PROPOSED REALIGNMENT OF GAUGING WEIRS DOWNSTREAM OF THE BULSHOEK DAM AND IN THE DORING RIVER, WESTERN CAPE PROVINCE Phase 1 – Heritage Impact Assessment Issue Date - 3 December 2015 Revision No. - 2 Project No. - 131HIA PGS Heritage (Pty) Ltd PO Box 32542 Totiusdal 0134, T +27 12 332 5305 F: +27 86 675 8077 Reg No 2003/008940/07 Declaration of Independence The report has been compiled by PGS Heritage, an appointed Heritage Specialist for Zitholele Consulting. The views stipulated in this report are purely objective and no other interests are displayed during the decision making processes discussed in the Heritage Impact Assessment Process. HERITAGE CONSULTANT - PGS Heritage CONTACT PERSON - W Fourie Tel - +27 (0) 12 332 5305 Email - [email protected] SIGNATURE - ______________________________ ACKNOWLEDGEMENT OF RECEIPT CLIENT - Zitholele Consulting CONTACT PERSON - Kariesha Tilakram T: +27 11 207 2060 E: [email protected] SIGNATURE - ______________________________ HIA – Realignment of Gauging Weirs Downstream of the Bulshoek Dam and in the Doring River ii Date - 11 November 2015 Proposed realignment of gauging weirs downstream of the Bulshoek Dam and in Document Title - the Doring River, Western Cape Province Control Name Signature Designation Author W. Fourie Heritage Specialists/ Principal Investigator Reviewed K. Tilakram Zitholele Consulting HIA – Realignment of Gauging Weirs Downstream of the Bulshoek Dam and in the Doring River iii EXECUTIVE SUMMARY PGS Heritage (PGS) was appointed by Zitholele Consulting to undertake a Heritage Impact Assessment (HIA) that forms part of the Basic Environmental Impact Report (BAR) for the proposed realignment of the gauging weirs downstream of the Bulshoek Dam and in the Doring river, Western Cape Province. The following section provides a summary of the project locality, scope, heritage resources, envisaged impacts and recommendations as required by Heritage Western Cape (HWC) in the 12 March 2014 circular. 1 SITE NAME Bulshoek - and Doring river gauging weirs, Clanwilliam and Klawer, Western Cape Province 2 LOCATION Bulshoek gauging weir Doring river gauging weir Erf and farm number: Erf and farm number: Portion 10, Farm - Kromme Valley 117 and Portion 178, Farm - Annex Mielie Draai 384 Portion 1, Farm - Bulshoek 583 Coordinates: 31°51'45.48"S 18°41'9.70"E Coordinates: 31°59'33.37S 18°47'18.38E Matzikama District, Matzikama Local Cederberg district, Cederberg Local Municipality Municipality HIA – Realignment of Gauging Weirs Downstream of the Bulshoek Dam and in the Doring River iv 3 LOCALITY PLAN 4 DESCRIPTION OF PROPOSED DEVELOPMENT The Department of Water and Sanitation (DWS) has identified two existing gauging weirs, the gauging weir directly downstream of the Bulshoek Dam and the Doring River gauging weir, along the Olifants River system that is currently located at an angle to the direction of river flow. The DWS therefore intends to realign the weir and gauging infrastructure to be located at a right angle (i.e. perpendicular) to the direction of water flow, further upgrading the existing gauging instrumentation and engineering additional scour and erosion prevention infrastructure along the flanks. The weirs and gauging structure will function to provide information on the magnitude of flows in the Olifants River. The existing Doring River Weir is located within the Doring River which is a tributary of the Olifants River. The proposed realigned Doring River Weir will be constructed on the footprint of the existing gauging weir, which will be demolished first. The realigned gauging weir downstream of the Bulshoek Dam will be constructed approximately 20 meters upstream of the existing gauging weir within the Olifants River. Graded rocks placed in a layer (i.e. riprap) will be employed as a means for providing river bank and scour protection. HIA – Realignment of Gauging Weirs Downstream of the Bulshoek Dam and in the Doring River v The graded rocks will be sourced from a rock outcrop upstream of the Doring River gauging weir that will be blasted. 