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Limpopo Dairies Constructed Wetland Schematic Construction & Operational Management Plan

13 November 2012

www.ncc-group.co.za

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Table of Contents 1. EXECUTIVE SUMMARY ................................................................................................................... 4

2. INTRODUCTION .............................................................................................................................. 6

3. LEGAL & REGULATORY REQUIREMENTS ........................................................................................ 6

4. ASSUMPTIONS AND EXCLUSIONS .................................................................................................. 7

5. SYSTEM ANALYSIS & RECOMMENDATIONS .................................................................................. 7

5.1 Fat Trap – ITEM 1 .................................................................................................................... 8

5.1.1 Current Status ................................................................................................................. 8

5.1.2 Proposed Solution .......................................................................................................... 9

5.1.3 Current Risks ................................................................................................................. 10

5.2 Solids Removal – ITEM 2 ...................................................................................................... 10

5.2.1 Current Status ............................................................................................................... 10

5.2.2 Proposed Solution ........................................................................................................ 11

5.2.3 Current Risks ................................................................................................................. 12

5.3 Conveyance of Effluent to Wetland Treatment – ITEM 3 ................................................... 13

5.3.1 Current Status ............................................................................................................... 13

5.3.2 Proposed Solution ........................................................................................................ 14

5.3.3 Current Risks ................................................................................................................. 15

5.4 Facultative Pond – ITEM 4 .................................................................................................... 15

5.4.1 Proposal ........................................................................................................................ 15

5.5 Pump station – ITEM 5 ......................................................................................................... 16

5.5.1 Proposal ........................................................................................................................ 16

5.6 Vertical Flow Wetland – ITEM 6 ........................................................................................... 16

5.6.1 Proposal ........................................................................................................................ 17

5.7 Horizontal Flow Wetland – ITEM 7 ...................................................................................... 19

5.7.1 Proposal ........................................................................................................................ 19

5.8 Polishing Pond – ITEM 8 ....................................................................................................... 20

5.8.1 Proposal ........................................................................................................................ 20

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5.9 Pipeline to Irrigation – ITEM 9 ............................................................................................. 21

5.9.1 Proposal ........................................................................................................................ 21

6. WETLAND AND PONDS CONSTRUCTION GUIDANCE .................................................................. 22

6.1 Planning/Pre-construction ................................................................................................... 22

6.2 Site Preparation .................................................................................................................... 22

6.3 Vegetation & Landscaping ................................................................................................... 23

6.4 Planting ................................................................................................................................. 23

7. WETLAND AND PONDS OPERATING GUIDANCE ......................................................................... 23

7.1 Construction to commissioning - What to Check for: ......................................................... 23

7.2 Water level management .................................................................................................... 24

7.3 Wetland maturation ............................................................................................................. 24

7.3.1 First six months ............................................................................................................ 24

7.3.2 After the first year of operation .................................................................................. 25

8. SUMMARY OF ACTION AND OBJECTIVES .................................................................................... 25

9. FURTHER INVESTMENT CAPITALISATION .................................................................................... 26

9.1 Biogas .................................................................................................................................... 26

9.2 Compost ................................................................................................................................ 26

9.3 River Water Treatment ........................................................................................................ 26

9.4 Proposed operations expansion .......................................................................................... 27

10. HOW CAN NCC HELP YOU ........................................................................................................ 27

10.1 Legal Services ........................................................................................................................ 27

10.2 Project planning ....................................................................................................................... 27

10.3 Project management ................................................................................................................ 27

10.4 Monitoring and maintenance .................................................................................................. 27

11. DISCLAIMER .............................................................................................................................. 28

12. LIST OF APPENDICES: ................................................................................................................ 28

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PROJECT: LIMPOPO DAIRIES CONSTRUCTED WETLAND PROJECT

LOCATION: LOUIS TRICHARDT, LIMPOPO

ATTENTION: WILLIE DU PREEZ

DATE: 13 NOVEMBER 2012

1. EXECUTIVE SUMMARY

With South Africa being a water constrained country, many rural farming communities and

businesses face serious challenges regarding water supply of the required quality to be used for

operational activities.

Additionally, waste water management is another key concern in South Africa’s mix of

environmental challenges. With a rapidly increasing rate of degraded natural water ecosystems, it is

critical that all sectors play their part in mitigating, and where possible preventing, continued

effluent discharge into our heavily exploited and greatly degraded ecosystems. The agricultural

industry has historically been seen a major culprit in contributing to not only excessive water reserve

use, but also being responsible for introducing pollutants into natural systems that further diminish

the water reserve and associated life supporting ecosystem functions.

It has been recognised by numerous parties at various levels that historical business-as-usual

practices are becoming less viable. To the industry’s credit, the commercial farming sector is

realising that this is most certainly the case with regard to natural resource management. In

particular, water use and the release of pollutants into our natural water systems are agenda

priorities. There are a number of pioneer farming organisations taking the lead in adopting a new

sustainability focussed and environmentally responsible business approach. NCC is proud to be

associated with industry leaders, such as Limpopo Dairies, who are actively looking for ways to

improve their operational performance. This is not only responsible undertaking, but also a risk

minimising, cost effective approach to sustainable business practice and an approach that positions

them strategically in the market as an environmentally cognisant corporate citizen.

