Bluestone Resorts Ltd

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Bluestone figure 1

Figure 1 Bluestone Resort Ltd location

Bluestone National Park Resort is operated by Bluestone Resorts Limited (Bluestone), located in Pembrokeshire, South West Wales. The 500 acre park is visited by 350,000 visitors a year and has 500 members of staff. The holiday complex has 300 chalets, 5 restaurants and several activity and adventure centres including a water centre, spa and high ropes. The occupancy rate for 2013 was 89% and therefore offers an important all year centre for over 100,000 residential visitors to stay per year. Bluestone is owned by a management team with the founder William McNamara as the chief executive. The site is located within easy access to the M4 corridor and offers a central location for access to the tourist attractions of Pembrokeshire, Carmarthenshire and Ceredigion.

Bluestone figure 2

Figure 2 Bluestone Lodges picture from website The Resort – On Park Facilities – Bluestone Wales

Bluestone is not located near a mains public sewer and therefore the company has to provide its own private sewage treatment work (STW) to treat and discharge the foul effluent to the Eastern Cleddau. The discharge of effluent to the watercourse is authorised under a permit issued by Natural Resource Wales. The stringent conditions of the permit require Bluestone to treat the effluent to a high standard and the company has opted for a Membrane Bioreactor (MBR) system. The specification for the MBR plant was drawn up and installed under contract at a cost of around £1 million.

However the STW failed to operate to the specification to which it was designed and problems with performance were occurring before the system was fully commissioned by the contractors. The risk of failure of the works and the potential noncompliance of the permit was minimised by the contractor by tankering partially treated effluent to the nearest Dŵr Cymru Welsh Water sewage treatment works. The cost of tankering partially treated effluent was estimated at £1 million per year. This situation was unsustainable and Bluestone wanted a long term solution.

An option considered was to continue with the Bio reactor section of the existing STW but to polish the final effluent using a biological treatment process based on a reed bed system, frequently referred to as Integrated Constructed Wetlands (ICW). An interim sewage treatment measure was installed to protect the nearby watercourse and to ensure that the resort was able to remain “open for business”.

Bluestone figure 3

Figure 3 Integrated constructed wetland installed to remove nitrates and other contaminants such as sediments and phosphate from farm/farm land runoff. Picture taken by ADAS

The ICW treatment of contaminated effluent operates by the holistic use of land to control water quality through various physical, chemical and biological processes involving aquatic plants (predominantly macrophytes), algae micro-organisms, water, soil and sun (UV photodegradation). The plants commonly used in ICW are reeds but there are many different species of plants that can be used (see fig 3). The extensive root system of the plants allows the percolation of the effluent and the incorporation of oxygen to produce aerobic conditions. Here oxygen-loving microbes change many compounds such as ammonia into nitrates which act as a fertiliser for the reeds. The biological activity of the microbes is crucial to reduce the severity of chemical reactions in the environment such as Biochemical Oxygen Demand (BOD), Chemical Oxygen Demands (COD) and transform metal compounds and other potentially harmful substances.

The potential “Payment for Ecosystem Services” (PES) for integrated constructed wetlands is the capture of carbon, nitrates, phosphorus, sediments and their effect upon water resources and biodiversity enhancement. However the design specification and track record of the ICW supplier failed to meet the Bluestone standards or specification and this treatment option was discounted. The solution was to modify the existing system and install primary and secondary treatment using sand filtration and UV disinfection process. The design of the revised works, installation and commissioning of the new STW was undertaken in house i.e. by Bluestone staff.

More recently Catchment Sensitive Farming in England is looking to implement ICW as a method to abate the impact of farm wastewaters. At present the use of ICW is limited to those waters that are not heavily contaminated with pollutants. The use of ICW may be deemed “Best Practice” in England in the near future and the potential for “additionality” may come into question under a PES scheme.

The two aims for the Bluestone Resort case study are:

  • to ascertain the challenges and lessons learned, as experienced by the company, when considering the installation of an integrated constructed wetland as a method of tertiary sewage treatment for Bluestone National Park Resort
  • to evaluate the treatment opportunity of wetlands for the removal of nitrates and the potential reduction in load of nitrate to the Cleddau catchment

The (ICW) treatment process relies on the biological activity of plants and microbes to treat effluent. ICW is commonly used by utility companies for the “polishing” or tertiary treatment of sewage effluent prior to discharging to rivers and coastal waters. Initially the Bluestone ICW concept for offsetting was considered for the sequestration of carbon by a process whereby sewage, comprising of organic matter, is broken down by the fauna and flora of the wetland. As part of this process, plants photosynthesise and carbon dioxide is captured and fixed within the plant structure as sugar and ammonia from the sewage is transformed into nitrates which are taken up by the plants. However the interactions which occur in the ICW are much more complex and involve the following processes;

