GANSEVALLEI RETIREMENT ESTATE, PLETTENBERG BAY Engineering Services Report

Transcription

1 GANSEVALLEI RETIREMENT ESTATE, PLETTENBERG BAY Engineering Services Report Prepared for: Shelfplett (Pty) Limited PO Box 101 Sunninghill 2157 Prepared by: Royal HaskoningDHV Suite 101, Bloemhof Building 65 York Street George, 6530 Revision: 3 Tel: Fax: dave@jedd.co.za Tel: Fax: george@rhdhv.com Date: January 2016

2 TABLE OF CONTENTS 1. INTRODUCTION EXISTING INFRASTRUCTURE DESIGN CRITERIA FOR THE DETERMINATION OF WATER DEMAND AND SEWAGE FLOWS PRESENT POLICY OF THE PLETTENBERG BAY COUNCIL WATER SEWERAGE ENTRANCE (ACCESS) ROAD STORMWATER MANAGEMENT ELECTRICAL (BULK SERVICES) AUGMENTATION LEVIES... 6 ANNEXURES A. LOCALITY PLAN B. DEVELOPMENT PLAN C. AUGMENTATION LEVIES ESTIMATE D. GLS REPORT : BULK WATER & SEWER SERVICES (JANUARY 2015) Shelfplett (Pty) Limited, Gansevallei Retirement Estate i

3 1. INTRODUCTION 1.1 This report assesses and makes recommendations on the provision of Bulk Water, Sewerage and Electricity services for the Gansevallei Retirement Estate, Plettenberg Bay in the Bitou Municipal Area 1.2 The site is situated east of the N2, towards Port Elizabeth, on Farm 444, Portion 27 and Portion 19, adjacent to Bitou House (Portion 24) in Plettenberg Bay and is currently vacant land. (See Locality Plan Annexure A). 1.3 The attached conceptual site development plan (November 2015 Revised layout, Option 1) indicates that the new development will consist of: 18 luxury apartment sites, 98 apartment units, 188 double story flats, 80 garden units, Clubhouse and frail care, and Road reserves and open space areas. 2. EXISTING INFRASTRUCTURE 2.1 The existing municipal water infrastructure within this area consist of the Goose Valley Reservoir with a capacity of 3 500kl and TWL = 89.7m. Potable water is pumped from the Plettenberg Bay Water Treatment Works (WTW) via a 200mm diameter pipeline to the reservoir. Water from the reservoir gravitates in a 250mm diameter pipeline along and across the N2 national road, to supply water to the Goose Valley Reservoir zone. 2.2 The existing municipal sewer infrastructure adjacent to the development area consists of a 200mm diameter rising sewer main from Goose Valley Pump Station 2 to the GanseVallei Waste Water Treatment Plant (WWTP). Other sewer rising mains from the Keurbooms and Wittedrif Sewerage Schemes also traverse the N2 route past the proposed development en route to the WWTP. 3. DESIGN CRITERIA FOR THE DETERMINATION OF WATER DEMAND AND SEWAGE FLOWS 3.1 The following guidelines and references were used as the basis for the planning of roads, storm water, water, sewerage and solid waste services for the Development: The "Guidelines for Human Settlement Planning and Design" (CSIR Building and Construction Technology, Boutek) in conjunction with the "Guidelines for Engineering Services and Amenities", both hereinafter referred to as "the Guidelines". 4. PRESENT POLICY OF THE PLETTENBERG BAY COUNCIL 4.1 The Council's present policy for the provision of bulk services to any new development is based on the recommendations of the Venter Commission which includes that the developer of a township shall, in addition to providing the internal services for a township, be responsible for the cost of providing a water supply from the Council's Works to the Township, the necessary storage of water and an outfall sewer to the wastewater treatment plant including the cost of all necessary pump Shelfplett (Pty) Limited, Gansevallei Retirement Estate 1