NCC was approached by Limpopo Dairies to provide guidance on their waste water management

through identifying the opportunities in implementing a constructed wetland system that would

treat waste water produced by their operational activities efficiently and effectively. Various waste

streams were identified. These included effluent generated directly from dairy operations, product

processing activities, as well as domestic sewerage.

NCC conducted a site visit to inspect the existing water treatment infrastructure and identify

opportunities for Limpopo Dairies to improve the quality of the effluent generated from their

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operations, resulting in less localised pollution of their land and surrounding water resources.

Limpopo Dairies management requested that NCC investigate the necessary interventions required

to successfully achieve their waste water treatment objectives through the implementation of a

constructed wetland. Through assessing the current infrastructures and conditions at Limpopo

Dairies, NCC has compiled a proposed high level schematics construction and operational

management plan detailing required structural and process requirements, as well as operational

management considerations. NCC’s proposed system is based on maximising the following basic

principles:

Efficiency;

effectiveness; and

feasibility.

The proposed system will allow for waste water to be effectively treated to a quality that exceeds all

regulatory requirements as stipulated in the agricultural requirements for crop irrigation. All

treatment is conducted in an enclosed environment, thus ensuring that no fugitive pollution is

experienced outside of the treatment infrastructure. All proposed developments will significantly

reduce the legal risks with regard to waste water storage, release, and treatment.1 The suggested

designs should also reduce the operation’s relative demand on primary water abstraction from

surrounding water reserves.

NCC's proposed design also allows for efficient biomass harvesting as a by-product which can be

used as fuel for biodigesters which, through the harvesting of methane, could be used to generate

heat and electricity for the operation. The systematic interaction between resource and waste

management systems will result in long term cost savings and operational efficiencies, as well as

reducing adverse environmental impacts such as water and soil contamination and increased

Greenhouse Gas emissions

NCC proposes a system that incorporates a series of structural, mechanical, chemical and biological

processes that will, if used in the suggested a critical sequence and according to the required

specifications, deliver on the outcomes as suggested above.

In broad terms, the system uses robust filtration systems to reduce the solids content of the effluent

through the incorporation and upgrading of the existing solids and fat traps. The effluent is then

transported to the primary facultative pond, where larger suspended solids that were too fine to be

trapped by the filtration stations, settle to the pond floor where they are consumed by microbial

action. The effluent then flows into sub surface flow settlement ponds where horizontal and vertical

flow action is designed to treat the waste water through volatilisation, filtration, UV exposure,

oxygenation and further microbial action. Once through the sub surface flow ponds, the treated

1 Although this system is designed to comply with legislative requirements in terms of its operational

functions, it is absolutely critical that all approvals, licensing and permits and permissions are granted by the relevant local authorities prior to construction and commissioning.

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water is then transported to the polishing ponds where final UV breakdown and microbial action,

facilitated by the implementation of floating reed beds, further reduce remaining pollutants to a

quality suitable for agricultural irrigation.

2. INTRODUCTION

This report has been compiled to address the waste water treatment problems being experienced by

the client, Limpopo Dairies.

The client expressed a desire to explore the feasibility of a Constructed Wetland System (CWS), as a

means of handling, treating and recycling waste water generated by their operations, ultimately

providing an alternative water resource of acceptable quality and standard for the farm’s irrigation

requirements.

A site visit was conducted at the end of June 2012 to assess Limpopo Dairies’ current waste water

management infrastructure. In addition to the site visit, NCC requested that soil and water samples

be taken and tested for key pollution indicators at strategic points in the existing system. The

findings of the site visit, test results and best practice principles were incorporated in the assessment

of the current conditions in order to determine the best course of action for Limpopo Dairies to

achieve their desired water management outcomes.

3. LEGAL & REGULATORY REQUIREMENTS

It is important to familiarise oneself with the legal requirements at the outset of this project, as this

aspect of the planned proposal warrants careful consideration. Certain requirements and

responsibilities are placed on the client, which must be properly understood and adhered to from

the outset.

With reference to Addendum IV, the following legislation has been identified and must be adhered

to should the decision be made to go ahead with the implementation and commissioning of the

proposed CWS.

It is critical that should Limpopo Dairies decide to pursue the implementation and operation of a

constructed wetland, consultation with a legal practitioner must be sought to ensure that all

legislative and regulatory requirements are complied with.

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4. ASSUMPTIONS AND EXCLUSIONS

The following assumptions and exclusions form part of this report and are listed as follows:

Water test results received did not provide sufficient comfort on NCC’s part to place full reliance on

the data that was provided. In light of this situation, where NCC felt that readings were not reliable,

reliance was placed on industry standard readings as benchmark guidelines for the design of the

CWS. This approach was taken to ensure that all system components would handle the waste water

sufficiently enough to mitigate and / or prevent risks associated with pollution resulting from the

ingress or discharge, be it intentional or unintentional, of water within the proposed CWS system.

