Historical Background to the Parkland, Pond System, and Stormwater Design

Boet Grobler, the General Manager of the HOA, recently asked me for my view on the Parkland, specifically the ponds, from their inception to today. 

It was a worthwhile exercise as it required me to record, in a logical order, my recollections but also to dig into old reports, legal documents and correspondence. 

I also discussed it with my brother, Gray, who was the Marketing Director of the Thesen Islands Development Company. He needs to be credited as the person more responsible for the lovely 11 ha of open space we enjoy than anyone else involved in the redevelopment of the island.  

Here is what I sent Boet on 19 May 2026: 

As requested, below is a summary of the history and original purpose of the Parkland ponds and stormwater system. However, it is difficult to separate the physical history of the ponds from the broader history of the Parkland itself, as the two are closely intertwined. The Parkland arose directly from the remediation strategy for the contaminated wood treatment area, and over the years the area has also become the subject of recurring development proposals and community debate. I have therefore included not only the technical and historical background to the ponds, but also some of the context that explains why the Parkland remains such a sensitive and strongly contested issue for many members today.

Origins of the Parkland

The early layout plan for the redevelopment of the island does not show a Parkland or Bird Reserve, only waterways and houses in the space where the Parkland and Bird Reserve currently are. This was the layout shown in the sales brochures when the Thesen Islands Sales Centre opened at the end of 1998. See here: How Thesen Islands would have looked...

When the extent of the polluted area, 11 ha of a 91 ha island, was confirmed in 2001, Barlows, the seller,  agreed to pay for the clean-up of the contamination and indemnify the buyer, the Thesen Islands Development Co (TIDC), “against any claim now or in the future arising from the contamination/pollution.” 

Opponents of the redevelopment were raising concerns about contamination in an effort to try and stop the redevelopment.  Gray Rutherford, the board member of the TIDC who was responsible for the Marketing, proposed to the TIDC board to renegotiate a lower purchase price for the island with Barlows and to turn the polluted area into a Parkland and Bird Reserve. The value of the island now being lower as fewer stands could be developed.

This was accepted by the TIDC board and a lower price was agreed by Barlows. The statement by opponents that the buyers were buying contaminated/polluted stands was demolished as no stands on contaminated/polluted land would be sold.

The large Parkland became a popular reason for buying a stand on Thesen Islands. Stands overlooking the Parkland commanded a premium price. It was intended as an open nature area with only low impact recreational use. The Parkland was understood as a permanent open space with environmental, visual, and amenity value. It was not understood as vacant land reserved for future development by the HOA. Many homeowners, extending well beyond the original purchasers, bought their properties in reliance upon that understanding.

Repeated Development Proposals and Community Division

In 2001, I did not imagine that in the 22 years l have lived here, the HOA would try to push through three plans to build on the Parkland.  Persistent attempts to reopen the same issue every few years merely prolong uncertainty and foster ongoing division within the estate.

By contrast, communities such as Leisure Island appear to regard areas like Steenbok Park as permanent community open space rather than future development opportunities. In fact, the maintenance and improvement of the Park is largely funded by individual donations, R600 a year currently, not only from many Leisure Island residents, but from people all over, like my wife and I, who care and want to contribute! Read about it:  Steenbok Park

Today’s Parkland, Yesterday’s Poleyard - How the Contaminated Wood Treatment Area was Mitigated.

