Various Sites Ripon North Yorkshire
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HARROGATE BOROUGH COUNCIL PLANNING COMMITTEE – AGENDA ITEM 6: LIST OF PLANS. DATE: 21 November 2006 PLAN: 11 CASE NUMBER: 06/01791/EIAMAJ GRID REF: EAST 431209 NORTH 470965 APPLICATION NO. 6.500.255.EIAMAJ DATE MADE VALID: 14.08.2006 TARGET DATE: 04.12.2006 WARD: Falls Within 2 Or More VIEW PLANS AT: http://tinyurl.com/yko78k APPLICANT: Environment Agency AGENT: Halcrow Group Ltd PROPOSAL: Construct a flood alleviation scheme in Ripon, which will include a flood storage embankment at Birkby Nab on the River Laver and flood defence walls and embankments in Ripon, Fisher Green and Little Studley. Alma Weir will also be replaced and 100m of riverbed lowered upstream of the weir. LOCATION: Various Sites Ripon North Yorkshire REPORT SITE AND PROPOSAL Ripon has a long history of flooding, the last major events being in 2000 and 2005. As a result these recent events, the Environment Agency undertook various studies to determine how best to manage flooding in the city. Ripon is sited at the meeting of three rivers. The Rivers Skell and Laver flow from the moors to the west and meet at the western boundary of the city. Here they become the River Skell, which flows through Ripon, meeting the River Ure to the east of the city. Following extensive technical, environment and economic analysis the preferred solution involved a combination of options; flood storage on the River Laver upstream of Ripon and the erection of flood defence walls and embankments through the city. The proposed works are designed to protect 500 residential properties against a 1 in 100 year flood event (1% probability). This application seeks planning permission for all the elements of the proposed flood alleviation scheme. For convenience the proposed development can be best considered as 5 discrete areas of work as follows; a) Laver Flood Storage Site (Birkby Nab) b) Borrage Lane c) Alma Weir d) Fisher Green e) North Bridge This report will be structured along these lines. a) Laver Flood Storage Site (Birkby Nab) The site identified for the upstream flood storage area is on the River Laver about 3km north-west of Ripon. The proposed embankment would be about 150m upstream of the farm and Birkby Nab. The River Laver runs to the north of Birkby Nab, which sits on a slight ridge above the floodplain. The river is lined with mature trees on either side. The landscape is dominated by farmland, with a mix of arable and pasture, the fields around Birkby Nab being grazed by horses. Apart from the riverside trees there is a good deal of tree cover in the area, with a woodland Ellington Banks running along the north banks of the River Laver and Kex Beck. There is a young plantation to the west of Birkby Nab and woodland at Cow Myers SSSI on the south bank of Kex Beck. The valley bottom provides a very attractive rural setting of some tranquillity. Apart from Birkby Nab there are only a few other scattered farmsteads in the area, and none of these are visible from many viewpoints on the valley floor. A public footpath runs along the top of the floodplain to the north, and continues through the southern fringe of Ellington Banks. The proposed embankment would stretch across the valley floor just to the north of Birkby Nab. The river turns through 90 degrees at this point, and the embankment would be sited just downstream of this turn to take advantage of the riverside trees which would run parallel to the embankment. The embankment would be 390m long, 8.6m high and 85m across its widest point. There would be a 1 in 4 slope on the upstream side and a 1 in 4.5 slope downstream. The slopes would be overlain with topsoil and grassed, but the spillway would have cellular concrete blocks covered with soil and grassed over. The River Laver would be diverted through two large concrete culverts under the embankment. These would run parallel to one another and would be about 80m long. A 300mm gravel bed would be retained in each culvert to allow the migration of riverbed material through the culvert. The existing flow rate of the River Laver would be maintained through the culverts. Permanent tracks would run along the bottom of both sides of the embankment from the south to allow access to the inlet and outlet. The tracks would not extend along the north side, but a clear width at the bottom of the slope would permit vehicular access if required. A track around the north toe of the embankment would allow access for the farmer. Approximately 20m of new river channel would be created on either side of the culverts. 65m of the abandoned river would be left to create natural backwater habitats. The embankment would be constructed from clay and granular soils which would be extracted from borrow pits in the fields around Birkby Nab. Clay would be taken from an arable field to the west of Birkby Nab. Approximately 110,000 cubic metres would be extracted. This represents excavation to a depth of 4m over an area measuring 300m x 150m. This area would be retuned to arable use. Reserve borrow pit has been identified in neighbouring fields. Granular material would be extracted from a field next to the river, just upstream of the proposed embankment. This would involve extraction to a depth of about 2m over an area measuring approximately 150m x 100m. Reserve borrow pits have been identified on the other side of the river. The restoration of this borrow pit has yet to be confirmed, but there is a possibility that it could be taken out of farming and used for habitat creation. The proposed extraction of these borrow pits represents a mineral operation which would need a separate planning permission from the County Council. The Borough Council would be consulted on any such applications. Temporary haul routes would be constructed from the borrow pits to the embankment site and a site compound would be constructed to the west of Birkby Nab. A new permanent track would be constructed from the existing farm track to the west of Birkby Nab to the embankment. b) Borrage Lane The proposed works in the Borrage Lane area would extend from No 43 Borrage Lane downstream to Borrage Bridge. A total of 260m of flood defences would be constructed along this section. Borrage Lane consists of a variety of mostly detached houses of varying styles. The rear gardens of the houses on the south side of the Lane are mostly terraced and run down to the River Skell. There are fewer houses on the south bank and a footpath provides access along riverside. There is good tree cover on both banks. This area provides an attractive semi-rural character on the edge of the city. The proposed works along this stretch consist of a series of relatively small flood defence walls and embankments in the rear gardens of properties on Borrage Lane. Works would be carried out in the gardens of 15 domestic properties. The works would involve the erection of short sections walling, small grass embankments, the modification and re-alignment of existing features and the waterproofing of properties. Steps and ramps would be provided where necessary to allow access to the bottom the gardens. These would be restricted to the north bank, and none of the proposed structures would exceed 500mm in height. At Borrage Bridge the northern and southern arches would be cleared to provide a better flow. An existing Yorkshire Water outflow would be modified. These works would mean the loss of a large willow tree. c) Alma Weir Alma Weir is close to the centre of Ripon where the river takes on a more urban character, with buildings close to either bank. Nonetheless, there is relatively good tree cover on both banks and riverside paths and amenity areas make for a good quality environment close to the city centre, with views of the Cathedral. The site is within the Conservation Area. The weir itself is a crude concrete structure and not an attractive feature, and being close to the pedestrian bridge is in a particularly prominent location. It is proposed to modify the existing weir and install a series of other weirs upstream to provide a more natural appearance. The foundations of the existing weir would be used as the base for a more nature 'riffle' feature. The outer edges of the weir would be landscaped and a small amenity area would be created. A new gauging weir would be installed upstream, with a further low blockstone weir upstream of that to maintain existing river levels. The riverbed downstream of Alma Weir would be lowered by a depth of up to 1.5m for a distance of 150m. This would increase the capacity of the river channel and provide a more natural channel width and gradient. d) Fisher Green Fisher Green is the area immediately to the east of the by-pass. There is a row of detached house along the south bank, with a group of four houses on the north bank in a rural setting. There is a row of planted cherry trees along the south bank, but ad hoc parking has compromised the landscape quality of this area. A public footpath, part of the 'Ripon Rowel Walk' runs between the houses on the north bank and the riverside. This path leads to a series of stepping stones. This bank is within the Special Landscape Area. On the south bank it is proposed to construct a new piled wall which would project 1m above ground level.