Soil Tests were performed to determine the extent of contamination of the surrounding soils on the

perimeter of the existing settling dams as well as the waste water trench connecting the solid and

fat traps with the settling ponds. It was decided it would not be feasible to use the existing

infrastructure as remediative and reconstructive efforts would be too costly.

The proposed schematics were designed according to the volume per day estimations as provided by

Limpopo Dairies. A figure of 250 000l per day was provided to NCC, and it was agreed that this figure

was to be used to guide the proposed CWS design.

5. SYSTEM ANALYSIS & RECOMMENDATIONS

What follows is a component-by-component analysis of the entire waste water system, from the

point source effluent discharges down to the treatment area.

All key components have been numbered in this report and corresponding numbers can be found in

the plan layouts attached in addendums II and III.

Each section describes the current state of the existing items and the suggested proposal to remedy

or improve the functionality of each system component. New or proposed system components will

be introduced and described. Each section will include a technical and environmental aspect where

relevant to aid understanding.

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5.1 Fat Trap – ITEM 1

This device, known as a FOG (Fats, Oils & Grease) Trap, is responsible for removing all FOG particles

from the waste water stream, which prevents clogging and fouling of pipes down-stream.

5.1.1 Current Status

5.1.1.1 Technical

The current FOG trap shows signs of serious deterioration. There is clear evidence that maintenance

is not being performed regularly, which has resulted in a large layer of fat build up on top, roughly

500mm thick.

Above: Layer of solidified fat on top of current FOG trap.

The danger with leaving this full of FOG is that the water eventually breaks the FOG particles down

through a process called hydrolysis. This results in certain particles becoming denser and thus able

to pass through the grease trap.

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Above: Dividing baffle wall and FOG trap outlet

The dividing baffle wall and outlet are also not functioning correctly. The presence of excessive FOG

in the second chamber indicates that separation is not occurring effectively and that the outlet is not

correctly designed to deal with the effluent.

This is most undesirable for the proposed wetland scheme downstream as the presence of FOG in

the effluent will block up the wetland and drastically reduce its effectiveness.

5.1.2 Proposed Solution

5.1.2.1 Technical

It is proposed that refurbishment of the existing FOG trap takes place. This will include draining the

structure, lining it and checking the design of the internal baffles and outlet heights.

Due to the presence of FOG in the second chamber, a re-design of the internal workings of the unit is

proposed, which will include the removal of the dividing wall and a re-design of the outlet port.

It is further recommended that a series of lids be placed on the unit, to prevent excessive dust and

sand from blowing into the structure which will increase the required maintenance intervals.

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5.1.3 Current Risks

There are several risks associated with leaving this unit in its current state. These include, but are not

limited to:

Blockage and fouling of downstream pipelines

Costly maintenance and repair

Fouling and deterioration of the proposed wetland system

5.2 Solids Removal – ITEM 2

This unit is located downstream of the FOG trap and is responsible for removing most of the solid

material found in the waste water stream. Typical solids include manure, feed, bedding and sand.

5.2.1 Current Status

5.2.1.1 Technical

The current device consists of a traditional ramped relaxation pond, which allows the solid material

to naturally settle out of the water over time. This traditional method is very effective, but like most

structures of this nature, requires maintenance.

Above: Ramped relaxation pond

While the inlet and structure look fairly sound and in good condition, the outlet water indicates poor

system performance.

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Above: Relaxation pond outlet

The presence of excessive amounts of manure past the outlet reveals that the timber pole structure

is not effectively retaining the manure particles. These manure particles dissolve, break up and

become fine enough to pass through the timber “filter”.

5.2.1.2 Environmental

It is imperative that as much of the organic matter as possible be removed to reduce the strain on

the wetland system. Failure to do so will result in an elevated Biological Oxygen Demand (BOD) level

which in turn requires a larger wetland system as well as an increased retention time.

5.2.2 Proposed Solution

5.2.2.1 Technical

Given the clients desire to potentially explore biogas technologies, it is imperative that solids

removal be done effectively and quickly, so that raw material is constantly available for the biogas

unit.

The installation of an inclined screen de-watering filter is proposed, which consists of a large inclined

screen, over which you run the waste water stream.

Water passes through small holes in the screen, into a pipe and continues on for further treatment,

while the solid particles are kept behind on the screen and pushed down to an area where they are

removed and added to the biogas feedstock.

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Above: The type of device being proposed. An exact model and manufacturer will be selected

once detail design of the system has been performed.

5.2.2.2 Environmental

In a similar vein to the presence of FOG in a CWS, the performance of chemical, mechanical and

biological processes within the system will be inversely proportional to the amount of solid material

present in the waste water entering the CWS. Removal of solids in the initial stages has considerable

benefits with regards to the sizing and structural interventions required to treat the effluent. The

lower the levels of suspended solids in the system, the smaller the size of the system, and therefore

the costs of implementation are lowered.

