FINAL DRAFT

 

Protecting Critical Water Resources in Dunes City, Oregon

Standards for Septic Systems and their Effluents, including Phosphorus and Nitrogen, and

_{Regulation of Phosphate Containing Products} 

 

(Photograph by Bob Anderson)

  

  Background Information Document 

And 

Draft Ordinance 

 

September 14, 2006

  

 

Table of Contents

 

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

1.         Consequences of lake over eutrophication .....................................................................3

2.         Status of lakes in Dunes City................................................................................................4

3.         The role of nutrients in lake over eutrophication ............................................................6

3.1.      The role of phosphorus ......................................................................................................... 6

3.2.      The role of nitrogen ................................................................................................................7

3.3.      Irreversibility of lake over eutrophication .........................................................................8

4.         Use of fertilizer and input of phosphorus to lakes in Dunes City ............................... 8

5.         Soil phosphorus levels and plant growth ........................................................................ 9

6.         Septic systems and input of nutrients to lakes in Dunes City .................................... 11

6.1.      Capacity of conventional septic systems to remove nutrients................................... 12

6.2.      Nutrient limits under Oregon law applicable to septic systems ................................. 13

7.         Removing nutrients from septic systems ......................................................................... 14

7.1.      Removal of phosphorus via source reduction ............................................................... 14

7.1.1.   Diversion of blackwater......................................................................................................... 14

7.1.2.   Diversion of phosphorus in detergents............................................................................ 15

7.2.      Removal of phosphorus via post-septic tank treatment technologies .................... 17

7.2.1.   Packed-bed filters containing an iron-rich media........................................................... 18

7.2.2.   Packed-bed filters containing lightweight expandable clay aggregate ................... 18  

7.3.      _{Removal of nitrogen via post-septic tank treatment technologies.............................}19

7.3.1.   The Waterloo Biofilter^TM ......................................................................................................   19

7.4.      Using post-septic tank treatment technologies in Dunes City...................................   20

8.         Release of nutrients from failing septic systems............................................................   21

9.         Monitoring of nutrient levels in treated septic system effluent ...................................   22

10.       Comparable legislation of other states ............................................................................... 22

10.1.    Legislation restricting the use of phosphate fertilizer ................................................... 22

10.2.    Legislation prohibiting the use of phosphorus containing detergents .................... 23

10.3.    Legislation regulating the release of phosphorus from septic systems .................. 23

11.       The authority of Dunes City to regulate the use of fertilizer ......................................... 24

12.       Draft Ordinance .......................................................................................................................   28  

 

INTRODUCTION                                                                                                                          [ back ]

 

On March 9, 2006, Dunes City, Oregon, adopted a Septic System Maintenance ordinance “to ensure that all onsite wastewater disposal systems, also known as sewage disposal systems or septic systems, are operated in a safe, healthful and environmentally responsible manner.”¹   The Septic System Maintenance ordinance requires homeowners in Dunes City to provide updated maps of the location of their onsite wastewater disposal systems and to regularly evaluate the integrity of their onsite wastewater disposal systems.

 

On May 11, 2006, Dunes City adopted an ordinance imposing a moratorium on land development prohibiting the acceptance of applications for partitions, subdivisions and planned

 

1  Dunes City, Ordinance number 173, Septic System Maintenance.  [ here ]

 

 

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unit developments.²      The moratorium found that “subsurface disposal system effluents contain nitrates and phosphorus that eventually migrate into groundwater and surface water sources, providing nutrients that enrich phytoplankton populations … nutrients are also introduced into surface waters through erosion and run-off  [and] both Woahink and Siltcoos Lakes have experienced episodes of rapid growth of phytoplankton populations (algae bloom) in recent years.”³

 

The moratorium granted an exemption for “development that demonstrates through site specific soil testing, development of phosphorus adsorption isotherms, and computations performed by an Oregon registered Professional Engineer that detectable levels of phosphorus in the soil from the proposed drainfield locations … will not occur for at least 100-years after installation of the system.”⁴

 

The moratorium incorporated by reference findings stating that:

 

“Residents and commercial businesses exclusively use subsurface waste disposal systems for waste treatment.  Dunes City has no septic design criteria, installation standards or ordinances of its own. It generally defers to the standards or criteria set by Lane County

or the State of Oregon that do not reflect best practices for the highly permeable soils and nearness of the lakes and wetlands. Higher standards and criteria are needed to reduce nutrient flows to ground waters, wetlands and the lakes.  ... Numerous recent advances in the efficiency of subsurface systems in removal of detrimental nutrients bring acceptable standards within reach of an adequate set of ordinances.”⁵

 

“Dunes City lacks an ordinance addressing the prohibition of fertilizer use containing phosphorus within its minimal 50-foot riparian overlay zone or within it's 1000 foot sensitive zone. And the use of these fertilizers in such close proximity to lakes, streams, and wetlands is very likely a significant source of detrimental nutrient loading to these water bodies..”⁶

 

In these findings presented here, we discuss the basis for An Ordinance to Protect Critical Water Resources in Dunes City I – Minimizing phosphorus releases from septic systems, which is given at the end of this document.  In these findings, we first lay out the approaches necessary to maintain the integrity of the water supply for Dunes City. Based on these arguments, we then propose an ordinance to establish standards for reducing nutrient flows to lakes in Dunes City.

 

The findings and ordinance were drafted with major contributions by Dr. Mark Chernaik - an environmental scientist with fifteen years of experience helping communities solve environmental problems.  In preparing the findings and ordinance, Dr. Chernaik solicited and received input and feedback from the following experts: 

 

2  Dunes City, Ordinance number 181, Moratorium on Development. [ here ] 

3  Ibid., at Paragraphs C and E.

4  Ibid., at Section 2c.

5  Ibid., at Exhibit A, paragraph 45.

6  Ibid., at Exhibit A, paragraph 56.

.

 

 

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	o	Dr. Carl Etnier, Project Scientist, Stone Environmental Inc., Montpelier, Vermont, and principal author of the June 2005 publication “Micro-Scale Evaluation of Phosphorus
		Management: Alternative Wastewater Systems Evaluation;”
	o	Dr. Anish Jantrania, Technical Services Engineer, Virginia Department of Health, Division of Onsite Sewage and Water Services, Richmond, Virginia, and co-author of the
		2006 book “Advanced Onsite Wastewater Systems Technologies;”
	o	Mark Repasky, Professional Engineer and President, Wastewater Technologies Inc., Tallahassee, Florida;
	o	Pio Lombardo, Professional Engineer and President, Lombardo Associates, Inc., Newton, Massachusetts, and author of the April 2006 publication “Phosphorus Geochemistry in
		Septic Tanks, Soil Absorption Systems, and Groundwater;”
	o	Michael Kucinski, Section Supervisor, Roseburg, Oregon Department of Environmental Quality, Onsite Wastewater Management Program;
	o	Denise Kalakay, Water Quality Specialist, Lane County Council of Governments, Eugene, Oregon.
1.		Consequences of lake over eutrophication                                     [ back ]

