Use Them Now, and Help Us Make Them Standards.
TVNI has completed a full review and revision of Module C of the Guides and Standards suite — the module that covers wastewater, effluent and pollution control. The module now runs to ten entries, and every one has been reviewed. The former Coffee Effluent and Oil Palm standards have been consolidated into a single plantation guide; the Tertiary Treatment and Flower Effluent standards have each been reissued at guide level; a new plain-language companion has been added for the people who actually operate the systems; the Landfill standard has been revised and reissued; and a Floating Islands guide has joined the module. This post introduces the refreshed module, explains the status each document now carries, sets out how a document at guide level is still of real use to a designer and in a contract, and asks for the one thing that will move these guides up to full standards: field data.
The three tiers — guide, standard, specification
A word first on what the labels mean, because they matter more here than almost anywhere else in the suite. Every entry in the package is one of three things. A GUIDE is our best estimate drawn from field practice and the measured record — sound enough to design and build from with judgment, but not yet backed by evidence strong enough to carry a standard’s implied warranty. A Design Standard (DS) is for applications that can carry strict design parameters based on measured and demonstrated results; an engineer can size from it and a contractor can be held to it on an acceptance test. A specification (SPEC) is the contract-and-bidding document that sits under a DS, with the numeric fields a client fills in for a particular site. The designation is a statement about the strength of the evidence, not about the quality of the document. A guide can be written more carefully than a standard; what it lacks is not care but data.
What is now in Module C
With that in mind, here is what the module contains — ten entries, keyed to their codes on the suite page.
Domestic and institutional wastewater. The anchor is the Tertiary Treatment of Effluent guide (C3), for polishing residential and institutional effluent to a compliance standard and removing residual solids. Its new plain-language companion, the Effluent Bed guide (C4), is written not for engineers but for the householder, institution or field technician who owns a bed and has to keep it working — how to size it, the all-important first year, the routine jobs, and what to do when something goes wrong. Around them sit three further documents for the harder domestic cases: the Residential Plot Drainage guide (C7), for greywater, roof and yard runoff and septic-tank leakage mixed together on a single plot; Vetiver Around Pit Latrines (C2); and Vetiver in Open Drains Carrying Untreated Sewage (C8), for the rural and peri-urban communities where conventional treatment is simply out of reach.
Urban stormwater. The Rain Garden module (C6) is a full Design Standard, with its specification sheet, for stormwater management on urban and peri-urban plots.
Agro-industrial effluent. Here the change is largest. The former Coffee Effluent and Oil Palm standards — neither of which carried the measured evidence a standard implies — have been replaced by a single Plantation Effluent guide (C1), covering coffee wet processing and palm oil mill effluent together, with a clear statement of evidence status for the other plantation crops. The Flower Effluent guide (C9), covering the export cut-flower industry of Kenya, Ethiopia, Colombia, Ecuador and Costa Rica, supersedes the earlier flower standard and addresses nitrogen, phosphorus, pesticide, suspended-solids and organic load discharged to adjacent surface waters.
High-strength and open-water applications. Two further Design Standards round out the module: Landfill Leachate (C5), revised this month, covering leachate phyto-utilization together with slope, cover and seep control, and carrying its own specification sheet; and Floating Islands (C10), for treating open water bodies. That two of the ten entries — rain gardens and landfill — are already full standards with spec sheets — is a useful illustration of where the rest of the module is meant to get to.
The four documents we have rewritten
Four of the ten entries were rewritten from the ground up in this pass — the plantation guide (C1), tertiary treatment (C3) and its effluent-bed companion (C4), and flower effluent (C9). They share a method, and it is worth describing because it is what makes them trustworthy. Every numerical value in them carries an evidence tag: measured, demonstrated, analogue, or inferred. A reader can see at a glance whether a figure rests on a monitored installation or on reasoning from mechanism, and design with the appropriate margin. Where we do not yet have an answer, the open question is written down in an annex, with an address to send the data that would close it.
