permits meeting

ambient water quality criteria, such as Total Maximum Daily Loads

(TMDLs).

The 48-mile long Los Angeles River (LAR) flows through the heart of

Downtown Los Angeles (DTLA) discharging into the Pacific Ocean via

Queensway Bay in Long Beach. LAR flow in the DTLA area is comprised

primarily of 1) Title 22 recycled water discharges from the Los Angeles-

Glendale (LAG) and Donald C. Tillman (DCT) Water Reclamation Plants,

2) groundwater underflow from the Glendale Narrows and Arroyo Seco

tributary (US Army Corps of Engineers, 2013), and 3) overflows from the

Japanese Garden, Lake Balboa, Bull Creek, and the Sepulveda Basin

Wildlife Area (US Army Corps of Engineers, 2012).

Dry-weather base flow in the LAR that exceeds 72 cubic-feet-per-second

(cfs) is estimated to be greater than 90% of the time in the DTLA area

(Geosyntec Consultants, 2013). Based on a ten-year average discharge

of 62 cfs, combined discharges from the LAG and DCT water reclamation

plants account for over 80% of total dry-weather flow (Geosyntec

Consultants, 2013). Such a unique flow composition makes the LAR water

in the DTLA area relatively clean.

The capture of dry-weather runoff from the LAR to provide non-potable

water for spray irrigation in nearby public parks was proposed in 2013

(Geosyntec Consultants, 2013) as part of the “Bending the River Back to

the City” (BRBC) project – an alternate water use project envisioned by

Metabolic Studio (the Studio). The project site is located two miles

northeast of DTLA between the 110, 5, and 101 freeways (Figure 1). The

proposed project will consist of an inflatable rubber dam within the LAR

channel diverting dry-weather flow to a water wheel. The water wheel lifts



the water to a treatment and storage system prior to distribution to nearby

parks for spray irrigation. Less than one percent of the diverted flow will be

lifted by the water wheel, while the remaining flow will immediately flow

back into the LAR through a subsurface flow channel.

Figure 1 Locations of Bending the River Back into the City, the wetland site, and grab

sampling

1.2 Water Quality Objective

The Los Angeles County Department of Public Health (LACDPH) sets the

water quality objectives for the use of non-potable water sources within

the County of Los Angeles, including runoff from the LAR, for aboveground

non-potable uses. At the time when BRBC was proposed, Guidelines for

Harvesting Rainwater, Stormwater, & Urban Runoff for Outdoor Non-

Potable Uses (LACDPH, 2011. “2011 Guidelines”) was the effective

guidelines. It stipulated that non-potable water for aboveground outdoor

non-potable uses shall meet the following single sample limits for indicator

bacteria at the point of use when distributed offsite:

• Total coliforms <10,000 CFU/100mL;

• Fecal coliforms <400 CFU/100mL; and

• Enterococcus <104 CFU/100mL.



It is noted that the above limits are the same as the Marine REC-1 Water

Quality Objectives for the Long Beach City Beaches and Los Angeles River

Estuary (USEPA Region IX, 2012). In February 2016, the 2011 Guidelines were

replaced by “Guidelines for Alternate Water Sources: Indoor and Outdoor

Non-Potable Uses (2016 Guidelines, (LACDPH, 2016)) to make the non-

potable water use requirements consistent with the California Plumbing

Code (LACDPH, 2016). The Tier 3 Standards in the 2016 Guidelines specify

that aboveground non-potable water uses shall meet the following water

quality objectives:

• NSF 350 Standards or Title 22 Recycled Water Quality equivalence

at the point of use;

• All bacterial limits at point of use when distributed off site;

• California Maximum Contamination Levels (MCLs); and

• The California Toxics Rule Standards (CTRS).

It is noted that the total coliform limit of 2 MPN/100mL referenced in the

2016 Guidelines is intended to benchmark performance and reliability of

disinfection. The presence of total coliform is not necessarily associated

with fecal contamination. However, with this major change, disinfection is

expected to be needed as the final treatment step prior to distribution.

1.3 Baseline Conditions

Dry-weather sampling events were performed between July 2012 and

October 2014 to determine concentrations of indicator bacteria and

other contaminants in the LAR water (Geosyntec Consultants, 2015). A

total of 144 parameters listed in the MCLs, REC 1 and 2, CTRS, and Title 22

were analyzed during the first sampling event. These parameters can be

broadly divided into: general chemistry parameters, pesticides, metals,

indicator bacteria, nutrients, organic compounds, polychlorinated

biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs).

Water quality parameters that did not meet the applicable regulatory

limits were selected as “priority parameters” and monitored during the

subsequent 21 sampling events to provide data necessary for treatment

design. These priority parameters were total coliform, fecal coliform,

Escherichia coli (E. coli), enterococcus, specific conductance, turbidity,



and pH. The results from the first sampling event concluded that LAR water

did not have exceedance concerning pesticides, metals, organic

compounds, PCBs, and PAHs.

1.4 HSSF Wetlands and Design Constraints

Horizontal subsurface flow (HSSF) wetlands have been used for a wide

range of water treatment applications including: nitrogen and phosphate

removal (Tanaka, N., Karunarathna, A.K. & Jindasa, K.B.S.N., 2008),

graywater treatment (Dallas, S. & Ho, G., 2005), highway runoff treatment

(Terzakis, S. et al, 2008), heavy metal removal from acid mine drainage

(Sheoran, A. & Sheoran, V., 2006), and stormwater runoff treatment (Idris,

S.M. et al, 2012). It has been reported that 99% or greater indicator

bacteria reduction is achievable using HSSF wetlands (Kadlec, R.H. &

Wallace, S.D., 2009).

HSSF wetlands are considered as an attractive alternative to other physio-

chemical and biological treatment options. In addition to proven water

quality treatment performance, HSSF wetlands bring added benefits of

greening highly developed urban spaces, creating wildlife habitats,

requiring little energy input, and reducing carbon dioxide (a greenhouse

gas).

The reported treatment performance and benefits above led the Studio

to consider the use of this treatment option to treat LAR water at the BRBC

facilities in early 2014. In a memo prepared by Geosyntec (2014), a

conventional full-scale rectangular HSSF wetland with two 5.5 ft. deep

gravel beds would occupy a footprint of 65,000 square foot. Such a large

footprint was deemed impractical due to the space constraint.

To save space, the Studio subsequently expressed a preference of

installing part of the wetland on top of the Studio’s main building roof. To

accommodate this siting preference, the wetland systems would be

required to meet a loading limit of no more than 150 pounds per square

feet (psf). Also, the shape of the roof selected had a five-sided polygon

(See Figure 1), this would mean that a wetland with a flexible configuration

would be desirable to optimize the use of available space. Given these

constraints, alternative media with lower density than conventional gravel

media and smaller and shallower beds would need to be considered.



Also, the Studio expressed a preference for using media from sustainable

sources.

In order to demonstrate the feasibility of using a wetland system that

would meet the above criteria, a pilot study was subsequently planned.