5.2.3 Current Risks

There are several risks associated with leaving this unit in its current state. These include, but are not

limited to:

Oversizing of wetland to deal with high BOD levels.

Blockages of pipes

Clogging and blocking of wetland system

Accumulation of pollutants

Release of pollutants into surrounding ecosystems

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5.3 Conveyance of Effluent to Wetland Treatment – ITEM 3

Currently this consists of a machine dug furrow in the soil and runs from the existing solids removal

structure to the current treatment ponds.

5.3.1 Current Status

5.3.1.1 Technical

The current furrow has been machine dug with inconsistent depth and width. There are clear signs

of erosion along the entire length of the furrow.

Above: The general state of the furrow and the manure present confirms the lack of proper

separation.

The continued erosion of this furrow will diminish its ability to maintain proper flow velocity. The net

result is that in order for this furrow to function adequately, regular re-digging, filling and re-shaping

will have to be performed. These activities are time consuming and costly as the length of the furrow

is approximately 400m long.

5.3.1.2 Environmental

The current use of the furrow as a conduit for effluent to reach the settling ponds has resulted in

localised contamination of the soil along the length of the structure. Soil integrity has been

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compromised further by erosive action on the walls of the furrow. This has two implications. Firstly,

increased sediment load enters the effluent creating the potential for blockages and infrastructural

damage. Secondly, it raises the suspended solids content of the effluent.

The present system is resulting in gross pollution of the water table and ultimately the aquifer. This

is due to seepage from the furrow as well as extensive infiltration during rainfall episodes.

5.3.2 Proposed Solution

5.3.2.1 Technical

A new underground pipeline is proposed that will run from the solids removal area down to the

newly constructed wetland. This pipeline will have a suitable fall to ensure a self-cleaning velocity of

flow.

Above: Section of broken culvert piping

The picture above illustrates this point clearly. The surrounding furrow is laden with manure and

settled solids, while the small segment of pipe is clean internally.

This is due to a smooth pipe surface and increased velocity, arising from a smaller cross sectional

area of flow. Therefore, the commissioning of a pipeline will provide a far more efficient means to

transport the effluent to the constructed wetlands.

Manholes and access points for maintenance and cleaning, or to address any unforeseen issues, will

be placed at regular intervals along the pipeline.

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5.3.2.2 Environmental

The benefit of a pipeline as opposed to an open furrow prevents localised erosion along the length

of the pipeline, thus preserving the integrity of the surrounding soil and reducing effluent sediment

load. Additionally, the localised environment will not be exposed to pollutants contained in the

effluent. Transporting the influent in a pipeline will negate the infiltration of pollutants into the soil

and ultimately the aquifer or underground water table.

5.3.3 Current Risks

There are several risks associated with leaving this furrow in its current state. These include, but are

not limited to:

Continuous maintenance required of the furrow

Furrow wall erosion

Raised suspended solids levels in effluent resulting in damage to infrastructure and

compromised water quality

Localised contamination of the soil adjacent to the furrow

Pollution of otherwise accessible potable water. This is not limited to the local setting but

also applies on a regional level, reducing the usability of water resources and furthermore

negatively impacting on biodiversity through changing natural habitats such as rivers.

5.4 Facultative Pond – ITEM 4

This structure represents the start of the new CWS. The facultative pond receives all the effluent

waste streams from where it is pumped to the vertical and horizontal flow wetlands.

5.4.1 Proposal

5.4.1.1 Technical

A facultative pond is currently envisaged for the CWS. These ponds are widely used as a means for

blending the waste streams into a more consistent solution for the wetland.

It provides a buffer for the CWS should there be severe rainstorms and sudden inflow of rainwater. It

also allows the user to select which wetland train is to be flooded. This will be elaborated on in the

next section.

Due to the fall of the land, current indications suggest that there will not be enough natural fall to

flood the vertical flow wetland section naturally, which means a holding pond and pump

arrangement is required for this.

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Based on accepted modelling methods, it has been determined that the pond should contain at least

10 days’ worth of effluent discharge and have enough freeboard to accept rainfall and runoff water

that could enter the system.

The extent and scale of this pond has been indicated on the plan layout, found in addendum X, and

shall be constructed to an engineered design, with engineered lining.

5.4.1.2 Environmental

A population of anaerobic organisms will colonize accumulated sludge on the bottom of the

facultative pond. The surface area of the pond is large enough to provide an atmospheric oxygen

transfer rate adequate to prevent anaerobic conditions on the pond surface. The intermediate

depths of the pond support facultative micro-organisms capable of oxidizing both the dissolved and

suspended organics from the original wastewater and the products of anaerobic catabolism on the

bottom of the pond. Facultative ponds are capable of reducing both the BOD and total suspended

solids by up to 65%.

5.5 Pump station – ITEM 5

The pump station will be used to provide pressurised water to the irrigation system of the vertical

flow wetland.