That method forces some uncomfortable admissions, and they are in the documents rather than buried in them. In floriculture, a nitrate-removal figure we had previously published — 86 percent — turned out to have come from carbon-rich tannery effluent; flower-farm drainage is the opposite, high in nitrate and low in carbon, which is exactly the condition in which biological nitrogen removal stalls, and a field installation on such effluent removed closer to a tenth of that. The plantation guide records where vetiver performed only on a par with a local sedge, and a study in which it fared worst of three species on raw palm oil mill effluent. None of this is what a promotional brochure would print. It is in the guides because a designer is better served by knowing where the evidence is thin than by a uniform assurance that hides it.
Why a guide still earns its place in design and contracting
Which raises the obvious question: if most of these are “only” guides, what use are they to someone who has to design a system or write a contract? A great deal, as it happens.
Every one of them does the work a designer actually needs done before sizing anything. It states what to measure in the effluent and on the site before you begin — the plantation and tertiary guides both open with a characterization requirement, because an uncharacterized stream cannot be designed for. It sets out the configurations and the design inputs, the decision gates (containment versus treatment to a consent standard is the first fork, and it changes everything downstream), the loading rates with their evidence class and margin, the failure modes, and the acceptance tests. A designer working from one of these guides knows what to build, what to expect, and — just as important — exactly where the residual risk sits. That is more than many a confident “standard” elsewhere actually delivers.
For contracting the value is just as concrete. The tertiary guide carries acceptance tests and requires a defined, lawful outlet; a contract can cite the guide together with the companion plant-quality and nursery standards, and hold a contractor to planting material of a stated grade, a defined establishment and maintenance regime, and a measurable result on handover. The next step in the package — a specification sheet behind each module, setting out problem definition, performance objectives, design criteria, materials, installation sequence, operation and maintenance, and monitoring indicators, with the numeric fields left open for the site — is what turns a module into something a client can drop into a proposal and a contractor can bid against. That is the step that makes the package commercially usable, and it is already in place for the standards in the module. The honesty is itself a commercial asset: a lender, an insurer or a certification body can see precisely what rests on measured data and what does not, which is worth far more to them than a confident claim they have no way to check.
The bottom line — help us turn guides into standards and specs
So the bottom line of this post is a request. These guides are our best assessment as of today, and we encourage their use now — held-back guidance helps no one, and the coffee mill and the flower farm need something sound to work from this season, not in three years’ time. But a guide is meant to become a standard, and a standard is meant to acquire a specification. That progression runs on evidence we do not yet fully have, and most of it can only come from the field.
We are asking practitioners, estates, service companies and researchers to send us data. Monitored installations above all: influent and effluent quality, flows and loading rates, the area planted, the configuration used, and how the system was operated and maintained. Cost records that a real farm or utility can stand behind. And failures — a system that did not perform, described in enough detail to see why, is more useful to us than another success story. A guide earns promotion to a Design Standard when enough monitored installations exist to support the warranty a standard implies; for floriculture we have set that threshold at monitored sites in at least two of the five countries covered, and comparable thresholds apply to the others. Once a module reaches standard, its specification sheet follows — and the practitioners who supplied the evidence will have shaped the standard, and the contract, that result. Contradicting evidence is as welcome as corroborating evidence, and more useful.
A living technology
One caution applies to every document in Module C, and always will. The Vetiver System is a living biological technology. It responds to sunlight, temperature, rainfall, water chemistry and the turn of the seasons, and no two sites are alike. But in our long experience the largest and most variable factor is none of these. It is the design and quality of the application, and the management after the plants are in the ground. A bed sized correctly, planted with good material at the right density, and cut and maintained on schedule will outperform a poorly built one on a better site, every time. No guide or standard can substitute for that care. What these documents can do — and what we have worked hard to make them do — is tell you what you must get right, and show you where the evidence for it stands.
Module C is available now in the Guides and Standards suite at https://vetiver.org/vetiver-grass-technology/design-standards/ Use it, put it to work, and send us what you find — including where we have got it wrong.
— Dick Grimshaw, The Vetiver Network International