During the design phase, a total of 15 alternative media were considered,

including: commercial media products (e.g., Growth Rock, Rockwool,

expanded clay pellets), natural rock minerals (e.g., perlite, pumice,

gravel), and agricultural waste (e.g., wood chips, rice hull, coconut coir).

Three media types, namely gravel, coconut coir, and clay pellets, were

ultimately selected. Gravel was selected because of its frequent use as

wetland media and was recommended in preliminary design proposed

by Geosyntec (2014). Coconut coir was selected as a sustainable and low

density alternative that has been used for HSSF wetlands (Tanaka, N.,

Karunarathna, A.K. & Jindasa, K.B.S.N., 2008). Expanded clay pellets were

selected as an alternative because its density was between gravel and

coconut coir, and they are typically used as a soil substitute in hydroponic

systems. Also, clay was selected by the Studio because they had

experimented their use in other projects.

To accommodate the size and geometry of potential spaces available for

conducting the pilot study, multiple wetland bed configurations using

temporary structures were considered, including high aspect ratio (up to

1:20) rectangular beds with sloped bottoms, elongated rectangular beds

that spiraled down from the top of a circular mount, multiple wetland

beds in-series. Multiple-bed-in-series using rectangular fiberglass tanks

were selected in the end. This option would allow the Studio to construct

the systems using their existing contractor, accommodate the space

limitations at the site, and allow reuse of materials after the pilot study is

complete.

1.5 Study Objectives

To evaluate the performance of HSSF wetland systems for treatment of

dry-weather LAR water, a pilot study (study) was conducted. Three HSSF

wetland treatment systems were designed and built between June and

September 2015. The primary objectives of this study were:



1. To demonstrate that HSSF wetlands were capable of treating LAR

water to meet 2011 Guidelines for aboveground non-potable water

uses;

2. To evaluate and compare the treatment performance of three

different media types with respect to FIB, turbidity, organics, and

nutrient removal; and

3. To determine the hydraulic retention time (HRT) required to achieve

optimal treatment performance.

Findings from this study will provide the design basis for scale-up. They will

support the use of HSSF wetland systems for treatment of dry-weather

runoff from the LAR and other rivers in similar urban regions for non-potable

water use. These results will also provide data to support the use of wetland

systems for treatment of dry-weather runoff for bacteria TMDL Marine REC-

1 compliance purposes.

The organization of this report is as follows:

Section 2: Treatment Performance

Section 3: Hydraulic Retention Time

Section 4: Capital and O&M Costs

Section 5: Vegetation Coverage

Section 6: Conclusions.



2. TREATMENT PERFORMANCE

2.1 Indicator Bacteria

Indicator bacteria are the primary biological contaminant of concern in

LAR water in the previous water quality sampling and testing effort as

described in Section 1.3. As such, indicator bacteria in water samples

collected from the LAR, the influent to the wetland systems (IN), and the

effluent of wetland cells 1, 2, 3, 5, 8, and 9, were analyzed. The total

coliform, fecal coliform, and enterococcus results for these locations are

presented in Figures 2-4, respectively.

Note: Error bars represent the standard deviation of the geometric mean of n= 4- 8 samples.

Figure 2 Total coliform geometric mean concentration for samples collected at

selected locations

As shown in Figures 2-4, indicator bacteria concentrations in the LAR water

were variable. Although the geometric mean was below the limits

specified in the 2011 Guidelines and the bacteria TMDL Marine REC-1, their

single sample concentrations did not consistently meet these two



requirements. For example, total coliform concentrations in the LAR water

samples were measured in the range between 2 and 16,000 MPN/100mL

during the four sampling events performed and one of them exceeded

the 10,000 MPN/100mL limit.

Note: Error bars represent the standard deviation of the geometric mean for n=4-8 samples.

Figure 3 Fecal coliform geometric mean concentration for samples collected at

selected locations

This results showed that total coliform and fecal coliform concentrations in

IN (i.e. wetland influent after storage) were 93% and 87% lower than the

LAR, respectively (Figures 2-3). This suggests that storage of LAR water prior

to treatment provide reductions, although such reductions were not

statically significant based on a t-test (p-value=0.16>0.05 for total coliform;

p-value=0.24>0.05 for fecal coliform). In contrast, a decrease in

enterococcus concentration was not observed after storage. This

observation is consistent with other studies where enterococci have been

shown to be more persistent in aquatic environments compared to



coliform bacteria (Davies, C.M. et al, 1995;Anderson, K.L., Whitlock, J.E. &

Harwood, V.J., 2005).

Note: Error bars represent the standard deviation of the geometric mean for n=4-8 samples.

Figure 4 Enterococci geometric mean concentration for samples collected at

selected locations

Reduction in total coliform, fecal coliform, and enterococcus

concentrations after one wetland cell treatment was observed. The

percentage reduction ranges were 80-92% (effluent geomean = 3.6 - 10.5

MPN/100mL), 60-70% (effluent geomean = 1-1.3 MPN/100mL), and 88-97%

(effluent geomean = 1.2-4 MPN/100mL) for total coliform, fecal coliform,

and enterococci, respectively. However, these reductions were not

considered to be significant according to a t-test (p-value=0.16 for total

coliform>0.05, p-value=0.24 for fecal coliform >0.05). The t-test results

could have been a result of relatively low IN concentrations, the variability

in the data, and the limited number of samples taken.



The effect of providing additional treatment (i.e. with longer HRT) after the

first wetland cell with respect to indicator bacteria removal was

evaluated. The data suggest that additional treatment provide little to no

observable bacterial removal benefits for all the three systems. For the

coconut coir wetland, indicator bacteria removal was observed to be

optimal after one cell. For the gravel and clay pellet wetlands, adding two

more wetland cells was shown to provide negligible improvement. It is

worth pointing out that the treatment system was unable to consistently

attain an effluent total coliform concentration of at or below 2

MPN/100mL (i.e. the 2016 Guidelines requirements) during the sampling

period. This is not surprising because total coliform is an environmental

indicator and can be found in surface water and soil. Nevertheless, to

attain the prescribed effluent quality consistency for compliance,

disinfection of effluent after treatment is necessary.

2.2 Physical and Chemical Water Quality Parameters

pH, turbidity, and conductivity were identified as the primary physical and

chemical water quality parameters of concern in the 2015 Report

(Geosyntec Consultants, 2015). These three parameters, in addition to

others listed in Tables 1-2, were characterized through field measurements

and laboratory analysis of grab samples. The results are summarized in

Tables 1-2. LAR water and IN had an average pH of 7.7±1.2 and 7.9 ±0.3,

respectively. The wetland processes buffered the pH to near neutral,

ranging between 6.8±0.1 and 7.0±0.2. These results were consistent with

those reported by other researchers (Kadlec, R.H. & Wallace, S.D., 2009).