 

Lake over eutrophication can cause human death and illness through exposure to pathogenic microbes that proliferate in eutrophic conditions.⁷   Cryptosporidium and Plesiomonas shigelloides are pathogens that proliferate in lakes experiencing over eutrophication.⁸

Cryptosporidium oocysts are highly resistant to common disinfectants, such as chlorine, and

survive for months.  Over eutrophication of coastal dune lakes near to Dunes City has forced the Oregon Department of Human Services to issue public health advisories against exposure to water from these lakes.⁹

 

Lake over eutrophication causes chemical and microbial changes in water quality that can impart to water an obnoxious and unpalatable taste and odor.¹⁰

 

Lake over eutrophication causes overgrowth of pathogenic microbes that can reduce or eliminate recreational uses of lakes.  Overgrowth of pathogenic microbes caused by over eutrophication

_{has forced the Oregon Department of Human Services to advise closure of several coastal dune}

 

 

7  Oregon Department of Human Services “Blue-Green Algae Health Concerns in Oregon.”

http://public.health.oregon.gov/HEALTHYENVIRONMENTS/RECREATION/HARMFULALGAEBLOOMS/Pages/faqs.asp

8         U.S. EPA “Safe Drinking Water - Guidance for people with severely weakened immune systems.”  www.epa.gov/safewater/consumer/pdf/crypto.pdf; U.S. Food and Drug Administration  “Plesiomonas shigelloides.”   Pathogenic Microorganisms and Natural Toxins Handbook   http://pdf.usaid.gov/pdf_docs/PNADO152.pdf  pp56          

9  Oregon Department of Human Services “Tenmile Lakes Toxic Microcystis Bloom.”

http://public.health.oregon.gov/NewsAdvisories/Pages/index.aspx  & [http://tlbp.presys.com/page27.html

10  Davies, J.M. et al. (2004) “Origins and implications of drinking water odours in lakes and reservoirs of British Columbia, Canada.” Water Research, 38(7):1900-10, page 1900.

 

 

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lakes to recreational use.¹¹   Lake over eutrophication also reduces aesthetic values by increasing turbidity and causing discoloration.¹²

 

2.         Status of lakes in Dunes City                                                                                         [ back ]

 

More than a thousand people use water from lakes in Dunes City for domestic purposes, including for drinking.  Tens of thousands of people visit lakes in Dunes City each year to go swimming, enjoy water sports, fishing and boating and to enjoy their beauty.  Algal blooms, obnoxious and unpalatable taste and odor, increased turbidity, and discoloration have been detected during the summer in recent years in lakes in Dunes City, particularly Lake Woahink.^{13 ,}

^{14 , 15}   Cryptosporidium and Plesiomonas shigelloides have recently infected individuals consuming water from homes that take their water from lakes in Dunes City.¹⁶

 

Several studies of conditions at Lake Woahink dating back to the mid-1960s reveal a lake that is in a precarious state.

 

According to a study published by researchers from Portland State University, the trophic state of Lake Woahink had declined from the late-1960’s to the early-1990’s:

 

“This paper discusses evidence suggesting that the study lakes have become more biologically productive (eutropic), apparently as a result of human activities, and provides additional limnological information about each lake. … Increases in the rate of phytoplankton primary productivity, densities of selected zooplankton species,

sedimentation rate, sedimentary vanadium, and numbers of Cyclotella stelligera frustules all indicate that Lake Woahink has undergone significant change relative to its presettlement condition.  The primary productivity measurements made in 1992 average

1.5 times larger than the maximum rates measured during 1970-1972 (Table 2).  A comparison of data from 1991 and Malick (1970) for the total density of four zooplankton species … showed that the lowest 1991 density (15,300 m3) was almost twice as large as the highest 1968-1969 density (8,200 m3).”¹⁷

 

However, this same 1996 study failed to detect changes in Lake Woahink beyond perturbations in the relative composition, not total abundance, of lake microbes:

  

11  Oregon Department of Human Services (October 2002) “Potential recreational hazard at Mercer Lake.”

http://library.state.or.us/repository/2010/201009021114014/index.pdf

http://www.oregon.gov/DHS/ph/envtox/ma102002.shtml    http://scienceforlawyers.com/Dunes_City_Final_Report_April_10.pdf

12  Environment Canada (2001) “Nutrients in the Canadian environment,” page 13.

http://dsp-psd.pwgsc.gc.ca/Collection/EN1-11-97E.pdf             http://www.statcan.gc.ca/pub/16-002-x/2008004/tbl/water-eau/tbl002-water-eau-eng.htm

13  Dr. Doug. Larson, a limnologist studying these lakes for over thirty years, reported observing ‘toxic’ blue-green algae in Siltcoos Lake in his fly-overs in 1991. He reported to residents of Dunes City at the City Hall, January 28,  2006, and stated, in part, “... Anybody that takes their drinking water should be very concerned.”

14  Testimony of Susie Navetta before the Dunes City Council, February 20, 2006; Testimony of Mark Chandler before the Dunes City Council, March 2, 2006.

15  Testimony of Gerald Wasserburg before the Dunes City Council, March 2, 2006.

16  Testimonies of Holly H. Martin and Miffy Honda to the Dunes City Council

17  Dagget et al. (1996) “Eutrophication of Mercer, Munsel, and Woahink Lakes, Oregon,” Northwest Science, 70(special issue 2):28-38

 

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“The presence of Cyclotella stelligera in Woahink was cited by Johnson et al. (1985) as partial justification for assigning the lake to oligotrophy, yet the relative numbers of frustules from this species, already the most abundant taxon in Woahink sediments, increased by over a third between the lower strata and the 2 cm depth …, the same period of time that the lake has been apparently undergoing cultural eutrophication.  The

increase in the relative abundance of C. stelligera as this lake underwent enrichment may be an early indicator of eutrophication. …. Data for chlorophyll a and dissolved oxygen show no apparent change over time (Daggett 1994) suggesting that there was a greater shift in species composition than in total primary productivity.”¹⁸

 

A more recent study published in 2001 by researchers with the Center for Lakes and Reservoirs, Portland State University, noted additional and more serious symptoms of over eutrophication in Lake Woahink evident by 2000 that were not evident in 1994:

 

“Dissolved oxygen concentrations in the hypolimnion of Woahink Lake were generally lower than in previous years (Figure 16). The lowest concentration measured just prior to turnover was 4 mg/L. Lower concentrations were measured in the hypolimnion when turnover occurred later.”¹⁹

According to a 1999 study by the U.S. Forest Service, Siuslaw National Forest: “Eutrophication of Woahink and Siltcoos Lakes is particularly alarming since