4 stations, pumping mains and reservoirs. In addition, the Developer shall pay to the Council his share of the cost of augmenting the capacity of the Council's bulk water supply and sewerage schemes. The intention is that no additional financial burden should be placed on the present ratepayers. 4.2 At the same time, developers should not be called upon to subsidise the existing ratepayers. Initially it will therefore be necessary to estimate the water demand and sewage flows for each development before calculating the capital levies to be applied. 5. WATER 5.1 The average daily demand (kl/day) for the development is based on the proposed land use mix, and was calculated as follows: Table 1: Water Demands No. 1.1 Zoning / Development Type Number of Erven Demand l/day Total kl/day Residential : Residential Units (luxuary apartments) Residential Units (apartments) Residential Units (attached flats 3 bed) Residential Units (attached flats 2 bed) Residential Units (attached retirement units) Institutional III: Community Facilities (Frail care per bed) Open Space I: Public Open Space (1.5kl/ha) Annual Average Daily Demand AADD (kl/day) According to the attached report from GLS Consulting, the required AADD of the Goose Valley reservoir zone was kl/d (excluding this development). At the time of reporting (GLS January2015), the proposed development increased the figure to 359 kl/d including the development area. The capacity of the existing Goose Valley reservoir is kl/d, which resulted in reservoir storage capacity of 234 hours of the AADD. There is thus sufficient capacity in the existing Goose Valley reservoir to accommodate the proposed development. The November 2015 revised layout has a revised AADD figure of kl/d for the development and therefore this gives a total of = kl/d. The reservoir storage capacity (3500/521*24) is then 161 hrs of the AADD, which is sufficient. 5.3 According to the attached report from GLS Consulting, the existing Goose Valley pump station (situated at Plettenberg Bay Water Treatment Plant) and accompanying 200 mm diameter bulk supply pipeline to the Goose Valley Reservoir have sufficient capacity to accommodate the proposed development. 5.4 Water for the development can be supplied from the Goose Valley Reservoir via a link onto the existing 250mm diameter supply line from the reservoir, as per the recommendations of the GLS report. See GLS report paragraph 1.5, and figure 1, for details of link service item BPW14.4, as well as the recommendation to install master plan item1 (proposed interconnection pipeline) to augment Shelfplett (Pty) Limited, Gansevallei Retirement Estate 2

5 the supply to the Matjesfontein reservoir. It is recommended that credit be given for additional infrastructure installed to be offset against the transportation fees mentioned below. 5.5 Based on the Council s present policy the developer will be responsible for the transportation and augmentation fees as a contribution towards the existing and future water infrastructure. The transportation fees will be determined by the development buying into the existing capacity of the Goose Valley Bulk Water Scheme, as per current Council unit rates for the scheme. The estimated water augmentation levies are also determined by the size of the units and the current published unit rates provided in Annexure C. 6. SEWERAGE 6.1 There is currently no sewer link between the proposed development and Goose Valley Sewer Pump Station 2. The development area will have to connect to the Goose Valley sewer network by way of a new gravity main to a new pumpstation from where it will be pumped via a rising main to the existing Goose Valley network at the Goose Valley Sewer Pump Station The estimated sewage design flow from the development, including infiltration, is as follows: Table 2: Sewage Flows No. Zoning / Development Type Number of Erven Demand l/day Total kl/day 1 Residential: Residential Units (luxuary apartments) Residential Units (apartments) Residential Units (attached flats 3 bed) Residential Units (attached flats 2 bed) Residential Units (attached retirement units) Average Daily Dry Weather Flow (ADDWF) l/s 3 Peak Flow for Peak Factor = l/s 4 Design Peak Flow Infiltration = 15% 6.45 l/s Note that the flows and factors used in the water and sewer masterplanning (GLS Consulting ) are slightly lower than in the table above, presumably because the masterplanning is carried out on a wider area, which lowers the peak factors applied. 6.3 According to the attached report from GLS Consulting, it is proposed in the sewer master plan, that a new sewer pump station (Future Sewer Pstn 10) be constructed at the lowest point on the eastern boundary of Portion 19 of the Farm 444, from where sewerage will then be pumped through a new dedicated 1 465m x 90mm diameter rising main connected to the Goose Valley Sewer PS2. Shelfplett (Pty) Limited, Gansevallei Retirement Estate 3

