title: Optimising the effectiveness of sediments retention ponds for Waikato soil materials

authors: Fazli, Bashirah Mohd

subjects: Earthwork

abstract: Current Waikato sediment retention pond design is based on guidelines developed by the Auckland Regional Council. As soils in the Auckland and Waikato Regions are different, there is a need to investigate the effectiveness of sediment retention ponds in retaining sediments from Waikato soil materials. The objectives of this study were to:
i) do a comparison between pipette, hydrometer and lasersizer methods for determining soil particle size and to characterise the sand, silt and clay in a range of Waikato soil materials,
ii) evaluate turbidity and suspended solid concentration between the inlet and outlet of sediment retention ponds, and
iii) investigate the use of chemical treatment (flocculants) in assisting sediment settling.
Ten samples representing a range of Waikato soil materials were collected. Particle size was determined using hydrometer, pipette and lasersizer analysis. The pipette and hydrometer gave similar results. Lasersizer analyses were similar to pipette-hydrometer analyses for six samples. The remaining four samples analysed by lasersizer did not give a close agreement to conventional methods. However, error bars showed that between-sample variability was not large. The pipette was found to be the most reliable method for determination of particle size, however the lasersizer gave fast measurements which were easily repeatable. The soil texture of the ten Waikato soil materials tested ranged from sand to clay.
A rain gauge connected to an autowater sampler was installed at the inlet of two sediment retention ponds, one at SH1 in Piarere and the other at a quarry in Ngaruawahia. Water samples were collected when rainfall reached 2mm in the previous 30 minute period. Samples were analysed for turbidity and suspended solids.
The sediment retention ponds at both sites were effective, reducing suspended solids and turbidity by at least 94%. Water samples collected at Piarere showed a 94% reduction in turbidity (from 558.68 NTU to 35.27NTU) and a 97% declination in suspended solids concentrations (from 2365.63mg/L to 78.41mg/L). Results from water samples collected at Ngaruawahia demonstrated a 97% reduction in turbidity (from 491.33 NTU to 14.46 NTU) and a 95% drop in suspended solids concentration (from 210.43 mg/L to 9.5 mg/L). Flocculants (Polyaluminium Chloride, PAC) were being used at the sediment retention pond at Ngaruawahia.
Further investigation into the effectiveness of flocculants in removing sediments from the water column found that samples 1 and 2 collected from the Ngaruawahia study site and allophanic soil materials do not require treatment with flocculants. The recommended dose of 8 ppm/litre of PAC was sufficient to treat sediment runoff without lowering pH level to a point that might induce aluminium toxicity in aquatic life of downstream rivers and streams for Ngaruawahia 3 and coarse materials of Hinuera Formation. PAC doses of 2.7ppm in the Hamilton Ash materials and 5.3 ppm in Hinuera Formation (fine materials) were sufficient to ensure flocculation. For the Piarere soil materials an 8 ppm PAC dose gave reasonable flocculation and 10.7 ppm PAC further reduced the turbidity after 24 hours.

