COP Brief Development

• suitable to the highly sensitive ecological, archaeological, cultural and social values of the Park;
• affordable in terms of development and operation;
• sustainable in terms of environmental effects, discharge quality, low risk of malfunction, highly flexible operating requirements, low maintenance requirements;
• acceptable to Park visitors, to avoid the problem of visitors “going bush" for ablutions because they were not familiar with the installed facilities or the facilities were not providing a high enough level of service;
• practical and effective in a physical environment that has extremes of weather, rough topography, sensitive ecology and receiving waters;
• high archaeological values, water access only, no power, limited fresh water, with occupation concentrated near sea level; and
• installed while a high level of ongoing use was likely.

COP Planning for practice

Environmental Awareness

The first stage of the project included a review of the existing facilities and situation in the Park and an assessment of options for treating and controlling wastewater. DOC had a considerable amount of information on environmental issues within the park and other activities were undertaken to gather information including:

• A detailed assessment of physical characteristics including geology, hydrogeology, topography and land cover.
• A detailed assessment of present and future usage and the need to monitor usage.
• An assessment of social and cultural characteristics, both historic and present.
• A review of relevant legislation, standards and guidelines.
• An onsite assessment accompanied by DOC staff including an archaeologist and Iwi representatives.
• Experience of MWH in both human waste and sewage management, and particularly in developing solutions in National Parks and other back country locations.

COP Outcome development and evaluation

Key information was presented to all stakeholders at a workshop.

COP Planning for practice

Project risks were identified in partnership with DOC during the planning stages, and later during construction with the contractor.
A risk management strategy plan for the entire Park was developed. The following steps were taken during the planning stages to identify and assess project risks.

• A review of available literature. This enabled the team to identify risks and known incidents experienced in the Park and similar locations.
• Investigating previously installed backcountry wastewater solutions to obtain information on the performance of systems.
• Using a multi-disciplinary team, that comprised DOC staff and consultant specialists.
• The multi-disciplinary team completed comprehensive field studies together, enabling team interaction, understanding of risks from different perspectives and identification of the most appropriate mitigation measures. These mitigation measures were influential in the selection of solutions.
• A review of park user information in this location and other sensitive locations to assess user feedback and perceptions and identify patterns.
• Initial site visits to assess the physical geography and identify existing constraints and appropriate mitigation measures.
• Detailed follow-up site investigations for identified areas of risk, including visitor numbers, geology, groundwater levels, and consultation with affected parties, in particular tangata whenua.
• Researching possible solutions to determine their applicability to the specific issues identified.
• Completing a strategy for the Park which established development principles and specified methods for applying these principles, establishing strategy options and evaluating options including cost estimates at each site.
• Preparing a design report that detailed the proposed solutions for review by DOC. This enabled confirmation of the selected designs prior to preparing tender documentation and proceeding to contract. It also allowed design assumptions to be recorded, potential issues for monitoring during implementation to be noted, and provided a basis for final DOC review of the proposed solutions before committing to construction.
• Proactive consultation by DOC with tangata whenua, including site visits to explain, in the field, the issues and the proposed solutions.
• Risks were documented in the Sewage Disposal Investigation Report and reviewed during the course of the project to ensure active management of the risk profile.
• A workshop was held with DOC staff to select the best options for the Park and each site.

COP Outcome development and evaluation

Work in the first stage identified a number of risk factors which resulted in further investigations.

• The completion of a comprehensive monitoring programme to assess projected user numbers and demand patterns.
• The need to gather user numbers from those sites where access was not controlled by DOC (eg. water ski beaches and kayaker camp sites).

Other risks identified and quantified included.

• Site specific data such as groundwater levels, geology, topography, cultural issues and all existing constraints and appropriate litigation measures.
• Contractual risk was highlighted in the contract documents to allow construction risk to be placed where it could be best managed including interruptions to construction due to Iwi and archaeological finds, the need to complete installation before overseas visitors returned to the Park, the limitations of water access, the environmental risk of operating in the Park, and the lack of power.

The design development also quantified and addressed the risk from system failure, remote location for servicing, high seasonal use, noise and other environmental constraints.

COP Outcome development and evaluation

 

Estimating projected user demand

The project included sites controlled by DOC and sites only accessed by kayakers and water skiers. Knowing accurate current and projected demand for toilet and washing facilities in the Park was critical to the success of the facilities design. As existing information was insufficient, DOC made the decision to delay the project for a season so that a detailed monitoring programme could be completed. Analysis of the information gathered enabled appropriate decisions to be made on the nature and capacity of the onsite treatment systems selected and the energy needed for pumping.

COP Planning for practice

Legislative requirements and constraints

A complex array of legislation applies to activities undertaken with the Park, including the National Parks Act, the Conversation Act, the Foreshore and Seabed Endowment Reinvesting Act, Historic Places Act, the Health Act, the Building Act, and the Resource Management Act. Relevant legislative requirements were identified in the Stage 1 sewage management 'issues and options' report and appropriate management procedures were determined and documented in the Sewage Management Plan.