^{development continues with neither area wide sewage nor water treatment facilities in}

this area. Currently, several housing developments around Woahink and Siltcoos lakes rely on small private water treatment facilities of varying size and effectiveness that draw their water from the lakes. Simultaneously, the condition of septic tanks around the lake varies based on age and type. Thorough site evaluations take place by Lane County officials for the installation of new septic systems which must account for soil type and proximity to the lake, but a 1972 survey of septic tanks found that 26% of all tanks within

100 feet of the lake were performing unsatisfactorily (Lane County, 1978). Where systems had failed, sewage was coming to the ground surface very near the lake and in winter almost certainly drained there. …

 

“If nutrient levels continue to increase relatively unchecked by State or County officials, problems such as those in Tenmile Lake south of this watershed will begin to take place. In Tenmile Lake, toxic algal blooms (Microcystis) have made water unsafe for drinking or recreation during certain times of year with uncertainty of its long-term effects on public safety and the viability of local tourism.”²⁰ 

 

18  Ibid.

19     Systma and Haag (2001) “Oregon Lake Watch 2000 Final Report,” Portland State University, at page 17. http://www.clr.pdx.edu/publications/files/clw_report_2000.pdf

20     U.S. Forest Service/Siuslaw National Forest (1999) “Coastal lakes watershed analysis,” at pages 48-49. http://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5244988.pdf

 

 

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3.         The role of nutrients in lake over eutrophication                                                        [ back ]

 

Lake over eutrophication is one of the most well studied ecological phenomena.  Excess input of nutrients, especially phosphorus, but also nitrogen, is always the cause of lake over eutrophication.²¹

 

3.1.      The role of phosphorus

 

Beginning in 1968, the Experimental Lakes Area Research Unit (ELA) of the University of Manitoba has conducted extensive studies on the role of nutrients as the cause of lake over eutrophication.  These studies have dramatically confirmed that phosphorus is the key nutrient that causes lake over eutrophication.  According to the ELA:

 

“Using small, natural lakes as experimental systems, scientists at the ELA were able to add various combinations of nutrients and determine which of the major plant nutrients (carbon, nitrogen, phosphorus) was the key to controlling cultural eutrophication in lakes. Over a number of years, seven different ELA lakes (227, 304, 302, 261, 226, 303, 230) were experimentally fertilized in various ways. Two of these lakes (227 and 226) were particularly important in demonstrating that phosphorus was the key nutrient for the control of eutrophication.

 

“Studies of gas exchange and internal mixing in ELA lake 227 during the early 1970's clearly demonstrated that algae in lakes were able to obtain sufficient carbon dioxide, via diffusion from the atmosphere to the lake water, to support eutrophic blooms. Other studies in the same lake demonstrated that certain blue green ‘algae’ (Cyanophytes or Cyanobacteria) were able to ‘fix’ nitrogen that had diffused naturally into the lake from the air, thereby making the nitrogen available for supporting algal growth.

 

“ELA Lake 226 was the site of a visually spectacular experiment. The lake was divided into two approximately equal portions using a plastic divider curtain. Carbon and nitrogen were added to one half of the lake, while carbon, nitrogen and phosphorus were added to the other half. For eight consecutive years, the side receiving phosphorus developed eutrophic algal blooms, while the side receiving only carbon and nitrogen did not. However, after only two years, this experiment convinced even the skeptics that phosphorus is the key nutrient. A multi-billion dollar phosphate control program was soon instituted within the St. Lawrence Great Lakes Basin. Legislation to control phosphates in sewage, and to remove phosphates from laundry detergents, was part of this program.”²²

 

Depicted on the following page is an aerial photo of divided lake showing over eutrophication in response to added phosphorus. The upper portion of the lake received added carbon and nitrogen and remained clear; the lower portion of the lake received added carbon, nitrogen and phosphorus and experienced an algal bloom.   

  

21  Carpenter, S. (2005) “Regime Shifts in Lake Ecosystems: Pattern and Variation.”

22  Experimental Lakes Area Research Unit of the University of Manitoba, Eutrophication (Nutrient Pollution). http://www.eolss.net/Sample-Chapters/C03/E2-20A-04-02.pdf

 

 

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The trophic state of a lake follows a sigmoidal dependence on phosphorus levels, meaning that as a lake becomes more eutrophied, relatively small additional inputs of phosphorus can cause a

very large shift in the lake’s trophic state.²³   In certain cases, when a lake is in a mesotrophic

state (approaching the midpoint), a small increase in phosphorus loading can abruptly shift a lake to a eutrophic state.

 

3.2.      The role of nitrogen                                                                                                   [ back ]

 

Excess nitrogen can also encourage lake over eutrophication.  According to a 2005 report of the

UK Centre for Ecology & Hydrology:

 

“Phosphorus is traditionally regarded as the primary nutrient controlling lake productivity. This belief is derived, first of all, from correlations, across a large number of lakes, between phosphorus concentration, usually expressed as total phosphorus, and phytoplankton abundance, usually measured as the concentration of chlorophyll a. A second reason for the focus on phosphorus rather than nitrogen (or carbon) is that the history of eutrophication of lakes … is related to an increase in the availability of

phosphorus rather than nitrogen. A third reason for the focus on phosphorus derives from seminal whole–lake experiments on Canadian shield lakes which demonstrated that, in these, phosphorus was the prime limiting nutrient.

 

“Nevertheless, while it is true that phosphorus is usually the main limiting nutrient in freshwaters, other resources may also be limiting on occasion. ... Furthermore, after decades of anthropogenic P loading and associated eutrophication it is likely that the number of lakes limited by nitrogen has increased. These, in addition to the lakes which might be naturally nitrogen limited, such as those with naturally high P levels, or where

 

23  Srinivasu, P.D.N. (2004) “Regime shifts in eutrophied lakes: a mathematical study.” Ecological Modelling,

179:115-130, at page 4.  http://www.ictp.trieste.it/~eee/files/wp19.pdf

 

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denitrification rates are high, suggests that the role of nitrogen in driving over eutrophication in lakes needs to be reviewed.

 

“Nitrogen is the primary or co–limiting nutrient for phytoplankton production in some lakes in North America. …. N–limitation does not appear to be confined to eutrophic lakes, and has been reported in mesotrophic lakes and in oligotrophic lakes for periods during the late summer in North America. Even where lakes are not predominately N– limited, the N–limitation of phytoplankton can occur even for short periods. …

 

“As a result of the fixation activities of cyanobacteria it is argued that P–limitation should prevail and any N–limitation should be short lived (Schindler, 1977; Howarth et

al.,1999). Nevertheless, Maberly et al. (2002) suggested that the lack of escape from nitrogen–limitation in the relatively unproductive upland lakes they studied may have resulted from environmental factors that were not favourable for cyanobacteria such as low concentrations of P, low pH and high loss rates through flushing.