text: Optimising the effectiveness of sediments retention ponds for Waikato soil materials Current Waikato sediment retention pond design is based on guidelines developed by the Auckland Regional Council. As soils in the Auckland and Waikato Regions are different, there is a need to investigate the effectiveness of sediment retention ponds in retaining sediments from Waikato soil materials. The objectives of this study were to:
i) do a comparison between pipette, hydrometer and lasersizer methods for determining soil particle size and to characterise the sand, silt and clay in a range of Waikato soil materials,
ii) evaluate turbidity and suspended solid concentration between the inlet and outlet of sediment retention ponds, and
iii) investigate the use of chemical treatment (flocculants) in assisting sediment settling.
Ten samples representing a range of Waikato soil materials were collected. Particle size was determined using hydrometer, pipette and lasersizer analysis. The pipette and hydrometer gave similar results. Lasersizer analyses were similar to pipette-hydrometer analyses for six samples. The remaining four samples analysed by lasersizer did not give a close agreement to conventional methods. However, error bars showed that between-sample variability was not large. The pipette was found to be the most reliable method for determination of particle size, however the lasersizer gave fast measurements which were easily repeatable. The soil texture of the ten Waikato soil materials tested ranged from sand to clay.
A rain gauge connected to an autowater sampler was installed at the inlet of two sediment retention ponds, one at SH1 in Piarere and the other at a quarry in Ngaruawahia. Water samples were collected when rainfall reached 2mm in the previous 30 minute period. Samples were analysed for turbidity and suspended solids.
The sediment retention ponds at both sites were effective, reducing suspended solids and turbidity by at least 94%. Water samples collected at Piarere showed a 94% reduction in turbidity (from 558.68 NTU to 35.27NTU) and a 97% declination in suspended solids concentrations (from 2365.63mg/L to 78.41mg/L). Results from water samples collected at Ngaruawahia demonstrated a 97% reduction in turbidity (from 491.33 NTU to 14.46 NTU) and a 95% drop in suspended solids concentration (from 210.43 mg/L to 9.5 mg/L). Flocculants (Polyaluminium Chloride, PAC) were being used at the sediment retention pond at Ngaruawahia.
Further investigation into the effectiveness of flocculants in removing sediments from the water column found that samples 1 and 2 collected from the Ngaruawahia study site and allophanic soil materials do not require treatment with flocculants. The recommended dose of 8 ppm/litre of PAC was sufficient to treat sediment runoff without lowering pH level to a point that might induce aluminium toxicity in aquatic life of downstream rivers and streams for Ngaruawahia 3 and coarse materials of Hinuera Formation. PAC doses of 2.7ppm in the Hamilton Ash materials and 5.3 ppm in Hinuera Formation (fine materials) were sufficient to ensure flocculation. For the Piarere soil materials an 8 ppm PAC dose gave reasonable flocculation and 10.7 ppm PAC further reduced the turbidity after 24 hours.

year: 2010

title: Investigating content representations (CoRes) as pedagogical tools for science teacher education

authors: Hume, Anne Christine

abstract: In this article Anne Hume discusses how use of scholarship and action research led me to introduce an intervention into my science education programmes called Content Representations (CoRes). My initial findings strongly indicate CoRes could be very useful tools for helping student teachers develop the professional knowledge base they need for teaching.

text: Investigating content representations (CoRes) as pedagogical tools for science teacher education In this article Anne Hume discusses how use of scholarship and action research led me to introduce an intervention into my science education programmes called Content Representations (CoRes). My initial findings strongly indicate CoRes could be very useful tools for helping student teachers develop the professional knowledge base they need for teaching.

year: 2010

title: Nga Taumata o te Moana - A return to rangatiratanga over the takutai moana

authors: Downs, Season-Mary

subjects: takutai moana

abstract: The Foreshore and Seabed Act 2004 extinguished Māori customary rights to the foreshore and seabed at law by vesting ownership of the foreshore and seabed in the Crown.   The Act prohibited Māori from having their customary rights recognised at common law by removing the jurisdiction of the courts to investigate customary rights in the takutai moana.  The 2004 Act provided for the recognition of new lesser rights, should Māori be able to meet the tests specified in the legislation.  The legislation was heavily criticised and deemed inconsistent with the treaty,  the rule of law, and international human rights law, where it extinguished the rights of Māori, but not the rights of other right holders.   The legislation was so controversial the 2004 Act was repealed by the Marine and Coastal Area (Takutai Moana) Act 2011.   In the Crown’s mind, the 2011 Act is final, and the longstanding foreshore and seabed dispute related to Māori customary claims to the takutai moana is resolved by the legislation. 

The purpose of the Marine and Coastal Area (Takutai Moana) Act 2011 is to “establish a durable scheme to ensure the protection of the legitimate interests of all New Zealanders” in the takutai moana.    Under the new Act, the takutai moana is now given the special status of “common marine and coastal area”; an area that is “incapable of ownership” by the Crown, Māori or anyone else.   The Act states that it “acknowledges” the “Treaty of Waitangi (Te Tiriti o Waitangi)” and “recognises” the “mana tuku iho” exercised in the common marine and coastal area by iwi, hapū, and whānau as tangata whenua.    Like the 2004 Act, the 2011 Act still bars Māori from obtaining common law customary rights in the takutai moana, and instead puts in place a regime for the recognition of new legal rights that are created by the Act itself.

The primary research question is:  Is the Marine and Coastal Area (Takutai Moana) Act 2011 consistent with te Tiriti o Waitangi, the Māori version of the treaty?