5.5.1 Proposal

5.5.1.1 Technical

The pump station will be situated above ground and be of a self-priming type, in a covered

enclosure.

The set will be made up of 2 pumps in a duty/standby arrangement to provide redundancy.

The pump set will draw water out of the facultative pond and pass this through a series of pipes and

valves, which will be automated. The user will be able to select which wetland ‘train’ to irrigate.

Pumps will be sized to match the total inflow rate of water so that flooding can be averted.

5.6 Vertical Flow Wetland – ITEM 6

Following the facultative pond and pumps set are two ‘trains’ or wetlands, each comprising of a full

wetland system, as indicated on the plan layout in addendum X.

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5.6.1 Proposal

5.6.1.1 Technical

BOD5 removal is a function of temperature and residence time in the system.

A widely used first order kinetic model is:

[Ce/Co = exp(-KTt)]

Where:

Ce = effluent BOD5 , mg/L

Co = influent BOD5 , mg/L

KT = temp dependant first-order reaction rate constant, d-1

t = hydraulic residence time, d

Using this equation, along with other associated formulas, sizing and predictions relating to the

wetland’s effectiveness are able to be determined.

The water is irrigated over the surface of this wetland section and allowed to drain down through

the various layers, to connection pipes at the bottom of the cell.

Since the bottom of the wetland is sloped, to achieve a required gravitational flow of water, all

water will eventually run down and across to the connection pipes, and onto the next treatment

section, as can be seen in the plan layout found in addendum I and II.

The vertical flow wetland shall be constructed according to an engineered design, with engineered

lining.

5.6.1.2 Environmental

5.6.1.2.1 Substrate

Although aggregate is often recommended as a substrate for Vertical Flow Wetlands, a combination

of both soil and aggregate is preferred. The reason for this is that soil is required as both a growing

medium as well as for essential processes. Besides the microbial and fungal decomposition of

organic matter and pollutants in the rooted soil or substrate matrix, chemical and physical

precipitation, adsorption and filter processes occur due to the presence soil constituents like clay

minerals and humus particles. This is very important for phosphate and ammonia binding.

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Topsoil excavated from the site will be used as part of the substrate layer. The medium to fine

particle distribution of the soil at site will need to be modified to improve the treatment capabilities

of the reed bed. Whilst permeability of the sand is high, the fine nature will cause problems with

free flow of water. To enable more uniform flow characteristics, small particle size (5-7mm) gravel

should be mixed with the sand. Organic matter within the soil on the site is low, and should be

improved by the addition of freshly cut lawn grass. This will not only give additional organic content

to the soil, promoting bacterial propagation, but will also add a nitrogen source to allow

development of the reeds after planting. Soil at site should therefore be mixed with 5-7mm gravel

and organic matter, to form the growing medium.

The soil should be evenly mixed to a proportion:

Site soil (sand) 70 %

Aggregate (5-7mm) gravel 15 %

Freshly cut lawn grass 15 %

Substrate will be laid in three separate layers, ensuring that at least 600mm free-board be left above

the substrate to allow for accumulation of organic matter originating from the reeds.

Outlet piping on the base of the bed will be immersed in 350mm depth of 20-50mm gravel

The large gravel will be covered by 150mm of 5-7mm aggregate

The medium level is then raised to within 600mm of the rim with the mixed soil.

5.6.1.2.2 Planting

Fluitjiesriet Phragmites australis or P. mauritanicus will be planted to populate the reed bed in the

wetland cells.

Planting materials may be obtained locally. If roadside ditch or other natural depression material is

used, there is a risk of incorporating unwanted weeds into the cells.

Plants should be properly stored prior to planting. This involves proper moisture and temperature

conditions, proper handling and minimal delay time.

Planting stock should not be dug more than two days before planting and should be stored and

transported in a cool, dark, humid environment.

If mature emergent plants are dug for planting, the stalks should be cut off to 20-30cm until the

roots have re-developed a secure attachment in the substrate. This is due to the fact that tall plants

are susceptible to wind-throw.

The substrate can be left prepared for some time prior to planting and/or seeding, however it should

be protected from erosion and treated for weeds.

Ensure that the wetland substrate is level.

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Optimal planting conditions for cut materials are created by shallow flooding followed by

dewatering. Do not allow to dry completely. Conditions should be soft, moist soil.

Small clumps (diameter 10-15cm) must be planted at a density of four plants per m2 to ensure rapid

colonisation of the wetland cell

Planting must be done in rows and must run perpendicular to the direction of the flow. This is to

improve coverage and reduce channelling. Although it may be easier to operate equipment up and

down the long axis of a cell, this is not recommended.

After planting, the cells should be flooded with 1 - 2.5 cm of water. Ensure that water depths do not

overtop cut stalks or the new plantings may die.

As new growth begins, water levels may be slowly raised but should not overtop the new growth.

Emergent plants are not as susceptible to drowning after first growing season or in waters with

relatively high dissolved oxygen content.

