The River Medway Cable Tunnels are a pair of tunnels carrying high-voltage electricity transmission lines beneath the lower River Medway between the Isle of Grain and Chetney Marshes, Kent. Each tunnel carries a 400 kV electricity circuit on the transmission line between the National Grid substations at Grain and Kemsley; the oil-filled cables are designed to carry 3780 Amps in Winter and 3060 A in Summer. The tunnels are 1,700 metres long, 2.54 m in diameter and between 34 m and 47 m below ordnance datum. The tunnels are connected to a common 6.1 m diameter vertical access shaft at each end. The tunnels were built in anticipation of the commissioning of Grain power station; the crossing would to allow the transmission of power to the 400 kV transmission system to the south. A feasibility report of 1967 addressed both overhead tunnel options for the crossing. Overhead lines would have been longer than the 1,382 metre Swanscombe to Thurrock 400kV crossing and therefore require taller pylons; the tunnels were designed by the Transmission Development and Construction Division of the Central Electricity Generating Board advised by Charles Haswell and Partners.
They were constructed between 1973–6 by John Mowlem & Co. Ltd. and L. G. Mouchel and Partners were consulting engineers for the civil engineering work; the tunnels are constructed from concrete expanding wedge block linings. The tunnels were designed to be constructed through a layer of London Clay. Unexpected beds of gravel and silt were entailed a diversion of the west tunnel; the cables are air cooled to maintain the temperature within design limits at high electricity loads. A forced ventilation system, comprising fans, acoustic enclosures, control systems delivers 58 m3/s of air at 7,500 Pa through each tunnel; the tunnels are provided with Distributed Temperature Sensing fibre system mounted in the crown of each tunnel to detect abnormal temperature conditions. Thames Cable Tunnel Dartford Cable Tunnel 400 kV Thames Crossing
Nikifor Grigoriev, born Nychypir Servetnyk in a small village of Zastavlia, was a paramilitary leader noted for numerous switching of sides during the civil war in Ukraine. He was known as "Otaman Grigoriev", as "Matviy Hryhoriyiv", "Matvey Grigoriev", or "Mykola Grigoriev", he is sometimes misrepresented as the Otaman of the "Green Army". His association with the term "Green Army" is due to collaboration with the army of Otaman Zeleny which fought against the UNR Directory and Denikin's Army. Although he cooperated with Zeleny, this was marginal; the Otaman or "warlord" was born Nychypir Servetnyk in a small village of Zastavlia of Novo-Ushytsia uyezd in Podolia Governorate. Servetnyk served in the cavalry of the Russian Imperial Army in the region of Kherson and participated in Russo-Japanese War in the Russian Far East serving in the Trans-Baikal Host. After his discharge he served as a gendarme in the town of Podolia Governorate. Servetnyk volunteered to the army with the outbreak of the First World War and was enlisted as a Praporshchik to the 56th Zhytomyr Infantry Regiment in 1914.
In course of war he was awarded the Cross of St. George for bravery. Servetnyk rose to the rank of staff captain in the 58th Prague Infantry Regiment and changed his surname to Grigoriev. During this period he became a member of Eser Party. Following the Russian Revolution of 1917, he supported the socialist-oriented Ukrainian Central Rada of the UNR Ukrainian National Republic, he rose to the rank of lieutenant colonel. In April 1918, he took part in the conservative coup d'etat led by Hetman Pavlo Skoropadsky which earned him the rank of colonel. In summer of that year he created his own insurgent army, he joined another revolt in November that year, organized by the Dyrektoria. During the Russian Civil War in December Grigoriev participated in the military campaign against the Russian forces of the South. During that campaign he took Mykolaiv, Ochakiv, Oleshky. Before capturing Mykolaiv he overran the forces of defeated Hetmanate of 545 soldiers, he occupied Mykolaiv on December 13 and appointed himself the city commissioner struggling against the city council.
Grigoriev was appointed a commander of the Ukrainian Kherson Division of the Southern group of General Hrekov until January 29, 1919 the 1st Trans-Dnipro Rifllemen Brigade of the 3rd Trans-Dnipro Riflemen Division. He was forced out of those cities by the Entente forces. During this time the general Hrekov participated in the negotiations with The Entente forces to ally against the Bolsheviks. Grigoriev did not approve that and was upset when Vynnychenko was forced out of the office leading Petliura to head the Directory Committee on February 13. On January 29, 1919 Grigoriev sent a letter to the headquarters of the Zaporizhia Corps in Kremenchuk: On January 25, 1919, Petliura ordered him and Otaman Hulai-Hulenko to join the South-Eastern group against the Armed Forces of South Russia near Alexandrovsk and Pavlohrad. Grigoriev decided to ignore that order, he had not intentions to fight against the White forces as well as the forces of Makhno who operated in the area and were in opposition to the Directorate.
Since that time he systematically ignored all the orders that were coming from the Headquarters of the Ukrainian Army. The similar situation was taken place throughout the Ukrainian Armed Forces at that time. On January 30, Grigoriev sent a representative to the Yelizavetgrad revkom claiming to be the Chairman of the Soviet Emissaries, he sent a telegram to the revkom of Alexandrovsk with an approval for the actions of the Soviet Bolshevik Left-SR government of the Ukrainian SSR. In the beginning of February 1919 Grigoriev attacked the UNR Katerynoslav Kosh of Colonel Kotyk whom he captured as well, he sent a telegram to Red Kharkiv informing that he caught the cat. The Ukrainian Command announced him outlawed, warranting every citizen of the Republic to kill the deserter. On February 2 the Ukrainian left SR Vasyl Ellan-Blakytny arrived at Znamenka to organize the Soviet Ukrainian National government with the help of Grigoriev, but he telegraphed back to Moscow not to hurry with the coalition with Otaman Grigoriev due to possible treachery.
Grigoriev, continued his attacks and stormed Kryvyi Rih and Yelizavetgrad causing UNR forces to withdraw out of Central Ukraine to Podolia. After the withdrawal of UNR forces from Kiev, Otaman Grigoriev continued his negotiations with the Bolsheviks on February 18, 1919. Grigoriev together with his brigade became now part of the Red Army 1st Trans-Dnieper Riflemen Division, while Nestor Makhno led his troops as another brigade of that division and Pavel Dybenko who commanded the division was in charge of another brigade, he was still connected with the Socialist-Revolutionaries who had great influence over the rural population of the country. During that time, he attacked the Askania-Nova preserve and started food requisitioning in the name of Revolution; the head of government of the Soviet Ukraine Christian Rakovsky sent Grigoriev a note of protest in that regard. In short time, April 1919 the preserv