 

“Although phosphorus is the main resource that limits phytoplankton growth in many lakes, there is growing evidence that suggests that in certain types of lakes, both upland and lowland, nitrogen may be the primary–limiting or co–limiting nutrient. Some cyanobacteria can fix nitrogen and so, potentially, escape from nitrogen–limitation. This may not be the only mechanism for their dominance in productive lakes with relatively low concentrations of nitrogen but there is a danger that increased phosphorus concentrations, resulting from eutrophication, may lead to greater frequency of nitrogen– limitation, furthering cyanobacterial blooms, some of which may be toxic. In upland lakes where conditions tend not to be favourable for cyanobacteria, nitrogen limitation may be frequent and the lakes accordingly sensitive to changes in nitrogen availability. Overall, it is desirable that N–reduction is carried out hand in hand with P–reduction

measures (van der Molen et al., 1998).”²⁴

 

3.3.      Irreversibility of lake over eutrophication                                                                [ back ]

 

Numerous case studies show that lake over eutrophication is often irreversible.²⁵   After a lake reaches a eutrophic state, decreased oxygen levels in the hypolimnium cause lake sediments to release more phosphorus.  Under these conditions, the lake’s sediments act as a reservoir of continued phosphorus input into the lake’s waters, establishing a dynamic that locks-in eutrophic conditions.²⁶    Therefore, additional release of phosphorus could result in the irreversible over eutrophication of lakes in Dunes City and the loss of the vital public benefits they provide.

 

_{4.             Use of fertilizer and input of phosphorus to lakes in Dunes City}                    [ back ]

 

24  UK Centre for Ecology & Hydrology (2005) “Deriving practical guidance on the importance of nitrogen in freshwater eutrophication.”       http://archive.defra.gov.uk/environment/quality/water/waterquality/diffuse/nitrate/documents/nvz-eutrophic-method.pdf [2012]

25  Carpenter, S. (2005) “Regime Shifts in Lake Ecosystems: Pattern and Variation.” Chapter 2. Regime Shifts in Lakes.  http://limnology.wisc.edu/            http://en.wikipedia.org/wiki/Regime_shift

26  Janssen, M.A. & Carpenter, S.R. (1999) “Managing the Resilience of Lakes: A multi-agent modeling approach.” Conservation Ecology 3(2): 15.  http://www.ecologyandsociety.org/vol3/iss2/art15/

 

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A report of the U.S. Forest Service, Siuslaw National Forest states:

 

“An additional source of nutrients to Woahink Lake is the runoff from lawns and driveways that lead directly into Woahink Lake. Sediment and fertilizer laden runoff from these areas are high in phosphorus and nitrogen and are key components of the eutophication now observed. Education and increased awareness of private shore owners is very important to limiting this nutrient source.”²⁷

 

A recent study of the U.S. Geological Survey in Wisconsin analyzes in more detail the contribution lawn maintenance makes to the release of phosphorus to lakes:

 

“The annual phosphorus load from the nearshore area of Lauderdale Lakes may be greater than the 430 pounds previously estimated. Using a revised median concentration of 2.3 mg/L for surface runoff from an estimated 220 acres of developed shoreline (67

percent of shoreline) within 200 feet from the edge of water, annual total phosphorus load from residential lawns could be as much as 370 pounds (assuming all of the phosphorus reaches the lake). If a delivery of 50 percent of the load is assumed, and the total surface- water load is recomputed using the surface runoff values from the previous study, the

total annual surfacewater load from the nearshore drainage area would be 620 pounds, which represents 60 percent of the total annual phosphorus input from all sources.”²⁸

 

This study also concluded that: “Runoff from lawn sites with nonphosphorus fertilizer applications had a median total phosphorus concentration that was similar to that of unfertilized sites, an indication that nonphosphorus fertilizer use may be an effective, low-cost practice for reducing phosphorus in runoff.”²⁹

 

5.         Soil phosphorus levels and plant growth                                                               [ back ]

 

According to the Oregon Extension Service:

 

“Healthy turf does not show a growth or color response to phosphorus. Contrary to the popular notion expressed in many newspapers, magazines and garden books, phosphorus does not enhance root growth of grasses unless it is added to deficient turf. Since the vast majority of lawn soils contain adequate P, supplement applications are usually wasteful.

 

“Phosphorus is best applied only when soil tests indicate it is low.  In all regions of Oregon, a soil test level above 20 ppm indicates that P is adequate and does not need to be applied.”³⁰ 

 

27  U.S. Forest Service/Siuslaw National Forest (1999) “Coastal lakes watershed analysis,”at pages 48-49    http://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5244988.pdf

28  U.S. Geological Survey (2002) "Effects of Lawn Fertilizer on Nutrient Concentration in Runoff from Lakeshore Lawns, Lauderdale Lakes, Wisconsin." USGS Water-Resources Investigations Report 02–4130. http://wi.water.usgs.gov/pubs/wrir-02-4130/wrir-02-4130.pdf

29  Ibid.

30  Oregon State University Extension Service (2005) “Fertilizing Lawns.”  http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/18906/ec1278.pdf

 

 

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This is in accord with the Extension Services of other states that have examined the relationship between soil phosphorus levels and healthy plant growth.  A publication of the University of Minnesota Extension Service depicts the following response of plants to soil phosphorus.³¹

 

 

 

According to this publication:

 

“Soil test levels are measured in a laboratory by either the Bray or Olsen procedure. The Bray procedure is usually used when soil pH is less than 7.4. The Olsen procedure is used when soil pH is 7.4 or higher. The soil test values for phosphorus which correspond to the relative levels are listed [below]:³²

 

 

             Procedure               Bray             Olsen

 

_{- - - - - - - - ppm - - - - - - -}

 

 

According to the Oregon Extension Service: “On the Oregon Coast, soils range from fine sand to subsoil clays and have a pH in the range of 5.5 (∀ 0.5).”³³   The PH should be determined in order to choose the appropriate analytical method.  Therefore, soils in Dunes City should be 

 

31 University of Minnesota Extension Service (1998) “Agronomic and Environmental Management of Phosphorus.”  http://www.extension.umn.edu/distribution/cropsystems/DC6797.html

32  Ibid.

33  Oregon State University Extension Service (2004) “Practical Lawn Establishment and Renovation.”  

http://extension.oregonstate.edu/catalog/pdf/ec/ec1550.pdf  

considered to have medium phosphorus levels if the Bray procedure shows phosphorus levels between 11-15 ppm or 8-11 ppm by the Olsen procedure.  Even at these medium soil phosphorus levels, grass growth should be at >80% of levels occurring with abundant soil phosphorus levels.

 

Moreover, the external addition of phosphate-containing fertilizer is not the only option of insuring that soils contain adequate levels of phosphorus.  Best management practices, such as returning grass clippings to a lawn by use of a mulching mower, returns phosphorus to soil, further reducing the need for any use of phosphate fertilizer.  Lawn clippings contain about 0.13 pounds phosphorus per 1000 square feet, making them excellent natural fertilizer.³⁴

 

The draft ordinance presented in Section 12 presumes that the use of phosphate fertilizer is not necessary in Dunes City. However, the draft ordinance allows homeowners in Dunes City to still use phosphate fertilizer by performing soil tests on their property that show that their soil is deficient in phosphorus.

