Subsurface Drip Irrigation of Omaha Golf Course Fairways with Treated Effluent

ABSTRACT

In 1999, in addition to the existing 825 lots developed in the 1970’s, a new 600-lot subdivision was commenced at Omaha Beach. Omaha Beach is a popular recreation beach community north of Auckland. In conjunction with the new residential development the existing 9-hole golf course was expanded to a full 18-hole course. The existing wastewater treatment and disposal infrastructure were upgraded and expanded.

Omaha is a horticultural and agricultural area with a shortfall of groundwater limiting extensive local irrigation. After evaluating the irrigation alternatives, in this case a key component of both the wastewater plant upgrade and the new golf course expansion was the subsurface drip irrigation of treated wastewater under the new fairways and surrounding landscape.

The system has operated successfully since installation in 2002. It includes buried drip irrigation incorporating sustained release herbicide impregnated drip emitters and antimicrobial lined tubing. As a result of this initial success the system was expanded in 2004 as part of the Omaha South Stage 2 development.

KEYWORDS Subsurface drip irrigation (SDI), golf course, effluent reuse, Omaha

Introduction

Omaha Beach is a popular coastal residential resort located on a narrow spit of land about an hour north of Auckland, near Warkworth, and is situated on environmentally sensitive east coast sand dunes. The Omaha spit comprises sand over a peat base and is edged by Little Omaha Bay on the coastal eastern side, the Whangateau Harbour on the western side and the mainland west of the harbour.

A causeway about half way along the spit crosses the harbour, connecting it with the mainland. North of the causeway on the spit is the original residential development, which included a nine hole golf course, while the southern end of the spit is the site of the latest development.

The original Omaha North development was commenced in the 1970’s and grew to consist of approximately 825 lots near the northern end of the beach. A sewage treatment and disposal system was constructed in 1989 to meet the dual needs of both sewage treatment for this Omaha community, and a reclaimed water supply for horticultural activities on farmland immediately adjacent to the treatment facility. In conjunction with this original residential development a ninehole golf course was constructed in 1973. This system incorporated a separate groundwater bore drawing 3,000 m3 /year which was used to irrigate the greens by pop-up sprinklers (outside of opening hours), and the tees by handheld hoses connected to quick coupling valves. The fairways are not irrigated.

In 1999, a further development of 600 residential lots was commenced at Omaha South. In conjunction with this, a new nine-hole golf course was built in 2002 adjacent to the existing course, to provide a full 18-hole course with the original and new courses being linked at the causeway. Some of the fairways, rough and surrounding landscape areas of this new course are irrigated with subsurface drip irrigation (SDI) using treated effluent from the newly upgraded and expanded community wastewater facility. When planning the additional subdivision the new and extended golf course was seen as an important asset to enhance community recreational values. Omaha is a groundwater short area with very limited fresh water irrigation supplies and it was considered important that the new golf course incorporate effluent irrigation if practical. An area of the golf course was also required to supplement the mainland irrigation disposal system at the wastewater treatment facility as there was not sufficient land available for year round disposal of the total projected volume of the future extended community population. Any treated wastewater irrigation disposal system on this new golf course had to fit with both the ambiance of the new development as well as associated environmental and public health sensitivities.

Wastewater Treatment

The Omaha communities collect water from roof/tank supply for household potable use and a community water supply scheme is not planned. The average volume of wastewater for disposal is projected to vary from approximately 165 m3/day in year 2000, to 740 m3/day in year 2015, and a holiday flow of 1,500 m3 /day. The wastewater collection system consists of a conventional gravity reticulation system through both the original Omaha North and new Omaha South subdivisions supplying a pump station on the spit. This then delivers the raw untreated wastewater to the wastewater treatment plant, which is located at Jones Road (on the mainland), via a PVC rising main. The original rising main was 200mm but this was replaced in 2002 by a new larger capacity 300mm line to cater for the higher volumes to come on stream with the larger future community.