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HomeMy WebLinkAboutSP197700077 Action Letter ..s p '''~ ~- '+:J. 473 December 1. 1911 (Regular-Night Meetingl~ n I . I. "The Engineer. in designing a sewage treatment system. for obvious reasons employs the force of gravity to the fullest extent practical. This inevitably leads to the use of a site close to a river or creek. Treatment facilities are set above flood levels but pumps and other appurtenances frequently are located within the floodway. and are designed so that the structure is immune to damage by flooding.... Similar situations can be expected for the location of water pumps at some future time." Staff recommends approval of this amendment: Section 9A-4-4: Pump stations for water or wastewater with their power supply and control devices. holding ponds and other appurtenances to water or wastewater systems." n Mr. Tucker said on November 29. by a vote of 6/0/1. the Planning Commission recommended approval of the staff's wording. 111111111111111111** Agenda Item No.1. SP-11-11. Rivanna Water and Sewer Authority. To allow the Advanced Wastewater Treatment Plant pump station. holding ponds and other appurtenances within the Moores Creek Floodway. The plant is to be located on 49.52 acres zoned A-I Agriculture. located north of Interstate 64 at the confluence of Moores Creek and Rivanna River. County Tax Map 11. Parcel 38B. Rivanna District. (Advertised in the Daily Progress on November 23 and November 30. 1911.) Mr. Tucker gave the staff's report. Request: Advanced wastewater treatment plant pumping stations. holding ponds. and other appurtenances to be located within the Moore's Creek floodway. Acreage: Zoning: Location: 63.43 acres A-I Agricultural North side 1-64. north and south side Moore's Creek between the Rivanna River and Route 20 Interchange. Vehicular access is by way of Franklin Street in the City. through the existing Moore's Creek Treatment Plant. Character of the Area: The site is presently an open knoll and floodplain with evergreen and deciduous trees on the perimeter. r I Comprehensive Plan: The Plan recognizes this site as the location of the future treat- ment plant. The Moore's Creek floodplain is proposed as open space in the plan. Zoning History: SP-313 for AWT plant approved with condition on July 24. 1914. Grading permit for bridge access approved October 24. 1915. G~ading permit to clear and grub property approved August 13.1916. Staff Comment: As described in SP-11-13. the County Engineer has determined that the holding ponds and possibly the pumping stations of the proposed AWT plant are located within the floodway of Moore's Creek. It has also been determined that the location of the holding ponds will cause the predicted intermediate flood elevation to rise 3.68 feet immediately upstream. and the corresponding backwater curve will extend approximately 2.680 feet upstream. This increase in the 100-year flood level will possibly cause flooding of about nine dwellings on Nassau and Franklin Streets which would otherwise possibly not be flboded. n ( The County Engineer has informed the staff that there is no way to relocate the holding ponds on the site and have them function. He states. "The holding ponds are a requirement of the State Health Department. Their purpose is to prevent the discharge of raw se~age into the receiving stream in the event of a power failure or some other untoward ha~pening. This requires that they be placed at an elevation that allows flow by gravity from the treatment plant." The pump stations to be located on the north side of Moore's Creek are not expected to have a measurable effect on flooding. according to the County Engineer. either to raise its level or increase the velocity of flow. He states that the proposed AWT facility incorporates the existing Moore's Creek plant and interceptor into its design. and that there is no practical way to relocate a pumping station outside the floodway. n The influent pump station is located at the end of the Moore's Creek inter- ceptor. the effluent pump station is located at the outfall line from the Moore's Creek Plant. The second station makes possible the use of the exist- ing plant as part of the new facility. The County Engineer has recommended that Rivanna Water and Sewer Authority be required to obtain flood easements over the properties in question. Another alternative would be the widening of the Moore's Creek channel in the vicinit of the holding ponds. Staff does not have any problem with the location of the pumping stations within the floodway. since it is functionally necessary. The extemsive fill required for the holding ponds and the resulting impact on the 100- year flood level is not desirable. However. there does not appear to be any choice but to locate the ponds as shown. Tf" +-ho 'Q"'."'.o............. IlH+-.....""'_-4'4-..... 4="........:1... 4-\......4- .....11..:1..........-- ....'l..._ ,."