Inappropriate water levels can inhibit establishment and growth of desirable wetlands plants,

however unsuitable levels can be used to control prolific growth and spread of weedy, terrestrial

species. Flooding may retard invasion by terrestrial opportunists and deeper flooding may retard

undesired colonization of additional areas by planted wetland species.

5.7 Horizontal Flow Wetland – ITEM 7

This wetland section facilitates the flow of water moving underground and horizontally towards the

polishing pond.

5.7.1 Proposal

5.7.1.1 Technical

Using the first order kinetic model formula this section of the wetland system has been sized to

reduce the BOD5 of the water to under 100mg/L.

Current survey levels suggest that flow should be able to naturally gravitate to the horizontal flow

section without the need for pumps.

Over the length of the two wetland sections, the plans suggest a 1.5m natural drop in elevation,

which should be sufficient.

This pond has relatively few technical aspects which means little maintenance is required.

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Positioned at the end of the wetland section are connection pipes that convey the water to the

lower lying polishing pond. These will be installed near the bottom and discharge into the polishing

pond near the surface of the water.

The Horizontal Flow Wetland shall be constructed according to an engineered design, with

engineered lining.

5.7.1.2 Environmental

A fine aggregate (2-5mm) is the preferred substrate for Horizontal Flow Wetlands. This is due to the

reeds and the substrate not performing as important a function as in the aerobic Vertical Flow

Wetland.

As with the Vertical Flow Wetland, engineered lining is recommended. The use of engineered lining

is crucial for three major reasons. Firstly, the impermeable structure ensures that no contamination

of the surrounding soil occurs. Secondly, all water is contained within the system, thus maximising

water yield once treated. Finally the lining ensures that the structural integrity of the ponds and

wetlands is maintained.

Planting

The Horizontal Flow Wetland is planted in the same manner as the Vertical Flow Wetland.

5.8 Polishing Pond – ITEM 8

The polishing pond is the last step of treatment process and receives water from both wetland

‘trains’.

5.8.1 Proposal

5.8.1.1 Technical

There are no determining criteria for sizing a polishing pond.

The proposed size is based on a retention time of 10 days, so that the facultative pond can

completely drain and that a full batch of water can pass through the system and remain contained.

This becomes useful when invasive maintenance is required on the system. Instead of purging the

contents of the system onto the adjacent lands, one can allow the processing to continue, while

works are performed on the system.

At the end of the pond a sump outlet with filter screen and pump is proposed. This will be the start

of the connecting pipeline to the irrigation system.

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5.8.1.2 Environmental

It is recommended that floating reed islands be installed in the polishing pond.

Floating reed islands comprise of a floating raft structure where the plants are initially rooted in a

matrix or soil media and eventually become self-supported on intertwined mats of their own

buoyant roots and rhizomes as well as accumulated plant litter and organic matter.

Because they float on the water surface, floating reed islands are little-affected by fluctuations in

water levels that may submerse and adversely stress bottom-rooted plants.

Water receives treatment as it passes through the root mass that develops beneath the floating

wetland. Fine particles may potentially become entrapped within this hanging root mat and

associated biofilms. They are excellent at removing nutrients and heavy metals and furthermore

provide a degree of shading thereby reducing the possibility of algae in the water column.

It is recommended that at least 10% of the ponds surface area be covered by floating reed islands.

The same reeds as used in the constructed wetlands i.e Fluitjiesriet Phragmites australis and P.

mauritanicus can be used on the floating islands.

5.9 Pipeline to Irrigation – ITEM 9

This pipeline will be used to convey the treated water down to the nearest irrigation pump station

from where it will be distributed.

5.9.1 Proposal

5.9.1.1 Technical

This will be a relatively small diameter pipeline made from CL9 uPVC high pressure pipe and fittings

and will be pumped down from the sump in the polishing pond to the nearest reservoir.

The survey plan suggests a fall of about 1m, so adequate fall is available for a healthy flow rate and

this will reduce the size of pump required.

The pipeline will be laid and backfilled to engineered specifications.

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6. WETLAND AND PONDS CONSTRUCTION GUIDANCE

6.1 Planning/Pre-construction

As a minimum, the plans and specifications should outline the following:

Clearing and grubbing limits of demarcated areas

Location of benchmark

Final grades

Existing and proposed utilities

Borrow areas

Types of structures to be constructed

Types of equipment to be used (e.g. pumps, irrigation etc.)

Dimensions of all structures

Berm and structure material identification

Floor and wall permeability

Environmental and structural impact control structures

Undisturbed areas identification

Erosion control plan development

Seeding, sodding and planting requirements identified and documented

The specifications should also clearly outline the construction and planting period and any

restrictions on either site access, completion date (and penalty if any), bonding requirements,

testing methods (permeability), plant survival determination (to determine if replanting is

necessary), payment method, start-up and acceptance procedures.

6.2 Site Preparation

Prior to constructing the individual components of the wetland system some site preparation work is

required. The following steps should be followed:

Construction should happen in the dry season

Identify and document the survey benchmark

Establish site boundaries and identify areas to be protected

Clear and grub works area

Remove and stockpile topsoil for later use. Avoid mixing topsoil with underlying material.