Total suspended solids (TSS) and turbidity (a surrogate for TSS) were

measured at the selected locations and the results at these locations are

presented in Figures 5-6, respectively. LAR water contained an average

TSS and turbidity of 18 mg/L and 3 NTU, respectively. Both exceeded the

limits of 10 mg/L TSS and 2 NTU turbidity as stipulated in 2016 Guidelines

(Figure 5). Storage was shown to provide as much as 90% TSS reduction on

average, resulting in an average IN TSS of 1.8 mg/L. All effluent TSS levels

were consistently well-below the 10mg/L TSS. Consistent with the TSS results,

storage provided an average of 80% of turbidity reduction, resulting in an

average IN turbidity of 0.6±0.1 NTU, below the 2 NTU limit (Figure 6). The

reduction was described as significant per a t-test (p-value=0.04<0.05).



Recognizing the relatively low average IN TSS and turbidity levels, any

additional reduction gained through wetland treatment was expected to

be limited. Both gravel and coconut wetlands were shown to have further

reduced TSS levels consistently to below the detection limit of 0.5 mg/L. It

is noted that detectable levels of TSS were measured in all clay pellet

wetland effluent samples. These average values were maintained at no

more than the average IN TSS level of 1.8 mg/L, thus these were still

considered as low.

Note: Error bars represent the standard deviation of n=4 samples.

Figure 5 Average total suspended solids at selected locations along the treatment

systems

As for turbidity, both gravel and clay pellet wetlands maintained an

average of no more than the IN turbidity of 0.6 NTU. Based on the slight

turbidity increase detected in Cell 2 of the clay pellet wetland and

coupled with the detectable TSS levels in effluent samples in the clay

pellet wetland, the gravel wetland provided more consistent turbidity and

TSS removal in comparison.

It is noted that effluent turbidity levels in other coconut wetland effluent

samples (Cells 2, 3, 5, 8, and 9) rose with the increasing number of wetland

cells (i.e. HRT, see Figure 6). The causes had yet to be investigated, but

media leaching was thought to be one of the main potential causes. Even



though the average turbidity levels were below the 2 NTU requirements for

all effluent samples, the coconut coir wetland was considered to have the

poorest turbidity removal performance compared to the other two

wetlands.

Note: Error bars represent the standard deviation of n= 4-12 samples.

Figure 6 Average turbidity at selected locations along the treatment systems

Conductivity, a surrogate for measuring total dissolved solids (TDS), was

another contaminant of concern identified in a previous study (see

Section 1.3). High conductivity can be detrimental to plant health and

thus it is prudent to maintain the conductivity level at a reasonable level

based on the end use. The results show that the average LAR conductivity

level was 1,061 µS/cm, above the recommended MCL of 900 µS/cm but

below maximum MCL of 1,600 µS/cm (Figure 7) as specified in the 2016

Guidelines. Slight elevated average IN conductivity (1,122 µS/cm) could

have been a result of evaporation during storage.

Measurable changes in effluent conductivity was observed after the

wetland treatment processes. As shown in Figure 7, conductivity levels in

the gravel and clay pellet wetlands generally followed a similar upward

trend and increased with HRT (cell 9, gravel = 1,312 µS/cm and clay pellet

= 1,256 µS/cm). Conductivity in the coconut coir wetland effluent



decreased with increasing HRT (cell 9 = 968 µS/cm). This striking difference

between the gravel and clay pellet wetlands (using inorganic siliceous

minerals) and the coconut coir wetland (using organic cellulose materials)

is hypothesized to be stemmed from the biochemical environments in

these media as supported by the oxidation-reduction potential (ORP)

data.

Note: Error bars represent the standard deviation of n=8 samples. MCL = CA Secondary Maximum Contaminant

Levels.

Figure 7 Average conductivity at selected locations along the three treatment systems

The ORP data (Figure 8) showed that the ORP levels in the coconut coir

wetland were much lower than the other two wetlands with an average

of -280 mV were measured at the selected locations. The average effluent

ORP for the gravel and clay pellet wetlands were +16 mV and +41 mV,

respectively. These results suggest that the biochemical conditions in the

coconut coir wetland was highly reduced; while the other two were

slightly oxidized. A reduced environment favors anaerobic processes,

such as metal precipitation, fermentation, and sulfate reduction. The

decrease in conductivity, increase in organics (total organic carbon

(TOC), chemical oxygen demand (COD), and five-day biochemical



oxygen demand (BOD5)), and reduction in sulfate (see Table 1) with

increase in hydraulic retention time suggest these processes took place in

the coconut coir wetlands.


Figure 8 Average oxidation reduction potential (ORP) at selected locations along the

three wetland systems

Consistent with the difference in the ORP results, similar water quality

changes were not observed in the gravel and clay pellet wetlands. For

example, these two wetlands were shown to provide organics reduction

(TOC, COD, and BOD), while no conductivity reduction was observed.

Elevated effluent conductivity compared to IN, which could be a result of

water loss due to evapotranspiration (Kadlec, R.H. & Wallace, S.D., 2009).

Biodegradable organic concentrations in the LAR and other selected

locations were measured. The average BOD5 levels for LAR and IN were

2.8 mg/L and 1.8 mg/L, respectively, well below limit of 10 mg/L as

specified in the 2016 Guidelines (Figure 9). This shows that storage

provided slight BOD5 reduction. After treatment using two wetland cells,

BOD5 concentrations in both gravel and clay pellet wetlands were



reduced to below detection limit of 1 mg/L and remained at the same

level after water passed through additional seven wetland cells.

As noted previously, BOD5 concentrations in the coconut wetland were

evaluated with measurements collected from cells 8 and 9 exceeding 10

mg/L. This gave an overall increase of 88% BOD5 at cell 9 compared to IN

(Figure 9). Consistent with the BOD5 results, an ascending trend was also

observed in COD and TOC results. These BOD5 observations suggest that

controlling the HRT in the coconut coir wetland would be crucial to limit

organic increases and long HRT should be avoided.


Figure 9 Average BOD5 at selected locations along the treatment systems

Change in nitrate concentrations was observed in this study. LAR water

contained an average nitrate concentration of 4 mg/L as N which was

below the Secondary MCL limits as specified in the 2016 Guidelines.

Storage did not provide reduction benefits. After two cells of wetland

treatment, 99% of nitrate was removed and the concentration remained

unchanged in increasing in hydraulic retention time as expected (Figure

10).



Note: Error bars represent the standard deviation of n=4 samples. MCL = California Maximum Contaminant

Levels.

Figure 10 Average nitrate concentration at selected locations along the three wetland

systems



3. HYDRAULIC RETENTION TIME

The HRT of each treatment system was determined theoretically (void

space divided by flow rate) and empirically (using rhodamine WT (RWT)

dye tracer) (Table 3). The influent flow rate of each treatment system was

set to approximately 0.5 liter per minute (lpm) to attain a theoretical HRT

of one day per cell. The empirical HRT was calculated based on the time

required for the RWT dye to exit the cells.

When calculating the HRT, a RWT mass recovery of at least 80% must be

attained (Headley, T.R. & Kadlec, R.H., 2007). As shown in Table 3, tracer

test results from gravel and clay pellet wetlands met such a requirement.