_____1_ ...,~--.,- -,---- 414 S (' lefT"? - T-=I- December 7, 1977 (Regular-Night Meeting) Staff recommends approval subject to: 1. Rivanna'Water and Sewer Authority shall make every attempt through proper engineering methods to reduce the flooding impact of the proposed holding ponds; 2. If necessary, the Rivanna Water and Sewer Authority shall proceed forthwith to obtain flood easements over those properties that are subject to additional flooding by reason of the construction of the holding ponds." Mr. Tucker said the Planning Commission, on November 29, 1977, by a vote of 6/0/1, re- commended approval with the following condition: "1. The Rivanna Water and Sewer Authority shall widen or deepen the Moore's Creek channel to eliminate the additional 3.68 feet of flood elevation caused by the holding ponds." Mr. J. Harvey Bailey, County Engineer, reported that he had discussed the problem of rising water due to the holding ponds with an hydrologic expert, and said that original calculations may have been in error. He reported that additional analysis may prove that the cause of additional flooding may be caused by the river below the treatment station, rather than from the holding ponds. He recommended that the last condition as recommended by the Planning Commission be changed to allow for the possible revision in flood figures. Mr. Bailey said that the Rivanna Water and Sewer Authority was anxious to have this project bid. Mr. Harry Marshall, Attorney for the Rivanna Water and Sewer Authority, suggested that the Board approve the three reques~with the condition that the Rivanna conduct an engineer- ing study to determine if indeed a channel change is required. If so, they will be obligated to make the necessary change; if no change is found necessary they could proceed with the permission of the County Engineer. Mr. George Williams, of the Rivanna Authority, reported that their consultant, Mr. Krebbs, was scheduled to complete his study of the project some time in early January, 1978, and at that time, bids for the project would be taken. o J Mr. Roudabush suggested the rewording of condition number four to state: "The Rivanna Water and Sewer Authority shall widen, deepen, or rechannel Moore's Creek to eliminate any additional flooding which may be caused by the holding ponds", stating that any exact figures should be left out. Dr. Iachetta stated his concern for the nine families who would be affected by the backing up of Moore's Creek if the situation is not handled correctly. Mr. Marshall said the Rivanna Authority would be more than cautious in protecting property of residents and businesses in the area, because damage suits would be far more costly than the initial study to correct the problem. No one else wished to speak either for or against these three petitions, and Mr. Fisher declared the public hearing closed, but stated that if this matter is deferred, the pu~lic hearing may be reopened at a future date. Mr. Roudabush offered motion to approve SP-77-73 with the first three conditions're- commended by the Planning Commission; changing condition N'four to read: "The tree line (the required 50 foot tree buffer) along Moore's Creek may be eliminated if the engineering study to be performed by the Rivanna Water and Sewer Authority dictates that it is necessary to take steps to widen, deepen or rechannel Moore's Creek". Motion was seconded by Dr. Iachetta and carried by the fOllowing recorded vote: AYES: Mrs. David and Meesrs. Dorrier, Fisher, Hendey, Iachetta and Roudabush. NAYS: None. ........ Motion was then offered by Mrs. David, seconded by Mr. Dorrier, to amend Section 9A-4 of the Zoning Ordinance by adding Section 9A~4-4 under uses by speCial permit. (Wording set out above.) Roll was called, and motion carried by the following recorded vote: AYES:.' Mrs. David and Messrs. Dorrier, Fisher, Henley, Iachetta and Roudabush. NAYS: None. ........ Motion was then offered by Mr. Roudabush, seconded by Mrs. David to approve SP-77-77 but rewording the recommended condition to read as follows: "The Rivanna Water and Sewer Authorit shall take whatever steps are necessary, including, but not limited to, widening, deepening or reChanneling of Moores Creek to eliminate any additional flooding which may be caused by con- I struction of the holding ponds". Roll was called, and motion carried by the following re- corded vote: ! L... AYES: Mrs. David and Messrs. Dorrier, Fisher, Henley, Iachetta and Roudabush. NAYS: None. '- Agenda Item No.8. Runoff Control Ordinance as related to proposed Reservoir Protective District. Mh. Agnor noted memorandum dated December 1, 1977, from Mr. J. Harvey Bailey, County Engineer and Mr. Robert W. Tucker, County Planner, which follows: SUBJECT: Runoff Control Ordinance and Proposed Reservoir Protective District I' L The Engineering and Planning staffs have prepared the fOllowing report in order to give you and the Board of Supervisors an overview of the Runoff Control Ordinance since its adoption in September, 1977, and a comparison of this ordinance with the proposed Reservoir Protective District followed by our recommendations. Runoff Control Ordinance Subsequent to the adoption of the Runoff Control Ordinance,the Runoff Control Official has reviewed a number of applications which involve single lots and one , application of a high density development. In every case,some level of treatment of the runoff has been required,and in the case of the high density development, it ........... .p....u........; ..........................."1-.1.0 +...... on,.,".........."Aa+-a +....0. n1J:lt'l +-n mlClolCl~ t-n,::t. 'TtAnll11"tjCloTnIDTl+'R' nf' 1:hp n,..t1'inAn~p_