Protect topsoil from contamination. If existing wetlands soil is removed for later use, it

should be stored underwater to avoid oxidizing and releasing bound metals or other

substances

Remove all permeable soil materials, organic matter, rocks, trash or debris

Peg out the excavation and fill areas and locate the position of structures. This work should

be done with precision and it is therefore recommended that survey equipment be used.

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6.3 Vegetation & Landscaping

Phragmites will be planted to vegetate the wetland

Ensure that at least 30 cm of topsoil (or wetland substrate) is placed, uncompacted, on the

cell floor

Ensure that the wetland substrate is level

The substrate can be left prepared for some time prior to planting and/or seeding, however

it should be protected from erosion and treated for weeds

Make sure that the wetland substrate is moist (not flooded) just prior to planting or seeding

6.4 Planting

Optimal planting conditions for cut materials are created by shallow flooding followed by

dewatering. Do not allow to dry completely. Conditions should be soft, moist soil.

Emergent species (such as Phragmites) should be planted in saturated but not flooded soils

and allowed to grow stems with leaves that project above planned flooding levels the first

season. After stems reach 10-20 cm, water levels can be raised 4-6 cm above the substrate

and proportionately increased as plant height increases until desired elevations are reached.

After all planting is finished, the water level should be gradually raised to normal operating

elevations as the plantings grow higher but water levels must not overtop new growth

during the first growing season.

Note:

Inappropriate water levels can inhibit establishment and growth of desirable wetlands plants,

however unsuitable levels can be used to control prolific growth and spread of weedy, terrestrial

species. Flooding may retard invasion by terrestrial opportunists and deeper flooding may retard

undesired colonization of additional areas by planted wetland species.

7. WETLAND AND PONDS OPERATING GUIDANCE

7.1 Construction to commissioning - What to Check for:

Site establishment and layout

It is critical that site boundaries are established, demarcated and secure. Constant security

monitoring is highly recommended to ensure restricted access to the site. This will ensure that

incidents of theft, damage to infrastructure and health and safety incidents are mitigated and,

where possible, prevented. An established site layout must determine the various works, stockpiling

and compound areas. All benchmarks must be identified and documented. Site layout plans should

be drafted and conformance to these plans must be monitored.

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Excavations and earthworks

All excavations and earthworks must adhere to specifications relating to prescribed levels, health

and safety requirements, the stockpiling of surplus material and the quality of the material (clay,

topsoil, etc). Active measures must be taken during earthworks, dewatering and rain fall events to

mitigate and or prevent erosion or structural damage.

Infrastructure

Care must be taken in ensuring that the CWS embankments and flooring are correctly compacted

and sloped, using the proper material. Geosynthetic linings must be installed according to manual

best practice guidelines ensuring a smooth profile free of roots and vegetation. All pegging and

anchors must be thoroughly checked. Ensure that all cell floors are levelled and sealed prior to filling

with substrate.

All structures must have correct foundation preparation, adhere to prescribed spatial planning

requirements and the materials used for construction must be checked to ensure acceptable quality

standards. Prior to commissioning, all structures must be inspected to check for correct alignment,

levelling and functioning.

Planting

During planting phases, water depth and moisture of the substrate must be monitored regularly.

Weeds and other terrestrial or encroaching plant species must be removed, and the selected

vegetation must be regularly inspected to ensure adequate plant health and density.

Quality

Prior to commissioning, quality checks must be performed to ensure that each structural component

is fully functional and is correctly aligned with all other components within the system.

7.2 Water level management

Flooding often causes more problems for wetland plants during the first growing season than too

little water if the water has low dissolved oxygen content. The objective of water level management

is to create unfavourable conditions for terrestrial species by shallow flooding or saturating the soil

but not to stress wetlands species by deep prolonged inundation.

7.3 Wetland maturation

7.3.1 First six months

The wetland should be operated with clean water or very low-strength wastewater for the

first month after planting. During the fifth week, initiate operation with one-half strength

wastewater or with one-half the design flows and continue for three months.

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After the end of the fourth month, begin operation with full-strength wastewater or with full

design flows. Check proper operation of all piping, pumps and water control structures and

monitor vegetation.

7.3.2 After the first year of operation, the operation and maintenance typically consists of:

Site inspection of berms at least once a week should be conducted to check for any erosion,

seepage or animal damage

Berms should be mowed weekly

Water quality samples should be collected as needed

Routine weekly inspections are necessary to ensure appropriate flows through the inlet

distributor and outlet collector piping as well as leaks in the piping itself

Flow distribution within cells should be occasionally inspected to detect channel formation

and short-circuiting. Channels must be remediated by planting vegetation and soil filling

within the areas of concern

Grass and wetlands vegetation should be checked at least once a week to identify any visible

signs of stress or disease such as grass yellowing, chlorosis, leaf damage, etc

Should stress or disease be noticed, a specialist should be consulted

All built infrastructure such as pumps, valves, "T" fittings, etc. should be checked at least

once each week to ensure that pumps and all piping are operating properly (i.e., check for

clogging and make sure that the flow coming out of each "T" fitting is the same)

Sampling frequency may vary for different types of wastewater, however, the minimal

requirement should be at least once a month over a two to three year period. Weekly

sampling is recommended since it will provide more reliable data. Hammer recommends in

his 1994 guidelines that as a minimum, a composite 24-hour sample be taken on a week day

once per month and one grab sample once a month

Note:

Where plant cover is deficient, management activities to improve cover may include water level

adjustment, reduced loadings, pesticide application and replanting.

