Mangawhai Heads Motor Camp – Mangawhai Heads
The Mangawhai Heads Motor Camp is the largest camping facility in the Northland Region using an on site wastewater management system. It is situated at the mouth of the Mangawhai Heads harbour, which is about 1½ hours north of Auckland. This camp covers an area of approx. 10 hectares and consists of three distinct areas of wastewater production.
The camp has had a long history of problems prior to the installation of the Innoflow wastewater management system. Being a local authority facility the repeated contamination of the Mangawhai Heads harbour was not acceptable and a long term solution was required urgently.
The greatest site constraint was that the soil and sub-strata are predominantly sand. The danger of short circuiting and contamination of the ground water (and subsequently the harbour) had to be mitigated. In addition, the camp operator had limited land available for a treatment plant or disposal field, without significantly reducing the area available for camping.Using this set of criteria Innoflow Technologies NZ Ltd. (ITNZL) produced a wastewater management solution that met with the business’ operational limits, the council’s environmental concerns and the campers’ aesthetic and practical expectations.
The existing geography was assessed and found to be suitable for the installation of point source primary treatment and Modified Effluent Drainage System (MEDS) pumped to a Bottomless Packed Bed Reactor (bPBR) treatment plant. This system acts as the final treatment point also, therefore no additional land was required for disposal.This is the first installation of a commercial bottomless PBR in New Zealand. The following details the system components and technical specifications. Also shown are the design constraints for this project.
| Constraint | Solution | Comment |
| Limited area for treatment plant and disposal | Utilise sand on site to construct bottomless packed bed reactor | Use of the existing sand also meant significantly lower capital costs |
| Harbour nearby with high water table | Use PBR technology to ensure high level of treatment to mitigate possible contamination | The setback distance from the beach was only ~15 meters |
| Maximise land available for camping | Use point source primary treatment and bottomless PBR to eliminate requirement for large disposal area | Camp sites are located within ~5m of the treatment plant |
| Highly seasonal loading | Use passive PBR technology with 100:0 turn down ratio to ensure consistently high treatment level | Flows range from the managers house over winter to well over 700 campers peaking over the New Year period |
Table 1: Design Constraints
The raw effluent was collected at each point of production in a series of septic tanks. The septic tanks provided primary treatment and screening with the Biotube® Effluent Filter. Orenco screened pump vaults with submersible turbine pumps were used to pump the screened effluent to the bPBR.
The screened effluent was timer dosed to the bPBR through a series of hydraulic sequencing valves to provide a thin film application over the surface of the reactor.
| System Component | Specification | Comment |
| Design Flow | 100 m3/day | Varies from a minimum of ~700 ltr/day to its peak over the Christmas period |
| Primary Treatment | 189 m3 Septic tanks | This consists of 7 x 27 m3 septic tanks positioned at three points around the camp |
| Delivery line | 63 mm Alkathene | 50 mm alkathene was used for the shorter runs |
| Primary filters | Orenco Biotube Effluent Filter | Model # FT1572-54 (1.83 meter high) |
| Delivery Pumps | 8 x Orenco turbine submersible | At peak – 6.2 hours run time per day @ 0.375 kW per pump |
| Packed Bed Reactor Area | 1250 m2 | The bed was covered with a 100 mm layer of the existing soil excavated from the site |
| Water meter model | 50 mm vane type | These were retro-fitted in Dec. 2000 to provide information for the renewal of the resource consent |
| Sequencing valve | Hydrotek V6606A | These were critical in allowing the use of single phase pumps, by rotational dosing of the rPBR |
Table 2: System Summary
One of the keys to achieving a controlled level of treatment consistently is the distribution of the effluent over the top of the reactor. The distribution system consists of a computer designed lateral arrangement and this is fed by a series of 8 sequencing valves. Each of the sequencing valves has six outlet ports and is operated by a separate pump at the primary treatment stage delivering a calculated volume of liquid using timer controls.
Using this method the packed bed reactor receives a controlled biological loading and will maintain a high level of treatment in the long term. The local authority has four monitoring piezometers installed around the plant and tests for faecal coliforms. The most recent results show no adverse impact on the receiving environment.