The RWT masses recovered from these two wetlands were greater than

100%, which could be attributed to evaporation and/or instrumentation

errors (e.g. RWT sensors and flow meters). For the coconut coir wetland,

only 12% of RWT mass was recovered, and thus an empirical HRT for a

typical coconut coir cell could not be determined. The low tracer

recovery could be due to the sorption of RWT onto the organic coconut

coir media (Lin, A.Y.-C. et al, 2003).

Table 1 Mean and Theoretical Hydraulic Retention Time

Tracer Tests Theoretical

HRT, day per

cell

Measured

Mean HRT,

day per cell

Tracer

Volume, mL

Dye

Recovery

Initial Dye

Detection,

hr

Gravel 1.85 1 123% 13.10 0.80

Coconut

coir

Cannot Be

Determined 4 12% 0.83 1.08

Clay

Pellet 1.66 2 112% 6.77 0.93

The normalized effluent RWT concentrations from cell 1 of the gravel and

clay pellet wetlands are shown in Figure 11. The flow of the RWT in these

two cells can be described as dispersed based on the shape of the

curves. Multiple peaks observed in both wetlands suggest the presence



of multiple flow paths (Levenspiel, O., 1999). This observation is consistent

with the design of the wetland where multiple holes were predrilled into

the PVC pipes placed horizontally across the wetland bed.

Figure 11 RWT effluent concentration for the gravel and clay pellet wetlands

The calculated HRTs for the gravel and the clay pellet cells were 1.85 and

1.66 days per cell, respectively. They were longer than the theoretical

hydraulic retention time of approximately one day per cell. The longer

than expected HRTs could be attributed to the presence of extensive

plant roots in the wetland cells that were not accounted for calculating

the theoretical HRT. Extensive root systems alter flow paths and may

create stagnant zones to impede flow (Kadlec, R.H. & Wallace, S.D., 2009).

Regarding the tracer test performed at the coconut coir cell, a relatively

short RWT detection time of 50 minutes was recorded. This could be a result

of a combination of high hydraulic conductivity of coconut coir (Abad,

M. et al, 2005) and the presence of short circuiting in the cell (Levenspiel,

O., 1999). Despite the relatively short HRT, treatment performance of the

coconut coir wetland for indicator bacteria and nitrate removal did not

seem to be affected and the effluent concentrations were comparable

to the gravel and clay systems (see Section 2).



4. VEGETATION COVERAGE

Plant species selected and planting layout were identical in all the

wetland cells. After one year of operation, vegetation coverage and size

in all the cells are shown in Figure 12. Vegetation coverage and size

variation in the gravel and clay pellet wetlands were similar with the first

cells having the largest plant sizes and densest vegetation coverage;

while the thinnest coverage and smallest plants were found in the last cells

(A9 and C9). Such a decrease in plant size and coverage could have

been a result of geochemical composition variation in the water, but

further analysis would need to be conducted to confirm this.

Vegetation coverage and size change in the coconut coir wetland

system was noticeably different from the other two wetland systems. The

vegetation coverage, size, and coloration changed abruptly in the mid-

section of cell 1. The plant size remained relatively small with little to no

noticeable difference from cells 2 to 9. The small plant size in the coconut

wetland cells could be related to the presence of highly reduced

conditions (i.e. highly negative ORP). It has been reported that such

conditions cause oxygen stress in plants, affecting photosynthetic

activities and plant growth (DeLaune, R., Pezeshki, S. & Pardue, J.,

1990;Bandyopadhyay, B. et al, 1993). Based on the above observations,

using a relatively short HRT would be crucial for maintain plant health, in

addition to controlling effluent organic concentrations (Section 2.2).



Figure 12 Vegetation coverage of individual wetland cells in the three wetland systems.

It is noted that water flow from left (influent) to right (effluent). The white arrow mark the locations where untreated water flows into the wetland systems, while the blue arrows mark effluent discharge points.

c) Clay Pellet Wetland

b) Coconut Coir Wetland

a) Gravel Wetland

C1 C2 C3 C4 C5 C6 C7 C8 C9

B1 B2 B3 B4 B5 B6 B7 B8 B9

A1 A2 A3 A4 A5 A6 A7 A8 A9



5. CAPITAL AND O&M COSTS

The annual capital and O&M costs for deploying these wetland systems

were estimated using the material and O&M costs incurred during the

study. Based on the findings presented in Section 2-3, it was determined

that treatment systems consisting of three cells would be required to

provide sufficient redundancy for both the gravel and clay pellet media.

The option to use coconut coir as a soil medium was excluded due to its

limitation. The BRBC project would provide the water diversion system and

effluent storage at the Studio site, costs for water delivery and storage

were therefore excluded from the cost estimates presented in this section.

5.1 Capital Costs

The capital costs for a single wetland cell and a single treatment system

were estimated for the gravel and clay pellet systems for comparison. The

costs of a single cell were assumed to be comprised of a fiber glass tank,

metal frames for creating an elevation difference between tanks,

plumbing for influent flow distribution and effluent; wetland vegetation,

media; and labor costs for assembly. The costs of a treatment system

include plumbing for influent distribution, effluent collection, and

connections among the wetland cells; pumps for water transfer and flow

distribution; and labor for system installation.

System assembly and installation were assumed to be conducted by a

contractor who would provide all field equipment, and thus equipment

rental was not necessary. The labor rate of $90 per hour per person was

assumed. It was assumed that a total of 90 hours of labor would be

sufficient to assemble a single wetland cell. An additional four hours of

labor effort was required for installation of pumps and other plumbing

work. A total of 61 hours of labor would be needed to install a system (i.e.

one wetland system with three cells). For three systems connected in

parallel with a single inflow, it was assumed that a total of 175 hours of

labor would be required. A 15% contingency was also assumed. Table 4

summarizes the total capital costs for installing one and three three-tank

in-series systems.



Table 2 Capital costs for one and three three-tank in-series systems

Media Total capital Costs,

$/system

One System (up to three

wetland cells)

Gravel $17,000

Clay Pellet $19,000

Three Systems (up to three

wetland cells per system)

Gravel $44,000

Clay Pellet $50,500

5.2 O&M Costs

O&M activities for treatment wetlands typically involve pretreatment

maintenance (e.g., screen filter replacement), pump maintenance,

vegetation trimming, pest control, and routine site walks to ensure that the

treatment system is in good working order. During the study period, algal

fouling in the plumbing system was observed due to the abrupt change

in LAR water quality. As a result, additional cleaning was conducted to

prevent clogging. Also, it was assumed that sweeping would be required

to maintain site cleanliness. Based on the above, approximately 55 hours

of labor per annum were assumed to be necessary to perform these

activities. The O&M cost estimates for one and three three-tank in-series

systems are presented in Table 5. These cost estimates are expressed in

terms of annual costs.