8. SUMMARY OF ACTION AND OBJECTIVES

This Schematic Construction and Operational Management Plan forms the basis of the proposed

Constructed Wetland System envisaged for Limpopo Dairies. It provides a detailed overview of the

type of structural interventions and processes required to implement a CWS that will successfully

contain, treat and recycle waste water in an efficient and cost effective manner using natural

processes.

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Should Limpopo Dairies decide to implement a CWS, the plan must be strictly followed, as all

interventions described in this document are of critical importance to achieving the desired

outcomes, and cannot be achieved in isolation to one another.

NCC looks forward to the opportunity of providing specialist services to Limpopo Dairies in the

detailed planning, engineering and construction of the proposed CWS.

9. FURTHER INVESTMENT CAPITALISATION

In communication with Limpopo Dairies, a number of additional opportunities were observed, which

should be considered in conjunction with the CWS development.

9.1 Biogas

The abundance of livestock manure on the property provides an excellent opportunity to explore the

viability of generating heat and electricity from methane emitted from the harvested biomass. The

filtering of biomass from the solids trap could be utilised as a component of the critical fuel mass

required to viably generate sufficient methane volumes to ensure a consistent flow of energy. NCC

would like to assist Limpopo Dairies in assessing the viability of such as exercise, should the

organisation deem it worthwhile. From the initial estimates received from Limpopo Dairies

Management, it would appear that 10 tonnes of wet mass manure produced by the operation per

day would warrant further examination into the concept.

9.2 Compost

The use of biomass harvested from the operation as compost is currently being undertaken. Further

biomass will be able to be added through routine maintenance of the solids trap, thus harvesting an

otherwise wasted resource. The easy maintenance of the screen should allow for fast and efficient

harvesting of the solids to be used for fertiliser. In addition, should biogas interventions be sought,

the spent manure can be used as fertiliser post methane capture.

9.3 River Water Treatment

As Limpopo Dairies is situated in a water stressed region, the use of a CWS to treat previously

unsuitable river water could be an option for further consideration. Through pumping this river

water through a CWS, the quality of the water could be improved to a level suitable for agricultural

irrigation.

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9.4 Proposed operations expansion

As discussed with Management at Limpopo Dairies, it is foreseen that Limpopo Dairies will be

expanding its operation, resulting in increased effluent production. NCC has made spatial and

structural provision for such an event. The extension of the facultative and polishing ponds, along

with increasing the number of vertical and horizontal flow trains to satisfy increased volumes will be

simple and cost effective to implement within the space surrounding the proposed CWS, should

production be doubled.

10. HOW CAN NCC HELP YOU

NCC, in association with our trusted partners, provide a range of services that are tailored to the

specific needs of our customers. NCC has a long track record of successful project management.

With extensive experience in the construction industry, NCC is well versed in planning, implementing

and monitoring projects at all levels and at varying scales. With our co-creative, pragmatic approach,

NCC is the ideal partner for project developers and land owners, to ensure that all project objectives

are successfully achieved.

10.1 Legal Services

Legal Advisory in association with our trusted legal associates

Licensing and permitting

Legal register documentation and compliance planning

10.2 Project planning Engineered designs

Project Programmes

Bill of Quantities drafting

Budgeting

10.3 Project management Pre-construction phase planning

Construction phase management

Operations training and commissioning

10.4 Monitoring and maintenance System inspections

Water quality monitoring

System maintenance

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11. DISCLAIMER

Whilst we understand the world as a set of related systems and appreciate the importance of the

identification and solution of problems, organisation and management of human resources,

communication, the collection, analysis, organisation and critical evaluation of information

documents, samples, specimens, worksites, worksite procedures, industry protocols, statutory

requirements, our information is based on our observations of data made available, the scope for

investigation and communication made available to us and / or information from other sources. We

give no warranty express or implied for information or advice given or opinions expressed, nor do

we accept any liability for any loss direct or consequential that may arise from whatsoever cause.

As biological, including crop, performance depends on the interaction between genetic potential,

physiological characteristics and the environment, we give no warranty express or implied for

biological or crop performance nor do we accept any liability for loss direct or consequential that

may arise from whatsoever cause.

12. LIST OF APPENDICES:

Addendums I and II: Spatial schematics

Addendum III: Schematic Overview

Addendum IV: Legislative requirements