COP Outcome development and evaluation

Cultural values

Historical occupation along the coastline by the tangata whenua meant there was potential risk associated with archaeological sites being disturbed or affected during the development and operation of wastewater facilities. The discharge of human waste is of particular concern to the tangata whenua. DOC representatives consulted extensively with Iwi to identify issues of concern and agree appropriate design and implementation requirements. During construction an Iwi observor an archaeologist and a DOC staff member were present to monitor the construction process and offer immediate advice in the event any archaeological sites were inadvertently disturbed.

COP Brief development

Physical constraints included the generally low elevations of the hut and campsites, the proximity to coastal waters, estuaries or rivers, the bush-covered countryside, the sandy soils and estuarine sediments in coastal areas, the hilly topography, the limited areas of flat land, and in some places shallow rock. Site investigations characterised the physical constraints and on-site concepts were developed that were appropriate. Important aspects of the solutions were:

• containing waste where there were unstable environments (e.g., toilets on sand dunes or very steep topography);
• creating a considerable separation distance between effluent disposal areas and surface waters;
• using solar power with back up generators to allow pumping;
• disposing of effluent below ground.

Access issues

Within the Park there are no infrastructural services such as roads, power supplies, telephones, water supplies and sewerage. Development in the Park needs to provide for such services during construction and in operation. Solutions adopted needed to have low water requirements, as natural supplies can be short-lived or run low during the summer. The provision of power reflected the needs of users at the site.

Aesthetic requirements

People go to National Parks to enjoy the natural environment. Developments, especially those for sewage management, need to minimise, as far as practicable, adverse aesthetic effects such as adverse visual effects, problem odours and noise. Solutions were designed to avoid or minimise visual effects, malodours and noise.

Ecological values

The Park contains native vegetation which must be protected. The introduction of weeds and the contamination of water during construction were unacceptable threats which were addressed through appropriate design and contractual requirements.

 

Economic constraints

The Park is isolated from conventional infrastructural services, so any development has the additional expense of transport and providing for other such services, during construction and operation. It was important for DOC that economically feasible ways were identified for providing for service and maintenance requirements. In addition, the operation of Park services could not be interrupted.

Innovative solutions adopted to minimise development and running costs included the use of duty and standby septic tanks, enabling considerable flexibility for pump-out events and providing overall financial benefits. The approach also reduces the risk of septic tank overflow, provides greater storage capacity in the event of pump malfunction and generally enhances the robustness of an onsite solution for a backcountry environment with high usage.

COP Outcome development and evaluation

Duty and stand-by septic tanks

Use of duty and stand-by septic tanks would deliver a number of environmental and economic benefits, including reducing the risk of septic tank overflow, providing greater storage capacity in the event of pump malfunction and generally enhancing the robustness of the solution. The dual septic tank system will also enable operators to manage toilet and washing facility discharges in a manner which avoids emergency pump-outs or the uncertainty of knowing when a septic tank will be full. The distribution manhole allows the hut warden to redirect flows simply when required. DOC has already benefited financially from this stand-by solution as expensive barge and associated pump-out facilities were not required during the 2001/2002 high season.

Solar power for pumps

Two types of solar powered effluent disposal systems were considered. The first involved a pump storage system where effluent was pumped to an elevated storage tank during hours of sunlight. The other involved storing electricity in batteries to enable pumping over a longer period. The latter system was selected and involved close liaison between electrical and sewage designers to optimise solar power availability, battery storage and emergency generation, sewage storage and peak use loading.

Ventilation enhanced vault toilets were installed at two locations because there was insufficient water for flushing or because the environment was unstable (sand dunes) and a removable, containment facility was considered the best solution. The vault toilet provides storage for several years. The system also includes a large, solar fan assisted ventilation system designed to avoid odours back-venting into the toilet cubicle. This was considered critical and has received much praise by users during the 2001/2002 season. The vaults have a detachable superstructure and both the vault and superstructure can be relocated by helicopter.

Toilets blocks have low flush toilets and waterless urinals to minimize water demand and to minimise hydraulic sewage load.

Subsurface, dripper effluent disposal systems were installed at the two largest sites. Dripper irrigation of septic tank effluent is a new technological system that enables effluent disposal in a controlled and sustainable way in a difficult topographical environment.

COP Outcome development and evaluation

The project was completed in time for the 2001/2002 summer season and was within the approved budget. Anecdotal evidence from DOC and visitors confirms the facilities provide an excellent level of service. To date the systems have proved reliable and are performing better than expected, particularly with respect to adequate storage and solar power performance. The buried dripper feed irrigation fields are disposing of the effluent without odour or runoff. Minor adjustment is to be undertaken at Bark Bay to balance pressures but monitoring has detected no adverse effects in the ground or surface waters.