Table 3 Annual O&M costs for one and three three-tank in-series systems

Labor Effort,

hours/year

O&M by Onsite

Staff, $/year

O&M by

Contractor, $/year

One System 88 4,080 4,960

Three Systems 154 7,200 8,740

5.3 Total Annual Costs

The total annual cost to provide a wetland system (gravel or clay pellets)

is presented in Table 6. To calculate the annual operating costs, a useful

lifetime of 15 years for each system and a salvage value of zero at the end

of its lifetime with a uniform rate of depreciation were assumed. The results



show that some economy of scale could be achieved if more systems

were installed. Also, additional cost saving could be provided by retaining

onsite personnel to perform the O&M work.

Table 4 Annual operating costs for one and three three-tank in-series systems

Media O&M by Onsite

Staff, $/year

O&M by Contractor,

$/year

One System (up to

three wetland cells)

Gravel $5,200 $7,900

Clay Pellet $5,400 $8,300

Three Systems (up

to three wetland

cells per system)

Gravel $8,300 $11,700

Clay Pellet $8,500 $12,100



6. CONCLUSIONS

A pilot study was conducted to evaluate the treatment performance of

modular and compact horizontal subsurface flow (HSSF) wetlands for

treatment of Los Angeles River (LAR) dry-weather runoff for aboveground

non-potable uses. Three systems, each with different media types (gravel,

coconut coir, and clay pellets), were tested. Water quality analysis

revealed that LAR water contained levels of indicator bacteria exceeding

both the LACDPH 2011 and 2016 Guidelines for aboveground non-potable

uses. LAR water contained TSS and turbidity levels that exceeded the 2016

Guidelines. Storage of water prior to treatment was shown to reduce total

and fecal coliform, turbidity, TSS, and organics. Turbidity and TSS were

reduced to below the limits specified in the 2016 Guidelines. Storage,

however, did not reduce other contaminants, such as enterococcus,

nitrate, and TDS.

These wetlands reduced and maintained indicator bacteria

concentrations to levels that complied with the 2011 Guidelines

requirements without the use of disinfection. Indicator bacteria

concentrations in effluent had an average of 10 MPN/100mL or lower after

one cell of treatment and it was maintained at approximately the same

levels throughout the treatment processes1. Under the more stringent 2016

Guidelines, disinfection would need to be used to ensure that water

quality objectives for bacteria were consistently met. However, the

wetland systems were effective in reducing organics (e.g. BOD5 and COD)

and nitrate. Based on the water quality results and adding redundancy to

the system, it was determined that three cells per system should be used

in future designs.

Gravel, coconut coir, and clay pellets have different physical

characteristics. Of these three, coconut coir has the lowest density which

makes it a better material for rooftop installation where the weight of the

system is of a concern. However, coconut coir may cause issues including

fine material leaching, dissolved organic concentration increases and

odor when inappropriate HRT is used. On the other hand, gravel has the

highest density which makes it a less desirable material for rooftop

1Bacteria concentrations can fluctuate across a broad range (2MPN/100mL->10,000MPN/100mL), thus the

increases were considered as small from <10 MPN/100mL to <20 MPN/100mL



installation. However, it is the preferred HSSF media compared to clay

pellets due to its lower material cost, easy access, higher material integrity,

and lack of buoyancy.

This study demonstrated that influent storage of LAR water coupled with a

HSSF wetland could be an effective option for the BRBC project. This

wetland design approach can be easily integrated into commercial,

industrial, and residential properties that have stormwater capture

capability to provide alternative water supply for onsite non-potable uses.

Additionally, other larger-scale stormwater capture projects for non-

potable uses during dry weather could also benefit from the treatment

approach evaluated in this pilot study. Further investigation should be

performed to determine the use of this treatment approach beyond LAR

dry-weather flow in urban areas. These capture, treatment, and use

activities can help diversify local water sources and foster greater water

sustainability.



7. REFERENCES

Abad, M., et al, 2005. Physical properties of various coconut coir dusts

compared to peat. HortScience, 40:7:2138.

Anderson, K.L., Whitlock, J.E. & Harwood, V.J., 2005. Persistence and

Differential Survival of Fecal Indicator Bacteria in Subtropical Waters

and Sediments. Applied and Environmental Microbiology, 71:6:3041.

Bandyopadhyay, B., et al, 1993. Influence of soil oxidation-reduction

potential and salinity on nutrition, N-15 uptake, and growth of Spartina

patens. Wetlands, 13:1:10.

Dallas, S. & Ho, G., 2005. Subsurface flow reedbeds using alternative

media for the treatment of domestic greywater in Monteverde, Costa

Rica, Central America. Water Science and Technology, 51:10:119.

Davies, C.M., et al, 1995. Survival of fecal microorganisms in marine and

freshwater sediments. Applied and Environmental Microbiology,

61:5:1888.

DeLaune, R., Pezeshki, S. & Pardue, J., 1990. An oxidation-reduction

buffer for evaluating the physiological response of plants to root

oxygen stress. Environmental and Experimental Botany, 30:2:243.

Geosyntec Consultants, 2013. LA River Water Reuse

Opportunities/Requirements – Irrigation, Los Angeles.

Geosyntec Consultants, 2015. Bending the River Back into the City

Project Water Quality Data Summary Los Angeles, CA

Headley, T.R. & Kadlec, R.H., 2007. Conducting hydraulic tracer studies of

constructed wetlands: a practical guide. Ecohydrology &

hydrobiology, 7:3:269.

Idris, S.M., et al, 2012. Performance of the giant reed (Arundo donax) in

experimental wetlands receiving variable loads of industrial

stormwater. Water, Air, & Soil Pollution, 223:2:549.

Kadlec, R.H. & Wallace, S.D., 2009 (2nd). Treatment wetlands. CRC Press,

Boca Raton, FL.

LACDPH, 2016. Guidelines for Alternate Water Sources: Indoor and

Outdoor Non-Potable Uses.

Levenspiel, O., 1999. Chemical reaction engineering. Industrial &

engineering chemistry research, 38:11:4140.

Lin, A.Y.-C., et al, 2003. Comparison of rhodamine WT and bromide in the

determination of hydraulic characteristics of constructed wetlands.

Ecological Engineering, 20:1:75.

McMillan, 2016. Model S-111/S-112/S-114 Liquid Flow Meters.

<http://www.mcmflow.com/shop/index.php/model-s-111-s-

114.html#prettyPhoto>, September 1.



Sheoran, A. & Sheoran, V., 2006. Heavy metal removal mechanism of

acid mine drainage in wetlands: a critical review. Minerals

engineering, 19:2:105.

Tanaka, N., Karunarathna, A.K. & Jindasa, K.B.S.N., 2008. Effect of

coconut coir-pith supplement on nitrogen and phosphate removal in

subsurface flow wetland microcosms. Chemistry and Ecology, 24:1:15.

Terzakis, S., et al, 2008. Constructed wetlands treating highway runoff in

the central Mediterranean region. Chemosphere, 72:2:141.