  • Physical filtration to reduce sediments and solids by the vegetative masses acting as a baffle to slow the water flow down and permit the sediments and solids to settle in the wetland structure.
  • Settlement of suspended solids by reducing water flow in long shallow lagoons
  • Uptake and transformation of nutrients and other contaminants by plants, microbes
  • Accumulation and decomposition of organic matter including adsorption to aggregates
  • Microbial mediated processes such as nitrification (aerobic) and denitrification (anaerobic) processes for the cycling of nitrogen
  • Chemical precipitation
  • Treatment of pathogenic agents

The estimated construction cost of installing an ICW ranges from £25 per m² to £100 per m² depending on the level of treatment required[1]. However, it is not clear if these costs include the value of land take up and ancillary costs such as fencing and maintenance.

In 2013 Lancaster University undertook a study of mitigation options for phosphorus and sediments removal using wetlands (MOPS2). Two studies for nutrient removal were undertaken; Crake Trees Manor in Cumbria found that 30 tonnes of sediment was trapped in the wetland over the 3 year period and this included 100 kg of nitrogen (30 kg of phosphorous and 1200 kg of carbon). At Whinton Hill Farm 70 tonnes of sediments was captured, including 300 kg of nitrogen which equates to a 35% reduction in Total Nitrogen (as well as 100 kg of phosphorous and 4000 kg of carbon).

The Ofwat report on the cost of reducing ammonia nitrates and BOD in sewage effluent (Ofwat, 2006)[2] shows that the equivalent annual cost (EAC) for reducing nitrates as shown in Table 1.

Table 1: Estimated costs for reducing nitrates in sewage effluent for two average size sewage treatment works (OFWAT 2006)

Bluestone table 1

The cost benefit of meeting Water Framework Directive based on the cost of nitrate removal at a water treatment works in 2009 was estimated at £0.041 million[3]. A study of the use of ICW for the treatment of Domestic Wastewater was undertaken in Glaslough Ireland between 2008 and 2011[4] cites that the mass removal of 90% of suspended solids, organic matters and nutrients during the monitoring period. However, the nutrient removal rate was largely dependent on temperature, showing a reduced removal rate under freezing conditions and under higher hydraulic loading rates. This could be overcome by increasing the treatment size surface area.

Consideration for maintenance and appropriate licencing and permits for ICWs should be accommodated in any development. Licence and permits may be required from the Environment Agency or Natural Resources Wales for impoundment, sludge management and discharges, consents may be required from the Local Authority for land drainage matters.

The maintenance programme for an ICW will vary depending on the nature and size of the wetland and the strength of the waste water discharging to it. Maintenance can include pipework maintenance, flow controls vegetation management to ensure plant growth, sediment/sludge removal and disposal/recovery, embankment maintenance, site security and access and ICW performance monitoring. In most instances the monitoring of a farm wetlands performance is measured by the inflow and outflow waters. Other parameters such as a change in vegetation species and cover, change in water colour, presence of sewage fungus at outlet, smell and loss of vegetation through outlet will also indicate a level of underperformance of the wetland.

For ICW sludge disposal or recovery, it is advised to contact NRW or the EA to ensure that all environmental legislation and agri environment scheme criteria are adhered to.

[1] Wildfowl and Wetland Trust: Constructed Wetlands treating agricultural water pollution and enhancing biodiversity

[2] Ofwat (2006) What is the cost of reducing ammonia nitrates and BOD in sewage effluent treatment works effluent? Prepared by Oxera for Ofwat

[3] Environment Agency (2009) Valuing the benefits of reduced drinking water treatment as a result of WFD measures.  Final Report June 2009.  Report prepared by Entec UK Limited

[4] M. Dzakpasu, M. Scholz, S. N. Jordan and V. McCarthy (2010) Intergraded Constructed Wetland for Rural Domestic Wastewater treatment: A full scale study in Ireland by Dundalk Institute of Technology.

The initial thinking for the Bluestone eco-offset programme was using ICW for the capture of carbon. However there are other opportunities associated with the primary PES scheme including:

    • The capture of carbon during plant growth
    • The conversion of ammonia to nitrates which acts as a fertiliser.
    • The precipitation of phosphorus
    • The use of a “Blind system” to modify water flow through
    • Reduction of sediment loss to the rivers

The sequestration of carbon could be deemed an eco-offsetting parameter for this project. As seen in section 2 the effectiveness of wetlands for carbon sequestration over a 3 year period is estimated around 1000-4000kg of carbon over a three year period.