Prior to the redevelopment of the island, surface water runoff drained from the wood treatment area (today’s Parkland, yesterday’s Poleyard) eastward into a series of open unlined surface drains. These drains flowed into a shallow retention pond (site of current bird reserve pond) with the overflow water ultimately discharging into the existing reed bed area. The soils beneath these drains and at the bottom of the stormwater pond were heavily contaminated.  Aerial Photo - 1977 - Runoff pond visible

A number of alternatives were considered for treatment of the contaminated area with on-site containment being selected as the most appropriate. The most heavily contaminated areas (Core Contamination Zones) were isolated by capping with clay and cut off walls of bentonite slurry.  The less contaminated areas (Peripheral Contamination Zone) were covered with a 1m layer of clean fill.   A lined pond was built – on the site of the above pond - to receive stormwater run-off from the remediated areas, with the overflow draining into the existing reed bed. The idea of the pond was to limit the flow of sediment into the reed bed. This pond is in the Bird Reserve. See map here:   Map - Parkland contamination zones 

The additional ponds were planned with the landscaping to bring stormwater runoff from the surrounding remediated areas and adjacent houses into the ponds. The ponds were connected so that overflow moved south all the way to the pond in the bird reserve with overflow into the reed bed.  

Effectiveness of the Original Stormwater Design

The overflow from the southernmost pond to the bird reserve pond and into the reed bed appeared to work well in the early years. We moved into our house nearby in May 2004 and my wife’s and my memory is of the reed bed often with visible water. The Grey Herons that used to nest in the reed bed before the redevelopment started continued to nest there many years afterwards. Then they stopped. I suggest that the lack of water, which had protected the nests from rodents, is the reason.  When the reed bed was flooded a few years ago due to wind and a very high tide, the grass area east of the reed beds was full of exhausted rats who had swam out of the flooded reed bed area.   

I do not know when municipal water began being used surreptitiously (at least, to me) to top up the ponds. But it is reasonable to assume that it was started as the stormwater runoff plan was not working as it should. Perhaps even right at the beginning the runoff levels were being altered through lack of control of planting and knowledge.      

However, in 2020, the levels in the runoff drain between this pond and the bird reserve pond were altered when the ponds were modified by the HOA, at great cost, and the runoff stopped. The bird reserve pond was also modified and lined with individual plastic sheets. There does not appear to be any reed bed overflow mechanism, a key factor in the original remediation strategy.

The 2020 pond modifications occurred during a period of considerable tension between trustees and members over a number of contentious estate issues. The redesigned ponds also depended on ongoing municipal water top-ups rather than primarily stormwater runoff, raising questions regarding long-term sustainability.  

In Clause 8 of the Deed of Trust of The Thesen Island Parkland Trust, I note that: (i) the HOA shall maintain “a system of stormwater control… in accordance with the recommendations and under the supervision of the Remediation Consultant”; and (ii) “under the supervision of the Remediation Consultant maintain the integrity of engineered barrier systems on the CCZ”, including taking “reasonable precautions to ensure the drain systems remain functional by not becoming … infilled with silt and vegetation.”

When one considers the modifications made in 2020 to the runoff drain leading to the Bird Reserve Pond, as well as the alterations to the Bird Reserve Pond itself (located within Core Contamination Zone 2), questions arise regarding the nature and appropriateness of those changes. The HOA records should clarify whether these modifications were undertaken following any technical assessment or with the approval and supervision of the Remediation Consultant, as required by Clause 8.

The unknown is how well the stormwater runoff into the top ponds worked before the 2020 remake. However, prior to those modifications, it does not appear that sufficient attention was being given to maintaining original runoff levels, as plants and trees were added over many years without apparent regard to the importance of the drainage design.Like the trees planted at the northmost edge of the Parkland – the tree-less design was to give the homeowners north of the Parkland a view through to the Heads! Not a new urban forest. As a trustee at the time told me, the nursery was full of trees so they were planting everywhere to get rid of them.

Stormwater runoff follows levels. Minor changes in elevation can redirect flow entirely — or stop it altogether.

Conclusion

The planning approval for the redevelopment of the island designated the 11 ha remediated area as permanent open space in the form of a recreational parkland, thereby precluding future development on contaminated land that had been specifically set aside for environmental and amenity purposes.

Thesen Islands has earned a reputation as a uniquely valued residential environment. Preserving that reputation requires careful stewardship, transparency, and sensitivity to issues that repeatedly divide the community.

Ken Rutherford