US Army Corps of Engineers, 2012. Donald C. Tillman Water Reclamation

Plant Multi-Use Facility Project Sepulveda Dam Basin - Notice of

Preparatin Los Angeles County

US Army Corps of Engineers, 2013. Los Angeles River Ecosystem

Restoration Integrated Feasibility Report, Los Angeles County

USEPA Region IX, 2012. Long Beach City Beaches and Los Angeles River

Estuary Total Maximum Daily Loads for Indicator Bacteria.



APPENDICES



APPENDIX 1- WATER QUALITY RESULTS

Table 5 Physical and Chemical Water Quality Parameters Measured in the Field

Location Water

Quality

Objectiv

e

LAR IN Gravel Coconut Coir Clay Pellets Effluent

Tank

A1 A2 A3 A5 A8 A9 B1 B2 B3 B5 B8 B9 C1 C2 C3 C5 C8 C9

pH 6-8 7.7±1.2 7.9±0.3 7±0.2 6.9±0.2 6.9±0.2 7±0.2 6.9±0.3 6.9±0.4 6.9±0.3 6.8±0.1 6.8±0.1 6.8±0.1 6.9±0.1 6.8±0.1 6.9±0.1 6.8±0.1 6.9±0.1 6.9±0.1 6.9±0.1 6.9±0.3 7.5±0.1

ORP1, mV NA 158

±115

-31±82 5±150 20±168 24±190 28±208 6±210 10±227 -274

±23

-294

±26

-295

±24

-304

±27

-285

±25

-232

±51

42±123 15±121 50±134 63±144 48±154 28±156 -21±108

DO2, mg/L 9.8±0.5 6.3±1.2 0.7±0.3 0.8±0.2 1.5±0.5 1.8±0.3 1.5±1 1.9±1.4 0.4±0.3 0.3±0.1 0.4±0.1 0.3±0.1 0.4±0.1 0.6±0.1 0.9±0.3 1±0.4 1.2±0.3 1.7±0.4 1.9±0.6 1.6±0.3 7.3±0.2

Conduct-

ivity, µS/cm

1,600 1061

±37

1122

±43

1096

±60

1151

±72

1212

±75

1291

±111

1300

±146

1312

±137

1069

±63

1067

±74

1078

±76

1021

±103

980

±52

968

±41

1102

±60

1145

±81

1186

±109

1260

±158

1243

±164

1256

±160

1320

±98

Turbidity,

NTU3

2 2.9±0.8 0.6±0.1 0.5±0.5 0.3±0.1 0.4±0.3 0.2±0.1 0.2±0.1 0.2±0.1 0.6±0.1 0.9±0.3 1.2±0.3 1.4±0.4 1.3±0.2 1.8±0.2 0.3±0.1 0.7±0.9 0.3±0.1 0.2±0 0.3±0.2 0.3±0.2 0.3±0.1

1Oxidation-reduction potential. 2Dissolved oxygen. 3Nephlometric Turbidity Unit. Red fonts indicate exceedance of regulatory limits. The number of measurements taken is n=6



Table 6 Physical and Chemical Water Quality Parameters Measured in the Laboratory

Criteria Gravel Coconut Coir Clay Pellet

Water Quality

Parameters MCL* LAR Influent A2 A8 A9 B2 B8 B9 C2 C8 C9

TOC1, mg/L NA 10.9±9.5 6.6±0.5 5.1±0.1 4.2±0.3 4.5±0.6 6.6±0.6 12.5±1.3 16±3.5 5.1±0.5 4±0.1 4±0.3

BOD52, mg/L 10 2.8±1.3 1.8±1 ND 1.4±0.7 ND 6.2±2.1 13.4±4.6 17.4±6 ND ND 1.3±0.6

COD3, mg/L NA 26±15.3 17.5±3.7 11±8.5 10.3±10.5 8.5±7 29.5±2.5 59.5±12.4 63.8±15.8 9.8±6.2 6.5±3 20.3±14.9

Ammonia, mg/L-N NA 0.2±0.2 0.2±0.1 0.1±0.1 0.1±0 0.1±0 0.1±0 0.1±0.1 0.1±0 0.1±0.1 0.1±0 0.1±0

Nitrate, mg/L-N 10 4.13±1.08 5.03±0.31 0.19±0.15 ND ND ND ND ND 0.05±0.04 ND ND

Nitrite, mg/L-N 1 0.37±0.19 0.43±0.13 ND ND ND ND ND ND ND ND ND

Orthophosphate, mg/L-

P NA

0.35±0.3 0.45±0.38 ND ND ND ND ND ND 0.17±0.08 0.53±0.41 0.36±0.29

Hardness, mg/L-CaCO3 NA 225±17.3 220±8.2 270±8.2 352.5±15 367.5±37.7 230±18.3 202.5±15 200±29.4 257.5±9.6 367.5±42.7 355±37

Arsenic, mg/L 0.01 0.005±0.003 ND ND ND ND 0.004±0.002 0.003±0.001 0.005±0.003 0.004±0.002 0.006±0.002 0.006±0.003

Copper, mg/L 1.0 0.026±0.022 0.01±0.005 0.004±0.002 0.005±0.002 0.007±0.002 ND ND 0.012±0.02 0.008±0.003 0.016±0.003 0.053±0.072

Chromium, mg/L 0.05 ND ND ND ND ND ND ND ND ND 0.002±0.002 ND

Selenium, mg/L 0.05 ND 0.004±0.002 0.004±0.002 ND ND ND ND ND ND ND 0.004±0.003

Zinc, mg/L 5.0 0.06±0.02 0.08±0.02 0.01±0.01 ND 0.01±0 ND ND 0.03±0.04 0.01±0 ND 0.01±0.01

Boron, mg/L 1.0 0.49±0.01 0.47±0 0.5±0.03 0.5±0.08 0.53±0.1 0.43±0.02 0.36±0.04 0.27±0.03 0.52±0.01 0.58±0.06 0.57±0.06

Magnesium, mg/L NA 19.5±0.7 19.7±0.6 20.7±0.6 22.3±0.6 23.7±2.1 19.3±1.2 19.3±1.5 22.3±2.5 21.3±0.6 25.7±1.5 26.3±1.5

Calcium, mg/L NA 54.5±6.4 56.3±2.1 77±1.7 106.7±5.8 113.3±5.8 61.3±3.5 48.3±5.1 39.3±6.7 69.3±2.1 116.7±5.8 106.7±5.8

TSS4, mg/L 10 18±6.1 1.8±1.2 ND ND 0.4±0.4 ND 0.4±0.4 0.5±0.4 1.8±1.9 0.5±0.4 0.4±0.4

*Maximum contamination level requirements for aboveground non-potable uses. 1Total organic carbon. 2Five-day biochemical oxygen demand. 3Chemical oxygen demand. 4Total suspended solids. NA means not

applicable. Red fonts indicate exceedance of regulatory limits. The number of samples collected is n=4



APPENDIX 2 - RAINWATER VERSUS LAR WATER QUALITY

The Studio installed rainwater cisterns to capture runoff generated from

the roof and parking structure onsite during the winter of 2015/2016. In July

2016, the Studio requested Geosyntec to collect water samples from

selected rainwater cisterns across the site to evaluate their water quality.