 

Homeowners can collect soil from their property by following a simple procedure.³⁵

Homeowners can then bring or send soil samples to a laboratory for analysis of phosphorus by the Bray or Olsen procedure, whichever is appropriate.  Excluding the cost of shipping, the cost of soil testing for phosphorus is minimal.  The Central Analytical Laboratory at Oregon State University charges seven dollars per sample for testing soil phosphorus levels.³⁶

 

Under the ordinance, a test showing that soil deficient in phosphorus is not a license for a homeowner to apply any amount of phosphate fertilizer.  Instead, the application of phosphate fertilizer must “not exceed rates recommended by the Oregon State University Extension service for application to a particular plant species.”  This rate will depend on the level of phosphorus found in a soil test.  For example, if a homeowner found soil phosphorus levels of 12 ppm, then

an application of only 0.5 pounds of phosphate (as P₂O₅) per 1000 ft²  of lawn would be necessary.³⁷

 

6.         Septic systems and input of nutrients to lakes in Dunes City                            [ back ]

 

Like carbon, phosphorus and nitrogen are essential building blocks of life.  Phosphorus is a key element of DNA, and nitrogen is a key element of protein.  The human body contains about 1% phosphorus.  Phosphorus and nitrogen are in all the foods we eat and, hence, in the wastes people generate.  As a result, onsite wastewater systems inevitably receive substantial amounts of these chemical elements. 

 

34  Minnesota Department of Agriculture (2005) “Phosphorus in Lawns, Landscapes, and Lakes: An Informative Guide on Phosphorus.”  http://www.mda.state.mn.us/Global/MDADocs/chemfert/reports/phosphorusguide.aspx

35  University of Minnesota Extension Service “Lawn Soil Testing.”   http://cropandsoil.oregonstate.edu/cal/price-soil-test

36  Central Analytical Laboratory Oregon State University Soil Test Price List http://cropandsoil.oregonstate.edu/Services/Plntanal/CAL/price.htm

37  University of Minnesota Extension Service “Soil Test Interpretations and Fertilizer Management for Lawns, Turf, Gardens, and Landscape Plants Established Lawns and Turf.”    http://www.extension.umn.edu/distribution/horticulture/components/1731-complete.pdf

 

 

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6.1.      Capacity of conventional septic systems to remove nutrients                       [ back ]

 

Conventional septic tanks have little capacity to remove phosphorus.  According to a recent review:

 

“Organic wastes in the septic tank are partially digested under anaerobic conditions by microorganisms in the tank, which typically reduce biological oxygen demand (BOD) in the effluent by 30 to 50% (US EPA 2002). Nitrogen and phosphorus compounds are also transformed in the septic tank via microbially mediated processes. Most of the nitrogen and phosphorus that enters the tank in organic molecules from feces, urine, and food waste is converted to mineralized forms: organic nitrogen (urea) to ammonia and organic phosphorus to soluble orthophosphate. …. Orthophosphate is the most bioavailable and mobile form of phosphorus; therefore, conversion to orthophosphate in the septic tank has implications for subsequent steps in the wastewater treatment process.

 

“Septic tanks were not developed to remove phosphorus from wastewater. Cantor and Knox (1986) conclude that septic tanks are not highly efficient in phosphorus removal. The amount of phosphorus removed from the wastewater stream is a function of sludge accumulation in the interval between tank pumpouts. When a septic tank is pumped out, the phosphorus contained in the septage (the sludge, scum, and volume of wastewater in the tank) is removed from the wastewater treatment system. ….

 

“In a summary of Scandinavian and US sources, Refsgaard and Etnier (1998) found 3 to

5% phosphorus sequestration in septic tanks.  A recent estimate of phosphorus-removal efficiency of a conventional septic tank was developed by the Ventura Regional Sanitation District (2001) in a demonstration study of several advanced onsite sewage dispersal systems. ….  The mean influent phosphorus concentration for the duration of the test period was 3.2 mg/L … The mean effluent phosphorus concentration was 2.9 mg/L, a 9% reduction in total phosphorus. The ranges in phosphorus concentration were

2.3 to 4.5 mg/L and [only] 2.0 to 3.3 mg/L for influent and effluent, respectively. Despite substantial overlap in the ranges, these data suggest marginal phosphorus removal during normal system operation.”³⁸

 

Conventional septic tanks are not much better at removing nitrogen.  According to a recent report of the Washington State Department of Health:

 

“Removal of nitrogen from wastewater is a complex process, even for large wastewater treatment plants. Quality control of nitrogen removal processes from individual onsite wastewater systems is even more difficult to manage. Treatment systems that are most commonly used are relatively efficient in the removal of biological oxygen demand (BOD) and total suspended solids (TSS) from wastewater, but provide less than optimal removal of nitrogen (10-30 %). Most of the nitrogen is released as nitrate (NO₃^-), which   

38  Etnier, C.D., et al. (2005) “Micro-Scale Evaluation of Phosphorus Management: Alternative Wastewater Systems Evaluation.” Project No. WU-HT-03-22. Prepared for the National Decentralized Water Resources Capacity Development Project, Washington University, St. Louis, MO, by Stone Environmental, Inc., Montpelier, VT, at page 2-35. http://www.stone-env.com/water/wwres.php

 

 

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is highly mobile in the soil water. In a conventional septic tank and drainfield system organic nitrogen in household wastes is transformed into ammonia products in the anaerobic conditions of the septic tank (ammonification). When these products exit the septic tank and encounter the aerobic conditions in the drainfield, the ammonia products are biochemically transformed primarily into nitrates (nitrification). These two steps, ammonification and nitrification, occur naturally in conventional systems.”³⁹

 

According to this same report:

 

“A typical family of four using a conventional septic system can be expected to generate

20 to 50 pounds of nitrogen per year. Ten to thirty percent of this nitrogen is trapped in the septic tank as part of the sludge/scum accumulation in the tank. The nitrogen remaining in the liquid waste is transformed to nitrate when the wastewater leaves the anaerobic conditions of the septic tank and percolates through the aerobic environment of the soil portions of the drainfield. Although there is some potential for denitrification as the wastewater moves through the soil, the majority of the nitrogen produced by the family remains as nitrate loading to the soil. Drainfields installed 2-3 feet deep in soils where there is little organic matter, are relatively inefficient at removing nitrogen.”⁴⁰

 

“Untreated domestic wastewater typically contains 20 to 85 mg/L Total-N.”⁴¹

 

Because conventional on-site wastewater treatment systems are not designed to remove phosphorus or nitrogen, the use of these systems in lakeshore communities can make up the locally dominant pathway for entry of nutrients to a lake.

 

6.2.      Nutrient limits under Oregon law applicable to septic systems                        [ back ]

 

The primary function of onsite wastewater treatment systems is to protect public health by minimizing human exposure to pathogenic bacteria, of which fecal coliform is an indicator.