The Woodland Carbon Code (WCC) is based around the creation of woodland to remove carbon from the atmosphere. The main buyer or investor would be retail companies which require the offset for carbon and the broker or intermediary is the Woodland Trust. In 2012 there were 89 WCC projects and there may be an opportunity for Bluestone Resorts Ltd to join this scheme if they have a tree planting programme underway.

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Figure 4: Forestry Commission Woodland Carbon Code UK Woodland Carbon Code


Table 2 shows the potential fixing of Carbon in tonnes per hectare.

Table 2: Carbon stored by British grown trees (extract from UK Woodland code carbon stored in British trees)

Bluestone table 2

There are two main participants that have remained in place for the duration of the STW uprate at Bluestone, namely Bluestone Resort Ltd as site owner and permit holder, and Natural Resources Wales. Contractors, design consultants and suppliers have included Carillion and Dŵr Cymru Welsh Water.

There are a number of issues which need to be considered and addressed with regard to offsetting

Planning:  The design and construction of the sewage treatment works was initially in the hands of a third party and in hindsight Bluestone Resort Ltd should have had a greater involvement at the planning and set up stage.

Design and Specification:  The STW at Bluestone is large enough to meet the threshold of the Urban Waste Treatment Directive of 2000 population equivalent and this equates to a medium size town bigger than Fishguard. However, retrofitting a new sewage treatment works while trying to maintain effective treatment of sewage from 350,000 visitors per year is difficult. The initial construction has been found not to adhere to the plans and drawing and the revision of these plans and the exploration of the sewerage has been time consuming and expensive.

Plant operation :  A membrane filtration system is a technically difficult treatment plant to operate and manage. These systems were installed by many utility companies at sewage works as a method to primarily remove microbes. However the utility companies are now removing these at some works and replacing with alternative treatment processes. The original contractor in charge of the MBR did not provide adequate instruction to operate and maintain the system.

Commissioning of plant:  The commissioning of the new plant and the transfer of all flows through the new works is time consuming as all processing have to be trialled, performance monitored and verified before complete transfer can occur. The commissioning monitoring will continue for at least a year so that the performance of the works can be monitored closely and optimised where possible. A full year of monitoring is advised so that any high loads which may occur during the peak tourist season can be evaluated and accommodated for the future.  Ongoing discussion with the regulator, Natural Resources Wales, has helped to facilitate this process.

Maintaining full treatment:  Bluestone has continued to manage the effluent generated at the resort while improving the existing sewage treatment systems. This has been extremely challenging but the advice from Natural Resource Wales has been valuable in allowing the site to remain open.  The inclusion of an ICW to “polish” the final effluent produced at the tertiary treatment works would require a maintenance schedule to be incorporated within the design, construction and ongoing cost for the wetland. The use of the sludge as a fertilising material could represent a further eco-offset as an inorganic fertiliser contribution.

The cost of the commercial merchant figures for fertiliser price (17 March 2015) is seen in Table 3.

Table 3: Average commercial price for fertiliser march 2015

Bluestone table 3

Funding:  The cost of the retrofit of the existing works is about 50% of the initial budget for the MBR plant. This additional cost will not add value or increase value to the bottom line of the business. However treatment of sewage in an area where mains drainage is not available to imperative if the site is to remain open. Tankering of sewage was undertaken for about a year but this was unsustainable. Negotiations to secure additional funds to improve the STW was made a top priority for the new management board as led by William McNamara. The cost of constructing an ICW can range between £25/m ² and £100/m ² excluding other ancillary costs. However the Bluestone team has used ingenuity and commitment to keep the costs as low as possible.

Environmental Constraints:  A designated shellfish bed is located downstream of the discharge site from Bluestone National Park Resort. This places strict controls for effluent quality as stated in the permit. The EPR permits conditions include effluent discharge volume which must not exceed 400m³ per day, BOD 12 mg/l, Ammonia 5 mg/l and Suspended solids 18 mg/l. This permit will have been set in accordance with environment protection standards included.

Removal of surface water:  The effluent directed to the STW has, in the past, had a large proportion of clean surface water. Clean water from land, ground water and impervious ground can enter the dirty water system through the connection of surface water drains to the foul sewer. This can lead to excessive treatment costs. Bluestone has endeavoured to remove all surface water from the foul system but the impact of this work is not yet understood. The permit is for a specified volume of effluent i.e. 400m3 per day but if the volume is reduced then there could be a reduction is permit fees and associated charges and also this site could fall below the Urban Waste Water Treatment Directive threshold of 2,000 population equivalent.