The water quality results for these cisterns are presented in Table 7 with LAR

water shown as a comparison.

Rainwater stored in the cisterns was less contaminated than the LAR

water. It contained lower levels of dissolved solids (conductivity and

hardness), biodegradable organics (BOD5), nutrients (ammonia, nitrite,

nitrate, orthophosphate), and metals compared to LAR water. In contrast,

zinc concentrations in rainwater were noticeably higher than that

collected from the LAR water. Elevated zinc concentrations in harvested

rainwater could be associated with the roof materials and the deposition

of suspended zinc particulates from vehicles and the environment.

Total suspended solid concentrations were also low. This could be due to

the fact that the water had been stored in the cisterns since early 2016.

This allowed time for solids and particulates to settle. BOD5 concentrations

were below the detection limit of 1 mg/L in harvested rainwater while

COD concentrations ranged from 8 to 23 mg/L. High COD suggests that

organics present were predominately oxidizable organics.

Indicator bacteria levels in rainwater were also measured. Harvested

rainwater contained very low levels of FIB. E. coli counts were below the

detection limit of 1 MPN/100mL, which is also below the 2.2 MPN/100 mL

criterion specified in the NSF standards specified in the 2016 Guidelines.

Low levels of total coliform were found in all tanks except for R4 (the

confluence point) where the total coliform count was measured at 538

MPN/100mL.



Table 7 Water Quality Data of Captured Rainwater Stored in Cisterns Onsite and LAR

Water

Criteria Rain Cistern Locations LAR

Water Quality

Parameters

LACDPH

2016

R1 R2 R3 R4 R5 R6 Avg.

TOC, mg/L NA 2.13 3.10 1.30 4.43 1.20 0.88 10.9

BOD5, mg/L 10 ND ND ND 2.43 ND ND 2.8

COD, mg/L NA 10.33 24.50 13.00 22.67 21.50 8.00 26

Ammonia, mg/L-N NA 0.05 ND ND 0.26 ND ND 0.2

Nitrate, mg/L-N 10 0.51 0.95 ND 0.57 0.73 0.61 4.13

Nitrite, mg/L-N 1 ND ND ND ND ND ND 0.37

Orthophosphate,

mg/L-P NA 0.19 ND ND 0.21 ND ND

0.35

Hardness, mg/L-

CaCO3 NA 48.67 13.50 6.25 9.30 6.35 6.60

225

Arsenic, mg/L 0.01 ND ND ND ND ND ND 0.005

Copper, mg/L 1.0 0.009 0.009 0.006 0.008 0.006 0.007 0.026

Chromium, mg/L 0.05 ND ND ND 0.002 ND ND ND

Selenium, mg/L 0.05 ND ND ND ND ND 0.006 ND

Zinc, mg/L 5.0 0.150 0.195 0.235 0.242 0.230 0.265 0.060

Boron, mg/L 1.0 0.051 0.017 0.008 0.012 0.013 0.012 0.49

TSS4, mg/L 10 2.37 ND ND 2.37 0.68 1.03 18.4

Turbidity, NTU NA 0.67 -- -- 0.37 -- 0.56

Conductivity, µs/cm 900 22.17 -- -- 29.80 -- 32.75 1061

Fecal Coliform,

MPN/100 mL NA ND -- -- ND -- -- 14.6*

Total Coliform,

MPN/100 mL 2.2 1.26 3.58 4.12 537.5 2.79 2.00 251.4*

Enterococcus,

MPN/100 mL NA 1.26 ND ND ND ND 9.64 19.2*

E. Coli, MPN/100 mL 2.2 ND ND ND ND ND ND --

Note: *Geomean values, n = 2 samples.



APPENDIX 3 - MATERIALS AND METHODOLOGY

LAR Water

This pilot study used water extracted from the LAR

at the location shown in Figure 1. Approximately

8,000 gallons of water from the LAR was extracted

and delivered weekly to the site via a water truck

(Figure 13a). The water extraction processes

involved placing a floatable pump directly on top

of the river bank where water was shallower to

prevent the pump from getting washed off (Figure

13b).

Extracted water was stored

in two 5,000-gallon storage

tanks installed in series on

site as an influent water

supply for the wetland

systems. Screening was

provided to prevent large

solids, as well as snails, from

entering the storage tanks

and eventually into the treatment systems (Figure

14a). The 5,000-gallon tank used to store LAR water

prior to distribution to the wetland systems is referred

to as the “influent tank” in this report. Water from the

influent tank was pumped to an elevated 50-gallon

intermediate tank for gravity flow distribution (Figure

14b).

Pilot Wetland Systems

Three pilot wetland systems were deployed (Figure

15). Each wetland system consisted of nine wetland

cells linked together in series. Each cell was a 7.8 ft L

x 3.8 ft W x 3.0 ft D fiberglass tank that had holes pre-set at 8 inches and 4

inches from the top of the edge of the tank on the influent and effluent

Figure 13 a) Water

truck; b) floatable pump

Figure 14 a) Influent

storage 1 at the lower

level and fabric filter

installation prior to

refilling the storage

tanks; b) influent

storage 2 and the

intermediate tank



sides, respectively. The elevation difference between these two holes

created a fixed hydraulic head of 4 inches across the length of each

wetland cell. Individual tanks were connected using one-inch clear

flexible tubing. Influent flowed into standing pipes and was subsequently

distributed over the width of the wetland via a horizontal perforated pipe

that was fixed at the bottom of each wetland cell. Effluent was collected

from another perforated pipe located about 2.5 inches below the soil

surface on center at the other end of each wetland cell. Such an

arrangement allowed for a horizontal upward flow regime within the

wetland cells as well as enhanced aeration between wetland cells.

The first eight cells of the three wetland systems were made of three

different materials: 1) 3/8 gravel (gravel wetland, A); 2) coconut coir dust

mixed with coconut coir pieces (coconut wetland, B); and 3) expanded

clay pellets (clay wetland, C). The ninth cell in the gravel (A9) and the clay

(C9) wetland systems consisted of coarse sand; while the ninth wetland

cell in the coconut wetland (B9) contained coconut coir dust. The site

layout of these three wetland systems is presented in Figure 15.

Figure 15 The pilot wetland site plan

To promote the use of native vegetation, six native Southern California

wetland plant species were selected and planted in each wetland cell.

These plant species were Schoenoplectus californicus (a.k.a. Scirpus

californicus), Schoenoplectus americanus (a.k.a. Scirpus americanus),

Juncus xiphoides, Bidens laevis, Pluchea purpurascens (PP), and Minulus

guttatus (MG). The plants were arranged to enhance aesthetics of the

Sampling Locations

Effluent Tank

Influent Tank

A1A2A3A4A5A6A7A8A9

B1B2B3B4B5B6B7B8B9

C1C2C3C4C5C6C7C8C9 Cin

INT

LAR

EFT

ee ee ee ee ee ee ee ee eenn nn nn nn nn nn nn nn nn





wetlands by planting the larger species in the middle and the dwarf

species along the edge. The layout of the plants is presented in Figure16.