 

The Oregon Department of Environmental Quality (DEQ) has enacted an extensive rule that applies to onsite wastewater treatment systems throughout the state.⁴²   Under this rule, new, conventional onsite wastewater treatment systems must be designed to comply with ‘Treatment Standard 1,’ which includes the following numerical limits only:

 

• A 30-day average of less than 20 mg/L of biochemical oxygen demand (BOD); and

_{•      A 20 mg/L of total suspended solids (TSS)}

 

Thus, there are no limits under existing Oregon law that limit the release of nutrients from new, conventional onsite wastewater treatment systems. 

 

39  Washington Department of Health (June 2005) “Report to the Puget Sound Action Team: Nitrogen Reducing Technologies for Onsite Wastewater Treatment Systems.”   http://www.psparchives.com/publications/our_work/hood_canal/hood_canal/n_reducing_technologies.pdf

40  Ibid., at page 8.

41  Ibid., at page A-15.

42  Oregon Administrative Rules for Onsite Wastewater Treatment Systems, OAR Chapter 340, Division 071

 

 

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Also under this DEQ rule, some new onsite wastewater treatment systems that include a recirculating sand filter or alternative treatment technology, must be designed to comply with “Treatment Standard 2,” which includes the following numerical limits only.

 

• A 30-day average of less than 20 mg/L of biochemical oxygen demand (BOD);

_{•      A 20 mg/L of total suspended solids (TSS);}

_{•      A 30-day geometric mean of less than 400 fecal coliform per 100 milliliters; and}

_{•      A 30-day average of 30 mg/L of Total Nitrogen (TN)}

 

Although Treatment Standard 2 includes a limit on levels of nitrogen some onsite wastewater treatment systems may release, it does not include a limit on phosphorus.  Furthermore, because Treatment Standard 2 is restricted to onsite wastewater treatment systems that include a recirculating sand filter or alternative treatment technology, the limit on nitrogen levels might have minimal application to Dunes City.  We are unaware of any onsite wastewater treatment systems in Dunes City, existing or planned, that would include a recirculating sand filter or alternative treatment technology.⁴³

 

Moreover, as discussed above, typical levels of total nitrogen in septic tank influent range from

20-85 mg/L.  So, the 30 mg/L numerical limit for nitrogen in the DEQ rule, in the rare instance it does apply, does not require a substantial reduction, if any, in the amount of nitrogen released by an onsite wastewater treatment system.  Rather, it seems that the purpose of the numerical limit for nitrogen in the DEQ rule is to insure that when developers and homeowners install a new onsite wastewater treatment systems that includes a recirculating sand filter or alternative treatment technology, these systems do not increase nitrogen output over what a conventional septic system releases.

 

7.         Removing nutrients from septic systems                                                                     [ back ]

 

There are several options for removing nutrients from on-site wastewater treatment systems. What follows is a discussion of the efficacy and cost-effectiveness of these options.

 

7.1.      Removal of phosphorus via source reduction                                                             [ back ]

 

7.1.1.  Diversion of blackwater

 

Toilet wastewater (often referred to as blackwater) contributes a substantial fraction of phosphorus to onsite wastewater treatment systems.   According to the 2005 NDWRCDP Research Project Report: 

 

43  Under the DEQ rule, ‘alternative treatment technology’ is defined as ‘an alternative system,’ which in turn is defined as a system ‘for use in lieu of the standard subsurface system.’   www.deq.state.or.us/wq/rules/div071/oar071rules.pdf

OAR 340-071-0100 – Definitions.  If developers and homeowners use the post-septic tank treatment technologies for the removal of phosphorus described in Section 7.2 of this report, then DEQ would likely consider these devices to be 'add-on treatment units' rather than alternative treatment technology.        http://arcweb.sos.state.or.us/pages/rules/oars_300/oar_340/340_071.html

 

 

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“removing blackwater from domestic wastewater reduces phosphorus by 75%.”⁴⁴

 

A number of composting toilets with proven track records are commercially available, including the Clivus Multrum composting toilet,⁴⁵ the EcoTech Carousel composting toilet system,⁴⁶ and the Sun-Mar composting toilet.⁴⁷   The total estimated life-cycle cost of a composting toilet ranges from $1600-$6400.⁴⁸

 

Another option for the diversion of blackwater is the installation of a zero-discharge water recycling system.  An example of this technology is the Equaris Infinity Water Recycling System that uses a closed-loop system that eliminates the discharge of phosphorus and other pollutants typically found in septic tank effluent.⁴⁹   However, this option is relatively expensive.

According to the 2005 NDWRCDP Research Project Report, the system costs $35,000, plus

$3,000-5,000 for installation, and entails operating and maintenance costs of $400-500 per year.⁵⁰

 

7.1.2.  Diversion of phosphorus in detergents                                                                         [ back ]  

 

Banning the use of high-phosphate detergents is a simple, cost-effective means of lowering phosphorus levels in onsite wastewater treatment system effluent.  In addition to normal human wastes, high-phosphate cleaning compounds and detergents are a considerable source of phosphorus contribution to onsite wastewater treatment systems.   Many people assume incorrectly that Oregon law prohibits the sale of high-phosphate automatic dishwasher detergent (ADD).  However, Oregon law only prohibits the sale of high-phosphate laundry detergent. According to the NDWRCDP Research Project Report:

 

“In the early 1970s, when phosphorus limits for laundry detergent were set, automatic dishwashers were relatively uncommon and there was not a perceived need to severely limit or ban phosphorus in dishwashing detergents. Now that dishwashers are common in many homes, efforts are underway in several states to ban phosphorus in dishwashing detergents as well ...”⁵¹

 

 

44  Etnier, C.D., et al. (2005) “Micro-Scale Evaluation of Phosphorus Management: Alternative Wastewater Systems Evaluation.” Project No. WU-HT-03-22. Prepared for the National Decentralized Water Resources Capacity Development Project, Washington University, St. Louis, MO, by Stone Environmental, Inc., Montpelier, VT, at page 2-8.   http://www.stone-env.com/water/wwres.html

45  See: http://www.clivusmultrum.com/

46  See: http://www.ecological-engineering.com/carousel.html

47  See: http://www.sun-mar.com

48  Ibid, at page 2-11.

49  Equaris Total Household Water Recycling and Wastewater Treatment Systems. http://www.alascanofmn.com/default.asp?Page=Disinfection

50  Etnier, C.D., et al. (2005) “Micro-Scale Evaluation of Phosphorus Management: Alternative Wastewater Systems Evaluation.” Project No. WU-HT-03-22. Prepared for the National Decentralized Water Resources Capacity Development Project, Washington University, St. Louis, MO, by Stone Environmental, Inc., Montpelier, VT, at page A-45.   http://www.decentralizedwater.org/documents/WU-HT-03-22/WUHT0322.pdf

