[ca-gw] Salt Build Up in the Soil

Tue Nov 3 12:34:34 PST 2009

Soil salination and alkalinity is a complex subject, but one way of looking at it is to flip it around and view it as a lack of soil carbon.  The code coincidentally addresses this well with its emphasis on mulch (the first time I have seen 'mulch' in a code-long overdue!).  

Generally speaking, the nutrients in graywater foster a bloom in soil ecology which, in the presence of a carbon source, increases the biomass in the soil and the overall soil permeability.  The minerals in graywater-sodium, chloride, sulfur-are essential cell salts.  

Sodium in particular has a destructive effect on the soil structure and especially clay soils, mitigated by the presence of calcium and magnesium (this is also a complex subject, but can be roughly characterized by determining the SAR-Sodium Absorption Ratio, the ratio of sodium to calcium and magnesium.  Values above 12-15 can seriously degrade the permeability of a soil, and the ability of plants to uptake water).  

So, bottom line, having a graywater system on good organic soil with a mulch cover will enable the good absorption of annual rainfall and the leaching of excess salts, while good carbon content (mulch, soil humus) and a thriving soil biomass (nutrients in graywater) will mitigate the buildup of salts.  Boron is probably the biggest problem in this scenario if it is used in cleaning and laundry products, and this should be avoided (no 20 Mule Team Borax, with apologies to former pitchman Ronald Reagan).

As a general principal, the redirection of graywater from the conventional sewage treatment plant and discharge to a 'receiving body' (what we used to call rivers and streams, bays and seashores) is a much more effective way of handling soluble constituents that can biodegrade.  Aquatic systems are poorly suited to handle remediation, and ecologically affected in a negative manner very easily, while soil-based systems and bacteria have been shown to be capable of remediating the most toxic chemicals and are extremely capable.  

Diverting graywater to soil systems also retains the phosphorus content on land.  Phosphorus depletion from soil systems is a serious long-term problem, while phosphorus buildup in near-shore ecosystems is a serious long-term problem resulting in nearly permanent red tides and shifts in the phytoplankton ecology that have generally not been favorable along both coasts of the US.

So-Fix Carbon, Retain Phosphorus

For further reading, check the expanding awareness of 'Bio Char' in affecting soil carbon interactions with charcoal, and the commercial Humate products that are available as soil amendments, such as TRI-C HUMATE, available thru S&S Seeds in Carpenteria ( www.ssseeds.com <http://www.ssseeds.com/>  ).

I have designed or installed modern graywater systems that have been in place for over 15 years with diversified landscapes and lawns, with no appreciable problems.  I do have a subsurface drip system in Malibu on straight septic tank effluent, however, that experienced a buildup of boron in the soil that eventually inhibited citrus and apricot trees, and we tracked it down to using a borax laundry product, which was discontinued; but otherwise even straight septic tank effluent has performed well over at least a 20 year period in subsurface drip irrigation systems in jurisdictions where they have been allowed (Hawaii, Malibu, Georgia, etc..

Hope this illuminates!

Best wishes,

Bill

Bill Wilson, Associate

Environmental Engineering & Sustainability

CARLILE * MACY

15 Third Street, Santa Rosa CA 95401

Tel: (707) 542-6451, ext 1551 Cel: (805) 689-7639 Fax: 542-5212

Best Places To Work   |   Northbay 2007-2009

wwilson at carlilemacy.com   |   www.carlilemacy.com <http://www.carlilemacy.com/> 

________________________________

From: ca-standard-bounces at graywater.org [mailto:ca-standard-bounces at graywater.org] On Behalf Of Jon Barsanti
Sent: Monday, November 02, 2009 10:14 AM
To: courtney miller
Cc: ca-standard at graywater.org
Subject: Re: [ca-gw] Salt Build Up in the Soil

There have been a few articles regarding using graywater tolerant landscaping

http://latimesblogs.latimes.com/home_blog/2009/10/the-dry-garden-emily-green-droughttolerant-gardening-lowwater-gardeing.html

http://waterquality.montana.edu/docs/methane/long_term_irrigation_S_Australia.pdf

http://www.grounds-mag.com/mag/grounds_maintenance_reclaimed_water_challenges/

and one which is unrelated to the discussion

USF studies viruses in Reclaimed water http://www.waterandwastewater.com/www_services/news_center/publish/industry_news/Viruses_in_Reclaimed_Water_printer.shtml

Jon Barsanti, Jr.
Development and Infrastructure Planner
Triangle J Council of Governments
PO Box 12276
RTP, NC 27709
919.558.2709 Direct
http://www.tjcog.dst.nc.us/regplan/di.shtml  D&I Partnership
http://www.tjcog.dst.nc.us/regplan/smrtgrow.shtml Smart Growth Committee
http://www.tjcog.dst.nc.us/regplan/core.shtml  CORE

"The significant problems we have cannot be solved at the same level of thinking with which we created them."
Albert Einstein (1879 - 1955), (attributed)

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	----- Original Message ----- 

	From: courtney miller <mailto:courtney at gis.net>  

	To: ca-standard at graywater.org 

	Sent: Thursday, October 29, 2009 9:28 PM

	Subject: [ca-gw] Salt Build Up in the Soil

	HI Everyone,

	Just recently joined the list.

	I just heard from a landscape architect that greywater systems over time have the effect of increasing the salt content of the soil.

	That would make sense - showers and kitchen sinks. Sweat on clothing. 

	Has anyone had a system out there long enough to make that evaluation?

	I imagine that it would take a long time to have this kind of soil degradation.

	What's everyone's take on that?

	Courtney Miller

	>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 

	Courtney Miller, RA, LEED AP

	2401 Ivy Drive/ Suite 100

	Oakland, CA 94606

	Tel: 415 637 8446

	Email: courtney at gis.net

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