6 Based on the proposed development s revised layout (Option 1, November 2015), with no development on the east side of the property near to the Bitou river, it is recommended to rather construct the future Pstn 10 (PS10) adjacent to the N2 in the north western corner of the property. A portion of the sewerage on site will gravitate to a small internal sewerage pump station and will then be pumped to the new PS10. Sewerage from the future PS10 will then be pumped directly to the Goose Valley Sewer PS2 over a shorter distance of approximately 810m x 90mm diameter pipeline. 6.4 According to the attached report from GLS Consulting, the Goose Valley Sewer PS2 has a capacity of 21 l/s and will be able to handle the expected 19.4l/s from the pump stations sewer catchment area, including the inflow from the Future Pstn 10 which includes the proposed development. The revised November 2015 layout (Option 1) results in an additional 1.5 l/s peak flow. This increases the required capacity of the Future PS10 by approximately 1.5 l/s, and the total estimated flow would then take up the full capacity of Goose Valley Sewer PS2 at 21 l/s. To further limit peak flows, additional storage can be provided at the detailed design stage of the Future PS10. Note: The duty point of the Goose Valley Sewer PS 2 of 21 l/s should be verified by the Bitou Municipality. (GLS Report). 6.5 According to the attached report from GLS Consulting, the +/2 620m x 200mm diameter sewer rising main between Goose Valley Sewer Pstn 2 and the Ganse Valley Waste Water Treatment Plant (WWTP) has a capacity of 47.1 l/s (@flow velocity 1.5m/s) and has therefore sufficient capacity to accommodate the sewerage flow from the proposed development. 6.6 Based on the Council s present policy the developer will be responsible for the transportation and augmentation fees as a contribution towards the sewer infrastructure. 6.7 The estimated sewer augmentation levies are provided in Annexure C. 7. ENTRANCE (ACCESS) ROAD The proposed development will gain access from the N2 National Road. The existing 4.5 m access to the adjacent agricultural holdings surrounding the development will need to be upgraded to a higher standard. A Traffic Impact Assessment is also necessary as part of the development investigation. The separate assignment was undertaken by SSI Knysna Transport Sector (now Royal HaskoningDHV) and the separate report specifically dealing with the access and traffic related issues are available on request. 8. STORMWATER MANAGEMENT The development is a small sub catchment of the GanseVallei / Bitou / Keurbooms River area. A stormwater network along the internal street network must be planned according to the design flood peaks calculated at detailed design stage. The stormwater management plan, a separate report available on request, outlines the overall stormwater management planning principles for the development. Shelfplett (Pty) Limited, Gansevallei Retirement Estate 4

7 9. ELECTRICAL (BULK SERVICES) With reference to the meeting held with the Bitou Municipal Authority, the supply of electrical bulk services will be based on the following criteria: 9.1 The Bitou Municipality Electrical Department indicated that the existing 11 kv overhead line along the N2 and which crosses the proposed site will be of sufficient capacity to provide bulk supply for these developments. 9.2 A tapoff point from the overhead line will be pointed out to the developer at a later stage. From here the 11 kv ring main underground line will be extended to a suitable position on site to place 2 x free standing MiniSubs. 9.3 High Voltage cabling (11 kv) will run underground to the new site, where it will complete the ring main system within the minisubstation(s) serving dedicated sections of end users. Final power distribution to end users will be via meter kiosks and low Voltage underground cabling. 9.4 The mini substation(s) will be 2 x 500 kva, to be confirmed by the municipality. The minisubstations will be of the 11 kv/400 V 50 Hz 3 phase plus Neutral type. The required high voltage switchgear will be able to break the ring main supply by means of High Voltage T type ring main switch gear. 9.5 Provision has been made for Distribution Kiosks complete with conventional metering device, evenly spread to serve all small holdings and dwellings. 9.6 The average connection to the above has been calculated at 14 kw with a diversity factor (0.285) based on the Rusck formula. 9.7 Once completed, the whole of the infrastructure on the new development will be handed over to the Bitou Municipality as the official Supply Authority for running and maintenance. 9.8 Augmentation fees and Municipal Connection fees are estimated as a direct proportion to the actual kva connection as follows: 384 units ERA of R with diversity of approximately R Above costs exclude VAT and professional fees. It is to be recommended that 2 x 500kVA minsubs (standard size) be installed. Application should be for actual requirement confirmed by the municipality. Shelfplett (Pty) Limited, Gansevallei Retirement Estate 5

8 10. AUGMENTATION LEVIES 10.1 It is mentioned in paragraph 4.1 that the developer is to pay the Council his share of the cost of augmenting the capacity of the Council s bulk water supply and sewerage schemes The augmentation levies are to be paid to the Council by the Developer at the rates effective when the development proceeds The developer should discuss these levies with the Council upon submission of the Services Report. An estimate of the levies payable as of 1st July 2015 is provided in Annexure C. This concludes the report on engineering services for the proposed development of The Jetty, Portion 27 and Portion 19, Ganse Vallei, Plettenberg Bay in the Bitou Municipal Area. Please do not hesitate to contact us should you require any clarification on matters covered in the report. Shelfplett (Pty) Limited, Gansevallei Retirement Estate 6