Figure 16 The layout of the wetland plants in each wetland cell.

Flow Rate Control and Recording

Three McMillan S-Series Model S-111

Microturbine Flo-Meters were installed at the

influent of cells 1 of each system to measure

and record flow rates during the study period.

These flow meters were rated to measure low

flow rates in a range of between 0.013 and 10

liters per minute (lpm) with an accuracy of ±

1.0% (McMillan, 2016). Each flow meter was

paired with a Cole-Parmer multi-turn needle tip

valve to allow for precise flow control. Flow

rates were also measured manually on a

weekly basis for comparison. Figure 17 shows

the location of the valve and the flow meter

installed in the three system.

Figure 17 A flow control

and recording setup installed

at the influent of the clay

pellet wetland, C.



Water Quality Sampling and Analysis

Grab samples were collected between May and August, 2016 for

laboratory analysis and onsite measurements. Grab samples to be sent to

a certified laboratory for analysis were preserved in coolers (<4˚C). Water

quality parameters analyzed in the laboratory were FIB (total coliform,

fecal coliform, Escherichia coli, enterococci), organics (five-day

biochemical oxygen demand (BOD), total organic carbon (TOC),

chemical oxygen demand (COD), nutrients (orthophosphate, ammonia,

nitrite, and nitrate), heavy metals that are known to be commonly found

in the LAR (chromium, arsenic, selenium, copper, and

zinc), total suspended solids, boron, and hardness. FIB

analyses were conducted twice weekly, and the

remaining water quality parameters were analyzed

weekly.

Turbidity (La Motte 2020we, Chestertown, MD),

temperature, oxidation-reduction potential (ORP),

conductivity, total dissolved solids, pH (YSI ProDSS, YSI,

Yellow Springs, OH), and chlorophyll (YSI 650MDS, YSI,

Yellow Springs, OH) were measured in the field twice

weekly. The methods used for the onsite

measurements are presented in Appendix 2.

In addition to routine sampling, a suite of one-time

special sampling was conducted after the outbreak of iron bacteria

overgrowth was observed in the first three cells of the clay pellet wetland

systems (C1-3). The water quality parameter suite tested was total iron,

ferric ion, ferrous ion, sulfate, and manganese.

Hydraulic Retention Time and Tracer Tests

The theoretical hydraulic retention time (tHRT) of each cell was calculated

based on the effective porosity (ε) of the media. Both clay pellets and

coconut coir are porous materials. In the calculation, it was assumed that

fine pores in individual media did not contribute to water flow within

individual wetland cell. Presoaked clay pellets and coconut coir was

used. The measured effective porosities of gravel, coconut coir, and clay

Figure 18 An

effluent sampling port

located at the end of

each wetland cell



pellets were 34%, 36%, and 41%, respectively. The porosity data were used

to calculate the operational flow rate to yield a tHRT of one day per cell

using the relationship presented in Equation 1.

Equation 1 Operational flow rate

𝑄 =𝜀𝑉

𝑡𝐻𝑅𝑇

Where Q = operational flow rate

ε = the effective porosity

V = total volume (media + void spaces)

tHRT = theoretical hydraulic retention time

The mean hydraulic retention time in these three systems was measured

by performing rhodamine WT dye (RWT) tracer tests. RWT was selected for

its ease of use, relatively low cost, low adsorptive tendency in siliceous

materials, strong fluorescence, high diffusivity, chemical stability, and

benign character in aquatic environment (Kadlec, R.H. & Wallace, S.D.,

2009). In-situ RWT concentration detection and recording were achieved

using three YSI 6130 RWT sensors that were attached to three YSI 6820

sondes for data collection purposes. These sensors were calibrated by the

vendor according to the procedures specified by the manufacturer.

Prior to the tracer tests, the RWT background concentrations were

measured at Cells 1, 4, and 9 on a 5-minute interval for 24 hours.

Additionally, RWT sorption potential for coconut coir and clay pellet

media was evaluated by mixing the media in containers filled with a

known RWT concentration. The RWT concentrations in each container

were measured after 24 hours to determine the extent of RWT sorption.

Such information was used to adjust the quantity of dye added to the cells

to yield the desirable peak RWT concentration. It was determined that the

volume of the dye volume required were 1 mL, 4mL, and 2mL of 2.5% RWT

for the gravel, coconut coir, and clay pellet cells, respectively.

The RWT concentration change was measured and recorded at end of

the cell outlet. The sensors remained in the cell outlet until the most of the



tracer tail was captured. The data collected from the tracer tests were

used to determine the average cell hydraulic retention time using

Equation 2 below.

Equation 2 Mean hydraulic retention time of tracer in the wetland, t’, mins

𝑡′=∫ 𝐶𝑡 𝑑𝑡

∞

0

∫ 𝐶 𝑑𝑡∞

0

Where t’ = mean hydraulic retention time of tracer in the wetland, min

C = concentration exiting the wetland at time t, µg/L

t = time since addition of tracer pulse to influent port, min

The exit concentration and the time were normalized using Equations 3-5.

Equation 3 Normalized time

𝜃 =𝑡

𝑡′

Where θ = normalized time

Equation 4 Total mass concentration of mass recovered

𝐶𝑁 = ∫ 𝐶𝑑(𝜃) = ∫ 𝐶 𝑑𝑡

∞

0

𝑡′

∞

0

Where CN = total mass concentration of tracer recovered, µg/L

Equation 5 Normalized concentration

𝐸(𝜃) = 𝐶

𝐶𝑁

Where E (θ) = normalized concentration

Capital and O&M Evaluation

Capital and operation and maintenance (O&M) costs are an important

decision factor for technology selection. A common operational

challenge for HSSF wetland systems is clogging from biofouling or solids

accumulation. Improperly designed pretreatment processes often

exacerbate clogging extent and frequency. Remedy for HSSF wetlands



that are clogged with solids are either removing accumulated solids or

replacing the bed. If such maintenance activities are performed

frequently, it will add significant costs to the overall operations. The normal

O&M costs and incidental repair costs are expected to differ for these

three HSSF wetlands. Accordingly, an evaluation of the capital and O&M

costs was conducted based on the experience and lessons learned from

operating these wetland systems.

Rainwater Cisterns

Metabolic Studio installed rainwater cisterns across the property site that

captured and stored roof runoff for irrigation water use during dry weather

seasons. A total of 60,000 gallons were collected from four roof structures

during the previous rainy season. To characterize the water quality of the

stored rainwater, water samples were collected from six locations to

evaluate bacteria, organics, nutrients, and metals. Water quality

parameters tested in the laboratory were identical to those routinely

tested parameters for the pilot wetland study.

Documents

Metabolic Studio’s Pilot Wetland Study Treatment