Endorsement for wetlands:  When considering the ICW solution, Bluestone undertook some research about the supplier company and the use of ICW elsewhere. This findings of the research were not conclusive and very little historic evidence was made available that indicated this process could achieve the level of treatment required for a site upstream of a designated shellfish bed. Check for “track record” was an important tool for Bluestone to see if there was evidence to collaborate the assumption offered by the ICW designer. There was insufficient collaborative evidence for Bluestone to invest in a treatment system that might not work.

Market of Payment for Ecosystems services:   At the time of the sewage scheme development, with the added pressure of maintaining an operational works under construction, there was no visible market place or buyer for carbon or nitrogen, to justify overturning the findings of lack of endorsements for the process.

Possible Resolutions

Bluestone Resort Ltd is committed to the corporate sustainability agenda and will be considering the inclusion of the ICW treatment process as a possible final effluent treatment process. It is envisaged that with careful design, the constraints of the soil type, ground conditions and local topography can be overcome so that some, if not, all of the treated final effluent currently discharging to a tributary of the Eastern Cleddau can be passed to inland waters.   At his point there will be further reduction in ammonia, phosphorus and sediment loads to the river which could be deemed as an “offset”.

The main opportunities for securing credit for environmental offsets in this model are:

  • The fixation or sequestration of carbon by the reeds in the ICW
  • The oxidation of ammonia to nitrates thereby reducing the need for fertilisers and the loss of gaseous nitrogen
  • The sedimentation of phosphorus
  • The prevention of sediment loss
  • The reduction in microbes particularly faecal indicator organisms
  • Biodiversity enhancements of the ICW
  • Potential energy crops for ICW such as willow or miscanthus
  • Flood risk abatement
  • The economic value of these potential credits is dependent on the availability of buyers at a local scale. This particular case study highlights cost-effective action for an individual business but in principle there is an opportunity for contributions from others, including the water utility company (nitrate, phosphate, sediment and faecal indicator organisms), wider business or energy generating companies (carbon and energy crops), wildlife trusts (biodiversity) and insurance companies (flood risk abatement). It is unlikely that any individual scheme could access all these markets but all opportunities should be explored.

More widely, the use of wetland creation to address water quality problems should be explored. Given the multiple benefits in terms of ecosystem services and limited data on their efficacy, it may be that public funding is an important component of establishing these systems unless there is a compelling economic case for action by a single company as in this case study.

The opportunities at the present time are fairly limited as Bluestone has been working on the sewage treatment project for a few years and the required capital investment for this programme is estimated at £1.5 million. However they will continue to explore the possibility of directing some, or all, of the final effluent to a wetland treatment option. Also, as part of the corporate sustainability agenda the company may incorporate this work and offer information on the corresponding benefits to the environment as part of the visitor welcome pack and website.

The success of Bluestone Resorts Ltd private sewage treatment project is marked by the ability to continue to treat sewage effluent for 350000 visitors every year while constructing a new sewage works. An instrumental factor in overcoming the challenges that this raises is the continuous dialogue between Bluestone and Natural Resources Wales.

The development of a sewage treatment project from inception to completion exceeded the project schedule. The commissioning phase of the sewage treatment works is one year. This highlights that any future scheme that may arise under PES should be realistic about the length of time it requires to achieve full operational status.

The full cost of the Bluestone sewage scheme is estimated at £2.5 million including the effluent tankering costs as paid by the contractor. If this total cost is accepted then the scheme on a 3 year pay back term equates to £2.30 per visitor. Ongoing costs for permits fees, works maintenance and operational costs will be in addition to this.

The costs of a new ICW, as a tertiary treatment cannot be estimated at this stage as the design specification will be dependent on the performance of the new upstream works. However if wetlands are to be considered for a future PES scheme, the higher installation cost of £100m2 may be an appropriate estimated cost. A direct comparison with the OFWAT treatment costs for nitrates, is of value but further work is required to provide a valuation of the complex multiple benefits and the operational/maintenance requirements and costs of an ICW proposal.

The interest in the use of ICW’s, within sustainable drainage schemes and as part of pollution abatement, has recently regained new enthusiasm. The recent inclusion of wetlands as part of the Countryside Stewardship Scheme in England reflects this and may encourage the acceptance as a method to reduce the impact of diffuse pollution from agricultural premises.

However there is still a cautionary approach with the implementation of ICW’s use and more guidance for the installation and application from Welsh Government and the regulators may overcome this reticence and help to support the acceptance as a sustainable technique for natural resource management. When the guidance, planning policy and regulatory position is made clear then it is anticipated that ICW may be become an accepted technique of a water quality improvement and the faith in ICW as part of a PES scheme enhanced.