The primary research question is answered by examining the colonial experience of Te Kapotai, a coastal hapū (tribe) in the Southern Bay of Islands from pre-te Tiriti times through to the present day.  It provides an account of how, over time, Crown law, policy and practice have eroded the ability of Te Kapotai to exercise their rangatiratanga (authority) over their takutai moana.  This thesis concludes that the 2011 Act is inconsistent with te Tiriti for four key reasons:
1.	The Act was developed and implemented without negotiation and consent from Māori;
2.	The Act continues to remove the customary rights and procedure for recognition of those rights that were previously available at common law; 
3.	The Act fails to provide for the exercise of rangatiratanga by Māori over the takutai moana as guaranteed under Article 2 of te Tiriti o Waitangi; and 
4.	The Act is in breach of the principle of equity and equal treatment under Article 3 of te Tiriti o Waitangi where it treats Māori and their rights to the takutai moana differently to how all other right/interest holders in the foreshore and seabed are treated.

This research recommends a multifaceted approach to resolving the takutai moana issue, which includes pausing the implementation of the 2011 Act, and the development of interim options to increase Māori participation in the management of the takutai moana.  It promotes that a transformational approach to the takutai moana issue can be achieved when te Tiriti is implemented, and when Māori can exercise rangatiratanga over the takutai moana in a manner that was intended under te Tiriti o Waitangi.

text: Nga Taumata o te Moana - A return to rangatiratanga over the takutai moana The Foreshore and Seabed Act 2004 extinguished Māori customary rights to the foreshore and seabed at law by vesting ownership of the foreshore and seabed in the Crown.   The Act prohibited Māori from having their customary rights recognised at common law by removing the jurisdiction of the courts to investigate customary rights in the takutai moana.  The 2004 Act provided for the recognition of new lesser rights, should Māori be able to meet the tests specified in the legislation.  The legislation was heavily criticised and deemed inconsistent with the treaty,  the rule of law, and international human rights law, where it extinguished the rights of Māori, but not the rights of other right holders.   The legislation was so controversial the 2004 Act was repealed by the Marine and Coastal Area (Takutai Moana) Act 2011.   In the Crown’s mind, the 2011 Act is final, and the longstanding foreshore and seabed dispute related to Māori customary claims to the takutai moana is resolved by the legislation. 

The purpose of the Marine and Coastal Area (Takutai Moana) Act 2011 is to “establish a durable scheme to ensure the protection of the legitimate interests of all New Zealanders” in the takutai moana.    Under the new Act, the takutai moana is now given the special status of “common marine and coastal area”; an area that is “incapable of ownership” by the Crown, Māori or anyone else.   The Act states that it “acknowledges” the “Treaty of Waitangi (Te Tiriti o Waitangi)” and “recognises” the “mana tuku iho” exercised in the common marine and coastal area by iwi, hapū, and whānau as tangata whenua.    Like the 2004 Act, the 2011 Act still bars Māori from obtaining common law customary rights in the takutai moana, and instead puts in place a regime for the recognition of new legal rights that are created by the Act itself.

The primary research question is:  Is the Marine and Coastal Area (Takutai Moana) Act 2011 consistent with te Tiriti o Waitangi, the Māori version of the treaty?

The primary research question is answered by examining the colonial experience of Te Kapotai, a coastal hapū (tribe) in the Southern Bay of Islands from pre-te Tiriti times through to the present day.  It provides an account of how, over time, Crown law, policy and practice have eroded the ability of Te Kapotai to exercise their rangatiratanga (authority) over their takutai moana.  This thesis concludes that the 2011 Act is inconsistent with te Tiriti for four key reasons:
1.	The Act was developed and implemented without negotiation and consent from Māori;
2.	The Act continues to remove the customary rights and procedure for recognition of those rights that were previously available at common law; 
3.	The Act fails to provide for the exercise of rangatiratanga by Māori over the takutai moana as guaranteed under Article 2 of te Tiriti o Waitangi; and 
4.	The Act is in breach of the principle of equity and equal treatment under Article 3 of te Tiriti o Waitangi where it treats Māori and their rights to the takutai moana differently to how all other right/interest holders in the foreshore and seabed are treated.

This research recommends a multifaceted approach to resolving the takutai moana issue, which includes pausing the implementation of the 2011 Act, and the development of interim options to increase Māori participation in the management of the takutai moana.  It promotes that a transformational approach to the takutai moana issue can be achieved when te Tiriti is implemented, and when Māori can exercise rangatiratanga over the takutai moana in a manner that was intended under te Tiriti o Waitangi.

year: 2020