5 HERITAGE RESOURCES IDENTIFIED 5.1.1 Gauging weir downstream of the Bulshoek Dam a) Site BHW 001 GPS: 31º 59’ 32.8” S 18º 47’ 18.6” E The existing gauging weir is situated approximately 20m further downstream of the proposed development of the new weir. This weir is brick and cement built and measures approximately 112m in length and approximately 1.2m high. The weir was constructed on rocky outcrops across the Olifants River and was designed to be grounded and let no water through at the bottom. Its purpose is to gauge water flow from the river. A water gauging, control room forms part of the weir. This control room was constructed on top of the weir wall next to the overflow section of the weir. According to the DWS website measurements in the Olifants River at Bulshoek Dam started on 1 April 1923. During dam rehabilitation work performed by DWS in the early 2000's, the wall of an old diversion weir across the Olifants River was discovered nearly 430m downstream of the dam (BHW001). This structure was partially lowered to incorporate a 9m long Crump weir gauging structure in an attempt to measure the leakages from the dam into the river. No record exist of the original broad-crested diversion structure, but it is assumed that this structure was originally used to divert water into an irrigation canal before the construction of Bulshoek Dam. The structure or part of the structure is older than 60 years and most probably dates between 1921 and 1948 as shown by flow data and gauge information received from DWS. The weir is older than 60 years and protected under section 34 of the NHRA. It cannot be seen as a unique example of this type of gauging structures as numerous similar examples HIA – Realignment of Gauging Weirs Downstream of the Bulshoek Dam and in the Doring River vi exist along the Olifants River as well as further afield. The site is graded as generally protected (GP.B) and will not require further mitigation work. 5.1.2 Structures just outside the study area b) Site BHW 002 GPS: 31º 59’ 45.9” S 18º 47’ 14.5” E The Bulshoek Barrage (Dam Wall), situated approximately 410m further upstream from the proposed development, was completed in 1920 and formed part of one of the oldest irrigation schemes in South Africa. The dam wall measures approximately 143m across and approximately 17m high. The barrage is a massive structure and it features 15 hand operated steel gates to be raised during floods. The construction of the Bulshoek dam started off with planning of an irrigation scheme for the Olifants River in 1908. The original planned design was a solid masonry weir with falling shutters, however by 1912 the Cape Irrigation Department indicated that the proposed design would not be sufficient for the planned irrigation project. The design was amended to add 15 hand-operated Ashford type gates to the top of the proposed weir, in effect creating a full dam wall. The final design was undertaken by the firm Glenfield & Kennedy of Scotland in cooperation with engineer WM Watt. The firm also oversaw the construction of the weir. The construction of the Bulshoek dam was completed in 1924 (The Water Wheel September/October 2010). c) Site BHW 003 GPS: 31º 59’ 32.1” S 18º 47’ 13.7” E A water canal which formed part of the Bulshoek Dam irrigation scheme and which was completed in 1924 is situated on the western banks of the Olifants River approximately 50m west from the proposed weir. This canal system is approximately 83km long and serves irrigation purposes for approximately 9330 hectares of listed land. The canal is lined (with cement/concrete) and varies in size along the system. HIA – Realignment of Gauging Weirs Downstream of the Bulshoek Dam and in the Doring River vii 5.1.3 Doring River gauging weir a) Site DRW 001 GPS: 31º 51’ 46.0” S 18º 41’ 10.3” E The proposed new Doring River Gauging Weir will be situated at the same location as the existing Doring River Gauging Weir. This weir was brick and cement built and measures approximately 130m in length and approximately 2m high. The weir was constructed on rocky outcrops across the Doring River and was designed to gauge water-flow from the river. A water gauging tower forms part of the weir. The tower is situated on the southern banks of the river and just on the upstream side of the weir. According to the DWS website measurements in the Doring River at this point started on 17 May 1908. Only stage (water level in river) readings taken once day are available from this date. A compounded sharp-crested gauging weir structure was commissioned on 9 April 1927 and since then daily stage and a calculated discharge for that stage reading are available. The gauging weir underwent several structural changes since 1927 and in 1948 for instance the structure height was increased. The weir is older than 60 years and protected under section 34 of the NHRA. It cannot be seen as a unique example of this type of gauging structures as numerous similar examples exist along the Olifants River as well as further afield. The site is graded as generally protected (GP.B) and will not require further mitigation work. 5.1.4 Structures just outside the study area b) Site DRW 002 GPS: 31º 59’ 45.9” S 18º 47’ 14.5” E A rock art site was identified approximately 700m to the west of the proposed development. The rock art is on an overhanging rock away from the river. The art contained a few figure and a circle with radiant lines coming from the circle.