51  Etnier, C.D., et al. (2005) “Micro-Scale Evaluation of Phosphorus Management: Alternative Wastewater Systems Evaluation. Project No. WU-HT-03-22. Prepared for the National Decentralized Water Resources Capacity Development Project, Washington University, St. Louis, MO, by Stone Environmental, Inc., Montpelier, VT, at page 2-2.   http://www.stone-env.com/water/wwres.php

 

 

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Automatic dishwashers (ADWs) are common in existing homes in Dunes City.  Virtually every new home in Dunes City is expected to have an ADW.  Thus, prohibiting the use of high- phosphate ADD would have an immediate and substantial, beneficial impact on phosphorus levels in on-site wastewater treatment system effluent.  According to the NDWRCDP Research Project Report:

 

“Restrictions on the phosphorus content of dishwashing detergent similar to those for laundry detergent, limiting phosphorus content to 0.5% or less by weight, would result in an average wastewater influent phosphorus reduction of 23% (0.61 g/day) ....”⁵²

 

Low-phosphate ADD performs just as well as high-phosphate ADD but at little additional cost. A recent analysis of policy options for reducing phosphorus loading in Lake Champlain stated the following:

 

“This policy option suggests amending the statutes in Vermont and New York to reduce the P content of all household cleansers to less than 0.5 percent elemental P. ....

 

“Seventh Generation, Inc. has commissioned independent laboratories to test the effectiveness of phosphate-free ADDs in soft and hard water. The results show that phosphate-free ADDs, both powder and gel, performed as well as phosphate ADDs. Seventh Generation uses sodium citrate and sodium carbonate (washing soda) in its ADD powder and a polycarboxylate in its gel.

 

“This analysis estimates that there are 5.5 tablespoons of ADD used per wash [and] that the current price differential between P and non-P ADDs will move towards zero as non- P ADDs become the norm rather than the exception, which affects the cost-effectiveness of this policy option. ….

 

“Currently, phosphate-free ADDs are approximately 15 percent more expensive to consumers than commercial phosphate ADDs.  … Assuming that it is not more expensive to produce phosphate-free ADD products, economic forces should result in no additional cost to consumers from this policy.... If the current price differential is maintained … it will cost $8.65 per year for each household with an ADW ....  Even under this scenario, they found a ban on P in ADDs to be much more cost-effective than many other options. If the ultimate price differential were to become zero, as we assume, the cost- effectiveness of this policy option would be very high.”⁵³

 

In September 2002, Shuster Laboratoriesm a leading independent consumer products testing, quality assurance and R&D firm, compared the performance of several phosphate-free ADDs with the performance of conventional, high-phosphate ADDs, including Procter & Gamble’s Cascade^TM. Shuster Laboratories found that phosphate-free ADDs were just as effective as conventional, high-phosphate ADDs in: 1) removing coffee and tea stains; and 2) preventing filming and spotting.

 

⁵²  _{Ibid.,at page 2-2.}

⁵³  Winsten, J.R. (2004) “Policy Options for Reducing Phosphorus Loading in Lake Champlain.”   http://www.lcbp.org/techreportPDF/47_P_policy_options.pdf

 

 

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Lists, by brand name, of automatic dishwasher detergents and the amount of phosphorus they contain, are readily available.⁵⁴

 

7.2.      Removal of phosphorus via post-septic tank treatment technologies               [ back ]

 

In 2003, the National Decentralized Water Resources Capacity Development Project commissioned a comprehensive survey of technologies and policy options for controlling the release of phoshorous from on-site wastewater treatment systems.  The survey culminated in a report released in June 2005 titled “Micro-Scale Evaluation of Phosphorus Management: Alternative Wastewater Systems Evaluation” (2005 NDWRCDP Research Project Report). More recently, the Massachusetts Alternative Septic System Test Center (MASSTC) evaluated

the performance of several phosphorus removal technologies.  MASSTC presented its findings in a report titled “Evaluation of Methods to Control Phosphorus in Areas Served by Onsite Septic Systems”(June 2006 MASSTC Report).

 

The MASSTC report presents the issues quite clearly. The Executive Summary states: “Phosphorus presents a unique challenge to watershed managers where residences are served by onsite septic systems to the dearth of available treatment technologies and the role that phosphorus plays in the over eutrophication of freshwater ecosystems. …
 

“Three technologies were directly tested for their ability to remove phosphorus. A Waterloo Biofilter ^TM, that demonstrated efficacy in removing nitrogen in previous testing, was modified with a small experimental module of hematite-coated wood chips. The modification exhibited only limited increase in phosphorus removal (~29%) compared with this system without the experimental module (~11%).  Phosphex^TM, a patented upflow filter following a recirculating sand filter and containing basic oxygen furnace slag exhibited > 99% total phosphorus (TP) removal, however the discharge pH was > 11, which precludes discharge to the groundwater under the Massachusetts Department of Environmental Protection regulations.  Attempts to buffer the pH of this

unit were unsuccessful with the exception of a short period following its passage through peat.   PhosRid^TM, a treatment system with a unique configuration that manipulates the valence state of iron to optimize its combination with phosphorus removed > 99% TP following passage through a final sand filter.  This system continues to undergo research and development at MASSTC and has proceeded to the Pilot Approval stage in the Commonwealth of Massachusetts.”

 

It is evident that the phosphate is of first importance and that significant efforts are underway toward developing systems capable of delivering final outflow with total phosphorus less than 1 milligram per liter. While there do not appear to be currently approved systems capable of this performance criterion, it is reasonable to expect that in the next few years they will be available. Some possible contenders are discussed below. 

 

54  Missoula Valley Water Quality District “Automatic Dishwasher Detergents.”   http://www.co.missoula.mt.us/wq/FAQs/LawsRegs/PhosphateBan.htm

 

 

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7.2.1.  Packed-bed filters containing an iron-rich media                                                    [ back ]

 

According to the 2006 MASSTC Report, a packed-bed filter containing iron-rich media called the PhosRID^TM system (Lombardo Associates, Inc.)⁵⁵ appears to a promising system:

 

“PhosRID is a treatment process for phosphorus that proceeds from the work of Robertson (2000) and others based on a process called reductive iron dissolution (RID). Tn this passive process, an iron (Fe[III]) rich porous media is placed in direct contact with unoxidized sewage, such as effluent of a septic tank. …

 

“At first glance, it may appear that the PhosRID strategy for removing phosphorus is much like the standard addition of ferric chloride (FeCl₃) or alum to precipitate the phosphorus. The difference, however is that the iron-rich porous media (containing for instance ferric hydroxide – Fe(OH)₃) is slowly dissolved by the sewage under reducing conditions in the septic tank effluent and is utilized for phosphorus adsorption as it is produced.  Thus the wastewater stream itself ‘triggers’ the release of the phosphorus treatment, reducing the need for accurately dosing amounts of other precipitants such as ferric chloride or alum.  Another difference between simple alum addition and the RID is that the deposition of the iron-phosphorus compounds takes the form of secondary

mineral grains and grain coatings as opposed to a low density flocculant that increases the sludge production (Robertson, 2000).