9 REPORT REFERENCE TITLE : Engineering Services Report for the Gansevallei Retirement Estate, Plettenberg Bay in the Bitou Municipal Area AUTHOR/S : Keith Turner/Paul Lombard/Pierre van Tonder/Piet Strachan CLIENT : Shelfplett (Pty) Limited PROJECT NAME : The Gansevallei Retirement Estate REPORT STATUS : Revision 3 RHDHV PROJECT NUMBER : W01.GRJ CLIENT REFERENCE : S1453 SUBMISSION DATE : 25 January 2016 COPIES OF THIS REPORT HAVE BEEN ISSUED TO REPORT COMPILED BY: : 1. RHDHV George Office 2. Bitou Municipality 3. Shelfplett 47 (Pty) Ltd 4. Wendy Floyd PAUL LOMBARD PROJECT MANAGER 2016/01/25 Date REPORT APPROVED BY: KEITH TURNER PR ENG PRINCIPAL 2016/01/25 Date Shelfplett (Pty) Limited, Gansevallei Retirement Estate 7

10 ANNEXURE A: LOCALITY PLAN Shelfplett (Pty) Limited, Gansevallei Retirement Estate 8

11 Shelfplett (Pty) Limited, Gansevallei Retirement Estate 9

12 ANNEXURE B: DEVELOPMENT PLAN Shelfplett (Pty) Limited, Gansevallei Retirement Estate 10

13 Shelfplett (Pty) Limited, Gansevallei Retirement Estate 11

14 ANNEXURE C: AUGMENTATION LEVIES ESTIMATE Shelfplett (Pty) Limited, Gansevallei Retirement Estate 12

15 BITOU MUNICIPAL AREA: PLETTENBERG BAY: GANSEVALLEI RETIREMENT ESTATE WATER / SEWERAGE AUGMENTATION LEVIES (EXCLUDING VAT) Small Developments (1 3 Units) R R Rev.3 25 January 2016 Total Augmentation Levy for Water R Actual No of Consumers Water Augmentation fees Category Charges From 1 July 2015 Augmentation Levies Single Residential Erven Erven up to 600 m2 R R Erven from 601 up to 800 m2 R R Erven from 801 up to 1000 m2 R R Erven from 1001 up to 1200 m2 R R Erven from 1201 up to 1400 m2 R R Erven from 1401 up to 1600 m2 R R Erven from 1601 up to 1800 m2 R R Erven from 1801 up to 2000 m2 R R Erven over 2000 m2 R R Group housing / Resort Zone 40 Units up to 100 m2 R R Units from 101 up to 120 m2 R R Units from 121 up to 140 m2 R R Units from 141 up to 160 m2 R R Units from 161 up to 180 m2 R R Units from 181 up to 200 m2 R R Units over 200 m2 R R General Residential Flats up to 100 m2 R R 140 Flats from 101 up to 120 m2 R R up to 150 m2 R R Units over 150 m2 R R Other Shops and offices (per 100 m2) R R 30 Hotels (per bed) Frail Care R R Restaurants (per seat) R R Camps & Caravans (per person) R R Small Developments (1 3 Units) R R Total Augmentation Levy for Water R Actual No of Consumers Sewage Augmentation fees Category Charges From 1 July 2015 Augmentation Levies Dwellings Single Residential R R 196 Group housing / Resort Zone R R General residential / Flats R R Shops & Offices (Per 100 m 2 ) R R 30 Hotels (per bed) Frail Care R R Restaurants (per seat) R R Camps & Caravans (per person) R R Small Developments (1 3 Units) R R Total Augmentation Levy for Sewage R Total Augmentation Levy for Water and Sewage R Shelfplett (Pty) Limited, Gansevallei Retirement Estate 13

16 ANNEXURE D: GLS REPORT 21 JANUARY 2015 DEVELOPMENT OF PORTIONS 27 & 19 OF FARM 444 (JETTY DEVELOPMENT), PLETTENBERG BAY : CAPACITY ANALYSIS OF THE BULK WATER & SEWER SERVICES Shelfplett (Pty) Limited, Gansevallei Retirement Estate 14