 

“As configured at MASSTC, the PhosRID system was undergoing continuing development.  …

 

“During the initial three months, the total phosphorus reductions as measured just after the RID media showed significant reductions (Figure 3-12).  However following this initial period, reductions in phosphorus do not appear significant.

 

“This contrasts with the reductions in total phosphorus following the sand filter element of the system (figure 3-13).  During those periods when concurrent samples were taken, total phosphorus levels were generally below our detection limit of 0.5 mg/L.

 

“Data suggest that this technology has potential to remove phosphorus to levels below 0.5 mg/L. However, significant design features must be determined.  The proponent of this technology [Lomardo Associates] has been conducting significant research and developm,ent efforts at MASSTC and continues to do so as of March, 2006.”⁵⁶

 

7.2.2.  Packed-bed filters containing lightweight expandable clay aggregate             [ back ]  

 

_{Examples of lightweight expandable clay aggregate include: Filtralite}^® _{(Optiroc Group AB)}⁵⁷

_{and Utelite}^® _{(Utelite Corporation).}⁵⁸   _{According to the NDWRCDP Research Project Report:}

 

 

    55  For more details, see: http://www.lombardoassociates.com

    57  For more details, see: http://www.filtralite.com/

 

 

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“Lightweight aggregates (LWAs) are a sort of clay ‘popcorn’ with high surface area and are often used in horticulture. Some are specially manufactured to increase their phosphorus-sorption capability. It can be used as a medium in packed-bed filters of various designs. ….  Filtralite is specially manufactured to increase its phosphorus- sorption capability. It can be used as a medium in packed-bed filters of various designs. One type is composed of 62% SiO₂, 18% Al₂O₃, 7% FeO₃, and less than 5% each of K₂O, MgO, CaO, and Na₂O. …

 

“For 12 constructed wetland systems using LWAs, average removal is 79%-98% (Jenssen et al. 2004). Over time, the manufacturer has changed the ‘recipe’ to increase the phosphorus-removal capabilities. Removal percentage is over 95% in all 10 facilities that use blackwater, and they are built from 1991 to 2000. Effluent phosphorus concentrations range from 0.05 to 0.6 mg/L. .... A study in the Florida Keys found that the LWA tested in phase II had the highest phosphorus removal of any method tested, averaging 94% with a mean effluent concentration of 0.53 mg/L (Ayres Associates

2000).

 

_{A special version of Filtralite}^® _{(Filtralite-P) is designed specifically for phosphorus removal.}⁵⁹

Performance data of an onsite wastewater treatment system using Filtralite^® installed in Florida showed treated effluent had phosphorus levels averaging 0.53 mg/L.⁶⁰

 

Filtralite^® has a substantial cross-capacity to remove nitrogen, removing on average 40% of nitrogen in septic tank effluent.⁶¹

 

7.3.      Removal of nitrogen via post-septic tank treatment technologies                      [ back ]

 

The most promising post-septic tank treatment technologies that have been tested for the removal of phosphorus from onsite wastewater treatment systems are two types of trickling filters: 1) the Waterloo Biofilter^TM; and 2) the Nitrex Filter^TM. These technologies were recently evaluated by the Washington State Department of Health.⁶²

 

7.3.1.  The Waterloo Biofilter^TM                                                                                                                [ back ]

 

According to the Washington Department of Health:

 

“[The Waterloo Biofilter^TM] averaged 62% removal of total nitrogen with an average total nitrogen effluent of 14 mg/l over the 13-month testing period. Earlier testing of this 

 

 

58  For more details, see: http://www.utelite.com/

59  Filtralite P.  http://www.filtralite.com/

60  Ayres Associates (2000) “Florida Keys Onsite Wastewater Nutrient Reduction Systems Demonstration Project Phase II Addendum.” http://www.scribd.com/doc/101892657/Wastewater-Management-on-a-Remote-Barrier-Island

61  Ibid.

62  Washington Department of Health (June 2005) “Report to the Puget Sound Action Team: Nitrogen Reducing Technologies for Onsite Wastewater Treatment Systems.”   http://www.psparchives.com/publications/puget_sound/Results_PS_Plan05-071.pdf

 

 

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_{product in a single pass mode demonstrated that it could produce a 20-40% TN}

reduction.”⁶³

 

Unfortunately, the Waterloo Biofilter^TM has only limited cross-capacity to remove phosphorus. According to the MASSTC report:

 

“The modified Waterloo Biofilter removed an average of 29% (median 27%) of total phosphorus (Figure 3-5) over the period tested.  This compares with 11% removal of total phosphorus observed in the standard un-modified Waterloo Biofilter in 1999-2001.

While the modification demonstrated some success, the effluent mean concentration of

4.2 mg/L total phosphorus still exceeds levels generally considered necessary to prevent undesirable environmental consequences.”⁶⁴

 

7.3.2.  The Nitrex Filter^TM                                                                                                          [ back ]

 

According to the Washington Department of Health:

 

“The Nitrex™ is a proprietary trickling biofilter developed at the University of Waterloo in Ontario, Canada. Nitrex™ is designed for denitrification and requires a nitrification process prior to the unit. The nitrification unit can be either a public domain process like a lined sand filter or there are a variety of proprietary products that would serve the same purpose. The unit is filled with a proprietary wood byproduct mixture that promotes nitrogen removal. Wastewater containing nitrate, such as nitrified wastewater is applied to the surface of the Nitrex filter. As the wastewater moves through the organic medium, microbial reduction of the nitrate nitrogen (denitrification) occurs. The bed must remain submerged for this to occur due to the anaerobic nature of this reaction. Typically the units are singlepass and do not require pumping.

 

“Results of testing have been encouraging, with reductions to levels of 2 mg/l reported (Rich, 2003). Unpublished testing data from the Massachusetts Septic System Testing Center (MASSTC) indicate slightly higher results (average of 5.4 mg/l; median of 4.2 mg/l) but still very good results (Heufelder, personal communication 2005).”

 

Unfortunately, the Nitrex Filter^TM has no significant cross-capacity to remove phosphorus. Evaluation of the Nitrex Filter^TM at installations in Oregon, Montana, Massachusetts and Rhode Island showed no significant removal of phosphorus.⁶⁵

 

7.4.      Using post-septic tank treatment technologies in Dunes City                           [ back ]

 

Although the post-septic tank treatment technologies have the best performance in terms of removing phosphorus and nitrogen, respectively, these technologies are still developmental in

 

 

63  Ibid., at page A-45.

64  Massachusetts Septic System Testing Center (June 2006) “Evaluation of Methods to Control Phosphorus in Areas Served by Onsite Septic Systems.”

65  Lombardo Associates (October 2005) “Supporting Information on NitrexTM Nitrogen Removal Treatment System.”

 

 

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